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   4702篇
  免费   54篇
  国内免费   1篇
电工技术   83篇
综合类   1篇
化学工业   404篇
金属工艺   20篇
机械仪表   38篇
建筑科学   45篇
矿业工程   2篇
能源动力   25篇
轻工业   105篇
水利工程   9篇
石油天然气   5篇
无线电   326篇
一般工业技术   387篇
冶金工业   2677篇
原子能技术   29篇
自动化技术   601篇
  2021年   26篇
  2020年   18篇
  2019年   26篇
  2018年   26篇
  2017年   30篇
  2016年   17篇
  2015年   27篇
  2014年   45篇
  2013年   132篇
  2012年   63篇
  2011年   89篇
  2010年   95篇
  2009年   85篇
  2008年   93篇
  2007年   71篇
  2006年   81篇
  2005年   69篇
  2004年   47篇
  2003年   74篇
  2002年   76篇
  2001年   67篇
  2000年   56篇
  1999年   136篇
  1998年   697篇
  1997年   407篇
  1996年   271篇
  1995年   200篇
  1994年   172篇
  1993年   180篇
  1992年   70篇
  1991年   69篇
  1990年   85篇
  1989年   70篇
  1988年   70篇
  1987年   53篇
  1986年   72篇
  1985年   72篇
  1984年   40篇
  1983年   52篇
  1982年   49篇
  1981年   55篇
  1980年   48篇
  1979年   30篇
  1978年   39篇
  1977年   88篇
  1976年   190篇
  1975年   25篇
  1974年   30篇
  1972年   20篇
  1970年   17篇
排序方式: 共有4757条查询结果,搜索用时 15 毫秒
41.
Four experiments were conducted to identify the locus of interference observed during the preparation of bimanual reaching movements. Target locations were specified by color, and the right-hand and left-hand targets could be either the same or a different color. Movements of different amplitudes (Experiment 1) or different directions (Experiment 2) to targets of the same color were initiated more quickly than symmetric movements to targets of different colors. These results indicate that costs observed during bimanual movements arise during target selection rather than during motor programming. Experiments 3 and 4 further examined the interference associated with target selection. Reaction time costs were found with unimanual movements when the target was presented among distractors associated with responses for the other hand. Interference observed during bimanual reaching appears to reflect difficulty in segregating the response rules assigned to each hand. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
42.
43.
Examined psychosocial variables by comparing 10 13–17 yr old adolescents (and their mothers) who had refused cancer treatment with a group of 10 consenting adolescents who were matched on age and demographic and illness variables. Adolescents completed the State-Trait Anxiety Inventory for Children and measures of family characteristics, locus of control, religion, hopelessness, impact of event, and satisfaction with physician. Mothers completed the State-Trait Anxiety Inventory and measures of coping and religion. Adolescent refusers scored lower on state anxiety and subjective distress but scored higher on trait anxiety, religiosity, and external locus of control. Their mothers also scored higher than did the consenting-group mothers on religiosity and trait anxiety. It is suggested that refusers are prone to anxiety and cope with their present distress by maintaining the belief that their lives are determined by fate or religious convictions. An intervention approach that fosters mastery over the cancer experience is advocated. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
44.
45.
46.
A systematic study of wall effects on the shear viscosity of short glass fiber-filled polypropylene and polystyrene is presented. The dependence of these effects on capillary radius, shear rate, temperature, and polymer matrix is examined. The “true” viscosity curves of these materials (free from wall effects) can be obtained by an extrapolation procedure. Breakage of glass fibers in the high shear-rate processes of extrusion and injection molding lead to an appreciable reduction of the viscosity of these materials and is probably the more important effect to take into account in these processes.  相似文献   
47.
48.
We were concerned with the effects of item repetition, list length, and class of item on free recall in elderly as compared with young adults. In Experiment 1, samples of young and elderly adults recalled a list of 27 words and a list of 27 action events (minitasks performed by the subjects). Some items were presented once and some twice. Although the younger subjects showed better recall on both types of lists, the older sample benefited from item repetition as much as did the younger sample. This finding was replicated in Experiment 2. A second finding in Experiment 2 was a significant aging effect in the recall of long but not of short lists of both words and action events. The absence of an Age?×?Repetition Effect interaction was ascribed to the strength nature of the repetition manipulation. The age effects in the recall of the long lists were attributed to possible deficits in retrieval proficiency. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
49.
Four intervention models that aim to reduce problematic caregiver–infant relationships are reviewed within the context of attachment theory. These models include support, guidance, psychotherapy, and infant-led psychotherapy. All of the models are consistent with attachment theory in that they aim to enhance maternal sensitivity and responsiveness. Only infant-led psychotherapy focuses primarily on the mother–infant relationship and directly includes the infant in treatment instead of focusing and working primarily with the more verbal partner, the caregiver. Thus, of the 4 interventions, infant-led psychotherapy is most consistent with the current empirical and theoretical understanding of infants as active contributors to their relationships and development. However, there is little empirical research on this intervention; the bulk of studies evaluate support and guidance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
50.
Add-drop filters are demonstrated using silica-on-silicon optical waveguide technology. This device consists of a full directional coupler subdivided by Mach-Zehnder sections. Tapering of the coupling coefficients is experimentally shown to dramatically reduce the filters' sidelobes. Only one photolithographic step is required using the silica planar waveguide technology, yielding accurate wavelength control of the filters. Excellent agreement between measurement and design was achieved  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