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   6989篇
  免费   785篇
  国内免费   500篇
电工技术   528篇
技术理论   3篇
综合类   561篇
化学工业   623篇
金属工艺   292篇
机械仪表   281篇
建筑科学   454篇
矿业工程   86篇
能源动力   141篇
轻工业   180篇
水利工程   136篇
石油天然气   53篇
武器工业   17篇
无线电   998篇
一般工业技术   658篇
冶金工业   376篇
原子能技术   46篇
自动化技术   2841篇
  2024年   24篇
  2023年   110篇
  2022年   242篇
  2021年   263篇
  2020年   282篇
  2019年   196篇
  2018年   203篇
  2017年   209篇
  2016年   289篇
  2015年   296篇
  2014年   467篇
  2013年   526篇
  2012年   470篇
  2011年   656篇
  2010年   493篇
  2009年   447篇
  2008年   446篇
  2007年   490篇
  2006年   456篇
  2005年   294篇
  2004年   272篇
  2003年   198篇
  2002年   165篇
  2001年   133篇
  2000年   106篇
  1999年   82篇
  1998年   55篇
  1997年   53篇
  1996年   54篇
  1995年   25篇
  1994年   43篇
  1993年   29篇
  1992年   21篇
  1991年   20篇
  1990年   22篇
  1989年   14篇
  1988年   8篇
  1987年   13篇
  1986年   9篇
  1985年   10篇
  1984年   9篇
  1983年   6篇
  1982年   8篇
  1981年   8篇
  1978年   5篇
  1976年   8篇
  1974年   3篇
  1971年   5篇
  1965年   4篇
  1961年   4篇
排序方式: 共有8274条查询结果,搜索用时 0 毫秒
11.
The aim of our study was to further develop an understanding of social capital in organizational-knowledge-sharing. We first developed a measurement tool and then a theoretical framework in which three social capital factors (social network, social trust, and shared goals) were combined with the theory of reasoned action; their relationships were then examined using confirmatory factoring analysis. We then surveyed of 190 managers from Hong Kong firms, we confirm that a social network and shared goals significantly contributed to a person's volition to share knowledge, and directly contributed to the perceived social pressure of the organization. The social trust has however showed no direct effect on the attitude and subjective norm of sharing knowledge.  相似文献   
12.
The synthesis and properties of individual liquid crystal oligo(cyclosiloxanes),, wherex=4–8 andR is a 4-methoxyphenyl-4-alkyloxybenzoate type of mesogenic group, is described. Preliminary results concerning the effect of ring size on the mesophase formation are included. X-ray diffraction studies have shown that the cyclosiloxanes form a smectic A1 phase.  相似文献   
13.
Recent developments in the area of decentralized and infrastructureless systems opened avenues for novel applications. Along with these new technologies, new questions regarding their operational bounds in terms of e.g. scalability and security arose. Due to the sparse presence of real-world decentralized and infrastructureless systems, new protocols and applications have to be scrutinized by means of simulation, in (small-scale) testbeds, and by analytical models. In this paper, we discuss challenges of evaluating security mechanisms for mobile ad hoc networks and peer-to-peer systems. We focus on harmonizing predictions of analytical models and results obtained from simulation studies and testbed experiments.  相似文献   
14.
The problem of channel sharing by rate adaptive streams belonging to various classes is considered. Rate adaptation provides the opportunity for accepting more connections by adapting the bandwidth of connections that are already in the system. However, bandwidth adaptation must be employed in a careful manner in order to ensure that (a) bandwidth is allocated to various classes in a fair manner (system perspective) and (b) bandwidth adaptation does not affect adversely the perceived user quality of the connection (user quality). The system perspective aspect has been studied earlier. This paper focuses on the equally important user perspective. It is proposed to quantify user Quality of Service (QoS) through measures capturing short and long-term bandwidth fluctuations that can be implemented with the mechanisms of traffic regulators, widely used in networking for the purpose of controlling the traffic entering or exiting a network node. Furthermore, it is indicated how to integrate the user perspective metrics with the optimal algorithms for system performance metrics developed earlier by the authors. Simulation results illustrate the effectiveness of the proposed framework.
Leonidas GeorgiadisEmail:

Nikos G. Argiriou   received the Diploma degree in Electrical Engineering from the Department of Electrical Engineering, Telecommunication Division, Aristotle University of Thessaloniki, Greece, in 1996. He worked as a researcher, on secure medical image transmission over networks, at the Image Processing Lab at the same university during 1996–1997. During 1998–2000 he was a researcher for the European Project Esprit Catserver concerning the use of advanced Quality of Service techniques in CATV networks. He received his Ph.D. degree at Aristotle University of Thessaloniki in 2007. His current research interests are in the development and implementation of QoS techniques for wired and wireless networks. Leonidas Georgiadis   received the Diploma degree in Electrical Engineering from Aristotle University, Thessaloniki, Greece, in 1979, and his M.S. and Ph.D degrees both in Electrical Engineering from the University of Connecticut, in 1981 and 1986, respectively. From 1986 to 1987 he was Research Assistant Professor at the University of Virginia, Charlottesville. In 1987 he joined IBM T. J. Watson Research Center, Yorktown Heights as a Research Staff Member. Since October 1995, he has been with the Telecommunications Department of Aristotle University, Thessaloniki, Greece. His interests are in the area of wireless networks, high speed networks, routing, scheduling, congestion control, modeling and performance analysis.  相似文献   
15.
The backshapes of 114 seated persons were measured. The horizontal and vertical positions of various spinal landmarks are given for male and female subjects and for those with lordotic, straight and kyphotic backs.  相似文献   
16.
The parallelism attained by the use of Field Programmable Gate Arrays (FPGAs) has shown remarkable potential for accelerating control systems applications. This comes at a time when well established methods based on inherited serial Central Processor Units (CPUs) cannot guarantee solutions for the increasing execution speed demands. However, the transition from serial to parallel architectures represents a tremendous challenge due to overwhelming numbers of unexplored options and conflicting factors. The work presented achieves a parallelisation characterisation for generic MIMO systems using stand-alone FPGA implementations. The main contribution is that a very fine subset of possible serial/parallel implementations is obtained. This is used to achieve a flexible trade-off between cost and performance. Automatic optimisation of latency, occupied FPGA area and execution speed is attained and justified in respect to most of the feasible scenarios.  相似文献   
17.
23 highly hypnotizable undergraduates (Harvard Group Scale of Hypnotic Susceptibility) underwent 2 specially constructed 7-item hypnotic inductions. Over the 14 items, the main finding was of a relationship between E. R. Hilgard's (1973, 1977, 1979) "hidden observer" effect and 2 aspects of hypnotic age regression. Ss reporting a hidden observer experienced duality during regression to age 5, in which they were aware of being both adult and child. When asked to write a complex sentence, most did so, usually without spelling errors. The Ss not reporting this effect experienced quasi-lateral age regression in which they had the exclusive feeling of being 5 yrs old, with no sense of an adult identity. Most of these Ss were unable to write the same complex sentence when requested to during age regression. The study replicated Hilgard's finding of the hidden observer phenomenon in terms of its incidence and obtained similar verbal reports from Ss experiencing it. At the same time, the results suggest that a neodissociation account of hypnosis may need some modifications to accommodate these additional findings. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
18.
文章对电力系统稳定性研究内涵进行了评述,然后从认识论和方法论上加以分析,讨论了认识过程从功角稳定到电压稳定的转变、从线性向非线性的转变、从简单系统到复杂系统的转变、从重视解析方法到重视非解析方法的转变过程,为电力系统稳定性研究提供方法论指导。  相似文献   
19.
用于MIS的实时数据共享软件平台的设计与实现   总被引:1,自引:0,他引:1  
电网企业的各种信息,相互间具有相当紧密的关联关系,这些信息关联的核心就是电网实时数据。将电网实时数据引入到管理信息系统(MIS)中,使管理信息系统能够有效的分析利用实时数据对于促进电力系统的信息化发展具有重要意义。本文详细的阐述了用于管理信息系统(MIS)的电网实时数据共享软件平台的系统结构、工作原理以及设计与实现,提出了解决电网企业生产网和管理网信息共享以及MIS各个子系统同时共享调度实时数据的技术手段,并介绍了系统在电网信息管理系统中的具体应用。  相似文献   
20.
对工程项目管理系统的认识   总被引:1,自引:0,他引:1  
迟守学  王琦 《山东冶金》2004,26(4):30-31
工程项目管理系统是企业信息系统中关键的子系统。用于指导和协调其它子系统之间业务传递和数据共享。针对工程项目管理存在的信息沟通困难、数据易变化、书面文档多的难点,在建立工程项目管理系统时。可通过计算机网络系统、信息沟通系统、电子文档管理系统、项目数据管理系统等来实现对工程项目的管理。  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