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   308816篇
  免费   4714篇
  国内免费   928篇
电工技术   5427篇
综合类   390篇
化学工业   49159篇
金属工艺   12525篇
机械仪表   9104篇
建筑科学   7513篇
矿业工程   1943篇
能源动力   7084篇
轻工业   28706篇
水利工程   3342篇
石油天然气   7200篇
武器工业   26篇
无线电   32614篇
一般工业技术   60845篇
冶金工业   56662篇
原子能技术   7664篇
自动化技术   24254篇
  2021年   2578篇
  2019年   2276篇
  2018年   4357篇
  2017年   4207篇
  2016年   4562篇
  2015年   3079篇
  2014年   4940篇
  2013年   13295篇
  2012年   7841篇
  2011年   10250篇
  2010年   8436篇
  2009年   9491篇
  2008年   9885篇
  2007年   9702篇
  2006年   8500篇
  2005年   7835篇
  2004年   7199篇
  2003年   6893篇
  2002年   6941篇
  2001年   6764篇
  2000年   6423篇
  1999年   6572篇
  1998年   16376篇
  1997年   12042篇
  1996年   9252篇
  1995年   6965篇
  1994年   6277篇
  1993年   6125篇
  1992年   4617篇
  1991年   4569篇
  1990年   4402篇
  1989年   4436篇
  1988年   4361篇
  1987年   3716篇
  1986年   3713篇
  1985年   4333篇
  1984年   4117篇
  1983年   3756篇
  1982年   3529篇
  1981年   3714篇
  1980年   3561篇
  1979年   3475篇
  1978年   3548篇
  1977年   4106篇
  1976年   5396篇
  1975年   3229篇
  1974年   3080篇
  1973年   3114篇
  1972年   2689篇
  1971年   2512篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Strength of Materials - The paper addresses the investigation of high-strain rate compressive behavior of Al foams subjected to impact at the intermediate striking velocity ranged from 40 to...  相似文献   
102.
103.
The failure of frontline antibiotics in the clinic is one of the most serious threats to human health and requires a multitude of novel therapeutics and innovative approaches to treatment so as to curtail the growing crisis. In addition to traditional resistance mechanisms resulting in the lack of efficacy of many antibiotics, most chronic and recurring infections are further made tolerant to antibiotic action by the presence of biofilms. Herein, we report an expanded set of 5-benzylidene-4-oxazolidinones that are able to inhibit the formation of Staphylococcus aureus biofilms, disperse preformed biofilms, and, in combination with common antibiotics, are able to significantly reduce the bacterial load in a robust collagen-matrix model of biofilm infection.  相似文献   
104.
105.
Potentiometric sensors with plasticized poly(vinyl chloride) membranes based on β-lactam–tetraalkylammonium ion associates sensitive to penicillin antibiotics are proposed. The physicochemical characteristics (solubility product constants and dissociation constants) of active membrane components and the electrode, transport, and selective properties of the membranes of liquidand solid-contact sensors have been studied. The quantitative characteristics of membrane transport (penetrability, ion flux, and transport rate) have been evaluated. The main charge carriers in the membranes and at the membrane/solution interface have been determined from the membrane transport characteristics. The potentiometric sensors are shown to be applicable to the determination of penicillin antibiotics in biological fluids (blood serum and oral fluid) from patients with urinary tract infection.  相似文献   
106.
107.
Metal Science and Heat Treatment - The effect of solid boronizing at 950°C for 2 and 4 h on the phase composition, microstructure, hardness and abrasive wear of steel AISI 304L is studied...  相似文献   
108.
109.
Among the thermoplastic elastomers that play important roles in the polymer industry due to their superior properties, styrene-based species and polyurethane block copolymers are of great interest. Poly(styrene-ethylene-butadiene-styrene) (SEBS) as a triblock copolymer seems to have the potential to meet many demands in different applications due to various industrial requirements where durability, biocompatibility, breaking elongation, and interfacial adhesion are important. In this study, the SEBS triblock copolymer was functionalized with natural (Satureja hortensis, SH) and synthetic (nanopowder, TiO2) agents to obtain composite nanofibers by electrospinning and electrospraying methods for use in biomedical and water filtration applications. The results were compared with thermoplastic polyurethane (TPU) composite nanofibers, which are commonly used in these fields. Here, functionalized SEBS nanofibers exhibited antibacterial effect while at the same time improving cell viability. In addition, because of successful water filtration by using the SEBS composite nanofibers, the material may have a good potential to be used comparably to TPU for the application.  相似文献   
110.
Siglecs are members of the immunoglobulin gene family containing sialic acid binding N-terminal domains. Among them, Siglec-8 is expressed on various cell types of the immune system such as eosinophils, mast cells and weakly on basophils. Cross-linking of Siglec-8 with monoclonal antibodies triggers apoptosis in eosinophils and inhibits degranulation of mast cells, making Siglec-8 a promising target for the treatment of eosinophil- and mast cell-associated diseases such as asthma. The tetrasaccharide 6’-sulfo-sialyl Lewisx has been identified as a specific Siglec-8 ligand in glycan array screening. Here, we describe an extended study enlightening the pharmacophores of 6’-sulfo-sialyl Lewisx and the successful development of a high-affinity mimetic. Retaining the neuraminic acid core, the introduction of a carbocyclic mimetic of the Gal moiety and a sulfonamide substituent in the 9-position gave a 20-fold improved binding affinity. Finally, the residence time, which usually is the Achilles tendon of carbohydrate/lectin interactions, could be improved.  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