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   1351937篇
  免费   113268篇
  国内免费   6428篇
耳鼻咽喉   16842篇
儿科学   43362篇
妇产科学   36806篇
基础医学   185377篇
口腔科学   36731篇
临床医学   121802篇
内科学   281507篇
皮肤病学   32250篇
神经病学   111956篇
特种医学   56048篇
外国民族医学   277篇
外科学   212072篇
综合类   31658篇
现状与发展   2篇
一般理论   418篇
预防医学   107396篇
眼科学   28291篇
药学   94713篇
  5篇
中国医学   2269篇
肿瘤学   71851篇
  2018年   13674篇
  2017年   10832篇
  2016年   13050篇
  2015年   14590篇
  2014年   20357篇
  2013年   30249篇
  2012年   37100篇
  2011年   39766篇
  2010年   24862篇
  2009年   24321篇
  2008年   37102篇
  2007年   39468篇
  2006年   40573篇
  2005年   39174篇
  2004年   37383篇
  2003年   36413篇
  2002年   34375篇
  2001年   66453篇
  2000年   68314篇
  1999年   56921篇
  1998年   16850篇
  1997年   15131篇
  1996年   16124篇
  1995年   16334篇
  1994年   15201篇
  1993年   14241篇
  1992年   47377篇
  1991年   45945篇
  1990年   44164篇
  1989年   41975篇
  1988年   38903篇
  1987年   38223篇
  1986年   35985篇
  1985年   34763篇
  1984年   26455篇
  1983年   22172篇
  1982年   13888篇
  1981年   12488篇
  1980年   11759篇
  1979年   23612篇
  1978年   17104篇
  1977年   14422篇
  1976年   13215篇
  1975年   13754篇
  1974年   16131篇
  1973年   15435篇
  1972年   14237篇
  1971年   13072篇
  1970年   11915篇
  1969年   11128篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
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   
62.
There is increasing evidence that the assessment of eosinophilic airway inflammation using induced sputum and measurement of airway hyperresponsiveness provides additional, clinically important information concerning asthma control. The aim of this study was to directly compare the effects of different treatments on these markers in patients with asthma and persistent symptoms, despite the use of low-dose inhaled corticosteroids. A double-blind four-way crossover study was performed, which compared a 1-month treatment with budesonide 400 mug b.i.d., additional formoterol, additional montelukast and placebo in 49 patients with uncontrolled asthma despite budesonide 100 mug b.i.d., with each treatment separated by a 4-week washout period. The change in sputum eosinophil count with formoterol (2.4 to 3.8% change, 0.6-fold reduction, 95% confidence interval (CI) 0.5-0.9) differed significantly from placebo (2.8 to 2.5% change, 1.1-fold reduction, 95% CI 0.7-1.6) and high-dose budesonide (2.7 to 1.6% change, 1.6-fold reduction, 95% CI 1.2-2.2). The effects of montelukast did not differ from placebo. The changes in methacholine airway responsiveness were small and did not differ between treatments. High-dose budesonide had the broadest range of beneficial effects on other outcomes, including symptom scores, morning peak expiratory flow and forced expiratory volume in one second. In conclusion, treatment given in addition to low-dose inhaled corticosteroids results in modest benefits. Formoterol and high-dose budesonide have contrasting effects on eosinophilic airway inflammation.  相似文献   
63.
64.
65.
66.
67.
68.
The aim of the present study was to explore differences in the clinical expression, clinical diagnoses and management of airway diseases in a primary-care setting. Patients aged >or=35 yrs who had ever smoked were enrolled when they presented for any reason to one of eight rural primary-care practices. Respiratory symptom questionnaires and spirometry were administered. In total, 1,034 patients had acceptable and reproducible spirometry, of whom 550 (53%) were males and 484 (47%) were females. Males smoked more than females (41.2 versus 29.2 pack-yrs) respectively, and were more likely to have a pre-bronchodilator forced expiratory volume in one second/forced vital capacity <0.70 at 22.4 versus 11.8%, respectively. However, more females than males reported breathlessness (51.0 versus 42.8%, respectively), a prior diagnosis compatible with airflow obstruction and taking respiratory medications (23.4 versus 14.9%, respectively). In conclusion, the current results suggest that females are more likely than males to report breathlessness and be prescribed respiratory medications independent of differences in the severity of airflow obstruction.  相似文献   
69.
70.
最近提出的关于额叶功能的理论认为前额叶皮质,尤其是其背外侧面在确定适合一项特殊任务的一系列反应中起重要作用,并在选择中使上述反应发生偏差。这些活动事实上是为任何类型的非常规任务而执行,而不考虑内容的差别。本研究旨在通过一项解决“洞察力”问题的测试任务(即火柴杆算术作业),来验证Frith“塑造反应空间”假说的预测效力。从Knoblich等人对健康人不能解决火柴杆问题的解释和Frith关于额叶背外侧皮质作用的理论,作者推导出与直觉相左的预测,即对这些相对复杂的任务,外侧额叶皮质局部损伤的患者可能比1组健康受试者完成得更好。要求35例经CT或MRI扫描证实为单个局部脑损伤的患者(年龄为26—65岁)和23例健康受试者(年龄为34—62岁)完成火柴杆作业。研究结果似乎与理论上的预测相一致,虽然仅有43%的健康受试者能解决最困难的火柴杆问题(“C类”),但是却有82%的额叶外侧损伤患者完成了类似问题(Fisher精确概率检验,P〈0.05)。总之,对Frith和Knoblich等人理论的结合进行了确证。  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