全文获取类型
收费全文 | 5943篇 |
免费 | 1017篇 |
国内免费 | 845篇 |
专业分类
化学 | 4435篇 |
晶体学 | 69篇 |
力学 | 481篇 |
综合类 | 71篇 |
数学 | 684篇 |
物理学 | 2065篇 |
出版年
2024年 | 26篇 |
2023年 | 133篇 |
2022年 | 230篇 |
2021年 | 246篇 |
2020年 | 298篇 |
2019年 | 258篇 |
2018年 | 219篇 |
2017年 | 240篇 |
2016年 | 297篇 |
2015年 | 329篇 |
2014年 | 382篇 |
2013年 | 455篇 |
2012年 | 540篇 |
2011年 | 582篇 |
2010年 | 382篇 |
2009年 | 391篇 |
2008年 | 353篇 |
2007年 | 292篇 |
2006年 | 272篇 |
2005年 | 248篇 |
2004年 | 218篇 |
2003年 | 173篇 |
2002年 | 183篇 |
2001年 | 189篇 |
2000年 | 113篇 |
1999年 | 135篇 |
1998年 | 102篇 |
1997年 | 74篇 |
1996年 | 93篇 |
1995年 | 58篇 |
1994年 | 71篇 |
1993年 | 46篇 |
1992年 | 33篇 |
1991年 | 32篇 |
1990年 | 23篇 |
1989年 | 17篇 |
1988年 | 16篇 |
1987年 | 9篇 |
1986年 | 15篇 |
1985年 | 7篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1975年 | 1篇 |
排序方式: 共有7805条查询结果,搜索用时 15 毫秒
971.
Additive-free controllable fabrication of bismuth vanadates and their photocatalytic activity toward dye degradation 总被引:1,自引:0,他引:1
Bismuth vanadates (BiVO4) with various crystal structures (tetragonal scheelite, monoclinic scheelite, and tetragonal zircon) and morphologies (sphere-, nanosheet-, dendrite-, and flower-like) were controllably fabricated by using a mild additive-free hydrothermal treatment process under the different preparation conditions. The crystal structures, morphologies, and photophysical properties of the products were well-characterized. Subsequently, their UV- as well as visible-light photocatalytic performance was evaluated via dyes rhodamine B (RB) and methylene blue (MB) degradation. Special attention was paid to evaluate the correlation of the reactivity with crystal structure, morphology, and electronic structure of as-prepared BiVO4 samples. 相似文献
972.
973.
Complete Space-like λ-surfaces in the Minkowski Space R1^3 with the Second Fundamental Form of Constant Length 下载免费PDF全文
In this paper we study the complete space-like λ-surfaces in the three dimensional Minkowski space R1^3.As the result,we obtain a complete classification theorem for all the complete space-like λ-surfaces x:M^2→R1^3 with the second fundamental form of constant length.This is a natural extension to the λ-surfaces in R1^3 of a recent interesting classification theorem by Cheng and Wei forλ-surfaces in the Euclidean space R^3. 相似文献
974.
In this paper, we introduce the class of extended Hamilton operators and study various properties of this class. We examine the decomposability of extended Hamilton operators. In addition,we prove that an extended Hamilton operator with property(δ) is subscalar. Finally, we consider Weyl type theorems of this class. 相似文献
975.
The alternating direction method of multipliers (ADMM) has recently received a lot of attention especially due to its capability to harness the power of the new parallel and distributed computing environments. However, ADMM could be notoriously slow especially if the penalty parameter, assigned to the augmented term in the objective function, is not properly chosen. This paper aims to accelerate ADMM by integrating that with the Barzilai–Borwein gradient method and an acceleration technique known as line search. Line search accelerates an iterative method by performing a one-dimensional search along the line segment connecting two successive iterations. We pay a special attention to the large-scale nonnegative least squares problems, and our experiments using real datasets indicate that the integration not only accelerate ADMM but also robustifies that against the penalty parameter. 相似文献
976.
In this paper, we investigate the error estimates for the solutions of optimal control problems by mixed finite element methods. The state and costate are approximated by Raviart-Thomas mixed finite element spaces of order k and the control is approximated by piecewise polynomials of order k. Under the special constraint set, we will show that the control variable can be smooth in the whole domain. We derive error estimates of optimal order both for the state variables and the control variable. 相似文献
977.
In this paper, we study the closeness of strongly (∞)-hopfian properties under some constructions such as the ring of Morita context, direct products, triangular matrix, fraction ring etc. Also, we prove that if M[X] is strongly hopfian (resp. strongly co-hopfian) in R[X]-Mod, then M is strongly hopfian (resp. strongly co-hopfian) in R-Mod. 相似文献
978.
One-dimensional local Dirichlet spaces associated with linear diffusions are studied. The first result is to give a representation for any 1-dim local, irreducible and regular Diriehlet space. The second result is a necessary and sufficient condition for a Diriehlet space to be regular subspace of another Dirichlet space. 相似文献
979.
Yan-Ling Li Jingsong Huang Xing Xiao 《International Journal of Theoretical Physics》2013,52(11):3797-3807
We show that entanglement between three two-level atoms can be generated if the three atoms interact with a common structured reservoir, but do not interact directly with each other. Comparing with the results in Markovian case, we find that much higher values of bipartite and tripartite entanglement can be obtained for an initially factorized state of the tripartite system. The maximal value of entanglement depends on the detuning and the strength of relative coupling between the atoms and the reservoir. 相似文献
980.