radioactive series

radioactive-series的词性：
n.（名词）

1. A group of isotopes representing various stages of radioactive decay in which the heavier members of the group are transformed into successively lighter ones, the lightest being stable.
放射系：代表放射性衰变不同阶段的一组同位素，较重的元素连续地转化成较轻的元素，最轻的元素变得稳定