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   1499篇
  免费   22篇
  国内免费   5篇
电工技术   19篇
综合类   2篇
化学工业   130篇
金属工艺   13篇
机械仪表   18篇
建筑科学   14篇
矿业工程   2篇
能源动力   16篇
轻工业   47篇
水利工程   9篇
无线电   68篇
一般工业技术   196篇
冶金工业   910篇
原子能技术   9篇
自动化技术   73篇
  2024年   6篇
  2023年   8篇
  2022年   13篇
  2021年   26篇
  2020年   23篇
  2019年   27篇
  2018年   27篇
  2017年   24篇
  2016年   14篇
  2015年   11篇
  2014年   25篇
  2013年   47篇
  2012年   30篇
  2011年   38篇
  2010年   27篇
  2009年   30篇
  2008年   29篇
  2007年   27篇
  2006年   27篇
  2005年   31篇
  2004年   10篇
  2003年   16篇
  2002年   16篇
  2001年   7篇
  2000年   9篇
  1999年   34篇
  1998年   232篇
  1997年   152篇
  1996年   119篇
  1995年   76篇
  1994年   52篇
  1993年   60篇
  1992年   11篇
  1991年   28篇
  1990年   12篇
  1989年   25篇
  1988年   24篇
  1987年   20篇
  1986年   13篇
  1985年   19篇
  1984年   3篇
  1983年   7篇
  1982年   6篇
  1981年   5篇
  1980年   6篇
  1979年   3篇
  1977年   13篇
  1976年   48篇
  1973年   3篇
  1971年   2篇
排序方式: 共有1526条查询结果,搜索用时 0 毫秒
41.
Chloride induced reinforcement corrosion in concrete is a serious durability problem. Different sources of chloride, i.e. chloride introduced at the fresh stage of concrete (i.e. internal chloride) and chloride entered during the hardened state (i.e. external chloride) may affect the performance of concrete in different ways. For the performance evaluation of reinforced concrete in chloride environment (i.e. both internal and external chloride), there is a need for performing different electrochemical tests to obtain various corrosion parameters that will specify the possibility and the magnitude of corrosion in concrete. In the present study, the results of an experimental investigation that includes different corrosion tests namely potential measurement, corrosion rate measurement and potentiodynamic polarization test have been presented and analyzed to evaluate the performance of concrete both in internal chloride and external chloride exposure conditions. In addition an attempt is made to correlate the corrosion parameters obtained from internal and external chloride exposure conditions. From the results it was observed that, dropped half-cell potential value obtained from external chloride exposure mostly lie in the active zone obtained from internal chloride exposure. In addition it was observed that there was significant difference in corrosion current values obtained from both internal and external chloride exposure conditions. Further on the basis of overall ranking obtained from the results of critical parameters from different exposure conditions, the performance of different cement–steel combinations against chloride induced rebar corrosion has been evaluated.  相似文献   
42.
43.
The by-products of zinc refineries are used as the primary mineral resources for the commercial production of indium. The discarded LCDs containing adequate amount of indium is rather worth as its secondary resources compared to the by-products of zinc refineries. Mining and recycling rates of indium, respectively from minerals and waste LCDs are in progress to meet its huge demand. Recycling of the LCDs has been dominating over mining, as presently 480t of indium are produced annually from mining, however, that of 650t annually from recycling. Different aspects of the extractive metallurgy of indium are summarized in this review paper.  相似文献   
44.
45.
46.
47.
Wireless Personal Communications - Femtocell deployment is an important strategy when it comes to improvement of QoS metrics in areas of poor cell coverage like indoors in an LTE environment. This,...  相似文献   
48.
Alpha 1 antitrypsin deficiency (AT) is an autosomal recessive disease associated with chronic liver disease in adults and children and emphysema in adults. The disease is one of the most common inherited disorders of the Caucasian population of North Europe and North America and is the most common genetic reason for pediatric orthotopic liver transplantation (OLTx), although it is a rare indication in adults. The natural history of the disease is unpredictable and the pathogenesis of the liver injury unclear. Thirty-five patients with histologically apparent alpha 1 AT accumulation in the liver (22 adults, 13 children) have been transplanted in this center. Clinical features were correlated with the pretransplant phenotype, serum alpha 1 antitrypsin levels and potential precipitating factors. All children were PiZZ homozygotes, most of whom had presented with neonatal hepatitis. The majority of adult patients were heterozygotes presenting with portal hypertension and liver cirrhosis. Current one-year posttransplant survival figures are 73% for adults and 87.5% for children. Replacement of the cirrhotic liver results in acquisition of the donor phenotype, a rise in serum levels of alpha 1 antitrypsin, and apparent prevention of associated disease.  相似文献   
49.
50.
Actinoplanic acids A and B are macrocyclic polycarboxylic acids that are potent reversible inhibitors of farnesyl-protein transferase. Actinoplanic acids A and B were isolated from Actinoplanes sp. MA 7066 while actinoplanic acid B was isolated from both MA 7066 and Streptomyces sp. MA 7099. Actinoplanic acids A and B are competitive with respect to farnesyl diphosphate and are selective inhibitors of farnesyl-protein transferase because they do not inhibit geranylgeranyl-protein transferase type 1 or squalene synthase. MA 7066 is believed to be a novel species of actinomycetes while MA 7099 is believed to be a novel strain of Streptomyces violaceusniger on the basis of morphological, biochemical and chemotaxonomic characteristics as well as its production of actinoplanic acids.  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