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   152篇
  免费   4篇
电工技术   4篇
化学工业   15篇
金属工艺   2篇
机械仪表   1篇
建筑科学   10篇
能源动力   5篇
轻工业   20篇
水利工程   1篇
无线电   22篇
一般工业技术   27篇
冶金工业   10篇
自动化技术   39篇
  2024年   1篇
  2023年   1篇
  2021年   2篇
  2020年   1篇
  2019年   3篇
  2018年   5篇
  2017年   10篇
  2016年   5篇
  2015年   2篇
  2014年   7篇
  2013年   9篇
  2012年   9篇
  2011年   11篇
  2010年   13篇
  2009年   9篇
  2008年   6篇
  2007年   5篇
  2006年   9篇
  2005年   5篇
  2004年   2篇
  2003年   6篇
  2002年   5篇
  2001年   1篇
  2000年   1篇
  1999年   4篇
  1998年   5篇
  1997年   4篇
  1996年   3篇
  1995年   4篇
  1994年   3篇
  1993年   2篇
  1992年   1篇
  1985年   1篇
  1967年   1篇
排序方式: 共有156条查询结果,搜索用时 15 毫秒
101.
This study shows the sensitivity of the performance of a 30 nm Al2O3 barrier layer deposited by atomic layer deposition (ALD) on biaxially oriented polypropylene (BOPP) film to material processing. The most detrimental effects were caused by the contact between the rollers and the deposited layer during web handling and the surface contamination of the substrate prior to the deposition process. The shipment of the material as sheets and the atmospheric corona treatment of the coated surface had also a minor effect on the barrier performance. The results obtained show the importance of carrying out protective actions during both pre- and post-processing of the material in order to maintain the barrier performance of an ALD-Al2O3 layer.  相似文献   
102.
Carbonyl compounds formed in sea buckthorn berry (Hippophae rhamnoides) and oil samples as a result of lipid oxidation were determined by enzymatic hydrolysis followed by derivatisation with 2,4-dinitrophenylhydrazine and analysed by LC–UV and electrospray ionisation (ESI) tandem mass spectrometry (MS/MS). Several classes of carbonyl compounds such as saturated, unsaturated, linear and branched aldehydes and ketones, aromatic aldehyde, dicarbonyls and carboxy aldehydes were identified based on fragmentation pattern, molecular weight and retention time. The lower carbonyls such as formaldehyde, acetaldehyde and acetone were found to be predominant in the berry samples and acetaldehyde was found to be the most abundant carbonyl. In the sea buckthorn pulp oil sample, longer aldehydes and carboxy aldehydes dominated, thus clearly demonstrating the benefit of the enzymatic step when analysing oxidation products originating from triglycerides.  相似文献   
103.
Evolving video coding standards demand functional flexibility for implementations, not only at design time but also after fabrication. This paper presents a System-on-Chip design approach with a feasible combination of performance, scalability, programmability, area efficiency, and design time effort for a video encoder. The encoder is based on a homogeneous master-slave processor architecture. Each slave encodes a part of the frame in the Single Program Multiple Data (SPMD) data parallel model. Both shared and distributed memory architectures are presented. Design effort is reduced by identical program codes, automated assembly of software and hardware modules independent of the number and type of processors, as well as our flexible on-chip communication network called Heterogeneous IP Block Interconnection (HIBI). A case study implementation with two to ten simple ARM7 processors, 32-bit HIBI bus and non-optimized processor-independent software gives the performance from 6 to 53 fps for QCIF. The whole encoder area ranges from 173 to 770 kgates excluding the memories. The relation scales reasonably well to systems with more powerful processors and optimized code. The optimization of the communication network shows that with more than six slaves even a serial HIBI connection with 100 MHz speed is feasible. HIBI and the parallelization approach allow exploration and optimization of the communication both at the application and architecture layers. Tero Kangas, MSc ’01, Tampere University of Technology (TUT). Since 1999 he has been working as a research scientist in the Institute of Digital and Computer Systems (DCS) at TUT. Currently he is working towards his PhD degree and his main research topics are system architectures and SoC design methodologies in multimedia applications. Kimmo Kuusilinna, PhD ’01, TUT. His main research interests include system-level design and verification, interconnection networks, and parallel memories. Currently he is working as a senior research engineer at the Nokia Research Center. Timo D. H?m?l?inen, MSc ’93, PhD ’97, TUT. He acted as a senior research scientist and project manager at TUT in 1997-2001. He was nominated to full professor at TUT/Institute of Digital and Computer Systems in 2001. He heads the DACI research group that focuses on three main lines: wireless local area networking and wireless sensor networks, high-performance DSP/HW based video encoding, and interconnection networks with design flow tools for heterogeneous SoC platforms.  相似文献   
104.
Environmental tobacco smoke (ETS) is among the most common environmental health risks, with a striking and immediate biological response and increased disease risk. Exposure studies have looked mostly at worksite or home exposures, whereas total exposure levels at the population level are rarely reported. This study examined ETS exposure at work, at home, and during leisure time in a cross-sectional population sample of working-age adults. Our aim was to monitor changes in ETS exposure from 1992 to 2002. More detailed information on duration of exposure, distribution of exposure sites, and patterns of exposure was obtained in 2002. Data were based on Finland's national population chronic disease risk-factor surveys (conducted every 5 years). Total sample size varied from 8,000 to 13,500. The survey includes a self-administered questionnaire about ETS exposure at different sites. The proportion of nonsmoking persons exposed to ETS declined throughout the study period among both men and women. In 2002, 5.9% of male and 3.6% of female nonsmokers were exposed to ETS 1 hour or more per day, whereas 5.8% of men and 1.7% women were exposed less than 1 hour daily. Worksite exposure was more common among younger age groups of both sexes, but nonsmoking women in older age groups received more exposure at home than at worksites. Policy developments on ETS should aim to protect the whole population from ETS in all environments given that health risks from ETS often persist at home and in leisure environments. Total exposure levels should be studied to assess the health impacts of ETS.  相似文献   
105.
A published confirmatory method for the quantitative determination of four ionophoric coccidiostats (lasalocid, monensin, salinomycin and narasin) in eggs and broiler meat has been further developed. It is proposed for replacement of liquid chromatography methods previously used in analysis of ionophoric coccidiostats. The samples were extracted with acetonitrile and purified on a silica solid phase extraction column. Purified samples were analysed by liquid chromatography-mass spectrometry and the method, was validated according to the Commission Decision 2002/657/EC. The validation parameters selectivity, linearity, specificity, precision, recovery, decision limit (CCalpha) and detection capability (CCbeta) were determined. The recoveries of coccidiostats analysed ranged from 64-99% in eggs and 62-100% in broiler meat. CCalpha varied from 0.8-1.4 microg/kg in eggs and from 1.5-2.5 microg/kg in broiler meat. CCbeta varied from 0.9 microg/kg to 2.0 microg/kg in eggs and from 1.7-3.2 microg/kg in broiler meat.  相似文献   
106.
107.
This article focuses on typographical spellchecking. Typographical spellchecking verifies the use of characters such as ? ! - ; : \sp $ @ and other special purpose characters in respect to spaces or null elements. The author claims that this kind of spellchecking has not been developed to any substantial degree, although it could be of considerable practical use as writer's aid. The article discusses the basic challenges of typographical spellchecking and shows that some of the difficulties are greater than might be expected at first sight. Rules for describing the behavior of typographical characters are proposed.His research interests include computational linguistics and electronic publishing.  相似文献   
108.
109.
During the last 5 years, we have witnessed extraordinary development in the mobile market. Apple’s launch of the iOS platform and associated App Store marketplace turned the market around, and Apple became the leading company in the business. This development caused existing players, such as Nokia, to renew their business and attracted new players, such as Google and Microsoft, to enter the market and introduce their own mobile platforms. To understand this development, we suggest that a generic abstracted model of the ecosystem around mobile platforms should be developed describing how the actors, including users, individual app developers, companies, and digital services, are connected and interact. In this work, we propose that competition and collaboration in this kind of abstracted ecosystem can be modeled and analyzed using network analysis. In our research, we derived weighted competition and collaboration networks for each mobile platform from an expert survey, and by calculating companies’ degree centrality in their networks at different times we were able to illustrate how companies’ strategies to build and maintain an ecosystem differ and develop over time. We believe that this kind of analysis is useful both for companies that build ecosystems and also for companies that plan to do business in them. The former can use it to compare their strategy with existing competitors and also evaluate emerging new ecosystems and the latter to compare and choose between possible ecosystems with which to do business.  相似文献   
110.
The Finnish Wind Atlas was prepared applying the mesoscale model AROME with 2.5 km horizontal resolution and the diagnostic downscaling method Wind Atlas Analysis and Application Programme (WAsP) with 250 m resolution. The latter was applied for areas most favourable for wind power production: a 30 km wide coastal/offshore zone, highlands, large lakes and large fields. The methodology included several novel aspects: (i) a climatologically representative period of real 48 months during 1989–2007 was simulated with the mesoscale model; (ii) in addition, the windiest and calmest months were simulated; (iii) the results were calculated separately for each month and for sectors 30° wide; (iv) the WAsP calculations were based on the mesoscale model outputs; (v) in addition to point measurements, also radar wind data were applied for the validation of the mesoscale model results; (vi) the parameterization method for gust factor was extended to be applicable at higher altitudes; and (vii) the dissemination of the Wind Atlas was based on new technical solutions. The AROME results were calculated for the heights of 50, 75, 100, 125, 150, 200, 300 and 400 m, and the WAsP results for the heights of 50, 75, 100, 125 and 150 m. In addition to the wind speed, the results included the values of the Weibull distribution parameters, the gust factor, wind power content and the potential power production, which was calculated for three turbine sizes. The Wind Atlas data are available for each grid point and can be downloaded free of charge from dynamic maps at www.windatlas.fi . Copyright © 2011 John Wiley & Sons, Ltd.  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