Lignans from Kadsura angustifolia

Phytochemical investigation of Kadsura angustifolia led to the isolation and identification of 26 lignans and two triterpenoids, including I I new lignans named kadangustins A-K (1-11). The structures and stereochemistry of 1-11 were elucidated by. analys

我国蛇类爬行动物地理分区的聚类分析

本文以属为分类阶元，对我国蛇类爬行动物地理区划的t个区、十八个亚区进行了聚类分析。结果表 明：东洋界和古北界的划分可以明显地从爬行动物的分布中反映出来，但古北界区和亚区的划分则不能反映爬 行动物的地理分布特点。东洋界中，西南区喜马拉雅亚区单独聚为一支，是与其爬行动物主要来自于印度半岛 相～致的；而华南区的台湾亚区则与华中区和西南区的西南山地亚区聚在丁一起，说明将台湾亚区放在华南区 值得商榷。

Deconvolution of overlapped peaks based on the exponentially modified Gaussian model in comprehensive two-dimensional gas chromatography

Comprehensive two-dimensional gas chromatography (GC x GC) has attracted much attention for the analys is of complex samples. Even with a large peak capacity in GC x GC, peak overlapping is often met. In this paper, a new method was developed to resolve overlapped peaks based on the mass conservation and the exponentially modified Gaussian (EMG) model. Linear relationships between the calculated sigma, tau of primary peaks with the corresponding retention time (t(R)) were obtained, and the correlation coefficients were over 0.99. Based on such relationships, the elution profile of each compound in overlapped peaks could be simulated, even for the peak never separated on the second-dimension. The proposed method has proven to offer more accurate peak area than the general data processing method. (c) 2005 Elsevier B.V. All rights reserved.