There is a huge difference between the energies in the outermost shell and the inner shells, which tells you that it's unlikely that any electrons except those in the outermost shell are going to be active.

最外层和最里层所具有的能量,有很大差异，而这告诉我们有一点是不太可能的,那就是除了最外层的电子,别的电子都是应该是活泼的。

麻省理工公开课 - 固态化学导论课程节选

We did not yet have good methods for screening blood to look for HIV, we didn't have the ELISA technique that I--we talked about in section a few weeks ago and so there was a great concern that there might be other diseases that you'd be passing on from-- unknowingly from this subset of patients that you're isolating the vaccine from.

那时我们还没有一种好的方式,来从血液中筛查出HIV,也还没有ELISA技术,该技术我们在几周前的一个章节中谈到过,因此,那时仍存有,很大的担心,那就是你有可能,在不知情的情况下,被那些病人,感染上其它疾病,因为疫苗就是从他们身上提取出来的

耶鲁公开课 - 生物医学工程探索课程节选