单词 | 六百万 |
释义 | 〔plutonium〕A naturally radioactive, silvery, metallic transuranic element, occurring in uranium ores and produced artificially by neutron bombardment of uranium. Its longest-lived isotope is Pu 244 with a half-life of 76 million years. It is a radiological poison, specifically absorbed by bone marrow, and is used, especially the highly fissionable isotope Pu 239, as a reactor fuel and in nuclear weapons. Atomic number 94; melting point 640°C; boiling point 3,235°C; specific gravity 19.84; valence 3, 4, 5, 6. See table at element 钚:一种天然地放射性银色超铀金属元素,存在于铀矿中,对铀元素进行中子轰击而人工制成。其存在周期最长的同位素是半衰期为七千六百万年的钸244,它是一种核辐射毒素,特别是能被骨髓吸收。尤其是其极具可裂变性的同位素钸239,被用作一种核反应燃料并用在核武器中。原子序数94;熔点640°C;沸点3,235°C;比重19.84;化合价3, 4, 5, 6 参见 element |
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