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   2223篇
  免费   7篇
化学工业   24篇
金属工艺   1篇
建筑科学   2篇
能源动力   3篇
轻工业   8篇
水利工程   1篇
石油天然气   1篇
无线电   18篇
一般工业技术   10篇
冶金工业   2145篇
自动化技术   17篇
  2024年   1篇
  2023年   1篇
  2022年   4篇
  2021年   3篇
  2020年   1篇
  2019年   5篇
  2018年   8篇
  2017年   5篇
  2016年   5篇
  2015年   2篇
  2014年   6篇
  2013年   6篇
  2012年   3篇
  2011年   1篇
  2008年   1篇
  2007年   1篇
  2006年   2篇
  2004年   3篇
  2003年   3篇
  2000年   1篇
  1999年   72篇
  1998年   626篇
  1997年   364篇
  1996年   266篇
  1995年   154篇
  1994年   117篇
  1993年   126篇
  1992年   21篇
  1991年   34篇
  1990年   26篇
  1989年   39篇
  1988年   43篇
  1987年   39篇
  1986年   25篇
  1985年   35篇
  1984年   1篇
  1983年   3篇
  1982年   10篇
  1981年   15篇
  1980年   14篇
  1978年   3篇
  1977年   40篇
  1976年   88篇
  1975年   2篇
  1973年   1篇
  1971年   1篇
  1970年   1篇
  1966年   1篇
  1955年   1篇
排序方式: 共有2230条查询结果,搜索用时 15 毫秒
31.
32.
33.
We have compared light chain immunohistochemistry in reactive lymphoid tissue and a series of paraffin-embedded B-cell lymphomas using standard trypsin digestion with a heat mediated epitope retrieval method. Fifty-seven B-cell lymphomas (18 high grade, 29 low grade and 10 cases of nodular lymphocyte predominance Hodgkin's disease), two reactive lymph nodes and eight tonsils fixed for known times between 12 h and 2 years were studied. Paraffin-embedded tissue was stained with polyclonal anti-kappa and anti-lambda antibodies. For each antibody staining was performed on two sections, one treated with trypsin digestion and one with microwave heating. Sections were scored from 0 to + + + with 0 representing poor staining and + + + excellent staining. A score of ++ was considered satisfactory. Light chain restriction was recorded if present. Satisfactory staining was obtained in 34/59 cases using trypsin digestion and 56/59 cases using heat retrieval. Light chain restriction was demonstrated in 32/57 (56%) B-cell lymphomas using trypsin digestion and 52/57 (91%) using heat retrieval. Satisfactory staining was obtained in tonsils fixed for up to 48 h using trypsin digestion and up to 2 years using heat retrieval. We have shown that for light chain immunostaining a heat mediated epitope retrieval method produces more consistent and satisfactory results and is effective over a greater range of fixation times than traditional trypsin digestion.  相似文献   
34.
Polypropylene mesh, the routinely used material for mesh laparostomies is expensive. A economical and easily available substitute-nylon net was compared with polypropylene mesh with regard to efficacy and wound complications in a retrospective study. 51 patients, 25 in the polypropylene mesh group and 26 in the nylon net group were studied. The groups were matched with respect to age, sex, indication for surgery and mortality. The mean hospital stay (65 vs 54 days), fate of the wound, incidence of mesh extrusion (26% vs 20%), bowel perforation (1 vs none) and incisional hernia formation (21% vs 20%) in those with polypropylene mesh and nylon net respectively was similar. In conclusion, nylon net is an effective and inexpensive indigenous substitute for polypropylene mesh for mesh laparostomies.  相似文献   
35.
36.
37.
38.
39.
40.
This review reports the different genetic factors that have been identified either as risk factor for Alzheimer's disease (AD) or directly causing the disease. First are reviewed epidemiological data and biological mechanisms about the apoplipoprotein E gene allele epsilon 4 that is a major risk factor for Alzheimer's disease. The second part describes the mutations responsible for early-onset autosomal dominant AD found in three different genes. The gene located on chromosome 21 encodes the amyloid precusor protein (APP). The presenilin 1 and presenilin 2 genes, located on chromosome 14 and 1 respectively, encode not yet known membrane proteins.  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