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蛋白质是生命活动的物质基础。氮是组成蛋白质的主要元素,它占蛋白质含量的16—18％,也是细胞质、细胞核和酶的组成部分,因此氮素与其它元素相比,更多地限制着生物的生命,被人们称之为生命元素。空气中大约有79％的氮气(N_2),可惜N_2不活泼,不能被植物直接利用,而使植物常常感到氮源缺乏。氮素循环自然界中的氮素,处在一个无限反复的循环过程中。大气中的N_2,通过光化学和闪电,使一部分分子氮破裂、氧化,形成硝酸根离子(NO_3~-),这些NO_3~-融汇在大气云雾中,又常随雨水降到地面,供植物吸收。这个过程只能
Protein is the material basis of life activity. Nitrogen is the main element of the protein, which accounts for 16-18% of the protein content, and is also part of the cytoplasm, nucleus and enzyme, so that nitrogen is more limited to living creatures than other elements and is called For the life element. About 79% of the nitrogen in the air (N2), unfortunately N_2 is not active, can not be directly used by plants, leaving plants often feel the lack of nitrogen. Nitrogen circulates nitrogen in nature in an infinitely repetitive cycle. N_2 in the atmosphere, through photochemistry and lightning, ruptures and oxidizes part of the nitrogen molecules to form nitrate ions (NO_3 ~ -). These NO_3 ~ - are dissolved in the atmospheric cloud and often drop to the ground with rainwater, which is then absorbed by the plants . This process can only