全文获取类型
收费全文 | 14204篇 |
免费 | 174篇 |
国内免费 | 428篇 |
专业分类
化学 | 4277篇 |
晶体学 | 10篇 |
力学 | 428篇 |
综合类 | 57篇 |
数学 | 5705篇 |
物理学 | 4329篇 |
出版年
2024年 | 6篇 |
2023年 | 43篇 |
2022年 | 112篇 |
2021年 | 103篇 |
2020年 | 156篇 |
2019年 | 148篇 |
2018年 | 155篇 |
2017年 | 157篇 |
2016年 | 187篇 |
2015年 | 96篇 |
2014年 | 214篇 |
2013年 | 863篇 |
2012年 | 523篇 |
2011年 | 639篇 |
2010年 | 532篇 |
2009年 | 2934篇 |
2008年 | 2346篇 |
2007年 | 1030篇 |
2006年 | 560篇 |
2005年 | 465篇 |
2004年 | 421篇 |
2003年 | 289篇 |
2002年 | 252篇 |
2001年 | 216篇 |
2000年 | 187篇 |
1999年 | 154篇 |
1998年 | 248篇 |
1997年 | 222篇 |
1996年 | 93篇 |
1995年 | 281篇 |
1994年 | 230篇 |
1993年 | 201篇 |
1992年 | 260篇 |
1991年 | 226篇 |
1990年 | 84篇 |
1989年 | 80篇 |
1988年 | 47篇 |
1987年 | 10篇 |
1986年 | 9篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1971年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Several authors have studied the uniform estimate for the tail probabilities of randomly weighted sumsa.ud their maxima. In this paper, we generalize their work to the situation thatis a sequence of upper tail asymptotically independent random variables with common distribution from the is a sequence of nonnegative random variables, independent of and satisfying some regular conditions. Moreover. no additional assumption is required on the dependence structureof {θi,i≥ 1). 相似文献
992.
Vladimir I. Bogachev Andrey Yu. Pilipenko Alexander V. Shaposhnikov 《Journal of Mathematical Analysis and Applications》2014
We study extensions of Sobolev and BV functions on infinite-dimensional domains. Along with some positive results we present a negative solution of the long-standing problem of existence of Sobolev extensions of functions in Gaussian Sobolev spaces from a convex domain to the whole space. 相似文献
993.
JEONG-HAN KANG SEUNG-YEAL HA KYUNGKEUN KANG EUNHEE JEONG 《The Journal of mathematical sociology》2014,38(1):47-71
When cultural tastes are not neutral but hierarchically matched to social status, people assimilate themselves to higher status by consuming cultural goods while distinguishing themselves from lower status by developing new tastes. Extending the Cucker-Smale model for mutual influence among agents, we examine when and how many cultural classes emerge from continuous distributions of tastes and what conditions those classes satisfy, through the assimilation-distinction mechanism. We simulate the models with different initial distributions of tastes (uniform, normal, and chi-square), given various ranges of 2 parameters: (a) the strength and (b) the range of distinction relative to assimilation. Tastes are flocking and cultural classes emerge when the range of assimilation is much larger than that of distinction. The number of classes increases with the strength of distinction, whereas the distance between classes equals the range of distinction. Some properties of emergent classes are mathematically proved. First, in a two-class system, the stronger distinction, the larger the upper class. Second, in a three-class system, the middle class is necessarily larger than the lower class and likely larger than the upper class. Third, a 3-class system cannot emerge if distinction is weaker than assimilation. These properties are universal and do not depend on the initial distribution of cultural tastes. This independence predicts homogeneous cultural classes emerging across different social conditions. Also, the cultural middle class as the largest group may explain why subjective class consciousness is often higher than objective position. Unless assimilating efforts can reach an infinite range, there emerges a cultural outcast at the lowest end of the cultural hierarchy. 相似文献
994.
ANDREAS TUTIĆ 《The Journal of mathematical sociology》2014,38(3):219-232
The mixed-strategy equilibrium applied to the volunteer's dilemma (Diekmann, 1985) predicts that the probability that at least 1 bystander volunteers decreases, if the number of bystander increases. I argue that this prediction lacks empirical support and demonstrate that an alternative solution concept from the literature on bounded rationality, the procedurally rational equilibrium (Osborne &; Rubinstein, 1998), yields alternative predictions. I supply some empirical evidence that the alternative solution concept fares better in explaining observed behavior in the volunteer's dilemma. 相似文献
996.
围绕两个典型迭代数列的构造问题,以问题为驱动,提出一种生成迭代数列的新方法,并通过数值实验或理论证明验证迭代数列的收敛性. 相似文献
997.
998.
We obtain a global unique continuation result for the differential inequality |(i∂t+Δ)u|?|V(x)u| in Rn+1. This is the first result on global unique continuation for the Schrödinger equation with time-independent potentials V(x) in Rn. Our method is based on a new type of Carleman estimates for the operator i∂t+Δ on Rn+1. As a corollary of the result, we also obtain a new unique continuation result for some parabolic equations. 相似文献
999.
徐远 《数学的实践与认识》2014,(12)
引入了集列的极限运算与二元集运算之间的共轭可交换性的概念,讨论了常见的和重要的集列的极限运算与集代数运算之间所具有的共轭可交换性质,在一般的情形下证明了共轭可交换性是集类的极限运算生成类对集代数运算具有封闭性的一个充分条件,使得集合形式的单调类定理的理论得到了统一的解释,并且证明更简单,思路更清晰,最后还给出了一个新的集合形式的单调类定理. 相似文献
1000.
中等收入人口的确定对于分析一个社会的经济发展,稳定性具有重要的意义.洛伦兹曲线是一种分析中等收入的经典工具.本文提出一种具有更高拟合精度的洛伦兹曲线模型.并基于其几何特征,考虑社会的贫富程度与贫富分化因素,建立了收入空间法与人口空间法的优化模型. 相似文献