单词	carbon 13
释义	carbon 13 noun : an isotope of carbon of mass number 13 that constitutes about ¹/₇₀ of natural carbon and is used as a tracer especially in spectroscopy utilizing nuclear magnetic resonance Example Sentences Recent Examples on the Web Blue = winter and low carbon 13/low bone cell density. Jennifer Ouellette, Ars Technica, 23 Feb. 2022 Yellow = summer and high carbon 13/high bone density. Jennifer Ouellette, Ars Technica, 23 Feb. 2022 Carbon has two stable isotopes, measured as either carbon 12 or carbon 13. Ashley Strickland, CNN, 17 Jan. 2022 Recent separate findings indicate that plant leaves receiving more light have a higher density of veins, as well as a higher ratio of a naturally occurring isotope called carbon 13. Rachel Nuwer, Scientific American, 1 Apr. 2021 Chemically, carbon 14 behaves exactly like its stable siblings (carbon 12 and carbon 13), allowing plants to absorb it during photosynthesis and then pass it up the food chain. Scott Hershberger, Scientific American, 4 Aug. 2020 So researchers compare the amount of carbon 14 with the levels of carbon 12 and carbon 13 to determine how much time has passed since an organism perished. Scott Hershberger, Scientific American, 4 Aug. 2020 This means that regions that once harbored photosynthetic life contain slightly lower amounts of carbon 13 than sterile areas. Peter Byrne, Quanta Magazine, 24 Apr. 2014 See More Word History First Known Use 1936, in the meaning defined above
随便看	macromesentery macromolecular macromolecule macromolecules macron macronecteses macronectesses macrons macronuclear macronucleate macronucleated macronuclei macronucleus macronucleuses macronutrient macronutrients macroorganism macrophage macrophages macrophagic macrophagous Macrophoma macrophotograph macrophotographies macrophotographs

英语词典包含469781条英英释义在线翻译词条，基本涵盖了全部常用单词的英英翻译及用法，是英语学习的有利工具。