半衰期

239Pa has been identified by using observation and analysis of γ-rays of 239Pa and 239U as a daughter nucleus of 239Pa. The half-life of 239Pa was determined to be （106±30） min.

借助于239Pa和它的子体239U的γ射线观测和分析，鉴别了239Pa，测得239Pa的半衰期为（106±30） min。

The activity of thorium was measured by using a HPGe detector and a planar HPGe detector. 238 Th has been identified for the first time by measuring the growth and decay of the γ rays from its daughter nucleus 238 Pa.

使用两台高纯锗探测器测量了样品的γ射线活性，观测到了238Th的β－衰变子体238Pa的γ射线的生长、衰变行为，测定238Th的半衰期为9.4±2.0min

The decay of ~(99m)Tc source was used to verify experimentally that in the measurement of the number of atoms of a radioactive isotope in a sample at time t_0, the error introduced through the inaccuracy of its decay constant can be reduced to a much smaller value by the careful selection of the time of measurement or measurements of its radioactivity at around one life time (1/λ) after t_0 and doing the calculation.

本文用~(99m)Tc源的衰变实验证明了：在测量一个样品中在t_0时的一种放射性同位素的原子数时只需精心选择一次或多次测量其放射性的时刻在t_0后约该同位素的一个寿期(1/λ)，并进行计算，则由它的衰变常数或其半衰期(T1/2)的不准确性而引进的误差可以被降低到较小值。

Results of kinetic study of the degradation process of anthocyanins in Myrica rubra juice suggeste that the degradation process is a first order degradation kinetic process. As the increase of temperature and pH value, the half-life degradation of anthocyanins and activation energy for the thermal degradation decrease significantly. Under the same condition, the half-life of concentrate is significantly lower than that of the juice.

花色苷降解动力学数据的分析结果表明：杨梅花色苷热降解属动力学一级反应，随着pH值和温度的升高，杨梅花色苷降解的半衰期(t 1/2)和热降解活化能显著下降，即花色苷的降解速度增大；同一处理条件下，浓缩果汁的 t 1/2明显低于澄清汁。

Field residue decline of prochloraz in mushroom and soil was found to conform to exponential equation.

结果表明，咪鲜胺在蘑菇及土壤中的消解动态均符合负指数方程，半衰期分别为3.5d和20.3d；2，4，6-三氯苯酚在蘑菇中的残留量随时间的变化呈现先增后减的趋势，而其在土壤中的残留量则仅表现出增长的趋势。

Based on the comparison of the delayed neutron counter rate of known fission rate with the delayed neutron counter rate of a burst,a method to determine burst total fission number of burst reactor was built.

用长计数器测量已知裂变率的缓发中子计数率，然后用同一探测系统测量脉冲后的缓发中子计数率，探测系统的探测效率、缓发中子份额和缓发中子先驱核半衰期等参数均不变，从而建立起利用脉冲堆脉冲后的缓发中子衰减曲线确定脉冲裂变总数的方法。

The replacement of SF6 by refrigerant is under development. For example, R143a by AMC and FK by 3M Co. used as protection gas are both classified as HFC with short atmospheric lifetime and are easily to be decomposed into hydrofluoric acid, carbon monoxide and fluoric carbon monoxide at room temperature.

目前发展中的替代性保护气体以冷媒类为主，如澳洲AMC所采用的R134a及美国3M公司所开发的FK气体，两者都属於氟氢碳化合物，不过其半衰期短，即使在常温下，仍极易分解成氢氟酸、CO、COF2等，其中氢氟酸为有害物质，但因含量很少，且在高温下易与镁液反应，故对人体的为害很小。

Even Francium's most stable isotope, Francium-223 only has a half-life of 22 minutes.

钫的最稳定的同位素，钫-223也只有22分钟的半衰期。

Ozone decomposition rules in gaseity and aqueous solution, mainly the influence of temperature and pH value, are discussed in this paper.

该文研究了臭氧在气态和水溶液中的分解规律，主要研究了温度和pH值的影响，并获得了不同温度、pH值下臭氧分解的半衰期。

Half-Life 2 Lost Coast remains logically in favor of X1300 which always seems a lot better thanintegrated graphic solution.

半衰期2半条命逻辑仍然主张x1300其中似乎总是有很多优于综合图解。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。