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   85篇
  免费   5篇
  国内免费   2篇
化学   32篇
力学   5篇
数学   40篇
物理学   15篇
  2023年   1篇
  2021年   4篇
  2019年   3篇
  2018年   2篇
  2017年   5篇
  2016年   4篇
  2015年   5篇
  2014年   3篇
  2013年   10篇
  2012年   4篇
  2011年   3篇
  2010年   5篇
  2009年   4篇
  2008年   6篇
  2007年   3篇
  2006年   6篇
  2005年   5篇
  2004年   2篇
  2003年   2篇
  2002年   1篇
  2001年   4篇
  2000年   1篇
  1999年   1篇
  1996年   1篇
  1989年   1篇
  1984年   1篇
  1982年   1篇
  1981年   2篇
  1980年   2篇
排序方式: 共有92条查询结果,搜索用时 15 毫秒
51.
We present a new class of black hole solutions with a minimally coupled scalar field in the presence of a negative cosmological constant. We consider an one-parameter family of self-interaction potentials parametrized by a dimensionless parameter g. When g = 0, we recover the conformally invariant solution of the Martinez–Troncoso–Zanelli (MTZ) black hole. A non-vanishing g signals the departure from conformal invariance. Thermodynamically, there is a critical temperature at vanishing black hole mass, where a higher-order phase transition occurs, as in the case of the MTZ black hole. Additionally, we obtain a branch of hairy solutions which undergo a first-order phase transition at a second critical temperature which depends on g and it is higher than the MTZ critical temperature. As g → 0, this second critical temperature diverges.  相似文献   
52.
We provide lower \(L^{q}\) and weak \(L^{q}\)-bounds for the localized dyadic maximal operator on \(\mathbb {R}^{n}\), when the local \(L^{1}\) and the local \(L^{p}\) norms of the function are given. We actually do that in the more general context of homogeneous trees in probability spaces.  相似文献   
53.
We precisely evaluate Bellman-type functions for the dyadic maximal operator on \(\mathbb {R}^{n}\) and of maximal operators on martingales related to local Lorentz-type estimates. Using a type of symmetrization principle, introduced for the dyadic maximal operator in earlier works of the authors, we precisely evaluate the supremum of the Lorentz quasinorm of the maximal operator on a function \(\phi \) when the integral of \(\phi \) is fixed and also the same Lorentz quasinorm of \(\phi \) is fixed. Also we find the corresponding supremum when the integral of \(\phi \) is fixed and several weak type conditions are given.  相似文献   
54.
We present the basic theory of denesting nested square roots, from an elementary point of view, suitable for lower level coursework. Necessary and sufficient conditions are given for direct denesting, where the nested expression is rewritten as a sum of square roots of rational numbers, and for indirect denesting, where the nested expression is rewritten as a sum of fourth-order roots of rational numbers. The theory is illustrated with several solved examples.  相似文献   
55.
The deformation of a rectangular block into an annular wedge is studied with respect to the state of swelling interior to the block. Nonuniform swelling fields are shown to generate these flexure deformations in the absence of resultant forces and bending moments. Analytical expressions for the deformation fields demonstrate these effects for both incompressible and compressible generalizations of conventional hyperelastic materials. Existing results in the absence of a swelling agent are recovered as special cases.  相似文献   
56.
We investigate, within the framework of Zermelo‐Fraenkel set theory ZF, the interrelations between weak forms of the Axiom of Choice AC restricted to sets of reals. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
57.
In this paper we develop an interactive decision analysis approach to treat a large scale bicriterion integer programming problem, addressing a real world assembly line scheduling problem of a manufacturing company. This company receives periodically a set of orders for the production of specific items (jobs) through a number of specialised production (assembly) lines. The paper presents a non compensatory approach based on an interactive implementation of the ε-constraint method that enables the decision maker to achieve a satisfactory goal for each objective separately. In fact, the method generates and evaluates a large number of non dominated solutions that constitute a representative sample of the criteria ranges. The experience with a specific numerical example shows the efficiency and usefulness of the proposed model in solving large scale bicriterion industrial integer programming problems, highlighting at the same time the modelling limitations.  相似文献   
58.
This paper presents a straightforward procedure for using Renormalization Group methods to solve a significant variety of perturbation problems, including some that result from applying a nonlinear version of variation of parameters. A regular perturbation procedure typically provides asymptotic solutions valid for bounded t values as a positive parameter ε tends to zero. One can eliminate secular terms by introducing a slowly‐varying amplitude obtained as a solution of an amplitude equation on intervals where is bounded. With sufficient stability hypotheses, the results may even hold for all . These ideas are illustrated for a number of nontrivial problems involving ordinary differential equations.  相似文献   
59.
60.
The synthesis of a water‐soluble copolymer containing quinoline groups, P(DMAM‐co‐SDPQ), through free radical copolymerization of N,N‐dimethylacrylamide, DMAM, with 2,4‐diphenyl‐6‐(4‐vinylphenyl)quinoline, SDPQ, is presented and the optical properties of the final product are investigated in aqueous solution as a function of pH. It is found that the emission peak of SDPQ is red‐shifted from 411 to 484 nm with decreasing pH, due to the protonation of quinoline groups at low pH, suggesting that this copolymer may function as a luminescent pH‐indicator. Moreover, the copolymer exhibits the characteristics of a luminescent pH‐detector within the pH range 2 < pH < 4, as in this pH region the ratio of the emission intensity at 411 nm over that at 484 nm changes linearly in a logarithmic scale with the pH of the solution. Finally, the formation of less polar quinoline clusters in the aqueous P(DMAM‐co‐SDPQ) solution upon increasing pH was detected through Nile red probing. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 2078–2083, 2010  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