| 1. | It has a half-life of about 41/2 billion years .
它的半衰期大约为45亿年。 |
| 2. | The half-life of francium is 22 minutes .
钫的半衰期是22分钟。 |
| 3. | A very useful quantity is the half-time for the reaction .
一个很有用的量是反应的半衰期。 |
| 4. | the half life of the uncharged pion is 6×s.
中性兀介子的半衰期为6秒。 |
| 5. | It is not necessary to wait until half of a sample has decayed in order to measure the halflife .
不必一直等到样品衰变一半之后才测量它的半衰期。 |
| 6. | By that is meant the time which elapses before half of the existing atoms have disintegrated or exploded .
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。 |
| 7. | It has a rather short half - life of 138 days
其半衰期很短，只有138天。 |
| 8. | Experimental study on half - life period of carotin in spirulina
螺旋藻中胡萝卜素半衰期实验研究 |
| 9. | Test method for electrostatic properties of plastic films . half - life method
塑料薄膜静电测试方法半衰期法 |
| 10. | Research on the relationship of citing half life and price index
引文半衰期与普赖斯指数之间的数量关系研究 |
