The oxygen isotope ratio of the ocean changes as a great deal of water is withdrawn from it by evaporation and is precipitated as snow to form glacial ice.

随着大量的水通过蒸发被抽离，并以雪的形式沉淀形成冰川冰，海洋中氧同位素的比率就发生了变化。

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The isotope ratio is directly used for comparing oils or gases.

同位素比率直接用于比较各种石油或天然气。

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But the team found that on the Moon it was about 25 times that of the terrestrial chlorine isotope ratio.

但是研究团队发现在月球上氯的同位素的比率大约是地球上的25倍。

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The test, called a carbon isotope ratio test, can distinguish naturally produced from artificial testosterone.

NPR: Landis Facing Uphill Battle on Doping Charges

The most likely alternatives, butter and pig fat, were ruled out using a technique called isotope-ratio mass spectrometry, which measures the molecular weights of the chemicals in a sample.

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