地质年代通常是通过矿物中发现的各种放射性元素的衰变率来获得的。
Geological dates are usually obtained by using the rates of decay of various radioactive elements found in minerals.
根据保存这些化石的岩石层里铀衰变率的基础上所确定的年代，那次掉入洞穴事件发生在197.7万年前。
That fall into the cave happened 1.977 million years ago, according to dating based on the rate of decay of uranium in the rock layer that holds the fossils.
与三能级原子系统相比，四能级原子相干效应即可导致电磁感应透明的产生，也可产生电磁感应吸收现象，取决于控制光的强度和第四个能级衰变率的大小。
Compared with three-level atomic system, the atomic coherence effects in four-level can lead to EIT and EIA, which depend on the intensity of control light and the relaxation of the fourth level.
与三能级原子系统相比，四能级原子相干效应即可导致电磁感应透明的产生，也可产生电磁感应吸收现象，取决于控制光的强度和第四个能级衰变率的大小。
Compared with three-level atomic system, the atomic coherence effects in four-level can lead to EIT and EIA, which depend on the intensity of control light and the relaxation of the fourth level.
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