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   5053篇
  免费   354篇
  国内免费   172篇
电工技术   200篇
综合类   254篇
化学工业   826篇
金属工艺   223篇
机械仪表   210篇
建筑科学   344篇
矿业工程   142篇
能源动力   114篇
轻工业   298篇
水利工程   91篇
石油天然气   152篇
武器工业   46篇
无线电   690篇
一般工业技术   723篇
冶金工业   629篇
原子能技术   53篇
自动化技术   584篇
  2024年   23篇
  2023年   86篇
  2022年   159篇
  2021年   217篇
  2020年   120篇
  2019年   132篇
  2018年   149篇
  2017年   160篇
  2016年   127篇
  2015年   190篇
  2014年   188篇
  2013年   248篇
  2012年   260篇
  2011年   305篇
  2010年   259篇
  2009年   251篇
  2008年   290篇
  2007年   228篇
  2006年   206篇
  2005年   163篇
  2004年   110篇
  2003年   103篇
  2002年   102篇
  2001年   106篇
  2000年   120篇
  1999年   137篇
  1998年   233篇
  1997年   157篇
  1996年   112篇
  1995年   71篇
  1994年   70篇
  1993年   63篇
  1992年   33篇
  1991年   29篇
  1990年   23篇
  1989年   28篇
  1988年   27篇
  1987年   22篇
  1986年   28篇
  1985年   14篇
  1984年   27篇
  1983年   17篇
  1982年   17篇
  1980年   8篇
  1979年   9篇
  1978年   13篇
  1977年   8篇
  1976年   34篇
  1975年   8篇
  1956年   8篇
排序方式: 共有5579条查询结果,搜索用时 15 毫秒
1.
Global competition is driving manufacturing companies to change the way they do business. New kinds of shop floor control systems need to be implemented for these companies to respond quickly to changing shop floor environments and customer demands. This paper presents a new concept called iShopFloor-an intelligent shop floor based on the Internet, web, and agent technologies. It focuses on the implementation of distributed intelligence in the manufacturing shop floor. The proposed approach provides the framework for components of a complex control system to work together as a whole rather than as a disjoint set. It encompasses both information architecture and integration methodologies. The paper introduces the basic concept of iShopFloor, a generic system architecture, and system components. It also describes the implementation of eXtensible Markup Language message services in iShopFloor and the application of intelligent agents to distributed manufacturing scheduling. A prototype environment is presented, and some implementation issues are discussed.  相似文献   
2.
H.H Qi  P.L Lang  T.S Wang  Y.J Tian 《低温学》2004,44(10):695-699
We have fabricated and tested a high-Tc dc-SQUID magnetometer patterned on a YBCO thin film deposited on a SrTiO3 bicrystal substrate. The measurement of noise spectrum at 77 K showed that the magnetometer has a white noise of 333 fT/Hz1/2 without superconducting shield, corresponding to a flux sensitivity of 14.5 μΦ0/Hz1/2. We constructed a test system for eddy current non-destructive evaluation of conducting aluminum plates by using the magnetometer. Flaws over 10 mm below the surface can be clearly identified. By mapping the magnetic field distribution, we can locate the flaw position. The signals caused by flaw were expanded due to the use of double-D type driving coil with a wider central slit. The experimental results confirmed that this test system could operate in a magnetic unshielded environment.  相似文献   
3.
The preoxidation of a highly polluted waste pharmaceutical fermentation broth using wet air oxidation (WAO) has been studied as a possible method for the effective removal of organics. The applied (pre)treatment method should enhance the biotreatability of the pharmaceutical fermentation broth in terms of reduced initial toxicity and higher biodegradability. Preliminary experiments in the pilot biological treatment plant were successful only at low organic loads, whereas the system collapses at higher ones. The characterization of the fermentation broth was started by common physicochemical analysis, whereas several bioassays were used to determine its impact on biological treatment plants and the environment. Toxicity prior to and after WAO was determined using the acute Vibrio fischeri test, measurement of inhibition of O2 consumption, and the Daphnia magna acute test. Ready biodegradability of the treated and untreated broth has also been assessed. WAO experiments were accomplished in the 2?L batch reactor at different temperatures (240/280°C) and operating pressures. WAO experiments confirmed reduction of the toxicity toward microorganisms, whereas oxidized wastewater was more toxic to daphnids. Biodegradability of the oxidized broth has also been enhanced. Further work has been focused on designing appropriate combination of WAO and biological processes.  相似文献   
4.
5.
6.
7.
Mesh network resiliency using GMPLS   总被引:4,自引:0,他引:4  
The generalized multiprotocol label switching (GMPLS) is being developed as the control plane for the evolving photonic network. We describe how GMPLS can be used with mesh networks to provide efficient network resiliency. In particular we examine the key aspects of GMPLS that are used to support protection and restoration. We also study the various protection and restoration techniques, and we highlight the tradeoffs between recovery time and resource redundancy  相似文献   
8.
Magnetic induction micromachine-part I: Design and analysis   总被引:1,自引:0,他引:1  
Most microscale electric and magnetic machines studied in the last decade lack the power density to support many practical applications. This paper introduces a design for a magnetic induction machine that offers power densities in excess of 200 MW/m/sup 3/ and efficiencies of up to 50%, while providing more than 10 W of mechanical power. This is a substantial performance increase in MEMS electromagnetic machines studied to date.  相似文献   
9.
The authors describe a 9.02×9.02-mm chip built in 1-μm CMOS with two levels of metal and an additional mask level for fabricating capacitors. It contains both analog and digital circuits and has provisions for self-test. The function includes the transmitter, receiver, protocol handler, an microprocessor, as well as interfaces for RAM/ROM storage, IBM PC bus, IBM PS/2 bus, IBM 3174 bus, and Motorola 68000 bus. The physical design terrains are formed by 24K circuits of standard cell gates, a 10K-circuit equivalent hand-honed custom microprocessor, and an analog macro. The chip operates from a single 5-V supply, and the power consumption is 0.8 W nominal at 16 Mb/s. The chip can also be operated at 4 Mb/s  相似文献   
10.
This paper reports the findings of a detailed study of Web-based systems design (WBSD) practices in Ireland based on data collected over a 3-year period (2002–2005), the objectives of which were to (1) contribute towards a richer understanding of the current “real-world” context of WBSD by characterising the profile of a typical project (team size, timeframe, nature of requirements, etc.) and identifying the key challenges, constraints, and imperatives (i.e. “mediating factors”) faced by Web-based system designers, and (2) understand how those contextual parameters and mediating factors influence the activity of WBSD as regards the selection and enactment of whatever design practices are therefore engaged (i.e. the use of methods, procedures, etc.). Data was gathered through a survey which yielded 165 usable responses, and later through a series of semi-structured qualitative interviews. Using grounded theory, an explanatory conceptual framework is derived, based on an extension of the “method-in-action” model, the application of which to WBSD has not been previously investigated in depth. It is proposed that this framework of WBSD issues is valuable in a number of ways to educators, researchers, practitioners, and method engineers.  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