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   709018篇
  免费   48968篇
  国内免费   1312篇
耳鼻咽喉   9219篇
儿科学   23566篇
妇产科学   17643篇
基础医学   110703篇
口腔科学   19993篇
临床医学   63919篇
内科学   135010篇
皮肤病学   16233篇
神经病学   49897篇
特种医学   25825篇
外国民族医学   76篇
外科学   104734篇
综合类   14926篇
现状与发展   2篇
一般理论   160篇
预防医学   51529篇
眼科学   16383篇
药学   54096篇
  3篇
中国医学   2367篇
肿瘤学   43014篇
  2021年   5521篇
  2018年   7954篇
  2017年   6174篇
  2016年   6902篇
  2015年   7612篇
  2014年   10378篇
  2013年   15517篇
  2012年   20676篇
  2011年   21665篇
  2010年   12826篇
  2009年   12031篇
  2008年   20157篇
  2007年   21644篇
  2006年   22033篇
  2005年   20583篇
  2004年   20110篇
  2003年   19039篇
  2002年   18540篇
  2001年   36374篇
  2000年   36981篇
  1999年   30449篇
  1998年   7910篇
  1997年   6685篇
  1996年   6994篇
  1995年   6651篇
  1994年   6113篇
  1993年   5601篇
  1992年   23019篇
  1991年   22952篇
  1990年   22340篇
  1989年   22124篇
  1988年   20073篇
  1987年   19464篇
  1986年   18506篇
  1985年   17345篇
  1984年   12735篇
  1983年   10769篇
  1982年   5933篇
  1979年   11537篇
  1978年   8145篇
  1977年   6847篇
  1976年   6601篇
  1975年   7287篇
  1974年   8508篇
  1973年   8150篇
  1972年   7678篇
  1971年   7136篇
  1970年   6892篇
  1969年   6324篇
  1968年   5792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.
Bulletin of Experimental Biology and Medicine - Ammonium, an end-product of catabolism, in low doses can promote adaptation of metabolic pathways in erythrocytes under conditions of extreme...  相似文献   
5.
6.
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   
7.
8.
9.
Pharmaceutical Chemistry Journal - Three extracts were produced from the above-ground part of the meadowsweet Filipendula ulmaria (L.) Maxim. using water, 40% ethanol, and 70% ethanol. Comparative...  相似文献   
10.
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   
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