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   178975篇
  免费   50229篇
  国内免费   3148篇
耳鼻咽喉   3052篇
儿科学   5460篇
妇产科学   2158篇
基础医学   31285篇
口腔科学   6896篇
临床医学   22301篇
内科学   41615篇
皮肤病学   10160篇
神经病学   20044篇
特种医学   7588篇
外国民族医学   7篇
外科学   26626篇
综合类   5864篇
现状与发展   5篇
一般理论   55篇
预防医学   9840篇
眼科学   3928篇
药学   15839篇
  18篇
中国医学   4051篇
肿瘤学   15560篇
  2024年   237篇
  2023年   1207篇
  2022年   3059篇
  2021年   5548篇
  2020年   7201篇
  2019年   13139篇
  2018年   13008篇
  2017年   13601篇
  2016年   14883篇
  2015年   16149篇
  2014年   16882篇
  2013年   17925篇
  2012年   13199篇
  2011年   12837篇
  2010年   13830篇
  2009年   9531篇
  2008年   8212篇
  2007年   6689篇
  2006年   6149篇
  2005年   5581篇
  2004年   4694篇
  2003年   4514篇
  2002年   4098篇
  2001年   3672篇
  2000年   3237篇
  1999年   2300篇
  1998年   956篇
  1997年   808篇
  1996年   656篇
  1995年   552篇
  1994年   492篇
  1993年   363篇
  1992年   772篇
  1991年   680篇
  1990年   670篇
  1989年   614篇
  1988年   568篇
  1987年   510篇
  1986年   418篇
  1985年   365篇
  1984年   281篇
  1983年   229篇
  1982年   145篇
  1981年   150篇
  1980年   123篇
  1979年   221篇
  1978年   156篇
  1977年   108篇
  1975年   112篇
  1974年   118篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
122.
123.
Melatonin, the main hormone produced by the pineal gland, is secreted in a circadian manner (24‐hr period), and its oscillation influences several circadian biological rhythms, such as the regulation of clock genes expression (chronobiotic effect) and the modulation of several endocrine functions in peripheral tissues. Assuming that the circadian synchronization of clock genes can play a role in the regulation of energy metabolism and it is influenced by melatonin, our study was designed to assess possible alterations as a consequence of melatonin absence on the circadian expression of clock genes in the epididymal adipose tissue of male Wistar rats and the possible metabolic repercussions to this tissue. Our data show that pinealectomy indeed has impacts on molecular events: it abolishes the daily pattern of the expression of Clock, Per2, and Cry1 clock genes and Pparγ expression, significantly increases the amplitude of daily expression of Rev‐erbα, and affects the pattern of and impairs adipokine production, leading to a decrease in leptin levels. However, regarding some metabolic aspects of adipocyte functions, such as its ability to synthesize triacylglycerols from glucose along 24 hr, was not compromised by pinealectomy, although the daily profile of the lipogenic enzymes expression (ATP‐citrate lyase, malic enzyme, fatty acid synthase, and glucose‐6‐phosphate dehydrogenase) was abolished in pinealectomized animals.  相似文献   
124.
125.
126.
Capillary malformation–arteriovenous malformation syndrome (CM‐AVM) is an autosomal dominant disorder caused by RASA1 mutations. The prevalence and phenotypic spectrum are unknown. Evaluation of patients with multiple CMs is challenging because associated AVMs can be life threatening. The objective of this study was to describe the clinical characteristics of children presenting with features of CM‐AVM to an academic pediatric dermatology practice. After institutional review board approval was received, a retrospective chart review was performed of patients presenting between 2009 and 2012 with features of CM‐AVM. We report nine cases. Presenting symptoms ranged from extensive vascular stains and cardiac failure to CMs noted incidentally during routine skin examination. All demonstrated multiple CMs, two had Parkes Weber syndrome, and two had multiple infantile hemangiomas. Seven patients had family histories of multiple CMs; three had family histories of large, atypical CMs. Six had personal or family histories of AVMs. Genetic evaluation was recommended for all and was pursued by six families; four RASA1 mutations were identified, including one de novo. Consultations with neurology, cardiology, and orthopedics were recommended. Most patients (89%) have not required treatment to date. CM‐AVM is an underrecognized condition with a wide clinical spectrum that often presents in childhood. Further evaluation may be indicated in patients with multiple CMs. This study is limited by its small and retrospective nature.  相似文献   
127.
Acid-suppressive drugs, including histamine-2 receptor antagonists (H2RAs) and proton pump inhibitors (PPIs), are common medications used for treating upper gastrointestinal tract disorders. However, acid-suppressive drugs have been reported to increase the risk of pneumonia in numerous disease populations. However, the relationship between acid-suppressive drugs and stroke-associated pneumonia (SAP) remains controversial.The purpose of this study was to investigate the association between acid-suppressive drug usage and pneumonia among patients with stroke by using a nationwide data set.A population-based cohort study was conducted using a data set from the Taiwanese National Health Insurance Research Database. Data on patients with new-onset stroke from 2010 to 2011 were collected. Patients with and without acid-suppressive drug usage were followed up to identify the occurrence of any type of pneumonia. We estimated the adjusted hazard ratios (HRs) by using the Cox proportional hazards model.The study cohort comprised 7965 patients with new-onset stroke. The incidence of pneumonia was 6.9% (552/7965) and more than 40% (225/552) of patients developed pneumonia within 3 months after an acute stroke. Acid-suppressive drug usage was an independent risk factor of pneumonia. The adjusted HR for the risk of pneumonia in patients with new-onset stroke using acid-suppressive drugs was 1.44 (95% confidence interval [CI] = 1.18–1.75, P < 0.01). Only PPI usage increased risk of chronic SAP (adjusted HR = 1.46, 95% CI = 1.04–2.05).Acid-suppressive drug usage was associated with a slightly increased risk of SAP. Physicians should exercise caution when prescribing acid-suppressive drugs to patients with stroke, particularly at the chronic stage.  相似文献   
128.
129.
130.
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