全文获取类型
收费全文 | 4933篇 |
免费 | 166篇 |
国内免费 | 16篇 |
专业分类
化学 | 2971篇 |
晶体学 | 32篇 |
力学 | 134篇 |
数学 | 621篇 |
物理学 | 1357篇 |
出版年
2022年 | 25篇 |
2021年 | 69篇 |
2020年 | 81篇 |
2019年 | 65篇 |
2018年 | 38篇 |
2017年 | 45篇 |
2016年 | 104篇 |
2015年 | 88篇 |
2014年 | 120篇 |
2013年 | 177篇 |
2012年 | 252篇 |
2011年 | 317篇 |
2010年 | 157篇 |
2009年 | 139篇 |
2008年 | 271篇 |
2007年 | 248篇 |
2006年 | 266篇 |
2005年 | 253篇 |
2004年 | 198篇 |
2003年 | 147篇 |
2002年 | 129篇 |
2001年 | 103篇 |
2000年 | 67篇 |
1999年 | 48篇 |
1998年 | 43篇 |
1997年 | 67篇 |
1996年 | 93篇 |
1995年 | 71篇 |
1994年 | 65篇 |
1993年 | 89篇 |
1992年 | 53篇 |
1991年 | 30篇 |
1990年 | 36篇 |
1989年 | 42篇 |
1988年 | 38篇 |
1987年 | 34篇 |
1986年 | 40篇 |
1985年 | 26篇 |
1984年 | 38篇 |
1983年 | 30篇 |
1982年 | 31篇 |
1981年 | 24篇 |
1980年 | 30篇 |
1978年 | 29篇 |
1975年 | 33篇 |
1974年 | 23篇 |
1968年 | 49篇 |
1967年 | 117篇 |
1966年 | 110篇 |
1965年 | 71篇 |
排序方式: 共有5115条查询结果,搜索用时 15 毫秒
11.
The projective method for solving linear matrix inequalities 总被引:2,自引:0,他引:2
Numerous problems in control and systems theory can be formulated in terms of linear matrix inequalities (LMI). Since solving
an LMI amounts to a convex optimization problem, such formulations are known to be numerically tractable. However, the interest
in LMI-based design techniques has really surged with the introduction of efficient interior-point methods for solving LMIs
with a polynomial-time complexity. This paper describes one particular method called the Projective Method. Simple geometrical
arguments are used to clarify the strategy and convergence mechanism of the Projective algorithm. A complexity analysis is
provided, and applications to two generic LMI problems (feasibility and linear objective minimization) are discussed. 相似文献
12.
13.
Pascal Cherrier 《Bulletin des Sciences Mathématiques》2007,131(4):375-396
We study a parabolic version of a system of Von Karman type on a compact Kähler manifold of arbitrary dimension. We provide local in time regular solutions, which can be extended to global bounded ones if the data of the problem are small. 相似文献
14.
15.
We study perturbations of the Erdös–Renyi model for which the statistical weight of a graph depends on the abundance of certain geometrical patterns. Using the formal correspondance with an exactly solvable effective model, we show the existence of a percolation transition in the thermodynamical limit and derive perturbatively the expression of the threshold. The free energy and the moments of the degree distribution are also computed perturbatively in that limit and the percolation criterion is compared with the Molloy–Reed criterion. 相似文献
16.
We consider optimal control problems for systems described by stochastic differential equations with delay. We state conditions
for certain classes of such systems under which the stochastic control problems become finite-dimensional. These conditions
are illustrated with three applications. First, we solve some linear quadratic problems with delay. Then we find the optimal
consumption rate in a financial market with delay. Finally, we solve explicitly a deterministic fluid problem with delay which
arises from admission control in ATM communication networks. 相似文献
17.
18.
Serge Palacin Christophe Bureau Julienne Charlier Guy Deniau Brigitte Mouanda Pascal Viel 《Chemphyschem》2004,5(10):1468-1481
Electrografting is a powerful and versatile technique for modifying and decorating conducting surfaces with organic matter. Mainly based on the electro-induced polymerization of dissolved electro-active monomers on metallic or semiconducting surfaces, it finds applications in various fields including biocompatibility, protection against corrosion, lubrication, soldering, functionalization, adhesion, and template chemistry. Starting from experimental observations, this Review highlights the mechanism of the formation of covalent metal-carbon bonds by electro-induced processes, together with major applications such as derivatization of conducting surfaces with biomolecules that can be used in biosensing, lubrication of low-level electrical contacts, reversible trapping of ionic waste on reactive electrografted surfaces as an alternative to ion-exchange resins, and localized modification of conducting surfaces, a one-step process providing submicrometer grafted areas and which is used in microelectronics. 相似文献
19.
We characterize the sequences of orthogonal polynomials on the unit circle whose derivatives are also orthogonal polynomials on the unit circle. Some relations for the sequences of derivatives of orthogonal polynomials are provided. Finally, we pose some problems about orthogonality-preserving maps and differential equations for orthogonal polynomials on the unit circle. 相似文献
20.
An efficient preconditioner is developed for solving the Helmholtz problem in both high and low frequency (wavenumber) regimes. The preconditioner is based on hierarchical unknowns on nested grids, known as incremental unknowns (IU). The motivation for the IU preconditioner is provided by an eigenvalue analysis of a simplified Helmholtz problem. The performance of our preconditioner is tested on the iterative solution of two‐dimensional electromagnetic scattering problems. When compared with other well‐known methods, our technique is shown to often provide a better numerical efficacy and, most importantly, to be more robust. Moreover, for the best performance, the number of IU levels used in the preconditioner should be designed for the coarsest grid to have roughly two points per linear wavelength. This result is consistent with the conventional sampling criteria for wave phenomena in contrast with existing IU applications for solving the Laplace/Poisson problem, where the coarsest grid comprises just one interior point. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007 相似文献