首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   130111篇
  免费   2324篇
  国内免费   1038篇
测绘学   3038篇
大气科学   8826篇
地球物理   25782篇
地质学   46531篇
海洋学   11825篇
天文学   29433篇
综合类   372篇
自然地理   7666篇
  2022年   789篇
  2021年   1389篇
  2020年   1538篇
  2019年   1666篇
  2018年   3522篇
  2017年   3297篇
  2016年   4016篇
  2015年   2194篇
  2014年   3890篇
  2013年   6922篇
  2012年   4164篇
  2011年   5543篇
  2010年   4881篇
  2009年   6287篇
  2008年   5664篇
  2007年   5627篇
  2006年   5193篇
  2005年   3954篇
  2004年   3838篇
  2003年   3614篇
  2002年   3445篇
  2001年   3117篇
  2000年   3015篇
  1999年   2429篇
  1998年   2547篇
  1997年   2351篇
  1996年   2021篇
  1995年   2019篇
  1994年   1723篇
  1993年   1610篇
  1992年   1528篇
  1991年   1483篇
  1990年   1558篇
  1989年   1348篇
  1988年   1227篇
  1987年   1478篇
  1986年   1273篇
  1985年   1567篇
  1984年   1755篇
  1983年   1682篇
  1982年   1576篇
  1981年   1418篇
  1980年   1305篇
  1979年   1238篇
  1978年   1201篇
  1977年   1050篇
  1976年   1033篇
  1975年   985篇
  1974年   989篇
  1973年   1030篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
291.
Indonesia is one of the most rapidly developing nations in the world. One important component of its transformation is an industrialisation policy which sees its people utilised by transnational corporations as sources of cheap labour for export goods processing. This has both positive and negative outcomes. This paper explores these issues in a review of Indonesian development strategy with particular reference to Batam Island in Riau Province.  相似文献   
292.
293.
294.
We review the present understanding of interstellar CH+. We show that the essential chemistry was correctly identified by Bates and Spitzer in 1951. More recent work has been concerned with defining appropriate venues within which this chemistry can function efficiently. This process had led to a much fuller understanding of the nature of the interstellar medium.  相似文献   
295.
296.
Robe's restricted three-body problem is reanalyzed with a view to incorporate a new assumption, namely that the configuration of the fluid body is that described by an hydrostatic equilibrium figure (Roche's ellipsoid). In the concomitant gravitational field a full treatment of the buoyancy force is given. The pertinent equations of motion are derived, the linear stability of the equilibrium solution is studied and the connection between the effect of the buoyancy forces and a perturbation of the Coriolis force is pointed out.  相似文献   
297.
The restricted problem of 2 + 2 bodies when one of the infinitesimal masses is further acted upon by the light pressure of the two primaries, is considered. The stationary solutions of this problem are found out. A short discussion is devoted to the stability of these solutions.  相似文献   
298.
Perspectives for the Radio-Optical Telescope 54/32/2.6 are given for scientific research in radioastronomy. Its characteristics and potential scientific fields are summarized in the frame of the present French-Armenian collaboration. A 3-phase upgrade plan including a detailed technical evaluation of the antenna is presented.Published in Astrofizika, Vol. 38, No. 4, pp. 645–648, October–December, 1995.  相似文献   
299.
We have studied the influence of the magnetic helicity on solar particle propagation using the IMF data observed by the HELIOS spacecraft in the range 0.31–0.95 AU, during eight solar proton events. For this, we have derived power and helicity spectra of the turbulence of the magnetic field during the time of the events. These are used to compute the particle pitch-angle scattering coefficients according to the quasi-linear theory (QLT) treatment of particle propagation in turbulent magnetic fields. The results show that in all the cases the helicity effects are negligible and the particle's mean free paths deduced from the pitch-angle diffusion coefficients are the same regardless of whether or not helicity effects are included in the calculations. The computed mean free paths are quite different in each case.Deceased 10 April, 1995.  相似文献   
300.
Wolf-Rayet stars     
Summary Recent literature on Population I Wolf-Rayet star research extending from the Milky Way to blue compact dwarf galaxies is reviewed, broken down into inventory, basic parameters and galactic distribution, atmospheres, binaries, intrinsic variability, mass loss, enrichment and evolution. Also the incidence of Wolf-Rayet stars with variable non-thermal radio emission, excess X-ray fluxes, and episodic/periodic IR excesses is reviewed. These phenomena appear to be associated with wind-wind interaction in wide long-period WR+OB binaries and with wind-compact object interaction in WR+c binaries, with orbit sizes of the order of magnitude of the WR radio photosphere sizes or larger.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号