全文获取类型
收费全文 | 4023篇 |
免费 | 562篇 |
国内免费 | 174篇 |
专业分类
化学 | 383篇 |
晶体学 | 5篇 |
力学 | 125篇 |
综合类 | 198篇 |
数学 | 1879篇 |
物理学 | 2169篇 |
出版年
2024年 | 8篇 |
2023年 | 34篇 |
2022年 | 305篇 |
2021年 | 280篇 |
2020年 | 147篇 |
2019年 | 116篇 |
2018年 | 93篇 |
2017年 | 143篇 |
2016年 | 179篇 |
2015年 | 126篇 |
2014年 | 239篇 |
2013年 | 255篇 |
2012年 | 169篇 |
2011年 | 226篇 |
2010年 | 212篇 |
2009年 | 240篇 |
2008年 | 243篇 |
2007年 | 249篇 |
2006年 | 201篇 |
2005年 | 177篇 |
2004年 | 141篇 |
2003年 | 140篇 |
2002年 | 111篇 |
2001年 | 82篇 |
2000年 | 70篇 |
1999年 | 52篇 |
1998年 | 55篇 |
1997年 | 48篇 |
1996年 | 44篇 |
1995年 | 52篇 |
1994年 | 48篇 |
1993年 | 23篇 |
1992年 | 22篇 |
1991年 | 19篇 |
1990年 | 26篇 |
1989年 | 30篇 |
1988年 | 21篇 |
1987年 | 20篇 |
1986年 | 10篇 |
1985年 | 21篇 |
1984年 | 12篇 |
1983年 | 11篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 9篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1972年 | 4篇 |
排序方式: 共有4759条查询结果,搜索用时 31 毫秒
991.
Miguel Ferrero 《Foundations of Physics》2003,33(4):665-676
It has been traditionally considered that Quantum Mechanics has two conceptual kinds of problems, namely, those related with local-realism and the so-called measurement problem. That is, the uniqueness of the result when we make a measurement. With the development of what is called generically Quantum Information Theory, a new form of the Copenhagen interpretation of the formalism has taken shape.(1) In this paper, we will analyse if this information interpretation is able to clarify these old problems. Although this interpretation seems to be the most promising approach we have, we have reached the conclusion that the answer cannot be given in a positive and clear way yet. 相似文献
992.
Erik J. Balder 《International Journal of Game Theory》2008,37(1):73-92
It is pointed out that Corollary 1 in a recent paper by Khan et al. (Int J Game Theory 34:91–104, 2006), presented there as
an extension of the Dvoretzky–Wald–Wolfowitz theorem, is a special case of Lyapunov’s theorem for Young measures (Balder in
Rend Instit Mat Univ Trieste 31 Suppl. 1:1–69) It is also pointed out that Theorems 1–4 in Khan et al. (Int J Game Theory
34:91–104, 2006) follow from a single strong purification per se result that is already contained, as an implementation of that Lyapunov theorem for Young measures, in the proof of Theorem
2.2.1 in Balder (J Econ Theory 102:437–470, 2002). 相似文献
993.
994.
本文介绍了正在研究和发展中的各种光电子信息材料,包括激光材料、光电子传感材料、光电子信息存储材料、光电子信息传输材料、光电子信息运算和处理材料,并展示了未来的光纤通信和光学计算机用材料的发展前景。 相似文献
995.
This paper presents a multiclass, multicriteria (cost versus time) logit-based traffic equilibrium assignment model in road networks served by advanced traveler information systems (ATIS). All users are differentiated by their own value of time (VOT) that follows some probability distribution. Users of each class, having their own VOT, are further divided into two groups, equipped and unequipped with ATIS respectively. The travel disutility received by each user is defined as a linear bi-criteria combination of travel time and monetary travel cost. It is assumed that all users make their route choices in a logit-based stochastic manner, but the equipped users have lower perception variation on the travel disutility than the unequipped due to the ATIS service. The model is formulated as a fixed-point problem and solved by the method of successive averages in conjunction with logit assignment. Numerical results show that the traditional single-class and/or single-criterion models may overestimate or underestimate the benefit from ATIS services. 相似文献
996.
系统模拟做为一种定量分析的手段,在管理中发挥着重要的作用,对离散系统模拟方法进行了讨论,建立了一个随机服务系统的模型,并通过Excel对其进行模拟,最后对该系统的性能进行了分析. 相似文献
997.
本文讨论了由N个同型部件和一个服务设备组成的机器服务模型,在服务设备绝对可靠,或服务设备具有指数寿命,修理工对其修理的时间为PH分布,这两种情况下求得了系统的平稳概率分布,从而求得机器系统和服务设备的稳态可靠性指标,并证明了它们的首次失效时间均服从PH分布,服务设备和修理工的忙期亦服从PH分布. 相似文献
998.
关于高速摄影系统的信息量 总被引:1,自引:0,他引:1
本文分别讨论了狭缝扫描高速摄影系统、分幅高速摄影系统以及网格高速摄影系统的信息量计算公式.在讨论分幅摄影系统时,指出了光快门作用对空间自由度的影响. 相似文献
999.
In decision analysis, difficulties of obtaining complete information about model parameters make it advisable to seek robust solutions that perform reasonably well across the full range of feasible parameter values. In this paper, we develop the Robust Portfolio Modeling (RPM) methodology which extends Preference Programming methods into portfolio problems where a subset of project proposals are funded in view of multiple evaluation criteria. We also develop an algorithm for computing all non-dominated portfolios, subject to incomplete information about criterion weights and project-specific performance levels. Based on these portfolios, we propose a project-level index to convey (i) which projects are robust choices (in the sense that they would be recommended even if further information were to be obtained) and (ii) how continued activities in preference elicitation should be focused. The RPM methodology is illustrated with an application using real data on road pavement projects. 相似文献
1000.