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汉语拼音：tóng wèi sù

原子序数（质子数）相同而质量数（中子数）不同的原子互为同位素。它们的化学性质几乎相同，在元素周期表中占同一位置。如氯有两种同位素，原子序数均为17，但质量数分别为35和37。

1. 同一元素的质量数不同的各种原子互为同位素。同位素的原子序数相同，在元素周期表上占同一位置。同位素在原子核中的质子数相同，中子数不同，如氢有氕、氘、氚三种同位素。

• Another result of the widespread adoption of PCR was that radioisotopes would no longer be used in DNA-based forensic investigation.

  PCR的普遍采用的另一个结果是放射性同位素不再用于基于DNA的法庭调查。

• It quickly became clear, however, that the isotopic composition of meteorites differed not at all from that of the Earth itself.

  然而事情很快清楚了，陨石中的同位素比例与地球自身没有什么不同。

• Accelerators are also used for radioisotope production, cancer therapy, Biological sterilization, and one form of radiocarbon dating .

  加速器也用于制造放射性同位素、治疗癌症、生物消毒及放射性碳定年。

• Being a noble gas , it resists chemical bonding with other elements and is thus easy to purify for iso topic analysis.

  由于氙是惰性的，不易与其他元素产生化学键，因此很容易纯化以进行同位素分析。

• There was a small release of radioactive steam at Three Mile Island in 1979, and there have also been a few releases at Fukushima Daiichi.

  1979年三里岛核电站事故中便是有少量带放射性同位素的蒸汽泄露。

• I'm digging on the isotopes, this metaphysics shit is dope, and if all this can give me hope, you know I'm satisfied.

  我在吸食同位素，这种形而上学的狗屎是毒品，如果这些能给我希望，你知道我很满意。

• I should say the uranium-lead dating has been range for quite a while. But there have been a quite refine them.

  同位素铀元素标记已经使用了很长时间，但是有对他们定义，我会稍微讲解几分钟。

• The trick they used to do this was to look at the isotopic composition of the oxygen in the wood of local trees.

  他们所使用的办法是观测当地树木的木材中的氧同位素组成（isotopiccomposition）。

• Yet Australia has problems of its own with its single, albeit newish reactor, and has recently been importing isotopes from South Africa.

  尽管澳大利亚唯一的反应堆还是较新的，但仍存在不少问题，最近澳大利亚一直在从南非进口同位素。