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   38674篇
  免费   1809篇
  国内免费   220篇
电工技术   332篇
综合类   92篇
化学工业   5958篇
金属工艺   1070篇
机械仪表   726篇
建筑科学   1180篇
矿业工程   96篇
能源动力   595篇
轻工业   5543篇
水利工程   376篇
石油天然气   170篇
武器工业   2篇
无线电   1521篇
一般工业技术   4623篇
冶金工业   5779篇
原子能技术   163篇
自动化技术   12477篇
  2024年   67篇
  2023年   282篇
  2022年   282篇
  2021年   721篇
  2020年   665篇
  2019年   688篇
  2018年   1250篇
  2017年   1219篇
  2016年   1275篇
  2015年   976篇
  2014年   1347篇
  2013年   2585篇
  2012年   2554篇
  2011年   4677篇
  2010年   2418篇
  2009年   2105篇
  2008年   1829篇
  2007年   1639篇
  2006年   1142篇
  2005年   1175篇
  2004年   1195篇
  2003年   1220篇
  2002年   803篇
  2001年   650篇
  2000年   513篇
  1999年   397篇
  1998年   2034篇
  1997年   1263篇
  1996年   779篇
  1995年   477篇
  1994年   356篇
  1993年   335篇
  1992年   101篇
  1991年   86篇
  1990年   81篇
  1989年   102篇
  1988年   100篇
  1987年   93篇
  1986年   82篇
  1985年   89篇
  1984年   101篇
  1983年   54篇
  1982年   48篇
  1981年   72篇
  1980年   71篇
  1977年   116篇
  1976年   220篇
  1975年   42篇
  1974年   43篇
  1973年   48篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
BACKGROUND: Continent urinary diversion may be necessary in a range of urological abnormalities. In circumstances where the standard techniques are not possible, alternative innovative techniques may be used. METHODS: In a female patient with bladder exstrophy, a continent diversion was recommended. The appendix was not available, the ureters were not suitable and a continent stoma was fashioned from an isolated segment of colon. RESULTS: The stoma proved to be continent, although it was somewhat stenotic. However, clean intermittent catheterization maintained its patency. CONCLUSIONS: A continent catheterizable stoma may be constructed from a segment of colon. The technique may be considered when other well recognized methods are not feasible.  相似文献   
103.
It is essential to know how the immune system acts in different neurological diseases, some of them non very well known or of unknown etiology at all. It was applied Reiber and Felgenhauer's formula in 56 patients with different diseases. IgA, IgM, IgG and albumin were quantified in sera and cerebrospinal fluid by simple immunodiffusion. It was observed more frequent IgG local synthesis and IgA in this sample.  相似文献   
104.
BACKGROUND: An important agent of food intoxication is Staphylococcus aureus, that is able to produce enterotoxins. AIM: To detect Staphylococcus aureus contamination in cafeteria food handlers of a Chilean University. SUBJECTS AND METHODS: Nose, throat, hands and nail samples from 87 food handlers were obtained for microbiological examination. RESULTS: Fifty seven subjects (65.5%) were carriers of Staphylococcus aureus. Enterotoxigenic Staphylococcus aureus was found in 36 subjects (41%). The most frequently found enterotoxin was type B (18 samples) followed by type D (12 samples). Men bad a higher frequency of contamination than women (83 and 57% of positive samples respectively). CONCLUSIONS: The frequency of Staphylococcus aureus contamination among food handlers is high and should prompt personal and environmental hygienic measures.  相似文献   
105.
106.
107.
Two studies designed to investigate the effect of recombinant human erythropoietin (rHuEPO) treatment of anemia in chronic dialysis patients on hemocompatibility were conducted. Study 1, whose main aim was to establish whether treatment with rHuEPO enhances coagulation activation during dialysis, included 15 patients before rHuEPO therapy at a mean hematocrit (HCT) of 22.3% and then during therapy at a HCT of 29.3%. The plasma concentrations of the thrombin-antithrombin III complex were not higher during rHuEPO therapy than before it when performing hemodialysis with a Cuprophan membrane. No significant difference was demonstrated either in the values of activated clotting times (Hemochron), thrombocyte or white blood cell counts (Coulter S+II), or in plasma C5a concentrations (ELISA) established during dialysis sessions before and during rHuEPO therapy. In Study 2, which focused primarily on the question of whether or not rHuEPO therapy increases thrombocyte activation during hemodialysis, 8 patients on chronic dialysis were examined both before therapy at a mean HCT value of 22.1% and during rHuEPO therapy at a HCT of 31.5%, invariably during dialysis with either a Cuprophan or polyacrylonitrile (AN69HF) membrane. The plasma concentrations of beta-thromboglobulin (ELISA) did not differ between the examinations made during rHuEPO and before rHuEPO therapy; however, statistically significant differences were found between dialysis sessions involving Cuprophan and AN69HF membranes. No significant difference between examination before and during rHuEPO was demonstrated in activated clotting time nor thrombocyte and white blood cell counts in this study either. The authors conclude that rHuEPO therapy does not enhance coagulation activation during hemodialysis, does not have an effect on thrombocyte activation, and does not influence complement activation and changes in white blood cell counts.  相似文献   
108.
109.
110.
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