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   1493634篇
  免费   111539篇
  国内免费   2906篇
耳鼻咽喉   20740篇
儿科学   49980篇
妇产科学   39048篇
基础医学   208967篇
口腔科学   37932篇
临床医学   133335篇
内科学   302542篇
皮肤病学   30926篇
神经病学   122446篇
特种医学   60513篇
外国民族医学   673篇
外科学   229855篇
综合类   29411篇
现状与发展   2篇
一般理论   551篇
预防医学   111301篇
眼科学   33081篇
药学   108986篇
  3篇
中国医学   2721篇
肿瘤学   85066篇
  2021年   12712篇
  2019年   13536篇
  2018年   18527篇
  2017年   13942篇
  2016年   15260篇
  2015年   17492篇
  2014年   24610篇
  2013年   36453篇
  2012年   51426篇
  2011年   54234篇
  2010年   31905篇
  2009年   30353篇
  2008年   50993篇
  2007年   54374篇
  2006年   54251篇
  2005年   52993篇
  2004年   51359篇
  2003年   48995篇
  2002年   47803篇
  2001年   65936篇
  2000年   68008篇
  1999年   58389篇
  1998年   17678篇
  1997年   15805篇
  1996年   15997篇
  1995年   15101篇
  1994年   14197篇
  1993年   13209篇
  1992年   45571篇
  1991年   44408篇
  1990年   43030篇
  1989年   40862篇
  1988年   37589篇
  1987年   36844篇
  1986年   34304篇
  1985年   32979篇
  1984年   25056篇
  1983年   21061篇
  1982年   12716篇
  1981年   11604篇
  1979年   21835篇
  1978年   15342篇
  1977年   12977篇
  1976年   12116篇
  1975年   12948篇
  1974年   14989篇
  1973年   14403篇
  1972年   13146篇
  1971年   11914篇
  1970年   11185篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
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   
23.
24.
25.
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   
26.
High blood pressure (BP) is a major determinant of cardiovascular events in obesity. The beta2- and beta3-adrenoceptor polymorphisms are associated with obesity and hypertension. In the present study, we examine the relationships of beta2- and beta3-adrenoceptor polymorphisms with further weight gain-induced BP elevation in obese subjects. Changes in BP, body weight, total body fat-mass, waist-to-hip ratio, plasma norepinephrine (NE) and leptin levels, and beta2(Arg16Gly)- and beta3(Trp64Arg)-adrenoceptor polymorphisms were measured periodically over a 5-year period in 55 entry obese (body mass index [BMI]> or =25.0 kg/m(2)) normotensive (BP<140/90 mmHg) men. BP elevation and weight gain were defined as > or =10% increases from entry levels over 5 years in mean BP or BMI. Obese subjects with weight gain, BP elevation or weight gain-induced BP elevation had higher frequencies of the Gly16 allele of Arg16GIy and Arg64 allele of Trp64Arg. Subjects carrying the Gly16 or Arg64 alleles had significantly greater total fat-mass and waist-to-hip ratio at entry and over a 5-year period compared to the subjects who did not carry these polymorphisms. Subjects carrying the Gly16 allele had similar levels of plasma NE, higher levels of plasma leptin and a lower slope of the regression lines between plasma leptin and NE levels. Those carrying the Arg64 allele had higher plasma NE levels at entry and over a 5-year period compared to the subjects without the Arg64 allele, but plasma leptin levels and slopes were similar. The findings demonstrate that the Arg64 allele of the beta3-adrenoceptor polymorphisms relates to weight gain-induced BP elevation accompanying high plasma NE (heightened sympathetic activity) in obese men. The Gly16 allele of the beta2-adrenoceptor polymorphisms links to weight gain-induced BP elevation associated with leptin resistance. beta2- and beta3-adrenoceptor polymorphisms could predict the future BP elevation and further weight gain-induced BP elevation in originally obese subjects.  相似文献   
27.
28.
29.
30.
Infections due to Penicillium species other than P.marneffei are rare. We identified a boy with X-linked chronic granulomatous disease (X-CGD) with a pulmonary nodule and adjacent rib osteomyelitis caused by Penicillium piceum. The only sign of infection was an elevated sedimentation rate. P. piceum was isolated by fine needle aspirate and from excised infected tissues. Surgical removal and one year of voriconazole treatment were very well tolerated and led to complete recovery. Microbiological, microscopic and molecular studies support the fungal diagnosis. P. piceum should be considered as a relevant pathogen in immunocompromised patients.  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