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   251457篇
  免费   1718篇
  国内免费   277篇
电工技术   4064篇
综合类   92篇
化学工业   40767篇
金属工艺   15278篇
机械仪表   10150篇
建筑科学   4216篇
矿业工程   3799篇
能源动力   3959篇
轻工业   9778篇
水利工程   4167篇
石油天然气   13336篇
武器工业   28篇
无线电   20350篇
一般工业技术   63405篇
冶金工业   32285篇
原子能技术   11243篇
自动化技术   16535篇
  2021年   2831篇
  2019年   2761篇
  2018年   5483篇
  2017年   5765篇
  2016年   6100篇
  2015年   3080篇
  2014年   5374篇
  2013年   10139篇
  2012年   7368篇
  2011年   8997篇
  2010年   7370篇
  2009年   8166篇
  2008年   8232篇
  2007年   7905篇
  2006年   6410篇
  2005年   5599篇
  2004年   5505篇
  2003年   5335篇
  2002年   5160篇
  2001年   4984篇
  2000年   4967篇
  1999年   4272篇
  1998年   7208篇
  1997年   5852篇
  1996年   4437篇
  1995年   3684篇
  1994年   3443篇
  1993年   3646篇
  1992年   3250篇
  1991年   3388篇
  1990年   3511篇
  1989年   3403篇
  1988年   3308篇
  1987年   3307篇
  1986年   3190篇
  1985年   3349篇
  1984年   3290篇
  1983年   3175篇
  1982年   3031篇
  1981年   3080篇
  1980年   3106篇
  1979年   3305篇
  1978年   3541篇
  1977年   3487篇
  1976年   3947篇
  1975年   3243篇
  1974年   3332篇
  1973年   3375篇
  1972年   3037篇
  1971年   2788篇
排序方式: 共有10000条查询结果,搜索用时 20 毫秒
991.
Results are presented from the synthesis of nanopowders of yttrium-aluminum garnet by the Pechini method. It is established that the Pechini method is a promising technology for producing optically transparent ceramics.  相似文献   
992.
Results of studies focused on the creation of efficient ceramic filters for multi-stage treatment of industrial and household wastes based on natural alumosilicate and technogenic starting materials are presented. The influence of the individual components of the charge on the basic structurally sensitive properties of ceramic materials is established. Compositions of compounds for the fabrication of the carriage of filters with tubular configuration are considered.  相似文献   
993.
In this work various samples of horseradish peroxidase immobilized over organic and inorganic supports were synthesized and studied in 2,3,6-trimethylphenol biocatalitic oxidation. Silica, alumina and commercial samples of polymers MN-100, Sepabeads EC-HA were used as the carriers for horseradish peroxidase. Different methods of immobilization including treatment with chitosan, glutaric dialdehyde and carbodiimide were used to enhance catalytic activity. For synthesized catalysts optimal conditions for 2,3,6-trimethylphenol (main intermediates in vitamin E synthesis) oxidation providing high degree of conversion (more than 95%) and high selectivity to target products (more then 98%) were found. Physicochemical investigations (FTIR spectroscopy, XPS, nitrogen physosorption) of optimal biocatalytic systems were provided.  相似文献   
994.
Combustion of metallothermic mixtures FeO-Cr2O3-Al-C in air at normal conditions was studied upon variation in the size of carbon (graphite) particles and carbon localization in a green sample. Carburization conditions were optimized in terms of graphite particle size.  相似文献   
995.
Conditions for the granulation and heat treatment of coking byproducts—heavy coal tar, acid tars, and distillation residues—are developed so as to produce suitable additives for coking batch. It proves possible to improve poorly clinkering batch by adding a mixture of coal and acidic tar from the sulfate department.  相似文献   
996.
Research on extraction and absorption by ethylene carbonate in chemical technology is reviewed.  相似文献   
997.
Methods of determining coke quality are compared.  相似文献   
998.
Papers regarding Russia’s coke furnaces—in particular, their construction and reconstruction and issues of preservation and operational stability—presented at the Seventeenth Annual Seminar of Coke-Industry Specialists are summarized. The seminar was hosted by OOO EvrazKoksSibir’, a subdivision of OAO ZSMK.  相似文献   
999.
A software package has been developed for planning skull formation dynamics on an oxygen converter lining surface in the faculty of high-temperature materials chemical technology (HMCT) of SPbGTI (TU). An information base is provided making it possible making it possible to use to the software package developed under converter production conditions.  相似文献   
1000.
Powder precursors have been prepared by means of the sol-gel technique and codeposition, and nanoceramics in the ZrO2-Al2O3-rare-earth (RE) oxide system (RE = Ce, Sc, or Y) based on them have been obtained. Physicochemical properties of the resulting ceramic composites have been investigated. The energy model for oxygen-ionic transport processes in a solid solution based on ZrO2, which relies on computer simulation procedure, has been proposed, and the structural, strength, and electrophysical characteristics of the solid solution have been calculated. The obtained materials are promising as high-melting electrochemical sensors in molten oxides.  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