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   8472篇
  免费   1篇
  国内免费   1篇
电工技术   1篇
综合类   5篇
化学工业   35篇
金属工艺   5篇
建筑科学   7篇
能源动力   1篇
轻工业   13篇
水利工程   1篇
石油天然气   3篇
武器工业   1篇
无线电   9篇
一般工业技术   11篇
冶金工业   8366篇
原子能技术   1篇
自动化技术   15篇
  2020年   3篇
  2016年   1篇
  2014年   4篇
  2013年   4篇
  2012年   4篇
  2011年   3篇
  2010年   4篇
  2009年   5篇
  2008年   4篇
  2007年   9篇
  2006年   8篇
  2005年   8篇
  2004年   13篇
  2003年   12篇
  2001年   3篇
  2000年   6篇
  1999年   277篇
  1998年   2676篇
  1997年   1480篇
  1996年   947篇
  1995年   547篇
  1994年   420篇
  1993年   526篇
  1992年   61篇
  1991年   102篇
  1990年   100篇
  1989年   87篇
  1988年   93篇
  1987年   91篇
  1986年   95篇
  1985年   66篇
  1984年   2篇
  1983年   9篇
  1982年   36篇
  1981年   37篇
  1980年   77篇
  1979年   2篇
  1978年   13篇
  1977年   181篇
  1976年   431篇
  1975年   9篇
  1973年   1篇
  1972年   1篇
  1963年   3篇
  1962年   1篇
  1958年   2篇
  1957年   1篇
  1955年   8篇
  1954年   1篇
排序方式: 共有8474条查询结果,搜索用时 15 毫秒
81.
Mantle cell lymphoma (MCL) patients represent a difficult problem, sometimes to establish the diagnosis but mostly because of their refractoriness to standard lymphoma treatments. Which treatments to apply and to whom is not yet defined. In this study, we attempted to analyze the clinical features, to identify the major prognostic factors, and to evaluate the outcome of 121 MCL patients treated in our institution between 1979 and 1997. Clinical data, treatment modalities, and International Prognostic Index (IPI) score were evaluated. Median age was 63 years. Patients usually presented with advanced stage disease (87%), disseminated lymph nodes (57%), bone marrow involvement (79%), but with a good performance status (PS) (81%). Lymphocytosis >4000/microl and/or peripheral blood involvement was present in 36% of cases, and gastrointestinal disease in 18%. The t(11;14)(q13;q32) and/or bcl-1 rearrangement was detected in 47/57 studied cases. Median overall survival (OS) was 3.12 years and a longer survival was significantly associated with younger age (<70 years), good PS (<2), localized disease (stage I-II), fewer than two extra-nodal sites, absence of spleen or peripheral blood involvement, normal serum LDH and beta2-microglobulin levels, and hemoglobin level greater than 12 g/dl. However, the IPI failed to identify patients with longer OS and in a multiparametric analysis, only older age, hemoglobin less than 12 g/dl, poor PS, and blood involvement were associated with a poorer outcome. Treatment modalities had no impact on survival with 75% of patients relapsing or progressing. Our data showed that the poor outcome of MCL patients is mainly related to adverse patient characteristics, a highly disseminated tumor, and some unknown parameters associated with the refractoriness to standard therapy.  相似文献   
82.
83.
84.
A new assay termed the dome disappearance method for classical swine fever virus (CSFV) using FS-L3 cells with serum-free culture medium was developed. The CSFV live vaccine GPE- strain grows well and shows a slight cytopathic effect (CPE) in FS-L3 cells. This CPE results in the disappearance of the unique fluid-filled multicellular domes on a single monolayer of FS-L3 cells. By using this phenomenon, dome disappearance, as a marker of infection, it was possible to determine the titers of CSFV and its neutralizing antibody. The virus titer determined by this method shows a good correlation with that determined by immunochemical and interference methods. Furthermore, the amount of neutralizing antibody measured by this method also correlated with that measured by the Exaltation of Newcastle Disease Virus (END) neutralizing method. The dome disappearance method developed in this experiment is a simple and safe procedure and has the great advantage that bovine serum, which may contain antibody against bovine viral diarrhea virus, is not necessary for the cultivation of FS-L3 cells.  相似文献   
85.
Efficacies of the 5-hydroxytryptamine (serotonin) 5-HT3 receptor (5-HT3R) agonists 2-methyl-5-HT, dopamine, and m-chlorophenylbiguanide on 5-HT3R native to N1E-115 cells and on homopentameric 5-HT3R expressed in Xenopus oocytes were determined relative to that of 5-HT. Efficacies of 2-methyl-5-HT and dopamine on 5-HT3R native to differentiated N1E-115 cells are high (54 and 36%) as compared with their efficacies on homopentameric 5-HT3R-A(L) and 5-HT3R-A(S) receptors expressed in oocytes (4-8%). m-Chlorophenylbiguanide does not distinguish between 5-HT3R in N1E-115 cells and in oocytes. The distinct pharmacological profile of 5-HT3R native to differentiated N1E-115 cells is conserved when poly(A)+ mRNA from these cells is expressed in oocytes. The results indicate that, apart from the known 5-HT3R subunits, N1E-115 cells express additional proteins involved in 5-HT3R function.  相似文献   
86.
87.

Background  

Ambient particulate matter and nanoparticles have been shown to translocate to the brain, and potentially influence the central nervous system. No data are available whether this may lead to functional changes in the brain.  相似文献   
88.
在连铸实验装置上 ,以低熔点Pb Sn Bi合金和硅油分别模拟钢液和保护渣 ,对流动控制结晶器内钢液流动规律进行了实验研究。结果表明 ,流动控制结晶器能够控制弯月面的波动和水口区域的流动状态 ,对改善连铸坯表面及内部质量具有良好的作用。  相似文献   
89.
90.
In vitro studies with particles are a major staple of particle toxicology, generally used to investigate mechanisms and better understand the molecular events underlying cellular effects. However, there is ethical and financial pressure in nanotoxicology, the new sub-specialty of particle toxicology, to avoid using animals. Therefore an increasing amount of studies are being published using in vitro approaches and such studies require careful interpretation. We point out here that 3 different conventional pathogenic particle types, PM10, asbestos and quartz, which cause diverse pathological effects, have been reported to cause very similar oxidative stress effects in cells in culture. We discuss the likely explanation and implications of this apparent paradox, and its relevance for testing in nanotoxicology.  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