少妇无码精品23p_亚洲一区无码电影在线观看网站 _悠悠色一区二区_中文字幕亚洲无码第36页

A research group has made a breakthrough in identifying biological compounds from ancient plants which reveal what makes a fossil.

Headed by Zhou Jun from the Kunming Institute of Botany, and Li Chengsen from the Beijing-based Institute of Botany, both working for the Chinese Academy of Science (CAS), the researchers used phytochemical methods to isolate 71 compounds from fossil specimens of Huashan pine and Yunnan hemlock from Pliocene strata and their corresponding contemporary species.

Most of the ancient plants have become coal, petroleum or natural gas as a result of geological metamorphosis over millions of years.

Only a small portion of them survive in the form of fossilized remains.

These give important data for understanding plant evolution, historical botany and plant geography.

They also provide direct or indirect clues on the ancient environment and palaeo-climate. In order to explore their chemical composition, scientists use a method known as chemical thermal cracking.

The CAS group has discovered some of the newly identified chemical compounds feature bio-activities against wood-decaying fungi.

Based on these findings, the researchers speculate the Pliocene pine specimens can keep themselves intact in the fossilized form. Some common components shared by the remains of the Pliocene and modern pines are capable of maintaining their own chemical stability.

The researchers also found the chemical composition of some compounds contained in the Cretaceous gingko fossils share some similarities with that of certain modern gingko tissue.

This suggests the natural products derived from the fossil's vermifuge, anti-oxidants and protective waxy wrapping, very probably have played a critical role in the good preservation of the fossil remains.

(China Daily November 17, 2004)