全文获取类型
收费全文 | 10732篇 |
免费 | 1995篇 |
国内免费 | 1715篇 |
专业分类
化学 | 6321篇 |
晶体学 | 78篇 |
力学 | 694篇 |
综合类 | 111篇 |
数学 | 1096篇 |
物理学 | 6142篇 |
出版年
2024年 | 13篇 |
2023年 | 129篇 |
2022年 | 226篇 |
2021年 | 365篇 |
2020年 | 444篇 |
2019年 | 386篇 |
2018年 | 353篇 |
2017年 | 406篇 |
2016年 | 413篇 |
2015年 | 423篇 |
2014年 | 570篇 |
2013年 | 925篇 |
2012年 | 685篇 |
2011年 | 687篇 |
2010年 | 574篇 |
2009年 | 684篇 |
2008年 | 741篇 |
2007年 | 762篇 |
2006年 | 735篇 |
2005年 | 631篇 |
2004年 | 592篇 |
2003年 | 507篇 |
2002年 | 463篇 |
2001年 | 348篇 |
2000年 | 388篇 |
1999年 | 292篇 |
1998年 | 277篇 |
1997年 | 246篇 |
1996年 | 150篇 |
1995年 | 140篇 |
1994年 | 137篇 |
1993年 | 109篇 |
1992年 | 106篇 |
1991年 | 86篇 |
1990年 | 65篇 |
1989年 | 45篇 |
1988年 | 57篇 |
1987年 | 40篇 |
1986年 | 34篇 |
1985年 | 39篇 |
1984年 | 19篇 |
1983年 | 15篇 |
1982年 | 31篇 |
1981年 | 20篇 |
1980年 | 17篇 |
1979年 | 14篇 |
1978年 | 15篇 |
1977年 | 13篇 |
1976年 | 9篇 |
1973年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
In this paper we outline a new particle-mesh method for rapidly rotating shallow water flows based on a set of regularized equations of motion. The time-stepping method uses an operator splitting of the equations into an Eulerian gravity wave part and a Lagrangian advection part. An essential ingredient is the advection of absolute vorticity by means of translated radial basis functions. We show that this implies exact conservation of enstrophy. The method is tested on two model problems based on the qualitative features of the solutions obtained (i.e., dispersion or smoothness of potential vorticity contours) as well as on the increase in mean divergence level. 相似文献
102.
S. C. Joshi M. P. Singh V. P. Pandey B. S. Rajput 《International Journal of Theoretical Physics》2002,41(6):1107-1125
In four-dimensional N = 4 supersymmetric gauge theory, we obtain an exact metric on the moduli space of quantum vacua and analyze the spectra of BPS states in weak as well as in strong coupling regions. Identifying the hypermultiplet of the dyonic state as a string stretched between D3-brane probe and a 7-brane, we demonstrate that the two hypermultiplets, which become massless at two singularities in supersymmetric theory, correspond to open strings beginning on the D3-brane and ending on the respective 7-brane. 相似文献
103.
We obtain a necessary and sufficient condition for the decomposition of the spectrum of an arbitrary nonsymmetric potential whose least value is attained at finitely many points. 相似文献
104.
Experiments employing photoreflectance spectroscopy have uncovered band bending due to electrically active defects at the Si(1 1 1)–SiO2 interface after sub-keV Ar+ ion bombardment. The band bending of about 0.5 eV resembles that for Si(1 0 0)–SiO2, and both interfaces exhibit two kinetic regimes for the evolution of band bending upon annealing due to defects healing. The healing takes place about an order of magnitude more quickly at the (1 1 1) interface, however, probably because of less fully saturated bonding and higher compressive stress. 相似文献
105.
Yu. M. Kargin E. I. Gritsenko V. V. Yanilkin V. V. Plemenkov L. K. Dubovik N. I. Maksimyuk B. M. Garifullin Sh. K. Letypov A. V. Il'yasov 《Russian Chemical Bulletin》1992,41(9):1572-1579
The electrochemical reduction of 1,1-dihalo-2-R-2-methylcyclopropanes was studied by polarography and preparative electrolysis. A mixture of stereoisomeric monoboro- and monochlorocyclopropanes was obtained with preparative yield of 60–70% in preparative electroreduction in methanol against a background of 0.1 M LiClO4. In the case of bromine derivatives of cyclopropanes (except when R = CN) an effect was found on the part of the current density on the ratio of cis and trans isomers, which was interpreted as a change, in dependence on current density, of the contributions of the reactions of reduction of the starting compounds (SN2 mechanism) and ionic pairs (SN1 mechanism). The effect of the solvent (CHCl3, DMF, DMSO, MeOH) and background salt (LiClO4, Et4NBr) on the ratio of stereoisomers is in agreement with this interpretation.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Science Center, Russian Academy of Sciences, Kazan. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 2023–2032, September, 1992. 相似文献
106.
本文提出一种利用材料Hugoniot数据研究高压下离子晶体中微观离子状态及其离子间排斥作用势的新方法。对氢化锂晶体进行研究时,我们得到Li~+和H~-离子之间排斥作用势函数,结果表明文献〔1〕中提出的离子压缩效应具有客观性。 相似文献
107.
本文用ab initio计算方法,采用STO-3G基组,对二硝基卤代甲烷CH_2(NO_2)_3(1),CF_2(NO_2)_2(2);CCl_2(NO_2)_2(3)等分子作了单点计算,研究其旋转势能.全构型优化研究了五个具有对称性构型的结构和稳定性,并作了理论分析和探讨. 相似文献
108.
We have calculated total and differential cross-sections for 1s →ns (n = 2, 3, 4) electron impact excitation of hydrogen and hydrogenic ions at various energies in Coulomb-projected Born approximation.
Distortion due to static interactions, target polarization and exchange effects has been incorporated in the initial channel.
The present calculations have been compared with other theoretical and experimental results. 相似文献
109.
本文在Skyr}e相互作用、核物质近似和自洽半经典方法的基础上,将微观光学势的自洽研究推J“到中能区(60-r300MeV),研究了”+907r在该能区光学势的径向形状和温度效应 相似文献
110.
电磁继电器触点参数的测试 总被引:1,自引:0,他引:1
本文介绍了电磁继电器触点电参数的测试方法,包括接触电阻、绝缘电阻参数测试。 相似文献