全文获取类型
收费全文 | 642篇 |
免费 | 15篇 |
国内免费 | 18篇 |
专业分类
化学 | 285篇 |
晶体学 | 4篇 |
力学 | 4篇 |
数学 | 310篇 |
物理学 | 72篇 |
出版年
2023年 | 3篇 |
2022年 | 15篇 |
2021年 | 20篇 |
2020年 | 12篇 |
2019年 | 18篇 |
2018年 | 10篇 |
2017年 | 10篇 |
2016年 | 20篇 |
2015年 | 21篇 |
2014年 | 23篇 |
2013年 | 48篇 |
2012年 | 50篇 |
2011年 | 48篇 |
2010年 | 37篇 |
2009年 | 34篇 |
2008年 | 46篇 |
2007年 | 40篇 |
2006年 | 37篇 |
2005年 | 23篇 |
2004年 | 25篇 |
2003年 | 23篇 |
2002年 | 13篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 7篇 |
1995年 | 9篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1971年 | 1篇 |
排序方式: 共有675条查询结果,搜索用时 0 毫秒
631.
Alexandru Aleman Alfonso Montes-Rodríguez Andreea Sarafoleanu 《Constructive Approximation》2012,36(3):353-374
For each noninteger complex number ??, the Hilbert matrix $$H_\lambda= \biggl( \frac{1}{n+m+\lambda} \biggr)_{n,m\geq0}$$ defines a bounded linear operator on the Hardy spaces $\mathcal{H}^{p}$ , 1<p<??, and on the Korenblum spaces $\mathcal{A}^{-\tau}$ , ??>0. In this work, we determine the point spectrum with multiplicities of the Hilbert matrix acting on these spaces. This extends to complex ?? results by Hill and Rosenblum for real ??. We also provide a closed formula for the eigenfunctions. They are in fact closely related to the associated Legendre functions of the first kind. The results will be achieved through the analysis of certain differential operators in the commutator of the Hilbert matrix. 相似文献
632.
Alexandru Buium 《Journal of Number Theory》2006,119(2):297-306
The arithmetic Kodaira-Spencer class of the universal elliptic curve was introduced in [A. Buium, Differential modular forms, J. Reine Angew. Math. 520 (2000) 95-167]; its reduction mod p was explicitly computed by Hurlburt [C. Hurlburt, Isogeny covariant differential modular forms modulo p, Compos. Math. 128 (1) (2001) 17-34]. In this paper the complicated expression of Hurlburt is shown to be the unique solution of a simple partial differential equation subject to a certain initial condition and weight condition. 相似文献
633.
Brigitte E. Breckner Alexandru Horváth Csaba Varga 《Nonlinear Analysis: Theory, Methods & Applications》2009
We prove the existence of multiple solutions of certain systems of hemivariational inequalities, using a recent minimax result of B. Ricceri. We apply both our main theorem and the principle of symmetric criticality to obtain multiple solutions of systems of hemivariational inequalities defined on certain Sobolev spaces. 相似文献
634.
We estimate the norm of the almost Mathieu operator , regarded as an element in the rotation C*-algebra . In the process, we prove for every λ∈R and the inequality
635.
We study derivations and differential forms on the arithmetic jet spaces of smooth schemes, relative to several primes. As
applications, we give a new interpretation of arithmetic Laplacians, and we discuss the de Rham cohomology of some specific
arithmetic jet spaces, especially arithmetic jet spaces of linear tori, elliptic curves, and Kummer surfaces. 相似文献
636.
The Coanda effect that is the tendency of a fluid jet to stay attached to an adjacent curved surface that is very well shaped has been employed to improve the performance of various devices. The main objective of this paper is to investigate ways of keeping the flow attached to a larger length of a Coanda surface. There are considered two possibilities: one passive, which uses a slot that connects the low pressure and high pressure points on the Coanda surface and an active one, based on the principle of synthetic jet, created through an orifice located near the point of detachment of the jet. Reynolds averaged Navier-Stokes simulations (RANS) with shear stress transport k-ω (SST model) of Menter have been used to compute the two-dimensional turbulent wall jet. The numerical results are presented for the two methods considered. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
637.
Alexandru Emil Stanculescu 《Applied Categorical Structures》2013,21(6):781-800
The category of small 2-categories has two monoidal structures due to John Gray: one biclosed and one closed. We propose a formalisation of the construction of the right internal and internal homs of these monoidal structures. 相似文献
638.
We present a complete, decidable logic for reasoning about a notion of completely trustworthy (“conclusive”) evidence and its relations to justifiable (implicit) belief and knowledge, as well as to their explicit justifications. This logic makes use of a number of evidence-related notions such as availability, admissibility, and “goodness” of a piece of evidence, and is based on an innovative modification of the Fitting semantics for Artemov?s Justification Logic designed to preempt Gettier-type counterexamples. We combine this with ideas from belief revision and awareness logics to provide an account for explicitly justified (defeasible) knowledge based on conclusive evidence that addresses the problem of (logical) omniscience. 相似文献
639.
Alexandru Kristály Dumitru Motreanu 《Numerical Functional Analysis & Optimization》2013,34(11-12):1309-1326
This paper deals with the problem ? Δ p u + α(x)|u| p?2 u = β(x)f(|u|) in Ω, subjected to the zero Neumann boundary condition, where p > 1, Ω ? ? N is bounded with smooth boundary, α, β ? L ∞(Ω), essinfΩβ > 0, and f:[0,+ ∞) → ? is a not necessarily continuous nonlinearity that oscillates either at the origin or at the infinity. By using nonsmooth variational methods, we establish in both cases the existence of infinitely many distinct non-negative solutions of the Neumann problem. In our framework, α:Ω → ? may be a sign-changing or even a nonpositive potential, which is not permitted usually in earlier works. 相似文献
640.
Evolutionary Algorithms, also known as Genetic Algorithms in a former terminology, are probabilistic algorithms for optimization, which mimic operators from natural selection and genetics. The paper analyses the convergence of the heuristic associated to a special type of Genetic Algorithm, namely the Steady State Genetic Algorithm (SSGA), considered as a discrete-time dynamical system non-generational model. Inspired by the Markov chain results in finite Evolutionary Algorithms, conditions are given under which the SSGA heuristic converges to the population consisting of copies of the best chromosome. 相似文献