摘要
Among the extended cyclic terpenoid biomarkers reported in literature thus far,the C-3 and/or C-2 methyl-substituted counterparts have been found either in bicyclic drimane series,or in pentacyclic hopane series. Even though the extended tri- and tetracyclic terpane series have been known over two decades,and
基金
Project funded by the State Key Laboratory of Organic Geochemistry, Academia Sinica.
