全文获取类型
收费全文 | 425篇 |
免费 | 6篇 |
国内免费 | 3篇 |
专业分类
化学 | 136篇 |
晶体学 | 2篇 |
力学 | 9篇 |
数学 | 184篇 |
物理学 | 103篇 |
出版年
2022年 | 6篇 |
2021年 | 5篇 |
2019年 | 4篇 |
2018年 | 8篇 |
2017年 | 10篇 |
2016年 | 18篇 |
2015年 | 13篇 |
2014年 | 17篇 |
2013年 | 24篇 |
2012年 | 29篇 |
2011年 | 22篇 |
2010年 | 19篇 |
2009年 | 16篇 |
2008年 | 28篇 |
2007年 | 16篇 |
2006年 | 24篇 |
2005年 | 13篇 |
2004年 | 15篇 |
2003年 | 13篇 |
2002年 | 17篇 |
2001年 | 9篇 |
2000年 | 11篇 |
1999年 | 7篇 |
1998年 | 13篇 |
1997年 | 2篇 |
1996年 | 8篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1973年 | 2篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1937年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有434条查询结果,搜索用时 31 毫秒
151.
We consider the Tikhonov-like dynamics where A is a maximal monotone operator on a Hilbert space and the parameter function ε(t) tends to 0 as t→∞ with . When A is the subdifferential of a closed proper convex function f, we establish strong convergence of u(t) towards the least-norm minimizer of f. In the general case we prove strong convergence towards the least-norm point in A−1(0) provided that the function ε(t) has bounded variation, and provide a counterexample when this property fails. 相似文献
152.
Morelli MJ Allen RJ Tănase-Nicola S ten Wolde PR 《The Journal of chemical physics》2008,128(4):045105
In many stochastic simulations of biochemical reaction networks, it is desirable to "coarse grain" the reaction set, removing fast reactions while retaining the correct system dynamics. Various coarse-graining methods have been proposed, but it remains unclear which methods are reliable and which reactions can safely be eliminated. We address these issues for a model gene regulatory network that is particularly sensitive to dynamical fluctuations: a bistable genetic switch. We remove protein-DNA and/or protein-protein association-dissociation reactions from the reaction set using various coarse-graining strategies. We determine the effects on the steady-state probability distribution function and on the rate of fluctuation-driven switch flipping transitions. We find that protein-protein interactions may be safely eliminated from the reaction set, but protein-DNA interactions may not. We also find that it is important to use the chemical master equation rather than macroscopic rate equations to compute effective propensity functions for the coarse-grained reactions. 相似文献
153.
In this paper, for the univariate Bernstein–Kantorovich, Szász–Mirakjan–Kantorovich and Baskakov–Kantorovich operators written in terms of the Choquet integral with respect to a monotone and submodular set function, we obtain quantitative approximation estimates, uniform and pointwise in terms of the modulus of continuity. In addition, we show that for large classes of functions, the Kantorovich–Choquet type operators approximate better than their classical correspondents. Also, we construct new Szász–Mirakjan–Kantorovich–Choquet and Baskakov–Kantorovich–Choquet operators, which approximate uniformly f in each compact subinterval of \([0, +\infty )\) with the order \(\omega _{1}(f; \sqrt{\lambda _{n}})\), where \(\lambda _{n}\searrow 0\) arbitrary fast. 相似文献
154.
Marius Radulescu Sorin Radulescu 《Journal of Mathematical Analysis and Applications》2011,382(2):559-564
We discuss the problem of global invertibility of nonlinear maps defined on the finite dimensional Euclidean space via differential tests. We provide a generalization of the Fujisawa-Kuh global inversion theorem and introduce a generalized ratio condition which detects when the pre-image of a certain class of linear manifolds is non-empty and connected. In particular, we provide conditions that also detect global injectivity. 相似文献
155.
Iuliana Mihaela Jipa Anicuta Stoica Marta Stroescu Loredana-Mihaela Dobre Tanase Dobre Sorin Jinga Christu Tardei 《Chemical Papers》2012,66(2):138-143
Active packaging materials are the subject of research because their performance exceeds that of traditional packaging. From
this class, antimicrobial materials extend the shelf-life of products and reduce the risk of contamination by pathogens. In
this paper, new composite materials with antimicrobial properties are obtained by using polyvinyl alcohol and bacterial cellulose
powder. Potassium (2E,4E)-hexa-2,4-dienoate was used as the antimicrobial agent. The films thus obtained were characterised using Fourier-transform
infrared spectroscopy and scanning electron microscopy. Mass transfer phenomena concerning the release of potassium (2E,4E)-hexa-2,4-dienoate were investigated. The results indicated that the new biocomposite films could be used as antimicrobial
packaging materials. 相似文献
156.
We study CR functions with values in a complex Fréchet space X. We prove a vector valued analog to a result by Baouendi and Trèves (Ann Math 113:387–421, 1981), i.e. any X-valued CR function of Teodorescu class B 1 may be locally approximated by X-valued holomorphic functions on ${{\mathbb C}^n}$ . We show that any CR function ${u \in C^\omega (M, X)}$ on a real analytic CR hypersurface ${M \subset {\mathbb {C}}^n}$ admits a unique holomorphic extension ${f \in {\mathcal {O}}(\Omega, X)}$ to some open neighborhood ${\Omega \supset M}$ . 相似文献
157.
We consider a nonlinear antiplane problem which models the deformation of an elastic cylindrical body in frictional contact with a rigid foundation. The contact is modelled with Tresca’s law of dry friction in which the friction bound is slip dependent.The aim of this article is to study an optimal control problem which consists of leading the stress tensor as close as possible to a given target, by acting with a control on the boundary of the body. The existence of at least one optimal control is proved. Next we introduce a regularized problem, depending on a small parameter ρ, and we study the convergence of the optimal controls when ρ tends to zero. An optimality condition is delivered for the regularized problem. 相似文献
158.
Marius Rădulescu Sorin Rădulescu Constanţa Zoie Rădulescu 《European Journal of Operational Research》2009
We formulate and study a multiobjective programming approach for production processes which implements suitable constraints on pollutant emissions. We consider two alternative optimization problems: (a) minimum pollution risk; (b) maximum expected return. For each pollutant, we define three different contamination levels: (a) the desirable or the target pollution level, (b) the alarm (warning or critical) level and (c) the maximum admissible (acceptable) level, and introduce penalties proportional to the amounts of pollutants that exceed these levels. The objective function of the minimum pollution risk problem is not smooth since it contains positive parts of some affine functions, resulting in mathematical difficulties, which can be solved by formulating an alternative linear programming model, which makes use of additional variables and has the same solutions as the initial problem. We investigate various particular cases and analyze a numerical example for a textile plant. 相似文献
159.
160.
S. V. Molodtsov T. Siemiarczuk A. N. Sissakian A. S. Sorin G. M. Zinovjev 《The European Physical Journal C - Particles and Fields》2009,61(1):61-68
The origin of the lightest scalar mesons is studied in the framework of the instanton liquid model of the QCD vacuum. The
impact of phonon-like vacuum excitations on the σ-meson features is qualitatively analyzed. In particular, it is noticed that the changes produced in the scalar sector may
unexpectedly become quite considerable in spite of insignificant values of corrections to the dynamical quark masses and then
the medley of σ-meson and those excitations may reveal itself as broad resonance states of different masses. 相似文献