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   6078篇
  免费   826篇
  国内免费   694篇
电工技术   511篇
综合类   799篇
化学工业   148篇
金属工艺   264篇
机械仪表   233篇
建筑科学   1301篇
矿业工程   92篇
能源动力   56篇
轻工业   39篇
水利工程   63篇
石油天然气   95篇
武器工业   35篇
无线电   908篇
一般工业技术   414篇
冶金工业   196篇
原子能技术   25篇
自动化技术   2419篇
  2024年   25篇
  2023年   92篇
  2022年   173篇
  2021年   192篇
  2020年   217篇
  2019年   202篇
  2018年   183篇
  2017年   215篇
  2016年   221篇
  2015年   357篇
  2014年   506篇
  2013年   460篇
  2012年   588篇
  2011年   573篇
  2010年   456篇
  2009年   452篇
  2008年   435篇
  2007年   478篇
  2006年   359篇
  2005年   273篇
  2004年   197篇
  2003年   183篇
  2002年   135篇
  2001年   147篇
  2000年   100篇
  1999年   67篇
  1998年   68篇
  1997年   46篇
  1996年   34篇
  1995年   32篇
  1994年   25篇
  1993年   26篇
  1992年   22篇
  1991年   13篇
  1990年   10篇
  1989年   6篇
  1988年   7篇
  1987年   4篇
  1986年   4篇
  1984年   4篇
  1983年   3篇
  1981年   2篇
  1980年   3篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
排序方式: 共有7598条查询结果,搜索用时 15 毫秒
1.
针对现有海量点云可视化方法存在索引构建时间长、内存占用大等问题,研究一种八叉树索引结合OSG分页结点的快速可视化方法,可在占用较小内存的基础上快速建立点云索引并实时调度。采用八叉树索引结构对海量点云进行数据组织,建立各层级的八叉树结点并以文件映射的方式分块保存,对结点文件重组织转换为支持OSG渲染引擎的多分辨率点云数据。采用基于OSG分页结点的实时调度技术,对海量点云进行高质量可视化。与目前两款主流的点云数据处理商业软件进行实验对比分析,结果表明所提方法具有索引建立速度快、内存占用小等优点,同时可视化交互更加流畅,适用于各种配置计算机下海量点云数据的调度管理与实时可视化。  相似文献   
2.
3.
Attribute Allocation and Retrieval Scheme for Large-Scale Sensor Networks   总被引:1,自引:0,他引:1  
Wireless sensor network is an emerging technology that enables remote monitoring of large geographical regions. In this paper, we address the problem of distributing attributes over such a large-scale sensor network so that the cost of data retrieval is minimized. The proposed scheme is a data-centric storage scheme where the attributes are distributed over the network depending on the correlations between them. The problem addressed here is similar to the Allocation Problem of distributed databases. In this paper, we have defined the Allocation Problem in the context of sensor networks and have proposed a scheme for finding a good distribution of attributes to the sensor network. We also propose an architecture for query processing given such a distribution of attributes. We analytically determine the conditions under which the proposed architecture is beneficial and present simulation results to demonstrate the same. To the best of our knowledge, this is the first attempt to determine an allocation of attributes over a sensor network based on the correlations between attributes.  相似文献   
4.
超媒体系统中的人工智能方法   总被引:3,自引:0,他引:3  
一、什么是超媒体近年来迅速崛起的多媒体(multimedia)技术,是一种使计算机具有交互式地综合处理和管理文字、图形、图象、声音、视频等多种媒体能力的技术,必将使计算机技术发生一  相似文献   
5.
寒区沥青胶浆延性研究   总被引:3,自引:0,他引:3  
首交提出了沥青胶浆延工的概念,并测定、分析了两种寒区沥青、四种粉胶比在四个温度下的沥青胶浆延度。认为沥青胶浆延度较沥青延度更能反映沥青混合料的流变性能,而且胶浆延度与温度、粉胶比之间有很好的相关性。  相似文献   
6.
Gleeble 3800热模拟试验机在宝钢的典型应用与功能开发   总被引:4,自引:0,他引:4  
热模拟试验可研究成分与各工艺参数对组织和性能的影响,用于指导产品设计和实际生产工艺的制定,还有助于建立数学模型。文章介绍了Gleeble 3800热/力模拟试验机在宝钢实际应用中的几个典型试验,包括高温热塑性试验、多道次变形试验、冷轧薄板相转变点试验和HAZ焊接热影响区热模拟试验等。这些试验可用来解决连铸、轧钢和冷轧产品热处理生产中存在的一些问题。  相似文献   
7.
通过分折和研究单层门式刚架轻型钢结构厂房中的吊车梁设计,总结了轻型钢结构吊车梁的设计方法和节点连接构造,对合理设计吊车梁,降低用钢量提出了设计建议。  相似文献   
8.
Polymer modified bitumen (PMB) is used in various construction applications, especially in motorways. The aim of this study is to improve features of 60/70 penetration grade, modified bitumen used on highways. Increasing the sensitivity to temperature and oxidation resistance are very important points for the modified bitumen. This condition was provided by reacting the carboxylic acid groups in asphaltene with the reactive ethylene terpolymer to form ester. Reactive ethylene terpolymer (RETP) and ethylene terpolymer (ETP) manufactured by DuPont USA were used as additives in this study. Infrared Spectrophotometer (IR) graphics and optical pictures of the modified bitumen have been examined. It has been observed that the softening point has increased on the other hand, the penetration and ductility values have decreased according to the test results.  相似文献   
9.
The technical characters of mobile agent (MA) originated in the distributional artificial intelligence domain is introduced. A network management construction based on agent (NMCA) is then proposed. The NMCA structure features are elaborated in detail. A prototype design of NMCA is given by using the jKQML programming. The establishment of NMCA platform will be helpful to reduce the correspondence load of network management and improves the efficiency and the expansion ability of network management systems.  相似文献   
10.
Recently Fourier Transform Infrared (FTIR) spectroscopic imaging has been used as a tool to detect the changes in cellular composition that may reflect the onset of a disease. This approach has been investigated as a mean of monitoring the change of the biochemical composition of cells and providing a diagnostic tool for various human cancers and other diseases. The discrimination between different types of tissue based upon spectroscopic data is often achieved using various multivariate clustering techniques. However, the number of clusters is a common unknown feature for the clustering methods, such as hierarchical cluster analysis, k-means and fuzzy c-means. In this study, we apply a FCM based clustering algorithm to obtain the best number of clusters as given by the minimum validity index value. This often results in an excessive number of clusters being created due to the complexity of this biochemical system. A novel method to automatically merge clusters was developed to try to address this problem. Three lymph node tissue sections were examined to evaluate our new method. These results showed that this approach can merge the clusters which have similar biochemistry. Consequently, the overall algorithm automatically identifies clusters that accurately match the main tissue types that are independently determined by the clinician.  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