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   809篇
  免费   47篇
  国内免费   75篇
儿科学   24篇
妇产科学   9篇
基础医学   72篇
口腔科学   32篇
临床医学   79篇
内科学   155篇
皮肤病学   89篇
神经病学   46篇
特种医学   110篇
外科学   84篇
综合类   83篇
预防医学   12篇
眼科学   5篇
药学   89篇
中国医学   4篇
肿瘤学   38篇
  2022年   9篇
  2021年   10篇
  2020年   7篇
  2019年   21篇
  2018年   17篇
  2017年   22篇
  2016年   13篇
  2015年   14篇
  2014年   14篇
  2013年   31篇
  2012年   30篇
  2011年   32篇
  2010年   33篇
  2009年   32篇
  2008年   27篇
  2007年   76篇
  2006年   42篇
  2005年   28篇
  2004年   38篇
  2003年   29篇
  2002年   25篇
  2001年   14篇
  2000年   26篇
  1999年   14篇
  1998年   30篇
  1997年   25篇
  1996年   31篇
  1995年   22篇
  1994年   11篇
  1993年   21篇
  1992年   9篇
  1991年   13篇
  1990年   12篇
  1989年   18篇
  1988年   10篇
  1987年   17篇
  1986年   10篇
  1985年   17篇
  1984年   5篇
  1983年   8篇
  1982年   9篇
  1981年   10篇
  1980年   9篇
  1979年   3篇
  1978年   3篇
  1977年   6篇
  1976年   5篇
  1975年   6篇
  1964年   3篇
  1957年   3篇
排序方式: 共有931条查询结果,搜索用时 0 毫秒
841.
842.
843.
Background Eruptive pseudo‐angiomatosis (EPA) is a rare, relatively newly described cutaneous disorder characterized by the sudden onset of several bright red, angioma‐like papules surrounded by blanched halo. Its aetiology is unknown; however, viral infection or mosquito bites have been speculated as possible causes. Objective This study aims to determine the clinical and histopathological features of EPA, and whether it is associated with Epstein–Barr virus (EBV) infection. Methods We conducted a retrospective chart review of 25 EPA cases from 2006 to 2008. In order to determine latent EBV infection, EBV‐encoded small RNA (EBER) in situ hybridization was performed in 18 subjects. To determine EPA's distinguishing histological characteristics, we compared the cases with 22 control cases of perivascular lymphocytic infiltration for haematoxylin and eosin, CD3, CD4, CD8, CD31 and c‐kit staining patterns. Results The patient sample's female‐to‐male ratio was 2.1 : 1, and the patients’ age ranged from 5 to 79 years (average 46 years). The lesions appeared during the months of July to September in all but 3 patients. Skin biopsies demonstrated capillary ectasia with perivascular mononuclear cellular infiltrates in the upper dermis. Most patients were otherwise healthy, and routine laboratory results were all normal except in one patient who had diabetes. The skin lesions faded without any treatment in 1–2 weeks. Results of EBER in situ hybridization were all negative. The only histological distinguishing feature of EPA was the presence of intravascular neutrophils, which was found to be present in 19 of the 20 EPA cases (95%), in contrast to only 3 of the 22 control subjects (14%) (P < 0.0001). Conclusion The sudden onset of lesions during the summer months among our patients supports the ‘paraviral eruption’ concept of this probably underdiagnosed condition. The significant presence of intravascular neutrophils may be a diagnostic clue of EPA in South Korea.  相似文献   
844.
845.
Upwards of 1 in 10 adults worldwide may be affected by severe periodontitis, making the disease more prevalent than cardiovascular disease. Despite its global scope, its impact on pain, oral function, and the wellbeing of individuals, and the disproportionate burden of disease and the socioeconomic impact on communities, the perception that periodontal disease is a public health problem remains low. Although there have been substantial improvements in our understanding of the etiology of periodontal disease and how we can prevent and control it, these advances have been primarily focused on individual, patient-focused approaches. The prevention of periodontal disease depends on improving currently available individual interventions and on determining what public health interventions can be effective and sustainable under real-life conditions. Currently, public health approaches for periodontal disease prevention and control are lacking. This review traces the historical strategies for prevention of periodontal disease in an epidemiologic transition context, using a modified model developed for cardiovascular disease, and presents a possible public health approach. Improving periodontal disease prevention and control will need to take into consideration the core activities of a public health approach: assessment, policy development, and assurance.  相似文献   
846.
847.
Murphy  WA; Gutierrez  FR; Levitt  RG; Glazer  HS; Lee  JK 《Radiology》1985,154(1):225-226
We describe a simple method that uses patient positioning to obtain oblique views of the human heart by magnetic resonance (MR) imaging. These views provide MR images that directly correlate with conventional anterior or posterior oblique radiography.  相似文献   
848.
849.
本文以青霉素G扩环而得的7-苯乙酰氨基-3-甲基-3-头孢烯-4-羧酸(Ⅰ)为原料,合成了12个C3位上有1,2,3-三唑甲基取代的新头孢菌素衍生物(Ⅷ1~12),并经分析确证了各化合物的结构。体外抑菌试验结果表明,其中6个化合物,即Ⅶ2~4,9~11,不仅对革兰氏阳性菌有较高的抑制作用。而且对革兰氏阴性菌也有高度敏感性。  相似文献   
850.
We highlight the spectrum of scintigraphic findings likely to be encountered in patients with ectopic gastric mucosa with illustrative cases for each such finding. 11 children (aged 4 months to 120 months, all males) underwent (99)Tc(m)-pertechnetate scintigraphic evaluation for ectopic gastric mucosa. Functioning ectopic gastric mucosa was detected in Meckel's diverticulae in three patients, in small bowel duplications in four, in a gastric duplication in one, and in intrathoracic foregut duplication cysts in three. Ectopic functioning gastric mucosa in Meckel's diverticulum, and gastric duplication is visualized simultaneously with the stomach while in intestinal duplications tracer activity can be visualized in the dynamic sequence and even before gastric tracer visualization. In the three patients with intrathoracic duplication cysts, the functioning ectopic gastric mucosa was evident only in the delayed (99)Tc(m)-pertechnetate images, much later than the visualization of stomach activity. Therefore, acquisition of delayed images are useful when the initial images are equivocal or negative in children with intrathoracic foregut duplication cysts. In addition, we suggest a hypothesis of a possible mechanism for the uptake of pertechnetate in ectopic gastric mucosa in some patients with intrathoracic forget duplication cysts. In conclusion, a variety of scintigraphic patterns may be found in patients with ectopic gastric mucosa undergoing (99)Tc(m)-pertechnetate scintigraphy depending upon the location and size of the ectopic tissue.  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