全文获取类型
收费全文 | 4055篇 |
免费 | 359篇 |
国内免费 | 433篇 |
专业分类
化学 | 1143篇 |
晶体学 | 18篇 |
力学 | 117篇 |
综合类 | 138篇 |
数学 | 2483篇 |
物理学 | 948篇 |
出版年
2024年 | 6篇 |
2023年 | 20篇 |
2022年 | 46篇 |
2021年 | 85篇 |
2020年 | 104篇 |
2019年 | 93篇 |
2018年 | 101篇 |
2017年 | 114篇 |
2016年 | 116篇 |
2015年 | 76篇 |
2014年 | 163篇 |
2013年 | 354篇 |
2012年 | 223篇 |
2011年 | 236篇 |
2010年 | 173篇 |
2009年 | 242篇 |
2008年 | 266篇 |
2007年 | 274篇 |
2006年 | 240篇 |
2005年 | 211篇 |
2004年 | 210篇 |
2003年 | 209篇 |
2002年 | 193篇 |
2001年 | 130篇 |
2000年 | 122篇 |
1999年 | 142篇 |
1998年 | 126篇 |
1997年 | 107篇 |
1996年 | 78篇 |
1995年 | 55篇 |
1994年 | 58篇 |
1993年 | 40篇 |
1992年 | 35篇 |
1991年 | 26篇 |
1990年 | 22篇 |
1989年 | 26篇 |
1988年 | 17篇 |
1987年 | 18篇 |
1986年 | 11篇 |
1985年 | 8篇 |
1984年 | 13篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1977年 | 6篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1936年 | 2篇 |
排序方式: 共有4847条查询结果,搜索用时 296 毫秒
1.
2.
In this paper, the authors studied certain properties of the estimate of Liang and Krishnaiah (1985, J. Multivariate Anal. 16, 162–172) for multivariate binary density. An alternative shrinkage estimate is also obtained. The above results are generalized to general orthonormal systems. 相似文献
3.
We examine two criteria for balance of a gain graph, one based on binary cycles and one on circles. The graphs for which each criterion is valid depend on the set of allowed gain groups. The binary cycle test is invalid, except for forests, if any possible gain group has an element of odd order. Assuming all groups are allowed, or all abelian groups, or merely the cyclic group of order 3, we characterize, both constructively and by forbidden minors, the graphs for which the circle test is valid. It turns out that these three classes of groups have the same set of forbidden minors. The exact reason for the importance of the ternary cyclic group is not clear. © 2005 Wiley Periodicals, Inc. J Graph Theory 相似文献
4.
5.
6.
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
7.
采用振荡管式数字密度计分别测定甲醇、乙醇、正丙醇、异丙醇、丁正醇和异丁醇与N-甲基哌嗪组成的二元体系在298.15K下的密度,计算了超额摩尔体积、超额偏摩尔体积、表观摩尔体积、偏摩尔体积等体积性质,从分子相互作用角度讨论了这些二元体系的体积性质的变化规律,为N-甲基哌嗪的开发和研究提供基础数据和信息。 相似文献
8.
Patrick Dehornoy 《Algebra Universalis》2002,48(2):223-248
We solve the word problem of the identity x(yz) = (xy)(yz) by investigating a certain group describing the geometry of that identity. We also construct a concrete realization of the
one-generated free algebra relative to the above identity.
Received March 23, 2001; accepted in final form July 6, 2002. 相似文献
9.
凸序列不等式的控制证明 总被引:2,自引:0,他引:2
利用控制不等式理论简洁地证明了一类凸序列不等式 (包括著名的 Nanson不等式的几个推广 ) ,并给出若干应用 . 相似文献
10.
James Murdock 《Journal of Differential Equations》2004,205(2):424-465
Hypernormal forms (unique normal forms, simplest normal forms) are investigated both from the standpoint of foundational theory and algorithms suitable for use with computer algebra. The Baider theory of the Campbell-Hausdorff group is refined, by a study of its subgroups, to determine the smallest substages into which the hypernormalization process can be divided. This leads to a linear algebra algorithm to compute the generators needed for each substage with the least amount of work. A concrete interpretation of Jan Sanders’ spectral sequence for hypernormal forms is presented. Examples are given, and a proof is given for a little-known theorem of Belitskii expressing the hypernormal form space (in the inner product style) as the kernel of a higher-order differential operator. 相似文献