全文获取类型
收费全文 | 1334篇 |
免费 | 282篇 |
国内免费 | 223篇 |
专业分类
测绘学 | 35篇 |
大气科学 | 78篇 |
地球物理 | 531篇 |
地质学 | 461篇 |
海洋学 | 68篇 |
天文学 | 573篇 |
综合类 | 41篇 |
自然地理 | 52篇 |
出版年
2024年 | 8篇 |
2023年 | 14篇 |
2022年 | 29篇 |
2021年 | 29篇 |
2020年 | 32篇 |
2019年 | 39篇 |
2018年 | 34篇 |
2017年 | 55篇 |
2016年 | 32篇 |
2015年 | 36篇 |
2014年 | 43篇 |
2013年 | 54篇 |
2012年 | 59篇 |
2011年 | 44篇 |
2010年 | 58篇 |
2009年 | 118篇 |
2008年 | 99篇 |
2007年 | 113篇 |
2006年 | 122篇 |
2005年 | 93篇 |
2004年 | 113篇 |
2003年 | 82篇 |
2002年 | 83篇 |
2001年 | 72篇 |
2000年 | 73篇 |
1999年 | 58篇 |
1998年 | 52篇 |
1997年 | 28篇 |
1996年 | 36篇 |
1995年 | 27篇 |
1994年 | 24篇 |
1993年 | 12篇 |
1992年 | 19篇 |
1991年 | 14篇 |
1990年 | 12篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1983年 | 1篇 |
排序方式: 共有1839条查询结果,搜索用时 0 毫秒
1.
K. A. van der Hucht 《Astronomy and Astrophysics Review》1992,4(2):123-159
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
2.
Benedetta Ciardi † rea Ferrara 《Monthly notices of the Royal Astronomical Society》2001,324(3):648-652
We calculate the expected mid-infrared (MIR) molecular hydrogen line emission from the first objects in the Universe. As a result of their low masses, the stellar feedback from massive stars is able to blow away their gas content and collect it into a cooling shell where H2 rapidly forms and IR roto-vibrational (as for example the rest-frame 2.12 μm) lines carry away a large fraction (up to 10 per cent) of the explosion energy. The fluxes from these sources are in the range 10−21 –10−17 erg s−1 cm−2 . The highest number counts are expected in the 20-μm band, where about 105 sources deg−2 are predicted at the limiting flux of 3×10−18 erg s−1 cm−2 . Among the planned observational facilities, we find that the best detection perspectives are offered by the Next Generation Space Telescope ( NGST ), which should be able to reveal about 200 first objects in one hour observation time at its limiting flux in the above band. Therefore, mid-IR instruments appear to represent perfect tools to trace star formation and stellar feedback in the high ( z ≳5) redshift Universe. 相似文献
3.
4.
5.
6.
7.
8.
9.
Historical space as narrative medium: on the configuration of spatial narratives of time at historical sites 总被引:1,自引:0,他引:1
This paper examines how narratives of history are organized spatially at historical sites and memorial spaces, especially
in urban settings and in places invested with a sense of collective memory. Much recent research has focused on landscape,
memory, and place and how relationships of political and social power influence the representation of historical events in
public spaces. Although the meaning of such sites may be hotly contested for long periods of time, we focus here on narrative
theory and the related, but unexplored, issue of how such historical stories are configured on the ground at actual historical
sites. We identify a number of narrative strategies which are frequently used to configure historical stories in space. Declamatory
strategies using markers presenting a snapshot of an event are common, but sequential and non-sequential linear strategies
are also used, as are thematic strategies that cross-cut space and time to present complex historical stories at various spatial
scales. Examples are drawn from a range of historical sites in North America, Europe and Israel. 相似文献
10.
Starting from the widespread phenomena of porous bottoms in the near shore region, considering fully the diversity of bottom topography and wave number variation, and including the effect of evanescent modes, a general linear wave theory for water waves propagating over uneven porous bottoms in the near shore region is established by use of Green‘s scond identity. This theory can be reduced to a number of the most typical mild-slope equations curreutly in use and provide a reliable research basis for follow-up development of nonlinear water wave theory involving porous bottoms. 相似文献