This paper presents a determination method of specific activity for uranium isotope in rocks, soil, water and thoriumisotope in rocks using 232u as a tracer isotope.
本文介绍了用(232u)作示踪同位素，测定岩石、土壤、水体中铀同位素及岩石中钍同位素比活度的方法。
2
In this case the geologists drilled into the stalagmites and estimated their age from the way that uranium decays into an isotope of thorium.
地质学家在石笋上钻孔，使用铀衰变成钍的同位素的方法确定它们的年龄。
3
Calculations suggest, for instance, that in the nucleus of the isotopethorium-229 is a transition that should emit ultraviolet rays.