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991.
992.
Du Andao He Hongliao Yin Ningwan Zou Xiaoqiu Sun Yali Sun Dezhong Chen Shaozhen Qu Wenjun 《《地质学报》英文版》1995,8(2):171-181
Abstract This study deals with the first application of the isotope dilution-inductively coupled plasma mass spectrometry in the rhenium-osmium geochronometry in China. The chemical separation procedure included decomposition of samples by means of alkali fusion, extraction of rhenium by acetone and extraction of osmium by distillation. The recovery of both elements in the entire process was more than 90% . The blanks of analyses were 0.07 ng for rhenium and 0.01 ng for <sup>187</sup>Os. The mineralization ages of molybdenites from four molybdenum deposits in China were determined by using this method, with a precision (2σ) of about ±3% . These results agree satisfactorily with their geological backgrounds. The Re-Os method can directly determine ages of metal deposits and reflect the true ages more reliably than other dating methods that only determine the ages of country rocks from which mineralization ages are inferred. As many hydrothermal sulphide deposits usually contain molybdenites, this method has bright prospects of wide application. 相似文献
993.
994.
戈壁风沙流若干特征研究 总被引:15,自引:10,他引:15
本文从理论推导入手,阐述了戈壁风沙流中沙粒起跃角度、跃移高度和风沙流结构、强度、能量分布状况等特征,指出与流沙地表风沙流的显著差异,并得到风洞实验验证。 相似文献
995.
盐湖卤水的蒸发结晶过程 总被引:3,自引:4,他引:3
本文从实验和理论相结合的角度上,总结了三十多年我国数十个盐湖等温蒸发和天然蒸发研究结果和研究经验,概括了三种类型盐湖卤水蒸发结晶的规律性,推荐了卤水蒸发结晶的相化学基础数据.对氯化物型卤水,由于介稳程度小,可采用Zdanovskii推荐的四元体系Na+、K+、Mg(2+)∥Cl-—H2O平衡相图进行太阳池工艺计算;对于硫酸盐型卤水,宜用金作美五元体系Na+、K+、Mg(2+)∥Cl-、SO,-H2O介稳相图,而不是Van’tHoff平衡相图;对于后期,锂盐高度浓缩,宜用我们的四元体系Li+、Mg(2+)∥Cl-、SO-H2O介稳相因;对于碳酸盐型盐湖卤水,可用我们的五元体系Na+、K+∥Cl-、CO、SO-H2O介稳相图作为相化学基础,而不是Teeple平衡相图.从相平衡热力学角度上,实现了对卤水蒸发结晶过程的理论描述、计算和预测.其中对一里坪、达布逊、东台吉乃尔、西台吉乃尔等盐湖卤水的研究结果尚属首次报道. 相似文献
996.
用高分辨电子显微术和光学衍射技术研究了莱河矿的三种超结构类型——3C_1,2C,3C_2。超结构的存在是由于Fe~(2+)空位的不同有序分布产生的。通过观察象与模拟象的比较,建立了相应的结构模型。 相似文献
997.
By expressing the stream function in terms of the symmetric and the antisymmetric components with respect to the equator,the barotropic vorticity equation can be separated into two equations,one describing the behaviours of the atmospheric symmetric motion,and the other those of the atmospheric antisymmetric motion.From them,for the entire global surface at the equivalent barotropic level,the conservations of several basic quantities,such as vorticity,angular momentum etc.in the symmetric and antisymmetric cases,have been discussed.In addition,the energy budget equations and the energy conservation expressions for the two kinds of motion are given.It can be seen from them that there are not only the conversion between the zonal mean kinetic energy and the disturbed kinetic energy in the atmosphere,but also the conversion between the kinetic energy generated by the symmetric and antisymmetric motions.In the case of including orography and horizontal diffusion into the vorticity equation,a mechanism of the generation of asymmetric behaviours of the atmosphere is proposed.The results show that the asymmetric distribution of orography and that of horizontal diffusion coefficients are likely the causes leading to the asymmetric motion.Finally,a theoretical comparison between the global model and the hemispheric one from the physical point of view is made. 相似文献
998.
In consideration of the radiation transfer, latent and sensible heat exchange between oceans and at-mosphere, a three-dimensional autonomous nonlinear ordinary differential equation is established by statis-tical parameterization method. The variables of the model are the mean ocean surface temperature Ts, mean atmospheric temperature Ta and atmospheric relative humidity f, and the feedbacks of clouds, water vapor and CO2 are involved. The steady state corresponding to the present-day climate can be obtained from this model. The analysis of parameter sensibility in the steady state indicates that clouds have consid-erable negative feedback effects and water vapor may affect the sign of CO2 feedback. The stability analysis of the steady state to small disturbance indicates that with increase of the positive feedback effect of clouds, the steady state goes through such a structural variance series as a stable node→a stable focal point→an unstable focal point→an unstable node, and when the steady state becomes unstable it undergoes a subcritical Hopf bifurcation. When the steady state is at a focal point, the periodic oscillation solutions of damping or amplifying can be obtained with the period being about two years. 相似文献
999.
活动断裂的遥感影像研究 总被引:1,自引:0,他引:1
本文以遥感信息作为研究活动断裂的依据,探讨了利用不同种类、不同比例尺遥感图像分析活动断裂的方法、程序和效果。 相似文献
1000.
对1994年6月下旬山东省久旱转雨天气过程的预报及服务情况进行了总结。分析预报过程表明,充分了解和掌握西风带系统对西太平洋副热带高压变化的影响,抓住引起副高突然西进北上的环流特征,将经验预报指标、数值预报、客观预报方法三者结合起来,配合使用,是做好这次重大转折天气预报的关键。 相似文献