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   325篇
  免费   19篇
  国内免费   1篇
电工技术   6篇
化学工业   83篇
金属工艺   4篇
机械仪表   12篇
建筑科学   3篇
能源动力   18篇
轻工业   30篇
水利工程   3篇
无线电   43篇
一般工业技术   62篇
冶金工业   11篇
原子能技术   9篇
自动化技术   61篇
  2023年   13篇
  2022年   21篇
  2021年   25篇
  2020年   31篇
  2019年   23篇
  2018年   36篇
  2017年   14篇
  2016年   20篇
  2015年   14篇
  2014年   22篇
  2013年   29篇
  2012年   16篇
  2011年   24篇
  2010年   10篇
  2009年   6篇
  2008年   3篇
  2007年   3篇
  2006年   1篇
  2005年   4篇
  2004年   1篇
  2003年   2篇
  2002年   2篇
  2001年   4篇
  2000年   1篇
  1999年   1篇
  1998年   3篇
  1993年   1篇
  1992年   1篇
  1988年   1篇
  1987年   1篇
  1986年   3篇
  1985年   3篇
  1984年   1篇
  1981年   2篇
  1980年   1篇
  1961年   1篇
  1954年   1篇
排序方式: 共有345条查询结果,搜索用时 93 毫秒
1.
Wireless Personal Communications - Routing is one of the most challenging task in mobile ad hoc networks. Several works have been proposed to address this challenge. Majority numbers of researchers...  相似文献   
2.
Iranian Polymer Journal - Numerous adverse effects are reported from excessive usage of synthetic polyolefins including major environmental concerns. Since then, the development of natural-based...  相似文献   
3.
4.
Due to high figure of merit, Ca3Co4 ? xO9 + δ (CCO) has potential as p-type material for high-temperature thermoelectrics. Here, the influence of processing including solid state sintering, spark plasma sintering and post-calcination on stability, microstructure and thermoelectric properties is reported. By a new post-calcination approach, single-phase materials were obtained from precursors to final dense ceramics in one step. The highest zT of 0.11 was recorded at 800 °C for CCO with 98 and 72% relative densities. In situ high-temperature X-ray diffraction in air and oxygen revealed a higher stability of CCO in oxygen (~970 °C) than in air (~930 °C), with formation of Ca3Co2O6 which also showed high stability in oxygen, even at 1125 °C. Since achievement of phase pure high density CCO by post-calcination method in air is challenging, the phase stability of CCO in oxygen is important for understanding and further improvement of the method.  相似文献   
5.
Theoretical Foundations of Chemical Engineering - In this study, the simulations for first-order chemical reactions (constructive and destructive) in the flow of the Casson fluid with...  相似文献   
6.
Abstract

Industry 4.0 aims at providing a digital representation of a production landscape, but the challenges in building, maintaining, optimizing, and evolving digital models in inter-organizational production chains have not been identified yet in a systematic manner. In this paper, various Industry 4.0 research and technical challenges are addressed, and their present scenario is discussed. Moreover, in this article, the novel concept of developing experience-based virtual models of engineering entities, process, and the factory is presented. These models of production units, processes, and procedures are accomplished by virtual engineering object (VEO), virtual engineering process (VEP), and virtual engineering factory (VEF), using the knowledge representation technique of Decisional DNA. This blend of the virtual and physical domains permits monitoring of systems and analysis of data to foresee problems before they occur, develop new opportunities, prevent downtime, and even plan for the future by using simulations. Furthermore, the proposed virtual model concept not only has the capability of Query Processing and Data Integration for Industrial Data but also real-time visualization of data stream processing.  相似文献   
7.
Prion‐reduction in standard biodiesel processes is caused by acidic and alkaline conditions. In the alternative RepCat biodiesel process, efficient prion‐reduction can be achieved by high‐temperature/pressure. However, a possible increase in thermostability of prions in the presence of methanol during these conditions has not previously been investigated, and is verified in this work. Samples are spiked with prions, treated with methanol, and incubated at 220 °C at 80 bar for 30 min. No traces of protease‐resistant prion protein (as proxy for prions) are detected in tallow or glycerine (as the final by‐product) after treatment. Serial dilutions of spiked prions show at least 6 log10 prion reduction. More importantly, similar effects are detected using milder conditions of 200 °C at 70 bar for 15 min, representing the worst‐case conditions of the process. In conclusion, this study shows that methanol does not increase the thermostability of prions and the RepCat process can efficiently eliminate prions and is therefore safe for the usage of category 1 tallow. Practical Applications: The study further supports the applicability of RepCat process in reducing prion‐contamination in the presence of methanol. Furthermore, the conditions leads to a considerable reduction of prions in glycerine obtained as by‐product.  相似文献   
8.
9.
Surface treatment of cellulose fibers was performed with maleated high oleic sunflower oil (MSOHO). The MSOHO‐treated cellulose fibers and unmodified cellulose fibers were dispersed in styrene butadiene rubber (SBR) using a two roll mill. Vapor grown carbon nanofibers (VGCNF) were also incorporated at only one parts per hundred rubber (phr) in unmodified cellulose fibers/SBR composites. The curing characteristics, mechanical properties, and water absorption of the resulting composites were determined. MSOHO‐treated fibers completed curing at much slower rate and also decreased the cure density of composites, compared to unmodified fibers. In contrast, the combination of VGCNF and unmodified cellulose fibers accelerated the SBR curing process, but reduced the cure density. MSOHO treatment improved the dispersion of the fibers in the SBR, which resulted in improved mechanical properties of composites. The composite incorporating 1 phr VGCNF and 15 phr unmodified cellulose fibers showed the greatest increase in tensile strength as compared with neat SBR. POLYM. COMPOS. 37:1113–1121, 2016. © 2014 Society of Plastics Engineers  相似文献   
10.
In order to analyze potential social risks, and achieve smooth implementation of investment activities in the China–Pakistan economic corridor (CPEC), we attempt to establish social impact and risk indicators. Both the impacts on the projects and the impacts of the projects are used to develop risk indicators in accordance with the literature review, reality and international standard principles. Using an analytic hierarchy process (AHP) and average value to analyze questionnaires of both Chinese and Pakistani respondents, we identify the importance of various risk indicators. The primary social risks of the western high mountain region include tribal obstacles and religious extremism. The social risks to the southeast coastal plains include preserving the historical and cultural heritage of the area and international protection of national parks. The social risks in north Kashmir include disputes, extremist threats, religious and cultural differences, and the protection of natural reserves. The social risks of the Xinjiang region primarily involve social issues faced by ethnic minorities and environmental pressures.  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