这个词是什么意思？
Short-lived elementary particles found in cosmic radiation or produced from nuclear disintegration. Their mass is between that of protons and electrons and they can be negative, positive, or neutral. pi-Mesons (pions) are heavier than mu-mesons (muons) and are proposed for cancer radiotherapy because their capture and disintegration by matter produces powerful, but short-lived, secondary radiation.
中文名称索引；定义为 MeSH 英文原文，尚未逐条译审。MESH:D008651 · MeSH 2026。
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