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   232279篇
  免费   17784篇
  国内免费   9874篇
电工技术   12682篇
技术理论   10篇
综合类   15343篇
化学工业   37444篇
金属工艺   13637篇
机械仪表   14361篇
建筑科学   14434篇
矿业工程   5436篇
能源动力   5442篇
轻工业   15046篇
水利工程   4539篇
石油天然气   12084篇
武器工业   1585篇
无线电   25342篇
一般工业技术   33527篇
冶金工业   13665篇
原子能技术   5738篇
自动化技术   29622篇
  2024年   724篇
  2023年   2828篇
  2022年   5618篇
  2021年   8030篇
  2020年   6041篇
  2019年   5238篇
  2018年   6443篇
  2017年   7056篇
  2016年   6633篇
  2015年   7858篇
  2014年   10367篇
  2013年   12684篇
  2012年   14146篇
  2011年   15197篇
  2010年   13424篇
  2009年   13189篇
  2008年   13070篇
  2007年   12375篇
  2006年   11721篇
  2005年   9944篇
  2004年   7835篇
  2003年   7420篇
  2002年   7965篇
  2001年   7156篇
  2000年   5667篇
  1999年   4676篇
  1998年   3508篇
  1997年   2946篇
  1996年   2629篇
  1995年   2310篇
  1994年   1877篇
  1993年   1546篇
  1992年   1455篇
  1991年   1262篇
  1990年   1246篇
  1989年   1103篇
  1988年   983篇
  1987年   902篇
  1986年   783篇
  1985年   755篇
  1984年   730篇
  1981年   685篇
  1979年   750篇
  1978年   785篇
  1977年   751篇
  1976年   770篇
  1975年   719篇
  1974年   725篇
  1973年   726篇
  1972年   707篇
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
101.
102.
本文提出了一种基于分散加载技术实现Boot程序和用户应用程序在同一个工程编写开发的固件更新方法 .通过编写分散加载规范文件在工程中实现代码存储区分区.为了保证固件更新的稳定性和可靠性,在固件下载过程中引入CRC校验、丢包错包重传等容错技术.实验结果 验证了方法的有效性和可靠性.  相似文献   
103.
104.
105.
106.
Russian Engineering Research - Thin-film vacuum technology permits the creation of new electrode materials on the basis of a flexible carbon matrix with a highly developed surface. Supercapacitor...  相似文献   
107.
Anti-washout and tissue adhesion properties are essential for the clinical application of injectable bone materials. In this study, we prepared calcium phosphate cement (CPC) with anti-washout and tissue adhesion properties and attempted to build covalent bonds between CPC and the amino groups in bone tissue under a self-regulating pH system in the CPC (acidic to basic). The results of push-out tests demonstrated that a significant enhancement (from 6.42 ± 0.76 N to 61.5 ± 4.09 N) in tissue adhesion was obtained with the addition of 6% (w/w) oxidized sodium alginate (OSA) in CPC. The FTIR, XRD, anti-washout test, XPS, pH test, and SEM results suggested that the synergistic effect of OSA-citric acid (CA) led to the formation of a three-dimensional gel network structure in the CPC, and the Schiff base reaction between aldehyde and amino groups induced adhesion between CPC and the bone tissue. Further, the addition of less OSA had no significant negative effect on the hydration properties of CPC. Our work aims to promote the development of injectable bone material in clinical applications.  相似文献   
108.
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   
109.
Refractories and Industrial Ceramics - Results of studying the rheotechnological properties of moldable refractory mixes based on bauxite suspensions plasticized with refractory clay are presented....  相似文献   
110.
How to improve the sensitivity of the temperature-sensing luminescent materials is one of the most important objects currently. In this work, to obtain high sensitivity and learn the corresponding mechanism, the rare earth (RE) ions doped Y4.67Si3O13 (YS) phosphors were developed by solid-state reaction. The phase purity, structure, morphology and luminescence characteristics were evaluated by XRD, TEM, emission spectra, etc. The change of the optical bandgaps between the host and RE-doped phosphors was found, agreeing with the calculation results based on density-functional theory. The temperature-dependence of the upconversion (UC) luminescence revealed that a linear relationship exists between the fluorescence intensity ratio of Ho3+ and temperature. The theoretical resolution was evaluated. High absolute (0.083 K−1) and relative (3.53% K−1 at 293 K) sensitivities have been gained in the YS:1%Ho3+, 10%Yb3+. The effect of the Yb3+ doping concentration and pump power on the sensitivities was discussed. The pump-power–dependence of the UC luminescence indicated the main mechanism for high sensitivities in the YS:1%Ho3+, 10%Yb3+. Moreover, the decay-lifetime based temperature sensing was also evaluated. The above results imply that the present phosphors could be promising candidates for temperature sensors, and the proposed strategies are instructive in exploring other new temperature sensing luminescent materials.  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