同位素

Lead has four stable isotopes: Lead 204, 206, 207, 208, but there are more than 20 kinds of radioisotopes.

铅在自然界中有4种稳定同位素：铅204、206、207、208，还有20多种放射性同位素。

High oxygen isotope temperatures of 650 to 695℃ were obtained when pairing quartz with such resistant minerals as garnet, zircon and kyanite, suggesting that the refractory minerals have preserved their oxygen isotope compositions acquired during eclogitization and only suffered much weaker retrograde metamorphism than the other minerals in the eclogite.

石英-耐熔矿物对氧同位素温度主要集中在650～695℃之间，表明耐熔矿物石榴石、锆石和蓝晶石在该区榴辉岩中相对其它矿物来说保存最好，退变质作用最弱，因此其氧同位素温度与峰期超高压榴辉岩相变质奈件基本一致。

This paper deals with and summarizes the research and importance of ductile shear zones and presents the future direction and aim for the research of the ductile shear zones around the world. Four aspects of studies of the ductile shear zones have been proposed in this paper as follows:(1) The stress environment including the mineral assemblages, deformation, stress-shearing parameters;(2) The major element sequence and activation under condition of stress;(3) The variations of trace elements and REE, their transportation distributions under strong natural deformation as well as variations of mineral crystal parameters, which can also control the element changes during the ductile deformation;(4) The relationship between element migrations, activation and stress, which will present the new evidences for the studies of dynamic diagenesis and mineralization as well as the studies of evolution of ductile shear zones developed in middle and low levels.(5) The analysis of elements and isotopes in mylonites on the micro-scale are crucial for the understanding of component migrations during the mylonization.

对韧性剪切带及其变形岩石的研究现状和研究意义进行系统的综述，提出了未来韧性剪切带及其糜棱岩的研究方向和目标：①系统研究糜棱岩中主要造岩矿物组合及其变形特征，计算剪切变形岩石的应力－应变参数，搞清韧性剪切带所处的应力应变环境；②系统研究韧性剪切带岩石在天然分强剪切应力作用条件下常量元素迁移机制及活化转移的应力排序问题；③系统研究剪切变形作用过程中岩石化学组成的微量和稀土元素变化，讨论强变形条件下岩石中微量元素活化和迁移规律，深入探讨微量元素迁移的动力控制，包括稀土元素配分变化的应力制约以及应变矿物晶格化学变化行为及其对其寄主的变形岩石元素在应变过程中迁移变化的制约和影响；④从理论上探讨天然强剪切应变条件下岩石中组分活化、转移与应力的因果联系，为深入探讨韧性剪切带动力成岩作用提供理论的科学依据，为探讨中、下地壳中韧性剪切带的形成和演化提供科学依据，同时为韧性剪切变形作用条件下成岩、成矿地球化学作用提供理论和实验依据；⑤现代分析技术如激光同位素原位分析以及激光ICP-MASS分析技术对研究变形域内的岩石的元素和同位素的活化迁移规律，对深刻揭示糜棱岩化过程中的元素活化迁移机制提供更高质量的地球化学证据具有重要的作用。

In normal state,δ13C in biogenic alkane gas increases, while its component content decreases, with increase of the carbon numbers. In Section-1 gas pool of Leikoupo formation of Middle Triassic in Moxi gas field of central Sichuan, both of the component content and δ13C series appear reversals.

正常状态下，有机烷烃气的碳同位素值(δ13C)依碳数递增而递增，其组分含量依碳数递增而递减，而川中磨溪气田中三叠统雷口坡组一段气藏，有机烷烃气的组分含量和碳同位素系列却出现了倒转。

However, the helium isotope analysis data are quite different between them. The abnormal of helium isotope made sure of extraterrestrial origin of iron cosmic spherules.

宇宙球粒的氦同位素分析值却截然不同；3He/4He×10^(-8)分别为：57.50±2.16和1.23±0.43；4He×10^(-8)cm^3 STP/g分别为：55.54和809.6；然而宇宙球粒的氦同位测定值都比各自的母岩高出许多；氦同位素的异常为所发现的宇宙球粒的地外来源更加确定。

objective the aim of this study is to investigate the expression and the distribution of the nerve growth factor during the period of neural tube development of human embryo.method early development of neural tube was studied in human embryos about 35 gestational days by using immunocytochemical abc technique.result there were ngf immuno-positive substances in the cytoplasm and nuclei of neuroepithelial cells in the ventricular zones of neural tube.in the intermediate zone of neural tube,ngf immunoreactivity was detected in the nuclei of some neurons,or the processes of other neurons which contained no ngf-immunoreactive substances in their nuclei;the expression pattern of ngf in the marginal zone of neural tube was similar to that of the intermediate zone.the density of ngf-immunorecative particles was higher on the rostrum side of neural tube than on the caudal side.the ngf immuno-positive cells were also observed among the somites of embryo under the neural tube.conclusion these results suggest that ngf was an important signal molecule to induce neural tube differentiation,and that ngf may play a significant role in regulation of the biological function of neurons in developing neural tube.

目的 研究捷安肽素的抗真菌作用机理。方法采用形态学方法和同位素标记法。显微形态观察经捷安肽素处理后的供试真菌的形态学变化。进一步采用14c同位素标记的特异底物&尿苷二磷酸-（14c）-葡萄糖&示踪，研究捷安肽素对真菌(1，3)-β-d-葡聚糖合成酶活性反应的影响。结果研究神经生长因子在早期人胚神经管发育过程中的定位表达。方法采用免疫细胞化学 abc法染色，研究35天人胚的发育情况。结果在人胚神经管的室管带中，神经元的细胞质和细胞核ngf免疫反应阳性；在中间带，一部分神经元的细胞核ngf免疫反应阳性，另外一部分神经元的细胞核ngf免疫反应阴性，而其突起ngf免疫反应阳性；在边缘带ngf的表达与中间带相似。在神经管的头侧ngf阳性反应较强，神经管的尾侧ngf阳性反应较弱。结论 ngf在人胚神经管免疫反应阳性，表明ngf可能是诱导神经管分化发育的重要信号分子，提示ngf可能在人胚神经管的发育中具有十分重要的作用。神经生长因子；人胚；神经管；发育

A recent discovery makes such a determination possible: relative land-ice volume for a given period can be deduced from the ratio of two oxygen isotopes, 16 and 18, found in ocean sediments.

最近的一个发现使得这样的测定变得可行：过去某一时期相对陆地冰的数量可以从两种氧同位素，氧16和氧18的比例中推算出，这两种同位素发现于海洋沉积物中。

It was shown that the SNR of the RADS could be improved by using a microwave cavity with proper microwave field mode and high microwave filling factor, a rubidium spectrum lamp with high spectrum purity and a separated isotope filtering scheme in the physics package design. The performance of the rubidium atomic frequency standard could be improved by taking all these factors into consideration.

本文分析了微波腔的结构、铷光谱灯的光谱纯度和同位素滤光方案对信噪比的影响，指出采用模式优越、微波填充因子大的微波腔，光谱纯度高的铷光谱灯，用分离滤光方法进行同位素滤光，可以提高铷原子鉴频信号的信噪比，从而使铷频标的稳定度指标得到进一步改善。

Studies of Sr, Nd and Pb isotopes of various stratigraphic units, granite plutons and fluorite ores indicate that the metallogenic materials of fluorite were derived from multiple sources, and the isotopic composition of fluorite is characterized by crust_mantle mixed sources.

各地层单元、花岗岩体和萤石矿石的Sr、Nd、Pb同位素研究表明，萤石的放射性同位素组成具有壳、幔源混合的特点，成矿物质来源具有多源性。

Introduction of C 4 food had strong effect on stable isotope metabolism (especially for stable nitrogen isotope) of plateau pikas.

介绍了同位素分馏的基本概念以及利用稳定同位素研究水体蒸发的基本原理。

On the other hand, the more important thing is because the urban housing is a kind of heterogeneity products.

另一方面，更重要的是由于城市住房是一种异质性产品。

Climate histogram is the fall that collects place measure calm value, cent serves as cross axle for a few equal interval, the area that the frequency that the value appears according to place is accumulated and becomes will be determined inside each interval, discharge the graph that rise with post, also be called histogram.

气候直方图是将所收集的降水量测定值，分为几个相等的区间作为横轴，并将各区间内所测定值依所出现的次数累积而成的面积，用柱子排起来的图形，也叫做柱状图。