I specialize in measuring stable isotopes, things like carbon and helium and other stable isotopes.

我擅长测量稳定的同位素，如碳和氦以及其他稳定的同位素。

I injected the stable isotope carbon-13 carbon dioxide gas.

我往他们的袋子中注射了 含有稳定性同位素碳13的二氧化碳。

Stable isotopes in bone collagen and tooth enamel varies among mammals dependent on where they lived and what they ate.

稳定的同位素在骨骼的胶原蛋白或 牙釉质中因不同的哺乳动物而异这取决于它们住的地方和吃的东西。

Denied. All right, for ten points, What is the lightest element on Earth, with no stable isotope?

驳回。接下来十分题，地球上没有稳定同位素的最轻的物质是什么？

You see, the annual growth rings here show the presence of the stable isotope Nitrogen-15, which significantly comes from the oceans.

你看，这里每年增加的年轮显示出氮的稳定同位素：氮-15的存在这意味着这些氮来自于海洋。

And it turns out nitrogen atoms can have either seven or eight neutrons and remain stable—so nitrogen has what chemists call two stable isotopes.

氮原子可以有7到8个，某些氮原子比另一些氮原子拥有更多的中子，保持稳定的中子。因此氮原子含有化学家所说的两种稳定同位素。

Basically you are what you eat. And so when you study this -- stable isotopes -- you get an indicator of what the humans have been eating.

基本上可以说，吃什么，就是什么。所以在研究这个问题，也就是稳定同位素的时候，就可以得到线索，了解到人们吃过什么。

No element heavier than lead (number 82) has a stable isotope, and above number 92 (uranium) lifetimes are so short that these substances are almost non-existent in nature.

比铅（82号）更重的元素都没有稳定的同位素，在铀（92号）之后的元素寿命太短，以致于在自然界中几乎不存在。

So silver has two stable isotopes, one with a mass number of 107, which we'd call silver-107, and one with a mass number of 109, silver-109.

所以银有两种稳定同位素， 一种质量数为 107， 我们称之为 silver-107，另一种质量数为 109， silver-109。

Now you might be asking, if radioactive elements are always decaying in to more and more stable isotopes that are eventually no longer radioactive, why are they still around at all?

现在您可能会问， 如果放射性元素总是衰变成越来越稳定的同位素，而这些同位素最终不再具有放射性， 那么为什么它们仍然存在呢？

Based on a study of stable isotope signatures found in its teeth and bones, which can help tell us what an animal ate, it looks like Castoroides mostly ate freshwater plants, like water lilies, pondweeds, and sedges.

根据对其牙齿和骨骼中发现的稳定同位素特征的研究，这可以帮助我们了解动物吃什么，Castoroides 看起来主要吃淡水植物，如睡莲、池塘草和莎草。