1. 拉东：而且引入了可数可加集合函数的概念(定义于勒贝格可测集类上),指出这些函数是定义在集合类上的有界变差函数.正是因为对于有界变差与可加性概念之间联系的考察,使得J.拉东(Radon)作出了更广的积分定义,

2. 氡气：一个联合国委员会说,有越来越多的证据显示,现代民居住房内普遍存在的放射性气体氡气(Radon)有导致肺癌的危险.

3.

3. 镭射气,氡：helium 氦 | radon 镭射气,氡 | graphite 石墨

1. 氡
    Radon is a radioactive element in the form of a gas.

radon

1. a radioactive gaseous element formed by the disintegration of radium
    the heaviest of the inert gasses
    occurs naturally (especially in areas over granite) and is considered a hazard to health

    Synonym: Rnatomic number 86