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991.
An important contribution to the thermalization of the solar wind ions at the Earth's bow shock for high Mach numbers comes from the reflection of a fraction of these ions from the shock. Previous studies have examined the trajectories of the reflected ions assuming the shock to be an infinite plane. In this paper a model is developed to describe the trajectories of particles after reflection for a variety of shock geometries. Of particular interest are the initial conditions which allow the particle to return to the shock with a greater normal velocity than at first encounter, or to return to the shock at all. The effects of the magnetic field direction and the curvature of the shock on particle trajectories are discussed for cylindrical and spherical shock geometries and compared to those for a planar shock. 相似文献
992.
热休克蛋白22(HSP22)是唯一在体外能以单体形式存在的小分子热休克蛋白(sHSP),具有分子伴侣功能和激酶活性。HSP22高水平表达促进细胞凋亡而低水平表达抑制凋亡。除此之外,HSP22还在延长寿命、耐热和抗氧化等方面发挥作用。由于其独特的生物学功能,HSP22正成为当今研究热门对象之一。近年来,HSP22在医学方面的研究已取得显著进展,其在海洋生物学方面的研究价值也逐渐得到重视。本文综述了近年来HSP22结构和功能及其在医学和海洋生物学上的研究进展。 相似文献
993.
PHYSICAL STRUCTURE OF GEOGRAPHICAL ENVIRONMENT-INTEGRITY AND DISPARITY,GENERALITY AND INDIVIDUALITY 总被引:1,自引:0,他引:1
李春芬 《中国地理科学(英文版)》1993,(4)
Integrity and disparity are two of the basic characteristics implied in the scientific connotation of the physical environment as a material system. From a dialectical materialistic point of view the physical character of geographical environment of the earth surface is the unity in diversity. It is on such grounds that the two basic characteristics were put forth by the author in his monograph "Physical Structure of South American Geographical Environment" as the underlying theme. This holds true for the hierarchy of physical regions. For instance, the physical environment of the earth surface in unity behaves as a huge whole, yet, in differentiation into continents, it displays disparity; each continent differs from others and becomes an integrity in its own right. The same is true of regions of lower levels. In the case of generality and individuality of regional types and their constituent distributive areas in different continents, the same relationship exists among them. Owing to similar origin ea 相似文献
994.
Numerical Analysis on the Effects of Submerged Depth of the Grid and Direction of Incident Wave on Gravity Cage 总被引:1,自引:0,他引:1
In this paper,the numerical model of the net cage with the grid mooring system in waves is set up by the lumped mass method and rigid kinematics theory,and then the motion equations of floating system,net system,mooring system,and floaters are solved by the Runge-Kutta fifth-order method.For the verification of the numerical model,a series of physical model tests have been carried out.According to the comparisons between the simulated and experimental results,it can be found that the simulated and experimental results agree well in each condition.Then,the effects of submerged depth of grid and direction of incident wave propagation on hydrodynamic behaviors of the net cage are analyzed.According to the simulated results,it can be found that with the increase of submerged depth of grid,the forces acting on mooring lines and bridle lines increase,while the forces on grid lines decrease;the horizontal motion amplitudes of floating collar decrease obviously,while the vertical motion amplitudes of floating collar change little.When the direction of incident wave propagation changes,forces on mooting lines and motion of net cage also change accordingly.When the propagation direction of incident wave changes from 0° to 45°,forces on the main ropes and bridle ropes increase,while the forces on the grid ropes decrease.With the increasing propagation direction of incident wave,the horizontal amplitude of the forces collar decreases,while the vertical amplitude of the floating collar has little variation. 相似文献
995.
996.
探讨了区域物性参数统计整理方法,把概率论运用于物性参数统计中,提出参数幅度特征的概念。论述了多元物性参数的组合分析方法。为综合物理场的判断解释及项目设计阶段物探方法的有效选择提供了一种较有效的分析思路。 相似文献
997.
自然资源管理的核心问题是产权制度的落实,在一套具有法律地位的成果底图上,将资源属性向价值属性拓展,即自然资源资产化过程,为解决现实中山、水、林、田、湖、草等自然资源产权制度因服务多个部门行政管理需要而导致的产权分散独立的问题提供了解决方法.本文以森林资源为例,设计第三次国土调查工作分类与自然资源分类的对应方法,通过计算... 相似文献
998.
GPS时间序列与强震预测研究 总被引:3,自引:1,他引:3
应用经验正交函数(EOF)分析方法,对中国大陆连续观测的基准站水平位移时间序列进行分析。通过对1999年3月份以来GPS1000周至1258周的原始时间序列的EOF分析、时间序列中除去长期位移速率后的EOF分析、及强震前半年时间段内的时间序列的EOF分析,研究强震前中国大陆水平位移场的时空演化特征及与强震发生的关系。 相似文献
999.
李春芬 《中国地理科学(英文版)》1992,(3)
There are a number of factors involved in teaching quality. Among them teaching materials or textbooks are of primary importance, the presentation of which relies first of all on the viewpoint to structure the contents geographically. Whatever branch of geography you are teaching or in pursuit, geographical viewpoint is vitally important. This paper in discussing innovation of geographical education about these institutions with the course of regional physical geography as an example. The higher education of our discipline is in pressing need of innovation and thereby upgrading quality. 相似文献
1000.
以少震弱震的江西萍乡地区为例,通过问卷调查的方式分析了该区民众防震减灾意识的现状及特点,讨论了相应的防震减灾宣教意义。主要结论如下:1)当地民众对本地灾害的认知情况与灾害的实际发生频率基本一致;对地震等本地少发灾害影响的认可性不高。2)民众的防震减灾意识薄弱,对地震灾害基本概念了解不足,地震谣言辨识能力差,基本防震减灾技能掌握不全面。3)获取防震减灾知识与技能主要通过新闻媒体和学校。4)民众学习防震减灾知识与技能的意愿强烈。因而,有针对性地开展防震减灾教育和宣传工作,加强地震应急演练,对于提高当地民众的防震减灾技能和灾害意识,减少地震灾害损失具有重要的现实意义。 相似文献