Sometimes second messengers collect signals from a variety of different receptor systems, translate them into one kind of internal change, and the cell then just has to know about that one thing changing.

第二信使分子能够收集,来自不同受体系统的信号,将它们转化为同一种细胞内在的变化,这样细胞就只需对一种变化作出反应

耶鲁公开课 - 生物医学工程探索课程节选

So, we have, we're interested in the change in internal energy for various experimental constraints.

我们感兴趣的是,在各种实验环境约束下内能的改变。

麻省理工公开课 - 热力学与动力学课程节选

And because there is an explicit relationship between u, delta u, q and w, you can always find the easy way to derive the change in internal energy or the heat or the work.

因为Δu，q和w之间,有明确的关系，一般来说,内能或热或功的变化,易于计算。

麻省理工公开课 - 热力学与动力学课程节选