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   86951篇
  免费   18485篇
  国内免费   3160篇
电工技术   3856篇
技术理论   1篇
综合类   3931篇
化学工业   24539篇
金属工艺   3182篇
机械仪表   3955篇
建筑科学   5137篇
矿业工程   1312篇
能源动力   2019篇
轻工业   12314篇
水利工程   1406篇
石油天然气   2062篇
武器工业   464篇
无线电   12368篇
一般工业技术   16615篇
冶金工业   2502篇
原子能技术   612篇
自动化技术   12321篇
  2024年   278篇
  2023年   823篇
  2022年   1603篇
  2021年   2264篇
  2020年   2931篇
  2019年   4372篇
  2018年   4510篇
  2017年   4951篇
  2016年   5314篇
  2015年   5981篇
  2014年   6442篇
  2013年   8165篇
  2012年   6408篇
  2011年   6521篇
  2010年   6379篇
  2009年   6166篇
  2008年   5611篇
  2007年   5211篇
  2006年   4708篇
  2005年   3888篇
  2004年   3174篇
  2003年   2711篇
  2002年   2591篇
  2001年   2207篇
  2000年   1914篇
  1999年   1097篇
  1998年   444篇
  1997年   375篇
  1996年   302篇
  1995年   225篇
  1994年   206篇
  1993年   173篇
  1992年   131篇
  1991年   113篇
  1990年   76篇
  1989年   61篇
  1988年   42篇
  1987年   44篇
  1986年   38篇
  1985年   16篇
  1984年   13篇
  1983年   16篇
  1982年   17篇
  1980年   8篇
  1979年   11篇
  1978年   11篇
  1977年   11篇
  1976年   13篇
  1975年   9篇
  1970年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
He and Grigoryan (Quality and Reliability Engineering International 2002; 18 :343–355) formulated the design of a double‐sampling (DS) s control chart as an optimization problem and solved it with a genetic algorithm. They concluded that the DS s control charts can be a more economically preferable alternative in detecting small shifts than traditional s control charts. We explain that, since they only considered the average sample size when the process is in control, their conclusion is questionable. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
102.
103.
Discovering unknown adverse drug reactions (ADRs) in postmarketing surveillance as early as possible is highly desirable. Nevertheless, current postmarketing surveillance methods largely rely on spontaneous reports that suffer from serious underreporting, latency, and inconsistent reporting. Thus these methods are not ideal for rapidly identifying rare ADRs. The multiagent systems paradigm is an emerging and effective approach to tackling distributed problems, especially when data sources and knowledge are geographically located in different places and coordination and collaboration are necessary for decision making. In this article, we propose an active, multiagent framework for early detection of ADRs by utilizing electronic patient data distributed across many different sources and locations. In this framework, intelligent agents assist a team of experts based on the well‐known human decision‐making model called Recognition‐Primed Decision (RPD). We generalize the RPD model to a fuzzy RPD model and utilize fuzzy logic technology to not only represent, interpret, and compute imprecise and subjective cues that are commonly encountered in the ADR problem but also to retrieve prior experiences by evaluating the extent of matching between the current situation and a past experience. We describe our preliminary multiagent system design and illustrate its potential benefits for assisting expert teams in early detection of previously unknown ADRs. © 2007 Wiley Periodicals, Inc. Int J Int Syst 22: 827–845, 2007.  相似文献   
104.
赵婧华  卢敏 《电子工程师》2004,30(11):37-39
空时分集技术的最大优点在于在不增加带宽的情况下可以提高系统的可靠性,是目前移动通信的研究热点.常模算法是一种性能优良的码分多址(CDMA)盲多用户检测技术,能确保判决信号与实际传送信号之间的差错较小,误码率性能良好.文中提出将标准线性受限常模算法(LCCMA)与空时分组码(STBC)相结合,设计出一种收敛快、能够改善系统性能的基于2-空时分组码的多用户接收机.  相似文献   
105.
A novel strategy of sweep coagulation to treat low turbidity water is presented herein. Study findings demonstrated that an Na+‐saturated bentonite with medium cation exchange capacity (CEC) resulted in significant turbidity removal at a bentonite dosage of 30 mg dm?3. Bentonite dispersion with fully delaminated platelets tended to undergo a more porous type of coagulation with intense face‐to‐face interactions of platelets and effectively entrapped TiO2 particles in band‐type structures. This type of coagulation usually results in a large volume of settled flocs with a fluffy structure and excellent turbidity removal efficiency for sweep coagulation. The sign and magnitude of electrical charge on TiO2 particles has a minor effect on the efficiency of sweep coagulation. Copyright © 2005 Society of Chemical Industry  相似文献   
106.
Liquid–liquid two‐phase epoxidation from cyclohexene and cyclooctene in aqueous potassium peroxymonosulfate (commercially available as Oxone®) solution was studied as an application in pollution prevention. To avoid potential emissions of volatile organic compounds an aqueous solution was employed to replace the usual chlorinated solvents used in epoxide production. A droplet column reactor and stirred tank reactor were used to investigate two‐phase synthesis of epoxide. An aqueous Oxone® solution was used to oxidize a dispersion of alkene droplets and form epoxide. The study of aqueous epoxidation in both reactors showed that the epoxidation of alkenes can be represented as a first order reaction with respect to alkene. The salting out effect of Oxone® concentration was studied in both reactors and found to be very similar at optimal conditions. In comparing the two reactors, it was found that the droplet column reactor produces larger quantities of product per unit reactor volume for the same reaction time. The objective of this study is to provide an alternative reactor design and synthesis route that can meet pollution prevention goals. Copyright © 2004 Society of Chemical Industry  相似文献   
107.
108.
Jiyoung Hwang  Bumsuk Jung  Min Park 《Polymer》2005,46(21):9133-9143
Microstructures of hundreds of micron thick poly(styrene-block-isoprene) copolymer films solution-cast in a cylindrical tube with the solvent evaporation controlled were investigated by transmission electron microscope (TEM), small angle X-ray scattering (SAXS) and optical microscope (OM). In a block copolymer with cylindrical polyisoprene microdomains, the orientation of the cylinders was varied along radial direction of the cylindrical tube. Highly aligned hexagonal arrays of in-plane polyisoprene cylinders were formed with their cylindrical axis parallel to the circumference of the tube in the regimes close to the wall edge. In contrast randomly ordered microdomains were observed at the center of the tube. We have also found that the orientation depends on the solvent evaporation rate and an intermediate rate (∼2.3 nL/s) provides the best orientation. In the case of a block copolymer with a bicontinuous double gyroid structure, we obtained a globally ordered microstructure where [111] crystallographic direction was parallel to the circumference of the tube. For both block copolymers, the area of highly ordered arrays of nanoscopic domains is over 1 mm2. Development of the orientation was explained by coupling two orthogonal fields: (1) The flow of a solution induced by strong capillary force at a meniscus between the cylindrical tube wall and the block copolymer solution and (2) the solvent evaporation.  相似文献   
109.
110.
谢敏 《电子工程师》2005,31(6):43-45
双口RAM与常规RAM的最大区别是双口RAM具有两套独立的地址、数据和控制线,允许两个独立的CPU或控制器同时异步地访问存储单元,双口RAM由片内的仲裁逻辑来确定哪一侧的CPU可以访问内部RAM单元.IDT7132是2kB的标准双口RAM.文中重点介绍采用以自顶向下方法设计的基于CLD(复杂可编程逻辑器件)的大屏幕LED(发光二极管)显示系统中双口RAM的应用,并给出了系统设计方法及相关硬件电路.本设计中IDT7132双口RAM用来连接单片机信号处理模块和CPLD扫描模块.  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