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   1496篇
  免费   25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 31 毫秒
11.
Hyperimmune anti-human immunodeficiency virus immunoglobulin (HIVIG) is an intravenous immunoglobulin prepared from HIV-infected asymptomatic donors with a CD4 cell count greater than 400 cells/microl and a high titer of antibody to HIV-1 p24 protein. Twelve persons with AIDS received four doses of HMG (two at 50 mg/kg of body weight and then two at 200 mg/kg) every 28 days. Pharmacokinetics were evaluated by measurement of anti-p24 antibody. HIVIG was well tolerated, and all participants completed the study. Three subjects who were not receiving Pneumocystis carinii pneumonia (PCP) prophylaxis developed PCP. The mean value for HIVIG clearance was 3.02 ml/kg/day at 50 mg/kg and 3.65 ml/kg/day at 200 mg/kg (P = 0.027); the mean trough antibody titers (reciprocal units) were 1,442 and 4,428, respectively. This study indicates that high titers of anti-p24 antibody can be maintained with a monthly administration schedule of HIVIG and that short-term safety is acceptable. Comparisons to evaluate the therapeutic potential of HIVIG are justified.  相似文献   
12.
Earlier studies have established that mutant strains of Azotobacter vinelandii that do not synthesize ferredoxin I (AvFdI) overexpress another protein designated Protein X (Morgan, T. V., Lundell, P. J., and Burgess, B. K. (1988) J. Biol. Chem. 263, 1370-1375). This protein has now been purified using two-dimensional gel electrophoresis as an assay. The purified protein is a monomer with M(r) approximately 29,000 which degrades slowly to a specific M(r) approximately 22,000 form when stored in solution. The native protein is bright yellow and contains noncovalently attached FAD that is reduced by either dithionite or NADPH without formation of a stable semiquinone. Titration with NADP+/NADPH gives an E0' value of approximately -327 mV versus SHE. Because this E0' is so close to that of the NADP+/NADPH couple it is not clear if Protein X is an NADPH oxidase or an NADP+ reductase in vivo. Comparison of the NH2-terminal sequence and other properties of Protein X with those of other proteins, suggests that it is likely to be related to the Escherichia coli ferredoxin NADP+ reductase (the fpr gene product), and affinity chromatography shows that Protein X binds specifically to AvFdI.  相似文献   
13.
14.
A new multibranched octopus-type structure of carbon nanofibers is synthesized from a natural precursor, camphor, by a thermal chemical vapor deposition technique. An alloy of Cu:Ni catalyst is prepared by electrochemically coating nickel on a copper sheet, with nickel sulfate as an electrolyte, and heating that nickel-coated copper sheet to a higher temperature. Deposition of carbon on these substrates leads to the formation of a branched nanostructure in the temperature range of 923 K to 1023 K. The fiber diameter increases from 30 nm to 250 nm with increasing pyrolysis temperature. Detailed morphology and the internal structure of these fibers are studied by scanning and transmission electron microscopy.  相似文献   
15.
16.
A new scheme for minimising handover failure probability in mobile cellular communication systems, by exchanging channels between two mobiles moving in opposite directions across the endeavour area of adjacent cells is presented. The performance evaluation of the new scheme is carried out by computer simulation of a two cell model  相似文献   
17.
18.
19.
20.
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