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   2169692篇
  免费   153902篇
  国内免费   3199篇
耳鼻咽喉   31321篇
儿科学   72273篇
妇产科学   59006篇
基础医学   307550篇
口腔科学   59335篇
临床医学   190962篇
内科学   422976篇
皮肤病学   48656篇
神经病学   167639篇
特种医学   86494篇
外国民族医学   859篇
外科学   331490篇
综合类   44903篇
现状与发展   2篇
一般理论   617篇
预防医学   158497篇
眼科学   48953篇
药学   166636篇
  9篇
中国医学   4683篇
肿瘤学   123932篇
  2018年   22393篇
  2017年   17191篇
  2016年   19059篇
  2015年   21439篇
  2014年   29604篇
  2013年   44539篇
  2012年   61017篇
  2011年   64593篇
  2010年   38489篇
  2009年   36304篇
  2008年   60952篇
  2007年   65260篇
  2006年   66134篇
  2005年   63937篇
  2004年   61996篇
  2003年   59935篇
  2002年   58404篇
  2001年   111551篇
  2000年   115507篇
  1999年   97241篇
  1998年   25286篇
  1997年   22646篇
  1996年   22993篇
  1995年   21663篇
  1994年   20171篇
  1993年   18865篇
  1992年   75301篇
  1991年   72900篇
  1990年   71417篇
  1989年   68358篇
  1988年   62453篇
  1987年   61095篇
  1986年   57159篇
  1985年   54429篇
  1984年   40100篇
  1983年   33737篇
  1982年   19022篇
  1981年   17073篇
  1979年   35768篇
  1978年   24444篇
  1977年   21235篇
  1976年   19175篇
  1975年   21254篇
  1974年   24748篇
  1973年   23828篇
  1972年   22349篇
  1971年   20586篇
  1970年   19261篇
  1969年   18047篇
  1968年   16196篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
104.
105.
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   
106.
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   
107.
An increase in chronic beryllium disease (CBD) has been suggested due to higher industrial use of beryllium alloys. Since occupational CBD is a perfect phenocopy of sarcoidosis, it might be misdiagnosed as sarcoidosis. In the current it was hypothesised that CBD exists in cohorts of sarcoidosis patients. In a prospective case study, sarcoidosis patients were evaluated for potential beryllium exposure. In those patients in whom beryllium exposure was confirmed and beryllium hypersensitivity demonstrated, the diagnosis of sarcoidosis was rejected and corrected to CBD. In 84 patients seen for re-evaluation or making a diagnosis of sarcoidosis, beryllium exposure was recognised and a diagnosis of CBD was made in 34 out of 84 patients. The time lag between clinical diagnosis of sarcoidosis and the final diagnosis of CBD ranged 0-18 yrs (median 3 yrs) and the mean (range) age at time of diagnosis of CBD was 43.9(25-80) yrs. Beryllium-contaminated workplaces causing disease encompassed a wide spectrum of industries and technical trades in which beryllium-exposure is generally not perceived as a health hazard. In conclusion, chronic beryllium disease still belongs to the spectrum of differential diagnoses of granulomatous disorders.  相似文献   
108.
The aim of the current study was to investigate whether alterations in N-terminal pro brain natriuretic peptide (NT-proBNP) reflect changes in right ventricular structure and function in pulmonary hypertension patients during treatment. The study consisted of 30 pulmonary hypertension patients; 15 newly diagnosed and 15 on long-term treatment. NT-proBNP, right heart catheterisation and cardiac magnetic resonance imaging measurements were performed, at baseline and follow-up. There were no significant differences between newly diagnosed patients and those on treatment at baseline or follow-up with respect to NT-proBNP, haemodynamics and right ventricular parameters. Relative changes in NT-proBNP during treatment were correlated to the relative changes in right ventricular end-diastolic volume index (r = 0.59), right ventricular mass index (r = 0.62) and right ventricular ejection fraction (r = -0.81). N-terminal pro brain natriuretic peptide measurements reflect changes in magnetic resonance imaging-measured right ventricular structure and function in pulmonary hypertension patients. An increase in N-terminal pro brain natriuretic peptide over time reflects right ventricular dilatation concomitant to hypertrophy and deterioration of systolic function.  相似文献   
109.
110.
Rare kidney allograft recipients enjoy unaltered graft function years after interruption of their immunosuppressive treatment. To assess the extent to which this state of 'operational tolerance' (TOL) is specific to the graft and not the result of a global immunodeficiency, we analyzed the response of such patients following influenza vaccination. Hemagglutination inhibition titers and frequency of IFNgamma-secreting T cells were measured before 1 and 3 months after vaccination. The proportion of healthy volunteers (HV) responding to vaccine was significantly higher than that of immunosuppressed (IS) patients. Three 'TOL' patients presented a humoral response similar to that of HV, whereas the two others had a poor response, like the IS recipients. Although the small number of patients does not allow for definitive conclusions to be made, these data suggest that the status of tolerance may be heterogeneous, with some patients with a global immunodeficiency and others with an adapted response to vaccination.  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