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   264篇
  免费   22篇
化学工业   111篇
金属工艺   2篇
机械仪表   3篇
建筑科学   7篇
能源动力   6篇
轻工业   30篇
水利工程   1篇
石油天然气   1篇
无线电   17篇
一般工业技术   38篇
冶金工业   33篇
原子能技术   1篇
自动化技术   36篇
  2023年   8篇
  2022年   27篇
  2021年   26篇
  2020年   16篇
  2019年   10篇
  2018年   7篇
  2017年   8篇
  2016年   11篇
  2015年   6篇
  2014年   9篇
  2013年   18篇
  2012年   19篇
  2011年   18篇
  2010年   14篇
  2009年   12篇
  2008年   12篇
  2007年   5篇
  2006年   9篇
  2005年   2篇
  2004年   7篇
  2003年   4篇
  2002年   8篇
  1999年   1篇
  1998年   1篇
  1997年   2篇
  1996年   2篇
  1994年   3篇
  1993年   2篇
  1992年   1篇
  1990年   1篇
  1989年   4篇
  1987年   2篇
  1986年   3篇
  1985年   1篇
  1984年   2篇
  1983年   1篇
  1982年   1篇
  1980年   1篇
  1978年   1篇
  1977年   1篇
排序方式: 共有286条查询结果,搜索用时 15 毫秒
51.
We study the temporal evolution of the structure of the world''s largest subway networks in an exploratory manner. We show that, remarkably, all these networks converge to a shape that shares similar generic features despite their geographical and economic differences. This limiting shape is made of a core with branches radiating from it. For most of these networks, the average degree of a node (station) within the core has a value of order 2.5 and the proportion of k = 2 nodes in the core is larger than 60 per cent. The number of branches scales roughly as the square root of the number of stations, the current proportion of branches represents about half of the total number of stations, and the average diameter of branches is about twice the average radial extension of the core. Spatial measures such as the number of stations at a given distance to the barycentre display a first regime which grows as r2 followed by another regime with different exponents, and eventually saturates. These results—difficult to interpret in the framework of fractal geometry—confirm and yield a natural explanation in the geometric picture of this core and their branches: the first regime corresponds to a uniform core, while the second regime is controlled by the interstation spacing on branches. The apparent convergence towards a unique network shape in the temporal limit suggests the existence of dominant, universal mechanisms governing the evolution of these structures.  相似文献   
52.
53.
54.
Parents (N?=?124) who had lost an infant to sudden infant death syndrome were interviewed 3 wks and 18 mo postloss. Two components of religion (religious participation and religious importance) were assessed, and their relations with 3 coping-process variables (perceived social support, cognitive processing of the loss, and finding meaning in the death) were examined. Greater religious participation was related to increased perception of social support and greater meaning found in the loss. Importance of religion was positively related to cognitive processing and finding meaning in the death. Furthermore, through these coping-process variables, religious participation and importance were indirectly related to greater well-being and less distress among parents 18 mo after their infants' deaths. Results suggest that further study of the social and cognitive aspects of religion would be profitable. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
55.
Presents an obituary for Philip Brickman, whose distinguished career in social psychology focused on issues such as justice, happiness, pain, inequality, helping, and coping. From 1968 to 1978, he was a faculty member in the psychology department at Northwestern University. In 1979, he went to the University of Michigan, where he joined the faculty as professor in the Psychology Department and director of the Research Center for Group Dynamics at the Institute for Social Research. By the time of his death, Brickman had published over 50 articles and book chapters, many of them very well known and widely cited. In addition to his published work, he enriched the field through his participation in several professional societies. He had served on the Council of APA's Division 9 (The Society for the Psychological Study of Social Issues; SPSSI) and on the Executive Committee of Division 8 (Personality and Social Psychology), where he provided valuable leadership during the crisis in research funding that occurred during the early years of the first Reagan administration. Brickman passed away in 1982. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
56.
Contrary to unidimensional conceptions of optimism and pessimism, factor analysis of 2 widely used instruments revealed that optimism and pessimism are empirically differentiable, but related, constructs. Moreover, consistent with expectations, optimism and pessimism were differentially linked with fundamental dimensions of mood and personality. Pessimism was principally associated with neuroticism and negative affect. Optimism was primarily associated with extraversion an positive affect. Findings are discussed with reference to current conceptual and measurement models of optimism and pessimism and their relations to broad dimensions of mood and personality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
57.
The "waist" area and external subnuclei of the parabrachial nucleus (PBN) have been implicated in the processing of gustatory information, yet their behavioral roles are not clearly defined. In the current study, areas within and surrounding the PBN were stimulated while oromotor behaviors were monitored in conscious rats. Electrical and chemical (100 mM glutamate) stimulation of the waist area increased ingestive oromotor behaviors over baseline (p  相似文献   
58.
59.
In this work, flexible ferroelectric films of P(VDF-TrFE) softened by a plasticizer are elaborated. Morphology, piezoelectric, mechanical, thermal, and crystalline properties of the films are studied. We show that the elastic constant is reduced up to 30% while increasing the remanent polarization and the piezoelectric coefficient thanks to the lubricant property of the plasticizer, helping the orientation of the crystallites. Plus, the decrease of the coercive field from 46 to 32 V/μm after an annealing at 138°C for a plasticizer content ranging between 20 and 50 wt% is observed and an explanation by based on a polymer/plasticizer demixing is provided. It leads to an easier polarization process with a significant saving in time and applied electric field reducing the breakdown voltage. Both effects could be interesting for an industrial production. Finally, a first sensor is elaborated and characterized electrically with homemade test bench. We show that the softening of the P(VDF-TrFE) offers to the device a larger amplitude range of deformations. The combination of the flexibility with high ferroelectric properties of the plasticized P(VDF-TrFE) make it a very promising material for biomedical sensor applications.  相似文献   
60.
Here we describe the effects of a controlled, 30 min, high-intensity cycling test on blood rheology and the metabolic profiles of red blood cells (RBCs) and plasma from well-trained males. RBCs demonstrated decreased deformability and trended toward increased generation of microparticles after the test. Meanwhile, metabolomics and lipidomics highlighted oxidative stress and activation of membrane lipid remodeling mechanisms in order to cope with altered properties of circulation resulting from physical exertion during the cycling test. Of note, intermediates from coenzyme A (CoA) synthesis for conjugation to fatty acyl chains, in parallel with reversible conversion of carnitine and acylcarnitines, emerged as metabolites that significantly correlate with RBC deformability and the generation of microparticles during exercise. Taken together, we propose that RBC membrane remodeling and repair plays an active role in the physiologic response to exercise by altering RBC properties.  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