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   1370051篇
  免费   26705篇
  国内免费   6798篇
电工技术   33234篇
综合类   6284篇
化学工业   248968篇
金属工艺   62084篇
机械仪表   38141篇
建筑科学   40831篇
矿业工程   11178篇
能源动力   49548篇
轻工业   95912篇
水利工程   13790篇
石油天然气   36227篇
武器工业   128篇
无线电   191793篇
一般工业技术   262551篇
冶金工业   116309篇
原子能技术   33623篇
自动化技术   162953篇
  2021年   14384篇
  2020年   11649篇
  2019年   14412篇
  2018年   13655篇
  2017年   12826篇
  2016年   20109篇
  2015年   17023篇
  2014年   28396篇
  2013年   87233篇
  2012年   32388篇
  2011年   42981篇
  2010年   40015篇
  2009年   49083篇
  2008年   40831篇
  2007年   37469篇
  2006年   42198篇
  2005年   36437篇
  2004年   39150篇
  2003年   38875篇
  2002年   36488篇
  2001年   32514篇
  2000年   30866篇
  1999年   29598篇
  1998年   27293篇
  1997年   27993篇
  1996年   26958篇
  1995年   26710篇
  1994年   25501篇
  1993年   25415篇
  1992年   24744篇
  1991年   21729篇
  1990年   22251篇
  1989年   21178篇
  1988年   19659篇
  1987年   18123篇
  1986年   17490篇
  1985年   20858篇
  1984年   21471篇
  1983年   19434篇
  1982年   18624篇
  1981年   18657篇
  1980年   17265篇
  1979年   17904篇
  1978年   17186篇
  1977年   16277篇
  1976年   16112篇
  1975年   15529篇
  1974年   15103篇
  1973年   15165篇
  1972年   12721篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Ding  M.  Li  C. X.  Liang  Z. M.  Ju  J. S. 《Strength of Materials》2022,54(3):536-544
Strength of Materials - In order to study the failure process of a large-scale spherical bearing, the finite element simulation method was used to establish the full-scale finite element model of...  相似文献   
52.
Majumder  Bhaswar  Venkatesh  T. G. 《Wireless Networks》2022,28(7):2967-2982
Wireless Networks - Mobile data offloading is a current-day networking paradigm to channelize certain fraction of the cellular data traffic over unlicensed spectrum of WiFi. In this paper, we...  相似文献   
53.
Maidebura  Y. E.  Malin  T. V.  Zhuravlev  K. S. 《Semiconductors》2022,56(6):340-345
Semiconductors - The transformation of a two-dimensional GaN layer into three-dimensional islands (2D–3D transition) under increasing temperature in a flow of ammonia is investigated...  相似文献   
54.
Journal of Communications Technology and Electronics - A modified resonator method for determining the complex permittivity of materials based on the theory of small perturbations where a resonator...  相似文献   
55.
Journal of Communications Technology and Electronics - In this paper, we develop suboptimal algorithms for receiving and processing binary offset carrier (BOC) signals for use in global navigation...  相似文献   
56.
Wireless Personal Communications - Since the last decade, cloud-based Electronic Health Records (EHRs) have achieved important consideration to facilitate remote access of patient medical records....  相似文献   
57.
Journal of Computer and Systems Sciences International - The replacement of complex technical system elements is optimized using a genetic algorithm. Its various operators are analyzed and modified...  相似文献   
58.
利用水力空化过程产生局部的高温、高压、高射流以及强大的剪切力等极端化学物理条件改质处理沙特重质原油,试验结果表明:沙特重质原油经过水力空化改质后粘度由13.61降低至7.22mm2/s,残碳由7.16%降低至6.48%,实沸点蒸馏后减压渣油降低1个百分点。进一步采用APPI FT-IR MS、XRD、FT-IR、SEM和粒度分布等技术研究了水力空化改质对沙重原油分子组成,沥青质团聚体微晶结构、沥青质胶束粒径分布、沥青质官能团、沥青质形貌等方面的影响,从分子角度阐述空化改质重油的机理。研究结果表明:水力空化改质后沙重原油分子量分布、芳烃类化合物缔合作用变小;沥青质对低DBE化合物吸附性能降低;沥青质团聚体微晶结构更加松散;沥青质胶束粒度分布降低;沥青质分子相互团聚作用力减弱。进一步考察了水力空化改质前后减压渣油延迟焦化性能,改质处理后焦炭产率降低1.85个百分点,液体收率和气体产率分别增加1.52和0.33个百分点,水力空化改质对沥青质性质、结构特点的改善能够有效的提高其加工性能。  相似文献   
59.
Traditional West African pearl millet couscous products are popular; however, their preparation is laborious, time-consuming and energy-demanding, involving agglomeration, steaming, drying and sieving steps. In this study, a process was developed to produce millet couscous using a high pressure, high temperature and low-cost single-screw extruder. The innovation was to directly process the cooked low-moisture extrudate to a couscous product by drying and milling to the appropriate particle size (ranging between 1 and 2 mm). Throughput for the traditional process as prepared for commercial sale is 50 kg per day, but with the same amount of labour, the extrusion process yields ~350 kg per day. A consumer sensory study held in Niamey (Niger) showed that the extruded millet couscous was comparable to traditional couscous, though this was dependent on selection of the proper millet variety. This novel extrusion process could stimulate small- to medium-scale manufacturing of couscous and couscous-type products in West Africa.  相似文献   
60.
Food- and waterborne viruses, such as human norovirus, hepatitis A virus, hepatitis E virus, rotaviruses, astroviruses, adenoviruses, and enteroviruses, are major contributors to all foodborne illnesses. Their small size, structure, and ability to clump and attach to inanimate surfaces make viruses challenging to reduce or eliminate, especially in the presence of inorganic or organic soils. Besides traditional wet and dry methods of disinfection using chemicals and heat, emerging physical nonthermal decontamination techniques (irradiation, ultraviolet, pulsed light, high hydrostatic pressure, cold atmospheric plasma, and pulsed electric field), novel virucidal surfaces, and bioactive compounds are examined for their potential to inactivate viruses on the surfaces of foods or food contact surfaces (tools, equipment, hands, etc.). Every disinfection technique is discussed based on its efficiency against viruses, specific advantages and disadvantages, and limitations. Structure, genomic organization, and molecular biology of different virus strains are reviewed, as they are key in determining these techniques effectiveness in controlling all or specific foodborne viruses. Selecting suitable viral decontamination techniques requires that their antiviral mechanism of action and ability to reduce virus infectivity must be taken into consideration. Furthermore, details about critical treatments parameters essential to control foodborne viruses in a food production environment are discussed, as they are also determinative in defining best disinfection and hygiene practices preventing viral infection after consuming a food product.  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