全文获取类型
收费全文 | 3401篇 |
免费 | 86篇 |
国内免费 | 7篇 |
专业分类
化学 | 2334篇 |
晶体学 | 42篇 |
力学 | 68篇 |
数学 | 356篇 |
物理学 | 694篇 |
出版年
2022年 | 18篇 |
2021年 | 37篇 |
2020年 | 50篇 |
2019年 | 40篇 |
2018年 | 26篇 |
2017年 | 27篇 |
2016年 | 47篇 |
2015年 | 52篇 |
2014年 | 71篇 |
2013年 | 163篇 |
2012年 | 148篇 |
2011年 | 201篇 |
2010年 | 119篇 |
2009年 | 83篇 |
2008年 | 181篇 |
2007年 | 199篇 |
2006年 | 196篇 |
2005年 | 194篇 |
2004年 | 177篇 |
2003年 | 134篇 |
2002年 | 131篇 |
2001年 | 62篇 |
2000年 | 47篇 |
1999年 | 37篇 |
1998年 | 35篇 |
1997年 | 43篇 |
1996年 | 41篇 |
1995年 | 39篇 |
1994年 | 52篇 |
1993年 | 58篇 |
1992年 | 33篇 |
1991年 | 41篇 |
1990年 | 37篇 |
1989年 | 29篇 |
1988年 | 30篇 |
1987年 | 21篇 |
1986年 | 23篇 |
1985年 | 31篇 |
1984年 | 46篇 |
1983年 | 29篇 |
1982年 | 49篇 |
1981年 | 37篇 |
1980年 | 29篇 |
1979年 | 35篇 |
1978年 | 36篇 |
1977年 | 29篇 |
1976年 | 38篇 |
1975年 | 28篇 |
1974年 | 30篇 |
1973年 | 23篇 |
排序方式: 共有3494条查询结果,搜索用时 921 毫秒
71.
72.
73.
74.
Weaver M Arisaka K Roberts D Slater W Briere RA Cheu E Harris DA Roodman A Schwingenheuer B Wah YW Winstein B Winston R Barker AR Swallow EC Bock GJ Coleman R Crisler M Enagonia J Ford R Hsiung YB Jensen DA McFarland KS Ramberg E Tschirhart R Collins EM Gollin GD Nakaya T Yamanaka T Gu P Haas P Hogan WP Kim SK Matthews JN Myung SS Schnetzer S Somalwar SV Thomson GB Zou Y 《Physical review letters》1994,72(24):3758-3761
75.
Strachan JD Adler H Alling P Ancher C Anderson H Anderson JL Ashcroft D Barnes CW Barnes G Batha S Bell MG Bell R Bitter M Blanchard W Bretz NL Budny R Bush CE Camp R Caorlin M Cauffman S Chang Z Cheng CZ Collins J Coward G Darrow DS DeLooper J Duong H Dudek L Durst R Efthimion PC Ernst D Fisher R Fonck RJ Fredrickson E Fromm N Fu GY Furth HP Gentile C Gorelenkov N Grek B Grisham LR Hammett G Hanson GR Hawryluk RJ Heidbrink W Herrmann HW Hill KW Hosea J Hsuan H Janos A Jassby DL Jobes FC 《Physical review letters》1994,72(22):3526-3529
76.
Coupled-state calculations including positronium channels are reported for positron scattering by atomic hydrogen, lithium and sodium. Integrated cross sections and total cross sections are presented for all three atoms. For lithium differential cross sections are also given. Throughout, comparison is made between results calculated with and without inclusion of the positronium channels. S-wave cross sections for positron scattering by atomic hydrogen in the Ps(1s, 2s, 2p)+H(1s, 2s, 2p) approximation show the high energy resonance first observed by Higgins and Burke in the coupled-static approximation. This resonance has now moved up to 51.05 eV and narrowed in width to 2.92 eV. Other pronounced structure is seen in the S-wave cross sections between 10 and 20 eV; it is tentatively suggested that this structure may be due to the formation of a temporary pseudo-molecular collision complex. Results calculated in the Ps(1s, 2s,
, 2p,
,+H(1s, 2s,
, 2p,
approximation show convergence towards accurate values in the energy region below and in the Ore gap. Contrary to previous work on lithium using only an atomic basis, it is found that coupling to the 3d state of lithium is not so important when positronium channels are included; this is because a mixed basis of atom and positronium states gives a more rapidly convergent approximation than an expansion based on atom states alone. The threshold behaviour of the elastic cross section and the Ps(1s) formation cross section for lithium is investigated. Results in the Ps(1s, 2s, 2p)+Na(3s, 3p) approximation for sodium show good agreement with the total cross section measurements of Kwan et al. 相似文献
77.
High-purity Fe powder was mechanically milled under argon at ambient temperature using an SPEX 8000 mill. The local atomic and magnetic structure was studied using57Co/Fe Mössbauer and111In/Cd perturbed angular correlations (PAC) spectroscopies. After 32 hours of milling, X-ray diffraction revealed effective grain diameters of 18 nm and energy-dispersive X-ray analysis indicated a Cr impurity concentration of 5%, presumably introduced by mechanical attrition of steel ball bearings used for milling. In addition to a spectral component very similar to bulk iron metal, the Mössbauer spectra exhibited hyperfine field shifts attributed to the Cr impurities. PAC spectra on Fe milled for 5 h, with no contamination, exhibited two components: (1) A slightly broadened magnetic interaction attributed to interior, defect-free sites of In/Cd probes with a mean hyperfine field slightly greater than in macroscopic grains. The defect-free site fraction grew appreciably during milling, even though In is essentially insoluble in Fe. (2) An indistinct signal due to mixed magnetic and quadrupole interactions attributed to probes at surface or other defect sites. 相似文献
78.
Gu P Haas P Hogan WP Kim SK Matthews JN Myung SS Schnetzer S Thomson GB Zou Y Arisaka K Roberts D Slater W Spencer MB Weaver M Briere RA Cheu E Harris DA Krolak P McFarland KS Roodman A Schwingenheuer B Somalwar SV Wah YW Winstein B Winston R Barker AR Swallow EC Bock GJ Coleman R Crisler M Enagonio J Ford R Hsiung YB Jensen DA O'Dell VR Ramberg E Tschirhart R Collins EM Gollin GD Nakaya T Yamanaka T 《Physical review letters》1996,76(23):4312-4315
79.
80.