radioactive half life
放射性物质的半衰期
The time required for half the nuclei in a sample of a specific isotopic species to undergo radioactive decay.
半衰期放射性样品的原子核经历一半放射性衰变所需要的时间
Half-life of radioactive element carbon-14 is 5730 year.
放射性元素碳-14的半衰期为5730年。
Radioactive substances will speed up their dissipation to such a degree that what had hundreds of years of half life will simply cease to exist.
放射性物质将加速其解体，使得还有好几百年（射性）半衰期物质完全停止存在。
Preliminary Basic and Clinical Studies on Positron Emission Tomography: The Study on Positron Emitting Radipharmaceuticals;
正电子发射断层（PET）基础与临床研究：短半衰期正电子放射性药物的研究
any of several radioactive gases that are isotopes of radon and are products of radioactive decay.
"几种氡的同位素的放射性气体,是放射性物质衰变的产物."
We can talk about the half-life of a radioactive isotope, and indeed we can measure and state very very precisely what that half-life is.
我们可以谈论放射性同位素的半衰期，我们确实可以非常准确地测量和描述半衰期是什么。
Because of the continuous decay, the quantity of radioactive material and the rate of emission of radiation decrease steadily.
由于连续衰变的结果，放射性物质的数量，辐射发射率都逐渐下降。
A radioactive, inert, gaseous isotope of radon, with a half - life of3.92seconds.
锕射气氡的一种放射性的，惰性的和气态的同位素，其半衰期为3。92秒
Exempt Items of Radioactive Substances
放射性物质的豁免物品
unsealed radioactive substance
非密封的放射性物质
radioactive recoi
放射性衰变引起的反冲
(the sending out of)rays and atomic particles from radioactive substances
（自放射性物质中放射出的）射线和原子粒子
The immediate product of the radioactive decay of an element.
继承元素某种元素放射性衰变的直接产物
Regulation of radiation protection for handling nonsealed radioactive material
GB11930-1989操作开放型放射性物质的辐射防护规定
radiation resulting from radioactive decay.
由放射性衰变产生的辐射。
contaminated clothing,eg by radio-active material
受污染的衣物（如受放射性物质污染）
radioactive decay with emission of carbon nuclei
碳核发射放射性衰变