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   104261篇
  免费   1026篇
  国内免费   544篇
化学   42033篇
晶体学   971篇
力学   7323篇
综合类   1篇
数学   36324篇
物理学   19179篇
  2021年   182篇
  2020年   267篇
  2019年   322篇
  2018年   10602篇
  2017年   10409篇
  2016年   6517篇
  2015年   1228篇
  2014年   790篇
  2013年   1713篇
  2012年   4994篇
  2011年   11957篇
  2010年   6403篇
  2009年   6657篇
  2008年   7957篇
  2007年   10117篇
  2006年   1715篇
  2005年   2772篇
  2004年   2816篇
  2003年   3056篇
  2002年   1985篇
  2001年   548篇
  2000年   542篇
  1999年   364篇
  1998年   422篇
  1997年   439篇
  1996年   554篇
  1995年   434篇
  1994年   377篇
  1993年   397篇
  1992年   342篇
  1991年   320篇
  1990年   295篇
  1989年   326篇
  1988年   333篇
  1987年   313篇
  1986年   313篇
  1985年   450篇
  1984年   501篇
  1983年   385篇
  1982年   476篇
  1981年   456篇
  1980年   402篇
  1979年   392篇
  1978年   402篇
  1977年   368篇
  1976年   309篇
  1975年   301篇
  1974年   284篇
  1973年   280篇
  1972年   166篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Patnaik  Sansit  Hollkamp  John P.  Sidhardh  Sai  Semperlotti  Fabio 《Meccanica》2022,57(4):757-773
Meccanica - The advancement of manufacturing techniques has led to a rapid increase in the design and fabrication of periodic and architectured materials for a variety of dynamics and wave...  相似文献   
2.
3.
4.
Algebras and Representation Theory - We would like to correct two errors in our paper Involutions of type G2 over a field of characteristic 2 [2].  相似文献   
5.
6.
Measuring angles in the Euclidean plane is a well-known topic, but for general normed planes there exists a variety of different concepts. These can be of a special kind, e.g. also preserving special orthogonality types. But these concepts are no angle measures in the sense of measure theory since they are not additive. This motivates us to define a new angle measure for normed planes that is in fact a measure in the sense of measure theory. Furthermore, we look at related types of rotation and reflection.  相似文献   
7.
We analyze isolated resonance curves (IRCs) in single-degree-of-freedom systems possessing nonlinear damping. Through the combination of singularity theory and the averaging method, the onset and merging of IRCs, which coincide to isola and simple bifurcation singularities, respectively, can be analytically predicted. Numerical simulations confirm the accuracy of the analytical developments. Another important finding of this paper is that we unveil a geometrical connection between the topology of the damping force and IRCs. Specifically, we demonstrate that extremas and zeros of the damping force correspond to the appearance and merging of IRCs. Considering a damping force possessing several minima and maxima confirms the general validity of the analytical result. It also evidences a very complex scenario for which different IRCs are created, co-exist and then merge together to form a super IRC which eventually merges with the main resonance peak.  相似文献   
8.
We give the parameter version of a localization theorem for the Bergman metric near the boundary points of strictly pseudoconvex domains. The approximation theorem for square integrable holomorphic functions on such domains in the spirit of Graham-Kerzman is proved in the hereby paper, as well.  相似文献   
9.
10.
The paper presents an interphase cohesive zone model (CZM) incorporating stress multi-axiality devised to capture, by simplified micro-modeling, the influence of the in-plane strain and stress state in the mechanical response of the CZM. Moreover, the model is able to account for the Poisson-related effect in the interphase, which can play an important role in the modeling of heterogeneous masonry elements. From the constitutive point of view, the proposed formulation couples damage and friction by addressing a smooth transition from a quasi-brittle response to a residual frictional behavior described by a Coulomb law with unilateral contact. As in-plane stresses are accounted for, damage activation and evolution are governed by a Drucker–Prager law with linear softening. A predictor-corrector procedure based on a backward Euler scheme is detailed for integrating the nonlinear evolutive problem together with the related tangent operator which consistently linearizes the algorithmic strategy. This framework is embedded into a kinematically-enriched finite element interphase formulation incorporating stress multi-axiality. The modeling features of the resulting numerical tool are tested both at the local level, for the typical interphase point, and in meso-structural tests consisting of brick-mortar triplets, investigating the capability of the proposed model and numerical procedure to simulate the brick-mortar decohesion mechanism during confined slip tests.  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