元素周期表和原子核物理相关的一些常用的函数。
根据原子序数获得原子核的名称，并且为不同同位素提供latex表示输出。
其中117号和118号元素的汉字是存在的，并且已经收录在Unicode中，但是现在大部分的字体都不支持显示这两个字符，所以只好暂且使用偏旁表示了。
元素周期表数据来自于：微信元素周期表：专业版，以下是该开源代码的LICENSE。
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