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   13768篇
  免费   743篇
  国内免费   344篇
耳鼻咽喉   856篇
儿科学   322篇
妇产科学   158篇
基础医学   806篇
口腔科学   301篇
临床医学   1440篇
内科学   1889篇
皮肤病学   161篇
神经病学   714篇
特种医学   662篇
外科学   1436篇
综合类   2378篇
预防医学   738篇
眼科学   73篇
药学   850篇
  7篇
中国医学   356篇
肿瘤学   1708篇
  2024年   12篇
  2023年   134篇
  2022年   363篇
  2021年   507篇
  2020年   458篇
  2019年   334篇
  2018年   385篇
  2017年   426篇
  2016年   455篇
  2015年   462篇
  2014年   954篇
  2013年   839篇
  2012年   820篇
  2011年   951篇
  2010年   767篇
  2009年   791篇
  2008年   761篇
  2007年   759篇
  2006年   620篇
  2005年   506篇
  2004年   452篇
  2003年   363篇
  2002年   306篇
  2001年   313篇
  2000年   233篇
  1999年   212篇
  1998年   187篇
  1997年   164篇
  1996年   159篇
  1995年   151篇
  1994年   124篇
  1993年   109篇
  1992年   75篇
  1991年   74篇
  1990年   82篇
  1989年   60篇
  1988年   61篇
  1987年   46篇
  1986年   35篇
  1985年   56篇
  1984年   38篇
  1983年   19篇
  1982年   37篇
  1981年   43篇
  1980年   36篇
  1979年   29篇
  1978年   16篇
  1977年   12篇
  1976年   15篇
  1972年   28篇
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
11.
BackgroundIdentifying electroencephalogram (EEG) cortical arousals are crucial in scoring hypopneas and respiratory efforts related arousals (RERAs) during a polysomnogram. As children have high arousal threshold, many of the flow limited breaths or hypopneas may not be associated with visual EEG arousals, hence this may lead to potential underestimation of the degree of sleep disordered breathing. Pulse wave amplitude (PWA) is a signal obtained from finger photoplethysmography which correlates directly to finger blood flow. The drop in PWA has been shown to be a sensitive marker for subcortical/autonomic and cortical arousals. Our aim was to use the drop in PWA as a surrogate for arousals to guide scoring of respiratory events in pediatric patients.MethodsTen polysomnograms for patients between the ages of 5–15 years who had obstructive apnea-hypopnea indices between 1 and 5 events/hour were identified. Patients with syndromes were excluded. A drop in PWA signal of at least 30% that lasted for 3 s was needed to identify subcortical/autonomic arousals. Arousals were rescored based on this criteria and subsequently respiratory events were rescored. Paired t-tests were employed to compare PSG indices scored with or without PWA incorporation.ResultsThe sample of 10 children included 2 females, and the average age was 9.8 ± 3.1 years. Overall, polysomnography revealed an average total sleep time of 464.1 ± 25 min, sleep efficiency of 92% +/−4.2, sleep latency of 19.6 ± 17.0 min, rapid eye movement (REM) latency 143 ± 66 min, N1 3.9% +/−2.0, N2 50.3% +/−12.0, N3 28.2% +/−9.1, REM 16.7% +/−4.0, and wakefulness after sleep onset (WASO) 18.1 ± 7.5 min. Including arousals from PWA changes, respiratory indices significantly increased including total AHI (2.3 ± 0.7 vs 5.7 ± 2.1, p < 0.001), obstructive AHI (1.45 ± 0.7 vs 4.8 ± 1.8, p < 0.001), and RDI (2.36 ± 0.7 vs 7.6 ± 2.0, p < 0.001). Likewise, total arousal index was significantly higher (8.7 ± 2.3 vs 29.4 ± 6.5, p < 0.001).ConclusionsThe drop in pulse wave amplitude signal is a useful marker to guide scoring arousals that are not otherwise easily identified in pediatric polysomnography and subsequently helped in scoring respiratory events that otherwise would not be scored. Further studies are needed to delineate if such methodology would affect clinical outcome.  相似文献   
12.
《Cor et vasa》2015,57(3):e157-e162
IntroductionObstructive sleep apnea (OSA) is often connected with arterial hypertension and it could also be a cause of secondary hypertension. Treatment of arterial hypertension and optimal blood pressure level are important for prevention of cardiovascular complications. It is not well known how to treat patients with OSA and arterial hypertension. Also many patients with OSA suffer from metabolic syndrome which worsen their prognosis.AimThe aim of our study was to assess arterial hypertension compensation in patients with metabolic syndrome and moderate to severe OSA and to analyze used pharmacotherapy.Materials and methods85 hypertensive patients (75 men) with metabolic syndrome, average age 53.6 ± 9.3 years, were evaluated using overnight sleep study with diagnosis of OSA, average apnea–hypopnea index (AHI) 56.3 ± 23. Patients underwent 24 h ambulatory blood pressure monitoring (ABPM) and their current pharmacotherapy data were obtained. Appropriate combinations of antihypertensive drugs (patients with metabolic syndrome) were derived from ESH/ESC 2013 guidelines.ResultsArterial hypertension was well compensated in only 11.8% of the patients. 24.7% patients were treated according to current guidelines. Fisher's exact test with analysis of adjusted residues has found higher rate of blood pressure subcompensation in patients treated with triple+ combination of drugs (p = 0.035, 51.4% vs 10%).ConclusionOnly a small number of patients had optimal blood pressure level and were treated according to current ESH/ESC guidelines. We have to constantly appeal to all physicians to perform ABPM in patients with OSA.  相似文献   
13.
14.
15.
16.
17.
18.
ObjectiveProgrammed death ligand 1 (PD-L1) has been reported to be connected to prognosis in individuals with malignant pleural mesothelioma (MPM), although there is no consensus based on data from previous studies. Accordingly, this quantitative meta-analysis investigated prognostic and clinicopathological utility of PD-L1 in patients with MPM.MethodsA comprehensive search of the PubMed, Web of Science, Embase, and Cochrane Library databases for articles published up to October 4, 2019 was performed. Studies using immunohistochemical techniques to detect/quantify the expression of PD-L1 in MPM tissue were enrolled in the analysis. The combined hazard ratio (HR) and corresponding 95% confidence interval (CI) was applied to assess the association between PD-L1 expression and overall survival (OS).ResultsA total of 11 studies comprising 1606 patients was included in the present meta-analysis. For OS, pooled data revealed an HR of 1.50 (95% CI 1.32–1.70; p < 0.001), suggesting that patients with PD-L1 overexpression experience inferior OS. Subgroup analysis revealed that elevated PD-L1 remained a significant prognostic indicator for worse OS, irrespective of sample size, cut-off value, ethnicity, and Newcastle-Ottawa Scale score. Moreover, PD-L1 overexpression was associated with non-epithelioid histology (odds ratio 4.30 [95% CI 1.89–9.74]; p < 0.001).ConclusionsResults of this meta-analysis show that elevated expression of PD-L1 could be a factor predicting poorer survival in patients with MPM.  相似文献   
19.
20.
We prospectively evaluated the effectiveness of contrast-enhanced ultrasonography (CEUS) for differentiation of benign versus malignant portal vein thrombosis (PVT). We studied a total of 43 patients with chronic liver disease, hepatocellular carcinoma-suggestive nodules and confirmed PVT, in whom the nature of the PVT was confirmed by follow-up imaging (US, computed tomography and/or magnetic resonance imaging) performed up to 6 mo after CEUS. PVT was assessed by US, Doppler US and CEUS with respect to vessel wall disruption and/or invasion, color Doppler vascularization, pulsed Doppler vascularization pattern and CEUS enhancement and vascularization pattern, and thrombi were classified as benign or malignant based on these findings. Follow-up studies revealed malignant PVT in 22 of the 43 patients (51%) and benign PVT in 21 patients (49%). CEUS findings were consistent with follow-up studies in 41 of the 43 patients (95%), with κ?=?0.903 (p < 0.0001), sensitivity?=?91% and specificity?=?100%, indicating that CEUS can be confidently used to differentiate benign from malignant portal vein thrombosis in the setting of chronic liver disease.  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