首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   98篇
  免费   6篇
  国内免费   5篇
化学   17篇
力学   3篇
数学   72篇
物理学   17篇
  2022年   1篇
  2021年   1篇
  2020年   2篇
  2019年   8篇
  2018年   1篇
  2017年   3篇
  2016年   3篇
  2015年   1篇
  2014年   2篇
  2013年   2篇
  2012年   6篇
  2011年   2篇
  2010年   1篇
  2009年   7篇
  2008年   11篇
  2007年   7篇
  2006年   8篇
  2005年   6篇
  2004年   7篇
  2003年   1篇
  2002年   5篇
  2001年   3篇
  2000年   2篇
  1999年   2篇
  1998年   2篇
  1996年   3篇
  1994年   3篇
  1993年   1篇
  1988年   2篇
  1981年   1篇
  1980年   1篇
  1978年   1篇
  1977年   1篇
  1975年   1篇
  1974年   1篇
排序方式: 共有109条查询结果,搜索用时 15 毫秒
101.
We prove certain optimal systolic inequalities for a closed Riemannian manifold , depending on a pair of parameters, and . Here  is the dimension of , while is its first Betti number. The proof of the inequalities involves constructing Abel-Jacobi maps from to its Jacobi torus  , which are area-decreasing (on -dimensional areas), with respect to suitable norms. These norms are the stable norm of , the conformally invariant norm, as well as other -norms. Here we exploit -minimizing differential 1-forms in cohomology classes. We characterize the case of equality in our optimal inequalities, in terms of the criticality of the lattice of deck transformations of  , while the Abel-Jacobi map is a harmonic Riemannian submersion. That the resulting inequalities are actually nonvacuous follows from an isoperimetric inequality of Federer and Fleming, under the assumption of the nonvanishing of the homology class of the lift of the typical fiber of the Abel-Jacobi map to the maximal free abelian cover.

  相似文献   

102.
Let X be a space of homogenous type and ψ: X × [0,∞) → [0,∞) be a growth function such that ψ(·,t) is a Muckenhoupt weight uniformly in t and ψ(x,·) an Orlicz function of uniformly upper type 1 and lower type p ∈(0,1].In this article,the authors introduce a new Musielak–Orlicz BMO-type space BMOψA(X) associated with the generalized approximation to the identity,give out its basic properties and establish its two equivalent characterizations,respectively,in terms of the spaces BMOψA,max(X) and BMOψA(X).Moreover,two variants of the John–Nirenberg inequality on BMOψA(X) are obtained.As an application,the authors further prove that the space BMOψΔ1/2(Rn),associated with the Poisson semigroup of the Laplace operator Δ on Rn,coincides with the space BMOψ(Rn) introduced by Ky.  相似文献   
103.
In this paper, we first establish a Schwarz–Pick lemma for higher-order derivatives of planar harmonic mappings, and apply it to obtain univalency criteria. Then we discuss distortion theorems,Lipschitz continuity and univalency of planar harmonic mappings defined in the unit disk with linearly connected images.  相似文献   
104.
《Optimization》2012,61(3):321-322
In this article we establish necessary conditions for local Pareto and weak minima of multiobjective programming problems involving inequality, equality and set constraints in Banach spaces in terms of convexificators.  相似文献   
105.
Let D■R2 be a Jordan domain,D*=R2\D,the exterior of D.In this article,the authors obtained the following results:(1)If D is a John disk,then D is an outer linearly locally connected domain;(2)If D* is a John disk,then D is an inner linearly locally connected domain;(3)A homeomorphism f:R 2 →R 2 is a quasiconformal mapping if and only if f(D)is a John disk for any John disk D■R 2 ;and(4)If D is a bounded quasidisk,then D is a John disk,and there exists an unbounded quasidisk which is not a John disk.  相似文献   
106.
This article completes the authors’s series on stability in the Liouville theorem on the Heisenberg group. We show that every mapping with bounded distortion on a John domain of the Heisenberg group is approximated by a conformal mapping with order of closeness √K ? 1 in the uniform norm and with order of closeness K ? 1 in the Sobolev L p 1 -norm for all p < C/K?1. We construct two examples, demonstrating the asymptotic sharpness of our results.  相似文献   
107.
In this paper,we consider the extremal problem of the lp-norm:min {lp(TK),o∈TK■L,T∈GL(n)},where K,L are two convex bodies in Rn.Using the optimization theorem of John,we give necessary conditions for K to be in extremal position in terms of a decomposition of the identity.Furthermore,the weaker optimization problem,min{(lp(TK))p:TK■B2n,TK∩Sn-1≠,T∈GL(n)},is also considered.As an application,the geometric distance between the unit ball B2n and a centrally symmetric convex body K is obtained.  相似文献   
108.
This account of the history of the Bardeen–Cooper–Schrieffer theory of superconductivity has its roots in an assignment that Quin Luttinger designed for me in 1963 when I was his graduate student. It improves on my student work by tracing the story from historical source materials as well as published papers, thus reflecting the contingencies and human elements that shape all research in physics. I also made an attempt to portray general features of how John Bardeen approached solving problems in physics.  相似文献   
109.
Benson真有效意义下向量集值优化的广义Fritz John条件   总被引:6,自引:1,他引:5  
引入了一种有关集值映射的切导数和强、弱*伪凸的概念。借助凸集分离定理及锥分离定理建立了Benson真有效意义下向量集值优化导数型的FritzJohn最优性条件,并对条件的充分性进行了讨论。当特殊到单值映射时这些最优性条件与经典的结果完全吻合。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号