全文获取类型
收费全文 | 568篇 |
免费 | 7篇 |
国内免费 | 5篇 |
专业分类
化学 | 343篇 |
力学 | 28篇 |
数学 | 48篇 |
物理学 | 161篇 |
出版年
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 16篇 |
2013年 | 20篇 |
2012年 | 23篇 |
2011年 | 21篇 |
2010年 | 14篇 |
2009年 | 9篇 |
2008年 | 23篇 |
2007年 | 25篇 |
2006年 | 33篇 |
2005年 | 21篇 |
2004年 | 23篇 |
2003年 | 19篇 |
2002年 | 15篇 |
2001年 | 9篇 |
2000年 | 22篇 |
1999年 | 6篇 |
1998年 | 12篇 |
1997年 | 7篇 |
1996年 | 16篇 |
1995年 | 6篇 |
1994年 | 10篇 |
1993年 | 7篇 |
1992年 | 11篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1987年 | 4篇 |
1985年 | 13篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1982年 | 11篇 |
1981年 | 9篇 |
1980年 | 13篇 |
1979年 | 9篇 |
1978年 | 17篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1975年 | 8篇 |
1973年 | 7篇 |
1970年 | 4篇 |
1969年 | 4篇 |
1968年 | 4篇 |
1967年 | 4篇 |
1966年 | 4篇 |
1870年 | 4篇 |
排序方式: 共有580条查询结果,搜索用时 15 毫秒
31.
Volume Contents
Contents of Volume 7 (2004) 相似文献32.
A convenient one-pot procedure to prepare angularly substituted bicyclic and tricyclic molecules with excellent diastereoselectivity in good yield was developed, by Fe(CO)5 promoted cyclization. Three transformations (complexation, isomerization, and cyclization) were realized in a single operation. The product of this reaction may be a precursor for synthesis of the alkaloid gelsemine. 相似文献
33.
A methodology for stereocontrol during the intramolecular coupling between cyclohexadiene--Fe(CO)(3) complexes and pendant alkenes is presented. Introduction of a methoxy group at the C(3) position of the diene moiety controls pre- and postcyclization rearrangements of the diene Fe(CO)(3) unit, allowing the preparation of spirolactams with defined relative stereochemistry and with a cyclohexenone framework, thus making this reaction a potentially valuable tool for the construction of quaternary carbon centers. 相似文献
34.
35.
Wilkinson PN Henstock DR Browne IW Polatidis AG Augusto P Readhead AC Pearson TJ Xu W Taylor GB Vermeulen RC 《Physical review letters》2001,86(4):584-587
Using very long baseline interferometry we have searched a sample of 300 compact radio sources for examples of multiple imaging produced by gravitational lensing; no multiple images were found with separations in the angular range 1.5--50 milliarcsec. This null result allows us to place a limit on the cosmological abundance of intergalactic supermassive compact objects in the mass range approximately 10(6)M( middle dot in circle) to approximately 10(8)M( middle dot in circle); such objects cannot make up more than approximately 1% of the closure density ( 95% confidence). A uniformly distributed population of supermassive black holes forming soon after the big bang does not, therefore, contribute significantly to the dark matter content of the Universe. 相似文献
36.
E. Berkove F. T. Farrell D. Juan-Pineda K. Pearson 《Transactions of the American Mathematical Society》2000,352(12):5689-5702
We prove the Farrell-Jones Isomorphism Conjecture for groups acting properly discontinuously via isometries on (real) hyperbolic -space with finite volume orbit space. We then apply this result to show that, for any Bianchi group , , , and vanish for .
37.
Fera A Dolbnya IP Grubel G Muller HG Ostrovskii BI Shalaginov AN de Jeu WH 《Physical review letters》2000,85(11):2316-2319
Coherent dynamic x-ray scattering has been used to study the thermally excited layer fluctuations in freely suspended smectic films of the compound 4O.8. Using 8-keV x rays and films with a thickness around 0.3 &mgr;m we resolve relaxation times down to a few &mgr;s. A combination of damped and oscillatory behavior is observed for the layer undulations, which can be attributed to inertial effects. These are due to the surface contribution to the free energy which cannot be disregarded for thin films. 相似文献
38.
Arwen R. Pearson Reinhard Pahl Elena G. Kovaleva Victor L. Davidson Carrie M. Wilmot 《Journal of synchrotron radiation》2007,14(1):92-98
X‐ray exposure during crystallographic data collection can result in unintended redox changes in proteins containing functionally important redox centers. In order to directly monitor X‐ray‐derived redox changes in trapped oxidative half‐reaction intermediates of Paracoccus denitrificans methylamine dehydrogenase, a commercially available single‐crystal UV/Vis microspectrophotometer was installed on‐line at the BioCARS beamline 14‐BM‐C at the Advanced Photon Source, Argonne, USA. Monitoring the redox state of the intermediates during X‐ray exposure permitted the creation of a general multi‐crystal data collection strategy to generate true structures of each redox intermediate. 相似文献
39.
40.