The rate equations for a continuous four level laser are solved in this letter, taking into account the finite lower level lifetime and the crystal field splitting of the laser levels.

在考虑了有限的下能级寿命和激光能级与晶格场的相互作用的基础上，对四能级激光的速率方程组进行了求解。

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There are cells within your body that are always in the process of division and forming new cells, and sometimes this is for a tissue where cells only have a finite lifetime.

你体内的一些细胞,始终在不断分裂,并生成新的细胞,很多时候,是在一些细胞寿命有限的组织中

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