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   1375966篇
  免费   98500篇
  国内免费   2019篇
耳鼻咽喉   19168篇
儿科学   47653篇
妇产科学   36428篇
基础医学   193721篇
口腔科学   34213篇
临床医学   117266篇
内科学   278236篇
皮肤病学   28526篇
神经病学   110033篇
特种医学   55570篇
外国民族医学   660篇
外科学   213116篇
综合类   27891篇
现状与发展   1篇
一般理论   380篇
预防医学   104311篇
眼科学   29043篇
药学   100102篇
  2篇
中国医学   2447篇
肿瘤学   77718篇
  2018年   23873篇
  2017年   18611篇
  2016年   21274篇
  2015年   12908篇
  2014年   17725篇
  2013年   26798篇
  2012年   39442篇
  2011年   47977篇
  2010年   30600篇
  2009年   27544篇
  2008年   46702篇
  2007年   51635篇
  2006年   40161篇
  2005年   40816篇
  2004年   40399篇
  2003年   40334篇
  2002年   38518篇
  2001年   64313篇
  2000年   67017篇
  1999年   56645篇
  1998年   15351篇
  1997年   14023篇
  1996年   14330篇
  1995年   13622篇
  1994年   12947篇
  1993年   11933篇
  1992年   44673篇
  1991年   43610篇
  1990年   42345篇
  1989年   40224篇
  1988年   36990篇
  1987年   36356篇
  1986年   33712篇
  1985年   32378篇
  1984年   24198篇
  1983年   20328篇
  1982年   11805篇
  1981年   10705篇
  1980年   9617篇
  1979年   21432篇
  1978年   14883篇
  1977年   12550篇
  1976年   11756篇
  1975年   12626篇
  1974年   14689篇
  1973年   14126篇
  1972年   12944篇
  1971年   11729篇
  1970年   11074篇
  1969年   10055篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Major depression with psychotic features, dementia, and focal neurologic abnormalities appeared in a Haitian man without AIDS or other syndromes of immune compromise. Neurologic evaluation, including brain biopsy, was nondiagnostic, but CSF culture revealed human immunodeficiency virus (HIV).  相似文献   
993.
Perceptions of job characteristics and job satisfaction of central-area technicians and drug-administration technicians at The Ohio State University Hospitals were analyzed. A questionnaire was administered to 79 pharmacy drug-administration technicians; 44 central-area technicians; 10 pharmacy residents, who served as objective raters (5 in the central area and 5 in the decentral area); 13 central-area pharmacists; and 17 decentral-area pharmacists. Perceived job characteristics were measured with the Job Characteristics Inventory; job satisfaction was measured by the Minnesota Job Satisfaction Questionnaire. The two groups of technicians differed significantly in their perceptions of task identity, task significance, and dealing with others. Significantly greater autonomy in technicians' jobs was perceived to exist by pharmacists and raters in both areas than by technicians. Significantly greater task identity was perceived by the central-area technicians than by their raters, and significantly greater task importance was perceived by both groups of technicians than by their pharmacists and raters. Friendship opportunities were perceived to exist to a significantly greater degree by decentral pharmacists and raters than by the drug-administration technicians. In the institution studied, both central-area and drug-administration technicians tended to be dissatisfied with their jobs. Central-area technicians' satisfaction was influenced most by the technicians' relationships with their supervisors and the feelings of accomplishment they gained. Drug-administration technicians were most satisfied if they believed they had opportunities to use their abilities. Efforts to increase job satisfaction among pharmacy technicians should focus on increasing feedback and task identity.  相似文献   
994.
995.
Although an uncommon cause of sexual dysfunction, hyperprolactinaemia is almost invariably associated with loss of libido and impotence in men. The finding of hyperprolactinaemia should prompt a systematic search for an underlying cause, particularly prolactin-secreting pituitary adenomas; in this condition, sexual dysfunction may antedate other complications of the pituitary tumour by many years.  相似文献   
996.
Plasma pyridoxal-5'-phosphate and pyridoxal levels increased significantly (p less than 0.05) when single, oral bolus doses of pyridoxine were increased from 10 to 25 and from 25 to 50 mg in nine female volunteers. However, when the dose was increased to 100 mg, plasma pyridoxal-5'-phosphate levels did not differ significantly from those recorded after the 50 mg dose. Within 3 h plasma pyridoxal levels rose with a factor of 3.85 compared with the 50 mg dose but high pyridoxal levels were eliminated from the circulation. Renal clearance of pyridoxal remained a constant, low percentage (less than 2.0%) of each pyridoxine supplement in spite of the observed very high circulating pyridoxal levels. Pyridoxine supplementation is discussed in relation to circulating pyridoxal-5'-phosphate and pyridoxal availability for cellular metabolism.  相似文献   
997.
From 1981 through 1985, the authors studied the changes in monthly nosocomial infection rates at the University of Virginia Hospital in Charlottesville, Virginia using the 95% confidence interval for infection rates as a marker of the efficacy of infection control activities. For a 99-month baseline period, monthly infection rates were calculated and the 95% confidence interval was established. In the 60 study months, each monthly rate was compared with the 95% confidence interval for that particular month. At the end of each study year, the monthly infection rates were incorporated into the existing confidence interval. Of 60 monthly rates during the study period, 30 were below the confidence interval (p less than 0.00001), two were above the confidence interval (p = 0.23), and 28 were within the confidence interval. Since there was no reduction in surveillance activity, patient case-mix index, or laboratory sensitivity for organism recovery, these results suggest that monthly nosocomial infection rates at this hospital have decreased when compared with the baseline period. The use of the 95% confidence interval may provide a measure of the efficacy of infection control activities, suggest temporal intervals requiring more intensive infection surveillance, and provide a method for examining the variability in monthly infection rates.  相似文献   
998.
999.
Radiation-induced meningioma. 3 cases   总被引:1,自引:0,他引:1  
During the same year (1984), we have seen 3 cases of meningiomas following radiation therapy of the brain for previously diagnosed tumors. A causal relationship between irradiation and meningioma has been postulated. Nevertheless, the coincidental occurrence in same patient of two different histological lesions is possible. The neoplasms developed after irradiation are of mesenchymal origin; they are fibrosarcomas, osteogenic sarcomas and meningiomas.  相似文献   
1000.
Mucosa isolated from the proximal third of the small intestine of infant rats had much lower cyclic nucleotide concentrations (expressed both per unit wet weight and per unit DNA content) than those determined in the intestinal wall. The steady-state concentrations of both cyclic AMP and cyclic GMP in jejunum showed dramatic increases during the first 5 d post partum. Another increase in cyclic nucleotide concentrations was observed in the isolated mucosa between d 15 and 21. Starvation for 24 h always resulted in lower intestinal cyclic nucleotide concentrations than those of the fed littermates. This effect was more pronounced in younger animals and more evident for cyclic AMP values. Three-week-old rats fed a high carbohydrate diet for 24-48 h exhibited more pronounced elevations in the concentrations of cyclic nucleotides from the jejunal mucosa than did rats fed a high fat diet.  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