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   370131篇
  免费   4282篇
  国内免费   1435篇
化学   192493篇
晶体学   5982篇
力学   17277篇
综合类   8篇
数学   41571篇
物理学   118517篇
  2020年   2744篇
  2019年   2984篇
  2018年   3678篇
  2017年   3621篇
  2016年   5869篇
  2015年   3979篇
  2014年   6036篇
  2013年   16407篇
  2012年   12641篇
  2011年   15855篇
  2010年   10658篇
  2009年   10743篇
  2008年   14571篇
  2007年   14512篇
  2006年   13889篇
  2005年   12654篇
  2004年   11628篇
  2003年   10125篇
  2002年   10038篇
  2001年   11658篇
  2000年   8907篇
  1999年   6931篇
  1998年   5625篇
  1997年   5553篇
  1996年   5342篇
  1995年   4863篇
  1994年   4683篇
  1993年   4675篇
  1992年   5017篇
  1991年   5143篇
  1990年   4680篇
  1989年   4646篇
  1988年   4686篇
  1987年   4516篇
  1986年   4278篇
  1985年   6017篇
  1984年   6161篇
  1983年   5017篇
  1982年   5357篇
  1981年   5160篇
  1980年   5001篇
  1979年   5105篇
  1978年   5215篇
  1977年   5135篇
  1976年   5199篇
  1975年   4873篇
  1974年   4840篇
  1973年   4951篇
  1972年   3282篇
  1971年   2566篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Journal of Solid State Electrochemistry - The “shuttle effect” of polysulfides is a serious issue, resulting in a decrease in the life-cycle of lithium-sulfur (Li-S) batteries. To...  相似文献   
62.
Journal of Thermal Analysis and Calorimetry - In recent decades, the growth of heat transfer using nanomaterials in the conventional base fluid has caught the attention of researchers...  相似文献   
63.
64.
65.
66.
67.
68.
Injection-moulding is one of the most common manufacturing processes used for polymers. In many applications, the mechanical properties of the product is of great importance. Injection-moulding of thin-walled polymer products tends to leave the polymer structure in a state where the mechanical properties are anisotropic, due to alignment of polymer chains along the melt flow direction. The anisotropic elastic-viscoplastic properties of low-density polyethylene, that has undergone an injection-moulding process, are therefore examined in the present work. Test specimens were punched out from injection-moulded plates and tested in uniaxial tension. Three in-plane material directions were investigated. Because of the small thickness of the plates, only the in-plane properties could be determined. Tensile tests with both monotonic and cyclic loading were performed, and the local strains on the surface of the test specimens were measured using image analysis. True stress vs. true strain diagrams were constructed, and the material response was evaluated using an elastic-viscoplasticity law. The components of the anisotropic compliance matrix were determined together with the direction-specific plastic hardening parameters.  相似文献   
69.
Erosion and sediments transport processes have a great impact on industrial structures and on water quality. Despite its limitations, the Saint‐Venant‐Exner system is still (and for sure for some years) widely used in industrial codes to model the bedload sediment transport. In practice, its numerical resolution is mostly handled by a splitting technique that allows a weak coupling between hydraulic and morphodynamic distinct softwares but may suffer from important stability issues. In recent works, many authors proposed alternative methods based on a strong coupling that cure this problem but are not so trivial to implement in an industrial context. In this work, we then pursue 2 objectives. First, we propose a very simple scheme based on an approximate Riemann solver, respecting the strong coupling framework, and we demonstrate its stability and accuracy through a number of numerical test cases. However, second, we reinterpret our scheme as a splitting technique and we extend the purpose to propose what should be the minimal coupling that ensures the stability of the global numerical process in industrial codes, at least, when dealing with collocated finite volume method. The resulting splitting method is, up to our knowledge, the only one for which stability properties are fully demonstrated.  相似文献   
70.
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