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   2592091篇
  免费   185509篇
  国内免费   7616篇
耳鼻咽喉   34385篇
儿科学   85298篇
妇产科学   71638篇
基础医学   364167篇
口腔科学   69848篇
临床医学   234781篇
内科学   516819篇
皮肤病学   62604篇
神经病学   213951篇
特种医学   99976篇
外国民族医学   736篇
外科学   387072篇
综合类   50431篇
现状与发展   5篇
一般理论   969篇
预防医学   196280篇
眼科学   56713篇
药学   188358篇
  9篇
中国医学   5350篇
肿瘤学   145826篇
  2021年   20072篇
  2019年   20693篇
  2018年   29398篇
  2017年   22668篇
  2016年   26314篇
  2015年   29585篇
  2014年   40552篇
  2013年   60576篇
  2012年   80436篇
  2011年   84701篇
  2010年   51134篇
  2009年   49246篇
  2008年   79244篇
  2007年   84094篇
  2006年   85832篇
  2005年   82021篇
  2004年   78979篇
  2003年   76304篇
  2002年   73570篇
  2001年   128544篇
  2000年   131445篇
  1999年   110594篇
  1998年   31332篇
  1997年   27973篇
  1996年   28270篇
  1995年   27428篇
  1994年   25109篇
  1993年   23459篇
  1992年   85232篇
  1991年   81628篇
  1990年   78865篇
  1989年   76130篇
  1988年   69531篇
  1987年   68070篇
  1986年   63601篇
  1985年   60569篇
  1984年   44992篇
  1983年   37975篇
  1982年   22479篇
  1981年   20001篇
  1979年   38993篇
  1978年   27461篇
  1977年   23279篇
  1976年   21514篇
  1975年   22832篇
  1974年   26812篇
  1973年   25388篇
  1972年   23773篇
  1971年   21973篇
  1970年   20197篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
PURPOSE: In children with locally advanced or recurrent malignant tumours, prognosis can be improved by regional deep hyperthermia (RHT) in combination with platin-based chemotherapy. However, because of the increasing number of patients that achieve long-time remission with this therapy, it is necessary to evaluate long-term sequelae of thermochemotherapy. During the years 1993-2004 one has observed avascular osteonecrosis (AON) of the femoral head after RHT in seven children with pelvic germ cell tumours or rhabdomyosarcomas. METHODS: Although AON may develop in patients with malignancies treated with chemo- or radiotherapy alone, RHT might nevertheless contribute to the occurrence of AON. In order to determine potential risk factors for AON after RHT, this study analysed the relationship of AON to the patient's age, medical history and treatment parameters such as thermal dose equivalent and power output. RESULTS AND CONCLUSIONS: In the present study AON was associated with young age as well as intensity of hyperthermia indicated by high power levels that exceed 20 W per kg body weight and/or application of eight or more heat sessions as well as additional radiotherapy. Based on this observation, it was assumed that an optimized three dimensional thermal field modelling may be helpful to avoid hazardous temperatures in the femoral heads during RHT treatment and to reduce AON of the femoral heads.  相似文献   
73.
74.
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   
75.
76.
77.
78.
79.
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   
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