全文获取类型
收费全文 | 74385篇 |
免费 | 2694篇 |
国内免费 | 216篇 |
专业分类
化学 | 48396篇 |
晶体学 | 405篇 |
力学 | 1989篇 |
综合类 | 4篇 |
数学 | 12262篇 |
物理学 | 14239篇 |
出版年
2023年 | 510篇 |
2022年 | 681篇 |
2021年 | 968篇 |
2020年 | 1044篇 |
2019年 | 1062篇 |
2018年 | 1349篇 |
2017年 | 1160篇 |
2016年 | 2268篇 |
2015年 | 1999篇 |
2014年 | 2095篇 |
2013年 | 4171篇 |
2012年 | 4692篇 |
2011年 | 5049篇 |
2010年 | 3051篇 |
2009年 | 2665篇 |
2008年 | 4353篇 |
2007年 | 4318篇 |
2006年 | 3944篇 |
2005年 | 3778篇 |
2004年 | 3155篇 |
2003年 | 2612篇 |
2002年 | 2318篇 |
2001年 | 1415篇 |
2000年 | 1214篇 |
1999年 | 917篇 |
1998年 | 721篇 |
1997年 | 709篇 |
1996年 | 830篇 |
1995年 | 598篇 |
1994年 | 627篇 |
1993年 | 620篇 |
1992年 | 652篇 |
1991年 | 543篇 |
1990年 | 532篇 |
1989年 | 470篇 |
1988年 | 430篇 |
1987年 | 439篇 |
1986年 | 371篇 |
1985年 | 620篇 |
1984年 | 548篇 |
1983年 | 400篇 |
1982年 | 514篇 |
1981年 | 472篇 |
1980年 | 426篇 |
1979年 | 400篇 |
1978年 | 386篇 |
1976年 | 399篇 |
1975年 | 359篇 |
1974年 | 331篇 |
1973年 | 343篇 |
排序方式: 共有10000条查询结果,搜索用时 5 毫秒
81.
Clément Gallo 《Comptes Rendus Mathematique》2006,342(5):319-323
We give an upper bound on the growth rate of the Schrödinger group on Zhidkov spaces. In dimension 1, we prove that this bound is sharp. To cite this article: C. Gallo, C. R. Acad. Sci. Paris, Ser. I 342 (2006). 相似文献
82.
J. Carlos Díaz-Ramos Ramón Vázquez-Lorenzo 《Differential Geometry and its Applications》2006,24(4):433-442
Explicit examples of Osserman 4-manifolds with exactly two distinct eigenvalues of the Jacobi operators, α and β=4α≠0, are given. The former has multiplicity two and is a double root of the minimal polynomial of the Jacobi operators. 相似文献
83.
We study the asymptotic properties of the Bayes estimator in models differentiable in quadratic mean (DQM) in the case of
independent and identically distributed observations. The goal is to define weak assumptions on the model under which this
estimator is asymptotically efficient, regular, and asymptotically of minimal risk. The results of the paper are applied to
models based on a mixture distribution, the Cauchy distribution with location and scale parameter, and the Weibull distribution.
Bibliography: 10 titles.
Published in Zapiski Nauchnykh Seminarov POMI, Vol. 328, 2005, pp. 114–146. 相似文献
84.
A. I. Magunov A. Ya. Faenov I. Yu. Skobelev T. A. Pikuz E. Biémont P. Quinet F. Blasco C. Bonte F. Dorchies T. Caillaud F. Salin C. Stenz 《Journal of Experimental and Theoretical Physics》2002,95(6):998-1005
The satellite structure of 1s2p 1,3 P 1-1s 21 S 0 lines of the He-like argon ion in plasma produced by a 45-fs laser pulse in a gas-jet cluster target is measured with a high spectral resolution. Radiation transitions 2p → 1s from autoionizing states (AISs) are detected for ions ranging from Li-like to F-like. The spectrum observed is theoretically simulated with the use of the spectroscopic data for the AISs of multicharged ions obtained within the multiconfiguration relativistic Hartree-Fock method. Good agreement with experimental data is obtained when the main population channels of these states are taken into account for typical values of cluster-target plasma parameters. 相似文献
85.
Michel Hébert 《Archive for Mathematical Logic》1991,31(2):133-143
Summary We give a syntactic characterization of (finitary) theories whose categories of models are closed under the formation of connected limits (respectively the formation of pullbacks and substructures) in the category of all structures. They are also those theories whose consistent extensions by new atomic facts admit in each component an initial structure (respectively an initial term structure), and also thoseT for whichM(T) is locally finitely multi-presentable in a canonical way. We also show that these two properties of theories are nonuniform. 相似文献
86.
87.
In this Note, we study a 2×2 system of evolution equations with some codimension 3 crossing. We derive two conditions of non-degeneracy. We focus on one of them and reduce our system to some Landau–Zener's type system. Using this reduction, we describe the energy transfer at the crossing by Landau–Zener formula for 2-scales semi-classical measures. To cite this article: C. Fermanian Kammerer, P. Gérard, C. R. Acad. Sci. Paris, Ser. I 335 (2002) 915–920. 相似文献
88.
89.
Gábor Dörnyei Marietta Bárczai-Beke Gábor Blaskó Péter Péchy Csaba Szántay 《Tetrahedron letters》1982,23(28):2913-2916
Regioselective demethylation of 3,4-dihydropapaveraldine (a) at 7 and 3' positions affords a properly substituted diphenolic key intermidiate (d) for the synthesis of reticuline and N-norreticuline. 相似文献
90.
A. Guzmn E. Luna J. Miguel-Snchez E. Calleja E. Muoz 《Infrared Physics & Technology》2003,44(5-6):377-382
In this work, we report on the design, growth and characterization of GaAsN/AlAs/AlGaAs double barrier quantum well infrared detectors to achieve intraband absorption below 4 μm. Due to the high effective mass of N-dilute alloys, it is common for these N-containing double barrier quantum well structures to have more than one bound state within the quantum well, enabling the possibility of achieving multispectral absorption from these confined levels to the quasi-bound. Based on a transfer matrix calculation we will study the influence of the potential parameters, in particular the well width and the introduction of a GaAs spacer layer in between the N-well and the AlAs barriers. We will compare the case in which there are two confined levels with the case in which only one level is bound, like in the conventional AlGaAs/AlAs/GaAs structures. On the basis of the simulation, we have grown and characterized some N-containing double barrier detectors. Moreover, an optimization of the post-growth annealing treatments of the GaAsN quantum well structures has also been performed. Finally, room temperature absorption measurements of both as-grown and annealed samples are presented and analyzed. 相似文献