这个词是什么意思？
A trivalent radioactive element and the prototypical member of the actinide family. It has the atomic symbol Ac, and atomic number 89. Its principal isotope is 227 and it decays primarily by beta-emission.
中文名称索引；定义为 MeSH 英文原文，尚未逐条译审。MESH:D000186 · MeSH 2026。
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