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   534篇
  免费   14篇
  国内免费   1篇
电工技术   4篇
化学工业   64篇
金属工艺   59篇
机械仪表   4篇
建筑科学   17篇
矿业工程   1篇
能源动力   5篇
轻工业   28篇
水利工程   12篇
无线电   40篇
一般工业技术   69篇
冶金工业   212篇
自动化技术   34篇
  2021年   4篇
  2020年   5篇
  2019年   6篇
  2018年   10篇
  2017年   4篇
  2016年   10篇
  2015年   4篇
  2014年   2篇
  2013年   19篇
  2012年   15篇
  2011年   25篇
  2010年   21篇
  2009年   22篇
  2008年   28篇
  2007年   35篇
  2006年   23篇
  2005年   23篇
  2004年   25篇
  2003年   25篇
  2002年   17篇
  2001年   16篇
  2000年   19篇
  1999年   18篇
  1998年   19篇
  1997年   14篇
  1996年   12篇
  1995年   10篇
  1994年   12篇
  1993年   13篇
  1992年   10篇
  1991年   4篇
  1990年   6篇
  1989年   11篇
  1988年   5篇
  1987年   8篇
  1986年   6篇
  1985年   12篇
  1984年   2篇
  1983年   2篇
  1982年   5篇
  1980年   4篇
  1979年   2篇
  1977年   2篇
  1976年   2篇
  1974年   1篇
  1973年   1篇
  1972年   2篇
  1971年   1篇
  1968年   1篇
  1967年   1篇
排序方式: 共有549条查询结果,搜索用时 15 毫秒
1.
2.
N Biswas  R.G Warnock 《Water research》1985,19(8):1065-1071
Soil columns were used as denitrifying reactors in the laboratory where the feed solutions were composed of nitrified solution and kitchen waste. Five different carbon (expressed as methanol) to nitrogen ratios ranging from 2:1 to 6:1 were applied to twenty soil columns. Transformation of nitrogen compounds and fate of associated parameters during denitrification were investigated. A high degree of denitrification was obtained for C:N ratios of 4:1 or higher. Rate of application was not a significant factor in this study. Most of the TKN present in the feed solutions escaped the denitrification reactors. Production of total alkalinity during denitrification was found to be somewhat lower than the values reported in the literature. In some cases the column effluents contained higher solids concentrations than in the influent.  相似文献   
3.
4.
The 2-process theory of semantic priming (J. H. Neely, 1977; M. I. Posner and C. R. Snyder, 1975) was used to determine the maintenance of automatic processes after severe closed head injury (CHI) and to determine whether processes that demand attention suffer a deficit. Ss with severe CHI (N?=?18,?>?2 yrs postinjury) and 18 matched control Ss completed a lexical decision task in which a category prime was followed by a target. Automatic and attentional priming were determined by orthogonally varying prime–target relatedness, expectancy, and stimulus onset asynchrony. Although the CHI Ss had slower reaction times (RTs) overall, there were no significant group differences in the magnitude of either the automatic or attentional component of semantic priming. The present results indicate the integrity of semantic processes and normal semantic priming in long-term patients with severe CHI. The results are discussed in relation to an attentional resource hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
5.
6.
7.
8.
Contends, on the basis of posited social-role theory of gender and helping, that the male gender role fosters helping that is heroic and chivalrous, whereas the female gender role fosters helping that is nurturant and caring. In social psychological studies, helping behavior has mainly been examined in the context of short-term encounters with strangers. This focus has tended to exclude from the research literature those helping behaviors prescribed by the female gender role, because they are displayed primarily in long-term, close relationships. In contrast, the helping behaviors prescribed by the male gender role have been generously represented in research findings because they are displayed in relationships with strangers as well as in close relationships. Results from a meta-analytic review of sex differences in 172 studies (appended) in helping behavior indicate that in general men helped more than women and women received more help than men. Nevertheless, sex differences in helping were inconsistent across studies and were successfully predicted by various attributes of the studies and the helping behaviors. (96 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
9.
Explored projection in group counseling by examining the relationship between the group members' interpersonal problems and their perception of the group leader. Before participation, 118 personal-growth group members filled out the Inventory of Interpersonal Problems by L. M. Horowitz et al (see record 1989-10599-001) and after each session they filled out the Trainer Behavior Scale (L. Bolman, 1971). A latent variable analysis revealed that during the 1st 10 group sessions, overly dominant group members perceived the group leaders as more dominant and overly cold group members perceived the group leaders as less affiliative. There was less relationship between group members' interpersonal problems and ratings for group leaders over time. Implications of these results are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
10.
As larger wind turbines are placed on taller towers, rotors frequently operate in atmospheric conditions that support organized, coherent turbulent structures. It is hypothesized that these structures have a detrimental impact on the blade fatigue life experienced by the wind turbine. These structures are extremely difficult to identify with sophisticated anemometry such as ultrasonic anemometers. This study was performed to identify the vortex characteristics that contribute to high‐amplitude cyclic blade loads, assuming that these vortices exist under certain atmospheric conditions. This study does not attempt to demonstrate the existence of these coherent turbulent structures. In order to ascertain the idealized worst‐case scenario for vortical inflow structures impinging on a wind turbine rotor, we created a simple, analytic vortex model. The Rankine vortex model assumes that the vortex core undergoes solid body rotation to avoid a singularity at the vortex centre and is surrounded by a two‐dimensional potential flow field. Using the wind turbine as a sensor and the FAST wind turbine dynamics code with limited degrees of freedom, we determined the aerodynamic loads imparted to the wind turbine by the vortex structure. We varied the size, strength, rotational direction, plane of rotation, and location of the vortex over a wide range of operating parameters. We identified the vortex conformation with the most significant effect on the blade root bending moment cyclic amplitude. Vortices with radii on the scale of the rotor diameter or smaller caused blade root bending moment cyclic amplitudes that contribute to high damage density. The rotational orientation, clockwise or counter‐clockwise, produces little difference in the bending moment response. Vortices in the XZ plane produce bending moment amplitudes significantly greater than vortices in the YZ plane. Published in 2005 by John Wiley & Sons, Ltd.  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