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   2345869篇
  免费   175129篇
  国内免费   3316篇
耳鼻咽喉   32041篇
儿科学   75870篇
妇产科学   62683篇
基础医学   348171篇
口腔科学   63617篇
临床医学   211197篇
内科学   456785篇
皮肤病学   51738篇
神经病学   185291篇
特种医学   88088篇
外国民族医学   490篇
外科学   353976篇
综合类   47481篇
现状与发展   12篇
一般理论   851篇
预防医学   182494篇
眼科学   54731篇
药学   175092篇
  10篇
中国医学   4576篇
肿瘤学   129120篇
  2021年   18985篇
  2019年   19549篇
  2018年   27081篇
  2017年   20386篇
  2016年   22779篇
  2015年   25668篇
  2014年   36141篇
  2013年   54011篇
  2012年   74747篇
  2011年   79496篇
  2010年   47123篇
  2009年   44600篇
  2008年   74690篇
  2007年   79559篇
  2006年   80375篇
  2005年   77851篇
  2004年   74440篇
  2003年   71772篇
  2002年   69423篇
  2001年   108757篇
  2000年   111492篇
  1999年   93531篇
  1998年   27008篇
  1997年   23675篇
  1996年   24067篇
  1995年   22721篇
  1994年   20901篇
  1993年   19722篇
  1992年   72019篇
  1991年   70094篇
  1990年   68414篇
  1989年   65681篇
  1988年   60326篇
  1987年   59143篇
  1986年   55232篇
  1985年   53018篇
  1984年   39320篇
  1983年   33401篇
  1982年   19865篇
  1979年   35880篇
  1978年   25656篇
  1977年   21237篇
  1976年   20336篇
  1975年   21822篇
  1974年   26155篇
  1973年   24807篇
  1972年   23205篇
  1971年   22039篇
  1970年   20250篇
  1969年   19318篇
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
941.
Thirty-nine primary surgical cases for correction of congenital aural atresia were reviewed for complications and long-term hearing results. Hearing averages of 25 dB for mild atresia, 40 dB for moderate atresia, and 46 dB for severe atresia were obtained. Serviceable hearing was achieved in 64% of the cases. The two most frequent complications were stenosis and recurrent infections of the cavity and canal skin, with an incidence of 33% and 31%, respectively. Use of split-thickness instead of full-thickness skin graft was associated with fewer complications. The goal of this review is also to share the experience of the senior author in the management of this complex problem.  相似文献   
942.
The decoction of Sclerocarya birroea Hochst. shows hypoglycaemic effects, an increase in plasma IRI in normal rats and an incremented oral-glucose tolerance. The decoction is also active against diet-induced hypercholesterolaemia.  相似文献   
943.
944.
Development of an auxotrophic oral live Shigella flexneri vaccine   总被引:11,自引:0,他引:11  
An oral live attenuated Shigella flexneri vaccine candidate strain was constructed by making it auxotrophic and dependent on aromatic metabolites not available in mammalian tissues. An aroD gene of Escherichia coli K12 strain NK 5131, inactivated by insertion in it of the Tn 10 transposon, was transduced using phage P1 into a virulent S. flexneri serotype Y strain (Sfl 1) isolated from a patient with bacillary dysentery. One of the transductant strains Sfl 114 was found to invade HeLa cells in vitro, to cause plaque formation in HeLa monolayers (i.e. maintain intracellular multiplication in vitro), but to be unable to cause keratoconjunctivitis in guinea-pig eyes. When the strain was fed to Macacca fascicularis monkeys it was well tolerated, excreted for 1-4 days, and found to elicit a local intestinal sIgA and serum IgA, IgM and IgG responses. Monkeys challenged with 100 ID50 dose (1 X 10(11) bacteria) of the virulent parent Sfl 1 strain were completely protected from development of diarrhoea. Coloscopy of the monkeys and the sampling of intestinal biopsies showed that the vaccine protected against the surface epithelial erosions and ulcerations seen in unimmunized monkeys. Killing of invading virulent shigellae apparently took place intracellularly in the mucosa suggesting that cellular immune mechanisms played a role in the elicited host defence. The constructed S. flexneri Sfl 114 strain has the properties of a promising shigella vaccine and will next be the subject of studies with human volunteers.  相似文献   
945.
946.
Incidence of hypertension in the Framingham Study.   总被引:6,自引:1,他引:5       下载免费PDF全文
Incidence and trends in incidence of definite hypertension were analyzed based on 30 years follow-up of 5,209 subjects in the Framingham Heart Study cohort. Based on pooling of 15 two-year periods, hypertension incidence per biennium increased with age in men from 3.3 per cent at ages 30-39 to 6.2 per cent at ages 70-79, and in women from 1.5 per cent at ages 30-39 to 8.6 per cent at ages 70-79. No consistent trend in incidence rates was evident for either sex from the 1950s through the 1970s. The proportion of hypertensive subjects receiving antihypertensive medication has increased since 1954-58 and exceeded 80 per cent for both men and women ages 60-89 years in 1979-81. Incidence data presented in this report may serve as a baseline for assessing the impact of future public health efforts in the primary prevention of hypertension.  相似文献   
947.
948.
949.
The epidemiology of drowning in adulthood: implications for prevention   总被引:2,自引:0,他引:2  
Previous epidemiological studies of drowning in the United States have dealt primarily with children. The epidemiology and prevention of drowning in adulthood may be very different. To test this general hypothesis, we analyzed the 293 drownings occurring among Sacramento County residents 20 years of age and above during 1974 to 1985. Drowning rates were highest for men 20-29 years of age (11.5 per 100,000 population) and blacks (7.5 per 100,000 population). Swimmers, boaters, and motor vehicle occupants were most frequently represented. Alcohol use was involved in 48% of cases overall and 77% of those involving motor vehicle occupants. A history of seizure disorder was another contributing factor. Important differences do exist in drowning epidemiology between children and adults. Our results suggest that preventing drowning will be more problematic among adults than among children. The study was also used to test the sensitivity of two commonly used methods of case ascertainment for cases in Sacramento County. A manual review of coroner's records had a sensitivity of 96%. A computerized review of death certificate data from the state's vital statistics data base had a sensitivity of 79%. The sources and implications of these differences are discussed.  相似文献   
950.
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