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   469篇
  免费   27篇
电工技术   3篇
综合类   6篇
化学工业   124篇
金属工艺   4篇
机械仪表   3篇
建筑科学   38篇
矿业工程   1篇
能源动力   8篇
轻工业   80篇
水利工程   6篇
石油天然气   2篇
无线电   9篇
一般工业技术   80篇
冶金工业   58篇
原子能技术   1篇
自动化技术   73篇
  2024年   2篇
  2023年   3篇
  2022年   11篇
  2021年   20篇
  2020年   12篇
  2019年   12篇
  2018年   10篇
  2017年   20篇
  2016年   20篇
  2015年   22篇
  2014年   12篇
  2013年   29篇
  2012年   27篇
  2011年   33篇
  2010年   20篇
  2009年   40篇
  2008年   22篇
  2007年   18篇
  2006年   20篇
  2005年   16篇
  2004年   14篇
  2003年   9篇
  2002年   15篇
  2001年   4篇
  2000年   5篇
  1999年   4篇
  1998年   4篇
  1997年   7篇
  1996年   8篇
  1995年   7篇
  1994年   6篇
  1993年   5篇
  1992年   2篇
  1991年   4篇
  1990年   4篇
  1989年   2篇
  1988年   1篇
  1987年   3篇
  1985年   4篇
  1984年   3篇
  1983年   1篇
  1982年   4篇
  1981年   2篇
  1980年   1篇
  1979年   2篇
  1978年   1篇
  1977年   4篇
  1975年   1篇
排序方式: 共有496条查询结果,搜索用时 13 毫秒
51.
We propose a new semantic relation for gradable adjectives in WordNet, which enriches the present, vague, similar relation with information on the degree or intensity with which different adjectives express a shared attribute. Using lexical-semantic patterns, we mine the Web for evidence of the relative strength of adjectives like “large”, “huge” and “gigantic” with respect to their attribute (“size”). The pairwise orderings we derive allow us to construct scales on which the adjectives are located. To represent the intensity relation among gradable adjectives in WordNet, we combine ordered scales with the current WordNet dumbbells based on the relation between a pair of central adjectives and a group of undifferentiated semantically similar adjectives. A new intensity relation links the adjectives in the dumbbells and their concurrent representation on scales. Besides capturing the semantics of gradable adjectives in a way that is both intuitively clear as well as consistent with corpus data, the introduction of an intensity relation would potentially result in several specific benefits for NLP.  相似文献   
52.
We present a deterministic kinetic data structure for the facility location problem that maintains a subset of the moving points as facilities such that, at any point of time, the accumulated cost for the whole point set is at most a constant factor larger than the optimal cost. In our scenario, each point can change its status between client and facility and moves continuously along a known trajectory in a d-dimensional Euclidean space, where d is a constant.  相似文献   
53.
Conventional adaptive driving beam headlamps are limited in achieving still higher quantities of switchable pixels by the number of LEDs and movable elements needed. In this paper, it is shown that by integrating an active matrix liquid crystal display module, it is possible to realize fully adaptive high‐resolution headlights without mechanical elements and a finite number of LED with 30 k switchable pixels.  相似文献   
54.
Atom chips are a promising candidate for a scalable architecture for quantum information processing provided a universal set of gates can be implemented with high fidelity. The difficult part in achieving universality is the entangling two-qubit gate. We consider a Rydberg phase gate for two atoms trapped on a chip and employ optimal control theory to find the shortest gate that still yields a reasonable gate error. Our parameters correspond to a situation where the Rydberg blockade regime is not yet reached. We discuss the role of spontaneous emission and the effect of noise from the chip surface on the atoms in the Rydberg state.  相似文献   
55.
Within this paper the so-called artificial added mass effect is investigated which is responsible for devastating instabilities within sequentially staggered Fluid-structure Interaction (FSI) simulations where incompressible fluids are considered.A discrete representation of the added mass operator MA is given and ‘instability conditions’ are evaluated for different temporal discretisation schemes. It is proven that for every sequentially staggered scheme and given spatial discretisation of a problem, a mass ratio between fluid and structural mass density can be found at which the coupled system becomes unstable. The analysis is quite general and does not depend upon the particular spatial discretisation schemes used. However here special attention is given to stabilised finite elements employed on the fluid partition. Numerical investigations further highlight the results.  相似文献   
56.
Software measurement is considered important in improving the software process. However, teaching software measurement remains a challenging issue. Although, games and simulations are regarded powerful tools for learning, their learning effectiveness is not rigorously established. This paper describes the results of an explorative study to investigate the learning effectiveness of a game prototype on software measurement in order to make an initial judgment about its potential as an educational tool as well as to analyze its appropriateness, engagement and strengths & weaknesses as guidance for further evolution. Within the study, a series of experiments was conducted in parallel in three master courses in Brazil. Results of the study reveal that the participants consider the content and structure of the game appropriate, but no indication for a significant difference on learning effectiveness could be shown.
Djone KochanskiEmail:
  相似文献   
57.
A methodology, presented by Jaeckle and MacGregor [C.M. Jaeckle and J.F. MacGregor, Product Design Through Multivariate Statistical Analysis of Process Data, AIChE J. 44 (5) (1998) 1105–1118.], for finding a window of process operating conditions within which a product with specified quality characteristics can be produced is applied to two industrial polymerization processes. The approach uses historical data available on the process operating conditions and on the corresponding product quality for a range of existing product grades. Latent variable models — built using the existing data — are inverted to obtain a window of operating conditions, which are not only capable of yielding the desired product but are also consistent with past operating procedures and constraints. A semi-batch emulsion polymerization process for manufacturing various grades of a copolymer latex, and a batch solution polymerization process for manufacturing a range of polymer resins are considered.  相似文献   
58.
This study investigated the effects of organic and colloidal fouling on the removal of a representative micropollutant sulphamethoxazole by two commercially available NF membranes. Alginate, bovine serum albumin and colloidal silica were selected as model foulants to simulate hydrophilic and hydrophobic organic fractions, and colloidal matter that are often found in treated effluent and surface water. Membrane fouling was related to the membrane and foulant characteristics and subsequently the separation behaviour of the micropollutant sulphamethoxazole under different solution pH. On the basis of these results, it was confirmed that membrane fouling is strongly dependent on both the foulant and membrane characteristics. The complex relationship among retention mechanisms, fouling mechanisms and the effects of fouling on retention was systematically delineated. Of the three model foulants selected for this study, colloidal fouling resulted in the most significant reduction in retention of sulphamethoxazole as well as inorganic salts, while flux decline as a result of colloidal fouling was quite moderate. Reduction in retention caused by fouling was attributed to a phenomenon known as cake-enhance concentration polarisation, which was a predominant mechanism of colloidal fouling. In addition, the reported results suggested that the effect of fouling on retention is also membrane pore size dependent.  相似文献   
59.
Christiane Hipp 《AI & Society》1999,13(1-2):88-106
The new mode of knowledge production is seen as a distinct form of economic organisation used for exchanging and creating knowledge. The emphasis is laid on the role of business services in innovative networks as carriers of knowledge and intermediates between science (knowledge creator) and their customers (knowledge user). The empirical analysis shows that knowledge-intensive business services are able to make existing knowledge useful for, their customers, improving the customer's performance and productivity and contributing to technological and structural change.This paper is based on a presentation at the International Conference on Science, Technology and Society, 16–22 March 1998, Tokyo.  相似文献   
60.
 Two HPLC methods with diode array detection were used to separate Maillard products from milk components. The Maillard products 4-(β-d-galactopyranosyloxy)-2-hydroxy-2-methyl-2H-pyran-3(6H)-one (2), 1-[3-(β-d-galactopyranosyloxy)-2-furanyl]-1-ethanone (4), 4-(β-d-galactopyranosyloxy)-5-(hydroxymethyl)-2-methyl-3(2H)-furanone (5), isomaltol (7), maltol (9), 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one (6), and 5-hydroxymethyl-2-furfuraldehyde (8) were determined using a water-methanol gradient. Furthermore, 4,5-dihydroxy-2-(β-d-galactopyranosyloxy)-5-methyl-2-cyclopenten-1-one (3) was separated from the milk components by applying the interaction reagent octylamine. Several heated or processed milk samples were analyzed, and formation of the Maillard products was determined and quantified. Thus it was found that 2 and 3 are early products of the Maillard reaction in milk, whereas after prolonged heating 4, 5, and particularly 9 and 6 become more important. Compounds 7 and 8 were not detected, even if the samples were heated under stringent conditions.  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