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   641959篇
  免费   11462篇
  国内免费   2091篇
电工技术   11282篇
综合类   561篇
化学工业   97664篇
金属工艺   23293篇
机械仪表   19708篇
建筑科学   15398篇
矿业工程   2785篇
能源动力   17812篇
轻工业   56909篇
水利工程   6163篇
石油天然气   9677篇
武器工业   27篇
无线电   76395篇
一般工业技术   126121篇
冶金工业   120396篇
原子能技术   11963篇
自动化技术   59358篇
  2022年   3433篇
  2021年   6268篇
  2020年   4832篇
  2019年   5818篇
  2018年   10046篇
  2017年   10012篇
  2016年   10858篇
  2015年   7345篇
  2014年   11524篇
  2013年   32535篇
  2012年   18797篇
  2011年   24865篇
  2010年   19769篇
  2009年   21827篇
  2008年   22686篇
  2007年   22271篇
  2006年   19893篇
  2005年   17737篇
  2004年   16899篇
  2003年   16677篇
  2002年   15625篇
  2001年   15498篇
  2000年   14401篇
  1999年   15303篇
  1998年   39069篇
  1997年   27002篇
  1996年   20497篇
  1995年   15297篇
  1994年   13344篇
  1993年   13324篇
  1992年   9373篇
  1991年   8875篇
  1990年   8735篇
  1989年   8242篇
  1988年   7909篇
  1987年   6732篇
  1986年   6532篇
  1985年   7672篇
  1984年   7027篇
  1983年   6305篇
  1982年   5845篇
  1981年   6011篇
  1980年   5550篇
  1979年   5255篇
  1978年   5092篇
  1977年   5866篇
  1976年   7655篇
  1975年   4394篇
  1974年   4107篇
  1973年   4254篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
81.
ABSTRACT

Bacteriocin is a proteinaceous biomolecule produced by bacteria (both Gram-positive and Gram-negative) that exhibits antimicrobial activity against closely related species, and food-borne pathogens. It has recently gained importance and attracted the attention of several researchers looking to produce it from various substrates and bacterial strains. This ushers in a new era of food preservation where the use of bacteriocin in food products will be an alternative to chemical preservatives, and heat treatment which are understood to cause unwanted side effects, and reduce sensory and nutritional quality. However, this new market depends on the success of novel downstream separation schemes from various types of crude feedstocks which are both effective and economic. This review focuses on the downstream separation of bacteriocin from various sources using both conventional and novel techniques. Finally, recommendations for future interesting areas of research that need to be pursued are highlighted.  相似文献   
82.
Topics in Catalysis - In this work, a simple thermal-catalytic system was used to valorize peanut shells (Arachis hypogaea), the residual biomass from the peanut industry. To accomplish this...  相似文献   
83.
Polymer Bulletin - In this study, we synthesized a new ion-imprinted polymer (IIP) based on introduction of amidoxime groups in acrylonitrile, complexation with Cd2+ ions and polymerization with...  相似文献   
84.
The price of cobalt has increased by some 450% in the past two years, mainly due to increasing demand for lithium–ion batteries. With an official 2017 production of 64 kt, the Democratic Republic of Congo produces more than half of the world’s cobalt. African Copperbelt operations have traditionally focused on copper production; however, it has now become imperative to also consider cobalt recovery from these ores. A plethora of processing routes is possible. Most hydrometallurgical flowsheets recover cobalt from the raffinate of the low-grade copper solvent-extraction circuit. Downstream purification processes include sequential precipitation with a variety of reagents, solvent extraction, and ion exchange. Product choices include hydroxide, carbonate, sulfate, and metal cathode. This study assesses technical and economic advantages and limitations of various approaches to the hydrometallurgical processing of cobalt in an African context.  相似文献   
85.
The bromodomain and extra terminal (BET) family of bromodomain-containing proteins (BCPs) have been the subject of extensive research over the past decade, resulting in a plethora of high-quality chemical probes for their tandem bromodomains. In turn, these chemical probes have helped reveal the profound biological role of the BET bromodomains and their role in disease, ultimately leading to a number of molecules in active clinical development. However, the BET subfamily represents just 8/61 of the known human bromodomains, and attention has now expanded to the biological role of the remaining 53 non-BET bromodomains. Rapid growth of this research area has been accompanied by a greater understanding of the requirements for an effective bromodomain chemical probe and has led to a number of new non-BET bromodomain chemical probes being developed. Advances since December 2015 are discussed, highlighting the strengths/caveats of each molecule, and the value they add toward validating the non-BET bromodomains as tractable therapeutic targets.  相似文献   
86.
Debittered trub (brewing waste) is an important source of protein source (70.26%). Trub and whey protein were used for 5% protein enrichment of ice cream frozen by liquid nitrogen. Three formulations were elaborated: ice cream standard (ICS), ice cream with whey protein (ICW) and ice cream with trub (ICT). Chemical composition, rheological properties, texture, overrun, melting rate, scanning electron microscopy and a sensorial test were performed. Results showed that ICT presented a higher viscosity, obtained on the upward curve up to 6.76 Pa s−1, consistency index (22.96 (Pa s−1)n), hysteresis area (140.40 mPa s−1) and hardness (31113.33 g) but a lower melting rate (0.38 g min−1), overrun (13.92%) and sensorial acceptability than the other formulations. The addition of trub debittered for protein enrichment improved ice cream properties and demonstrated that it could be used as a food ingredient.  相似文献   
87.
Journal of Communications Technology and Electronics - Abstract—The article presents a rigorous numerical solution, using the Wiener–Hopf method, to the problem of plane wave...  相似文献   
88.
Neural Computing and Applications - This study presents the design of a tenth-order multiple feedback Chebyshev low-pass filter (MF-C-LPF). Component selection and gain calculation of filters are...  相似文献   
89.
Wireless Personal Communications - The rapid development of Information and Communication Technology and the growing number of devices connected to the Internet make the Internet of Things (IoT) as...  相似文献   
90.
Photonic Network Communications - Optical packet switching is a prominent technology proposing not only a reduction in the energy consumption by the elimination of numerous...  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