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   277993篇
  免费   3330篇
  国内免费   1304篇
电工技术   4803篇
综合类   519篇
化学工业   40264篇
金属工艺   11125篇
机械仪表   8417篇
建筑科学   6401篇
矿业工程   1575篇
能源动力   6966篇
轻工业   22469篇
水利工程   3035篇
石油天然气   5782篇
武器工业   43篇
无线电   33505篇
一般工业技术   56465篇
冶金工业   50934篇
原子能技术   7490篇
自动化技术   22834篇
  2021年   2152篇
  2019年   2062篇
  2018年   3577篇
  2017年   3672篇
  2016年   3899篇
  2015年   2484篇
  2014年   4345篇
  2013年   11959篇
  2012年   7063篇
  2011年   9703篇
  2010年   7529篇
  2009年   8745篇
  2008年   9091篇
  2007年   9137篇
  2006年   7802篇
  2005年   7246篇
  2004年   7203篇
  2003年   6978篇
  2002年   6718篇
  2001年   6844篇
  2000年   6478篇
  1999年   6763篇
  1998年   16325篇
  1997年   11583篇
  1996年   8925篇
  1995年   6848篇
  1994年   6015篇
  1993年   6056篇
  1992年   4403篇
  1991年   4184篇
  1990年   4078篇
  1989年   4061篇
  1988年   3752篇
  1987年   3388篇
  1986年   3393篇
  1985年   3745篇
  1984年   3460篇
  1983年   3218篇
  1982年   3025篇
  1981年   3040篇
  1980年   3031篇
  1979年   2832篇
  1978年   2870篇
  1977年   3144篇
  1976年   4103篇
  1975年   2418篇
  1974年   2379篇
  1973年   2397篇
  1972年   2019篇
  1971年   1782篇
排序方式: 共有10000条查询结果,搜索用时 15 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