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   125209篇
  免费   2061篇
  国内免费   567篇
化学   56456篇
晶体学   1114篇
力学   7539篇
综合类   4篇
数学   38738篇
物理学   23986篇
  2023年   342篇
  2022年   465篇
  2021年   811篇
  2020年   836篇
  2019年   835篇
  2018年   11033篇
  2017年   10849篇
  2016年   7616篇
  2015年   2242篇
  2014年   1813篇
  2013年   3328篇
  2012年   6907篇
  2011年   13679篇
  2010年   7607篇
  2009年   7765篇
  2008年   9453篇
  2007年   11470篇
  2006年   2927篇
  2005年   3730篇
  2004年   3521篇
  2003年   3567篇
  2002年   2375篇
  2001年   1295篇
  2000年   1204篇
  1999年   874篇
  1998年   731篇
  1997年   614篇
  1996年   818篇
  1995年   556篇
  1994年   518篇
  1993年   565篇
  1992年   486篇
  1991年   401篇
  1990年   360篇
  1989年   317篇
  1988年   301篇
  1987年   312篇
  1986年   307篇
  1985年   375篇
  1984年   354篇
  1983年   269篇
  1982年   288篇
  1981年   240篇
  1980年   221篇
  1979年   219篇
  1978年   183篇
  1977年   162篇
  1976年   154篇
  1975年   132篇
  1973年   158篇
排序方式: 共有10000条查询结果,搜索用时 32 毫秒
71.
72.
The structure, chemical composition, and magnetic properties of electrochemically deposited nanocrystalline Co-Ni-Fe films were investigated using a number of techniques. A high saturation magnetic induction up to B s = 21 kG was attained. An enhancement of the saturation magnetization compared to the ideal anticipated one was revealed, which correlated with the nonlinear behavior of the structural phase composition and lattice parameters with the change of the composition. The text was submitted by the authors in English.  相似文献   
73.
74.
75.
76.
77.
We prove a general compactness result for the solution set of the compressible Navier–Stokes equations with respect to the variation of the underlying spatial domain. Among various corollaries, we then prove a general existence theorem for the system in question with no restrictions on smoothness of the spatial domain. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
78.
A forecasting model is developed for the number of daily applications for loans at a financial services telephone call centre. The purpose of the forecasts and the associated prediction intervals is to provide effective staffing policies within the call centre. The model building process is constrained by the availability of only 2 years and 7 months of data. The distinctive feature of the data is that demand is driven in the main by advertising. The analysis given focuses on applications stimulated by press advertising. Unlike previous analyses of broadly similar data, where ARIMA models were used, a model with a dynamic level, multiplicative calendar effects and a multiplicative advertising response is developed and shown to be effective.  相似文献   
79.
This paper describes three case studies which investigated issues relating to the implementation and management of advanced information technology. The benefits derived from information technology were found to vary from one organization to another. These studies provide further evidence to support earlier research findings that senior management has an important role to play in the effective exploitation of information technology, and that the investment approach taken by an organization has a significant effect on the development of computer-based information systems. The effectiveness of a system depends not only on applying the appropriate technology, but also on how successfully technical and behavioural issues are resolved.  相似文献   
80.
We show that every composition operator which is an isometry of the Dirichlet space is induced by a univalent full map of the disk into itself that fixes the origin. This is an analogue of the Hardy space result for inner functions due to Nordgren. The proof relies on the Stone-Weierstrass theorem and the Riesz representation theorem.

  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