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   4007篇
  免费   176篇
  国内免费   24篇
化学   2342篇
晶体学   39篇
力学   154篇
数学   923篇
物理学   749篇
  2023年   30篇
  2022年   32篇
  2021年   43篇
  2020年   90篇
  2019年   95篇
  2018年   93篇
  2017年   87篇
  2016年   186篇
  2015年   138篇
  2014年   176篇
  2013年   436篇
  2012年   198篇
  2011年   229篇
  2010年   162篇
  2009年   153篇
  2008年   185篇
  2007年   195篇
  2006年   187篇
  2005年   135篇
  2004年   167篇
  2003年   76篇
  2002年   87篇
  2001年   63篇
  2000年   53篇
  1999年   54篇
  1998年   45篇
  1997年   53篇
  1996年   45篇
  1995年   42篇
  1994年   46篇
  1993年   33篇
  1992年   22篇
  1991年   19篇
  1990年   19篇
  1989年   23篇
  1988年   30篇
  1986年   16篇
  1985年   33篇
  1984年   34篇
  1983年   32篇
  1982年   26篇
  1981年   33篇
  1980年   29篇
  1979年   23篇
  1978年   24篇
  1977年   28篇
  1976年   16篇
  1975年   22篇
  1974年   20篇
  1973年   22篇
排序方式: 共有4207条查询结果,搜索用时 78 毫秒
181.
We introduce the class of restricted k[A]-modules and p t -Jordan types for a finite abelian p-group A of exponent at least p t and a field k of characteristic p. For these modules, we generalize several theorems by Benson, verify a generalization of conjectures stated by Suslin and Rickard giving constraints on Jordan types for modules of constant Jordan type when t is 1. We state conjectures giving constraints on p t -Jordan types and show that many p t -Jordan types are realizable.  相似文献   
182.
183.
184.
185.
186.
Poor bonding strength between nanomaterials and cement composites inevitably lead to the failure of reinforcement. Herein, a novel functionalization method for the fabrication of functionalized graphene oxide (FGO), which is capable of forming highly reliable covalent bonds with cement hydration products, and therefore, suitable for use as an efficient reinforcing agent for cement composites, is discussed. The bonding strength between cement and aggregates was improved more than 21 times with the reinforcement of FGO. The fabricated FGO also demonstrated many important features, including high reliability in cement pastes, good dispersibility, and efficient structural refinement of cement hydration products. With the incorporation of FGO, cement mortar samples demonstrated up to 40 % increased early and ultimate strength. Such results make the fast demolding and manufacture of light constructions become highly possible, and show strong advantages on improving productivity, saving cost, and reducing CO2 emissions in practical applications.  相似文献   
187.
188.
Some growth conditions of the resolvent function of a Banach space operator are investigated using higher order Cesàro means. More precisely, Abel and Nevanlinna estimates are obtained under the condition of boundedness of some weighted Cesàro averages. Also, certains results related to the (strong or uniform) convergence of Cesàro means are mentioned.  相似文献   
189.
In this paper, methods to produce rapid strain rate changes for strain rate sensitivity measurements in Split Hopkinson Bar arrangements are presented and discussed. Two different cases are considered: a strain rate change test within the high strain rate region in compression, and a tension test incorporating a large strain rate jump directly from the low strain rate region to high strain rates. The former method is based on the loading wave amplitude manipulation, while the latter method is based on the incorporation of a low strain rate loading device into a Tensile Split Hopkinson Bar apparatus.  相似文献   
190.
This paper presents a novel mass conservative, positivity preserving wetting and drying treatment for Godunov‐type shallow water models with second‐order bed elevation discretization. The novel method allows to compute water depths equal to machine accuracy without any restrictions on the time step or any threshold that defines whether the finite volume cell is considered to be wet or dry. The resulting scheme is second‐order accurate in space and keeps the C‐property condition at fully flooded area and also at the wet/dry interface. For the time integration, a second‐order accurate Runge–Kutta method is used. The method is tested in two well‐known computational benchmarks for which an analytical solution can be derived, a C‐property benchmark and in an additional example where the experimental results are reproduced. Overall, the presented scheme shows very good agreement with the reference solutions. The method can also be used in the discontinuous Galerkin method. Copyright © 2016 John Wiley & Sons, Ltd.  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