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   26772篇
  免费   687篇
  国内免费   34篇
电工技术   329篇
综合类   14篇
化学工业   5922篇
金属工艺   516篇
机械仪表   464篇
建筑科学   1159篇
矿业工程   332篇
能源动力   650篇
轻工业   1725篇
水利工程   226篇
石油天然气   245篇
无线电   1712篇
一般工业技术   4078篇
冶金工业   6147篇
原子能技术   265篇
自动化技术   3709篇
  2022年   246篇
  2021年   413篇
  2020年   266篇
  2019年   346篇
  2018年   422篇
  2017年   369篇
  2016年   485篇
  2015年   391篇
  2014年   614篇
  2013年   1651篇
  2012年   937篇
  2011年   1201篇
  2010年   922篇
  2009年   971篇
  2008年   1148篇
  2007年   1063篇
  2006年   973篇
  2005年   881篇
  2004年   743篇
  2003年   711篇
  2002年   705篇
  2001年   485篇
  2000年   390篇
  1999年   446篇
  1998年   440篇
  1997年   427篇
  1996年   473篇
  1995年   443篇
  1994年   451篇
  1993年   436篇
  1992年   431篇
  1991年   271篇
  1990年   410篇
  1989年   387篇
  1988年   336篇
  1987年   404篇
  1986年   348篇
  1985年   441篇
  1984年   463篇
  1983年   398篇
  1982年   375篇
  1981年   297篇
  1980年   298篇
  1979年   357篇
  1978年   299篇
  1977年   238篇
  1976年   217篇
  1975年   245篇
  1974年   217篇
  1973年   224篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
31.
Six measures of divergent thinking were administered to 825 men ranging in age from 17 to 101 over the period from 1959 to 1972; repeat administrations were given to a subset of 278 men after a 6-year interval. Cross-sectional analyses showed curvilinear trends, with an increase in scores for men under 40 and a decline thereafter. Repeated measures analyses on subjects initially aged 33 to 74 generally replicated this finding, whereas cross-sequential analyses suggested a decline for all cohorts tested at a later time. Additional analyses suggested that not all of the decline could be attributed to reduced speed of response production. These longitudinal findings confirm earlier cross-sectional reports of decline in divergent thinking abilities with age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
32.
33.
34.
An account of the use of landscape as subject-matter as a basis for the exploration of personal concerns and the search for self by various 20th Century photographers. Particular reference is made to the landscape photography of Eugene Atget, Edward Weston and Bill Brandt.  相似文献   
35.
36.
37.
38.
Utility conservation programmes are designed to benefit both participants and non-participants. This article outlines the issues involved in designing conservation programmes for utilities and determining the appropriate amount of incentives that can be provided to participants without harming non-participants. More importantly, the article discusses the issue of access to the programmes by utility customers. It concludes that it is the existing restrictions to participation, and not the level of compensation, that are of greatest concern to non-participants. A number of utility programmes designed to eliminate the problem of non-participation are reviewed.  相似文献   
39.
In order to obtain a bonded wood product from the tree, wood must be subjected to a series of processes. These include, among others, vital processes like drying of the green wood and machining of the surfaces of the dried wood in preparation for bonding. However, when wood is machined with dull blades, thermal degradation of the wood frequently occurs. The effects of kiln drying and thermal degradation of wood on the performance of the adhesive joints subsequently formed from such wood were investigated. Tapered double cantilever beam (TDCB) test specimens obtained from hard maple and phenol–resorcinol–formaldehyde (PRF) adhesives were used in the investigations. The enhancement of fracture energy due to the reduction in the moisture content of wood, the improved performance of adhesive joints due to rejointing of wood surfaces before bonding, and the reduction of adhesive joint strength resulting from thermal degradation of wood are presented and discussed.  相似文献   
40.
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