碳定年

Nature, most elements have two or more isotopes, the same kinds of elements in the quality of the various isotopes of different, but the types and proportion constant (except for radioactive elements). In 1961, the carbon content of the most abundant in nature, a kind of isotope, carbon-12 atom of a quantity and quality of C as a 12 mass units to it as "benchmarks" for all isotopes of an element according to the average abundance The ratio of the benchmark is the atomic weight of this non-prime, that is listed in the periodic table of atomic weights.

自然界中大多数元素都有两种或更多的同位素，同种元素的各同位素质量不同，但其种类和比例是恒定的。1961年，把碳在自然界含量最丰富的一种同位素，碳12的一个原子的质C量定为12个质量单位，把它作为"基准"，某种元素的所有同位素按丰度的平均值与基准之比，就是这种无素的原子量，即元素周期表列出的原子量。

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。

The company has 320 staff,39 medium and senior technicians , 2 magnesite carbon quality of production line,2 unshaped refractories of production line,with annual production of shaping refractories 50000 tons,unshaped refractories 30000 tons.

我公司现有员工320人，中、高级科技人员39人，拥有现代化的镁碳质定形生产线2条，不定形制品生产线2条，年生产能力为定形制品5万多吨，不定形制品3万多吨。

Do you know, i need you to come back

你知道吗，我需要你回来

Yang yinshu、Wang xiangsheng、Li decang,The first discovery of haemaphysalis conicinna.

1〕 杨银书，王祥生，李德昌。安徽省首次发现嗜群血蜱。