全文获取类型
收费全文 | 2334篇 |
免费 | 603篇 |
国内免费 | 118篇 |
专业分类
化学 | 524篇 |
晶体学 | 4篇 |
力学 | 162篇 |
综合类 | 68篇 |
数学 | 517篇 |
物理学 | 1780篇 |
出版年
2024年 | 5篇 |
2023年 | 30篇 |
2022年 | 88篇 |
2021年 | 93篇 |
2020年 | 58篇 |
2019年 | 59篇 |
2018年 | 63篇 |
2017年 | 92篇 |
2016年 | 96篇 |
2015年 | 145篇 |
2014年 | 179篇 |
2013年 | 196篇 |
2012年 | 153篇 |
2011年 | 186篇 |
2010年 | 127篇 |
2009年 | 176篇 |
2008年 | 197篇 |
2007年 | 124篇 |
2006年 | 140篇 |
2005年 | 131篇 |
2004年 | 102篇 |
2003年 | 111篇 |
2002年 | 73篇 |
2001年 | 75篇 |
2000年 | 57篇 |
1999年 | 51篇 |
1998年 | 42篇 |
1997年 | 29篇 |
1996年 | 31篇 |
1995年 | 18篇 |
1994年 | 15篇 |
1993年 | 12篇 |
1992年 | 15篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 9篇 |
1987年 | 10篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1977年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有3055条查询结果,搜索用时 15 毫秒
991.
The value of the stochastic solution in stochastic linear programs with fixed recourse 总被引:1,自引:0,他引:1
John R. Birge 《Mathematical Programming》1982,24(1):314-325
Stochastic linear programs have been rarely used in practical situations largely because of their complexity. In evaluating these problems without finding the exact solution, a common method has been to find bounds on the expected value of perfect information. In this paper, we consider a different method. We present bounds on the value of the stochastic solution, that is, the potential benefit from solving the stochastic program over solving a deterministic program in which expected values have replaced random parameters. These bounds are calculated by solving smaller programs related to the stochastic recourse problem.This paper is an extension of part of the author's dissertation in the Department of Operations Research, Stanford University, Stanford, California. The research was supported at Stanford by the Department of Energy under Contract DE-AC03-76SF00326, PA#DE-AT03-76ER72018, Office of Naval Research under Contract N00014-75-C-0267 and the National Science Foundation under Grants MCS76-81259, MCS-7926009 and ECS-8012974 (formerly ENG77-06761). 相似文献
992.
Martine Rousseau 《Journal of statistical physics》1973,8(4):341-352
We consider two definitions of entropy: thermodynamic entropy and signal entropy. We compare their value for the class of generalized Gaussian fields. The first definition is well adapted to monomode stationary fields, while the second one is bounded only for multimode fields. We prove that these two notions are definitely different, for example, the real Gaussian field has a maximum signal entropy and a minimum thermodynamic entropy (among the Gaussian fields). 相似文献
993.
994.
995.
可变抽样区间的单边控制图 总被引:4,自引:0,他引:4
利用质量控制图监督生产过程时 ,通常每隔固定时间从过程抽取固定容量的样本。本文在前文[1] 的基础上设计具有可变抽样区间的单边标准差 (S)图、极差 (R)图和不合格品数 (np)图。计算了这三个图发信号前的平均样本数和平均时间 ,并同固定抽样区间的常规控制图作比较。所设计的控制图能缩短过程失控时间从而减少不合格品数。 相似文献
996.
997.
M. A. Man'ko 《Journal of Russian Laser Research》2002,23(5):433-448
A generic electromagnetic signal described by Maxwell equations both in vacuum and media is considered in the tomographic representation. The Ville–Wigner phase-space representation of the electromagnetic field is also discussed. Relations between different representations of the electromagnetic signal are elucidated. The connection of the Fourier analysis of the electromagnetic signal and other mathematical approaches like the Radon transform of the analytic signal is presented. The distinguishing property of the tomogram to coincide with the probability density of a random variable considered in a reference frame in the signal's phase space is pointed out. The entropy of the signal related to the probability density is studied. 相似文献
998.
999.
Complex periodical sequences with lower autocorrelation values are used in CDMA communication systems and cryptography. In this paper we present new nonexistence results on perfect p-ary sequences and almost p-ary sequences and related difference sets by using some knowledge on cyclotomic fields and their subfields. 相似文献
1000.