全文获取类型
收费全文 | 26808篇 |
免费 | 688篇 |
国内免费 | 34篇 |
专业分类
电工技术 | 329篇 |
综合类 | 14篇 |
化学工业 | 5926篇 |
金属工艺 | 516篇 |
机械仪表 | 464篇 |
建筑科学 | 1160篇 |
矿业工程 | 332篇 |
能源动力 | 652篇 |
轻工业 | 1725篇 |
水利工程 | 226篇 |
石油天然气 | 245篇 |
无线电 | 1714篇 |
一般工业技术 | 4086篇 |
冶金工业 | 6166篇 |
原子能技术 | 265篇 |
自动化技术 | 3710篇 |
出版年
2022年 | 246篇 |
2021年 | 413篇 |
2020年 | 266篇 |
2019年 | 347篇 |
2018年 | 422篇 |
2017年 | 369篇 |
2016年 | 487篇 |
2015年 | 391篇 |
2014年 | 614篇 |
2013年 | 1652篇 |
2012年 | 937篇 |
2011年 | 1201篇 |
2010年 | 922篇 |
2009年 | 971篇 |
2008年 | 1149篇 |
2007年 | 1066篇 |
2006年 | 973篇 |
2005年 | 883篇 |
2004年 | 744篇 |
2003年 | 712篇 |
2002年 | 705篇 |
2001年 | 485篇 |
2000年 | 391篇 |
1999年 | 447篇 |
1998年 | 443篇 |
1997年 | 430篇 |
1996年 | 476篇 |
1995年 | 443篇 |
1994年 | 452篇 |
1993年 | 440篇 |
1992年 | 432篇 |
1991年 | 271篇 |
1990年 | 411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 | 240篇 |
1976年 | 219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 15 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.
Robert Greetham 《Landscape Research》1992,17(1):10-19
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.
Robert M. Wirtshafter 《Energy Policy》1985,13(2):143-155
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.