同位素

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.

凭借这份资料和进一步的分析，朗布尔、研究论文的第一作者贝克及同事们今天在《科学》杂志上提出了如下的推测：在地球早期的历史上，火山爆发将大量的二氧化硫气体喷射到空中，太阳的紫外线将其分解，产生了奇特的硫同位素比值，这种硫随雨降下，积存于海底沉积层中；一旦到达海底，海底各处的地热出口所产生的温度过高的水把硫加热成硫化物；最终含有镍的岩浆从地幔中涌出，跟硫化物结合形成硫化镍，并将硫化镍包裹在一种叫做"科马提岩"的火山岩中。

Berkelium, for example, was first synthesized at the University of California, Berkeley.

但到目前为止所生成的超重元素及其同位素的寿命都很短，大多在秒和毫秒的量级。

For example, H, atomic weight of 100,794 hydrogen, carbon FC atomic weight of 1201, the atomic weight of oxygen O for 1594, Copper Cu for F63546 and so on. F history, had also used the other two kinds of "benchmarks", and there have been two kinds of scales used in parallel .1803 years, J Dalton published the first atomic table, the hydrogen-quality of the original F son as a "benchmark "requiring H, atomic weight is 1. In 1826, JJ Berzelius Tony F are presented to the quality of 116 oxygen atoms O as a" baseline "(scheduled for O, E atomic weight 16), which is has been in use to 1961 "Oxygen unit." 1929, found that the oxygen in nature, in addition to the greatest abundance of 16O, there are a small amount of slightly heavier 17O and 18O two kinds of isotopes, and the different sources of oxygen, its composition is slightly different.

例如氢H的原子量为100794，碳FC的原子量为1201，氧O的原子量为1594，铜Cu为F63546等。F历史上，还曾用过另外两种"基准"，并且有过两种标度并行使用。1803年，J道尔顿发表的第一张原子量表，把氢原F子的质量作为"基准"，规定H的原子量为1.1826年，JJ贝F采利乌斯提出，以氧原子O质量的116作为"基准"（定O的E原子量为16），这就是一直沿用到1961年的"氧单位"。1929年发现，自然界中的氧，除丰度最大的16O以外，还有少量稍重的17O和18O两种同位素，并且不同来源的氧，其组成也稍有不同。

Biogenetic gas;origin of hydrogen;biochemical action;hydrogenase;isotopic composition

生物气；氢的来源；生物化学作用；氢化酶；同位素组成

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.

由根往茎叶，硅的含量与同位素组成呈规律性变化。为研究植物中硅的吸收、搬运与沉淀机制，探讨植物在硅的生物地球化学循环中的作用提供依据。

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当前的河流有机质生物地球化学研究中仍起着非常重要的示踪作用。

The aim of the investigation is to build up a more precise stritigraphic sequence and a corresponding environmental index based on a combination of evidence in the research of petrology, biostratigraphy, paleomagnetism, sedimentation, and isotope.

在结合岩石及生物地层、古地磁、沉积环境、碳氧同位素等研究方法的综合证据基础上建立较精确的地层层序及其相对应的环境指标。

A geological time scale based mainly on both biostratigraphy and radiometric dating created stratigraphic refulgence, but at the cost of lowered accuracy and preciseness and weakened function of serving the human society.

以生物地层学为基础并与放射性同位素定年技术相结合建立的、以百万年为计时单位的地质年代表既创造了地层学的辉煌，也在一定程度上降低了地质学对精确数字定年的不懈追求和为人类社会服务的功能。

This paper presents an integrated and comprehensive Lower Triassic sequence of Chaohu to serve for a standard regional stratigraphical sequence, based upon up to date achievements in the studies of lithostratigraphy, biostratigraphy and carbon isotope stratigraphy at three sections in the area.

根据巢湖地区3条代表性下三迭统剖面的岩石地层、生物地层和碳同位素地层的最新研究成果归纳出本区早三迭世综合地层序列，作为区域地层对比研究的标准。

By summing up the cyclicity, rock association and occurrence of volcanic rocks with their overlying and underlying contact relations and forming environment, and concerning the research results of isotope chronology and biostratigraphy, the Yixian formation of the working area may be subdivided into four members.

综合火山岩的旋回性特徵，岩石组合、岩石产出特徵，不同岩石组合的上、下接触关系和岩石形成环境的分析结果，结合同位素年代学及生物地层学的研究成果，区内义县组被划分成了4个岩性段。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。