全文获取类型
收费全文 | 125059篇 |
免费 | 2507篇 |
国内免费 | 130篇 |
专业分类
化学 | 71917篇 |
晶体学 | 1485篇 |
力学 | 4795篇 |
综合类 | 1篇 |
数学 | 15257篇 |
物理学 | 34241篇 |
出版年
2022年 | 856篇 |
2021年 | 1356篇 |
2020年 | 1630篇 |
2019年 | 1729篇 |
2018年 | 2579篇 |
2017年 | 2482篇 |
2016年 | 3632篇 |
2015年 | 2387篇 |
2014年 | 3084篇 |
2013年 | 6125篇 |
2012年 | 6196篇 |
2011年 | 6657篇 |
2010年 | 4644篇 |
2009年 | 4272篇 |
2008年 | 5893篇 |
2007年 | 5777篇 |
2006年 | 5329篇 |
2005年 | 4931篇 |
2004年 | 4389篇 |
2003年 | 3801篇 |
2002年 | 3637篇 |
2001年 | 3098篇 |
2000年 | 2350篇 |
1999年 | 1763篇 |
1998年 | 1518篇 |
1997年 | 1390篇 |
1996年 | 1358篇 |
1995年 | 1120篇 |
1994年 | 1162篇 |
1993年 | 1168篇 |
1992年 | 1244篇 |
1991年 | 1246篇 |
1990年 | 1181篇 |
1989年 | 1206篇 |
1988年 | 1065篇 |
1987年 | 1012篇 |
1986年 | 948篇 |
1985年 | 1234篇 |
1984年 | 1299篇 |
1983年 | 1044篇 |
1982年 | 1156篇 |
1981年 | 1052篇 |
1980年 | 972篇 |
1979年 | 1036篇 |
1978年 | 1143篇 |
1977年 | 1120篇 |
1976年 | 1068篇 |
1975年 | 1008篇 |
1974年 | 1025篇 |
1973年 | 997篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A forward dispersion calculation is implemented for the spin polarizabilities γ1,,γ4 of the proton and the neutron. These polarizabilities are related to the spin structure of the nucleon at low energies and are structure-constants of the Compton scattering amplitude at
. In the absence of a direct experimental measurement of these quantities, a dispersion calculation serves the purpose of constraining the model building, and of comparing with recent calculations in heavy baryon chiral perturbation theory. 相似文献
992.
Dimeric stilbenes have been isolated from the wood of Amur maackia for the first time. Two of them have been identified as the known scirpusins A and B. The structure of a new dimeric stilbene with a dioxane linkage, which has been called maackinin, has been established. The PMR and13C NMR spectra of the substances isolated have been studied in detail.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, Russian Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 468–476, September–October, 1992. 相似文献
993.
Á. Pintér 《Archiv der Mathematik》1993,61(1):64-67
Research supported in part by Grant 4055 from the Hungarian National Foundation for Scientific Research and by Kereskedelmi és Hitelbank Rt. Universitas Foundation. 相似文献
994.
J.P. Contour A. Défossez D. Ravelosona A. Abert P. Ziemann 《Zeitschrift für Physik B Condensed Matter》1996,100(2):185-190
An energy model has been used to calculate the critical thickness h c of YBaCuO thin films and YBaCuO based superlattices within an isotropic or anisotropic approximation. The critical thickness of single layers calculated from the anisotropic model (16 nm) is in good agreement with the previously published experimental values which are spread out from 4 to 20 nm. In the case of superlattices, relaxation appears to be governed by the critical thickness of the elementary sub-layers and is then better evaluated through the calculation performed for YBaCuO single layers. XRD measurements on YBa2Cu3O7/PrBa2Cu3?xGaxO7 superlattices grown on {100{ SrTiO3 have evidenced a tetragonal stress in the YBaCuO ab plane which remains expanded when the YBaCuO elementary layer thickness is lower than 4.8 nm (4 YBaCuO cells). However the critical temperature of the shortest period superlattices is only slightly affected by this expanded stress in contrast to the effect of an elastic stress externally applied along the ab plane of YBaCuO thin films. 相似文献
995.
I. P. Romanova S. G. Fattakhov A. A. Nafikova I. I. Vandyukova R. R. Shagidullin N. M. Azancheev V. S. Reznik O. G. Sinyáshin 《Russian Chemical Bulletin》1998,47(9):1812-1819
The reactions of phosphine derivatives of diallyl isocyanurates with palladium(ii) dichloride lead to the formation of complexes, whose structure, composition, and stability depend on the length of the methylene
chain between the isocyanurate and diphenylphosphine fragments in the ligand. 1,3-Diallyl-5-[5′-(diphenylphosphino)pentyl
and 10′-(diphenyl-phosphino)decyl] isocyanurates with PdCl2 form monomeric L2PdCl2
trans-complexes in which P atoms of the ligands participate in coordination with the metal. 1,3-Diallyl-5-[2′-(diphenylphosphino)ethyl]
isocyanurate with PdCl2 forms a dimeric (LPdCl2)2 complex, which decomposes in a solution to the monomer including solvent molecule into the coordination sphere of the metal.
The reactions of 1,3-diallyl-5-[4′-(diphenylphosphino)butyl] isocyanurate and 1,3-diallyl-5-[6′-(diphenylphosphino)hexyl]
isocyanurate with PdCl2 give monomeric chelate LPdCl2 complexes in which one of the allyl groups of the isocyanurate cycle participates in coordination with the central ion along
with the phosphorus atom.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1859–1865, September, 1998. 相似文献
996.
997.
A. I. Golovashkin N. V. Anshukova L. I. Ivanova O. T. Maljuchkov A. P. Rusakov 《Czechoslovak Journal of Physics》1996,46(3):1191-1192
On the basis of new experimental studies of specific heat, magnetic properties and thermal expansion, it was shown that dielectric-metal phase transitions were the consequence of delocalization of the heavy holes located on metalapical oxygen bonds in the high-Tc oxide systems. The ordered arrays of such holes (CDW) results in the dielectric gaps in electron spectrum and anomalous negative thermal expansion. The free carriers introduced by doping can couple through excitations of these localized holes, (local bosons). The high-Tc superconductivity will possess anomalous Hc2(T) dependence and γ-type specific heat jump at Tc. This local bosons model is the basis for explanation of the obtained experimental data. 相似文献
998.
999.
We present here a self consistent theory of small amplitude double layers associated with electrostatic ion cyclotron waves in a plasma containing hot electrons, cold ions and traversed by an ion beam. It has been shown that compressive type of double layers solution exists when θb (beam temperature) < αb (beam concentration) < 1. 相似文献
1000.