全文获取类型
收费全文 | 5482篇 |
免费 | 622篇 |
国内免费 | 393篇 |
专业分类
化学 | 367篇 |
晶体学 | 6篇 |
力学 | 186篇 |
综合类 | 175篇 |
数学 | 3342篇 |
物理学 | 2421篇 |
出版年
2024年 | 12篇 |
2023年 | 59篇 |
2022年 | 299篇 |
2021年 | 284篇 |
2020年 | 179篇 |
2019年 | 157篇 |
2018年 | 128篇 |
2017年 | 187篇 |
2016年 | 222篇 |
2015年 | 178篇 |
2014年 | 291篇 |
2013年 | 345篇 |
2012年 | 235篇 |
2011年 | 285篇 |
2010年 | 273篇 |
2009年 | 317篇 |
2008年 | 372篇 |
2007年 | 352篇 |
2006年 | 301篇 |
2005年 | 275篇 |
2004年 | 213篇 |
2003年 | 221篇 |
2002年 | 180篇 |
2001年 | 133篇 |
2000年 | 130篇 |
1999年 | 97篇 |
1998年 | 102篇 |
1997年 | 90篇 |
1996年 | 88篇 |
1995年 | 76篇 |
1994年 | 67篇 |
1993年 | 43篇 |
1992年 | 27篇 |
1991年 | 29篇 |
1990年 | 26篇 |
1989年 | 30篇 |
1988年 | 24篇 |
1987年 | 17篇 |
1986年 | 12篇 |
1985年 | 28篇 |
1984年 | 14篇 |
1983年 | 11篇 |
1982年 | 11篇 |
1981年 | 8篇 |
1980年 | 15篇 |
1979年 | 7篇 |
1978年 | 12篇 |
1977年 | 7篇 |
1976年 | 6篇 |
1972年 | 4篇 |
排序方式: 共有6497条查询结果,搜索用时 0 毫秒
1.
In this paper, we study generalized Douglas–Weyl(α, β)-metrics. Suppose that a regular(α, β)-metric F is not of Randers type. We prove that F is a generalized Douglas–Weyl metric with vanishing S-curvature if and only if it is a Berwald metric. Moreover, by ignoring the regularity, if F is not a Berwald metric, then we find a family of almost regular Finsler metrics which is not Douglas nor Weyl. As its application, we show that generalized Douglas–Weyl square metric or Matsumoto metric with isotropic mean Berwald curvature are Berwald metrics. 相似文献
2.
In 1976 S. Hawking claimed that “Because part of the information about the state of the system is lost down the hole, the final situation is represented by a density matrix rather than a pure quantum state”. 1 This was the starting point of the popular “black hole (BH) information paradox”. 相似文献
3.
We generalize Nagel’s formula for the Szegö kernel and use it to compute the Szegö kernel on a class of non-compact CR manifolds whose tangent space decomposes into one complex direction and several totally real directions. We also discuss the control metric on these manifolds and relate it to the size of the Szegö kernel. 相似文献
4.
Nonclassical light states are important for both conceptual and practical reasons: they are basic ingredients in testing and exploring quantum foundations, and are crucial resources in quantum technologies. Various useful criteria have been developed to detect nonclassicality in the literature, and several meaningful measures of nonclassicality have been introduced and measured experimentally. In this work, by use of a non-Hermitian generalization of the Wigner-Yanase-Dyson skew information and playing with operator ordering in evaluating average photon number, we develop a novel family of criteria for detecting nonclassicality of light based on Lieb's concavity, which is a deep and powerful result concerning interaction between quantum states and observables. We elucidate the information-theoretic as well as the physical meaning of the criteria, and illustrate their effectiveness in capturing and quantifying nonclassicality of various important light states. 相似文献
5.
采用DIS数字信息化系统,对不同浓度的蓝墨水溶液在激光光源照射下的透射平均照度及照度分布图像进行实验研究,得到了平均照度值随溶液浓度变化的规律。对不同颜色塑料膜片对白炽灯光源透过照度值及照度分布图像进行实验研究得到及其相关之规律。 相似文献
6.
设函数f(w)为凸区域D内的单叶解析函数,对于2≤n≤8和所有w∈D,本文得到估计式|f(n)(w)/f'(w)|的精确上界.这个结果推广了一些已知的结论. 相似文献
7.
On Quantum Team Games 总被引:2,自引:0,他引:2
E. Ahmed M. F. Elettreby A. S. Hegazi 《International Journal of Theoretical Physics》2006,45(5):880-886
Recently Liu and Simaan (2004) convex static multi-team classical games have been introduced. Here they are generalized to both nonconvex, dynamic and quantum games. Puu's incomplete information dynamical systems are modified and applied to Cournot team game. The replicator dynamics of the quantum prisoner's dilemma game is also studied. 相似文献
8.
Shunlong Luo 《Foundations of Physics》2002,32(11):1757-1772
We formulate an elementary statistical game which captures the essence of some fundamental quantum experiments such as photon polarization and spin measurement. We explore and compare the significance of the principle of maximum Shannon entropy and the principle of minimum Fisher information in solving such a game. The solution based on the principle of minimum Fisher information coincides with the solution based on an invariance principle, and provides an informational explanation of Malus' law for photon polarization. There is no solution based on the principle of maximum Shannon entropy. The result demonstrates the merits of Fisher information, and the demerits of Shannon entropy, in treating some fundamental quantum problems. It also provides a quantitative example in support of a general philosophy: Nature intends to hide Fisher information, while obeying some simple rules. 相似文献
9.
令Ω1与Ω2与C^n中的两个有界齐性域,假设φ:1Ω→Ω2是一个全纯映射。在本中,我们研究相应的复合算子Cφ:β(Ω2)→β(Ω1)的有界性和紧性,特别地,我们讨论取B^n和U^n的情形。 相似文献
10.
不完全信息群体决策专家权重的集结 总被引:8,自引:5,他引:3
本文对于属性权重信息和属性效用信息都不完全的群体多属性决策问题,通过构造属性值区间和运用系统聚类分析法,对群体决策中的专家进行分类,并确定每位专家的权重. 相似文献