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   9557篇
  免费   12篇
  国内免费   26篇
电工技术   111篇
综合类   37篇
化学工业   138篇
金属工艺   93篇
机械仪表   19篇
建筑科学   16篇
矿业工程   18篇
能源动力   21篇
轻工业   62篇
水利工程   46篇
石油天然气   138篇
武器工业   1篇
无线电   55篇
一般工业技术   107篇
冶金工业   8683篇
原子能技术   6篇
自动化技术   44篇
  2023年   3篇
  2020年   6篇
  2019年   4篇
  2018年   4篇
  2017年   3篇
  2016年   3篇
  2015年   3篇
  2014年   10篇
  2013年   14篇
  2012年   19篇
  2011年   66篇
  2010年   36篇
  2009年   21篇
  2008年   28篇
  2007年   22篇
  2006年   30篇
  2005年   37篇
  2004年   130篇
  2003年   104篇
  2002年   121篇
  2001年   99篇
  2000年   85篇
  1999年   361篇
  1998年   2727篇
  1997年   1518篇
  1996年   965篇
  1995年   556篇
  1994年   424篇
  1993年   560篇
  1992年   109篇
  1991年   113篇
  1990年   115篇
  1989年   106篇
  1988年   106篇
  1987年   91篇
  1986年   98篇
  1985年   66篇
  1983年   13篇
  1982年   37篇
  1981年   39篇
  1980年   79篇
  1979年   5篇
  1978年   13篇
  1977年   183篇
  1976年   434篇
  1975年   9篇
  1969年   2篇
  1963年   2篇
  1955年   7篇
  1954年   1篇
排序方式: 共有9595条查询结果,搜索用时 93 毫秒
11.
12.
13.
14.
黄志文  郗旭林 《山西冶金》2003,26(2):41-42,56
使用液力偶合器因故障频繁,对高炉稳产、高产造成严重威胁,而且维修费用较高,对偶合器改造后,应用金属迭片挠性联轴器其故障率、维修费用都很低。  相似文献   
15.
介绍了长钢烧结厂在24m^2烧结机上采用富氧点火自动控制的实现与应用。  相似文献   
16.
Human immunodeficiency virus (HIV) infection of the thymus could have profound effects on development of the immune response, particularly in children. We and others have established that in addition to infecting and depleting CD4-bearing thymocytes, functional HIV proviruses are found in thymocytes lacking surface CD4 expression. Using in vitro thymocyte cultures, we show that neither HIV-mediated down regulation of CD4 nor CD4-independent infection contributes to the localization of HIV in cells lacking the primary virus receptor. Rather, infection of a CD4-positive precursor cell (CD4 positive/CD8 positive) with subsequent differentiation into a mature CD4-negative phenotype results in productively infected CD4-negative cells. This novel mechanism may contribute to pathogenesis by distributing viral sequences into functional subsets of T cells typically refractory to HIV infection and could account for the presence of viral DNA in CD8-positive lymphocytes recently observed in patients.  相似文献   
17.
Here we are presenting the case of a 70-years-old woman who has hepatic cirrhosis anti-HCV and insulin-dependent diabetes mellitus, without relevant epidemiologic ascendants or previous transfusions and HBV, HIV negatives. On admission to our hospital she showed signs of autoimmune hemolytic anaemia (AHA) which was confirmed by positive direct Coombs test and an improvement in blood test after corticoid treatment. Having discarded other possible causes such as drugs infectious diseases or essential mixed cryoglobulinemia (CME), we put forward the possible association between AHA and infection by HCV, where AHA was an extrahepatic immunological manifestation of HCV. This fact has never been brought to light in previous medical literature.  相似文献   
18.
轧钢生产使用实炉底连续式加热炉加热钢坯,炉内双纵滑管用耐热耐高温材料,无水冷,起到节约水、电的作用,达到节能增效的目的。  相似文献   
19.
Replacement of the pyridinium ring of 6,11-ethanobenzo[b]quinolizinium cations with thiazolium (4a and 4b) and N-methylimidazolium (4c and 4d) resulted in equipotent compounds in the [3H]TCP binding assay. The corresponding N-methyl-1,2,4-triazolium analogs were less potent in this assay. The thiazolium derivative 4b, with a Ki = 2.9 nM, is being evaluated as a possible neuroprotective N-methyl-D-aspartic acid (NMDA) antagonist.  相似文献   
20.
Secretory immunoglobulin A (IgA) antibodies (sIgA) directed against cholera toxin (CT) and surface components of Vibrio cholerae are associated with protection against cholera, but the relative importance of specific sIgAs in protection is unknown. A monoclonal IgA directed against the V. cholerae lipopolysaccharide (LPS), secreted into the intestines of neonatal mice bearing hybridoma tumors, was previously shown to provide protection against a lethal oral dose of 10(7) V. cholerae cells. We show here that a single oral dose of 5 to 50 micrograms of the monoclonal anti-LPS IgA, given within 2 h before V. cholerae challenge, protected neonatal mice against challenge. In contrast, an oral dose of 80 micrograms of monoclonal IgA directed against CT B subunit (CTB) failed to protect against V. cholerae challenge. A total of 80 micrograms of monoclonal anti-CTB IgA given orally protected neonatal mice from a lethal (5-micrograms) oral dose of CT. Secretion of the same anti-CTB IgA antibodies into the intestines of mice bearing IgA hybridoma backpack tumors, however, failed to protect against lethal oral doses of either CT (5 micrograms) or V. cholerae (10(7) cells). Furthermore, monoclonal anti-CTB IgA, either delivered orally or secreted onto mucosal surfaces in mice bearing hybridoma tumors, did not significantly enhance protection over that provided by oral anti-LPS IgA alone. These results demonstrate that anti-LPS sIgA is much more effective than anti-CT IgA in prevention of V. cholerae-induced diarrheal disease.  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