全文获取类型
收费全文 | 11969篇 |
免费 | 1082篇 |
国内免费 | 970篇 |
专业分类
化学 | 3630篇 |
晶体学 | 29篇 |
力学 | 502篇 |
综合类 | 99篇 |
数学 | 8353篇 |
物理学 | 1408篇 |
出版年
2023年 | 121篇 |
2022年 | 86篇 |
2021年 | 141篇 |
2020年 | 305篇 |
2019年 | 278篇 |
2018年 | 304篇 |
2017年 | 290篇 |
2016年 | 450篇 |
2015年 | 362篇 |
2014年 | 546篇 |
2013年 | 901篇 |
2012年 | 592篇 |
2011年 | 644篇 |
2010年 | 557篇 |
2009年 | 792篇 |
2008年 | 872篇 |
2007年 | 774篇 |
2006年 | 724篇 |
2005年 | 627篇 |
2004年 | 504篇 |
2003年 | 575篇 |
2002年 | 483篇 |
2001年 | 335篇 |
2000年 | 360篇 |
1999年 | 358篇 |
1998年 | 281篇 |
1997年 | 330篇 |
1996年 | 171篇 |
1995年 | 148篇 |
1994年 | 127篇 |
1993年 | 92篇 |
1992年 | 75篇 |
1991年 | 70篇 |
1990年 | 78篇 |
1989年 | 55篇 |
1988年 | 58篇 |
1987年 | 45篇 |
1986年 | 48篇 |
1985年 | 60篇 |
1984年 | 65篇 |
1983年 | 21篇 |
1982年 | 40篇 |
1981年 | 36篇 |
1980年 | 42篇 |
1979年 | 30篇 |
1978年 | 32篇 |
1977年 | 41篇 |
1976年 | 25篇 |
1975年 | 15篇 |
1973年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 921 毫秒
81.
进一步研究了具有三个cM公共值的亚纯函数的唯一性,改进了H.Ueda和仪洪勋等人的有关结果. 相似文献
82.
In this paper, we present some counterexamples which show that there is no theory on the spectrum of homogeneous compact operators which parallels the Riesz-Schauder theory on the spectrum of linear compact operators. These counterexamples also illustrate that it is impossible to study in a unified setting the Fucik spectrum of the Laplacian: -△w = au+ - bu- inΩand u = 0 on (?)Ω, as well as the spectrum of the p-Laplacian: -div(|(?)u| p-2(?)u) = λ|u|p-2u and u = 0 on (?)Ω. 相似文献
83.
Homogeneously prepared tosylcelluloses (TC) with degrees of substitution (DS) of DSTos 0.1–1.8 were used as intermediates for the synthesis of methylaminocelluloses (MAC) by nucleophilic substitution with methylamine. TC with DSTos up to 1.1 were shown to be valuable intermediates for selective synthesis of MAC with DSMA varying from 0.1 to approximately 1. No nucleophilic substitution was observed at higher DSTos. At the chosen reaction conditions (60 °C, 48 h) residual tosyl moieties remained unchanged and little hydrolysis took place. The samples obtained were characterized by means of elemental analysis, FTIR and 13C CP/MAS NMR spectroscopy. 13C CP/MAS NMR spectroscopy was found to be an efficient tool for quantification of DSMA. Furthermore, the swelling behaviour in water was investigated and preliminary tests concerning the bilirubin adsorption capacity of MAC were carried out. 相似文献
84.
Regularity of Harmonic Functions in Cheeger-Type Sobolev Spaces 总被引:3,自引:0,他引:3
We give a geometric approach to the study of the regularity of harmonic functions in Cheeger-type Sobolev spaces, and prove the Hölder continuity of such functions. In the proof, we give a definition of an upper curvature bound of the unit sphere of a Banach space, which seems to be of independent interest. 相似文献
85.
In this note we show that many classes of global optimization problems can be treated most satisfactorily by classical optimization theory and conventional algorithms. We focus on the class of problems involving the minimization of the product of several convex functions on a convex set which was studied recently by Kunoet al. [3]. It is shown that these problems are typical composite concave programming problems and thus can be handled elegantly by c-programming [4]–[8] and its techniques. 相似文献
86.
汪巍 《数学的实践与认识》2004,34(3):103-109
首先引入了差分系统基于两种度量的极端稳定性概念 ,然后建立了一些关于差分系统 ( h0 ,h)极端稳定性 (极端一致稳定性 ,极端渐近稳定性 ,极端一致渐近稳定性 )的判定准则 .在所得到的定理中 ,对△ V的限制较弱 ,特别地 ,△V甚至可以恒为正 ,从而便于实际应用 . 相似文献
87.
We consider two classes of integrable nonlinear hyperbolic systems on Lie algebras. These systems generalize the principal chiral model. Each system is related to a pair of compatible Lie brackets and has a Lax representation, which is determined by the direct sum decomposition of the Lie algebra of Laurent series into the subalgebra of Taylor series and the complementary subalgebra corresponding to the pair. New examples of compatible Lie brackets are given. 相似文献
88.
Let P(z) be a polynomial of degree n with complex coefficients and consider the n–th order linear differential operator P(D). We show that the equation P(D)f = 0 has the Hyers–Ulam stability, if and only if the equation P(z) = 0 has no pure imaginary solution. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
89.
In the present work we consider the problem of interpolating scattered data using radial basis functions (RBF). In general, it is well known that this leads to a discrete linear inverse problem that needs to be regularized in order to provide a meaningful solution. The work focuses on a metric-regularization approach, based on a new class of RBF, called anisotropic RBF. The work provides theoretical justifications for the regularization approach and it considers a suitable proposal for the metric, supporting it by numerical examples. 相似文献
90.
P. Q. Khanh 《Journal of Optimization Theory and Applications》1995,87(2):359-378
We prove the Kuhn-Tucker sufficient optimality condition, the Wolfe duality, and a modified Mond-Weir duality for vector optimization problems involving various types of invex-convexlike functions. The class of such functins contains many known generalized convex functions. As applications, we demonstrate that, under invex-convexlikeness assumptions, the Pontryagin maximum principle is a sufficient optimality condition for cooperative differential games. The Wolfe duality is established for these games.The author is indebted to the referees and Professor W. Stadler for valuable remarks and comments, which have been used to revise considerably the paper. 相似文献