We'v e shown that learning optimism prevents depression and anxiety in children and adults, roughly halving their incidence over the next 2 years.

研究证实，乐观可帮助儿童和成人,预防抑郁和焦虑，使未来两年的发病率降低一半。

哈佛公开课 - 幸福课课程节选

So the square root of n squared r e over r h.

这里的n值是什么呢？

麻省理工公开课 - 化学原理课程节选

s We are back over to E as a function of n, l, m and s, only we got there through this other torturous route.

我们回到将E作为函数n，l和，只要我们解决了这个烦人的路径。

麻省理工公开课 - 固态化学导论课程节选

And we can simplify this expression as saying negative e squared over 4 pi, epsilon nought r squared. Epsilon nought is a constant, it's something you might see in physics as well.

也会遇到它,在这里，你可以就把它,理解为一个转换系数,我们需要做的。

麻省理工公开课 - 化学原理课程节选

So we can figure out the energy of each photon emitted by our UV lamp by saying e is equal to h c over wavelength.

所以我们可以计算出,每个从紫外光源射出的光子,也就是e等于h乘以c除以波长。

麻省理工公开课 - 化学原理课程节选

I know the energy in this first pair would equal -e^2 That is just going to equal minus e squared over 4 pi epsilon zero r naught.

我们明白第一对的能量将会等于,等于,/4πε0，R圈。

麻省理工公开课 - 固态化学导论课程节选