商业机会有半衰期，就像铀一样。
然而，如果半衰期增加，情况会改变。
However, if the half-life is increased, the situation changes.
这种放射性元素半衰期约为5700年。
This radioactive element has a half-life of some 5, 700 years.
在英国，官方反对使用核能的半衰期很短。
THE half-life of official opposition to nuclear power in Britain has been very short.
半衰期实际上是,一半反应物消失的时间。
So, the half-life is just the time that it takes for half of the reactants to disappear.
放射性碘的半衰期为八天，几周内自然衰变。
Radioactive iodine has a half-life of eight days and decays naturally within weeks.
现在我们看看，这个一阶反应的半衰期。
Now, we also can usefully look at the half life, in this case, in the case of first order kinetics.
碘-131的半衰期为8天，对人身健康危害相当大。
Iodine-131 has a half-life of eight days and is quite dangerous to human health.
碘131有八天的半衰期，这意味着每八天其能量就下降一半。
Iodine 131 has a half-life of eight days, meaning that every eight days it loses half its strength.
而更危险的甲基汞(可损伤神经)的半衰期是44天。
The more dangerous methyl mercury, known to damage nerves, has a half-life of 44 days.
在一个宇宙中，原子在第一个半衰期中衰变了，于是你有了一只前猫。
So in one universe, the atom decays within the first half-life, and you have an ex-cat. Or ex-qat.
铀，碘，铯等元素在一定的半衰期内都可以释放出上述射线。
These rays are emitted during the decay of certain versions of uranium, iodine, cesium and other elements.
长期以来，对人体健康的一大威胁就是铯137，它的半衰期为三十年。
Over the long term, the big threat to human health is cesium-137, which has a half-life of 30 years.
很多情况下有必要，定义一个称为半衰期的量，这个量很有用。
In lots of cases, it's useful to define what's called a half life. It's just useful.
光衰小(其亮度半衰期)2000个小时老化测试光衰小于2%。
Light failure small (its brightness half-life) 2000 hours ageing test light failure is less than 2%.
服用稳定的碘元素会阻止危险碘同位素的摄入，碘同位素的半衰期仅为八天。
Taking stable iodine as a pill blocks the uptake of the hazardous radioisotope, which has a half-life of 8 days.
氚聚集在核反应堆的冷却水中，通常以微量排放到环境中，其半衰期为12年。
It accumulates in the cooling water of nuclear reactors and is often vented in small amounts to the environment. Its half-life is 12 years.
这里所指的半衰期是现存原子的一半发生衰变或爆炸所消耗的时间。
By that is meant the time which elapses before half of the existing atoms have disintegrated or exploded.
但碘- 131则不同，它的半衰期是八天，意味着它需要数月时间才会完全消失。
However, iodine-131 has a short half-life of eight days, which means it will decay away completely in the environment in a matter of months.
氮16的危险只针对于核电站工人和机器操作者而存在，因为它的半衰期只有七秒钟。
The danger of nitrogen-16 is an issue only for plant workers and operators because its half-life is only seven seconds.
而且钚元素的半衰期非常长，因此危险性的发射影响将会持续成千上万年。
Plutonium also breaks down very slowly, so it remains dangerously radioactive for hundreds of thousands of years.
更妙的是，显然人们可以用放射性作为时钟，用衰变系列的半衰期计算出岩石的年龄。
Better still, it became apparent to him that one could use radioactivity as a clock, with the half-life of a decay series enabling us to calculate the age of a rock.
要知道，核废料的半衰期是100000年——而英 国的巨石阵仅有四千年的历史。
It is often said that nuclear waste has a half-life of 100, 000 years…it is worth remembering that Stonehenge was built only 4, 000 years ago.
与放射性一样，故事有一个半衰期-换言之，就是新推荐的故事从首页到被下放的周期。
As with radioactivity, stories have a half-life-in other words a period by which half of newly promoted stories are relegated to a nether page.
不是，对“水合三氯乙醛”有较高耐药能力的人，它的半衰期仅为4个小时。
No, Chloral Hydrate has a half-life of only 4 hours in people with a high tolerance.
这座城市面临的最大问题就是处理铯—137，这是一种半衰期为30年的放射性同位素。
The city's challenge, chiefly, is to dispose of cesium-137, a radioactive isotope with a half-life of 30 years.
这座城市面临的最大问题就是处理铯—137，这是一种半衰期为30年的放射性同位素。
The city's challenge, chiefly, is to dispose of cesium-137, a radioactive isotope with a half-life of 30 years.
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