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   2859530篇
  免费   227367篇
  国内免费   5220篇
耳鼻咽喉   41055篇
儿科学   89630篇
妇产科学   74970篇
基础医学   413104篇
口腔科学   81981篇
临床医学   261270篇
内科学   553906篇
皮肤病学   59414篇
神经病学   232892篇
特种医学   112984篇
外国民族医学   946篇
外科学   431843篇
综合类   66905篇
现状与发展   3篇
一般理论   1097篇
预防医学   227516篇
眼科学   67495篇
药学   216051篇
  7篇
中国医学   6174篇
肿瘤学   152874篇
  2018年   29424篇
  2017年   22708篇
  2016年   25122篇
  2015年   28319篇
  2014年   40327篇
  2013年   61318篇
  2012年   82463篇
  2011年   87139篇
  2010年   51321篇
  2009年   48911篇
  2008年   82351篇
  2007年   88032篇
  2006年   89017篇
  2005年   86071篇
  2004年   83167篇
  2003年   80004篇
  2002年   78913篇
  2001年   134741篇
  2000年   139038篇
  1999年   117116篇
  1998年   33209篇
  1997年   29897篇
  1996年   29867篇
  1995年   28741篇
  1994年   26943篇
  1993年   25097篇
  1992年   94267篇
  1991年   91596篇
  1990年   88775篇
  1989年   85837篇
  1988年   79580篇
  1987年   78189篇
  1986年   74132篇
  1985年   70485篇
  1984年   53137篇
  1983年   45179篇
  1982年   26999篇
  1981年   24078篇
  1979年   49688篇
  1978年   34976篇
  1977年   29437篇
  1976年   27861篇
  1975年   29579篇
  1974年   36188篇
  1973年   34321篇
  1972年   32235篇
  1971年   29734篇
  1970年   28120篇
  1969年   26129篇
  1968年   23795篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Secondary tricuspid regurgitation (TR) caused by right ventricular enlargement in the setting of left heart disease/pulmonary hypertension has been well described. In contrast, that associated with right atrial enlargement—atrial functional TR (AF‐TR)—remains largely underappreciated. AF‐TR most often occurs in the setting of lone atrial fibrillation, although it is also seen in its absence (idiopathic AF‐TR). Several recent studies have found that the prevalence, hemodynamic significance, and prognosis of AF‐TR are not inconsequential, suggesting increased physician awareness of this novel clinical entity is warranted. This article discusses the pathogenesis, echocardiographic findings, and treatment of this underappreciated cause of secondary TR.  相似文献   
32.
33.
34.
35.
36.
37.
38.
Academic output is just one aspect of a successful career as a plastic surgeon. However, for those with a strong interest in academia, the academic output of a department will likely be a key factor when deciding how to rank jobs. The aim of this study was to quantify and rank the academic output of plastic surgery units across the UK and Ireland. The Institute for Scientific Information (ISI) Web of Science Bibliometric analysis tool was used to collate cumulative (1950–2016), 10 year (2006–2016) and 3 years (2013–2015) research output data for plastic surgery units in the UK and Ireland. Sixty-six plastic surgery units were identified. Departments were ranked for each time period according to the number of papers produced, number of citations (Nc) and h-index (a measure of the impact of scientific output). The top 3 departments for number of papers in the last 10 years were The Royal Free Hospital, London (226) Broomfield Hospital, Chelmsford (218), and Morriston Hospital and Swansea (188). The top 3 for h-number were The Royal Free Hospital (21) Wythenshawe Hospital, Manchester (18) and Morriston Hospital (17). Academic output varies across plastic surgery units in the UK and Ireland. A number of departments have consistently maintained high academic outputs across the years and will be of interest to surgeons hoping to pursue a career in academia.  相似文献   
39.
40.
The purpose of this investigation was to characterize noise levels in spaces designated as “effective quiet” areas on a U.S. Navy aircraft carrier. Noise dosimetry samples were collected in 15 designated spaces, representing 15 noise measurements, while at-sea during airwing carrier qualifications. Equivalent sound level (Leq) measurements were collected during flight operations (Leq (flt ops)), non-flight operations (Leq (non-flt ops)), and over 24-hr periods (Leq (24-hr)). These data were compared to the 70 dBA American Conference of Governmental Industrial Hygienists (ACGIH®) Threshold Limit Value (TLV®) for “effective quiet” areas intended for temporary threshold shift recovery when personnel live and work in a potentially noise hazardous environment for periods greater than 24?hr. The monitored areas were selected based on personnel occupancy/use during off-duty time periods. Areas were classified by either (1) leisure areas that included mess (eating areas), gyms, lounges, an internet cafe, and the fantail social area or (2) berthing (sleeping) areas. The Leq measurements in decibels “A” weighted (dBA) were compared to determine significant differences between Leq (flt ops), Leq (non-flt ops), and Leq (24-hr) and were compared between leisure area and berthing area. Measured noise levels according to time period ranged as follows: (1) Leq (24-hr): 70.8–105.4 dBA; (2) Leq (flt ops): 70–101.2 dBA; and (3) Leq (non-flt ops): 39.4–104.6 dBA. All area measurements over the 24-hr period and during flight operations and 46.7% of the areas during the non-flight operation time period exceeded the “effective quiet” 70 dBA ACGIH TLV. Mean Leqs were 15 dBA higher during flight operations compared to non-flight operations in “effective quiet” areas (p?=?0.001). The Leqs in leisure areas were significantly higher than berthing areas by approximately 21 dBA during non-flight operation periods (p?=?0.001). Results suggest noise levels in “effective quiet” areas frequented by aircraft carrier personnel during off-duty hours when at-sea may inhibit auditory recovery from occupational noise exposures that occur on-duty.  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