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   278800篇
  免费   3336篇
  国内免费   1305篇
电工技术   4802篇
综合类   519篇
化学工业   40394篇
金属工艺   11133篇
机械仪表   8427篇
建筑科学   6425篇
矿业工程   1575篇
能源动力   6979篇
轻工业   22991篇
水利工程   3036篇
石油天然气   5784篇
武器工业   43篇
无线电   33499篇
一般工业技术   56518篇
冶金工业   50901篇
原子能技术   7489篇
自动化技术   22926篇
  2021年   2152篇
  2019年   2064篇
  2018年   3574篇
  2017年   3673篇
  2016年   3902篇
  2015年   2484篇
  2014年   4346篇
  2013年   12141篇
  2012年   7066篇
  2011年   9704篇
  2010年   7536篇
  2009年   8755篇
  2008年   9105篇
  2007年   9142篇
  2006年   7812篇
  2005年   7255篇
  2004年   7215篇
  2003年   6981篇
  2002年   6722篇
  2001年   6847篇
  2000年   6480篇
  1999年   6771篇
  1998年   16314篇
  1997年   11602篇
  1996年   8935篇
  1995年   6864篇
  1994年   6037篇
  1993年   6079篇
  1992年   4408篇
  1991年   4202篇
  1990年   4084篇
  1989年   4076篇
  1988年   3784篇
  1987年   3416篇
  1986年   3415篇
  1985年   3758篇
  1984年   3475篇
  1983年   3241篇
  1982年   3042篇
  1981年   3056篇
  1980年   3041篇
  1979年   2843篇
  1978年   2890篇
  1977年   3159篇
  1976年   4108篇
  1975年   2433篇
  1974年   2405篇
  1973年   2409篇
  1972年   2028篇
  1971年   1789篇
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
1.
2.
The use of field robots can greatly decrease the amount of time, effort, and associated risk compared to if human workers were to carryout certain tasks such as disaster response. However, transportability and reliability remain two main issues for most current robot systems. To address the issue of transportability, we have developed a lightweight modularizable platform named AeroArm. To address the issue of reliability, we utilize a multimodal sensing approach, combining the use of multiple sensors and sensor types, and the use of different detection algorithms, as well as active continuous closed‐loop feedback to accurately estimate the state of the robot with respect to the environment. We used Challenge 2 of the 2017 Mohammed Bin Zayed International Robotics Competition as an example outdoor manipulation task, demonstrating the capabilities of our robot system and approach in achieving reliable performance in the fields, and ranked fifth place internationally in the competition.  相似文献   
3.

Stability constants and formation enthalpies of supramolecular complexes of crown ethers and their cyclic and acyclic analogues are determined on the basis of experimental data obtained by different physicochemical methods in the terms of a general approach developed and implemented in the ChemEqui software package. The established regularities of variation of stability of complexes are discussed as dependent on the ligand structure, nature of the cation, solvent, and anion. The applicability of the suggested method of determining complexation selectivity is shown for multicomponent equilibria in solutions.

  相似文献   
4.
Lobster krill (Munida genus) represents an under‐valued crustacean frequently caught on European fishing banks. In this work, its sensory, microbiological and biochemical qualities were evaluated during chilled storage. Additionally, the effects of a prestorage antimelanosic treatment consisting of soaking in sodium metabisulphite (SMB) solutions at two different concentrations (0.25% and 0.75%) were also studied. SMB prestorage treatment provided lobster specimens that still exhibited acceptable sensory quality after 10 days of storage, while control specimens were unacceptable at that time. SMB treatment also resulted in a significant (P < 0.05) inhibition of microbial growth, mainly of Enterobacteriaceae, psychrotrophes and proteolytic bacteria. Low lipid oxidation levels were observed for all batches; however, a significantly higher (P < 0.05) retention of polyunsaturated fatty acids was found in SMB‐treated lobster, especially in the 0.75% SMB batch. The results presented here open the way to the potential commercialisation of currently under‐utilised lobster krill as a chilled product.  相似文献   
5.
6.
7.
8.
9.
10.
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