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   4667篇
  免费   55篇
  国内免费   10篇
耳鼻咽喉   7篇
儿科学   55篇
妇产科学   113篇
基础医学   908篇
口腔科学   106篇
临床医学   389篇
内科学   585篇
皮肤病学   41篇
神经病学   325篇
特种医学   271篇
外科学   338篇
综合类   18篇
预防医学   291篇
眼科学   59篇
药学   854篇
中国医学   68篇
肿瘤学   304篇
  2024年   1篇
  2023年   190篇
  2022年   238篇
  2021年   183篇
  2020年   214篇
  2019年   157篇
  2018年   102篇
  2017年   188篇
  2016年   217篇
  2015年   283篇
  2014年   458篇
  2013年   210篇
  2012年   142篇
  2011年   84篇
  2010年   274篇
  2009年   279篇
  2008年   87篇
  2007年   115篇
  2006年   82篇
  2005年   69篇
  2004年   52篇
  2003年   96篇
  2002年   65篇
  2001年   72篇
  2000年   27篇
  1999年   74篇
  1998年   88篇
  1997年   81篇
  1996年   83篇
  1995年   88篇
  1994年   45篇
  1993年   46篇
  1992年   17篇
  1991年   34篇
  1990年   33篇
  1989年   25篇
  1988年   58篇
  1987年   36篇
  1986年   38篇
  1985年   7篇
  1984年   15篇
  1983年   13篇
  1982年   16篇
  1981年   19篇
  1980年   14篇
  1979年   4篇
  1978年   4篇
  1977年   5篇
  1976年   4篇
排序方式: 共有4732条查询结果,搜索用时 15 毫秒
61.
62.
63.
Background and aimsInflammatory bowel disease (IBD) patients may be at increased risk of acquiring antibiotic-resistant organisms (ARO). We sought to determine the prevalence of colonization of methicillin-resistant Staphylococcus aureus (MRSA), Enterobacteriaceae containing extended spectrum beta-lactamases (ESBL), and vancomycin-resistant enterococi (VRE) among ambulatory IBD patients.MethodsWe recruited consecutive IBD patients from clinics (n = 306) and 3 groups of non-IBD controls from our colon cancer screening program (n = 67), the family medicine clinic (n = 190); and the emergency department (n = 428) from the same medical center in Toronto. We obtained nasal and rectal swabs for MRSA, ESBL, and VRE and ascertained risk factors for colonization.ResultsCompared to non-IBD controls, IBD patients had similar prevalence of colonization with MRSA (1.5% vs. 1.6%), VRE (0% vs. 0%), and ESBL (9.0 vs. 11.1%). Antibiotic use in the prior 3 months was a risk factor for MRSA (OR, 3.07; 95% CI: 1.10–8.54), particularly metronidazole. Moreover, gastric acid suppression was associated with increased risk of MRSA colonization (adjusted OR, 7.12; 95% CI: 1.07–47.4). Predictive risk factors for ESBL included hospitalization in the past 12 months (OR, 2.04, 95% CI: 1.05–3.95); treatment with antibiotics it the past 3 months (OR, 2.66; 95% CI: 1.37–5.18), particularly prior treatment with vancomycin or cephalosporins.ConclusionsAmbulatory IBD patients have similar prevalence of MRSA, ESBL and VRE compared to non-IBD controls. This finding suggests that the increased MRSA and VRE prevalence observed in hospitalized IBD patients is acquired in-hospital rather than in the outpatient setting.  相似文献   
64.
Abstract

The paw paw tree, Asimina triloba. (L.) Dunal (Annonaceae), contains more than 50 bioactive components, primarily annonaceous acetogenins. Some therapeutic activities have been associated with this material, but the potential to mediate a cancer chemopreventive effect has not been reported. In this study, a standardized extract from the twigs, in which bullatacin, asimicin, and trilobacin represent the most potent and major bioactive acetogenins, was tested in the N.-methyl-N.-nitrosourea–induced mammary carcinogenesis model. With Sprague-Dawley rats given a diet containing paw paw extract (1250 and 2500 mg/kg diet; based on maximum tolerated dose studies), mammary tumor latency was increased from 55 to 66 days. However, mammary tumor incidence and multiplicity were not affected by extract consumption.  相似文献   
65.
66.
Cardiovascular calcification is currently viewed as an active disease process similar to embryonic bone formation. Cardiovascular calcification mainly affects the aortic valve and arteries and is associated with increased mortality risk. Aortic valve and arterial calcification share similar risk factors, including age, gender, diabetes, chronic renal disease, and smoking. However, the exact cellular and molecular mechanism of cardiovascular calcification is unknown. Late-stage cardiovascular calcification can be visualized with conventional imaging modalities such as echocardiography and computed tomography. However, these modalities are limited in their ability to detect the development of early calcification and the progression of calcification until advanced tissue mineralization is apparent. Due to the subsequent late diagnosis of cardiovascular calcification, treatment is usually comprised of invasive interventions such as surgery. The need to understand the process of calcification is therefore warranted and requires new imaging modalities which are able to visualize early cardiovascular calcification. This review focuses on the use of new imaging techniques to visualize novel concepts of cardiovascular calcification.  相似文献   
67.
68.
Liver tumours in children are rare and their prognosis are poor. Through a cross and retrospective study, we examined the epidemiological, clinical and therapeutic aspects on a number of patients in our hospital to try and improve the management of cases. This study involved 66 children admitted to the pediatric oncology unit of University Hospital of Treichville in Abidjan between 1991 and 2007. The average age of children was 7.2 years and the sex ratio of 1.4. 42 children lived in the countryside and 52 children were from disadvantaged areas. 63.2% of children were not vaccinated against hepatitis B. The abdominal mass was the primary sign of discovery and these tumours were dominated in both their primitive and secondary forms by the Burkitt's lymphoma.  相似文献   
69.
70.
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