全文获取类型
收费全文 | 2957篇 |
免费 | 117篇 |
国内免费 | 32篇 |
专业分类
测绘学 | 68篇 |
大气科学 | 227篇 |
地球物理 | 730篇 |
地质学 | 985篇 |
海洋学 | 268篇 |
天文学 | 442篇 |
综合类 | 14篇 |
自然地理 | 372篇 |
出版年
2024年 | 5篇 |
2023年 | 6篇 |
2022年 | 8篇 |
2021年 | 54篇 |
2020年 | 47篇 |
2019年 | 55篇 |
2018年 | 64篇 |
2017年 | 66篇 |
2016年 | 89篇 |
2015年 | 89篇 |
2014年 | 91篇 |
2013年 | 179篇 |
2012年 | 139篇 |
2011年 | 186篇 |
2010年 | 141篇 |
2009年 | 167篇 |
2008年 | 154篇 |
2007年 | 161篇 |
2006年 | 142篇 |
2005年 | 125篇 |
2004年 | 124篇 |
2003年 | 109篇 |
2002年 | 100篇 |
2001年 | 71篇 |
2000年 | 64篇 |
1999年 | 59篇 |
1998年 | 53篇 |
1997年 | 37篇 |
1996年 | 44篇 |
1995年 | 30篇 |
1994年 | 34篇 |
1993年 | 32篇 |
1992年 | 29篇 |
1991年 | 26篇 |
1990年 | 24篇 |
1989年 | 23篇 |
1988年 | 25篇 |
1987年 | 29篇 |
1986年 | 24篇 |
1985年 | 32篇 |
1984年 | 31篇 |
1983年 | 21篇 |
1982年 | 26篇 |
1981年 | 23篇 |
1980年 | 18篇 |
1979年 | 15篇 |
1978年 | 7篇 |
1977年 | 7篇 |
1974年 | 4篇 |
1971年 | 3篇 |
排序方式: 共有3106条查询结果,搜索用时 15 毫秒
161.
162.
163.
164.
165.
166.
Guinevere Kauffmann Timothy M. Heckman Simon D. M. White Stéphane Charlot Christy Tremonti Jarle Brinchmann Gustavo Bruzual Eric W. Peng Mark Seibert Mariangela Bernardi Michael Blanton Jon Brinkmann Francisco Castander Istvan Csábai Masataka Fukugita Zeljko Ivezic Jeffrey A. Munn Robert C. Nichol Nikhil Padmanabhan Aniruddha R. Thakar David H. Weinberg Donald York 《Monthly notices of the Royal Astronomical Society》2003,341(1):33-53
167.
Mark Cropper M. Barlow M. A. C. Perryman Keith Horne R. Bingham M. Page P. Guttridge A. Smith A. Peacock D. Walker P. Charles 《Monthly notices of the Royal Astronomical Society》2003,344(1):33-44
We describe a multi-order spectrograph concept suitable for 8-m class telescopes, using the intrinsic spectral resolution of superconducting tunnelling junction detectors to sort the spectral orders. The spectrograph works at low orders, 1–5 or 1–6, and provides spectral coverage with a resolving power of R ≃ 8000 from the atmospheric cut-off at 320 nm to the long-wavelength end of the infrared H or K band at 1800 nm or 2400 nm. We calculate that the spectrograph would provide substantial throughput and wavelength coverage, together with high time resolution and sufficient dynamic range. The concept uses currently available technology, or technologies with short development horizons, restricting the spatial sampling to two linear arrays; however, an upgrade path to provide more spatial sampling is identified. All of the other challenging aspects of the concept – the cryogenics, thermal baffling and magnetic field biasing – are identified as being feasible. 相似文献
168.
169.
Darren Reed Jeffrey Gardner Thomas Quinn Joachim Stadel Mark Fardal George Lake Fabio Governato 《Monthly notices of the Royal Astronomical Society》2003,346(2):565-572
We use a high-resolution ΛCDM numerical simulation to calculate the mass function of dark matter haloes down to the scale of dwarf galaxies, back to a redshift of 15, in a 50 h −1 Mpc volume containing 80 million particles. Our low-redshift results allow us to probe low-σ density fluctuations significantly beyond the range of previous cosmological simulations. The Sheth & Tormen mass function provides an excellent match to all of our data except for redshifts of 10 and higher, where it overpredicts halo numbers increasingly with redshift, reaching roughly 50 per cent for the 1010 –1011 M⊙ haloes sampled at redshift 15. Our results confirm previous findings that the simulated halo mass function can be described solely by the variance of the mass distribution, and thus has no explicit redshift dependence. We provide an empirical fit to our data that corrects for the overprediction of extremely rare objects by the Sheth & Tormen mass function. This overprediction has implications for studies that use the number densities of similarly rare objects as cosmological probes. For example, the number density of high-redshift ( z ≃ 6) QSOs , which are thought to be hosted by haloes at 5σ peaks in the fluctuation field, are likely to be overpredicted by at least a factor of 50 per cent. We test the sensitivity of our results to force accuracy, starting redshift and halo-finding algorithm. 相似文献
170.
Wyatt Mark C. Holland Wayne S. Greaves Jane S. Dent William R. F. 《Earth, Moon, and Planets》2003,92(1-4):423-434
Debris disks are found around some 15% of main sequencestars and their dust is thought to be continuallyreplenished in collisions between planetesimals inextrasolar Kuiper belts.While they were discovered in 1984 by IRAS, it is onlywith more recent imaging that their true nature has beenrevealed. This paper discusses recent debris disk images andtheir impact on our understanding of extrasolar systems.Importantly these images confirm the extrasolar Kuiper belthypothesis for most (but not all) debris diskcandidates and show that the planetesimals within thesedisks must have grown to at least a few km.Asymmetries in imaged disk structures also provide informationabout the planetary systems orbiting inside these planetesimalbelts. The impact of debris disk studies on our understandingof the evolution of our own Kuiper belt, as well as theirpotential to solve puzzles such as the origin of the missingmass and the outer edge of the Kuiper belt, is alsodiscussed. 相似文献