全文获取类型
收费全文 | 1675篇 |
免费 | 83篇 |
国内免费 | 16篇 |
专业分类
测绘学 | 24篇 |
大气科学 | 82篇 |
地球物理 | 407篇 |
地质学 | 456篇 |
海洋学 | 121篇 |
天文学 | 416篇 |
自然地理 | 268篇 |
出版年
2021年 | 19篇 |
2020年 | 14篇 |
2019年 | 22篇 |
2018年 | 25篇 |
2017年 | 28篇 |
2016年 | 54篇 |
2015年 | 32篇 |
2014年 | 36篇 |
2013年 | 83篇 |
2012年 | 34篇 |
2011年 | 60篇 |
2010年 | 49篇 |
2009年 | 87篇 |
2008年 | 87篇 |
2007年 | 82篇 |
2006年 | 82篇 |
2005年 | 68篇 |
2004年 | 75篇 |
2003年 | 58篇 |
2002年 | 68篇 |
2001年 | 54篇 |
2000年 | 42篇 |
1999年 | 36篇 |
1998年 | 57篇 |
1997年 | 39篇 |
1996年 | 24篇 |
1995年 | 21篇 |
1994年 | 30篇 |
1993年 | 22篇 |
1992年 | 16篇 |
1991年 | 29篇 |
1990年 | 18篇 |
1989年 | 19篇 |
1988年 | 18篇 |
1987年 | 21篇 |
1986年 | 17篇 |
1985年 | 29篇 |
1984年 | 20篇 |
1983年 | 14篇 |
1982年 | 20篇 |
1981年 | 15篇 |
1980年 | 13篇 |
1979年 | 15篇 |
1978年 | 9篇 |
1977年 | 16篇 |
1976年 | 9篇 |
1975年 | 12篇 |
1973年 | 9篇 |
1972年 | 13篇 |
1971年 | 7篇 |
排序方式: 共有1774条查询结果,搜索用时 111 毫秒
191.
The 2dF Galaxy Redshift Survey: the bJ -band galaxy luminosity function and survey selection function
Peder Norberg Shaun Cole Carlton M. Baugh Carlos S. Frenk Ivan Baldry Joss Bland-Hawthorn Terry Bridges Russell Cannon Matthew Colless Chris Collins Warrick Couch Nicholas J. G. Cross Gavin Dalton Roberto De Propris Simon P. Driver George Efstathiou Richard S. Ellis Karl Glazebrook Carole Jackson Ofer Lahav Ian Lewis Stuart Lumsden Steve Maddox Darren Madgwick John A. Peacock Bruce A. Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2002,336(3):907-931
192.
Liliana Formiggini Noah Brosch Elchanan Almoznino Stuart Bowyer Michael Lampton 《Monthly notices of the Royal Astronomical Society》2002,332(2):441-455
We present results of an analysis of a UV image in the direction of Ophiuchus, obtained with the FAUST instrument. The image contains 228 UV sources. Most of these are identified as normal early-type stars through correlations with catalogued objects. For the first time in this project we identify UV sources as such stars by selecting suitable candidates in crowded fields as the bluest objects in colour–colour diagrams using observations from the Wise Observatory. These candidates are then studied using low-resolution spectroscopy, which allows the determination of spectral types to an accuracy of about one-half class, for 60 stars.
Synthetic photometry of spectral data is performed in order to predict the expected UV emission, on the basis of the photometric information. These results are used along with the Hipparcos /Tycho information, to search for subluminous stars. The comparison of the predicted emission with the FAUST measured magnitudes allows us to select 12 stars as highly probable evolved hot stars. High signal-to-noise spectra are obtained for nine of these stars, and Balmer line profiles are compared with the prediction of atmosphere models and with the spectrum of real stellar atmospheres. Among the nine candidates, six are classified as previously unrecognized sdB stars, and two as white dwarfs. Our result indicates that indeed more bright subluminous stars are still unrecognized in the existing samples. 相似文献
Synthetic photometry of spectral data is performed in order to predict the expected UV emission, on the basis of the photometric information. These results are used along with the Hipparcos /Tycho information, to search for subluminous stars. The comparison of the predicted emission with the FAUST measured magnitudes allows us to select 12 stars as highly probable evolved hot stars. High signal-to-noise spectra are obtained for nine of these stars, and Balmer line profiles are compared with the prediction of atmosphere models and with the spectrum of real stellar atmospheres. Among the nine candidates, six are classified as previously unrecognized sdB stars, and two as white dwarfs. Our result indicates that indeed more bright subluminous stars are still unrecognized in the existing samples. 相似文献
193.
Peder Norberg Carlton M. Baugh Ed Hawkins Steve Maddox John A. Peacock Shaun Cole Carlos S. Frenk Joss Bland-Hawthorn Terry Bridges Russell Cannon Matthew Colless Chris Collins Warrick Couch Gavin Dalton Roberto De Propris Simon P. Driver George Efstathiou Richard S. Ellis Karl Glazebrook Carole Jackson Ofer Lahav Ian Lewis Stuart Lumsden Darren Madgwick Bruce A. Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2001,328(1):64-70
We investigate the dependence of the strength of galaxy clustering on intrinsic luminosity using the Anglo-Australian two degree field galaxy redshift survey (2dFGRS). The 2dFGRS is over an order of magnitude larger than previous redshift surveys used to address this issue. We measure the projected two-point correlation function of galaxies in a series of volume-limited samples. The projected correlation function is free from any distortion of the clustering pattern induced by peculiar motions and is well described by a power law in pair separation over the range . The clustering of galaxies in real space is well-fitted by a correlation length and power-law slope . The clustering amplitude increases slowly with absolute magnitude for galaxies fainter than M *, but rises more strongly at higher luminosities. At low luminosities, our results agree with measurements from the Southern Sky Redshift Survey 2 by Benoist et al. However, we find a weaker dependence of clustering strength on luminosity at the highest luminosities. The correlation function amplitude increases by a factor of 4.0 between and −22.5, and the most luminous galaxies are 3.0 times more strongly clustered than L * galaxies. The power-law slope of the correlation function shows remarkably little variation for samples spanning a factor of 20 in luminosity. Our measurements are in very good agreement with the predictions of the hierarchical galaxy formation models of Benson et al. 相似文献
194.
Alexander Deutsch Christian Koeberl Joel D. Blum Bevan M. French Billy P. Glass Richard Grieve Peter Horn Elmar K. Jessberger Gero Kurat Wolf Uwe Reimold Jan Smit Dieter Stöffler Stuart Ross Taylor 《地学学报》1994,6(6):644-650
In a recent article in Terra Nova, Kristan-Tollmann and Tollmann (1994) suggested that the Biblical Flood can be explained by seven fragments of a comet that impacted the ocean at seven locations on Earth at 03.00h (C.E.T.) on 23 September, 9545 yr BP. We demonstrate that all the ‘geological proofs’ that allegedly support their conclusions are not supported by the available data on impact cratering. Their hypothesis is based on insufficient and ambiguous data, selective citation, and incomplete comprehension of previous research. 相似文献
195.
Complex component analysis of shear-wave splitting: theory 总被引:2,自引:0,他引:2
196.
Donald S. Mussel White Heather A. Dalton Walter S. Kiefer Allan H. Treiman 《Meteoritics & planetary science》2006,41(9):1271-1290
Abstract— The Martian meteorite Yamato (Y‐) 980459 is an olivine‐phyric shergottite. It has a very primitive character and may be a primary melt of the Martian mantle. We have conducted crystallization experiments on a synthetic Y‐980459 composition at Martian upper mantle conditions in order to test the primary mantle melt hypothesis. Results of these experiments indicate that the cores of the olivine megacrysts in Y‐980459 are in equilibrium with a melt of bulk rock composition, suggesting that these megacrysts are in fact phenocrysts that grew from a magma of the bulk rock composition. Multiple saturation of the melt with olivine and a low‐calcium pyroxene occurs at approximately 12 ± 0.5 kbar and 1540 ± 10°C, suggesting that the meteorite represents a primary melt that separated from its mantle source at a depth of ?100 km. Several lines of evidence suggest that the Y‐980459 source underwent extensive melting prior to and/or during the magmatic event that produced the Y‐980459 parent magma. When factored into convective models of the Martian interior, the high temperature indicated for the upper Martian mantle and possibly high melt fraction for the Y‐980459 magmatic event suggests a significantly higher temperature at the core‐mantle boundary than previously estimated. 相似文献
197.
Ian Lewis Michael Balogh Roberto De Propris Warrick Couch Richard Bower Alison Offer Joss Bland-Hawthorn Ivan K. Baldry Carlton Baugh Terry Bridges Russell Cannon Shaun Cole Matthew Colless Chris Collins Nicholas Cross Gavin Dalton Simon P. Driver George Efstathiou Richard S. Ellis Carlos S. Frenk Karl Glazebrook Edward Hawkins Carole Jackson Ofer Lahav Stuart Lumsden Steve Maddox Darren Madgwick Peder Norberg John A. Peacock Will Percival Bruce A. Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2002,334(3):673-683
198.
V. R. Eke Carlos S. Frenk Carlton M. Baugh Shaun Cole Peder Norberg John A. Peacock Ivan K. Baldry Joss Bland-Hawthorn Terry Bridges Russell Cannon Matthew Colless Chris Collins Warrick Couch Gavin Dalton Roberto de Propris Simon P. Driver George Efstathiou Richard S. Ellis Karl Glazebrook Carole A. Jackson Ofer Lahav Ian Lewis Stuart Lumsden Steve J. Maddox Darren Madgwick Bruce A. Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2004,355(3):769-784
199.
200.
Mathematical Geosciences - This paper addresses the problem of finding parametric constraints that ensure the validity of the multivariate Matérn covariance for modeling the spatial... 相似文献