全文获取类型
收费全文 | 344813篇 |
免费 | 6660篇 |
国内免费 | 4081篇 |
专业分类
化学 | 175497篇 |
晶体学 | 4298篇 |
力学 | 17174篇 |
综合类 | 231篇 |
数学 | 62938篇 |
物理学 | 95416篇 |
出版年
2021年 | 2324篇 |
2020年 | 2832篇 |
2019年 | 2901篇 |
2018年 | 13326篇 |
2017年 | 13207篇 |
2016年 | 11070篇 |
2015年 | 4707篇 |
2014年 | 5582篇 |
2013年 | 12086篇 |
2012年 | 14108篇 |
2011年 | 22265篇 |
2010年 | 14007篇 |
2009年 | 13909篇 |
2008年 | 17491篇 |
2007年 | 19527篇 |
2006年 | 10843篇 |
2005年 | 10980篇 |
2004年 | 10015篇 |
2003年 | 9390篇 |
2002年 | 8384篇 |
2001年 | 8202篇 |
2000年 | 6289篇 |
1999年 | 4559篇 |
1998年 | 3878篇 |
1997年 | 3750篇 |
1996年 | 3926篇 |
1995年 | 3384篇 |
1994年 | 3460篇 |
1993年 | 3294篇 |
1992年 | 3514篇 |
1991年 | 3425篇 |
1990年 | 3183篇 |
1989年 | 3079篇 |
1988年 | 2968篇 |
1987年 | 2898篇 |
1986年 | 2874篇 |
1985年 | 3831篇 |
1984年 | 3865篇 |
1983年 | 3218篇 |
1982年 | 3486篇 |
1981年 | 3236篇 |
1980年 | 3023篇 |
1979年 | 3198篇 |
1978年 | 3373篇 |
1977年 | 3387篇 |
1976年 | 3392篇 |
1975年 | 3123篇 |
1974年 | 3213篇 |
1973年 | 3233篇 |
1972年 | 2474篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
We give a concise review and extension of S-procedure that is an instrumental tool in control theory and robust optimization analysis. We also discuss the approximate S-Lemma as well as its applications in robust optimization.The many suggestions and detailed corrections of an anonymous referee are gratefully acknowledged. 相似文献
992.
993.
994.
995.
996.
997.
Ion synthesis and laser annealing of Cu nanoparticles in Al2O3 总被引:1,自引:0,他引:1
A.L. Stepanov V.N. Popok D.E. Hole I.B. Khaibullin 《Applied Physics A: Materials Science & Processing》2002,74(3):441-446
Al2O3 samples with Cu nanoparticles, synthesised by ion implantation at 40 keV with a dose of 1×1017 ion/cm2 and a current density from 2.5 to 12.5 μA/cm2, were annealed using ten pulses from a KrF excimer laser with a single pulse fluence of 0.3 J/cm2. The copper depth distribution, formation and modification of metal nanoparticles under the ion implantation and laser treatment
were studied by Rutherford backscattering (RBS), energy dispersive X-ray (EDX) analysis, atomic force microscopy (AFM) and
optical spectroscopy. It was found that laser annealing leads to a reduction in the nanoparticle size without diffusion of
metal atoms into the bulk. The change in particle size and the possibility for oxidation of the copper particles are examined
in the framework of Mie theory. Calculations presented show that under excimer laser treatment, Cu nanoparticles are more
likely to be reduced in size than to undergo oxidation.
Received: 19 April 2001 / Accepted: 7 November 2001 / Published online: 23 January 2002 相似文献
998.
Ph. Hägler B. Pire L. Szymanowski O.V. Teryaev 《The European Physical Journal C - Particles and Fields》2002,24(2):261-270
We study Pomeron-Odderon interference effects giving rise to charge and single-spin asymmetries in diffractive electroproduction
of a pair. We calculate these asymmetries, originating from both longitudinal and transverse polarizations of the virtual photon,
in the framework of QCD and in the Born approximation, in a kinematical domain accessible to HERA experiments. We predict
a sizable charge asymmetry with a characteristic dependence on the invariant mass of the pair, which makes this observable very important for establishing the magnitude of the Odderon exchange in hard processes.
The single-spin asymmetry turns out to be rather small. We briefly discuss future improvements of our calculations and their
possible effects on the results.
Received: 18 July 2002 / Published online: 25 October 2002 相似文献
999.
1000.
P G Stelmachowicz D E Lewis L L Larson W Jesteadt 《The Journal of the Acoustical Society of America》1987,81(6):1881-1887
Growth-of-masking functions were obtained from 19 normal and 5 hearing-impaired listeners using a simultaneous-masking paradigm. When masker and probe frequency are identical, the slope of masking approximates 1.0 for both normal-hearing and impaired listeners. For masker frequencies less than or greater than probe frequency, the slopes for impaired listeners are shallower than those of normals. These findings are consistent with previously reported physiological data (single-fiber rate versus level and AP masking functions) for animals with induced cochlear lesions. Results are discussed in terms of a potential masking technique to estimate the growth of response in normal and impaired ears. 相似文献