The interval is two mass units because these isotopes of the elements differ by two neutrons . 因为这些元素的同位素相差两个中子，所以其间隔为两个质量单位。
It is seen that the points representing stable isotopes define a rather narrow stability region . 可以看到，表示稳定同位素的那些点，构成一个很窄的稳定性区域。
It is useful to introduce a shorthand notation to facilitate the identification of various isotopes . 为了便于区别各种不同的同位素，引进简化的符号是很有用的。
In certain fusion processes, among nuclei of the hydrogen isotopes, neutrons of high energy are liberated . 在氢同位素原子核中的某些熔合过程中，会释放出高能中子。
Its most durable isotope survives only about 200, 000 years-a minute span on a stellar scale . 最持久的同位素只能存在大约二十万年--这在恒星的尺度上是一个很短的时间。
An obvious restraint in the use of isotope ratios results from the need to employ mass spectrometers . 使用同位素比值法有着一个明显的局限因素，就是要用质谱仪进行分析。
Isotopic studies from geothermal fields indicate that about 95% of the thermal fluid from steam wells is meteoric in origin . 地热田油同位素研究证明：蒸气井热流体的95左右是大气降水成因的。
Ordinarily, this mixture means little because the various isotopes are almost indistinguishable in most of their properties . 在一般情况下，这种混合是无所谓的，因为各种同位素在它们的主要属性上几乎是无法区别的。
Did you carbon - date the ink ? - of course , 你用炭同位素法测定过墨迹了吗？当然了
