n.周期性；周期數(shù)
Periodicity of nuclear properties began to show up. 原子核性質(zhì)的周期性開始顯示出來了。
The numbers are not intermixed accidentally but are subject to regular periodicity. 這些數(shù)字不是雜亂無章的、不是偶然出現(xiàn)的,而是有規(guī)律的、周期性的。
非周期性
n.非周期性(非調(diào)諧性)
