全文获取类型
收费全文 | 5642篇 |
免费 | 189篇 |
国内免费 | 29篇 |
专业分类
化学 | 3397篇 |
晶体学 | 35篇 |
力学 | 138篇 |
数学 | 981篇 |
物理学 | 1309篇 |
出版年
2023年 | 37篇 |
2022年 | 92篇 |
2021年 | 127篇 |
2020年 | 122篇 |
2019年 | 147篇 |
2018年 | 127篇 |
2017年 | 121篇 |
2016年 | 216篇 |
2015年 | 172篇 |
2014年 | 170篇 |
2013年 | 306篇 |
2012年 | 316篇 |
2011年 | 417篇 |
2010年 | 253篇 |
2009年 | 198篇 |
2008年 | 296篇 |
2007年 | 303篇 |
2006年 | 334篇 |
2005年 | 268篇 |
2004年 | 230篇 |
2003年 | 194篇 |
2002年 | 169篇 |
2001年 | 104篇 |
2000年 | 84篇 |
1999年 | 61篇 |
1998年 | 50篇 |
1997年 | 62篇 |
1996年 | 56篇 |
1995年 | 61篇 |
1994年 | 40篇 |
1993年 | 39篇 |
1992年 | 45篇 |
1991年 | 40篇 |
1990年 | 47篇 |
1989年 | 25篇 |
1988年 | 39篇 |
1987年 | 25篇 |
1985年 | 37篇 |
1984年 | 34篇 |
1983年 | 24篇 |
1982年 | 41篇 |
1981年 | 33篇 |
1980年 | 33篇 |
1979年 | 31篇 |
1978年 | 21篇 |
1977年 | 18篇 |
1976年 | 17篇 |
1975年 | 24篇 |
1974年 | 14篇 |
1973年 | 26篇 |
排序方式: 共有5860条查询结果,搜索用时 15 毫秒
2.
3.
4.
E. V. Zakharov A. G. Davydov Yu. V. Pimenov G. M. Tikhonov 《Computational Mathematics and Modeling》1991,2(1):79-84
Translated from Chislennye Metody Resheniya Obratnykh Zadach Matematicheskoi Fiziki, pp. 119–127. 相似文献
5.
6.
Panos M. Pardalos Wanpracha Chaovalitwongse Leonidas D. Iasemidis J. Chris Sackellares Deng-Shan Shiau Paul R. Carney Oleg A. Prokopyev Vitaliy A. Yatsenko 《Mathematical Programming》2004,101(2):365-385
There is growing evidence that temporal lobe seizures are preceded by a preictal transition, characterized by a gradual dynamical change from asymptomatic interictal state to seizure. We herein report the first prospective analysis of the online automated algorithm for detecting the preictal transition in ongoing EEG signals. Such, the algorithm constitutes a seizure warning system. The algorithm estimates STLmax, a measure of the order or disorder of the signal, of EEG signals recorded from individual electrode sites. The optimization techniques were employed to select critical brain electrode sites that exhibit the preictal transition for the warning of epileptic seizures. Specifically, a quadratically constrained quadratic 0-1 programming problem is formulated to identify critical electrode sites. The automated seizure warning algorithm was tested in continuous, long-term EEG recordings obtained from 5 patients with temporal lobe epilepsy. For individual patient, we use the first half of seizures to train the parameter settings, which is evaluated by ROC (Receiver Operating Characteristic) curve analysis. With the best parameter setting, the algorithm applied to all cases predicted an average of 91.7% of seizures with an average false prediction rate of 0.196 per hour. These results indicate that it may be possible to develop automated seizure warning devices for diagnostic and therapeutic purposes.Mathematics Subject Classification (1991):20E28, 20G40, 20C20 相似文献
7.
8.
Oleg Borodin 《Combinatorica》1993,13(1):121-125
The weight of an edge in a graph is the sum of the degrees of its end-vertices. It is proved that in each 3-polytope there exists either an edge of weight at most 13 for which both incident faces are triangles, or an edge of weight at most 10 which is incident with a triangle, or else an edge of weight at most 8. All the bounds 13, 10, and 8 are sharp and attained independently of each other. 相似文献
9.
S. Yu. Davydov 《Technical Physics》2002,47(1):92-96
A relationship is analyzed between the ionization energy of atoms I and the work function φ of a metal composed of these atoms. The transition energy ∑=I?φ is assumed to be the sum of kinetic K and coulombic C contributions. Contribution K is calculated in the framework of a model of uniform gas of quasi-free electrons, and C is determined from experimental values of Σ. Calculations performed for a wide range of metals have shown that the dimensionless coefficients determining the Coulombic contribution C differ insignificantly between various groups of metals. The relationships obtained have been used for determining the work function of binary alloys. 相似文献
10.
Laura Bader Nicola Durante Maska Law Guglielmo Lunardon Tim Penttila 《Designs, Codes and Cryptography》2003,29(1-3):41-50
We do the tentative beginnings of a study of BLT-sets of generalised quadrangles via their symmetries. In particular, the study of whorls about a line leads us to hyperbolic reflections preserving a BLT-set of Q(4, q). 相似文献