全文获取类型
收费全文 | 4743篇 |
免费 | 119篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 38篇 |
综合类 | 1篇 |
化学工业 | 1016篇 |
金属工艺 | 58篇 |
机械仪表 | 82篇 |
建筑科学 | 242篇 |
矿业工程 | 21篇 |
能源动力 | 75篇 |
轻工业 | 439篇 |
水利工程 | 39篇 |
石油天然气 | 20篇 |
无线电 | 228篇 |
一般工业技术 | 889篇 |
冶金工业 | 1113篇 |
原子能技术 | 33篇 |
自动化技术 | 572篇 |
出版年
2022年 | 26篇 |
2021年 | 41篇 |
2020年 | 47篇 |
2019年 | 46篇 |
2018年 | 58篇 |
2017年 | 43篇 |
2016年 | 78篇 |
2015年 | 68篇 |
2014年 | 128篇 |
2013年 | 274篇 |
2012年 | 189篇 |
2011年 | 252篇 |
2010年 | 170篇 |
2009年 | 187篇 |
2008年 | 239篇 |
2007年 | 204篇 |
2006年 | 221篇 |
2005年 | 194篇 |
2004年 | 148篇 |
2003年 | 140篇 |
2002年 | 131篇 |
2001年 | 91篇 |
2000年 | 102篇 |
1999年 | 77篇 |
1998年 | 81篇 |
1997年 | 98篇 |
1996年 | 91篇 |
1995年 | 71篇 |
1994年 | 78篇 |
1993年 | 84篇 |
1992年 | 81篇 |
1991年 | 53篇 |
1990年 | 80篇 |
1989年 | 73篇 |
1988年 | 57篇 |
1987年 | 76篇 |
1986年 | 71篇 |
1985年 | 80篇 |
1984年 | 76篇 |
1983年 | 57篇 |
1982年 | 58篇 |
1981年 | 63篇 |
1980年 | 38篇 |
1979年 | 52篇 |
1978年 | 48篇 |
1977年 | 39篇 |
1976年 | 33篇 |
1975年 | 32篇 |
1974年 | 29篇 |
1973年 | 28篇 |
排序方式: 共有4866条查询结果,搜索用时 234 毫秒
11.
The authors highlight several possible ways in which the construction industry could lower present emissions of the greenhouse gas, carbon dioxide. It is an excellent discussion document and is recommended reading. 相似文献
12.
Bond Gary R.; Dietzen Laura L.; McGrew John H.; Miller Larry D. 《Canadian Metallurgical Quarterly》1995,40(2):75
Tested the hypothesis that Ss with severe mental illnesses would achieve better vocational outcomes with an accelerated approach to supported employment (AASE), as compared to gradual approaches (GA) with prevocational training. 86 Ss (mean age 35.1 yrs) with a diagnosis of a serious mental illness, were randomly assigned to either the AASE, or the GA, which included a minimum of 4 mo prevocational training. Data were obtained on indicators of vocational outcomes over 2 yrs, and for a limited number of Ss (n=36), during the 4th yr of inception into the program. Initially, only 5% of Ss preferred prevocational training. After 1 yr, AASE Ss showed better outcomes for a range of indicators, including achievement of competitive employment, duration of employment and mean earnings. During the 4th yr, 59% of these Ss were competitively employed, as compared to only 6% of GA Ss. Rehabilitation is more effective using AASE than GA. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
13.
Packaging engineers need to be able to accurately determine the forces present in the shipping environment in order to protect packaged goods. The purpose of this study was to determine the vertical vibration levels measured in three separate truck-trailer suspension systems; conventional leaf-spring, conventional air-ride and damaged air-ride. The main conclusion reached in this study is that the air-ride suspension when maintained gives lower power density (PD) levels on all road surfaces studied. A damaged air-ride suspension and leaf-spring suspension are very similar in response frequencies, although the damaged air-ride produces higher vibration levels at lower frequencies. 相似文献
14.
15.
A mathematical model was developed to describe the removal of volatile organic compounds from drinking water in aeration basins. The model was used to simulate removal under a range of expected treatment conditions using the Continuous Systems Modeling Program. Results indicated that temperature and air-to-water ratio are the major factors influencing the removal of chloroform from water in an aeration basin. Bubble diameter was a lesser factor while liquid residence time had the smallest effect of the variables examined. 相似文献
16.
GaryFromer 《软件工程师》2003,(10):57-57
<正> 新的一年里,似乎每个人都在谈论中小企业日渐增长的软件需求,而且理由都很充分。今天的中小企业界定十分宽泛,从只有10个员工的公司到年收入5亿美金的企业都可以划归到这个范围里,他们现在可以找到很多专门为他们开发的解决方案,帮助他们改善生产效率、加强销售和合作机会,以及改善客户关系。但是在那些销售人员敲你的门,进来告诉你某个软件解决方案的好处之前,请你一定做好充分的准备。你的选择不仅仅关系到企业内部运营效率的提 相似文献
17.
18.
Collected ratings of communication ease and of engagement for 95 deaf junior and senior high school students (aged 12–21 yrs) in a large, urban, multiethnic school for the deaf. Ratings were made by the students' English teachers and by the students themselves. High teacher ratings for communication ease and engagement were associated with high academic achievement as measured by the Stanford Achievement Test. High student ratings for communication ease were also associated with academic achievement. The 2 best predictors of academic achievement were student-rated communication ease and teacher-rated engagement. Findings suggest that it is important for teachers to be sensitive to the level of communication comfort of their students because students who enjoy easier communication may be more likely to be engaged, or more actively involved, in classroom learning and to demonstrate higher academic achievement. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
19.
Reports a meta-analysis comparing the size of semantic priming effects on young and older adults' lexical decision and pronunciation latency. The analysis included 15 studies with 49 conditions varying the semantic relatedness of a prime stimulus (single word or whole sentence) and a target word. An effect-size analysis on the difference between young and older adults' semantic priming effect (unrelated minus related latency) indicated that semantic priming effects are reliably larger for older than for young adults. There was no evidence for nonhomogeneity in this age difference across the different conditions. The relationship between young and older adults' semantic priming effects was described by a function with a positive intercept and a slope of 1.0. This pattern of findings favors aging models postulating process-specific slowing rather than general cognitive slowing. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
20.
Bruce C. Bunker R. James Kirkpatrick Richard K. Brow Gary L. Turner Carolyn Nelson 《Journal of the American Ceramic Society》1991,74(6):1430-1438