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   764949篇
  免费   53023篇
  国内免费   1612篇
耳鼻咽喉   9772篇
儿科学   24759篇
妇产科学   19067篇
基础医学   117695篇
口腔科学   21432篇
临床医学   69739篇
内科学   147563篇
皮肤病学   16920篇
神经病学   54053篇
特种医学   27521篇
外国民族医学   78篇
外科学   113488篇
综合类   15780篇
现状与发展   3篇
一般理论   263篇
预防医学   56408篇
眼科学   18051篇
药学   58101篇
  3篇
中国医学   2491篇
肿瘤学   46397篇
  2021年   6495篇
  2019年   6360篇
  2018年   9007篇
  2017年   6886篇
  2016年   7708篇
  2015年   8608篇
  2014年   11912篇
  2013年   18023篇
  2012年   23996篇
  2011年   25312篇
  2010年   14893篇
  2009年   13958篇
  2008年   23680篇
  2007年   25414篇
  2006年   25641篇
  2005年   24298篇
  2004年   23561篇
  2003年   22174篇
  2002年   21623篇
  2001年   36990篇
  2000年   37457篇
  1999年   31042篇
  1998年   8564篇
  1997年   7223篇
  1996年   7424篇
  1995年   7077篇
  1994年   6532篇
  1993年   6007篇
  1992年   23460篇
  1991年   23392篇
  1990年   22694篇
  1989年   22481篇
  1988年   20408篇
  1987年   19760篇
  1986年   18794篇
  1985年   17699篇
  1984年   13110篇
  1983年   11118篇
  1982年   6425篇
  1979年   11801篇
  1978年   8426篇
  1977年   7136篇
  1976年   6844篇
  1975年   7539篇
  1974年   8730篇
  1973年   8343篇
  1972年   7830篇
  1971年   7220篇
  1970年   7008篇
  1969年   6401篇
排序方式: 共有10000条查询结果,搜索用时 0 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.
Haemophilia is a common cause of genetically inherited bleeding disorders. Pseudotumours occur in 1–2 % of persons with severe forms of haemophilia. These are a result of repeated haemorrhage into soft tissues, subperiosteum or a site of bone fracture with inadequate resorption of the extravasated blood. There are a number of therapeutic alternatives for this dangerous condition: surgical removal, percutaneous management, irradiation, embolization etc. In this case report, we describe the natural history, clinical course and successful surgical management of a patient with haemophilia who presented with a massive pseudotumour. We also briefly review the relevant literature on the various therapeutic modalities that have been implemented in the management of this rare complication. Though surgeons may be averse to operate on haemophiliacs, primary surgical management as done in our case may prove to be the definitive treatment option for such patients.  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