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   4397篇
  免费   379篇
  国内免费   24篇
耳鼻咽喉   38篇
儿科学   106篇
妇产科学   103篇
基础医学   427篇
口腔科学   87篇
临床医学   561篇
内科学   942篇
皮肤病学   46篇
神经病学   527篇
特种医学   160篇
外科学   564篇
综合类   133篇
一般理论   6篇
预防医学   440篇
眼科学   46篇
药学   320篇
中国医学   2篇
肿瘤学   292篇
  2021年   81篇
  2020年   49篇
  2019年   73篇
  2018年   86篇
  2017年   59篇
  2016年   75篇
  2015年   79篇
  2014年   108篇
  2013年   173篇
  2012年   196篇
  2011年   221篇
  2010年   171篇
  2009年   142篇
  2008年   207篇
  2007年   227篇
  2006年   188篇
  2005年   170篇
  2004年   172篇
  2003年   188篇
  2002年   127篇
  2001年   116篇
  2000年   133篇
  1999年   122篇
  1998年   64篇
  1997年   66篇
  1996年   49篇
  1995年   43篇
  1994年   42篇
  1993年   33篇
  1992年   85篇
  1991年   81篇
  1990年   61篇
  1989年   70篇
  1988年   69篇
  1987年   54篇
  1986年   58篇
  1985年   72篇
  1984年   69篇
  1983年   57篇
  1982年   55篇
  1981年   32篇
  1980年   37篇
  1979年   56篇
  1978年   52篇
  1977年   55篇
  1976年   44篇
  1975年   32篇
  1974年   36篇
  1973年   37篇
  1968年   28篇
排序方式: 共有4800条查询结果,搜索用时 15 毫秒
1.
2.
3.
BACKGROUND: On December 26, 2004, the biggest earthquake for 40 years, measuring 9.0 on the Richter scale, triggered a tsunami that pounded the coastal areas of South Asia and East Africa. The effects of the tsunami on skin conditions have not been evaluated. OBJECTIVE: To determine the influence of the tsunami on skin conditions by evaluating the skin problems of patients presenting at hospitals after the tsunami. METHODS: Between 5 and 25 January 2005, two dermatologists evaluated patients who complained of skin problems at an outpatient clinic and emergency room of a general hospital in Banda Aceh, Aceh Province, Indonesia. RESULTS: The total number of patients that presented during the study period was 235 (131 males and 104 females), and they had a total of 265 skin problems. In terms of age distribution, most subjects were in their fourth decade (23.0%), followed by the third (22.6%) and fifth decade (16.6%). The most prevalent skin problems were infections-infestations (32.5%), followed by eczemas (29.8%) and traumatic skin disorders (29.4%). In males, traumatic skin disorders were most common. The great majority of infection-infestation cases involved superficial fungal infections. Contact dermatitis accounted for three-quarters of eczema cases, and mainly involved the arms (40.0%) and legs (27.1%). The majority of traumatic skin disorders were lacerations, punctures and penetrations, and the feet (44.7%) and hands (18.8%) were most frequently affected. CONCLUSIONS: Unhygienic conditions, exposure to a hazardous environment and contact with various objects during and after the tsunami probably increased the prevalence of infections-infestations, traumatic skin disorders and contact dermatitis. To prevent these problems and associated secondary bacterial infections, health-related education and early medical management are required.  相似文献   
4.
Site-directed mutagenesis of the vaccinia virus gene encoding a type I DNA topoisomerase implicates Tyr-274 as the active-site residue that forms a covalent adduct with DNA during cycles of DNA-strand breakage and reunion. Replacement of Tyr-274 by phenylalanine results in loss of the ability of the enzyme to relax negatively supercoiled DNA as well as to form the covalent DNA-protein intermediate. Substitution of phenylalanine for tyrosine at nine other sites in the protein has no apparent effect on enzyme activity. Amino acid sequence alignment reveals Tyr-274 to be homologous to Tyr-727 and Tyr-771, respectively, of the type I topoisomerases from Saccharomyces cerevisiae and Saccharomyces pombe; Tyr-727 and Tyr-771 have been shown to represent the active-site tyrosines of those enzymes. Sequence comparison of the active-site regions defines a motif Ser-Lys-Xaa-Xaa-Tyr common to the viral and cellular type I topoisomerases, including the human enzyme.  相似文献   
5.
Coexistent primary hyperparathyroidism and monoclonal gammopathy, although rare, has been reported previously by a number of investigators. We report four patients with such an occurrence who were seen between 1976 and 1988. Another patient with primary hyperparathyroidism also had multiple myeloma and was in remission for 12 years. These patients represent approximately 1% of the 386 patients with primary hyperparathyroidism seen during the same 12-year period. Although several mechanisms have been proposed to explain this concurrence, we believe it is the result of a chance occurrence. A review of the literature, an estimate of the chance occurrence of coincidental monoclonal gammopathy, benign or malignant, in patients with primary hyperparathyroidism, and some practical implications of this interesting coexistence are presented.  相似文献   
6.
7.
8.
9.
10.
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