查询词典 alkanes

Several main results on the evolutions of the life and environment on early earth are summarized as follows:(1) the oxygenation of surface environment didn''t cease until a stable stage for 0.4Ga appeared after 1.6Ga;(2) compared to the isotopic compositions of kerogens and coexisted carbonates, the differences between two can effectively carrier the signals from local environments and bio-assemblages;(3) multiple isotopic relationships between kerogens and individual alkanes in Proterozoic samples were observed, which would depend on the specific biogeochemical processes;(4) repeated biogeochemical changes were observed accompanying Neoproerozoic glaciations, which suggesting that environmental rather than evolutionary forces were driving the biogeochemical changes;(5) the bio-radiations after Neoproterozoic glaciations were definitely suggested by molecular and isotopic data to be at the early Cambrian and after the middle of Doushantuo deposition with different triggers for them.

研究获得以下重要认识：（1）古元古代地表环境的氧化可能一直持续到中元古代早期(约1.6Ga)，而在此之后的4亿年里则保持相对稳定；（2）相对于传统的干酪根和碳酸盐的碳同位素组成，二者之差则能更好反映区域环境的演化特征；（3）在元古代干酪根与单体烷烃类之间存在多种碳同位素组成关系；而其与不同的生物地球化学过程有关；（4）全球海洋生物地球化学特征随新元古代多次冰期出现循环波动，这显然为环境因子的驱动；（5）在新元古代大冰期之后，分子与同位素数据显示地球生命在陡山沱中后期和早前寒武纪出现两次大辐射，然而两次生命辐射的本质却是不同的。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。