全文获取类型
收费全文 | 24440篇 |
免费 | 1414篇 |
国内免费 | 893篇 |
专业分类
测绘学 | 1204篇 |
大气科学 | 716篇 |
地球物理 | 2480篇 |
地质学 | 3400篇 |
海洋学 | 769篇 |
天文学 | 16656篇 |
综合类 | 547篇 |
自然地理 | 975篇 |
出版年
2024年 | 65篇 |
2023年 | 154篇 |
2022年 | 268篇 |
2021年 | 322篇 |
2020年 | 329篇 |
2019年 | 413篇 |
2018年 | 244篇 |
2017年 | 296篇 |
2016年 | 320篇 |
2015年 | 415篇 |
2014年 | 423篇 |
2013年 | 471篇 |
2012年 | 501篇 |
2011年 | 498篇 |
2010年 | 507篇 |
2009年 | 1810篇 |
2008年 | 1803篇 |
2007年 | 2053篇 |
2006年 | 2049篇 |
2005年 | 1847篇 |
2004年 | 1922篇 |
2003年 | 1660篇 |
2002年 | 1479篇 |
2001年 | 1261篇 |
2000年 | 1063篇 |
1999年 | 1023篇 |
1998年 | 1199篇 |
1997年 | 336篇 |
1996年 | 200篇 |
1995年 | 336篇 |
1994年 | 346篇 |
1993年 | 197篇 |
1992年 | 113篇 |
1991年 | 118篇 |
1990年 | 109篇 |
1989年 | 148篇 |
1988年 | 98篇 |
1987年 | 99篇 |
1986年 | 80篇 |
1985年 | 45篇 |
1984年 | 31篇 |
1983年 | 27篇 |
1982年 | 8篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1954年 | 4篇 |
1900年 | 3篇 |
1897年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
351.
352.
353.
354.
355.
356.
357.
358.
We investigate the metal enrichment of the intra-cluster medium by using a method that combines N-Body simulations and a semi-analytic
model (SAM) of galaxy formation. The cluster of galaxies is simulated in a flat, low density universe, with a numerical resolution
that allows the detection of substructures in the dark matter background of the cluster. The phenomenological approach used
to model the physical processes involved in the galaxy formation and metal production is applied to the substructures found
in the dark matter halos detected at different redshifts. Details of the chemical implementation in the SAM and first results
related to the mean properties of the baryonic matter components are presented.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
359.
360.
Dark energy has a dramatic effect on the dynamics of the Universe, causing the recently discovered acceleration of the expansion. The dynamics are also central to the behaviour of the growth of large-scale structure, offering the possibility that observations of structure formation provide a sensitive probe of the cosmology and dark energy characteristics. In particular, dark energy with a time-varying equation of state can have an influence on structure formation stretching back well into the matter-dominated epoch. We analyse this impact, first calculating the linear perturbation results, including those for weak gravitational lensing. These dynamical models possess definite observable differences from constant equation of state models. Then we present a large-scale numerical simulation of structure formation, including the largest volume to date involving a time-varying equation of state. We find the halo mass function is well described by the Jenkins et al. mass function formula. We also show how to interpret modifications of the Friedmann equation in terms of a time-variable equation of state. The results presented here provide steps toward realistic computation of the effect of dark energy in cosmological probes involving large-scale structure, such as cluster counts, the Sunyaev–Zel'dovich effect or weak gravitational lensing. 相似文献