全文获取类型
收费全文 | 8489篇 |
免费 | 924篇 |
国内免费 | 778篇 |
专业分类
化学 | 1229篇 |
晶体学 | 92篇 |
力学 | 731篇 |
综合类 | 190篇 |
数学 | 6237篇 |
物理学 | 1712篇 |
出版年
2024年 | 10篇 |
2023年 | 77篇 |
2022年 | 115篇 |
2021年 | 139篇 |
2020年 | 210篇 |
2019年 | 250篇 |
2018年 | 232篇 |
2017年 | 279篇 |
2016年 | 321篇 |
2015年 | 237篇 |
2014年 | 412篇 |
2013年 | 727篇 |
2012年 | 410篇 |
2011年 | 519篇 |
2010年 | 446篇 |
2009年 | 508篇 |
2008年 | 530篇 |
2007年 | 541篇 |
2006年 | 466篇 |
2005年 | 441篇 |
2004年 | 381篇 |
2003年 | 336篇 |
2002年 | 380篇 |
2001年 | 322篇 |
2000年 | 315篇 |
1999年 | 277篇 |
1998年 | 225篇 |
1997年 | 221篇 |
1996年 | 140篇 |
1995年 | 107篇 |
1994年 | 84篇 |
1993年 | 62篇 |
1992年 | 53篇 |
1991年 | 54篇 |
1990年 | 26篇 |
1989年 | 33篇 |
1988年 | 38篇 |
1987年 | 28篇 |
1986年 | 20篇 |
1985年 | 38篇 |
1984年 | 34篇 |
1983年 | 18篇 |
1982年 | 24篇 |
1981年 | 18篇 |
1980年 | 16篇 |
1979年 | 21篇 |
1978年 | 12篇 |
1977年 | 6篇 |
1976年 | 10篇 |
1959年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
11.
12.
Taekyun Kim 《Journal of Mathematical Analysis and Applications》2002,273(1):236-242
The purpose of this paper is to give a proof of Kummer type congruence for the q-Bernoulli numbers of higher order, which is an answer to a part of the problem in a previous publication (see Indian J. Pure Appl. Math. 32 (2001) 1565-1570). 相似文献
13.
14.
P. E. Cladis 《Journal of statistical physics》1991,62(5-6):899-925
We first discuss nonlinear aspects of phase transition theory applied to a particular liquid crystal phase transition. A simple derivation is given to show how two coupled Goldstone modes (one appearing as gauge fluctuations of the ordered phase) can force a phase transition, against all expectations, to take place discontinuously (theory of Halperin, Lubensky, and Ma)-but the discontinuity may be immeasurably small. Then, we describe a new dynamical test of phase transition order, developed by Cladiset al., that turns out to be more sensitive than x-ray diffraction and adiabatic calorimetry. Quantitative data found by this new method are in excellent agreement with the measurements of adiabatic calorimetry and x-ray diffraction as well as expectations implicit in the predictions of HLM.This is the text of an after-banquet talk given at the CNLS Workshop on the Dynamics of Concentrated Systems. 相似文献
15.
Harel and Puri (1989, J. Multivariate Anal. 29) studied the asymptotic behavior of the U-statistic and the one-sample rank order statistic for nonstationary absolutely regular processes. In this note, we present some applications of these results for Markov processes as well as ARMA processes. 相似文献
16.
本文给出Riccati方程及另外一类具有代表性微分方程的亚纯解(n,1)级的上界估计,在一定条件下确立了文[2]中的猜测的正确性。 相似文献
17.
In this paper we consider an initial boundary value problem for a reaction-diffusion equation under nonlinear and nonlocal Robin type boundary condition. Assuming the existence of an ordered pair of upper and lower solutions we establish a generalized quasilinearization method for the problem under consideration whose characteristic feature consists in the construction of monotone sequences converging to the unique solution within the interval of upper and lower solutions, and whose convergence rate is quadratic. Thus this method provides an efficient iteration technique that produces not only improved approximations due to the monotonicity of its iterates, but yields also a measure of the convergence rate. 相似文献
18.
Dalila B. M. M. Fontes Eleni Hadjiconstantinou Nicos Christofides 《Journal of Global Optimization》2006,34(1):97-125
In this paper we obtain Lower Bounds (LBs) to concave cost network flow problems. The LBs are derived from state space relaxations
of a dynamic programming formulation, which involve the use of non-injective mapping functions guaranteing a reduction on
the cardinality of the state space. The general state space relaxation procedure is extended to address problems involving
transitions that go across several stages, as is the case of network flow problems. Applications for these LBs include: estimation
of the quality of heuristic solutions; local search methods that use information of the LB solution structure to find initial
solutions to restart the search (Fontes et al., 2003, Networks, 41, 221–228); and branch-and-bound (BB) methods having as
a bounding procedure a modified version of the LB algorithm developed here, (see Fontes et al., 2005a). These LBs are iteratively
improved by penalizing, in a Lagrangian fashion, customers not exactly satisfied or by performing state space modifications.
Both the penalties and the state space are updated by using the subgradient method. Additional constraints are developed to
improve further the LBs by reducing the searchable space. The computational results provided show that very good bounds can
be obtained for concave cost network flow problems, particularly for fixed-charge problems. 相似文献
19.
20.
We establish a relation between stable distributions in probability theory and the fractional integral. Moreover, it turns out that the parameter of the stable distribution coincides with the exponent of the fractional integral. It follows from an analysis of the obtained results that equations with the fractional time derivative describe the evolution of some physical system whose time degree of freedom becomes stochastic, i.e., presents a sum of random time intervals subject to a stable probability distribution. We discuss relations between the fractal Cantor set (Cantor strips) and the fractional integral. We show that the possibility to use this relation as an approximation of the fractional integral is rather limited. 相似文献