全文获取类型
收费全文 | 89364篇 |
免费 | 1278篇 |
国内免费 | 574篇 |
专业分类
测绘学 | 1859篇 |
大气科学 | 5943篇 |
地球物理 | 17141篇 |
地质学 | 32235篇 |
海洋学 | 8145篇 |
天文学 | 20563篇 |
综合类 | 238篇 |
自然地理 | 5092篇 |
出版年
2022年 | 643篇 |
2021年 | 1097篇 |
2020年 | 1174篇 |
2019年 | 1324篇 |
2018年 | 2659篇 |
2017年 | 2483篇 |
2016年 | 2850篇 |
2015年 | 1457篇 |
2014年 | 2770篇 |
2013年 | 4703篇 |
2012年 | 3028篇 |
2011年 | 3897篇 |
2010年 | 3536篇 |
2009年 | 4464篇 |
2008年 | 3885篇 |
2007年 | 3979篇 |
2006年 | 3687篇 |
2005年 | 2656篇 |
2004年 | 2597篇 |
2003年 | 2413篇 |
2002年 | 2394篇 |
2001年 | 2031篇 |
2000年 | 2012篇 |
1999年 | 1590篇 |
1998年 | 1666篇 |
1997年 | 1518篇 |
1996年 | 1297篇 |
1995年 | 1290篇 |
1994年 | 1089篇 |
1993年 | 1053篇 |
1992年 | 972篇 |
1991年 | 998篇 |
1990年 | 970篇 |
1989年 | 847篇 |
1988年 | 789篇 |
1987年 | 923篇 |
1986年 | 811篇 |
1985年 | 989篇 |
1984年 | 1115篇 |
1983年 | 1072篇 |
1982年 | 992篇 |
1981年 | 924篇 |
1980年 | 835篇 |
1979年 | 786篇 |
1978年 | 761篇 |
1977年 | 652篇 |
1976年 | 653篇 |
1975年 | 641篇 |
1974年 | 618篇 |
1973年 | 681篇 |
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
971.
972.
973.
Energy transport in a hot flare plasma is examined with particular reference to the influence of fluid motion. On the basis of dimensional considerations the dynamical timescale of the flare plasma is shown to be comparable to the timescale for energy loss by conduction and radiation. It is argued that mass motion is likely to have a profound influence on the evolution of the flare.The detailed response of a flare filament to a localized injection of energy is then analyzed. Radiative, conductive and all dynamical terms are included in the energy equation. Apart from greatly enhancing the rate of propagation of the thermal disturbance through space, mass motion is found to be significant in transferring energy through the moving fluid.Finally the predicted thermal structure is discussed and it is concluded that the presence of mass motions in the flare may be inferred from the form of the soft X-ray differential emission measure. 相似文献
974.
A. K. Singh 《Astrophysics and Space Science》1984,103(1):155-163
The three-dimensional flow of an electrically conducting and incompressible viscous fluid past a uniformly accelerated infinite vertical porous plate is studied in a rotating fluid. The flow is assumed to be at small magnetic Reynolds number so that the induced magnetic field is neglected. An exact solution has been obtained by defining a complex velocity with the help of the Laplace transform method for the Prandtl number equal to unity. The effects of rotation, magnetic and free-convection parameters are discussed for the whole problem. Also, the skin-friction components on the plate are discussed. 相似文献
975.
Mohamed Adel Sharaf Mervat El-Sayed Awad Mona A. Banaja 《Astrophysics and Space Science》1987,133(2):339-353
In this paper, economical and stable recurrence formulae for the Earth's zonal potential and its gradient for the KS regularized theory will be established for any numberN of the zonal harmonic coefficient. A general recursive computational algorithm based on these formulae is also established for the initial value problem of the KS theory for the prediction of artificial satellites in the Earth's gravitational field with axial symmetry. Applications of the algorithm for the problem of the final state prediction are illustrated by numerical examples of three test orbits each for two geopotential models corresponding toN=2 andN=36. A final state of any desired accuracy is obtained for each case study, a result which shows the flexibility of the algorithm. 相似文献
976.
977.
In this paper we offer a model for the Earth's ionosphere and plasmasphere, allowing for the inertia and anisotropic energy distribution of thermal plasma. A procedure for simultaneous solution of equations of continuity and motion for the O+ and H+ ions, subject to inertia terms, is described. The model also includes transfer equations for longitudinal and transversal thermal energies. The system of simulating equations and the kinetic equation for superthermal electron spectra are concordantly solved along geomagnetic field lines. Within the framework of the model we developed a study is made of the dynamics of filling of the evacuated plasmaspheric reservoir after a magnetospheric disturbance. It is shown that the filling of the tubes offorce with L ? 3.5 proceeds with supersonic speeds during the first several days and the character of filling differs very much from a diffusion-equilibrium one. The spatio-temporal behavior of electron and ion temperature anisotropy that is formed in the process of filling, is considered. It is found that the value of electron anisotropy can be large. A brief analysis is made of the causes of electron and ion temperature anisotropy. 相似文献
978.
979.
K. A. Shukurov I. I. Mokhov L. M. Shukurova 《Izvestiya Atmospheric and Oceanic Physics》2014,50(3):256-265
Temperature and radiation effects of the 2010 summer fires are estimated on the basis of measurements at the Zvenigorod Scientific Station (ZSS) of the Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (RAS), in the Moscow region. The surface air temperature during the 2010 summer smoke varied in antiphase with the aerosol mass concentration, and the thermal radiation balance in the surface layer of the atmosphere varied in phase. Under extreme smoke of the surface layer in August 2010, the reduction in surface air temperature at ZSS has been found to reach 4 K with an increase in the downward flux of thermal radiation by an average of 20 W/m2 and a decrease in the difference between upward and downward fluxes of thermal radiation by an average of 24 W/m2. 相似文献
980.
In this work, the history of the development of the Turali area (the Dagestan coast of the Caspian Sea) in the Late Holocene
is under consideration. The analysis of the geological structure of the bay bar that separates the Bolshoy Turali lagoon from
the sea, the granulometric analysis of the coastal deposits, and the data of geo-radar profiles make it possible to assert
that the large eolian relief forms were formed during the New Caspian (Novokaspiyskoe) transgression of the Caspian Sea. 相似文献