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   28738篇
  免费   830篇
  国内免费   229篇
化学   19535篇
晶体学   133篇
力学   650篇
综合类   1篇
数学   5425篇
物理学   4053篇
  2022年   121篇
  2021年   282篇
  2020年   356篇
  2019年   322篇
  2018年   280篇
  2017年   297篇
  2016年   617篇
  2015年   635篇
  2014年   680篇
  2013年   1419篇
  2012年   1439篇
  2011年   1739篇
  2010年   973篇
  2009年   847篇
  2008年   1490篇
  2007年   1489篇
  2006年   1586篇
  2005年   1425篇
  2004年   1349篇
  2003年   1116篇
  2002年   1057篇
  2001年   464篇
  2000年   422篇
  1999年   406篇
  1998年   394篇
  1997年   440篇
  1996年   410篇
  1995年   370篇
  1994年   400篇
  1993年   350篇
  1992年   324篇
  1991年   329篇
  1990年   282篇
  1989年   284篇
  1988年   264篇
  1987年   221篇
  1986年   254篇
  1985年   362篇
  1984年   371篇
  1983年   318篇
  1982年   347篇
  1981年   313篇
  1980年   337篇
  1979年   270篇
  1978年   302篇
  1977年   279篇
  1976年   225篇
  1975年   192篇
  1974年   195篇
  1973年   164篇
排序方式: 共有10000条查询结果,搜索用时 173 毫秒
81.
Preface     
This issue of Journal of Thermal Analysis and Calorimetry contains selected papers based on presentations in the field of thermal characteristics of advanced polymer systems presented at the 8th International Symposium on Polymers for Advanced Technologies (PAT 2005) held in Budapest, September 2005. Guest Editors  相似文献   
82.
In this paper, the possibility of using the gradients of the temperature and of the internal parameters as additional state variables in Continuum Thermodynamics is considered. The expressions of the two principles are discussed and Clausius–Duhem inequality is derived under an appropriate statement of the internal entropy production. Several formulations are proposed and compared to existing results in the literature. To cite this article: P. Ireman, Q.S. Nguyen, C. R. Mecanique 332 (2004).  相似文献   
83.
84.
A new parallel storm surge model, the Parallel Environmental Model (PEM), is developed and tested by comparisons with analytic solutions. The PEM is a 2‐D vertically averaged, wetting and drying numerical model and can be operated in explicit, semi‐implicit and fully implicit modes. In the implicit mode, the propagation, Coriolis and bottom friction terms can all be treated implicitly. The advection and diffusion terms are solved with a parallel Eulerian–Lagrangian scheme developed for this study. The model is developed specifically for use on parallel computer systems and will function accordingly in either explicit of implicit modes. Storm boundary conditions are based on a simple exponential decay of pressure from the centre of a storm. The simulated flooding caused by a major Category 5 hurricane making landfall in the Indian River Lagoon, Florida is then presented as an example application of the PEM. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   
85.
A cube factorization of the complete graph on n vertices, Kn, is a 3‐factorization of Kn in which the components of each factor are cubes. We show that there exists a cube factorization of Kn if and only if n ≡ 16 (mod 24), thus providing a new family of uniform 3‐factorizations as well as a partial solution to an open problem posed by Kotzig in 1979. © 2004 Wiley Periodicals, Inc.  相似文献   
86.
Duality principles in Gabor theory such as the Ron–Shen duality principle and the Wexler–Raz biorthogonality relations play a fundamental role for analyzing Gabor systems. In this article we present a general approach to derive duality principles in abstract frame theory. For each sequence in a separable Hilbert space we define a corresponding sequence dependent only on two orthonormal bases. Then we characterize exactly properties of the first sequence in terms of the associated one, which yields duality relations for the abstract frame setting. In the last part we apply our results to Gabor systems.  相似文献   
87.
88.
Deformation quantization is a powerful tool for quantizing theories with bosonic and fermionic degrees of freedom. The star products involved generate the mathematical structures which have recently been used in attempts to analyze the algebraic properties of quantum field theory. In the context of quantum mechanics they provide a quantization procedure for systems with either bosonic or fermionic degrees of freedom. We illustrate this procedure for a number of physical examples, including bosonic, fermionic, and supersymmetric oscillators. We show how non-relativistic and relativistic particles with spin can be naturally described in this framework.  相似文献   
89.
A horizontal translation of a function is the focus of this study. We examine the explanations provided by secondary school students and secondary school teachers to a translation of a function, focusing on the example of the parabola y=(x−3)2 and its relationship to y=x2. The participants’ explanations focused on attending to patterns, locating the zero of the function, and the point-wise calculation of function values. The results confirm that the horizontal shift of the parabola is, at least initially, inconsistent with expectations and counterintuitive to most participants. We articulate possible sources of this perceived inconsistency and describe a pedagogical approach aimed at resolving it.  相似文献   
90.
Since a comprehensive survey published in 1999 [1] much work was done in standardizing measuring methods to characterize the surface geometry of dispersed and/or porous solids and to certify reference materials. The present paper is an extension of a short communication [2]. It gives a survey on existing standards and reports on new drafts and proposals.  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