全文获取类型
| 收费全文 | 39173篇 |
| 免费 | 1414篇 |
| 国内免费 | 391篇 |
专业分类
| 测绘学 | 1006篇 |
| 大气科学 | 3047篇 |
| 地球物理 | 10320篇 |
| 地质学 | 13726篇 |
| 海洋学 | 2701篇 |
| 天文学 | 7603篇 |
| 综合类 | 276篇 |
| 自然地理 | 2299篇 |
出版年
| 2021年 | 333篇 |
| 2020年 | 362篇 |
| 2019年 | 353篇 |
| 2018年 | 1250篇 |
| 2017年 | 1146篇 |
| 2016年 | 1294篇 |
| 2015年 | 901篇 |
| 2014年 | 1118篇 |
| 2013年 | 1844篇 |
| 2012年 | 1688篇 |
| 2011年 | 1773篇 |
| 2010年 | 1361篇 |
| 2009年 | 1712篇 |
| 2008年 | 1447篇 |
| 2007年 | 1429篇 |
| 2006年 | 1337篇 |
| 2005年 | 1774篇 |
| 2004年 | 1834篇 |
| 2003年 | 1578篇 |
| 2002年 | 1064篇 |
| 2001年 | 900篇 |
| 2000年 | 789篇 |
| 1999年 | 678篇 |
| 1998年 | 703篇 |
| 1997年 | 687篇 |
| 1996年 | 525篇 |
| 1995年 | 516篇 |
| 1994年 | 496篇 |
| 1993年 | 412篇 |
| 1992年 | 388篇 |
| 1991年 | 367篇 |
| 1990年 | 405篇 |
| 1989年 | 375篇 |
| 1988年 | 295篇 |
| 1987年 | 394篇 |
| 1986年 | 325篇 |
| 1985年 | 438篇 |
| 1984年 | 450篇 |
| 1983年 | 443篇 |
| 1982年 | 415篇 |
| 1981年 | 378篇 |
| 1980年 | 385篇 |
| 1979年 | 351篇 |
| 1978年 | 398篇 |
| 1977年 | 328篇 |
| 1976年 | 330篇 |
| 1975年 | 347篇 |
| 1974年 | 290篇 |
| 1973年 | 316篇 |
| 1971年 | 219篇 |
排序方式： 共有10000条查询结果，搜索用时 31 毫秒
31.
In this paper we analyse error-removing techniques used without sufficient theoretical support in a previous paper, where Chandrasekhar's higher-order perturbation theories were developed for either uniformly or differentially-rotating polytropic stars. 相似文献
32.
33.
A new procedure to separate the instrumental and atmospheric components of stray light is presented. It is based on the dependence of the aureole's atmospheric component on the air mass and is applied to measurements taken with the Vacuum Newton Telescope (VNT) at the Observatorio del Teide (Tenerife). The resulting instrumental part is independent of the air mass.The variation of both components with wavelength is also studied. The instrumental component shows no dependence on wavelength, in contrast to the atmospheric one which is greater in the blue than in the red.It is concluded that observations with air masses larger than two will probably be strongly affected by stray light. 相似文献
34.
35.
An updated Lagrangian finite-element formulation has been developed for time-dependent problems of soil consolidation involving finite deformations. Large plastic strains as well as rotations occur in such problems and nominal stress measures are introduced in the formulation to redefine stresses. This leads to corrective terms for equilibrium and yield violations in addition to geometric stiffening terms in the governing integral equations. The soil is considered to be either a linear elastic or an elastoplastic, critical-state material. Some simple numerical examples are studied to validate the formulation, followed by a detailed analysis of the problem of penetration of a pile into soil. The results of this problem are viewed with emphasis on the physical interpretation and practical significance. 相似文献
36.
37.
38.
39.
We have derived the galaxy luminosity function in various regions of the cluster of galaxies Abell 496 from a wide field image
in the I band. A Schechter function fit in the 17≤ IAB ≤22(–19.5≤ MIAB ≤ –14.5) magnitude interval gives a steep power law index, which is somewhat steeper in the outer regions than in the inner
zones. This result agrees with previous findings obtained by several teams on the Coma cluster and can be interpreted as due
to the fact that faint galaxies are accreted by large ones in the central regions.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
40.