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   1122篇
  免费   54篇
  国内免费   56篇
耳鼻咽喉   1篇
儿科学   68篇
妇产科学   8篇
基础医学   125篇
口腔科学   21篇
临床医学   143篇
内科学   263篇
皮肤病学   51篇
神经病学   31篇
特种医学   298篇
外科学   43篇
综合类   23篇
预防医学   39篇
眼科学   5篇
药学   55篇
中国医学   2篇
肿瘤学   56篇
  2023年   4篇
  2022年   3篇
  2021年   8篇
  2020年   9篇
  2019年   7篇
  2018年   18篇
  2017年   3篇
  2016年   6篇
  2015年   13篇
  2014年   13篇
  2013年   39篇
  2012年   20篇
  2011年   13篇
  2010年   34篇
  2009年   55篇
  2008年   18篇
  2007年   53篇
  2006年   22篇
  2005年   22篇
  2004年   14篇
  2003年   11篇
  2002年   13篇
  2001年   13篇
  2000年   14篇
  1999年   19篇
  1998年   71篇
  1997年   82篇
  1996年   101篇
  1995年   61篇
  1994年   58篇
  1993年   52篇
  1992年   18篇
  1991年   18篇
  1990年   21篇
  1989年   37篇
  1988年   36篇
  1987年   34篇
  1986年   44篇
  1985年   40篇
  1984年   8篇
  1983年   14篇
  1982年   13篇
  1981年   9篇
  1980年   11篇
  1979年   8篇
  1978年   12篇
  1977年   9篇
  1976年   13篇
  1975年   13篇
  1973年   2篇
排序方式: 共有1232条查询结果,搜索用时 15 毫秒
991.
992.
993.
目的:利用巢式逆转录-聚合酶链反应扩增的方法,从肌肉组织中扩增人骨形成蛋白2全长cDNA并构建真核表达载体系统。方法:实验于2003-10/2005-10在苏州大学基因工程教研室和北京大学第三医院骨科实验室完成。提取成人肌肉组织内的总RNA,设计内外两对引物以巢式逆转录-聚合酶链反应扩增方法分两次扩增出人骨形成蛋白2全长1188bp基因,经T-A克隆装入pUCM-T质粒载体内,测序验证后,将克隆质粒以Hind Ⅲ和Xba Ⅰ双酶切后与pcDNA3.0载体相连接,构建真核表达载体系统。结果:利用巢式逆转录-聚合酶链反应扩增方法能从成人肌肉组织内扩增出1188bp的人骨形成蛋白2全长cDNA基因,其测序结果显示与Genebank报道序列完全相符。将扩增序列双酶切后与pcDNA3.0载体相连接,经电泳验证,能构建人骨形成蛋白2全长基因的真核表达系统。结论:巢式逆转录-聚合酶链反应扩增方法能从成人肌肉组织内扩增出人骨形成蛋白2全长cDNA基因,并克隆构建真核表达载体系统,为下一步基因组织工程人工骨实验奠定基础。  相似文献   
994.
995.
996.
Diarrhoea-related morbidity and rotavirus infection in France   总被引:1,自引:0,他引:1  
To assess the importance of diarrhoea in France and, speecifically, rotavirus-related diarrhoea among children, we reviewed data obtained from three complementary sources; (1) general practitioner (GP) sentinel surveillance; (2) hospital discharge data from paediatric hospitals; and (3) laboratory based surveillance. The GP sentinel network is based on 500 physicians who electronically notify new cases of eight illnesses, including diarrhoea, each week. It was estimated that abour 3.3 million patients seek medical attention for diarrhoea from their GP each year, with a winter outbreak associated with an increased rate of isolation of rotavirus. A national system of hospital discharge diagnosis was used to estimate the burden of diarrhoeal morbidity in two paediatric wards in Tours, France. Between 1994 and 1996, 1164 patients under 15 y of age (9.7% of all admissions) were dehydrated and 52% were under 1 y old. Hospital admissions had a seasonal pattern similar to notifications from sentinel GP for children under 5 y old. A centralized laboratory surveillance network representing 17 of the 22 French regions describes a rotavirus outbreak each winter that is concomitant of outbreaks detected by the GP sentinel network and seen in hospitals. Most of the isolates (98%) identified through this surveillance system are among children under 5 y of age. All the data reviewed in this study indicate that the epidemiology of rotavirus diarrhoea in France fits well with what has been reported in other developed countries. □ Diarrhoea, general practice, hospitalization, rotavirus  相似文献   
997.
王鲜平  郑静晨  高进 《医学争鸣》2005,26(21):2015-2016
0 引言近百年重大灾害的研究报道,有10余种常见自然灾害给人类造成了灾难性的损失[1]. 对重大灾害救援的国际化趋势,使医院人员被派往国外执行救援任务的机会增多. 我院自参加中国国际救援队以来,医疗分队多次出国紧急医疗救助行动. 为保证更好地完成任务,避免因疾病减员,我院给医疗队员实行了全程健康保健支持,取得了很好的效果.  相似文献   
998.
999.
The advent of transoral robotic surgery (TORS) has allowed transoral approaches for parapharyngeal space (PPS) tumours to be re‐evaluated. It provides enhanced visualisation and instrument access for appropriate tumours. We describe a specific technique, TORS narrow‐field oropharyngectomy, that is ideal for benign PPS tumours which have been violated by intra‐oral biopsy or incision and drainage. This allows the contaminated, overlying oropharyngeal mucosa to be resected en‐bloc with the PPS tumour, reducing the risk of local recurrence. This technique provides a window into the PPS, improving visualisation of underlying neurovascular structures as well as the tumour. This reduces the risk of tumour spillage and leads to superior vascular access and haemorrhage control. This technique is only applicable to PPS tumours that are appropriate for transoral approaches and is specifically designed for those selected patients that have been placed at risk of seeding or local scarring by intra‐oral procedures prior to definitive resection. We present two such cases: a 38‐year‐old male with a PPS inflammatory cyst and a 66‐year‐old female with a PSS pre‐styloid Schwannoma.  相似文献   
1000.
Vanadium compounds have become important in industrial processes, resulting in workplace exposure potential and are present in ambient air as a result of fossil fuel combustion. A series of acute nose-only inhalation toxicity studies was conducted in both rats and mice in order to obtain comparative data on the acute toxicity potential of compounds used commercially. V2O3, V2O4, and V2O5, which have different oxidation states (+3,?+4,?+5, respectively), were delivered as micronized powders; the highly water-soluble and hygroscopic VOSO4 (+4) could not be micronized and was instead delivered as a liquid aerosol from an aqueous solution. V2O5 was the most acutely toxic micronized powder in both species. Despite its lower overall percentage vanadium content, a liquid aerosol of VOSO4 was more toxic than the V2O5 particles in mice, but not in rats. These data suggest that an interaction of characteristics, i.e., bioavailability, solubility and oxidation state, as well as species sensitivity, likely affect the toxicity potential of vanadium compounds. Based on clinical observations and gross necropsy findings, the lung appeared to be the target organ for all compounds. The level of hazard posed will depend on the specific chemical form of the vanadium. Future work to define the inhalation toxicity potential of vanadium compounds of various oxidation states after repeated exposures will be important in understanding how the physico-chemical and biological characteristics of specific vanadium compounds interact to affect toxicity potential and the potential risks posed to human health.  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