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   77702篇
  免费   9631篇
  国内免费   7559篇
电工技术   7147篇
技术理论   14篇
综合类   8294篇
化学工业   1636篇
金属工艺   718篇
机械仪表   3877篇
建筑科学   3144篇
矿业工程   2008篇
能源动力   1103篇
轻工业   1063篇
水利工程   1756篇
石油天然气   3042篇
武器工业   890篇
无线电   13082篇
一般工业技术   3282篇
冶金工业   1296篇
原子能技术   779篇
自动化技术   41761篇
  2024年   406篇
  2023年   1079篇
  2022年   2157篇
  2021年   2679篇
  2020年   2895篇
  2019年   2208篇
  2018年   1983篇
  2017年   2473篇
  2016年   2776篇
  2015年   3169篇
  2014年   5745篇
  2013年   4943篇
  2012年   6106篇
  2011年   6597篇
  2010年   5026篇
  2009年   4999篇
  2008年   5504篇
  2007年   6130篇
  2006年   5189篇
  2005年   4591篇
  2004年   3867篇
  2003年   3281篇
  2002年   2380篇
  2001年   1783篇
  2000年   1480篇
  1999年   1031篇
  1998年   768篇
  1997年   634篇
  1996年   528篇
  1995年   462篇
  1994年   367篇
  1993年   262篇
  1992年   189篇
  1991年   184篇
  1990年   139篇
  1989年   114篇
  1988年   91篇
  1987年   70篇
  1986年   63篇
  1985年   101篇
  1984年   72篇
  1983年   83篇
  1982年   67篇
  1981年   40篇
  1980年   23篇
  1979年   36篇
  1978年   13篇
  1977年   20篇
  1976年   14篇
  1959年   8篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
1.
探索采用数据可视化技术分析儿童用品TBT通报数据,以可视化图形图像呈现通报热点并揭示趋势信息,提出对策与建议,助力为儿童用品产业升级、TBT预警数据分析和信息传播工作提供新思路,提高中小企业的国外市场准入机会。  相似文献   
2.
本文以云杉八齿小蠹Ips typographus Linnaeus为例,经标本选取,观察虫体整体形态,绘制整体结构草图,电子显微镜观察局部、得到局部数字图像,分别建立虫体每一部分的高精度细节。把模型每部分拼装在一起组成整体模型,构建出了云杉八齿小蠹三维虚拟昆虫数字化模型。  相似文献   
3.
4.
Private information retrieval(PIR) is an important privacy protection issue of secure multi-party computation, but the PIR protocols based on classical cryptography are vulnerable because of new technologies,such as quantum computing and cloud computing. The quantum private queries(QPQ) protocols available, however, has a high complexity and is inefficient in the face of large database. This paper, based on the QKD technology which is mature now, proposes a novel QPQ protocol utilizing the key dilution and auxiliary parameter. Only N quits are required to be sent in the quantum channel to generate the raw key, then the straight k bits in the raw key are added bitwise to dilute the raw key, and a final key is consequently obtained to encrypt the database. By flexible adjusting of auxiliary parameters θ and k, privacy is secured and the query success ratio is improved. Feasibility and performance analyses indicate that the protocol has a high success ratio in first-trial query and is easy to implement, and that the communication complexity of O(N) is achieved.  相似文献   
5.
6.
本文对运营商信息安全集中管控架构演进和信息安全管控策略面临的问题进行了深入分析,提出了信息安全集中管控架构的演进方向建议及对信息安全监控策略工作优化的若干意见。  相似文献   
7.
Process object is the instance of process. Vertexes and edges are in the graph of process object. There are different types of the object itself and the associations between object. For the large-scale data, there are many changes reflected. Recently, how to find appropriate real-time data for process object becomes a hot research topic. Data sampling is a kind of finding c hanges o f p rocess o bjects. There i s r equirements f or s ampling to be adaptive to underlying distribution of data stream. In this paper, we have proposed a adaptive data sampling mechanism to find a ppropriate d ata t o m odeling. F irst o f all, we use concept drift to make the partition of the life cycle of process object. Then, entity community detection is proposed to find changes. Finally, we propose stream-based real-time optimization of data sampling. Contributions of this paper are concept drift, community detection, and stream-based real-time computing. Experiments show the effectiveness and feasibility of our proposed adaptive data sampling mechanism for process object.  相似文献   
8.
For rechargeable wireless sensor networks, limited energy storage capacity, dynamic energy supply, low and dynamic duty cycles cause that it is unpractical to maintain a fixed routing path for packets delivery permanently from a source to destination in a distributed scenario. Therefore, before data delivery, a sensor has to update its waking schedule continuously and share them to its neighbors, which lead to high energy expenditure for reestablishing path links frequently and low efficiency of energy utilization for collecting packets. In this work, we propose the maximum data generation rate routing protocol based on data flow controlling technology. For a sensor, it does not share its waking schedule to its neighbors and cache any waking schedules of other sensors. Hence, the energy consumption for time synchronization, location information and waking schedule shared will be reduced significantly. The saving energy can be used for improving data collection rate. Simulation shows our scheme is efficient to improve packets generation rate in rechargeable wireless sensor networks.  相似文献   
9.
机载光电雷达受平台及大气环境影响较大,而它机试飞能有效规避研制风险,是产品研制的必经阶段。本文介绍了机载光电雷达它机试飞试验系统组成、试验流程和数据处理等内容。经工程验证,实施过程满足任务需求,对其他光电系统的它机及本机试飞具有参考价值。  相似文献   
10.
The motivation of this work is to address real-time sequential inference of parameters with a full Bayesian formulation. First, the proper generalized decomposition (PGD) is used to reduce the computational evaluation of the posterior density in the online phase. Second, Transport Map sampling is used to build a deterministic coupling between a reference measure and the posterior measure. The determination of the transport maps involves the solution of a minimization problem. As the PGD model is quasi-analytical and under a variable separation form, the use of gradient and Hessian information speeds up the minimization algorithm. Eventually, uncertainty quantification on outputs of interest of the model can be easily performed due to the global feature of the PGD solution over all coordinate domains. Numerical examples highlight the performance of the method.  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