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   2156篇
  免费   82篇
  国内免费   97篇
电工技术   14篇
综合类   29篇
化学工业   670篇
金属工艺   46篇
机械仪表   44篇
建筑科学   53篇
矿业工程   12篇
能源动力   165篇
轻工业   36篇
水利工程   4篇
石油天然气   48篇
武器工业   3篇
无线电   214篇
一般工业技术   130篇
冶金工业   11篇
原子能技术   14篇
自动化技术   842篇
  2024年   11篇
  2023年   38篇
  2022年   74篇
  2021年   76篇
  2020年   69篇
  2019年   70篇
  2018年   57篇
  2017年   95篇
  2016年   96篇
  2015年   65篇
  2014年   122篇
  2013年   126篇
  2012年   91篇
  2011年   187篇
  2010年   106篇
  2009年   131篇
  2008年   156篇
  2007年   126篇
  2006年   105篇
  2005年   107篇
  2004年   81篇
  2003年   63篇
  2002年   45篇
  2001年   30篇
  2000年   33篇
  1999年   41篇
  1998年   19篇
  1997年   15篇
  1996年   17篇
  1995年   17篇
  1994年   10篇
  1993年   13篇
  1992年   8篇
  1991年   11篇
  1990年   4篇
  1989年   4篇
  1988年   5篇
  1987年   5篇
  1986年   1篇
  1985年   3篇
  1983年   1篇
  1980年   1篇
排序方式: 共有2335条查询结果,搜索用时 15 毫秒
81.
网络与终端协同选择及切换机制的研究   总被引:1,自引:1,他引:0  
提出了一种智能切换机制,用于实现在异构网络中网络与终端的协同选择及切换功能。随着各种业务和应用的发展,异构网络融合是信息和通信技术的必然趋势。根据多接入、多终端等应用环境的要求,采用AHP与URA等多属性决策理论,为用户选择最佳的目标网络和目标终端,并提出相应的智能切换信令流程,包括网络切换、终端切换、网络与终端联合切换方式,最终构建以用户为中心的多终端智能空间,实现个人移动性管理。仿真表明,该智能切换机制可以有效地实现网络和终端的协同选择,并可以保证在异构网络切换QoS性能,为现代服务业的业务及应用的发展提供可靠的理论依据。  相似文献   
82.
应用系统信息集成是管控一体化的研究热点。本文分析了跨级别应用系统信息集成的目标和面临的问题,结合Web服务的技术特性,提出一种基于Web服务进行异构系统信息集成的方法,最后给出了一个实际应用案例来验证该方法。  相似文献   
83.
A new approach, called the “variational theory of complex rays” has been developed in order to calculate the vibrations of slightly damped elastic plates in the medium-frequency range. The resolution of a small system of equations which does not result from a fine spatial discretization of the structure leads to the evaluation of effective quantities (deformation energy, vibration amplitude,…). Here, we extend this approach, which was already validated for assemblies of homogeneous substructures, to the case of heterogeneous substructures.  相似文献   
84.
使用XML进行异构数据库间数据传送   总被引:4,自引:0,他引:4  
本文提出利用中间数据源XML进行异构数据库间数据传送的方案,对如何实现在数据库数据类型与XML数据类型之间进行转换,如何生成XML文件,如何向XML文件写入被传输数据的实现策略进行了探讨。  相似文献   
85.
智能楼宇综合管理系统的设计   总被引:7,自引:0,他引:7  
首先介绍了智能楼宇系统集成的问题,然后对智能楼宇综合管理系统的体系结构进行了设计分析了其特点,最后对其关键技术进行了研究。  相似文献   
86.
This paper explores the suitability of the emerging passive star-coupled optical interconnection using wavelength division multiplexing as the system interconnect to provide high bandwidth (Gbits/sec) communication demanded by heterogeneous systems. Several different communication strategies (combinations of communication topologies and protocols) are investigated under a representative master-slave computational model. The interplay between system speed, network speed, task granularity, and degree of parallelism is studied using both analytical modeling and simulations. It is shown that a hierarchical ALOHA-based communication strategy between the master and the slaves, implemented on top of the passive star-coupled network, leads to a considerable reduction in channel contention and provides 50–80% reduction in task completion time for applications with medium to high degrees of coarse grain parallelism. Comparable reduction in channel contention is also shown to be achieved by using tunable acoustooptic filters at master nodes.  相似文献   
87.
We outline an extendible approach for combining formal methods – such as Z, Morgan's refinement calculus, and predicative programming – based on composing specifications written in similar formal languages. We discuss how algorithm refinement can be extended to such a setting, and outline some examples of using integrated formal methods. We also provide justifications for why using combinations of similar methods might be helpful. Received November 1996 / Accepted in revised form August 1998  相似文献   
88.
A technique for scheduling and processor allocation leading to the synthesis of integrated heterogeneous pipelined processing elements, implementing digital signal processing applications, is proposed. The proposed technique achieves efficient hardware implementations at the logic-level by minimizing the number of processing units used, without compromising the rate and delay optimality criteria.

The proposed algorithm is found to outperform algorithms resulting in homogeneous implementations, as it gives schedules with lower iteration periods, requires less hardware resources, and has lower time complexity at design time. In comparison with the already existing heterogeneous algorithms, the proposed algorithm produces schedules of lower time complexity and lower iteration period for some applications. The optimal performance of the proposed algorithm has been verified on several benchmarks.  相似文献   

89.
The advanced plasma electrochemical process of anodic spark deposition (ASD) was used to generate photoactive titanium dioxide films on titanium metal substrates. A shift to easier-to-machine substrates was demonstrated by the deposition of a titanium film with physical vapour deposition onto different materials such as glass, silicon, and stainless steel prior to ASD. Obtained films were characterised by scanning electron microscopy, surface area measurement (Brunnauer-Emmett-Teller method, BET), X-ray diffraction, electron-probe microanalysis, and glow discharge spectroscopy. Additionally, film thickness was determined by eddy current measurements. Standard ASD conditions were defined as 180 V applied voltage over a 180 s hold time, a voltage ramp of 20 V/s, a duty cycle of 0.5 and a frequency of 1500 Hz. Most prominent characteristics of the titanium films produced under these standard conditions are a film thickness of ≤80 μm, a surface area of approximately 51 m2/g (BET) and an anatase content of approximately 30% and rutile content of approximately 70%. Furthermore, the film formation process is elucidated and the dependence of film thickness on deposition time and the dependence of the anatase and rutile content on the deposited mass are shown for varying ASD conditions.  相似文献   
90.
There appear more critical requirements for special functions of components/products in various areas, which can be satisfied only by using heterogeneous materials and/or smart materials. The heterogeneous materials include composite materials, functionally graded materials, and heterogeneous materials with a periodic microstructure. To design and manufacture the components made of these materials, the computer models for representing them need first to be built so that further analysis, optimization and manufacturing can be implemented based on the models. This paper develops such a modeling method, which can be implemented by employing the functions of current CAD graphic software and obtain the model that includes all the material information (about periodic microstructures, constituent composition, inclusions, and embedded parts) along with geometry information in 3D solid modeling without the problem arising from too much data.  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