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   6721篇
  免费   180篇
  国内免费   37篇
电工技术   94篇
综合类   13篇
化学工业   1494篇
金属工艺   238篇
机械仪表   181篇
建筑科学   92篇
矿业工程   18篇
能源动力   464篇
轻工业   362篇
水利工程   52篇
石油天然气   13篇
无线电   880篇
一般工业技术   1601篇
冶金工业   793篇
原子能技术   51篇
自动化技术   592篇
  2024年   15篇
  2023年   79篇
  2022年   157篇
  2021年   261篇
  2020年   165篇
  2019年   167篇
  2018年   256篇
  2017年   159篇
  2016年   183篇
  2015年   146篇
  2014年   214篇
  2013年   412篇
  2012年   278篇
  2011年   368篇
  2010年   292篇
  2009年   286篇
  2008年   255篇
  2007年   219篇
  2006年   201篇
  2005年   160篇
  2004年   130篇
  2003年   148篇
  2002年   102篇
  2001年   106篇
  2000年   102篇
  1999年   120篇
  1998年   259篇
  1997年   155篇
  1996年   145篇
  1995年   99篇
  1994年   114篇
  1993年   112篇
  1992年   87篇
  1991年   95篇
  1990年   76篇
  1989年   62篇
  1988年   56篇
  1987年   69篇
  1986年   68篇
  1985年   49篇
  1984年   68篇
  1983年   61篇
  1982年   49篇
  1981年   32篇
  1980年   47篇
  1979年   50篇
  1978年   31篇
  1977年   33篇
  1976年   45篇
  1973年   19篇
排序方式: 共有6938条查询结果,搜索用时 0 毫秒
1.
Wireless Personal Communications - The ongoing technological developments have totally transformed the lives of human beings. With the emergence of the smart era and the smart city concept, a few...  相似文献   
2.
3.
4.
The custom design of protein–dendron amphiphilic macromolecules is at the forefront of macromolecular engineering. Macromolecules with this architecture are very interesting because of their ability to self-assemble into various biomimetic nanoscopic structures. However, to date, there are no reports on this concept due to technical challenges associated with the chemical synthesis. Towards that end, herein, a new chemical methodology for the modular synthesis of a suite of monodisperse, facially amphiphilic, protein–dendron bioconjugates is reported. Benzyl ether dendrons of different generations (G1–G4) are coupled to monodisperse cetyl ethylene glycol to form macromolecular amphiphilic activity-based probes (AABPs) with a single protein reactive functionality. Micelle-assisted protein labeling technology is utilized for site-specific conjugation of macromolecular AABPs to globular proteins to make monodisperse, facially amphiphilic, protein–dendron bioconjugates. These biohybrid conjugates have the ability to self-assemble into supramolecular protein nanoassemblies. Self-assembly is primarily mediated by strong hydrophobic interactions of the benzyl ether dendron domain. The size, surface charge, and oligomeric state of protein nanoassemblies could be systematically tuned by choosing an appropriate dendron or protein of interest. This chemical method discloses a new way to custom-make monodisperse, facially amphiphilic, protein–dendron bioconjugates.  相似文献   
5.
6.
Multimedia Tools and Applications - Facial expression is the most common technique is used to convey the expressions of human beings. Due to different ethnicity and age, faces differ from one...  相似文献   
7.
Hydrogen fuel is a promising alternative to fossil fuels because of its energy content, clean nature, and fuel efficiency. However, it is not readily available. Most current producion processes are very energy intensive and emit carbon dioxide. Therefore, this article reviews technological options for hydrogen production that are eco-friendly and generate clean hydrogen fuel. Biological methods, such different fermentation processes and photolysis are discussed together with the required substrates and the process efficiency.  相似文献   
8.
9.
Multimedia Tools and Applications - Rapid advancement in technology has led to the use of biometric authentication in every field. In particular, from the past few years, iris recognition systems...  相似文献   
10.
2-D symmetry: theory and filter design applications   总被引:1,自引:0,他引:1  
In this comprehensive review article, we present the theory of symmetry in two-dimensional (2-D) filter functions and in 2-D Fourier transforms. It is shown that when a filter frequency response possesses symmetry, the realization problem becomes relatively simple. Further, when the frequency response has no symmetry, there is a technique to decompose that frequency response into components each of which has the desired symmetry. This again reduces the complexity of two-dimensional filter design. A number of filter design examples are illustrated.  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