全文获取类型
收费全文 | 53篇 |
免费 | 27篇 |
国内免费 | 6篇 |
专业分类
化学 | 2篇 |
力学 | 2篇 |
综合类 | 2篇 |
数学 | 55篇 |
物理学 | 25篇 |
出版年
2022年 | 2篇 |
2021年 | 1篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2015年 | 3篇 |
2014年 | 1篇 |
2013年 | 2篇 |
2012年 | 5篇 |
2011年 | 8篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 6篇 |
2007年 | 3篇 |
2006年 | 5篇 |
2005年 | 6篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1988年 | 2篇 |
排序方式: 共有86条查询结果,搜索用时 15 毫秒
41.
The definition and criterion of the form invariance of Nielsen equations are given. The relation between the form invariance and the Noether symmetry is studied. Some examples are given to illustrate the application of the result. 相似文献
42.
王云峰 《纯粹数学与应用数学》1993,(1)
本文在[1],[3]的基础上引入了离散动力系统不动点类的Nielsen-数,讨论了Nielsen-数的同伦性质,得到利用Nielesn-数估计离散动力系统不动点个数的几个结果,为地一步研究该系统不动点的个数问题提供了有用的工具。 相似文献
43.
The problem on the least number of fixed points of an equivariant map of a compact polyhedron on which a finite group acts is considered. For such a map, the least number of fixed points and the least number of fixed orbits are estimated in terms of invariants of the type of Nielsen numbers. The estimates obtained are sharp. The results are similar to those of P. Wong, but their assumptions are essentially weaker. Some notations are refined. The proofs are constructive. 相似文献
44.
45.
A. L. Talambutsa 《Mathematical Notes》2005,78(3-4):569-572
In the paper, the set of exponents of exponential growth (growth exponents) for a finitely generated group with respect to all possible generators of this group is studied. It is proved that the greatest lower bound of this set is attained for the free products of a cyclic group of prime order and a free group of finite rank. 相似文献
46.
通过研究拓扑空间上幂等自映射在基本群上诱导的作用和点同伦,得到与之同伦的,具有较好性质的自映射。并利用自映射这些性质,得到幂等自映射的Melscn数不超过1的结论。同时亦为高阶同伦群为平凡的拓扑空间上的自映射的Nielsen数的计算提供了一个新思路。 相似文献
47.
研究非保守Nielsen方程由形式不变性直接导致的非Noether守恒量.函数对时间的全导数采 用沿运动轨道曲线的方式,给出非保守Nielsen方程的非点的形式不变性的定义和判据,并 研究其Noether守恒量.得到形式不变性导致非Noether守恒量的条件以及守恒量的形式,并 给出三种特殊情形的推论.举例说明结果的应用.
关键词:
Nielsen方程
形式不变性
非Noether守恒量 相似文献
48.
49.
50.
In this paper, we consider two main families of bivariate distributions with exponential marginals for a couple of random variables . More specifically, we derive closed-form expressions for the distribution of the sum , the TVaR of and the contributions of each risk under the TVaR-based allocation rule. The first family considered is a subset of the class of bivariate combinations of exponentials, more precisely, bivariate combinations of exponentials with exponential marginals. We show that several well-known bivariate exponential distributions are special cases of this family. The second family we investigate is a subset of the class of bivariate mixed Erlang distributions, namely bivariate mixed Erlang distributions with exponential marginals. For this second class of distributions, we propose a method based on the compound geometric representation of the exponential distribution to construct bivariate mixed Erlang distributions with exponential marginals. Notably, we show that this method not only leads to Moran–Downton’s bivariate exponential distribution, but also to a generalization of this bivariate distribution. Moreover, we also propose a method to construct bivariate mixed Erlang distributions with exponential marginals from any absolutely continuous bivariate distributions with exponential marginals. Inspired from Lee and Lin (2012), we show that the resulting bivariate distribution approximates the initial bivariate distribution and we highlight the advantages of such an approximation. 相似文献