全文获取类型
收费全文 | 4854篇 |
免费 | 512篇 |
国内免费 | 237篇 |
专业分类
化学 | 413篇 |
晶体学 | 6篇 |
力学 | 170篇 |
综合类 | 163篇 |
数学 | 2573篇 |
物理学 | 2278篇 |
出版年
2024年 | 6篇 |
2023年 | 41篇 |
2022年 | 196篇 |
2021年 | 279篇 |
2020年 | 159篇 |
2019年 | 127篇 |
2018年 | 102篇 |
2017年 | 155篇 |
2016年 | 194篇 |
2015年 | 126篇 |
2014年 | 273篇 |
2013年 | 320篇 |
2012年 | 189篇 |
2011年 | 246篇 |
2010年 | 254篇 |
2009年 | 301篇 |
2008年 | 297篇 |
2007年 | 308篇 |
2006年 | 256篇 |
2005年 | 229篇 |
2004年 | 177篇 |
2003年 | 174篇 |
2002年 | 148篇 |
2001年 | 120篇 |
2000年 | 96篇 |
1999年 | 90篇 |
1998年 | 91篇 |
1997年 | 81篇 |
1996年 | 63篇 |
1995年 | 66篇 |
1994年 | 61篇 |
1993年 | 29篇 |
1992年 | 28篇 |
1991年 | 33篇 |
1990年 | 32篇 |
1989年 | 31篇 |
1988年 | 25篇 |
1987年 | 18篇 |
1986年 | 12篇 |
1985年 | 20篇 |
1984年 | 21篇 |
1983年 | 18篇 |
1982年 | 15篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 14篇 |
1978年 | 12篇 |
1977年 | 13篇 |
1976年 | 9篇 |
1973年 | 8篇 |
排序方式: 共有5603条查询结果,搜索用时 390 毫秒
1.
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
2.
Multi-sensor data fusion is an evolving technology whereby data from multiple sensor inputs are processed and combined. The data derived from multiple sensors can, however, be uncertain, imperfect, and conflicting. The present study is undertaken to help contribute to the continuous search for viable approaches to overcome the problems associated with data conflict and imperfection. Sensor readings, represented by belief functions, have to be fused according to their corresponding weights. Previous studies have often estimated the weights of sensor readings based on a single criterion. Mono-criteria approaches for the assessment of sensor reading weights are, however, often unreliable and inadequate for the reflection of reality. Accordingly, this work opts for the use of a multi-criteria decision aid. A modified Analytical Hierarchy Process (AHP) that incorporates several criteria is proposed to determine the weights of a sensor reading set. The approach relies on the automation of pairwise comparisons to eliminate subjectivity and reduce inconsistency. It assesses the weight of each sensor reading, and fuses the weighed readings obtained using a modified average combination rule. The efficiency of this approach is evaluated in a target recognition context. Several tests, sensitivity analysis, and comparisons with other approaches available in the literature are described. 相似文献
3.
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
4.
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
5.
6.
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
7.
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
8.
Agnieszka Kaamajska 《Mathematical Methods in the Applied Sciences》2006,29(11):1307-1325
The weak limits of sequences {f(uν)}ν∈? where uν's are vector‐valued µ‐measurable functions defined on a compact set Ω and f is (possibly) discontinuous are investigated. As shown by the author (J. Conv. Anal. (to appear)), they are described in terms of integral formulae involving parametrized measures independent of f, similarly as in the classical theorem by Young and its generalization due to DiPerna and Majda. In the present paper we describe the supports of the involved parametrized measures. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
9.
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
10.
基于校园网的实验管理系统的设计 总被引:2,自引:1,他引:1
主要讨论了应用实验室管理系统的必要性,并从用户需求分析、系统总体设计、功能模块的设计等方面对B/S实验室管理系统的开发进行了详细的阐述。 相似文献