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   385篇
  免费   14篇
电工技术   4篇
化学工业   37篇
金属工艺   3篇
机械仪表   5篇
建筑科学   33篇
矿业工程   1篇
能源动力   11篇
轻工业   46篇
水利工程   4篇
无线电   15篇
一般工业技术   33篇
冶金工业   166篇
原子能技术   1篇
自动化技术   40篇
  2023年   2篇
  2022年   1篇
  2021年   9篇
  2020年   3篇
  2019年   3篇
  2018年   6篇
  2017年   6篇
  2016年   14篇
  2015年   1篇
  2014年   5篇
  2013年   28篇
  2012年   23篇
  2011年   27篇
  2010年   13篇
  2009年   19篇
  2008年   14篇
  2007年   14篇
  2006年   9篇
  2005年   16篇
  2004年   13篇
  2003年   19篇
  2002年   3篇
  2001年   13篇
  2000年   10篇
  1999年   9篇
  1998年   17篇
  1997年   9篇
  1996年   10篇
  1995年   9篇
  1994年   6篇
  1993年   11篇
  1992年   2篇
  1991年   1篇
  1990年   5篇
  1989年   4篇
  1987年   4篇
  1986年   7篇
  1985年   1篇
  1984年   7篇
  1983年   4篇
  1982年   4篇
  1981年   4篇
  1980年   3篇
  1978年   1篇
  1977年   3篇
  1976年   3篇
  1975年   2篇
  1973年   1篇
  1972年   1篇
排序方式: 共有399条查询结果,搜索用时 15 毫秒
1.
2.
Birds' use of landmarks to identify spatial locations was examined. Black-capped chickadees (Parus atricapillus) and pigeons (Columba livia) searched for hidden food on a 120-cm–2 tray. In each task the target was near an edge with a nearby landmark. On occasional unrewarded tests the landmark was either left in its usual position, shifted parallel to the edge, shifted perpendicular to the edge, or shifted diagonally. On diagonal landmark shifts the birds shifted their searching more in the parallel direction than in the perpendicular, which violates the predictions of the vector sum model (K. Cheng, 1989). In some cases the birds maintained their searching at a constant perpendicular distance under all landmark shifts. This suggests that perpendicular distance to an edge forms an element in determining where to search on the basis of landmarks. Chickadees and pigeons performed similarly, which suggests similarity in the way they encode locations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
3.
The recent growth in the use of digital radio is reviewed. The technology used to implement low-power digital radio in the local exchange loop plant is discussed. The integration of digital radio subscriber loops withnetwork intelligence is explored. The relationship between low-power digital radio loops and broadband fiber loops is briefly examined, and standards and frequency allocation activities are summarized  相似文献   
4.
Working collaboratively, psychologist educators and trainers at the doctoral, internship, and postdoctoral levels; credentialers; practitioners; and students offer 8 proposals for psychologists to consider in recognizing, assessing, and intervening with problems of professional competence in students and practicing professionals. In the proposals, the authors address the following topics: definitions and categories; preparing the system; self-assessment; remediation; diversity; communication across various levels of the system; confidentiality; and ethical, regulatory, and legal underpinnings. They also propose future directions for the assessment of problems in professional competence in both students and practicing psychologists. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
5.
6.
A simple relationship between parameters derived from a13C NMR isotopomer analysis and O2 consumption is presented that allows measurement of the absolute rate of acetyl-CoA oxidation and anaplerotic flux in tissues oxidizing a mixture of four substrates. The method was first applied in a study of the effects of work state and -adrenergic stimulation on net acetate oxidation and anaplerosis in the isolated working rat heart. The results demonstrate that the anticipated ratio of 2 between O2 consumption and TCA cycle flux for hearts oxidizing only acetate holds at low workload when anaplerosis is low, but deviates toward a factor of 3 under high workload conditions when anaplerosis is increased. This analysis was also extended to hearts that oxidize a more physiological mixture of substrates including long-chain fatty acids, acetoacetate, lactate, pyruvate, and glucose. We show that the contribution each substrate makes to total TCA cycle flux can be determined by combined13C NMR and O2 consumption measurements. The present study also demonstrates that stimulation of anaplerosis (by addition of propionate) can significantly alter the relative contribution each substrate makes to total TCA cycle flux. We conclude that if13C labeling patterns are selected appropriately, a comprehensive picture of flux through all major metabolic pathways feeding the cycle can be determined in a single experiment even when complex physiological mixtures of substrates are provided.  相似文献   
7.
8.
The authors tested whether adherence to simultaneous health behavior changes was unitary or domain specific among 76 women who modified smoking, eating, and physical activity to accomplish smoking cessation plus weight control. Random-effects regression analyses showed that adherence to both smoking and diet plans declined linearly and covaried positively; their association tended to grow stronger over time. In contrast, physical activity plan adherence did not change over time and was unrelated to other domains. At the end of treatment, 65%, 30.5%, and 25% adhered well or excellently to smoking, diet, and activity treatments, respectively. Findings support both unitary and domain-specific aspects of adherence and suggest that among smokers, smoking and eating behaviors may have similarities unshared by physical activity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
9.
This study investigated whether exposure to musical mood induction procedures (MMIP) differentially increases the strength of specific alcohol expectancies for coping motivated (CM) versus enhancement motivated (EM) drinkers. Participants were 86 undergraduates who had elevated scores on either the CM or EM subscale of the Drinking Motives Questionnaire (M. L. Cooper, 1994). Participants were randomly assigned to either a positive or negative mood condition. The Alcohol Craving Questionnaire (E. G. Singleton, S. T. Tiffany, & J. E. Henningfield, 1994) was administered at baseline and after MMIP to assess phasic changes in alcohol expectancy strength. Consistent with hypotheses, only CM drinkers in the negative mood condition reported increased relief expectancies, and only EM drinkers in the positive mood condition reported increased reward expectancies. Theoretical and clinical implications are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
10.
About 10% of the world has access to information and communication technologies (ICTs). Telecenters and cyber cafés are one prevalent way to increase access. This paper suggests increasing access through currently existing, local businesses where people already gather and where proprietors already posses existing business relationships with suppliers and customers. This paper questions the prevailing emphasis on the “cyber'' characteristics of access, e.g., computing and internet access as is currently known, and attempts to refocus the conversation by considering computing and access in the context of the “café,” e.g., as public life in the sense of Habermas, which permits an in situ evolution of relevant access. This analysis is based on extant literature and direct ethnographic research in several public places in six countries. We offer example design perspectives based on a reflection of “third places” as inspiration for appropriate innovation in the provision of computing and communications. © 2005 Wiley Periodicals, Inc.  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