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   5716篇
  免费   491篇
  国内免费   271篇
电工技术   344篇
综合类   550篇
化学工业   973篇
金属工艺   351篇
机械仪表   401篇
建筑科学   318篇
矿业工程   288篇
能源动力   156篇
轻工业   310篇
水利工程   103篇
石油天然气   289篇
武器工业   43篇
无线电   637篇
一般工业技术   601篇
冶金工业   257篇
原子能技术   54篇
自动化技术   803篇
  2024年   20篇
  2023年   57篇
  2022年   109篇
  2021年   160篇
  2020年   105篇
  2019年   115篇
  2018年   132篇
  2017年   131篇
  2016年   163篇
  2015年   193篇
  2014年   255篇
  2013年   230篇
  2012年   271篇
  2011年   294篇
  2010年   285篇
  2009年   324篇
  2008年   363篇
  2007年   274篇
  2006年   277篇
  2005年   231篇
  2004年   232篇
  2003年   357篇
  2002年   471篇
  2001年   460篇
  2000年   231篇
  1999年   216篇
  1998年   110篇
  1997年   85篇
  1996年   70篇
  1995年   63篇
  1994年   53篇
  1993年   32篇
  1992年   39篇
  1991年   15篇
  1990年   13篇
  1989年   9篇
  1988年   10篇
  1987年   2篇
  1986年   4篇
  1985年   4篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1981年   7篇
  1980年   3篇
排序方式: 共有6478条查询结果,搜索用时 15 毫秒
21.
This paper studies the analysis of parametric stability and decentralized state feedback control of a kind of quantized interconnected systems. The output of each controller is quantized logarithmically before it is input to the subsystem, and the quantized density would affect the stability of the systems. First, a decentralized state feedback controller is designed for interconnected systems without quantization and the corresponding stable region is obtained. Second, for a given controller, the lower bound of the quantization density is evaluated from parameters of local controllers. Finally, the proposed method is applied to coupled inverted pendulums systems which can be viewed as quantized interconnected systems. The simulation results show that by using the proposed quantized controllers, the interconnected inverted pendulum systems are parametrically stabilized.  相似文献   
22.
Interaction and communication between humans with smart mobile devices are a new trend of development in Internet of Things (IoT). With the powerful sensing capability of smart device and human mobility, various services could be provided by building a trusted chain between service requesters and suppliers. The cognition of social relations between mobile nodes is the basis of final mobile-aware services. It involves many decision factors, such as time, space and activity patterns. Using social network theory, a new cognitive model for social relations of mobile nodes in IoT is proposed. Firstly, nodes' social relations are reasoned and quantified from multiple perspectives based on the summary of social characteristics of mobile nodes and the definition of different decision factors. Then the location factor, interconnection factor, service evaluation factor and feedback aggregation factor are defined to solve the shortcomings in existing quantitative models. Finally, the weight distribution is set up by information entropy and rough set theory for these decision factors; it can overcome the shortage of traditional methods, in which the weight is set up by subjective ways and hence their dynamic adaptability is poor. We compare our cognitive model to existing models using MIT dataset by defining a variety of test indicators, such as network overall density (NOD), the degree center potential (DCP), the network distribution index (EI), etc. Simulation results show that, the cognitive model has better internal structure and significant validity in network analysis, and thus can provide mobile-aware service effectively in dynamic environment.  相似文献   
23.
工学结合在高职计算机专业教学改革中的研究   总被引:1,自引:0,他引:1  
"工学结合,校企合作"是中国这几年来职业教育发展进程中最具特色、最突出的办学经验,笔者结合自己实际教学,从教学面临的问题、解决方案、取得的成效等方面提出了一些具体的改进措施和建议,以促进和加强计算机专业学生的职业能力和职业素质的培养。  相似文献   
24.
研究基于分布式算法的数字滤波器设计方法,介绍了能高效实现固定常数乘法的分布式算法原理,并将分布式算法应用于FIR低通滤波器设计,实现了16阶滤波器的设计和调试.采用了EP3C25F324C8来完成滤波器的设计,其中采用串行加法器将数据进行预相加,将16阶降为8阶,降低了资源占用率并提升了处理速度.使用Matlab编程8阶固定常数系数对应256个值的查找表直接导入到FPGA的ROM中,设计方法具有兼容性,可设计更高阶次的滤波器.通过功能仿真证明,方法可行高效.  相似文献   
25.
消费社会的发展,促使现代产业形态从单一的生产,到设计、生产、营销的换代升级迅速转型。产品与服务更新,不再是现有思路与工艺水平的简单重复,创意成为新一轮产品更新的重要竞争力,艺术设计深入到了文化创意层面,创意产业发展对设计人才培养提出新的要求。加强个性化想象艺术素养与实践能力的培育,构建以创造能量培养为核心的教育理念和教学模式,成为设计教育关注的焦点。  相似文献   
26.
抽取动态异构Web信息以建立索引数据库供用户统一检索使用,是高校图书馆资源整合中的技术难点.通过对目标WEB站点表单提交方式和查询参数的研究和分析,使用Http模拟Post提交查询参数获得检索结果页面,基于开源项目HTMLParser包,以抽取CNKI文章检索结果入库为例,给出了算法及其实现的详细过程.  相似文献   
27.
With the development of organic solar cells (OSCs), the high-performance and stable batch variance are becoming a new challenge for designing polymer donors. To obtain high photovoltaic performance, adopting polymers with high molecular weight as donors is an ordinary strategy. However, the high molecular weight need to subtly control the reaction time and state, inevitably caused batch-to-batch variations. Herein, a strategy of steric effect is applied to benzodifuran (BDF)-based polymer by introducing different positions of Cl atom, producing two polymers PBDFCl-1 and PBDFCl-2. The more twisted side chains conformation not only achieve the control of moderate molecular weight for PBDFCl-2, but also easily form molecular stacking through adopting BDF unit and maintain sufficient polymeric crystallinity. Due to the optimized stacking mode and good blend miscibility, PBDFCl-2-based device exhibitsa more elegant power conversion efficiency (PCE) of 17.00% compared to PBDFCl-1-based device. This is the highest efficiency record for BDF-based binary OSCs. Meanwhile, the PCE device variation of the different molecular weights for PBDFCl-2 is little, indicating the reduction of the batch variation. Therefore, smartly using steric effect of Cl atom in strong crystalline BDF unit can form efficient molecular stacking regulations and realize the coordination of high-performance and stable batch variance.  相似文献   
28.
未来的战争必将是多兵种、多域联合作战,战场态势作为未来联合作战的重要支撑,旨在为联合作战提供精准、高效的统一态势图,而如何将多平台、同/异构传感器信息及其他情报信息与战场环境融合生成准确可靠的战场态势是亟需解决的技术难题。鉴于现代海战场对高精度、强实时、全要素战场态势图的迫切需求,对海战场态势生成技术进行了综述。首先梳理了海上态势生成项目的发展历程及能力水平;然后详细介绍了通用作战图/通用战术图等典型项目,在态势生成部分中通过态势图的要素组成、态势生成流程及关键技术对态势生成技术进行了阐述;最后对未来海战场态势生成技术的发展趋势进行了预测,希望可以为态势生成相关研究提供参考。  相似文献   
29.
Wang  Ling  Gui  Lingpeng  Zhu  Hui 《Applied Intelligence》2022,52(2):1389-1405

Traditional temporal association rules mining algorithms cannot dynamically update the temporal association rules within the valid time interval with increasing data. In this paper, a new algorithm called incremental fuzzy temporal association rule mining using fuzzy grid table (IFTARMFGT) is proposed by combining the advantages of boolean matrix with incremental mining. First, multivariate time series data are transformed into discrete fuzzy values that contain the time intervals and fuzzy membership. Second, in order to improve the mining efficiency, the concept of boolean matrices was introduced into the fuzzy membership to generate a fuzzy grid table to mine the frequent itemsets. Finally, in view of the Fast UPdate (FUP) algorithm, fuzzy temporal association rules are incrementally mined and updated without repeatedly scanning the original database by considering the lifespan of each item and inheriting the information from previous mining results. The experiments show that our algorithm provides better efficiency and interpretability in mining temporal association rules than other algorithms.

  相似文献   
30.
OBJECTIVE: To determine whether the recently published guidelines on neuroimaging in patients with new-onset seizures are applicable to children. METHODS: We carried out a retrospective analysis of 107 neurologically normal children (excluding children with simple febrile seizures) who had undergone neuroimaging when they presented to the emergency department with a possible "first seizure." RESULTS: Eight of the 107 children had nonepileptic events (gastroesophageal reflux, syncopal event, rigor). Of the remaining 99 children, 49 had provoked seizures (complicated febrile seizure, meningo-encephalitis, toxic or metabolic abnormalities), and 50 had unprovoked seizures. A total of 19 children had brain abnormalities identified on computed tomography (CT) scan; 7 received further investigation or intervention as a result of CT scan findings (2 with tumors, 3 with vascular anomalies, 1 with cysticercosis, and 1 with obstructive hydrocephalus). CT scan abnormalities requiring treatment or monitoring were more frequently seen in children with their first unprovoked seizure (P < .01) and in those children whose seizure onset had been focal or who had focal abnormalities identified on postictal neurologic examination (P < .04). CONCLUSION: In a child, a seizure in the setting of a fever rarely indicates the presence of an unexpected CT scan lesion requiring intervention.  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