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   1461969篇
  免费   111076篇
  国内免费   2578篇
耳鼻咽喉   20369篇
儿科学   49197篇
妇产科学   38731篇
基础医学   205928篇
口腔科学   37751篇
临床医学   128869篇
内科学   296435篇
皮肤病学   30371篇
神经病学   118349篇
特种医学   57177篇
外国民族医学   673篇
外科学   224521篇
综合类   30059篇
现状与发展   3篇
一般理论   656篇
预防医学   112986篇
眼科学   31807篇
药学   107418篇
  3篇
中国医学   2757篇
肿瘤学   81563篇
  2019年   11956篇
  2018年   16535篇
  2017年   12724篇
  2016年   13790篇
  2015年   15854篇
  2014年   22401篇
  2013年   33891篇
  2012年   47191篇
  2011年   50349篇
  2010年   29879篇
  2009年   28106篇
  2008年   48331篇
  2007年   51707篇
  2006年   51536篇
  2005年   50854篇
  2004年   49693篇
  2003年   47696篇
  2002年   46699篇
  2001年   65664篇
  2000年   67778篇
  1999年   58208篇
  1998年   17590篇
  1997年   15853篇
  1996年   16083篇
  1995年   15158篇
  1994年   14320篇
  1993年   13277篇
  1992年   45636篇
  1991年   44492篇
  1990年   43171篇
  1989年   40989篇
  1988年   37814篇
  1987年   37153篇
  1986年   34540篇
  1985年   33261篇
  1984年   25481篇
  1983年   21602篇
  1982年   13360篇
  1981年   12168篇
  1980年   10939篇
  1979年   22083篇
  1978年   15709篇
  1977年   13386篇
  1976年   12461篇
  1975年   13263篇
  1974年   15255篇
  1973年   14656篇
  1972年   13332篇
  1971年   12058篇
  1970年   11356篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Hypochlorite-promoted transformations of trichothecenes, 3. Deoxynivalenol   总被引:1,自引:0,他引:1  
Treatment of deoxynivalenol [3] in MeOH with hypochlorite bleach containing added NaOH gave rise to a single major product, the 9 alpha, 10 alpha, 12 beta, 13 beta-diepoxy-8,15-hemiketal 4. Thus, the reaction followed a very different course from that observed for verrucarol [2], where rearrangement involving opening of the starting 12,13-epoxide and a haloform-like oxidation took place.  相似文献   
992.
993.
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   
994.
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   
995.
996.
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   
997.
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   
998.
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   
999.
1000.
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   
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