一个很有用的量是反应的半衰期。

A very useful quantity is the half-time for the reaction.

youdao

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.

youdao

核反应堆完全熔解后，会释放出另一种危险物质铯- 137。铯- 137的半衰期为30年。

Cesium-137, with a half-life of 30 years, is another dangerous substance emitted in a full-scale nuclear meltdown.

youdao