全文获取类型
收费全文 | 10329篇 |
免费 | 415篇 |
国内免费 | 81篇 |
专业分类
化学 | 7376篇 |
晶体学 | 62篇 |
力学 | 140篇 |
数学 | 1552篇 |
物理学 | 1695篇 |
出版年
2023年 | 63篇 |
2022年 | 96篇 |
2021年 | 115篇 |
2020年 | 217篇 |
2019年 | 178篇 |
2018年 | 106篇 |
2017年 | 87篇 |
2016年 | 279篇 |
2015年 | 222篇 |
2014年 | 266篇 |
2013年 | 503篇 |
2012年 | 534篇 |
2011年 | 610篇 |
2010年 | 372篇 |
2009年 | 330篇 |
2008年 | 554篇 |
2007年 | 540篇 |
2006年 | 551篇 |
2005年 | 515篇 |
2004年 | 426篇 |
2003年 | 326篇 |
2002年 | 385篇 |
2001年 | 184篇 |
2000年 | 189篇 |
1999年 | 163篇 |
1998年 | 168篇 |
1997年 | 150篇 |
1996年 | 161篇 |
1995年 | 133篇 |
1994年 | 156篇 |
1993年 | 138篇 |
1992年 | 116篇 |
1991年 | 113篇 |
1990年 | 96篇 |
1989年 | 78篇 |
1988年 | 68篇 |
1987年 | 68篇 |
1986年 | 57篇 |
1985年 | 111篇 |
1984年 | 98篇 |
1983年 | 67篇 |
1982年 | 105篇 |
1981年 | 90篇 |
1980年 | 77篇 |
1979年 | 95篇 |
1978年 | 87篇 |
1977年 | 79篇 |
1976年 | 88篇 |
1975年 | 63篇 |
1973年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
We give a common generalization of P. Seymour's “Integer sum of circuits” theorem and the first author's theorem on decomposition of planar Eulerian graphs into circuits without forbidden transitions. 相似文献
993.
Cristian Lenart Frank Sottile 《Proceedings of the American Mathematical Society》2003,131(11):3319-3328
We define skew Schubert polynomials to be normal form (polynomial) representatives of certain classes in the cohomology of a flag manifold. We show that this definition extends a recent construction of Schubert polynomials due to Bergeron and Sottile in terms of certain increasing labeled chains in Bruhat order of the symmetric group. These skew Schubert polynomials expand in the basis of Schubert polynomials with nonnegative integer coefficients that are precisely the structure constants of the cohomology of the complex flag variety with respect to its basis of Schubert classes. We rederive the construction of Bergeron and Sottile in a purely combinatorial way, relating it to the construction of Schubert polynomials in terms of rc-graphs.
994.
995.
996.
Frank Jochmann 《Journal of Differential Equations》2009,246(6):2151-513
This paper deals with a class of first-order systems with generally multivalued damping terms including Bean's model for superconductors with displacement current. The main goal is to prove the convergence of solutions to stationary states as t→∞. 相似文献
997.
Frank Wolter 《Mathematical Logic Quarterly》1996,42(1):145-171
998.
Lianxiang Yang Wolfgang Steinchen Gerhard Kupfer Peter Mäckel Frank Vössing 《Optics and Lasers in Engineering》1998,30(2):199-212
Digital shearography, also called digital speckle pattern shearing interferometry, is described as a robust measuring method due to its simple optical setup and the relative insensitivity against ambient noise. It has been applied for nondestructive testing and strain measuring. This paper explores its possibilities for vibration analysis. The measuring device performing both continuous (time-average method) and stroboscopic illuminations is described. The selection of the illumination mode is made by adjusting a controller and performed simply by a computer. The real-time observation with refreshing reference frame technique and the quantitative evaluation with the phase shift technique are presented. The results show this measuring device is well suited for both qualitative and quantitative vibration analysis. 相似文献
999.
Jong‐Beom Baek Frank W. Harris 《Journal of polymer science. Part A, Polymer chemistry》2005,43(24):6465-6479
A series of extended 6‐substituted quinoxaline AB monomer mixtures, 2‐(4‐fluorophenyl)‐3‐[4‐(4‐hydroxyphenoxy)phenyl]‐6‐substituted quinoxaline and 3‐(4‐fluorophenyl)‐2‐[4‐(4‐hydroxyphenoxy)phenyl]‐6‐substituted quinoxaline, were prepared and polymerized to afford phenylquinoxaline oligomers. High‐molecular‐weight polymers could not be obtained because of the formation of cyclic oligomers. On the basis of matrix‐assisted laser desorption/ionization time‐of‐flight analysis and molecular modeling results, the formation of a cyclic dimer could be a favorable process resulting in low‐molecular‐weight oligomers. They were completely soluble and amorphous, with glass‐transition temperatures varying from 165 to 266 °C, and they had thermooxidative stability, with samples displaying 5% weight loss temperatures of 419–511 °C in nitrogen. The thermal properties of the monomers and resultant polymers dramatically depended on the polarity of the substituents. The monomers and resultant oligomers displayed high fluorescence in tetrahydrofuran solutions and N‐methyl‐2‐pyrrolidinone solutions, respectively. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6465–6479, 2005 相似文献
1000.