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   2270篇
  免费   121篇
  国内免费   2篇
电工技术   28篇
综合类   1篇
化学工业   565篇
金属工艺   53篇
机械仪表   67篇
建筑科学   70篇
矿业工程   2篇
能源动力   46篇
轻工业   210篇
水利工程   4篇
石油天然气   18篇
无线电   170篇
一般工业技术   431篇
冶金工业   281篇
原子能技术   20篇
自动化技术   427篇
  2024年   4篇
  2023年   20篇
  2022年   48篇
  2021年   91篇
  2020年   37篇
  2019年   46篇
  2018年   76篇
  2017年   69篇
  2016年   107篇
  2015年   59篇
  2014年   85篇
  2013年   163篇
  2012年   138篇
  2011年   170篇
  2010年   91篇
  2009年   119篇
  2008年   115篇
  2007年   116篇
  2006年   85篇
  2005年   54篇
  2004年   64篇
  2003年   62篇
  2002年   47篇
  2001年   36篇
  2000年   37篇
  1999年   31篇
  1998年   58篇
  1997年   38篇
  1996年   44篇
  1995年   31篇
  1994年   26篇
  1993年   13篇
  1992年   15篇
  1991年   10篇
  1990年   17篇
  1989年   15篇
  1988年   10篇
  1987年   16篇
  1986年   10篇
  1985年   18篇
  1984年   10篇
  1983年   17篇
  1982年   9篇
  1981年   8篇
  1979年   10篇
  1978年   5篇
  1977年   11篇
  1976年   12篇
  1975年   4篇
  1973年   5篇
排序方式: 共有2393条查询结果,搜索用时 15 毫秒
991.
G. Lukatela and M. T. Turvey (1994x) showed that at a 57-ms prime-presentation duration, the naming of a visually presented target word (frog) is primed not only by an associate word (toad) but also by a homophone (towed) and a pseudohomophone (tode) of the associate. At a 250-ms prime presentation, priming with the homophone was no longer observed. In Experiment 1, the authors replicated these priming effects in the Dutch language. Next, the authors extended the priming paradigm to a word/legalnon-word lexical decision task (Experiments 2 and 3) and a word/pseudohomophone decision task (Experiment 4). Phonologically mediated associative priming was observed in all conditions with pseudohomophonic primes but not with homophonic primes. The latter did not prime at a 250-ms prime-presentation time and at 57 ms in the word/pseudohomophone task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
992.
993.
The gasification of a metallurgical coke with CO2/N2 mixtures in a 0.1 m diameter fluidised bed has been studied over the temperature range 810–1050°C. The rate of gasification was found to be essentially kinetically controlled, with negligible influence of fluidisation parameters below 1000°C. A number of flow models were assessed. The plug flow model was found to be the simplest model which could predict the experimental results, giving similar results to the more complex two-phase flow model of Davidson and Harrison (1963). For the range of conditions studied, the simple nth order reaction model was used to determine a best value of the reaction order of 0.8. For this combination of flow and reaction models, an activation energy of 197 kJ/mol was deduced from the experiments, in agreement with packed bed results and literature data. Very simple models can be used to predict the experimental results within the range studied.  相似文献   
994.
995.
Seeds of Brassica napus L cv Mikado contain about 25% w/w protein in addition to 40–50% w/w storage oil. About 50% of the seed protein is the legumin-like neutral protein, cruciferin, and a further 20% is the small basic protein, napin. The only other major seed protein (20% of total) is a polypeptide of apparent molecular mass (Mr) 19 000±200, which is associated with the membranes of the storage oil-bodies. The purification of this protein and preparation of monospecific antibodies have recently been reported. The kinetics of protein and oil mobilisation and the subcellular distribution of the Mr 19 000 oil-body protein have been studied by techniques including sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), gas-liquid chromatography (GLC), sucrose density gradient fractionation, and electron microscop-immunocytochemistry. The results show that the mobilisation of the storage products of rapeseed occurs in at least three distinct phases: (1) a lag phase of 10–15 h, (2) breakdown of cruciferin and napin from 12 h until day 3, (3) breakdown of storage oil and oil-body membranes from day 2 until day 7. The Mr 19000 protein was localised on oil-body membranes in early stages of germination but was later associated with a light membrane fraction, which probably contained oil-body ghosts. Relatively little difference in the kinetics of the mobilisation of storage oils and proteins was found whether seedlings were grown in the light or in the dark. The implications of these results for the mechanism of storage oil mobilisation in oilseeds are discussed.  相似文献   
996.
Causal explanation takes place in and takes the form of conversation. Explanations are selected by questions and are thus governed by general rules of discourse. A conversational model of causal explanation is introduced that explicates social aspects of the explanation process by postulating that good explanations must be relevant to the focus of a why question, as well as being true. The notion of explanatory relevance enables an integration of the major models of the attribution process by showing that they use the same counterfactual logic but address different causal questions. The conversational perspective suggests a reinterpretation of many attributional biases, and also highlights the role of interpersonal goals in generating implicit questions, which in turn constrain explanations. Finally, the relevance of the conversational perspective for research on causal networks, the social context of explanation, and intrapsychic explanation is noted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
997.
Botrytized wines (BW) are famous for their distinctive, complex aromas. To date, only a few studies have analysed the volatile compounds involved in their typical flavours. In this paper, GC–O was applied to BW and dry white wines (DW) made from the same grape varieties to characterize the main odorants responsible for their sensory differences. Surprisingly, only two odorous zones, with grapefruit or curry nuances, were apparently specific to BW. However, GC–AEDA revealed important differences in the FD values between BW and DW, making it possible to screen potent odorants of BW, such as 3-mercaptohexan-1-ol, homofuraneol®, furaneol®, sotolon, methional, and phenylacetaldehyde. GC–MS quantification of homofuraneol®, furaneol®, norfuraneol®, phenylacetaldehyde, and methional in 14 BW, mostly at levels above their perception thresholds, confirmed their contribution to the aroma of BW. Increased concentrations of some of these odorants in BW were shown to be associated with grape botrytization, partially through the desiccation process.  相似文献   
998.
Although computerization is increasingly advocated as a means for hospitals to enhance quality of care and control costs, few studies have evaluated its impact on the day-to-day organization of medical work. This study investigated a large Computerized Patient Record (CPR) project ($50 million U.S.) aimed at allowing physicians to work in a completely electronic record environment. The present multiple-case study analyzed the implementation of this project conducted in four hospitals. Our results show the intricate complexity of introducing the CPR in medical work. Profound obstructions to the achievement of a tighter synchronization between the care and information processes were the main problems. The presence of multiple information systems in one (Communication, Decision Support, and Archival record keeping) was overlooked. It introduced several misconceptions in the meaning and codification of clinical information that were then torn apart between information richness to sustain clinical decisions and concision to sustain care coordination.  相似文献   
999.
1000.
We address the problem of maintaining logical time in a distributed system operating over a wireless data network. In such a network a group of mobile nodes currently located in a specific area use services of a mobility service agent to communicate with each other and with the rest of the world. The graph model of the network is represented by fully-connected mesh of star-topology subgraphs. We discuss the complementary logical clocks for the wireline and wireless segment of the network and their integration into an isomorphic logical time system.  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