全文获取类型
收费全文 | 5003篇 |
免费 | 261篇 |
国内免费 | 49篇 |
专业分类
化学 | 3501篇 |
晶体学 | 27篇 |
力学 | 144篇 |
综合类 | 1篇 |
数学 | 705篇 |
物理学 | 935篇 |
出版年
2023年 | 43篇 |
2022年 | 54篇 |
2021年 | 86篇 |
2020年 | 106篇 |
2019年 | 112篇 |
2018年 | 85篇 |
2017年 | 86篇 |
2016年 | 211篇 |
2015年 | 171篇 |
2014年 | 167篇 |
2013年 | 282篇 |
2012年 | 377篇 |
2011年 | 418篇 |
2010年 | 233篇 |
2009年 | 183篇 |
2008年 | 337篇 |
2007年 | 266篇 |
2006年 | 231篇 |
2005年 | 258篇 |
2004年 | 212篇 |
2003年 | 188篇 |
2002年 | 169篇 |
2001年 | 81篇 |
2000年 | 62篇 |
1999年 | 57篇 |
1998年 | 50篇 |
1997年 | 45篇 |
1996年 | 68篇 |
1995年 | 27篇 |
1994年 | 44篇 |
1993年 | 59篇 |
1992年 | 44篇 |
1991年 | 32篇 |
1990年 | 27篇 |
1989年 | 26篇 |
1988年 | 30篇 |
1987年 | 26篇 |
1986年 | 22篇 |
1985年 | 49篇 |
1984年 | 40篇 |
1983年 | 20篇 |
1982年 | 19篇 |
1981年 | 19篇 |
1980年 | 12篇 |
1979年 | 25篇 |
1978年 | 25篇 |
1977年 | 15篇 |
1975年 | 15篇 |
1974年 | 19篇 |
1973年 | 17篇 |
排序方式: 共有5313条查询结果,搜索用时 9 毫秒
341.
In this paper we study the asymptotic behavior of solutions of a first-order stochastic lattice dynamical system with a multiplicative noise.We do not assume any Lipschitz condition on the nonlinear term, just a continuity assumption together with growth and dissipative conditions, so that uniqueness of the Cauchy problem fails to be true.Using the theory of multi-valued random dynamical systems we prove the existence of a random compact global attractor. 相似文献
342.
We rigorously analyze the bifurcation of stationary so-called nonlinear Bloch waves (NLBs) from the spectrum in the Gross–Pitaevskii (GP) equation with a periodic potential, in arbitrary space dimensions. These are solutions which can be expressed as finite sums of quasiperiodic functions and which in a formal asymptotic expansion are obtained from solutions of the so-called algebraic coupled mode equations. Here we justify this expansion by proving the existence of NLBs and estimating the error of the formal asymptotics. The analysis is illustrated by numerical bifurcation diagrams, mostly in 2D. In addition, we illustrate some relations of NLBs to other classes of solutions of the GP equation, in particular to so-called out-of-gap solitons and truncated NLBs, and present some numerical experiments concerning the stability of these solutions. 相似文献
343.
Peter Hudák František Kardoš Tomáš Madaras Michaela Vrbjarová 《Czechoslovak Mathematical Journal》2016,66(4):1119-1128
We study improper interval edge colourings, defined by the requirement that the edge colours around each vertex form an integer interval. For the corresponding chromatic invariant (being the maximum number of colours in such a colouring), we present upper and lower bounds and discuss their qualities; also, we determine its values and estimates for graphs of various families, like wheels, prisms or complete graphs. The study of this parameter was inspired by the interval colouring, introduced by Asratian, Kamalian (1987). The difference is that we relax the requirement on the original colouring to be proper. 相似文献
344.
Christine Chou Steven O. Kimbrough 《Computational & Mathematical Organization Theory》2016,22(1):4-46
Organizational ambidexterity, defined as the pursuit of both exploitation and exploration, has become an important topic in the study of organizations, especially in innovation management theory. Previous literature has not focused on the strategic (game-theoretic) aspects of organizational ambidexterity or on its decision-making aspects. Little is known about how or even whether the decision to adopt ambidexterity is competitively advantageous in the presence of diverse strategies that competitors may adopt. This facet of the subject is inherently game-theoretic; the value of a decision by one firm depends in part on decisions made by other firms. This paper initiates systematic investigation of these strategic aspects, including the overall performance of available strategies. Specifically, this study examines questions of ambidexterity-related strategy performance in the context of new product development. The main contributions are (1) to introduce and make available to the research community an agent-based model and decision support system that captures many of the key aspects and tradeoffs, which have been identified in the literature, of the exploration–exploitation dilemma faced by firms in the new product development process, with a focus on organizations’ product investment decisions and (2) to report on results obtained from the model, calibrated with available data from the literature, augmented by new data collected from interviews with practitioners. 相似文献
345.
Tomás Caraballo Lassaad Mchiri 《Stochastics An International Journal of Probability and Stochastic Processes》2016,88(1):45-56
The method of Lyapunov functions is one of the most effective ones for the investigation of stability of dynamical systems, in particular, of stochastic differential systems. The main purpose of the paper is the analysis of the stability of stochastic differential equations (SDEs) by using Lyapunov functions when the origin is not necessarily an equilibrium point. The global uniform boundedness and the global practical uniform exponential stability of solutions of SDEs based on Lyapunov techniques are investigated. Furthermore, an example is given to illustrate the applicability of the main result. 相似文献
346.
Jiří M. Tomáš 《Czechoslovak Mathematical Journal》2006,56(4):1131-1145
347.
§1Introduction Asweknow,Backlundtransformation[1-3]isaverypowerfulwayforfindingnonline evolutionequations.Inrecentdecades,Painlevéanalysis[4]hasbecomeaverypopu methodtoobtainBacklundtransformation.Inreference[5],fordevelopingthetheory Painlevéanalysis,AndrewPickeringintroduceanewexpansionvariableZwhichsatisf thefollowingRicattiSystem:Zx=1-AZ-BZ2,Zt=-C+(AC+Cx)Z-(D-BC)Z2.(1.Astheapplicationofthenewexpansionvaraible,thepotentialfifth-orderMKd equation(PMKdV5)-vxt+(vxxxxx-10k2v2… 相似文献
348.
In this Note we first introduce the concept of pullback asymptotic compactness. Next, we establish a result ensuring the existence of a pullback attractor for a non-autonomous dynamical system under the general assumptions of pullback asymptotic compactness and the existence of a pullback absorbing family of sets. Finally, we prove the existence of a pullback attractor for a non-autonomous 2D Navier–Stokes model in an unbounded domain, a case in which the theory of uniform attractors does not work since the non-autonomous term is quite general. To cite this article: T. Caraballo et al., C. R. Acad. Sci. Paris, Ser. I 342 (2006). 相似文献
349.
Advances in Data Analysis and Classification - So far, most user studies dealing with comprehensibility of machine learning models have used questionnaires or surveys to acquire input from... 相似文献
350.
Tom Braden Anthony Licata Christopher Phan Nicholas Proudfoot Ben Webster 《Selecta Mathematica, New Series》2011,17(3):533-572
We show that the center of a flat graded deformation of a standard Koszul algebra A behaves in many ways like the torus-equivariant cohomology ring of an algebraic variety with finite fixed point set. In particular,
the center of A acts by characters on the deformed standard modules, providing a “localization map”. We construct a universal graded deformation
of A and show that the spectrum of its center is supported on a certain arrangement of hyperplanes which is orthogonal to the
arrangement coming from the algebra Koszul dual to A. This is an algebraic version of a duality discovered by Goresky and MacPherson between the equivariant cohomology rings
of partial flag varieties and Springer fibers; we recover and generalize their result by showing that the center of the universal
deformation for the ring governing a block of parabolic category O{\mathcal{O}} for
\mathfrakgln{\mathfrak{gl}_n} is isomorphic to the equivariant cohomology of a Spaltenstein variety. We also identify the center of the deformed version
of the “category O{\mathcal{O}}” of a hyperplane arrangement (defined by the authors in a previous paper) with the equivariant cohomology of a hypertoric
variety. 相似文献