They also separated out the DNA from the bacteria and analyzed its composition using a technique called high-resolution secondary ion mass spectrometry; the isolated DNA contained arsenic.

然后他们从细菌中提取出dna，利用高解析二次离子质谱技术分析了其中的化学组成，发现DNA中也含有砷。

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Are more likely to achieve weight maintenance, have a healthier body mass and composition.

更有可能保持体重并具有更健康的体重和体成分。

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Estimate your body composition: Waist circumference and body mass index.

评估你的身体构成指数：腰围和体重指数。

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Well that process of control to maintain a constant environment inside our body, whether it's an environment of constant mass or constant composition, or constant temperature, is called homeostasis.

这个控制过程维持着,体内环境的恒定,不论是内环境中物质的量的稳定,或者成分的稳定,或温度的稳定,这种状态叫做内稳态

耶鲁公开课 - 生物医学工程探索课程节选

These new data, combined with the most recent estimates of its mass, allowed the researchers to infer its chemical composition.

BBC: Oddballs: The strange worlds beyond our Solar System

Buchholz, a physicist and a nuclear engineer, is an expert at something called accelerator mass spectrometry, an extraordinarily precise method of determining the chemical composition of materials.

FORBES: Magazine Article

Using a combination of modern physics tools--including three-dimensional, high-resolution X-ray, radiocarbon dating with accelerator mass spectrometry, and infrared spectroscopy--the researchers analysed the tooth to determine the age and composition of a resinous filling detected inside.

UNESCO: Basic Sciences