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   638534篇
  免费   12868篇
  国内免费   4289篇
电工技术   14390篇
技术理论   2篇
综合类   4081篇
化学工业   93336篇
金属工艺   29147篇
机械仪表   22949篇
建筑科学   17457篇
矿业工程   4102篇
能源动力   16751篇
轻工业   52172篇
水利工程   7059篇
石油天然气   12787篇
武器工业   504篇
无线电   72022篇
一般工业技术   124660篇
冶金工业   112384篇
原子能技术   12202篇
自动化技术   59686篇
  2022年   4474篇
  2021年   7139篇
  2020年   5201篇
  2019年   6017篇
  2018年   15594篇
  2017年   15996篇
  2016年   13150篇
  2015年   8034篇
  2014年   11959篇
  2013年   27760篇
  2012年   20082篇
  2011年   30394篇
  2010年   25383篇
  2009年   26507篇
  2008年   26589篇
  2007年   27742篇
  2006年   18728篇
  2005年   19686篇
  2004年   17079篇
  2003年   16482篇
  2002年   15041篇
  2001年   14629篇
  2000年   13435篇
  1999年   13904篇
  1998年   34351篇
  1997年   24137篇
  1996年   18561篇
  1995年   13764篇
  1994年   11924篇
  1993年   11462篇
  1992年   8283篇
  1991年   7745篇
  1990年   7460篇
  1989年   7233篇
  1988年   6628篇
  1987年   5868篇
  1986年   5731篇
  1985年   6329篇
  1984年   5947篇
  1983年   5209篇
  1982年   4934篇
  1981年   4999篇
  1980年   4726篇
  1979年   4620篇
  1978年   4413篇
  1977年   5340篇
  1976年   6988篇
  1975年   3804篇
  1974年   3557篇
  1973年   3674篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Journal of Computer and Systems Sciences International - It is shown that the Lyapunov theorem on the distribution properties of the sum of random variables with different distribution densities...  相似文献   
5.
Multimedia Tools and Applications - Mammograms are the images used by radiologists to diagnose breast cancer. Breast cancer is one of the most common cancers in women. The early detection of breast...  相似文献   
6.
Polymer electrets have revealed great potential application in electromechanical devices because of the low weight, large quasi-piezoelectric sensitivity, and excellent flexibility. For an electret, a permanent and macroscopic electric field exists on the surface, principally led by a macroscopic electrostatic charge on the surface or a net orientation of polar groups inside the object. Here, progress in the development of polymer electrets is reviewed. After a brief retrospect of the research courses and those typical polymer electrets that are classified into fluorine polymer and nonfluorine polymer, we present a survey on the charging methods, including corona, soft X-ray, contact, thermal and monoenergetic particle beams. The latest representative applications (i.e., power harvesting, sensors, field effect transistors, and biomedicine) based on polymer electrets are also summarized. Finally, we complete this review with a discussion on perspectives and challenges in this field.  相似文献   
7.
Refractories and Industrial Ceramics - The paper introduces a promising technology for utilizing a traditional scheme for implementing a flow-through micro-arc oxidation method to restore localized...  相似文献   
8.
Multimedia Tools and Applications - Recently, many concepts in technology has been changed. According to the digital transformation trends, Internet of Things (IoT) represents an interested...  相似文献   
9.
Ceramic microparticles have great potentials in various fields such as materials engineering, biotechnology, microelectromechanical systems, etc. Morphology of the microparticle performs an important role on their application. To date, it remains difficult to find an effective and controllable way for fabricating nonspherical ceramic microparticles with 3D features. This work demonstrates a method that combines UV light lithography and single emulsion opaque-droplet-templated microfluidic molding to prepare the crescent-shaped ceramic microparticles. By tailoring the intensity of UV light and flow rate of fluid, the shapes of microparticles are accordingly tuned. Therefore, varieties of crescent-shaped microparticles and their variations have been fabricated. After sintering, the crescent-shaped alumina ceramic microparticles were obtained. Benefitting from the light absorption and scattering behavior of most ceramic nanoparticles, this system can serve as a general platform to produce crescent-shaped microparticles made from different materials, and hold great potentials for applications in microrobotics, structural materials in MEMS, and biotechnology.  相似文献   
10.
Multimedia Tools and Applications - The three-dimensional models of brain tumors serve as diagnostic assistance for physicians, surgeons, and radiologists. The proposed system establishes an...  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