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   407508篇
  免费   5040篇
  国内免费   1854篇
电工技术   7469篇
综合类   694篇
化学工业   61443篇
金属工艺   16122篇
机械仪表   12485篇
建筑科学   10190篇
矿业工程   1922篇
能源动力   10332篇
轻工业   36896篇
水利工程   3991篇
石油天然气   6316篇
武器工业   48篇
无线电   50109篇
一般工业技术   80687篇
冶金工业   72075篇
原子能技术   9409篇
自动化技术   34214篇
  2021年   2785篇
  2019年   2766篇
  2018年   4485篇
  2017年   4611篇
  2016年   4965篇
  2015年   3401篇
  2014年   5856篇
  2013年   17653篇
  2012年   9710篇
  2011年   13569篇
  2010年   10543篇
  2009年   12229篇
  2008年   12927篇
  2007年   13216篇
  2006年   11423篇
  2005年   10659篇
  2004年   10529篇
  2003年   10228篇
  2002年   10035篇
  2001年   10136篇
  2000年   9578篇
  1999年   9865篇
  1998年   21906篇
  1997年   16054篇
  1996年   12642篇
  1995年   9952篇
  1994年   8889篇
  1993年   8765篇
  1992年   6735篇
  1991年   6465篇
  1990年   6312篇
  1989年   6287篇
  1988年   5868篇
  1987年   5295篇
  1986年   5263篇
  1985年   5965篇
  1984年   5481篇
  1983年   5114篇
  1982年   4856篇
  1981年   4794篇
  1980年   4675篇
  1979年   4494篇
  1978年   4434篇
  1977年   5018篇
  1976年   6437篇
  1975年   3831篇
  1974年   3660篇
  1973年   3708篇
  1972年   3084篇
  1971年   2781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