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   1648772篇
  免费   111306篇
  国内免费   2596篇
耳鼻咽喉   22757篇
儿科学   53735篇
妇产科学   43372篇
基础医学   243512篇
口腔科学   46270篇
临床医学   148271篇
内科学   310241篇
皮肤病学   37574篇
神经病学   121987篇
特种医学   63435篇
外国民族医学   277篇
外科学   247489篇
综合类   33998篇
现状与发展   3篇
一般理论   407篇
预防医学   118174篇
眼科学   38684篇
药学   129772篇
  10篇
中国医学   4733篇
肿瘤学   97973篇
  2019年   12404篇
  2018年   17812篇
  2017年   13941篇
  2016年   15703篇
  2015年   17450篇
  2014年   23834篇
  2013年   35262篇
  2012年   47754篇
  2011年   50414篇
  2010年   29633篇
  2009年   27842篇
  2008年   46555篇
  2007年   49904篇
  2006年   50732篇
  2005年   47856篇
  2004年   46217篇
  2003年   44229篇
  2002年   42797篇
  2001年   86558篇
  2000年   88432篇
  1999年   73514篇
  1998年   18801篇
  1997年   16347篇
  1996年   16557篇
  1995年   15653篇
  1994年   14201篇
  1993年   13379篇
  1992年   55369篇
  1991年   54094篇
  1990年   53031篇
  1989年   51436篇
  1988年   46543篇
  1987年   45288篇
  1986年   42890篇
  1985年   40237篇
  1984年   29387篇
  1983年   24861篇
  1982年   13769篇
  1979年   26578篇
  1978年   18255篇
  1977年   15965篇
  1976年   14409篇
  1975年   16293篇
  1974年   18985篇
  1973年   18304篇
  1972年   17394篇
  1971年   16291篇
  1970年   15245篇
  1969年   14455篇
  1968年   12999篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
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   
4.
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   
5.
6.
7.
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   
8.
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