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   2224923篇
  免费   157908篇
  国内免费   4926篇
耳鼻咽喉   32089篇
儿科学   73284篇
妇产科学   60916篇
基础医学   314550篇
口腔科学   60320篇
临床医学   197046篇
内科学   433126篇
皮肤病学   49670篇
神经病学   170991篇
特种医学   88731篇
外国民族医学   865篇
外科学   338578篇
综合类   48866篇
现状与发展   9篇
一般理论   628篇
预防医学   161562篇
眼科学   50165篇
药学   171332篇
  30篇
中国医学   6306篇
肿瘤学   128693篇
  2019年   16918篇
  2018年   24210篇
  2017年   18575篇
  2016年   20499篇
  2015年   23592篇
  2014年   32277篇
  2013年   47682篇
  2012年   65420篇
  2011年   68884篇
  2010年   41258篇
  2009年   38719篇
  2008年   64187篇
  2007年   68449篇
  2006年   69208篇
  2005年   66738篇
  2004年   64533篇
  2003年   62371篇
  2002年   60514篇
  2001年   112761篇
  2000年   116464篇
  1999年   98091篇
  1998年   25739篇
  1997年   23016篇
  1996年   23326篇
  1995年   21960篇
  1994年   20456篇
  1993年   19059篇
  1992年   75692篇
  1991年   73209篇
  1990年   71708篇
  1989年   68625篇
  1988年   62688篇
  1987年   61347篇
  1986年   57378篇
  1985年   54627篇
  1984年   40244篇
  1983年   33856篇
  1982年   19105篇
  1981年   17154篇
  1979年   35903篇
  1978年   24556篇
  1977年   21298篇
  1976年   19242篇
  1975年   21317篇
  1974年   24817篇
  1973年   23887篇
  1972年   22407篇
  1971年   20637篇
  1970年   19298篇
  1969年   18073篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
33.
Although studies have documented underuse of controller medications and overuse of short-acting inhaled ss(2)-agonist among children with persistent asthma in disadvantaged communities, the persistence of oral ss(2)-agonist use in pediatric practice has not been studied since inhaled short-acting ss(2)-agonists became widespread. We describe medications used to treat asthma among children 3 to 5 years of age at 10 Head Start and other subsidized preschool centers in East and Central Harlem, New York City. We interviewed 149 parents/guardians of children who were identified as having probable asthma based on physician's diagnosis, persistent symptoms, hospitalization, and medication use. We classified 86 of the 149 children (58%) as having current persistent asthma. Only 15 of them (17%) were reported to have used controller medications at least 5 days/week in the last 4 weeks-only 2 of whom used inhaled corticosteroids. By contrast, 53 children (62%) used oral ss(2)-agonist in the last 4 weeks, often (72%) in conjunction with nebulized or inhaled short-acting ss(2)-agonist. Use of oral ss(2)-agonist was associated with more severe symptoms. This study documents the continued widespread use of oral ss(2)-agonist for treatment of children in a low-income community with high prevalence of asthma.  相似文献   
34.
35.
36.
37.
AIM: To evaluate whether the introduction of a strict protocol approach based on the systemic evaluation of critically ill pregnant women with complications of abortion affected outcome. SETTING: Indigent South Africans managed in the regional and tertiary hospitals of the Pretoria Academic Complex. METHOD: Since 1997 a standard definition of severe acute maternal morbidity (SAMM) has been used in the Pretoria Academic Complex. All cases of SAMM and maternal deaths were entered on the Maternal Morbidity and Mortality Audit System programme. A comparison of outcome of severely ill women who had complications of abortion was made between 1997-1998 (original protocol) and 2002-2004 (strict protocol). OUTCOME MEASURES: The mortality index and prevalence of organ system failure or dysfunction. RESULTS: In 1997-1998 there were 43 women with SAMM who survived and a further 10 maternal deaths due to complications of abortion, compared with 107 women with SAMM and 7 maternal deaths during 2002-2004. The mortality index declined from 18.9% in 1997-1998 to 6.1% in 2002-2004 (p = 0.02, odds ratio 0.28, 95% confidence limits 0.10 - 0.79). Significantly more women had hypovolaemic shock in 2002-2004 compared with 1997-1998 (54.4% v. 35.8%, p = 0.04), but fewer women had immune system failure including septic shock (18.4% v. 47.2%, p = 0.0002) and metabolic dysfunction (0 v. 5.7%, p = 0.03) and there was a trend to less renal failure (10.5% v. 22.6%, p = 0.06) and cardiac failure (4.4% v. 13.2%, p = 0.08). CONCLUSION: The strict protocol approach based on systemic evaluation in managing critically ill pregnant women with complications of abortion, coupled with an intensive, regular feedback mechanism, has been associated with a reduction in the mortality index.  相似文献   
38.
39.
40.
Medullary thyroid carcinoma (MTC) is a rare form of thyroid cancer representing about 10% of all thyroid malignancies. It occurs mostly as a sporadic tumor or in association with autosomal dominant inherited cancer syndromes--multiple endocrine neoplasia (MEN) types 2A and 2B and familial MTC. Germline mutations in exons 8, 10, 11, 13, 14, 15 and 16 of the RET proto-oncogene are found in most of the familial cases. There are only a few published data reporting multiple germline mutations in the RET proto-oncogene. We have detected double germline mutations in 2 different exons on the same RET allele in two MEN 2 families. In the MEN 2A family, double germline mutation in exons 10 (Cys620Phe) and 13 (Tyr791Phe) was detected. In the MEN 2B family, beside the classical germline mutation in exon 16 (Met918Thr) a second germline mutation in exon 13 (Tyr791Phe) was found. This study revealed that MEN 2 syndromes can also be caused by double germline mutations in the RET proto-oncogene and these families can be added to small worldwide cohort of families with multiple germline mutations.  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