As soon as the plants or animals die , the uptake of carbon - 14 will cease and the amount of carbon - 14 will decrease with time due to radioactive decay . the half - life of carbon - 14 is about 5 , 730 years 但当植物和动物死去,他们便会停止吸取碳- 14 。碳- 14的份量因衰变会随时间而减少,每经过一个半衰期(即大约5 , 730年) ,含量便会减半。
The hall - life measurement of long - lived radio isotopes , cross section measurement of nuclear reaction , searching for super heavy elements , cosmic study and solar neutrino detection are the main components which have been discussed 包括放射性核素半衰期的测定、核反应截面的测量、超重元素的寻找、宇宙射线和太阳中微子性质等方面的研究工作。
Our key insight was the realization that different xenon isotopes in our oklo sample were created at different times ? following a schedule that depended on the half - lives of their iodine parents and tellurium grandparents 我们的关键性认知是理解到,欧克陆标本中各种氙同位素是在不同时间生成的,时程表取决于它们的母元素碘和再上一代元素碲的半衰期。
( 2 ) influence of the promoter and upstream region on expression of cry id was tested . firstly , the pcr products of cry id promoter and its upstream were obtained followed by the construction of shuttle plasmid containing cryld - lacz 尽管cry1dmrna比cry1abmrna的半衰期更长,但cry1d和cry1ab转录时间和转录量的差异是导致其表达量差异的重要原因。
Most of earth ' s internal heat is generated by four long - lived radioisotopes ? potassium 40 , thorium 232 , uranium 235 and uranium 238 ? that release energy over billions of years as they decay into stable isotopes 地球内部的热能主要来自半衰期较长的四种放射性同位素钾40 、钍232 、铀235与铀238 ,它们在几十亿年来逐渐衰变成稳定的同位素,同时释放能量。