B族链球菌(group B Streptococcus, GBS)可导致孕妇早产、宫内感染和新生儿化脓性脑膜炎、败血症和肺炎等多种疾病甚至死亡。美国疾病预防控制中心指南建议所有孕产妇在孕35~37周应进行GBS筛查,对检测阳性的孕产妇进行产时抗生素预防。...B族链球菌(group B Streptococcus, GBS)可导致孕妇早产、宫内感染和新生儿化脓性脑膜炎、败血症和肺炎等多种疾病甚至死亡。美国疾病预防控制中心指南建议所有孕产妇在孕35~37周应进行GBS筛查,对检测阳性的孕产妇进行产时抗生素预防。使用抗生素会对人体产生副作用且无法预防GBS迟发性感染,随着细菌抗生素耐药逐年严重,探索成本更低、更有效的预防GBS定植感染措施尤为重要。GBS是一种可通过食物传播的人畜共患病病原体,研究其在肠道中的定植至关重要。肠道内共生细菌可通过肠道定植抗性机制抑制肠道病原体的定植和扩张,减少肠道GBS逆行性感染生殖道的风险,具有成为防治GBS的一级预防措施的潜力。本文着重探讨肠道定植抗性对GBS定植感染的影响,以及基于此的益生菌应用。展开更多
目的通过调查重症监护病房(intensive care unit,ICU)一起肺炎克雷伯菌(Klebsiella pneumoniae,KP)聚集性定植原因,评价防控措施的有效性。方法对2020年4月8日至6月28日入住ICU检出KP的患者进行流行病学调查及其病房周围环境监测,并进...目的通过调查重症监护病房(intensive care unit,ICU)一起肺炎克雷伯菌(Klebsiella pneumoniae,KP)聚集性定植原因,评价防控措施的有效性。方法对2020年4月8日至6月28日入住ICU检出KP的患者进行流行病学调查及其病房周围环境监测,并进行药敏试验。结果2020年第二季度KP检出例次阳性率为10.58%(20/189),高于去年同期水平(χ2=6.68,P=0.01),调查期内入住ICU患者119人次,其中10名患者痰培养KP阳性,1例为呼吸机相关性肺炎(ventilator associated pneumonia,VAP),9例为院内定植,其主要发现于4、8、9、11、13、16床,其中8、9两床共计检出5例;对ICU病房环境采样45份,石蜡油瓶表面及导丝盒中检出KP;石蜡油瓶表的KP菌株和10位患者检出的KP抗菌谱完全一致或高度相似。结论本次KP聚集事件传播途径主要考虑为床间交叉使用表面被KP污染的石蜡油瓶,采取相应的防控措施后得到有效控制。展开更多
The main purpose of this study was to examine the effects of plant species diversity and functional composition (the identity of the plant functional groups) on ecosystem stability of Stipa, communities in the Inner M...The main purpose of this study was to examine the effects of plant species diversity and functional composition (the identity of the plant functional groups) on ecosystem stability of Stipa, communities in the Inner Mongolia Plateau. The research work was based on a 12-year study (from 1984 to 1995) of species abundance, diversity, and primary productivity of four Stipa communities, i.e. S. baicalensis Roshev., S. grandis P. Smirn., S, krylovii Roshev., and S. klemenzii Roshev. respectively. The Shnnon-Wiener index was used as a measurement of plant diversity, while functional composition was used to differentiate the functional groups that were included in the communities. The plant species of four Stipa communities were classified into functional groups based on the differences in life forms and ecological groups, which influence their performance in resource requirements, seasonality of growth, tolerance to water stress, and life history. Plant species were classified into five functional groups based on their differences in life form, shrubs and half shrubs, perennial bunch grasses, perennial rhizome grasses, forbs, annuals and biennials. Based on their differences in water requirement these species were classified into four functional groups: xerads, intermediate xerads, intermediate mesophytes, and mesophytes. The results showed: 1) Plant species diversity stabilized ecosystem processes. Shannon-Wiener index were 2.401 4, 2.172 0, 1.624 8, 0.354 3 from S. baicalensis community to S. grandis, S. krylovii and S. klemenzii community, respectively. The dynamics of the aboveground net primary productivity (ANPP) for a 12-year's period showed a reverse pattern, the coefficients of variation of the four communities were 21.94%, 20.63%, 29.21% and 39.72% respectively. 2) The Life form functional group component of diversity was a greater determinant of the ecosystem processes than the species component of diversity. The effects of perennial bunch grasses, perennial rhizome grasses and forbs on community stability were highly significant. 3) The ecological group component of diversity was also a great determinant of the ecosystem processes. The effects of xerads, intermediate xerads, and mesophytes on community stability were also very strong.展开更多
Based on secular fixed_site data in the artificial sand_fixing vegetation district at the southeast fringe of the Tengger Desert, the formative characteristics of soil microbiotic crusts and its influences on vegetati...Based on secular fixed_site data in the artificial sand_fixing vegetation district at the southeast fringe of the Tengger Desert, the formative characteristics of soil microbiotic crusts and its influences on vegetation dynamics were analyzed. Once sand barrier and artificial vegetation have stabilized the surface of the sifting sand, could form aeolian deposition crust and then evolve into algae_dominated crust. Such processes result from the interactions of physical effects of atmospheric dust and silt deposition on sand surface, sinking and raindrop impact, and soil microorganism activities. Under the condition of less than 200 mm precipitation, the presence of microbiotic crust changes the soil hydraulic conductivity, alters the temporal and spatial distribution of the limited precipitation in sand layer and leads to the decline of deep_rooted shrubs. The development of microbiotic crust and subsurface soil affects the plant growth and seed rain distribution, as a result, the diversity of plant species gradually tend to become saturated and finally affects the vegetation stability.展开更多
A comparative study was carried out on the EM_cytochemical localization of calcium and Ca 2+ _ATPase activity in the suspension_cultured cells between the chilling_sensitive maize ( Zea mays L. cv. Black Mexica...A comparative study was carried out on the EM_cytochemical localization of calcium and Ca 2+ _ATPase activity in the suspension_cultured cells between the chilling_sensitive maize ( Zea mays L. cv. Black Mexican Sweet) and chilling_insensitive Trititrigia ( Triticum sect. Trititrigia mackey) at 4 ℃ chilling. When maize and Tyititrigia cells were cultured at 26 ℃, electron microscopic observations revealed that the electron_dense calcium antimonate deposits, an indication of the calcium localization, were localized mainly in the vacuoles, and few was found in the cytosol and nuclei. The electron_dense cerium phosphate deposits, an indication of Ca 2+ _ATPase activity, were abundantly distributed on the plasma membrane (PM). When the cells from both species were cultured at 4 ℃ for 1 and 3 h, an elevation of Ca 2+ level in the cytosol and nuclei was observed, whereas the cerium phosphate deposits on the PM showed no quantitative difference from those of the 26 ℃_cultured cells, indicating that the enzymatic activities were not altered during these chilling periods. However, there was a distinct difference in the dynamics of the Ca 2+ distribution and the PM Ca 2+ _ATPase activity between maize and Trititrigia when chilled at 4 ℃ for 12, 24 and 72 h. In maize cells, a large number of Ca 2+ deposits still existed in the cytosol and nuclei, and the PM Ca 2+ _ATPase became less and less active, and even inactive at all. In Trititrigia cells, the increased cytosolic and nuclear Ca 2+ ions decreased after 12 h chilling. By chilling up to 24 and 72 h, the intracellular Ca 2+ concentration had been restored to a similar low level as those of the warm temperature_cultured cells, while the activity of the PM Ca 2+ _ATPase maintained high. The transient cytosolic and nuclear Ca 2+ increase and the activities of PM Ca 2+ _ATPase during chilling are discussed in relation to plant cold hardiness.展开更多
On the basis of data from Soil Test and Formula Fertilization project in Qimen county,we employed Geographic Information System Software ArcGIS 9.2 and CLRMIS（Cultivated Land Resource Management Information System at...On the basis of data from Soil Test and Formula Fertilization project in Qimen county,we employed Geographic Information System Software ArcGIS 9.2 and CLRMIS（Cultivated Land Resource Management Information System at County Scale） to establish region-specific estimation index system for tea cultivation in Qimen County by determining the estimation units,and carried out quantitative estimation analysis on tea cultivation there via comprehensive evaluation indices for natural elements of cultivated land.The results showed that the highly suitable,suitable,reluctantly suitable and unsuitable acreages are 5 665.8,8 327.1,8 415.9 and 11 979.9 hm2 respectively,accounting for 24.0%,35.3%,35.7% and 5.1% of the total acreage of cultivated land.These results would facilitate the production of high yield and quality tea in Qimen County.展开更多
The random amplified polymorphic DNA (RAPD) technique was used to amplify DNA fragment, aiming at finding markers linked to the sex determination in Ginkgo biloba L. One thousand and two hundred random decamers had be...The random amplified polymorphic DNA (RAPD) technique was used to amplify DNA fragment, aiming at finding markers linked to the sex determination in Ginkgo biloba L. One thousand and two hundred random decamers had been screened. Of the 8 372 RAPD bands, only a 682 bp RAPD marker generated by a primer (S1478) of random decamer sequence, named S1478-682, was found to be associated with the male plants. This marker was present in all male plants and absent in all female plants. Ginkgo trees collected in both Beijing and Shenyang, China were tested using primer S1478. Positive results were obtained, suggesting S1478-682 could be utilized as a reliable RAPD marker to detect the sexuality of Ginkgo.展开更多
A novel active steering system with force and displacement coupled control(the novel AFS system) was introduced,which has functions of both the active steering and electric power steering.Based on the model of the nov...A novel active steering system with force and displacement coupled control(the novel AFS system) was introduced,which has functions of both the active steering and electric power steering.Based on the model of the novel AFS system and the vehicle three-degree of freedom system,the concept and quantitative formulas of the novel AFS system steering performance were proposed.The steering road feel and steering portability were set as the optimizing targets with the steering stability and steering portability as the constraint conditions.According to the features of constrained optimization of multi-variable function,a multi-variable genetic algorithm for the system parameter optimization was designed.The simulation results show that based on parametric optimization of the multi-objective genetic algorithm,the novel AFS system can improve the steering road feel,steering portability and steering stability,thus the optimization method can provide a theoretical basis for the design and optimization of the novel AFS system.展开更多
Let P（s, δ） be a sphere plant family described by the transfer function set where the coefficients of the denominator and numerator polynomials are affine in a real uncertain parameter vector δ satisfying the Eucl...Let P（s, δ） be a sphere plant family described by the transfer function set where the coefficients of the denominator and numerator polynomials are affine in a real uncertain parameter vector δ satisfying the Euclidean norm constraint ｜｜δ｜｜〈δ. The concept of stabilizability radius of P（s, δ） is introduced which is the norm bound δs for δ such that every member plant of P（s, δ） is stabilizable if and only if ｜｜δ｜｜〈δs. The stabilizability radius can be simply interpreted as the ＇largest sphere＇ around the nominal plant P（s,θ） such that P（s, δ） is stabilizable. The numerical method and the analytical method are presented to solve the stabilizability radius calculation problem of the sphere plants.展开更多
To investigate the influence of root system architectural properties of three indigenous （cold- adapted） shrubs on the hillslope stability of loess deposits in the Xining Basin, northeast part of Qinghai-Tibet Plate...To investigate the influence of root system architectural properties of three indigenous （cold- adapted） shrubs on the hillslope stability of loess deposits in the Xining Basin, northeast part of Qinghai-Tibet Plateau （QTP）, indoor direct shear tests have been conducted on the remolded rooted soil of three shrubs. Test results show that root system architectural indices （root area ratio （RAR）, root length density （RLD） and root density （RD）） of the shrubs decline with depth and the relationship between RAR, RD and depth is exponential, while a power relationship describes the relationship between RLD and depth. The cohesion force of remolded rooted soil for the shrubs initially increases with depth, but it then demonstrates a slightly decreasing trend, which can be described with a power relationship. Power relationships also describe relationships between cohesion force and RAR, RLD and RD for the shrubs. As the growth period increases from lO to 17 months, the incremental increase in RAR is 48.32% ~ 21o.25% for Caragana korshinskii Kom and 0.56% ~ 166.85% for ZygophyUum xanthoxylon （Bunge） Maxim. This proportional increase is notably larger than that for RLD and RD. The increment in RAR is marginally greater for C. korshinskff than it is for Z. xanthoxylon. Correspondingly, the cohesion force incremental rates of remolded rooted soil for C. korshinskii and Z. xanthoxylon are 12.41% ~ 25.22% and 3.45% ~ 17.33% respectively. Meanwhile, as root content increases, the contribution by roots to cohesion force increases markedly until a threshold condition is reached.展开更多
Powdery mildew, which called Sphaerotheca phaseoli in Latin, is one of the major diseases of mungbean （Vigna radiata L.） worldwide, causing up to 50% yield losses. Most mungbean varieties grown in Thailand are susce...Powdery mildew, which called Sphaerotheca phaseoli in Latin, is one of the major diseases of mungbean （Vigna radiata L.） worldwide, causing up to 50% yield losses. Most mungbean varieties grown in Thailand are susceptible to the disease, therefore, new resistant varieties are highly desirable. Three resistant mungbean lines, V4718, V4758 and V4785, were identified from the AVRDC collection. In this study, the authors compared the resistance levels among these 3 lines and tested the allelic relationship among these resistance genes. Three crosses, V4718 × V4758, V4718 × V4785 and V4758 × V4785, were made and the F1 hybrids were selfed to generate the F2 populations and crossed to a susceptible variety, CN72 to generate the F1 × S populations. In the F1 × S and F2 populations, the resistance segregated in a ratio of 3 Resistant （R）：I Susceptible （S） and 15R：IS, respectively for all three crosses. These results indicate that a single dominant gene confers resistance to powdery mildew in each resistant line and these resistance genes are non-allelic. The authors are currently transferring these resistance genes into commercial varieties to provide durable resistance to powdery mildew.展开更多
Unsystematic selection and planting of tree seedlings in road borders, forest regeneration, development of parks and green spaces which are incompatible with the given climate zone, is a kind of interference and viola...Unsystematic selection and planting of tree seedlings in road borders, forest regeneration, development of parks and green spaces which are incompatible with the given climate zone, is a kind of interference and violation of ecosystem privacy. Therefore, the stability and persistence of species in the forest protection is important for planners of natural resources. Field station of spreading Dehloran aquifer is one of the major forestations in Ilam province. It aimed of protecting the soil and underground water table feeding in hot dry plains of Mosian, which have been planted with native and non-native species. In the present article 100 trees of each species were planted during the years 1998 and 1999 in the station, such as Ziziphus spina-christi, Prosopis juliflora, Eucalyptus camaldulensis and Acacia sp. They were randomly selected and information about this species measured and recorded annually has been used. Finally the data has been analysis; by comparison test to compare the growth and persistence. Results indicate that despite high average in height growth （85.4 cm/year） and relatively large diameter growth （2.43 cm/year）, non-native species of Eucalyptus are not in good condition in terms of viability （36.2 percent） and freshness. On the contrary, the native species of Ziziphus with relatively low in average height and diameter growth （22.64 and 2.28 cm/year respectively） represent a better index of viability （65.4 percent） and freshness.展开更多
A complete hydatidiform mole coexisting with a fetus following in vitro fertilization and embryo transfer (IVF-ET) is a rare event. The diagnosis is often not easy because of the morphological similarity to a partial ...A complete hydatidiform mole coexisting with a fetus following in vitro fertilization and embryo transfer (IVF-ET) is a rare event. The diagnosis is often not easy because of the morphological similarity to a partial mole, but important to the treatment. We present a recent case in which STR polymorphism analysis clearly revealed a different genetic origin for the fetal and molar parts. STR polymorphisms on 15 variable number tandem repeat loci and a gender-determination locus, which were detected by polymerase chain reaction, indicating that the cord/placenta and molar tissue were parental and androgenous, respectively. During follow-up, the patient developed persistent gestational trophoblastic tumor (GTT) which was successfully treated with chemotherapy. In this case, STR polymorphism analysis exactly diagnosed a twin pregnancy consisting of a complete hydatidiform mole and a fetus.展开更多
We investigated the effect of the replacement of dietary fish oil with vegetable oils on the growth and flesh quality of large yellow croaker(Larmichthys crocea). The basal diet(FO) was formulated to contain 66.5% fis...We investigated the effect of the replacement of dietary fish oil with vegetable oils on the growth and flesh quality of large yellow croaker(Larmichthys crocea). The basal diet(FO) was formulated to contain 66.5% fish meal and 6.4% menhaden fish oil; whereas the other 3 experimental diets were formulated by replacing the fish oil with 50% soybean oil(SO50), 100% soybean oil(SO100) and 100% palm oil(PO100), respectively. The 4 diets were randomly assigned to 4 floating sea cages(3.0 m × 3.0 m × 3.0 m), and each was stocked with 250 fish individuals with an initial average weight of 245.29 g ± 7.45 g. The fish were fed to apparent satiation twice a day at 5:00 and 17:00, respectively, for 12 weeks. Experimental analysis showed that the specific growth rate of fish fed SO50 or PO100 were significantly higher than that of fish fed FO or SO100(P<0.05), and crude lipid contents of ventral muscle and viscera were significantly lower in fish fed FO than in those fed the other 3 diets(P<0.05). No significant differences in condition factor, viscerosomatic index, hepatosomatic index, gutted yield and colorimetric values of fish among the dietary treatments were observed(P>0.05). Compared to FO diet, SO50, SO100 and PO100 diets led to substantial decreases in the liquid loss and water loss from fresh fillets(1 d, 4℃)(P<0.05). Similarly, thiobarbituric acid reactive substance(TBARS) values of fillets under different storage conditions(1 d, 4℃; 7 d, 4℃; 4 weeks,-20℃; 8 weeks,-20℃) decreased significantly after partial or complete replacement of fish oil with vegetable oils. These findings indicated that the growth performance and selected flesh quality properties(liquid holding capacity and TBARS value) of large yellow croaker were substantially improved by replacing dietary fish oil with vegetable oils.展开更多
文摘B族链球菌(group B Streptococcus, GBS)可导致孕妇早产、宫内感染和新生儿化脓性脑膜炎、败血症和肺炎等多种疾病甚至死亡。美国疾病预防控制中心指南建议所有孕产妇在孕35~37周应进行GBS筛查,对检测阳性的孕产妇进行产时抗生素预防。使用抗生素会对人体产生副作用且无法预防GBS迟发性感染,随着细菌抗生素耐药逐年严重,探索成本更低、更有效的预防GBS定植感染措施尤为重要。GBS是一种可通过食物传播的人畜共患病病原体,研究其在肠道中的定植至关重要。肠道内共生细菌可通过肠道定植抗性机制抑制肠道病原体的定植和扩张,减少肠道GBS逆行性感染生殖道的风险,具有成为防治GBS的一级预防措施的潜力。本文着重探讨肠道定植抗性对GBS定植感染的影响,以及基于此的益生菌应用。
文摘The main purpose of this study was to examine the effects of plant species diversity and functional composition (the identity of the plant functional groups) on ecosystem stability of Stipa, communities in the Inner Mongolia Plateau. The research work was based on a 12-year study (from 1984 to 1995) of species abundance, diversity, and primary productivity of four Stipa communities, i.e. S. baicalensis Roshev., S. grandis P. Smirn., S, krylovii Roshev., and S. klemenzii Roshev. respectively. The Shnnon-Wiener index was used as a measurement of plant diversity, while functional composition was used to differentiate the functional groups that were included in the communities. The plant species of four Stipa communities were classified into functional groups based on the differences in life forms and ecological groups, which influence their performance in resource requirements, seasonality of growth, tolerance to water stress, and life history. Plant species were classified into five functional groups based on their differences in life form, shrubs and half shrubs, perennial bunch grasses, perennial rhizome grasses, forbs, annuals and biennials. Based on their differences in water requirement these species were classified into four functional groups: xerads, intermediate xerads, intermediate mesophytes, and mesophytes. The results showed: 1) Plant species diversity stabilized ecosystem processes. Shannon-Wiener index were 2.401 4, 2.172 0, 1.624 8, 0.354 3 from S. baicalensis community to S. grandis, S. krylovii and S. klemenzii community, respectively. The dynamics of the aboveground net primary productivity (ANPP) for a 12-year's period showed a reverse pattern, the coefficients of variation of the four communities were 21.94%, 20.63%, 29.21% and 39.72% respectively. 2) The Life form functional group component of diversity was a greater determinant of the ecosystem processes than the species component of diversity. The effects of perennial bunch grasses, perennial rhizome grasses and forbs on community stability were highly significant. 3) The ecological group component of diversity was also a great determinant of the ecosystem processes. The effects of xerads, intermediate xerads, and mesophytes on community stability were also very strong.
文摘Based on secular fixed_site data in the artificial sand_fixing vegetation district at the southeast fringe of the Tengger Desert, the formative characteristics of soil microbiotic crusts and its influences on vegetation dynamics were analyzed. Once sand barrier and artificial vegetation have stabilized the surface of the sifting sand, could form aeolian deposition crust and then evolve into algae_dominated crust. Such processes result from the interactions of physical effects of atmospheric dust and silt deposition on sand surface, sinking and raindrop impact, and soil microorganism activities. Under the condition of less than 200 mm precipitation, the presence of microbiotic crust changes the soil hydraulic conductivity, alters the temporal and spatial distribution of the limited precipitation in sand layer and leads to the decline of deep_rooted shrubs. The development of microbiotic crust and subsurface soil affects the plant growth and seed rain distribution, as a result, the diversity of plant species gradually tend to become saturated and finally affects the vegetation stability.
文摘A comparative study was carried out on the EM_cytochemical localization of calcium and Ca 2+ _ATPase activity in the suspension_cultured cells between the chilling_sensitive maize ( Zea mays L. cv. Black Mexican Sweet) and chilling_insensitive Trititrigia ( Triticum sect. Trititrigia mackey) at 4 ℃ chilling. When maize and Tyititrigia cells were cultured at 26 ℃, electron microscopic observations revealed that the electron_dense calcium antimonate deposits, an indication of the calcium localization, were localized mainly in the vacuoles, and few was found in the cytosol and nuclei. The electron_dense cerium phosphate deposits, an indication of Ca 2+ _ATPase activity, were abundantly distributed on the plasma membrane (PM). When the cells from both species were cultured at 4 ℃ for 1 and 3 h, an elevation of Ca 2+ level in the cytosol and nuclei was observed, whereas the cerium phosphate deposits on the PM showed no quantitative difference from those of the 26 ℃_cultured cells, indicating that the enzymatic activities were not altered during these chilling periods. However, there was a distinct difference in the dynamics of the Ca 2+ distribution and the PM Ca 2+ _ATPase activity between maize and Trititrigia when chilled at 4 ℃ for 12, 24 and 72 h. In maize cells, a large number of Ca 2+ deposits still existed in the cytosol and nuclei, and the PM Ca 2+ _ATPase became less and less active, and even inactive at all. In Trititrigia cells, the increased cytosolic and nuclear Ca 2+ ions decreased after 12 h chilling. By chilling up to 24 and 72 h, the intracellular Ca 2+ concentration had been restored to a similar low level as those of the warm temperature_cultured cells, while the activity of the PM Ca 2+ _ATPase maintained high. The transient cytosolic and nuclear Ca 2+ increase and the activities of PM Ca 2+ _ATPase during chilling are discussed in relation to plant cold hardiness.
文摘On the basis of data from Soil Test and Formula Fertilization project in Qimen county,we employed Geographic Information System Software ArcGIS 9.2 and CLRMIS（Cultivated Land Resource Management Information System at County Scale） to establish region-specific estimation index system for tea cultivation in Qimen County by determining the estimation units,and carried out quantitative estimation analysis on tea cultivation there via comprehensive evaluation indices for natural elements of cultivated land.The results showed that the highly suitable,suitable,reluctantly suitable and unsuitable acreages are 5 665.8,8 327.1,8 415.9 and 11 979.9 hm2 respectively,accounting for 24.0%,35.3%,35.7% and 5.1% of the total acreage of cultivated land.These results would facilitate the production of high yield and quality tea in Qimen County.
文摘The random amplified polymorphic DNA (RAPD) technique was used to amplify DNA fragment, aiming at finding markers linked to the sex determination in Ginkgo biloba L. One thousand and two hundred random decamers had been screened. Of the 8 372 RAPD bands, only a 682 bp RAPD marker generated by a primer (S1478) of random decamer sequence, named S1478-682, was found to be associated with the male plants. This marker was present in all male plants and absent in all female plants. Ginkgo trees collected in both Beijing and Shenyang, China were tested using primer S1478. Positive results were obtained, suggesting S1478-682 could be utilized as a reliable RAPD marker to detect the sexuality of Ginkgo.
基金Project(51005115) supported by the National Natural Science Foundation of ChinaProject(KF11201) supported by the Science Fund of State Key Laboratory of Automotive Safety and Energy,ChinaProject(201105) supported by the Visiting Scholar Foundation of the State Key Laboratory of Mechanical Transmission in Chongqing University,China
文摘A novel active steering system with force and displacement coupled control(the novel AFS system) was introduced,which has functions of both the active steering and electric power steering.Based on the model of the novel AFS system and the vehicle three-degree of freedom system,the concept and quantitative formulas of the novel AFS system steering performance were proposed.The steering road feel and steering portability were set as the optimizing targets with the steering stability and steering portability as the constraint conditions.According to the features of constrained optimization of multi-variable function,a multi-variable genetic algorithm for the system parameter optimization was designed.The simulation results show that based on parametric optimization of the multi-objective genetic algorithm,the novel AFS system can improve the steering road feel,steering portability and steering stability,thus the optimization method can provide a theoretical basis for the design and optimization of the novel AFS system.
基金Project(JSPS.KAKENHI22560451) supported by the Japan Society for the Promotion of ScienceProject(69904003) supported by the National Natural Science Foundation of ChinaProject(YJ0267016) supported by the Advanced Ordnance Research Supporting Fund of China
文摘Let P（s, δ） be a sphere plant family described by the transfer function set where the coefficients of the denominator and numerator polynomials are affine in a real uncertain parameter vector δ satisfying the Euclidean norm constraint ｜｜δ｜｜〈δ. The concept of stabilizability radius of P（s, δ） is introduced which is the norm bound δs for δ such that every member plant of P（s, δ） is stabilizable if and only if ｜｜δ｜｜〈δs. The stabilizability radius can be simply interpreted as the ＇largest sphere＇ around the nominal plant P（s,θ） such that P（s, δ） is stabilizable. The numerical method and the analytical method are presented to solve the stabilizability radius calculation problem of the sphere plants.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.41162010,41572306)provincial key project in science and technologies of Qinghai(Grant No.2003-N-134)+1 种基金Excellent Talents in University of New Century by Ministry of Education of the People’s Republic of China(Grant No.NCET–04–G983)International Science&Technology Cooperation Program of China(Grant No.2011DFG93160)
文摘To investigate the influence of root system architectural properties of three indigenous （cold- adapted） shrubs on the hillslope stability of loess deposits in the Xining Basin, northeast part of Qinghai-Tibet Plateau （QTP）, indoor direct shear tests have been conducted on the remolded rooted soil of three shrubs. Test results show that root system architectural indices （root area ratio （RAR）, root length density （RLD） and root density （RD）） of the shrubs decline with depth and the relationship between RAR, RD and depth is exponential, while a power relationship describes the relationship between RLD and depth. The cohesion force of remolded rooted soil for the shrubs initially increases with depth, but it then demonstrates a slightly decreasing trend, which can be described with a power relationship. Power relationships also describe relationships between cohesion force and RAR, RLD and RD for the shrubs. As the growth period increases from lO to 17 months, the incremental increase in RAR is 48.32% ~ 21o.25% for Caragana korshinskii Kom and 0.56% ~ 166.85% for ZygophyUum xanthoxylon （Bunge） Maxim. This proportional increase is notably larger than that for RLD and RD. The increment in RAR is marginally greater for C. korshinskff than it is for Z. xanthoxylon. Correspondingly, the cohesion force incremental rates of remolded rooted soil for C. korshinskii and Z. xanthoxylon are 12.41% ~ 25.22% and 3.45% ~ 17.33% respectively. Meanwhile, as root content increases, the contribution by roots to cohesion force increases markedly until a threshold condition is reached.
文摘Powdery mildew, which called Sphaerotheca phaseoli in Latin, is one of the major diseases of mungbean （Vigna radiata L.） worldwide, causing up to 50% yield losses. Most mungbean varieties grown in Thailand are susceptible to the disease, therefore, new resistant varieties are highly desirable. Three resistant mungbean lines, V4718, V4758 and V4785, were identified from the AVRDC collection. In this study, the authors compared the resistance levels among these 3 lines and tested the allelic relationship among these resistance genes. Three crosses, V4718 × V4758, V4718 × V4785 and V4758 × V4785, were made and the F1 hybrids were selfed to generate the F2 populations and crossed to a susceptible variety, CN72 to generate the F1 × S populations. In the F1 × S and F2 populations, the resistance segregated in a ratio of 3 Resistant （R）：I Susceptible （S） and 15R：IS, respectively for all three crosses. These results indicate that a single dominant gene confers resistance to powdery mildew in each resistant line and these resistance genes are non-allelic. The authors are currently transferring these resistance genes into commercial varieties to provide durable resistance to powdery mildew.
文摘Unsystematic selection and planting of tree seedlings in road borders, forest regeneration, development of parks and green spaces which are incompatible with the given climate zone, is a kind of interference and violation of ecosystem privacy. Therefore, the stability and persistence of species in the forest protection is important for planners of natural resources. Field station of spreading Dehloran aquifer is one of the major forestations in Ilam province. It aimed of protecting the soil and underground water table feeding in hot dry plains of Mosian, which have been planted with native and non-native species. In the present article 100 trees of each species were planted during the years 1998 and 1999 in the station, such as Ziziphus spina-christi, Prosopis juliflora, Eucalyptus camaldulensis and Acacia sp. They were randomly selected and information about this species measured and recorded annually has been used. Finally the data has been analysis; by comparison test to compare the growth and persistence. Results indicate that despite high average in height growth （85.4 cm/year） and relatively large diameter growth （2.43 cm/year）, non-native species of Eucalyptus are not in good condition in terms of viability （36.2 percent） and freshness. On the contrary, the native species of Ziziphus with relatively low in average height and diameter growth （22.64 and 2.28 cm/year respectively） represent a better index of viability （65.4 percent） and freshness.
基金Supported by Production and Rresearch Projects of Guangdong Province (2007B090400140)
文摘A complete hydatidiform mole coexisting with a fetus following in vitro fertilization and embryo transfer (IVF-ET) is a rare event. The diagnosis is often not easy because of the morphological similarity to a partial mole, but important to the treatment. We present a recent case in which STR polymorphism analysis clearly revealed a different genetic origin for the fetal and molar parts. STR polymorphisms on 15 variable number tandem repeat loci and a gender-determination locus, which were detected by polymerase chain reaction, indicating that the cord/placenta and molar tissue were parental and androgenous, respectively. During follow-up, the patient developed persistent gestational trophoblastic tumor (GTT) which was successfully treated with chemotherapy. In this case, STR polymorphism analysis exactly diagnosed a twin pregnancy consisting of a complete hydatidiform mole and a fetus.
基金supported by the National Key Technologies R&D Program for the 10th and 11th Five-year Plan of China (Grant No.: 2001BA505B-06)
文摘We investigated the effect of the replacement of dietary fish oil with vegetable oils on the growth and flesh quality of large yellow croaker(Larmichthys crocea). The basal diet(FO) was formulated to contain 66.5% fish meal and 6.4% menhaden fish oil; whereas the other 3 experimental diets were formulated by replacing the fish oil with 50% soybean oil(SO50), 100% soybean oil(SO100) and 100% palm oil(PO100), respectively. The 4 diets were randomly assigned to 4 floating sea cages(3.0 m × 3.0 m × 3.0 m), and each was stocked with 250 fish individuals with an initial average weight of 245.29 g ± 7.45 g. The fish were fed to apparent satiation twice a day at 5:00 and 17:00, respectively, for 12 weeks. Experimental analysis showed that the specific growth rate of fish fed SO50 or PO100 were significantly higher than that of fish fed FO or SO100(P<0.05), and crude lipid contents of ventral muscle and viscera were significantly lower in fish fed FO than in those fed the other 3 diets(P<0.05). No significant differences in condition factor, viscerosomatic index, hepatosomatic index, gutted yield and colorimetric values of fish among the dietary treatments were observed(P>0.05). Compared to FO diet, SO50, SO100 and PO100 diets led to substantial decreases in the liquid loss and water loss from fresh fillets(1 d, 4℃)(P<0.05). Similarly, thiobarbituric acid reactive substance(TBARS) values of fillets under different storage conditions(1 d, 4℃; 7 d, 4℃; 4 weeks,-20℃; 8 weeks,-20℃) decreased significantly after partial or complete replacement of fish oil with vegetable oils. These findings indicated that the growth performance and selected flesh quality properties(liquid holding capacity and TBARS value) of large yellow croaker were substantially improved by replacing dietary fish oil with vegetable oils.
