DNA methylation shows chemical changes in a person's deoxyribonucleic acid,or DNA.

VOA: special.2009.11.24

You have a diversity in the chemical changes that occur as a result of any of those connections.

又有多样化的化学变化,这是那些物理连接的产物

耶鲁公开课 - 生物医学工程探索课程节选

Most chemical changes, most physical changes don't happen in isolated systems.

但是大部分的化学反应,并不是发生在孤立系统中的。

麻省理工公开课 - 热力学与动力学课程节选

So here are some spontaneous chemical changes Here's one.

这有一些自发进行的化学反应,这一个。

麻省理工公开课 - 热力学与动力学课程节选

That's very useful for things like chemical reactions where this constituent changes to this one.

对于化学反应之类的过程,这是非常重要的。

麻省理工公开课 - 热力学与动力学课程节选