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   5508篇
  免费   215篇
  国内免费   70篇
耳鼻咽喉   50篇
儿科学   91篇
妇产科学   200篇
基础医学   457篇
口腔科学   472篇
临床医学   390篇
内科学   1319篇
皮肤病学   58篇
神经病学   392篇
特种医学   293篇
外科学   1083篇
综合类   22篇
现状与发展   1篇
预防医学   162篇
眼科学   196篇
药学   256篇
中国医学   5篇
肿瘤学   346篇
  2024年   4篇
  2023年   44篇
  2022年   61篇
  2021年   216篇
  2020年   96篇
  2019年   156篇
  2018年   186篇
  2017年   136篇
  2016年   150篇
  2015年   145篇
  2014年   248篇
  2013年   309篇
  2012年   497篇
  2011年   542篇
  2010年   314篇
  2009年   282篇
  2008年   433篇
  2007年   491篇
  2006年   396篇
  2005年   334篇
  2004年   239篇
  2003年   198篇
  2002年   157篇
  2001年   33篇
  2000年   15篇
  1999年   27篇
  1998年   12篇
  1997年   13篇
  1996年   13篇
  1995年   10篇
  1994年   9篇
  1993年   7篇
  1992年   2篇
  1991年   1篇
  1990年   2篇
  1989年   2篇
  1988年   2篇
  1984年   2篇
  1983年   2篇
  1981年   1篇
  1980年   3篇
  1977年   1篇
  1975年   2篇
排序方式: 共有5793条查询结果,搜索用时 453 毫秒
81.
82.
83.
Currants and Sultanas (Vitis vinifera L.) are dried vine products produced in Greece and used broadly in the Mediterranean diet. We aimed to investigate the gastric cancer preventive activity of methanol extracts obtained from currants from three different origins in Greece (Vostizza, Nemea, and Messinia) as well as methanol extracts obtained from Sultanas cultivated in the island of Crete as to inhibition of cell proliferation, induction of apoptosis, and inhibition of inflammation. All extracts from 500 μg dried raisins studied suppressed cell proliferation, significantly those obtained from Sultanas from Crete and currants from Nemea. Flow cytometric analysis of Annexin-V labeled cells indicated that Cretan Sultana, Nemea, and Messinia currants at 500 μg dried product/ml medium significantly induced cell death. All extracts from 500 μg dried raisins statistically decreased protein and mRNA levels of ICAM-1 in TNF-alpha stimulated cells. Measurement of IL-8 protein levels and quantification for IL-8 mRNA showed no significant decrease. These results indicate that the methanol extracts from currants, rich in phenolic compounds, exhibit cancer preventive efficacy by limiting cell proliferation, inducing cell death, and suppressing ICAM-1 levels in AGS cells.  相似文献   
84.
INTRODUCTIONIsolated ectopic varices located in the small bowel are uncommon. Portal hypertension caused by liver cirrhosis is the most common predisposing risk factor.PRESENTATION OF CASEWe present an unusual case of massive gastrointestinal bleeding from idiopathic jejunal varices in a 73-year-old Caucasian male without portal hypertension. Exploratory laparotomy disclosed ectopic varices located in the small intestine. Segmental resection of the jejunum with end to end anastomosis resulted in a complete resolution of the haemorrhage. During a 5 year follow up, the patient is stable with no bleeding recurrence.DISCUSSIONInformation on aetiology, diagnosis and management of jejunal varices is reviewed.CONCLUSIONDiagnosis and management of isolated jejunal varices is challenging. Surgeons as well as acute care physicians have to consider idiopatic form of jejunal varices as a potential cause of gastrointestinal bleeding when gastroduodenoscopy and colonoscopy are negative.  相似文献   
85.
Allergic diseases are common and frequently coexist. Allergen immunotherapy (AIT) is a disease‐modifying treatment for IgE‐mediated allergic disease with effects beyond cessation of AIT that may include important preventive effects. The European Academy of Allergy and Clinical Immunology (EAACI) has developed a clinical practice guideline to provide evidence‐based recommendations for AIT for the prevention of (i) development of allergic comorbidities in those with established allergic diseases, (ii) development of first allergic condition, and (iii) allergic sensitization. This guideline has been developed using the Appraisal of Guidelines for Research & Evaluation (AGREE II) framework, which involved a multidisciplinary expert working group, a systematic review of the underpinning evidence, and external peer‐review of draft recommendations. Our key recommendation is that a 3‐year course of subcutaneous or sublingual AIT can be recommended for children and adolescents with moderate‐to‐severe allergic rhinitis (AR) triggered by grass/birch pollen allergy to prevent asthma for up to 2 years post‐AIT in addition to its sustained effect on AR symptoms and medication. Some trial data even suggest a preventive effect on asthma symptoms and medication more than 2 years post‐AIT. We need more evidence concerning AIT for prevention in individuals with AR triggered by house dust mites or other allergens and for the prevention of allergic sensitization, the first allergic disease, or for the prevention of allergic comorbidities in those with other allergic conditions. Evidence for the preventive potential of AIT as disease‐modifying treatment exists but there is an urgent need for more high‐quality clinical trials.  相似文献   
86.
87.
The identification of left ventricular hypertrophy (LVH) through electrocardiographic voltage criteria has been widely studied in patients. However, their validity in “athlete’s heart” remains quite unknown. The aim of this study was to evaluate the most common electrocardiographic indices indicative of LVH compared to the known echocardiographic ones in athletes. The study group comprised 150 male adult competitive athletes (group A) and 50 sedentary participants (group B). Thirteen accepted electrocardiographic voltage criteria indicative of LVH were calculated and correlated with the common echocardiographic indices of left ventricular mass (LVM). Nine of the 13 ECG voltage criteria were significantly increased in athletes compared to controls. Statistically, the Sokolow–Lyon index, which is the most commonly used voltage index was found to be affected by the body mass index (10.7 %, p < 0.05), the group (7.3 %, p < 0.05) and systolic blood pressure (4.5 %, p < 0.05) in total variance of 16.6 % (p < 0.05). No electrocardiographic voltage criterion was significantly correlated with any echocardiographic index, except for the Cornell index that was correlated with end-diastolic volume index (r = 0.29, p < 0.05) and the Sokolow index (V6) with LVMI (r = 0.26, p < 0.05) in group A. We suggested that ECG voltage indices should not be considered valid when assessing LVH in athletes. Thus, the echocardiographic study is preferable in studying training-induced structural cardiac changes.  相似文献   
88.
89.
90.
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