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天文因子与中国大地震活动趋势预测 总被引：1，自引：1，他引：0
根据太阳活动与月亮运动周期预测１９９８年开始的中国大地震活跃期已经基本结束,从现在起到２０００年中国大陆发生Ｍｓ≥７．０地震的可能性很小。 相似文献
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伽利略在1609年制造出天文望远镜后不久,消息就传到了中国。1618年,传教士汤若望和李祖白率先翻译了《远镜说》一书,介绍了望远镜的使用、原理、构造和制作方法。根据中德科技交流中心的说法,望远镜是在1619年由德国人邓玉函首次带入中国的。另外也可见到一种说法是,1622年汤若望首次把望远镜携入了中国。 相似文献
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2008年,对于13．2亿中国人民来说,是具有里程碑意义的一年!因为在这一年,中国将纪念拨开迷雾,摆脱无休止“文革”恶斗,终于踏上“改革开放”大道,阔步前进的30周年。 相似文献
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中国大陆地壳运动的背景场 总被引：1，自引：1，他引：0
利用中国大陆和周围地区的12个IGS站近3年（1995年5月-1998年3月）的GPS观测资料,确定了这些IGS站的水平位移速率,并用其研究中国大陆地壳构造运动的背景,得到了具有重要意义的推论。 相似文献
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利玛窦（意大利文：Matteo Ricci,1552年10月6日-1610年5月11日）,是耶稣会意大利传教士,1582年（明万历十年）来到澳门,次年利玛窦获准与罗明坚神父入居广东肇庆,1601年（明万历二十九年）抵达北京,1610年（明万历三十八年）去世。他在中国传教、生活了二十八年,将许多西方的天文学、地理学和数学知识传译到中国。 相似文献
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利用GPS技术监测中国大陆地壳运动的初步结果 总被引：8，自引：2，他引：6
国家攀登项目“现代地壳运动和地球动力学研究”八．五期间中国大陆布设了中国地壳运动ＧＰＳ监测网，并于１９９４年和１９９６年组织了两期全国性的联测，利用这两期复测资料在国内首次测定了分布于全国的２２个基准站的水平位移速率，这些结果可用来研究中国大陆地壳构造运动的运动学模型。 相似文献
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对低纬子午环的仪器误差作了分类，包括制造误差、安装误差、仪器重力变形和热变形的影响，还分别列出了各种误差测量设备的制造误差、安装误差、读数零点偏差及其漂移的影响。文中强调了在该仪器误差修正中，不建立和使用任何误差模型，而是采用实时测定值，并且特别注意消除系统误差的影响，在这基础上，才能通过重复采数来压缩随机误差的影响。 相似文献
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The main topic of long-term researches by G.A. Shajn is the nature of diffuse matter, its distribution in the Galaxy and extragalactic systems, interaction with the interstellar medium and hot stars,and the formation of emission and reflection nebulae and stars. Based on the analysis of experimental data, mainly photographic observations of nebulae in the Milky Way and extragalactic systems, he made conclusions and suggested well-founded hypotheses on a wide range of considered problems, including those related to cosmogony. The structure of nebulae, and their masses and sizes give reasons behind the conclusion that most of them are formed not in the process of ejection of matter from the stars, but rather they are objects which are born and evolve, and quite often are comprised of giant conglomerates of gas, dust and stars. The distribution of OB-type stars and nebulae in spiral branches points to their genetic relation and the fundamental role of the interstellar medium as the source of their formation. The structural features of nebulae are determined by the action of magnetohydrodynamic forces. Magnetic fields in a galaxy control the motion of diffuse gas-dust matter and ensure the maintenance of its spiral structure. These ideas continue being developed in modern directions of astrophysics. 相似文献
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时间频率量的特征及其对时频系统建设的影响 总被引：2，自引：1，他引：1
分析了物理量测量中时间频率量的特点，主要有：时间的流逝性；其基准是自然基准；时间和频率既密切相关又有区别；时间频率具有最高的测量精细度(分辨率)与准确度；其计量标准可通过电磁波发播；其测量精确度与测量时间有关。另外，从基准、守时、授时、时间频率设备的研制、生产和队伍建设等方面阐发了这些特点对时间频率系统建设的影响。 相似文献
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V. N. Zharkov 《Earth, Moon, and Planets》1983,29(2):139-175
A survey is made of the physics of the interiors of Venus. The introduction explains the main concepts used in the construction of models of Venus and the history of the question; observational data are gathered and analyzed. The method of constructing the models of the planet is explained and earth-like models of Venus and parametrically simple PVM models are discussed. Within the compass of a physical nodel of Venus, the thermodynamics of the mantle and core is constructed and questions are discussed concerning the heat conduction, temperature distribution in the lithosphere and the thermal flux from the interior of Venus, the electrical conduction and mechanical quality, and large-scale steady stresses in the mantle of Venus. A rheological model of the crust and mantle is constructed. In conclusion, the question as to the distribution of radioactivity and convection in the interior of the planet is discussed. 相似文献
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Modern models of the formation of the regular satellites of giant planets, constructed with consideration for their structure and composition suggest that this process lasted for a considerable period of time (0.1–1 Myr) and developed in gas-dust circumplanetary disks at the final stage of giant planet formation. The parameters of protosatellite disks (e.g., the radial distribution of surface density and temperature) serve as important initial conditions for such models. Therefore, the development of protosatellite disk models that take into account currently known cosmochemical and physical restrictions remains a pressing problem. It is this problem that is solved in the paper. New models of the accretion disks of Jupiter and Saturn were constructed with consideration for the disk heating by viscous dissipation of turbulent motions, by accretion of material from the surrounding region of the solar nebula, and by radiation from the central planets. The influence of a set of input model parameters (the total rate of mass infall onto the disk, the turbulent viscosity and opacity of disk material, and the centrifugal radius of the disk) on thermal conditions in the accretion disks was studied. The dependence of opacity on temperature and the abundance and size of solid particles present in the disk was taken into account. Those constructed models that satisfy the existing constraints limit the probable values of input parameters (primarily rates of mass infall onto the disks of Jupiter and Saturn at the stage of regular satellite formation and, to a lesser extent, the disk opacities). Constraints on the location of the regions of formation of the major satellites of Jupiter and Saturn are suggested based on the constructed models and simple analytical estimates concerning the formation of satellites in the accretion disks. It is shown that Callisto and Titan could hardly be formed at significantly greater distances from their planets. 相似文献
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We analyze and compare the geomagnetic and galactic cosmic-ray (GCR) response of selected solar events, particularly the campaign events of the group International Study of Earth-affecting Solar Transients (ISEST) of the program Variability of the Sun and Its Terrestrial Impact (VarSITI). These selected events correspond to Solar Cycle 24, and we identified various of their features during their near-Earth passage. We evaluated the hourly data of geomagnetic indices and ground-based neutron monitors and the concurrent data of interplanetary plasma and field parameters. We recognized distinct features of these events and solar wind parameters when the geomagnetic disturbance was at its peak and when the cosmic-ray intensity was most affected. We also discuss the similarities and differences in the geoeffectiveness and GCR response of the solar and interplanetary structures in the light of plasma and field variations and physical mechanism(s), which play a crucial role in influencing the geomagnetic activity and GCR intensity. 相似文献
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The climatic impact of volcanic activity on the Earth and Mars is considered and a comparative analysis is made. The effect of gaseous components and of aerosols, formed in the process of the evolution of volcanic cloud, on the greenhouse effect and climate on the Earth and Mars is analyzed. A numerical modelling has shown that the climatic impact of volcanic activity depends on the optical properties (the extent of opacity of the atmospheric gaseous components and on the intensity of volcanic activity). In connection with sporadic variations in the intensity of volcanic activity, a temporal modulation of climate takes place with alternating periods of warming and cooling. An important role of SO2 and volcanic aerosols in the formation of climate in the presence of evolution of the Earth and Mars is revealed. 相似文献
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V. I. Ferronsky S. A. Denisik S. V. Ferronsky 《Celestial Mechanics and Dynamical Astronomy》1996,64(3):167-183
The physical meaning of the terms of the potential and kinetic energy expressions, expanded by means of the density variation function for a nonuniform self-gravitating sphere, is discussed. The terms of the expansions represent the energy and the moment of inertia of the uniform sphere, the energy and the moment of inertia of the nonuniformities interacting with the uniform sphere, and the energy of the nonuniformities interacting with each other. It follows from the physical meaning of the above components of the energy structure, and also from the observational fact of the expansion of the Universe that the phase transition, notably, fusion of particles and nuclei and condensation of liquid and solid phases of the expanded matter accompanied by release of energy, must be the physical cause of initial thermal and gravitational instability of the matter. The released kinetic energy being constrained by the general motion of the expansion, develops regional and local turbulent (cyclonic) motion of the matter, which should be the second physical effect responsible for the creation of celestial bodies and their rotation. 相似文献
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In June 2006 Venus Express crossed several times the outer boundary of Venus induced magnetosphere, its magnetosheath and its bow shock. During the same interval the Cluster spacecraft surveyed the dawn flank of the terrestrial magnetosphere, intersected the Earth's magnetopause and spent long time intervals in the magnetosheath. This configuration offers the opportunity to perform a joint investigation of the interface between Venus and Earth's outer plasma layers and the shocked solar wind. We discuss the kinetic structure of the magnetopause of both planets, its global characteristics and the effects on the interaction between the planetary plasma and the solar wind. A Vlasov equilibrium model is constructed for both planetary magnetopauses and provides good estimates of the magnetic field profile across the interface. The model is also in agreement with plasma data and evidence the role of planetary and solar wind ions on the spatial scale of the equilibrium magnetopause of the two planets. The main characteristics of the two magnetopauses are discussed and compared. 相似文献
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The surface area of Venus (∼460×106 km2) is ∼90% of that of the Earth. Using Magellan radar image and altimetry data, supplemented by Venera-15/16 radar images, we compiled a global geologic map of Venus at a scale of 1:10 M. We outline the history of geological mapping of the Earth and planets to illustrate the importance of utilizing the dual stratigraphic classification approach to geological mapping. Using this established approach, we identify 13 distinctive units on the surface of Venus and a series of structures and related features. We present the history and evolution of the definition and characterization of these units, explore and assess alternate methods and approaches that have been suggested, and trace the sequence of mapping from small areas to regional and global scales. We outline the specific defining nature and characteristics of these units, map their distribution, and assess their stratigraphic relationships. On the basis of these data, we then compare local and regional stratigraphic columns and compile a global stratigraphic column, defining rock-stratigraphic units, time-stratigraphic units, and geological time units. We use superposed craters, stratigraphic relationships and impact crater parabola degradation to assess the geologic time represented by the global stratigraphic column. Using the characteristics of these units, we interpret the geological processes that were responsible for their formation. On the basis of unit superposition and stratigraphic relationships, we interpret the sequence of events and processes recorded in the global stratigraphic column. The earliest part of the history of Venus (Pre-Fortunian) predates the observed surface geological features and units, although remnants may exist in the form of deformed rocks and minerals. We find that the observable geological history of Venus can be subdivided into three distinctive phases. The earlier phase (Fortunian Period, its lower stratigraphic boundary cannot be determined with the available data sets) involved intense deformation and building of regions of thicker crust (tessera). This was followed by the Guineverian Period. Distributed deformed plains, mountain belts, and regional interconnected groove belts characterize the first part and the vast majority of coronae began to form during this time. The second part of the Guineverian Period involved global emplacement of vast and mildly deformed plains of volcanic origin. A period of global wrinkle ridge formation largely followed the emplacement of these plains. The third phase (Atlian Period) involved the formation of prominent rift zones and fields of lava flows unmodified by wrinkle ridges that are often associated with large shield volcanoes and, in places, with earlier-formed coronae. Atlian volcanism may continue to the present. About 70% of the exposed surface of Venus was resurfaced during the Guineverian Period and only about 16% during the Atlian Period. Estimates of model absolute ages suggest that the Atlian Period was about twice as long as the Guineverian and, thus, characterized by significantly reduced rates of volcanism and tectonism. The three major phases of activity documented in the global stratigraphy and geological map, and their interpreted temporal relations, provide a basis for assessing the geodynamical processes operating earlier in Venus history that led to the preserved record. 相似文献