When two or more elements combine and form a compound, a chemical change takes place.
当两种或两种以上的元素化合形成化合物时，发生化学变化。
2
This paper analyses characteristics of readers' information demand and change of compound library times from conception and characteristics of compound library.
从复合图书馆的概念和特点出发，分析了复合图书馆时代读者的信息需求特点和需求变化情况。
3
Objective To observe mainly the effect of the Chinese traditional medicine (compound Wenxin soup) on myocyte apoptosis and path-histology change in rabbits ischemia referpusion injury.