isotope ratio
...元素;同位素比值 [gap=3236]ological sample; reference material; meteorite;biological sample; trace element; isotope ratio ...
sulfur isotope ratio
hydrogen isotope ratio
nitrogen isotope ratio
元素的同位素比值是元素中各同位素丰度之比。该元素的重同位素原子丰度与轻同位素原子丰度之比。由于同位素比值难以准确测定,因此样品的同位素比值通常用它与某一标准物质的同位素比值的千分差来表示。