全文获取类型
收费全文 | 7754篇 |
免费 | 1319篇 |
国内免费 | 619篇 |
专业分类
化学 | 1481篇 |
晶体学 | 19篇 |
力学 | 809篇 |
综合类 | 94篇 |
数学 | 1395篇 |
物理学 | 5894篇 |
出版年
2024年 | 9篇 |
2023年 | 44篇 |
2022年 | 138篇 |
2021年 | 138篇 |
2020年 | 162篇 |
2019年 | 134篇 |
2018年 | 131篇 |
2017年 | 292篇 |
2016年 | 334篇 |
2015年 | 293篇 |
2014年 | 461篇 |
2013年 | 542篇 |
2012年 | 511篇 |
2011年 | 529篇 |
2010年 | 403篇 |
2009年 | 481篇 |
2008年 | 556篇 |
2007年 | 561篇 |
2006年 | 497篇 |
2005年 | 411篇 |
2004年 | 384篇 |
2003年 | 367篇 |
2002年 | 297篇 |
2001年 | 302篇 |
2000年 | 279篇 |
1999年 | 207篇 |
1998年 | 190篇 |
1997年 | 181篇 |
1996年 | 138篇 |
1995年 | 113篇 |
1994年 | 90篇 |
1993年 | 82篇 |
1992年 | 57篇 |
1991年 | 64篇 |
1990年 | 53篇 |
1989年 | 37篇 |
1988年 | 35篇 |
1987年 | 36篇 |
1986年 | 18篇 |
1985年 | 31篇 |
1984年 | 27篇 |
1983年 | 17篇 |
1982年 | 20篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1957年 | 3篇 |
排序方式: 共有9692条查询结果,搜索用时 31 毫秒
71.
We propose general variational inclusion problems which are slightly different from corresponding problems considered in several recent papers in the literature and show that they are advantageous. Sufficient conditions for the solution existence are established. As applications we derive consequences for several special cases of variational inclusion problems, quasioptimization problems, equilibrium problems and implicit variational inequalities and show that they improve the results of some recent existing papers. 相似文献
72.
73.
Let Top
0
be the category of topological T
0-spaces, QU
0
the category of quasi-uniform T
0-spaces, T : QU
0
→ Top
0
the usual forgetful functor and K : QU
0
→ QU
0
the bicompletion reflector with unit k : 1 → K. Any T-section F : Top
0
→ QU
0
is called K-true if KF = FTKF, and upper (lower)
K-true if KF is finer (coarser) than FTKF. The literature considers important T-sections F that enjoy all three, or just one, or none of these properties. It is known that T(K,k)F is well-pointed if and only if F is upper K-true. We prove the surprising fact that T(K,k)F is the reflection to Fix(TkF) whenever it is idempotent. We also prove a new characterization of upper K-trueness. We construct examples to set apart some natural cases. In particular we present an upper K-true F for which T(K,k)F is not idempotent, and a K-true F for which the coarsest associated T-preserving coreflector in QU
0
is not stable under K.
We dedicate this paper to the memory of Sérgio de Ornelas Salbany (1941–2005). 相似文献
74.
基于爆轰波原理声源定位方法初探 总被引:5,自引:0,他引:5
基于弹丸发射时所发出的爆轰波,利用传感器接收时差信息,从而确定声源位置。本文建立了该声源定位反问题的物理和数学模型,并依据该模型寻求适当的数值解法,最后针对延拓-广义逆法声源定位问题进行了演算和简要分析。 相似文献
75.
Michael Devereux 《Foundations of Physics Letters》2003,16(1):41-55
Using an isolated measurement process, we calculate the effect measurement has on entropy for the multi-cylinder Szilard engine. We find that the system of cylinders possesses an entropy associated with cylinder total energy states, and that it records information transferred at measurement. Contrary to other's results, we find that the apparatus loses entropy due to measurement. The Second Law of Thermodynamics may be preserved if Maxwell's demon gains entropy moving the engine partition. 相似文献
76.
In this paper we deal with nonlinear second-order boundary value problems with impulses. The impulsive functions depend implicitly on the different considered variables and the boundary value conditions are nonlinear. In both cases functional dependence on the solution is allowed. The existence results follow from the existence of a pair of well-ordered lower and upper solutions. 相似文献
77.
Quantum Key Distribution Using Four-Qubit W State 总被引:3,自引:0,他引:3
CAO Hai-Jing SONG He-Shan 《理论物理通讯》2006,46(1):65-68
A new theoretical quantum key distribution scheme based on entanglement swapping is proposed, where four-qubit symmetric W state functions as quantum channel. It is shown that two legitimate users can secretly share a series of key bits by using Bell-state measurements and classical communication. 相似文献
78.
79.
80.