全文获取类型
收费全文 | 219412篇 |
免费 | 1847篇 |
国内免费 | 653篇 |
专业分类
化学 | 120519篇 |
晶体学 | 3306篇 |
力学 | 8510篇 |
综合类 | 6篇 |
数学 | 23767篇 |
物理学 | 65804篇 |
出版年
2020年 | 2015篇 |
2019年 | 2301篇 |
2018年 | 3228篇 |
2017年 | 3137篇 |
2016年 | 4334篇 |
2015年 | 2426篇 |
2014年 | 3897篇 |
2013年 | 9435篇 |
2012年 | 7056篇 |
2011年 | 8631篇 |
2010年 | 6177篇 |
2009年 | 6012篇 |
2008年 | 8334篇 |
2007年 | 8405篇 |
2006年 | 7803篇 |
2005年 | 7123篇 |
2004年 | 6325篇 |
2003年 | 5823篇 |
2002年 | 5648篇 |
2001年 | 6038篇 |
2000年 | 4801篇 |
1999年 | 3532篇 |
1998年 | 3063篇 |
1997年 | 3084篇 |
1996年 | 2920篇 |
1995年 | 2380篇 |
1994年 | 2477篇 |
1993年 | 2527篇 |
1992年 | 2670篇 |
1991年 | 2721篇 |
1990年 | 2626篇 |
1989年 | 2584篇 |
1988年 | 2537篇 |
1987年 | 2493篇 |
1986年 | 2413篇 |
1985年 | 3107篇 |
1984年 | 3263篇 |
1983年 | 2598篇 |
1982年 | 2874篇 |
1981年 | 2765篇 |
1980年 | 2554篇 |
1979年 | 2784篇 |
1978年 | 2873篇 |
1977年 | 2922篇 |
1976年 | 2889篇 |
1975年 | 2743篇 |
1974年 | 2726篇 |
1973年 | 2868篇 |
1972年 | 1904篇 |
1967年 | 1846篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
141.
A. E. Dorokhov 《Czechoslovak Journal of Physics》2002,52(3):C79-C90
Nonperturbative nolocal structure of QCD vacuum is well described by instanton model. Specific helicity and flavor structure of zero modes of quarks, in instanton field allows simultaneously to explain some important features of low-and high-energy hadron phenomemology. The basic characteristics of hadron spectrum, partonic sum rules, heavyquark potential etc within the instanton liquid model are briefly discussed. 相似文献
142.
We investigate the replica symmetry breaking (RSB) in a neighborhood of the instability point of the replica-symmetric solution in the axial quadrupolar glass model. We show that the solution with the first-stage RSB is stable against the subsequent RSB. Although there is no reflection symmetry, the first-stage RSB solution continuously bifurcates from the replica-symmetric one. This implies that our model does not belong to either of the two classes into which spin glasses are usually divided. 相似文献
143.
The microhardness and content of carbon in electroplated gold coatings were studied as influenced by the operation time of citrate and citrate-phosphate gold-plating electrolytes. Such physicomechanical properties as porosity, microhardness, internal stress, plasticity, and microstructure of electroless-plated and electroplated nickel coatings were studied and analyzed. 相似文献
144.
C. Daum L. Hertzberger W. Hoogland R. Jongerius S. Peters P. Van Deurzen V. Chabaud A. Gonzalez-Arroyo B. Hyams H. Tiecke P. Weilhammer A. Dwurazny G. Polok M. Rozanska K. Rybicki M. Turala J. Turnau G. Ascoli H. Backer G. Blanar M. Cerrada H. Dietl J. Gallivan M. Glaubmann R. Klanner E. Lorenz G. Lütjens G. Lutz W. Männer U. Stierlin I. Blakey M. Bowler R. Cashmore J. Loken W. Spalding G. Thompson B. Alper C. Damerell A. Gillman C. Hardwick M. Hotchkiss F. Wickens ACCMOR Collaboration 《Zeitschrift fur Physik C Particles and Fields》1981,10(2):95-100
Muon electron pairs were detected in an Al multiplate spark chamber, exposed to a neutrino beam from the CERN PS. The leptons were not accompanied by other particles, except occasionally by protons. The background came mainly from muon associated π0 production, with one decay gamma lost. It was determined empirically, together with the small contribution from υ e reactions. For electron energies above 2 GeV the background is 5.7±1.5 events, whereas 18 (μe)-candidates have been observed. Hence the effect is established, with a rate of about 10?4 as compared to the muonic reactions above 3 GeV. Charm creation as the origin of this (μe)-production process is excluded; heavy neutral lepton production does not fit the kinematics observed. Instead the events are compatible with the two-body decay of an object with variable invariant mass of order 1 GeV, possibly resulting from axion interactions. 相似文献
145.
146.
147.
148.
A convenient method is proposed for the synthesis of all the individual methyl ethers of methyl 2-acetamido-2-deoxy-α-D-glucopyranoside based on the partial methylation of 2-acetamido-2-deoxy-α-D-glucopyranoside with dimethyl sulfate in an alkaline medium followed by preparative liquid column chromatography on silica gel of the resulting mixture of methyl ethers. 相似文献
149.
Tricyclic skeletons have been generated from acyclic enyne precursors by using an intramolecular Pauson-Khand reaction in combination with aldol, Michael and alkylation reactions. 相似文献
150.
Mark L. Agranovsky E. K. Narayanan 《Proceedings of the American Mathematical Society》2006,134(7):2117-2123
A test for a function to be a solution of an elliptic PDE is given in terms of extensions, as solutions, from the boundaries inside the domains belonging to an isotopic family. It generalizes a result of Ehrenpreis for spheres moved along a straight line.