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   15515篇
  免费   935篇
  国内免费   28篇
电工技术   167篇
综合类   43篇
化学工业   3265篇
金属工艺   307篇
机械仪表   317篇
建筑科学   690篇
矿业工程   45篇
能源动力   508篇
轻工业   1260篇
水利工程   124篇
石油天然气   51篇
无线电   1118篇
一般工业技术   3040篇
冶金工业   2278篇
原子能技术   119篇
自动化技术   3146篇
  2023年   146篇
  2022年   287篇
  2021年   571篇
  2020年   377篇
  2019年   382篇
  2018年   496篇
  2017年   461篇
  2016年   531篇
  2015年   465篇
  2014年   594篇
  2013年   1074篇
  2012年   980篇
  2011年   1167篇
  2010年   813篇
  2009年   755篇
  2008年   799篇
  2007年   786篇
  2006年   587篇
  2005年   513篇
  2004年   380篇
  2003年   391篇
  2002年   344篇
  2001年   218篇
  2000年   190篇
  1999年   211篇
  1998年   225篇
  1997年   199篇
  1996年   192篇
  1995年   184篇
  1994年   158篇
  1993年   150篇
  1992年   119篇
  1991年   75篇
  1990年   124篇
  1989年   117篇
  1988年   81篇
  1987年   93篇
  1986年   106篇
  1985年   101篇
  1984年   90篇
  1983年   79篇
  1982年   96篇
  1981年   90篇
  1980年   71篇
  1979年   70篇
  1978年   64篇
  1977年   76篇
  1976年   63篇
  1975年   45篇
  1974年   43篇
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
111.
Trichloroethylene (TCE) is a common contaminant of underground water supplies. To examine the effect of TCE on the developing central nervous system, rats were exposed to TCE throughout gestation until 21 days postpartum via their dams' drinking water. TCE concentrations of 312 mg/l, 625 mg/l and 1250 mg/l were tested. Exploratory behavior was higher in 60- and 90-day old male rats which were exposed to any level of TCE. The effect of TCE-exposure on locomotor activity (running wheel) was also examined in 60-day old males (625 and 1250 ppm exposure groups). Locomotor activity was significantly higher in rats exposed to 1250 ppm TCE. These data suggest that TCE has long-term effects on behaviour.  相似文献   
112.
Examined the judgments made by 384 undergraduates and 384 50–74 yr olds of assailant and victim responsibility for a sexual assault. Ss were assigned to 1 of 3 conditions: they viewed slides of an assault, read a passage about the crime, or read the passage and saw photographs of both the assailant and the victim. The rapist was presented as either a well-dressed or poorly dressed young man, and the victim appeared either as a provocative or demure young woman. Ss also learned that the victim either physically resisted or failed to resist the assailant. Young Ss attributed more responsibility to the assailant than did older Ss, and the provocative woman was perceived as more responsible for the victimization than the demure woman. Young Ss attributed greater responsibility to the victim when she resisted the assault of a well-dressed assailant than when she resisted a poorly dressed assailant. Females attributed less responsibility to the demure woman when she was assaulted by a poorly dressed assailant than a well dressed assailant. In contrast to older Ss, young Ss who visually observed the crime held the victim more responsible for her victimization. Results are interpreted in terms of the defensive attribution hypothesis of E. Walster (see record 1966-02829-001) and the discounting principle of attribution presented by H. H. Kelley (see record 1973-24800-001). (French abstract) (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
113.
Memorializes E. E. Jones, whose early development of attribution theory, the actor–observer effect, and the correspondence bias as well as later work on self-handicapping, social stigma, and strategic self-presentation are central to modern social psychology. He built graduate programs at Duke and Princeton, trained many influential social psychologists, and received virtually every award in his field. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
114.
Infants were presented with a moving object under 2 lighting conditions to investigate the role of vision in early reaching. The motion of the target object also allowed for an analysis of the infants' ability to use a predictive style of reaching. Infants were tested twice, at 5 and 7.5 months of age, with a moving object in the light and the same object painted with luminescent paint in the dark. Infants successfully contacted the glowing object on about half of their attempts at both ages, although 7.5 month-olds reached more often. Infants also took into account the motion of the target object by aiming their reaches ahead of the object and by reaching with their contralateral hand. These results suggest that proprioceptive feedback and sight of the target allow for successful reaching with limited visual information, even in relatively complex reaching tasks. The infants' success also demonstrates their ability to adapt their movements and reaching strategy to the speed and trajectory of the target object in order to reach predictively. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
115.
The dislocation structures of bulk textured and epitaxial thin film YBa2Cu3O7 superconductors are examined. Correlations between increases in flux pinning and dislocation densities are noted. A model for flux pinning by individual dislocations is presented. This gives a treatment of strain induced effects and effects of normal state region interactions. It is shown that the values of pinning predicted are in line with experimental observations.  相似文献   
116.
Marital discord and depressive symptomatology have repeatedly been found to be associated, but little is known about variables that influence this relationship. Data were collected from 139 couples seeking marital therapy, and analyses were conducted separately by gender. For wives, lower problem-solving ability, physical aggression by the partner, and 1 relationship belief predicted depressive symptomatology after the variance due to marital discord was removed in regression analyses. In addition to these predictors, less spouse-specific assertiveness, unemployment, and 1 other relationship belief were associated with depressive symptomatology for women after the variance due to marital discord was removed in partial correlation analyses. For men, only lower problem-solving ability added to the prediction of depressive symptomatology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
117.
This paper proposes a high‐performance connection management architecture to design a common QoS framework applied to an ATM network based on the Open Distributed Processing (ODP) concept. We design the QoS framework in accordance from the RM‐ODP information and computational viewpoints. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   
118.
119.
In a study of how aviation expertise influences age differences in narrative processing, young and older pilots and nonpilots read and recalled aviation and general narratives. They chose referents for sentences referring to a protagonist or minor character mentioned 1 sentence (recent character) or 3 sentences (distant character) before this target sentence. All groups chose referents less accurately for sentences about distant and minor characters than about recent and protagonist characters, perhaps because these referents were less likely to be in working memory. Young readers and pilots were more accurate for distant and minor character target sentences in aviation narratives and recalled aviation narratives more accurately. Expertise did not reduce age differences. Expertise differences may reflect decreased demands on working memory capacity, and age declines may reflect reduced capacity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
120.
A systematic approach for the design of weakly coupled thermoelastoplastic systems is presented. The Newton–Raphson iteration method is used in the solution process so that analytic design sensitivity formulations may be efficiently derived via the direct differentiation technique. The derived formulations are suitable for finite element implementations. Analysis and sensitivity analysis capabilities are combined with numerical optimization to form an optimum design algorithm. To demonstrate the algorithm, we optimally design a weldment with respect to manufacturing and service life aspects.  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