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   3021860篇
  免费   217259篇
  国内免费   5090篇
耳鼻咽喉   43756篇
儿科学   89308篇
妇产科学   78742篇
基础医学   423588篇
口腔科学   88286篇
临床医学   271481篇
内科学   586275篇
皮肤病学   61492篇
神经病学   248285篇
特种医学   119400篇
外国民族医学   941篇
外科学   462367篇
综合类   68362篇
现状与发展   2篇
一般理论   1161篇
预防医学   233362篇
眼科学   70771篇
药学   227889篇
  70篇
中国医学   5871篇
肿瘤学   162800篇
  2018年   29945篇
  2017年   23246篇
  2016年   25710篇
  2015年   28981篇
  2014年   41303篇
  2013年   62451篇
  2012年   84403篇
  2011年   88991篇
  2010年   52470篇
  2009年   50248篇
  2008年   85126篇
  2007年   90237篇
  2006年   91581篇
  2005年   89171篇
  2004年   85972篇
  2003年   82843篇
  2002年   81772篇
  2001年   145944篇
  2000年   151174篇
  1999年   127637篇
  1998年   34989篇
  1997年   31583篇
  1996年   31410篇
  1995年   30196篇
  1994年   28350篇
  1993年   26332篇
  1992年   102001篇
  1991年   98411篇
  1990年   95074篇
  1989年   92000篇
  1988年   85039篇
  1987年   83430篇
  1986年   78864篇
  1985年   75417篇
  1984年   56270篇
  1983年   47982篇
  1982年   28022篇
  1981年   24854篇
  1979年   52167篇
  1978年   36273篇
  1977年   30784篇
  1976年   28324篇
  1975年   30256篇
  1974年   37217篇
  1973年   35308篇
  1972年   33213篇
  1971年   30879篇
  1970年   29097篇
  1969年   27229篇
  1968年   24730篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Bifid mandibular canal.   总被引:1,自引:0,他引:1  
PURPOSE: To determine the incidence and characteristics of bifid mandibular canals. METHODS: A retrospective study was performed using panoramic radiographs of 2012 patients subjected to dental treatment in the Dental Clinic of the Valencia University Dental School (Valencia, Spain) between 1996 and 1999. The goal was to investigate the presence of double mandibular canals. RESULTS: The extraoral panoramic radiographs revealed a total of 7 images suggestive of bifid canals. Mandibular computed tomography revealed the existence of this anatomic variant in 2 of 3 patients. An analysis was performed on the incidence of this type of image in extraoral panoramic radiography, its possible interpretations, and the clinical implications of bifid mandibular canals. CONCLUSIONS: In this study, 0.35% of canals were bifid. All cases were in women.  相似文献   
72.
Contour defects resulting in deformity caused by lack of tissue can be improved by conventional surgery using autologous tissue, but there is always a donor site morbidity. Integra has been available since the early 1980's for use in acute burns and more recently in reconstruction. It has been shown histologically to act as a tissue regeneration template. The regenerated dermis is buried under an autologous thin split-skin graft. In this study, the principle of burying Integra (without the silicone layer) has been applied to deep tissue defects in 12 reconstructive cases. Such regenerated tissues survive at least 3 years after burying. Modification to the technique to avoid visible edges are being developed.  相似文献   
73.
74.
75.
Published data devoted to making and characterization of the properties of polymeric wound dressings with proteolytic action are reviewed. These data are indicative of individual dependence of the physicochemical properties, activity, and stability of each particular enzyme on the type of polymer matrix and the method of immobilization. In order to obtain wound dressings, which are active in physiological medium and retain their activity upon sterilization, it is necessary to optimize the composition and characteristics of a polymer matrix and the enzyme included into its structure. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 40, No. 8, pp. 24–28, August, 2006.  相似文献   
76.
77.
78.
79.
We evaluated the acquisition and performance of a high-precision locomotor task in patients with Parkinson's disease (PD) and healthy subjects. All subjects walked on a treadmill and had to step repetitively as low as possible over an obstacle without touching it. During blocks 1 and 2, the subjects had full vision and received additional acoustic warning and feedback signals. During block 3, vision became restricted. Changes in foot clearance and the number of obstacle hits were evaluated. Initially, PD patients performed poorer and improved foot clearance slower. After task repetition, the groups performed similarly. Restricting vision deteriorated performance in both groups. The similar performance of PD patients after task repetition might indicate that adequate training could improve adaptive locomotor behavior in PD patients.  相似文献   
80.
Accurate assessment of the amount and intensity of physical activity in daily life is considered very important due to the close relationship between physical activity level, health, disability and mortality. For this reason, assessment of physical activity in daily life has gained interest in recent years, especially in sedentary populations, such as patients with chronic obstructive pulmonary disease (COPD). The present article aims to compare and discuss the two kinds of instruments more commonly used to quantify the amount of physical activity performed by COPD patients in daily life: subjective methods (questionnaires, diaries) and motion sensors (electronic or mechanical methods). Their characteristics are summarised and evidence of their validity, reliability and sensitivity is discussed, when available. Subjective methods have practical value mainly in providing the patients' view on their performance in activities of daily living and functional status. However, care must be taken when using subjective methods to accurately quantify the amount of daily physical activity performed. More accurate information is likely to be available with motion sensors rather than questionnaires. The selection of which motion sensor to use for quantification of physical activity in daily life should depend mainly on the purpose of its use.  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