Each radionuclide has a characteristic half - life . the half - lives of radionuclides may vary from millionths of a second to millions of years 每种放射性核素都有其特定的半衰期，由几微秒到几百万年不等。
Each radionuclide has a characteristic half - life . the half - lives of radionuclides may vary from millionths of a second to millions of years 每种放射性核素都有其特定的半衰期，由几微秒到几百万年不等。
It is well - known that the cited half - life is a particular parameter to evaluate the degree of ageing of periodicals or magazines 摘要在期刊学术质量的评价指标中用来测度期刊老化程度的指标被引半衰期有其特殊性。
The eliminative speed also had difference in different tissues . t1 2b was the highest in the spleen , then in the liver and kidney 稀土进入组织后消除速度也因组织不同而有所差异，消除半衰期以脾最高、其次是肝和肾。
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。
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（放射性）的半衰期物质完全停止存在。
Trace amounts of natural radioactive materials , such as uranium , thorium and potassium with half - lives of up to one billion years , exist in soil 泥土中含有微量的铀、钍和钾等天然放射性物质，这些放射性同位素的半衰期可以长达10亿年。
Trace amounts of natural radioactive materials , such as uranium , thorium and potassium with half - lives of up to one billion years , exist in soil 泥土中含有微量的铀、钍和钾等天然放射性物质，这些放射性同位素的半衰期可以长达10亿年。
Since the half - lives of neptunium - 237 and its daughter radionuclides are relatively short comparing to the age of the earth , these radionuclides are not present in the earth nowadays 由于- 237及其子体核素的半衰期远低于地球的年，它们现已不存在于地球上。相反，
After one half - life , the level of radioactivity of a radioactive material is halved , after two half - lives , it is reduced to one quarter and so on 1 , 260 , 000 , 000年每经过一个半衰期，放射性物质的放射性便会剩下一半，经过二个半衰期，放射性便会剩下原先的四分之一，馀此类推。
