全文获取类型
收费全文 | 26196篇 |
免费 | 1941篇 |
国内免费 | 1289篇 |
专业分类
化学 | 725篇 |
晶体学 | 41篇 |
力学 | 4461篇 |
综合类 | 248篇 |
数学 | 20205篇 |
物理学 | 3746篇 |
出版年
2024年 | 44篇 |
2023年 | 265篇 |
2022年 | 320篇 |
2021年 | 370篇 |
2020年 | 665篇 |
2019年 | 652篇 |
2018年 | 681篇 |
2017年 | 681篇 |
2016年 | 721篇 |
2015年 | 601篇 |
2014年 | 1153篇 |
2013年 | 2403篇 |
2012年 | 1196篇 |
2011年 | 1458篇 |
2010年 | 1253篇 |
2009年 | 1653篇 |
2008年 | 1723篇 |
2007年 | 1717篇 |
2006年 | 1488篇 |
2005年 | 1164篇 |
2004年 | 1080篇 |
2003年 | 1063篇 |
2002年 | 951篇 |
2001年 | 740篇 |
2000年 | 743篇 |
1999年 | 647篇 |
1998年 | 620篇 |
1997年 | 543篇 |
1996年 | 425篇 |
1995年 | 336篇 |
1994年 | 277篇 |
1993年 | 245篇 |
1992年 | 236篇 |
1991年 | 208篇 |
1990年 | 172篇 |
1989年 | 92篇 |
1988年 | 82篇 |
1987年 | 77篇 |
1986年 | 76篇 |
1985年 | 94篇 |
1984年 | 110篇 |
1983年 | 59篇 |
1982年 | 77篇 |
1981年 | 58篇 |
1980年 | 42篇 |
1979年 | 42篇 |
1978年 | 32篇 |
1977年 | 30篇 |
1976年 | 22篇 |
1973年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Xian Xu 《Journal of Mathematical Analysis and Applications》2004,291(2):673-689
In this paper, some multiplicity results for positive solutions of some singular semi-positone three-point boundary value problem be obtained by using the fixed point index method. 相似文献
92.
Zhimin He 《Journal of Mathematical Analysis and Applications》2004,296(1):97-109
In this paper, by means of a new twin fixed-point theorem in a cone, the existence of at least two positive solutions of m-point boundary value problem for second order dynamic equations on time scales is considered. 相似文献
93.
We consider the Maxwell-Cattaneo system of equations for generalized heat conduction where the temperature and heat flux satisfy a nonstandard auxiliary condition which prescribes a combination of their values initially and at a later time. We obtain L2 bounds for the temperature and heat flux by means of Lagrange identities. These bounds extend the range of validity for the parameter in the nonstandard condition under a constraint on the coefficients in the differential equations. 相似文献
94.
Nguyen Minh Chuong Bui Kien Cuong 《Proceedings of the American Mathematical Society》2004,132(12):3589-3597
A class of Cauchy problems for interesting complicated periodic pseudodifferential equations is considered. By the Galerkin-wavelet method and with weak solutions one can find sufficient conditions to establish convergence estimates of weak Galerkin-wavelet solutions to a Cauchy problem for this class of equations.
95.
In this work, the NP-hard maximum clique problem on graphs is considered. Starting from basic greedy heuristics, modifications and improvements are proposed and combined in a two-phase heuristic procedure. In the first phase an improved greedy procedure is applied starting from each node of the graph; on the basis of the results of this phase a reduced subset of nodes is selected and an adaptive greedy algorithm is repeatedly started to build cliques around such nodes. In each restart the selection of nodes is biased by the maximal clique generated in the previous execution. Computational results are reported on the DIMACS benchmarks suite. Remarkably, the two-phase procedure successfully solves the difficult Brockington-Culberson instances, and is generally competitive with state-of-the-art much more complex heuristics. 相似文献
96.
97.
In this paper, we study the linearization of the Cauchy problem and the mixed problem for the system of Grad--Hermite moments in nonequilibrium thermodynamics in the neighborhood of the equilibrium state. Stability conditions for solutions of the Cauchy problem are proved as a generalization of the classical Hermite--Biller theorem on stable polynomials. For the mixed problem, we prove an analog of the Vishik--Lyusternik theorem on small singular perturbations of general elliptic problems. The last observation allows us to introduce the Shapiro--Lopatinskii condition, which implies the well-posedness of the mixed problem. 相似文献
98.
The periodic precipitation pattern formation in gelatinous media is interpreted as a moving boundary problem. The time law,
spacing law and width law are revisited on the basis of the new scenario. The explicit dependence of the geometric structure
on the initial concentrations of the reactants is derived. Matalon—Packter law, which relates the spacing coefficient with
the initial concentrations is reformulated removing many ambiguities and impractical parameters. Experimental results are
discussed to establish the significance of moving boundary concept in the diffusion controlled pattern forming systems 相似文献
99.
We show that for a random choice of the parameters, the subset sum pseudorandom number generator produces a sequence of uniformly and independently distributed pseudorandom numbers. The result can be useful for both cryptographic and quasi-Monte Carlo applications and relies on bounds of exponential sums.
100.
In this paper we give necessary and sufficient conditions for the existence of a C>
0-semigroup in L
1(I) (I real interval) generated by a second-order differential operator when suitable boundary conditions at the endpoints are imposed. 相似文献