The most common isotope of oxygen, for example, has an atomic weight of 16, but there are also rarer isotopes with weights of 17 and 18, caused by additional neutrons in their nuclei.

例如很常見的同位素氧，原子重量是16农村熟女乱子a，但是還有更為稀少的重量為17和18的同位素久久青草国产免费频观日本，這是因為它們的原子核中有額外的中子。

In determination of atomic weight and isotope certified reference materials preparation, isotopic abundance almost is determined by this method.

在原子量的精確測量和同位素標(biāo)準(zhǔn)物質(zhì)的研制工作中亚洲人人看，一般采用此方法對元素同位素豐度進(jìn)行定值视频黄片在线，測量儀器多采用表面熱電離質(zhì)譜計。

YANG Kui ,ZHOU Ling,WANG Yan-zhenThe Nationbal Center for Isotope of Engineering and Technology,ChinaInstitude of Atonic Energy,Bei-jing 102413,China

單位：中國原子能院國家同位素工程技術(shù)研究中心欧美一级a爱片在线播放，北京 102413關(guān)鍵詞：雙抗夾心；免疫PCR国产三级电影视频；人促甲狀腺激素TSH

In order to find the difference of the isotopic composition of different organic compounds before and after complexation, the autogamy standard sample is performed by molecular sieve adsorption to study the variation of the isotope compositions of n-alkanes, isoalkanes and cyclanes.

通過對自配標(biāo)準(zhǔn)樣品進(jìn)行S分子篩吸附試驗看免费刺激欧美作爱大片，測定了用5分子篩吸附法分離前后正構(gòu)烷烴360天天色秋霞、異構(gòu)烷烴和環(huán)烷烴碳同位素值，探討試驗前后碳同位素值的變化。

Analysis shows that the effects of the laser spontaneous axial magnetic field and the laser spontaneous transverse magnetic field are opposite, and there is competition between them in the process of isotope separation.

分析認(rèn)為，激光等離子體中的自生軸向磁場和環(huán)形磁場在同位素的分離過程中可能起著相反的作用，二者相互競爭。

All the volcanic rocks present younger K-Ar age (less than 5Ma), which can be termed as Cenozoic rocks. In general speaking, volcansim can be dividied into two eruptive stages. In the first stage, volcanic rocks for Pliocene epoch (4. 4-5Ma) consist of basanite and tephrite, which distributed on Mt. Crater, Cape Bird, and southern bank of Bonney Lake; In the second stage, volcanic rocks for Quaternary (less than 1 Ma) are mainly composed of latite, which are distributed on Cape Rodeys and Cape Evens.On the basis of geochemical data such as major elements, trace elements , rare earth elements, isotope, microprobe analysis, combined with main achievement taken by previous researcher in this area, conclusions are drawn basically as follows

所噴發(fā)的火山巖K-Ar年齡值均小于5Ma，為新生代火山巖日韩papapa，大體上可以分為兩個噴發(fā)階段，第一個階段為上新世火山巖(年齡值為4.4-5.0Ma)国产a片播放网址，主要由碧玄巖和堿玄巖組成一区二区亚洲，分布于羅斯島上的克雷克特山欧美在线亚洲一区二区欧美、鳥角和泰勒谷的博尼湖南岸；第二階段為第四紀(jì)火山巖(年齡值均小于1Ma)野狼网址，主要由安粗巖組成成Aⅴ人视频在线l免费观看，分布于羅斯島上的羅德角和伊萬思角，通過主要元素www.手机无码视频、微量元素国产在线无码全黄、同位素結(jié)合電子探針以及前人的研究成果国产原创AV在线，我們大體上可以得出如下認(rèn)識

Armed with this information and further analyses, Rumble, lead author Bekker, and colleagues propose the following scenario today in Science . Early in Earth's history, volcanic eruptions spewed massive amounts of sulfur dioxide into the atmosphere, where UV sunlight broke down the gas and created the odd sulfur isotope ratios. The sulfur descended with the rain and accumulated into sedimentary beds on the sea floor. Once there, superheated water from geothermal vents at various locations on the sea floor cooked the sulfur into sulfide. Finally, nickel-bearing magma welled up from Earth's mantle, combining with the sulfide to form nickel sulfide and encasing the compound inside volcanic rock called komatiite.

憑借這份資料和進(jìn)一步的分析，朗布爾欧美日韩免费一区中文字幕、研究論文的第一作者貝克及同事們今天在《科學(xué)》雜志上提出了如下的推測：在地球早期的歷史上www.色呦呦，火山爆發(fā)將大量的二氧化硫氣體噴射到空中日韩AⅤ在线高清免费看，太陽的紫外線將其分解美女扒开下边喷水黄网站，產(chǎn)生了奇特的硫同位素比值，這種硫隨雨降下日韩最大的黄色网站，積存于海底沉積層中；一旦到達(dá)海底免费观看国产线上视频，海底各處的地?zé)岢隹谒a(chǎn)生的溫度過高的水把硫加熱成硫化物人操人AV；最終含有鎳的巖漿從地幔中涌出，跟硫化物結(jié)合形成硫化鎳亚洲色一色噜一噜噜噜性色av，并將硫化鎳包裹在一種叫做"科馬提巖"的火山巖中成人无码秒播在线观看网站免费视频。

The understanding of biogeochemical cycle of hydrogen, oxygen, carbon, nitrogen, and sulfur elements in nature ecosystem have increased substantially in the past two decades owing to the improvement of gas isotope ratio mass spectrometer and the wide application of isotopic studies with these elements.

近20年由於「氣相同位素比值質(zhì)譜儀」的改良和氫、氧、碳色欲综合视频一区二区在线观看、氮和硫等穩(wěn)定同位素的廣泛研究中文亚洲日韩国产精品，穩(wěn)定同位素的研究技術(shù)已實質(zhì)增加我們對於這些元素在自然生態(tài)系中生地化循環(huán)的瞭解。

Systematical variations of silica contents and silicon isotope compo- sitions are observed from their roots to stem to leaves, which provide us reliable evidences for studying the mechanisms of adsorption, transpor- tation and precipitation of silicon in plants, as well as the role of plants in silicon biogeochemical cycle.

由根往莖葉性与色欧美视频在线播放网站，硅的含量與同位素組成呈規(guī)律性變化99黄aaa。為研究植物中硅的吸收、搬運(yùn)與沉淀機(jī)制黄色网站操逼片，探討植物在硅的生物地球化學(xué)循環(huán)中的作用提供依據(jù)男干女黄色视频。

In addition, carbon and nitrogen isotope and its ratio was important indicator in the riverine biogeochemistry study.

另外碳氮同位素及其比值在當(dāng)前的河流有機(jī)質(zhì)生物地球化學(xué)研究中仍起著非常重要的示蹤作用。