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   837394篇
  免费   53876篇
  国内免费   3798篇
耳鼻咽喉   9828篇
儿科学   26264篇
妇产科学   23524篇
基础医学   123067篇
口腔科学   23607篇
临床医学   71899篇
内科学   166987篇
皮肤病学   23669篇
神经病学   61606篇
特种医学   31664篇
外国民族医学   79篇
外科学   126587篇
综合类   16509篇
现状与发展   2篇
一般理论   211篇
预防医学   61477篇
眼科学   17713篇
药学   61157篇
  3篇
中国医学   2466篇
肿瘤学   46749篇
  2021年   9440篇
  2019年   8692篇
  2018年   9335篇
  2017年   8145篇
  2016年   9237篇
  2015年   10171篇
  2014年   13356篇
  2013年   19702篇
  2012年   21808篇
  2011年   23162篇
  2010年   15469篇
  2009年   15646篇
  2008年   21553篇
  2007年   22828篇
  2006年   24123篇
  2005年   22408篇
  2004年   21870篇
  2003年   21298篇
  2002年   20539篇
  2001年   39158篇
  2000年   39207篇
  1999年   33098篇
  1998年   10800篇
  1997年   9467篇
  1996年   9830篇
  1995年   10042篇
  1994年   9292篇
  1993年   8436篇
  1992年   26115篇
  1991年   25979篇
  1990年   24995篇
  1989年   24913篇
  1988年   22491篇
  1987年   22002篇
  1986年   21000篇
  1985年   19926篇
  1984年   15149篇
  1983年   13002篇
  1982年   7972篇
  1981年   7389篇
  1979年   13226篇
  1978年   9827篇
  1977年   8514篇
  1976年   7940篇
  1975年   8659篇
  1974年   9572篇
  1973年   9116篇
  1972年   8480篇
  1971年   7863篇
  1970年   7546篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
1.
2.
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   
3.
Pharmaceutical Chemistry Journal - An HPLC-MS method for simultaneous quantitative determination of a novel gestagenic pharmaceutical and two of its metabolites in rat and rabbit blood sera was...  相似文献   
4.
5.
We report two British cases of liver abscess, due to Klebsiella pneumoniae and associated with synchronous infection elsewhere, which required liver resection for definitive treatment. They illustrate the geographic spread of aggressive K pneumoniae liver infection and demonstrate the importance of early aggressive treatment.  相似文献   
6.
7.
8.
Sinus venosus atrial septal defect (SV‐ASD) usually coexists with partial anomalous pulmonary vein connection (PAPVC). It is a difficult diagnosis in transthoracic echocardiography (TTE) due to eccentric position of defects. We present a rare case of atypical anatomical variation in PAPVC, which was never described before. Two right pulmonary veins drained into superior vena cava, which overrode SV‐ASD and interatrial septum, a third pulmonary vein into the right atrium. Complete diagnosis could not be set after TTE, nor transesophageal echocardiography, whereas angio‐CT was finally conclusive. This diagnostic approach allowed the surgical planning.  相似文献   
9.
10.
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