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   3230452篇
  免费   258601篇
  国内免费   9383篇
耳鼻咽喉   45513篇
儿科学   101280篇
妇产科学   86826篇
基础医学   449455篇
口腔科学   92285篇
临床医学   295323篇
内科学   639177篇
皮肤病学   70022篇
神经病学   271821篇
特种医学   129692篇
外国民族医学   1111篇
外科学   492899篇
综合类   77028篇
现状与发展   3篇
一般理论   1303篇
预防医学   263357篇
眼科学   73928篇
药学   235110篇
  9篇
中国医学   5843篇
肿瘤学   166451篇
  2018年   33281篇
  2016年   29554篇
  2015年   33343篇
  2014年   47448篇
  2013年   71894篇
  2012年   93454篇
  2011年   99577篇
  2010年   60106篇
  2009年   57900篇
  2008年   94012篇
  2007年   100138篇
  2006年   101203篇
  2005年   98703篇
  2004年   94705篇
  2003年   91821篇
  2002年   89410篇
  2001年   147636篇
  2000年   152557篇
  1999年   128550篇
  1998年   38935篇
  1997年   35112篇
  1996年   35372篇
  1995年   34841篇
  1994年   32633篇
  1993年   30570篇
  1992年   105014篇
  1991年   101787篇
  1990年   98172篇
  1989年   94068篇
  1988年   87529篇
  1987年   86341篇
  1986年   81711篇
  1985年   78517篇
  1984年   59864篇
  1983年   51028篇
  1982年   31597篇
  1981年   28425篇
  1980年   26737篇
  1979年   55736篇
  1978年   39848篇
  1977年   33584篇
  1976年   31366篇
  1975年   32924篇
  1974年   40121篇
  1973年   38213篇
  1972年   35733篇
  1971年   33099篇
  1970年   30927篇
  1969年   28804篇
  1968年   26497篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
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   
92.
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   
93.
94.
BACKGROUND: The recurrent chronic orofacial swelling caused by orofacial granulomatosis (OFG) can cause significant cosmetic and functional problems but can be prevented if the disease is diagnosed early and promptly treated. Although the enlargement of the lips is described to be the most common presenting complaint, the clinical onset of OFG may be characterized by minor associated mucosal and neurological manifestations, making early diagnosis very difficult or, sometimes, merely presumable. PATIENTS AND METHODS: We retrospectively analyzed the clinical manifestations of 19 patients with OFG, who were examined at our institution between 1998 and 2002, in order to determine their initial manifestations and presenting symptoms. RESULTS: A total of 10 patients showed classical recurrent enlargement of the lips (six lower; four upper) as presenting symptom. In the other nine patients, OFG onset was characterized by transient unilateral facial nerve palsy (two cases), intraoral manifestations (two cases), recurrent swelling of the periorbital area (two cases), of the chin (one case), of the zygomatic area (one case), and of the cheeks (one case). CONCLUSION: Our data underlined that OFG onset could be frequently characterized by widely variable, multiform, and temporary clinical findings. Involvement of atypical sites of the orofacial region and presence of single minor manifestations may occur as presenting symptoms, often preceding the development of traditional clinical findings.  相似文献   
95.
96.
97.
98.
99.
Pre-eclamptic toxaemia (PET) may be associated with both endothelial dysfunction (ED) and sleep-disordered breathing (SDB). It was hypothesised that females with PET would demonstrate both SDB and ED, and that a correlation between these two would suggest a potential causative association. A total of 17 females with PET and 25 matched females with uncomplicated pregnancy were studied. They underwent a nocturnal ambulatory sleep study (using Watch_PAT100) and noninvasive evaluation of endothelial function utilising the reactive hyperaemia test (using Endo_PAT 2000). A higher ratio of post- to pre-occlusion pulse-wave amplitude (endothelial function index (EFI)) indicated better endothelial function. Females with PET had a significantly higher respiratory disturbance index (RDI) and lower EFI than controls (18.4+/-8.4 versus 8.3+/-1.3.h(-1), and 1.5+/-0.1 versus 1.8+/-0.1, respectively). Blood pressure significantly correlated with RDI and with EFI. EFI tended to correlate with RDI. In conclusion, these results suggest that both sleep-disordered breathing and endothelial dysfunction are more likely to occur in females with pre-eclamptic toxaemia than in females with uncomplicated pregnancies. The current authors speculate that respiratory disturbances contribute to the functional abnormality of the blood vessels seen in females with pre-eclamptic toxaemia, although causality cannot be determined based on this study.  相似文献   
100.
The aim of this study was to determine whether patients with sickle cell disease (SCD) in steady state had pulmonary abnormalities seen on high-resolution computed tomography (HRCT) and whether any abnormalities correlated with contemporaneously diagnosed lung function abnormalities. A subsidiary question was whether the results of a noninvasive measure of haemolysis (end-tidal carbon monoxide (ETCO) levels) correlated with pulmonary function abnormalities. Thirty three patients with SCD, median (range) age 36 yrs (17-67 yrs) were examined. The degree of lobar volume loss and ground-glass opacification and prominence of central vessels on HRCT were quantitatively assessed. Pulmonary function was assessed by measurements of lung volumes, spirometry, gas transfer and oxygen saturation. ETCO levels were measured using an end-tidal CO monitor. Forced expiratory volume in one second (FEV1), forced vital capacity and total lung capacity significantly correlated with HRCT findings, particularly lobar volume loss. ETCO levels significantly negatively correlated with FEV1, vital capacity measured using a plethysmograph, specific airway conductance and arterial oxygen saturation measured by pulse oxymetry. In conclusion, the present results suggest that high-resolution computed tomography noninvasive assessment of haemolysis might be useful to identify sickle cell disease patients with respiratory function impairment.  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