全文获取类型
| 收费全文 | 3462篇 |
| 免费 | 710篇 |
| 国内免费 | 176篇 |
专业分类
| 测绘学 | 47篇 |
| 大气科学 | 113篇 |
| 地球物理 | 550篇 |
| 地质学 | 1075篇 |
| 海洋学 | 809篇 |
| 天文学 | 1452篇 |
| 综合类 | 90篇 |
| 自然地理 | 212篇 |
出版年
| 2025年 | 13篇 |
| 2024年 | 84篇 |
| 2023年 | 85篇 |
| 2022年 | 76篇 |
| 2021年 | 102篇 |
| 2020年 | 78篇 |
| 2019年 | 106篇 |
| 2018年 | 74篇 |
| 2017年 | 85篇 |
| 2016年 | 84篇 |
| 2015年 | 100篇 |
| 2014年 | 109篇 |
| 2013年 | 108篇 |
| 2012年 | 101篇 |
| 2011年 | 145篇 |
| 2010年 | 121篇 |
| 2009年 | 279篇 |
| 2008年 | 256篇 |
| 2007年 | 269篇 |
| 2006年 | 269篇 |
| 2005年 | 212篇 |
| 2004年 | 222篇 |
| 2003年 | 186篇 |
| 2002年 | 172篇 |
| 2001年 | 163篇 |
| 2000年 | 155篇 |
| 1999年 | 146篇 |
| 1998年 | 145篇 |
| 1997年 | 51篇 |
| 1996年 | 48篇 |
| 1995年 | 44篇 |
| 1994年 | 45篇 |
| 1993年 | 21篇 |
| 1992年 | 18篇 |
| 1991年 | 20篇 |
| 1990年 | 24篇 |
| 1989年 | 30篇 |
| 1988年 | 9篇 |
| 1987年 | 14篇 |
| 1986年 | 11篇 |
| 1985年 | 22篇 |
| 1984年 | 18篇 |
| 1983年 | 8篇 |
| 1982年 | 6篇 |
| 1981年 | 10篇 |
| 1978年 | 3篇 |
| 1977年 | 1篇 |
排序方式： 共有4348条查询结果，搜索用时 230 毫秒
991.
J. E. Bowey A. J. Adamson J. A. Yates 《Monthly notices of the Royal Astronomical Society》2003,340(4):1173-1189
992.
993.
994.
995.
Bhuvnesh Jain Ryan Scranton Ravi K. Sheth 《Monthly notices of the Royal Astronomical Society》2003,345(1):62-70
Several measurements of quasi-stellar object (QSO)–galaxy correlations have reported signals much larger than predictions of magnification by large-scale structure. We find that the expected signal depends strongly on the properties of the foreground galaxy population. On arcmin scales, it can be either larger or smaller by a factor of 2 for different galaxy types in comparison with a linearly biased version of the mass distribution. Thus the resolution of some of the excess measurements may lie in examining the halo occupation properties of the galaxy population sampled by a given survey; this is also the primary information such measurements will provide.
We use the halo model of clustering and simulations to predict the magnification-induced cross-correlations and errors for forthcoming surveys. With the full Sloan Digital Sky Survey, the statistical errors will be below 1 per cent for the galaxy–galaxy correlations and significantly larger for QSO–galaxy correlations. Thus accurate constraints on parameters of the galaxy halo occupation distribution can be obtained from small-scale measurements and on the bias parameter from large scales. Since the lensing-induced cross-correlation measures the first moment of the halo occupation number of galaxies, these measurements can provide the basis for interpreting galaxy clustering measurements that measure the second- and higher-order moments. 相似文献
We use the halo model of clustering and simulations to predict the magnification-induced cross-correlations and errors for forthcoming surveys. With the full Sloan Digital Sky Survey, the statistical errors will be below 1 per cent for the galaxy–galaxy correlations and significantly larger for QSO–galaxy correlations. Thus accurate constraints on parameters of the galaxy halo occupation distribution can be obtained from small-scale measurements and on the bias parameter from large scales. Since the lensing-induced cross-correlation measures the first moment of the halo occupation number of galaxies, these measurements can provide the basis for interpreting galaxy clustering measurements that measure the second- and higher-order moments. 相似文献
996.
997.
The infrared emission of the H II region-molecular cloud complexes S 140, S 141 and S 142 is examined using the IRAS Sky Survey Atlases. The IRAF and Skyview software are used to draw the contour maps of infrared intensity, color temperature and optical depth of each source. The total infrared luminosity and dust distribution in the complexes are given. Compact clumps where star formation probably takes place are identified. The exciter star of S 141 is analyzed. 相似文献
998.
999.
N. D. R. Bhat F. Camilo J. M. Cordes D. J. Nice D. R. Lorimer S. Chatterjee 《Journal of Astrophysics and Astronomy》2002,23(1-2):53-57
The on-going Parkes multibeam survey has been astoundingly successful (Manchesteret al. 2001), and its discovery of over 600 pulsars has opened up new avenues for probing the Galaxy’s electron content and magnetic field. Here we report on recent observations made with the Arecibo 305-m telescope, where 80 distant, high dispersion measure pulsars (of which 35 are from the multibeam survey) were studied at multiple frequency bands in the range 0.4–2.4 GHz, in order to determine their scattering properties, rotation measures and spectral indices. The results will be used to meet a variety of science goals; viz., creating an improved model of the electron density, mapping out the Galactic magnetic field, and modeling the pulsar population. 相似文献
1000.
T. M. Gledhill A. Chrysostomou J. H. Hough J. A. Yates 《Monthly notices of the Royal Astronomical Society》2001,322(2):321-342
We use ground-based imaging polarimetry to detect and image the dusty circumstellar envelopes of a sample of protoplanetary nebulae (PPNe) at near-infrared wavelengths. This technique allows the scattered light from the faint envelope to be separated from the glare of the bright central star, and is particularly well suited to this class of object. We detect extended (up to 9-arcsec diameter) circumstellar envelopes around 15 out of 16 sources with a range of morphologies including bipolars and shells. The distribution of scattered light in combination with its polarization (up to 40 per cent) provides unambiguous evidence for axisymmetry in 14 objects, showing this to be a common trait of PPNe. We suggest that the range of observed envelope morphologies results from the development of an axisymmetric dust distribution during the superwind phase at the end of the AGB. We identify shells seen in polarized light with scattering from these superwind dust distributions, which allows us to provide constraints on the duration of the superwind phase. In one object (IRAS 19475+3119) the circumstellar envelope has a two-armed spiral structure, which we suggest results from the interaction of the mass-losing star with a binary companion. 相似文献