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   2876篇
  免费   97篇
  国内免费   3篇
电工技术   38篇
综合类   1篇
化学工业   484篇
金属工艺   35篇
机械仪表   55篇
建筑科学   174篇
矿业工程   7篇
能源动力   74篇
轻工业   238篇
水利工程   23篇
石油天然气   14篇
无线电   190篇
一般工业技术   439篇
冶金工业   787篇
原子能技术   23篇
自动化技术   394篇
  2023年   12篇
  2022年   18篇
  2021年   30篇
  2020年   33篇
  2019年   40篇
  2018年   54篇
  2017年   46篇
  2016年   52篇
  2015年   37篇
  2014年   54篇
  2013年   141篇
  2012年   117篇
  2011年   171篇
  2010年   107篇
  2009年   116篇
  2008年   142篇
  2007年   146篇
  2006年   116篇
  2005年   123篇
  2004年   102篇
  2003年   84篇
  2002年   85篇
  2001年   62篇
  2000年   48篇
  1999年   60篇
  1998年   130篇
  1997年   78篇
  1996年   67篇
  1995年   49篇
  1994年   45篇
  1993年   34篇
  1992年   41篇
  1991年   32篇
  1990年   29篇
  1989年   36篇
  1988年   26篇
  1987年   36篇
  1986年   26篇
  1985年   25篇
  1984年   28篇
  1983年   27篇
  1982年   15篇
  1981年   20篇
  1980年   22篇
  1979年   20篇
  1978年   22篇
  1977年   15篇
  1976年   42篇
  1975年   20篇
  1973年   16篇
排序方式: 共有2976条查询结果,搜索用时 0 毫秒
81.
82.
The purpose of this study was to investigate the influence of exposure to others’ drink driving during adolescence on self-reported driving under the influence (DUI) of alcohol in young adulthood. Data were drawn from 1956 participants with a driving license enrolled in the International Youth Development Study from Victoria, Australia. During 2003 and 2004, adolescents in Grades 7, 9 and 10 (aged 12–17) completed questionnaires examining whether they had ridden in a vehicle with a driver who had been drinking, as well as other demographic, individual, peer and family risk factors for DUI. In 2010, the same participants (aged 18–24) then reported on their own DUI behaviour. 18% of young adults with a driving license reported DUI in the past 12 months. Exposure to others’ drink driving during adolescence was associated with an increased likelihood of DUI as a young adult (OR = 2.13, 95% CI 1.68–2.69). This association remained after accounting for the effects of other potential confounding factors from the individual, peer and family domains (OR = 1.62, 95% CI 1.23–2.13). Observing the drink driving behaviours of others during adolescence may increase the likelihood of DUI as a young adult. Strategies to reduce youth exposure to drink driving are warranted.  相似文献   
83.
This paper evaluates the performance of 1,346 homes in Alachua County, Florida that were Home Energy Rating System (HERS)-rated between February 1998 and December 2009 for participation in various energy-efficiency programs for new residential construction. The primary analysis objective is to measure the energy-efficiency performance of these HERS-rated homes against conventionally built homes using metered energy consumption data for calendar years 2000–2010. A secondary objective is to assess performance of the four major builders of HERS-rated homes. In calendar year 2000, average energy savings for all HERS-rated homes was 18 %. However, over the following decade average savings degraded steadily, stabilizing around 7 % in the last 5 years of the analysis. We conclude that, while HERS-rated homes in the study area are performing better than similar conventionally built homes, the average HERS-rated home is not achieving the level of savings anticipated based on its HERS score and related energy-efficiency program participation. Differences in savings among builders of HERS-rated homes suggest that variations in program implementation and construction practices can yield significantly different energy performance results. Of the four builders tested, the least efficient averaged 3 % less energy consumed than conventionally built homes, while the most efficient averaged 21 % less. Overall, findings of this study indicate the need for re-examination of the HERS-rating process as a primary benchmark and for increased emphasis on direct measurement and verification of performance using historical energy consumption data.  相似文献   
84.
85.
86.
87.
Stainless steel pipes with different degrees of rouging and a Teflon®-coated rupture disc with severe corrosion were thoroughly investigated by combining multiple surface analytical techniques. The surface roughness and iron oxide layer thickness increase with increasing rouge severity, and the chromium oxide layer coexists with the iron oxide layer in samples with various degrees of rouging. Unlike the rouging observed for stainless steel pipes, the fast degradation of the rupture disc was caused by a crevice corrosion environment created by perforations in the protective Teflon coating. This failure analysis clearly shows the highly corrosive nature of ultrapure water used in the manufacture of pharmaceutical products, and demonstrates some of the unexpected corrosion mechanisms that can be encountered in these environments.  相似文献   
88.
Wheat (Triticum aestivum L.) plays a central role in the health and nutrition of humans. Yet, little is known about possible flavor differences among different varieties. We have developed a model system using the house mouse (Mus musculus L.) to determine feeding preferences as a prelude to extending results to human sensory analysis. Here, we examine the application of a single‐elimination tournament design to the analysis of consumption preferences of a set of hard red and hard white spring wheat varieties. A single‐elimination tournament design in this case pairs 2 wheat varieties and only 1 of the 2 is advanced to further tests. Preferred varieties were advanced until an overall “winner” was identified; conversely, less desirable varieties were advanced such that an overall “loser” was identified. Hollis and IDO702 were the winner and loser, respectively, for the hard red varieties, and Clear White 515 and WA8123 were the winner and loser, respectively, for the hard white varieties. When using the more powerful protocol of 14 mice and a 4?d trial, differences in mean daily consumption preferences of 2 varieties were separated at P‐values as small as 2 × 10?8. The single‐elimination tournament design is an efficient means of identifying the most and least desirable varieties among a larger set of samples. One application for identifying the 2 extremes in preference within a group of varieties would be to use them as parents of a population to identify quantitative trait loci for preference.  相似文献   
89.
90.
Religious people tend to live slightly longer lives (M. E. McCullough, W. T. Hoyt, D. B. Larson, H. G. Koenig, & C. E. Thoresen, 2000). On the basis of the principle of social investment (J. Lodi-Smith & B. W. Roberts, 2007), the authors sought to clarify this phenomenon with a study of religion and longevity that (a) incorporated measures of psychological religious commitment; (b) considered religious change over the life course; and (c) examined 19 measures of personality traits, social ties, health behaviors, and mental and physical health that might help to explain the religion–longevity association. Discrete-time survival growth mixture models revealed that women (but not men) with the lowest degrees of religiousness through adulthood had shorter lives than did women who were more religious. Survival differences were largely attributable to cross-sectional and prospective between-class differences in personality traits, social ties, health behaviors, and mental and physical health. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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