全文获取类型
收费全文 | 38445篇 |
免费 | 2030篇 |
国内免费 | 147篇 |
专业分类
耳鼻咽喉 | 518篇 |
儿科学 | 914篇 |
妇产科学 | 744篇 |
基础医学 | 4890篇 |
口腔科学 | 2201篇 |
临床医学 | 2742篇 |
内科学 | 9929篇 |
皮肤病学 | 939篇 |
神经病学 | 3118篇 |
特种医学 | 797篇 |
外科学 | 5707篇 |
综合类 | 236篇 |
一般理论 | 13篇 |
预防医学 | 2836篇 |
眼科学 | 691篇 |
药学 | 2113篇 |
中国医学 | 135篇 |
肿瘤学 | 2099篇 |
出版年
2024年 | 30篇 |
2023年 | 265篇 |
2022年 | 622篇 |
2021年 | 1401篇 |
2020年 | 741篇 |
2019年 | 1093篇 |
2018年 | 1277篇 |
2017年 | 837篇 |
2016年 | 933篇 |
2015年 | 1063篇 |
2014年 | 1583篇 |
2013年 | 1921篇 |
2012年 | 3155篇 |
2011年 | 3277篇 |
2010年 | 1875篇 |
2009年 | 1569篇 |
2008年 | 2648篇 |
2007年 | 2665篇 |
2006年 | 2588篇 |
2005年 | 2506篇 |
2004年 | 2131篇 |
2003年 | 1922篇 |
2002年 | 1710篇 |
2001年 | 191篇 |
2000年 | 140篇 |
1999年 | 221篇 |
1998年 | 289篇 |
1997年 | 224篇 |
1996年 | 200篇 |
1995年 | 190篇 |
1994年 | 146篇 |
1993年 | 110篇 |
1992年 | 104篇 |
1991年 | 85篇 |
1990年 | 52篇 |
1989年 | 39篇 |
1988年 | 46篇 |
1987年 | 42篇 |
1986年 | 44篇 |
1985年 | 52篇 |
1984年 | 55篇 |
1983年 | 54篇 |
1982年 | 43篇 |
1981年 | 50篇 |
1980年 | 62篇 |
1979年 | 32篇 |
1978年 | 36篇 |
1977年 | 45篇 |
1976年 | 28篇 |
1974年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
OBJECTIVE: Libman-Sacks endocarditis in patients with systemic lupus erythematosus (SLE) is complicated with thromboembolism, severe valve regurgitation, need for high-risk valve surgery, or death. Transesophageal echocardiography (TEE) is highly accurate for detection of valvular heart disease, but there are no prospective randomized controlled series comparing transthoracic echocardiography (TTE) to TEE for detection of Libman-Sacks endocarditis. METHODS: Eighty-one patients with SLE (73 women, 8 men) with a mean age of 39 +/- 11 years and 75 healthy volunteers (40 women, 35 men) with a mean age of 35 +/- 9 years underwent paired TTE and TEE to detect valve vegetations, thickening, or >or= moderate mitral, tricuspid, or pulmonic >or= mild aortic regurgitation. Paired TTE and TEE studies of patients and controls were randomized and interpreted by an experienced observer unaware of subjects' data. RESULTS: Libman-Sacks endocarditis: (1) was more common in patients than in controls by both TTE and TEE (p < 0.001); and (2) was more commonly detected by TEE than by TTE (p = 0.05); (3) TTE and TEE demonstrated poor agreement rates (kappa 0.02-0.54); and (4) considering TEE as the standard, TTE demonstrated a low sensitivity (63% overall, 11% for valve vegetations), low specificity (58%), low negative predictive value (40%), and a moderate positive predictive value (78%) for detection of Libman-Sacks endocarditis. CONCLUSION: TEE is superior to TTE for detection of Libman-Sacks endocarditis and should be considered either as complement to a nondiagnostic TTE or as the initial test in patients with SLE with suspected cardioembolism, acute or subacute Libman-Sacks endocarditis with moderate or worse valve dysfunction, or superimposed infective endocarditis. 相似文献
992.
Carlos Collet Yosuke Miyazaki Nicola Ryan Taku Asano Erhan Tenekecioglu Jeroen Sonck Daniele Andreini Manel Sabate Salvatore Brugaletta Rodney H. Stables Antonio Bartorelli Robbert J. de Winter Yuki Katagiri Ply Chichareon Giovanni Luigi De Maria Pannipa Suwannasom Rafael Cavalcante Hans Jonker Patrick W. Serruys 《Journal of the American College of Cardiology》2018,71(24):2756-2769
Background
The functional SYNTAX score (FSS) has been shown to improve the discrimination for major adverse cardiac events compared with the anatomic SYNTAX score (SS) while reducing interobserver variability. However, evidence supporting the noninvasive FSS in patients with multivessel coronary artery disease (CAD) is scarce.Objectives
The purpose of this study was to assess the feasibility of and validate the noninvasive FSS derived from coronary computed tomography angiography (CTA) with fractional flow reserve (FFRCT) in patients with 3-vessel CAD.Methods
The CTA-SS was calculated in patients with 3-vessel CAD included in the SYNTAX II (SYNergy between percutaneous coronary intervention with TAXus and cardiac surgery II) study. The noninvasive FSS was determined by including only ischemia-producing lesions (FFRCT ≤0.80). SS derived from different imaging modalities were compared using the Bland-Altman and Passing-Bablok method, and the agreement on the SS tertiles was investigated with Cohen’s Kappa. The risk reclassification was compared between the noninvasive and invasive physiological assessment, and the diagnostic accuracy of FFRCT was assessed by the area under the receiver-operating characteristic curve using instantaneous wave-free ratio as a reference.Results
The CTA-SS was feasible in 86% of patients (66 of 77), whereas the noninvasive FSS was feasible in 80% (53 of 66). The anatomic SS was overestimated by CTA compared with conventional angiography (27.6 ± 6.4 vs. 25.3 ± 6.9; p < 0.0001) whereas the calculation of the FSS yielded similar results between the noninvasive and invasive imaging modalities (21.6 ± 7.8 vs. 21.2 ± 8.8; p = 0.589). The noninvasive FSS reclassified 30% of patients from the high- and intermediate-SS tertiles to the low-risk tertile, whereas invasive FSS reclassified 23% of patients from the high- and intermediate-SS tertiles to the low-risk tertile. The agreement on the classic SS tertiles based on Kappa statistics was slight for the anatomic SS (Kappa = 0.19) and fair for the FSS (Kappa = 0.32). The diagnostic accuracy of FFRCT to detect functional significant stenosis based on an instantaneous wave-free ratio ≤0.89 revealed an area under the receiver-operating characteristics curve of 0.85 (95% CI: 0.79 to 0.90) with a sensitivity of 95% (95% CI: 89% to 98%), specificity of 61% (95% CI: 48% to 73%), positive predictive value of 81% (95% CI: 76% to 86%), and negative predictive value of 87% (95% CI: 74% to 94%).Conclusions
Calculation of the noninvasive FSS is feasible and yielded similar results to those obtained with invasive pressure-wire assessment. The agreement on the SYNTAX score tertile classification improved with the inclusion of the functional component from slight to fair agreement. FFRCT has good accuracy in detecting functionally significant lesions in patients with 3-vessel CAD. (A Trial to Evaluate a New Strategy in the Functional Assessment of 3-Vessel Disease Using SYNTAX II Score in Patients Treated With PCI; NCT02015832) 相似文献993.
Classification of Sphenoid Sinus Pneumatization: Relevance for Endoscopic Skull Base Surgery
下载免费PDF全文
![点击此处可从《The Laryngoscope》网站下载免费的PDF全文](/ch/ext_images/free.gif)
994.
Hypoglossal nerve stimulation in the treatment of obstructive sleep apnea: A systematic review and meta‐analysis
下载免费PDF全文
![点击此处可从《The Laryngoscope》网站下载免费的PDF全文](/ch/ext_images/free.gif)
995.
Santiago Gonzalez-Ayora Carlos Pastor Hector Guadalajara Jose Manuel Ramirez Pablo Royo Elizabeth Redondo Antonio Arroyo Pedro Moya Damian Garcia-Olmo 《International journal of colorectal disease》2016,31(9):1625-1631
Purpose
ERAS (enhanced recovery after surgery) programs have proven to reduce morbidity and hospital stay in colorectal surgery. However, the feasibility of these programs in elderly patients has been questioned. The aim of this study is to assess the implementation and outcomes of an ERAS program for colorectal cancer in elderly patients.Methods
This is a multicenter observational study of a cohort of elderly patients undergoing colorectal surgery within an ERAS program. A total of 188 consecutive patients over 70 years who underwent elective colorectal surgery within an ERAS program at three institutions during a 2-year period were included. The compliance with the ERAS protocol interventions was measure. Complications were evaluated according to Clavien-Dindo classification. Data on length of stay and readmission rates were analyzed.Results
Early intake and early mobilization were the most successfully carried out interventions. There was a global compliance rate of 56 % of patients for whom compliance was achieved with all measured interventions. The median hospital length of stay was 6 days. Almost 60 % of patients had no complications, 24 % had minor complications while 13 % had major complications; of them, 8 % patients were reoperated. The readmission rate was 6.4 %.Conclusions
ERAS after colorectal surgery in elderly patients presents as safe and feasible based on good reported outcomes of compliance rates, complications, readmissions, and needs for reoperation.996.
Carlos Mota Dario Puppi Federica Chiellini Emo Chiellini 《Journal of tissue engineering and regenerative medicine》2015,9(3):174-190
‘Additive manufacturing’ (AM) refers to a class of manufacturing processes based on the building of a solid object from three‐dimensional (3D) model data by joining materials, usually layer upon layer. Among the vast array of techniques developed for the production of tissue‐engineering (TE) scaffolds, AM techniques are gaining great interest for their suitability in achieving complex shapes and microstructures with a high degree of automation, good accuracy and reproducibility. In addition, the possibility of rapidly producing tissue‐engineered constructs meeting patient's specific requirements, in terms of tissue defect size and geometry as well as autologous biological features, makes them a powerful way of enhancing clinical routine procedures. This paper gives an extensive overview of different AM techniques classes (i.e. stereolithography, selective laser sintering, 3D printing, melt–extrusion‐based techniques, solution/slurry extrusion‐based techniques, and tissue and organ printing) employed for the development of tissue‐engineered constructs made of different materials (i.e. polymeric, ceramic and composite, alone or in combination with bioactive agents), by highlighting their principles and technological solutions. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
997.
Jos Abelln-Huerta Juan Carlos Bonaque-Gonzlez Ramn Rubio-Patn Jos García-Gmez Santiago Egea-Beneyto Federico Soria-Arcos Luciano Consuegra-Snchez Rosa María Soto-Ruiz Jos Luis Ramos-Martín Juan Antonio Castillo-Moreno 《Arquivos brasileiros de cardiologia》2020,115(2):253
BackgroundEchocardiography is essential for the diagnosis and quantification of aortic regurgitation (AR). Velocity-time integral (VTI) of AR flow could be related to AR severity.ObjectiveThis study aims to assess whether VTI is an echocardiographic marker of AR severity.MethodsWe included all patients with moderate or severe native AR and sinus rhythm who visited our imaging laboratory from January to October 2016. All individuals underwent a complete echocardiogram with AR VTI measurement. The association between VTI and AR severity was analyzed by logistic regression and multivariate regression models. A p-value<0,05 was considered statistically significant.ResultsAmong the 62 patients included (68.5±14.9 years old; 64.5%: moderate AR; 35.5%: severe AR), VTI was higher in individuals with moderate AR compared to those with severe AR (2.2±0.5 m vs. 1.9±0.5 m, p=0.01). Patients with severe AR presented greater values of left ventricular end-diastolic diameter (LVEDD) (56.1±7.1 mm vs. 47.3±9.6 mm, p=0.001), left ventricular end-diastolic volume (LVEDV) (171±36.5 mL vs. 106±46.6 mL, p<0.001), effective regurgitant orifice (0.44±0.1 cm2vs. 0.18±0.1 cm2, p=0.002), and regurgitant volume (71.3±25.7 mL vs. 42.5±10.9 mL, p=0.05), as well as lower left ventricular ejection fraction (LVEF) (54.1±11.2% vs. 63.2±13.3%, p=0.012). The VTI proved to be a marker of AR severity, irrespective of LVEDD, LVEDV, and LVEF (odds ratio 0.160, p=0.032) and of heart rate and diastolic blood pressure (DBP) (odds ratio 0.232, p=0.044).ConclusionsThe VTI of AR flow was inversely associated with AR severity regardless of left ventricular diameter and volume, heart rate, DBP, and LVEF. VTI could be a marker of AR severity in patients with native AR and sinus rhythm. (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0) 相似文献
998.
999.
Funez MI Ferrari LF Duarte DB Sachs D Cunha FQ Lorenzetti BB Parada CA Ferreira SH 《Proceedings of the National Academy of Sciences of the United States of America》2008,105(49):19038-19043
Previous work from our group showed that intrathecal (i.t.) administration of substances such as glutamate, NMDA, or PGE2 induced sensitization of the primary nociceptive neuron (PNN hypernociception) that was inhibited by a distal intraplantar (i.pl.) injection of either morphine or dipyrone. This pharmacodynamic phenomenon is referred to in the present work as “teleantagonism”. We previously observed that the antinociceptive effect of i.t. morphine could be blocked by injecting inhibitors of the NO signaling pathway in the paw (i.pl.), and this effect was used to explain the mechanism of opioid-induced peripheral analgesia by i.t. administration. The objective of the present investigation was to determine whether this teleantagonism phenomenon was specific to this biochemical pathway (NO) or was a general property of the PNNs. Teleantagonism was investigated by administering test substances to the two ends of the PNN (i.e., to distal and proximal terminals; i.pl. plus i.t. or i.t. plus i.pl. injections). We found teleantagonism when: (i) inhibitors of the NO signaling pathway were injected distally during the antinociception induced by opioid agonists; (ii) a nonselective COX inhibitor was tested against PNN sensitization by IL-1β; (iii) selective opioid-receptor antagonists tested against antinociception induced by corresponding selective agonists. Although the dorsal root ganglion seems to be an important site for drug interactions, the teleantagonism phenomenon suggests that, in PNNs, a local sensitization spreads to the entire cell and constitutes an intriguing and not yet completely understood pharmacodynamic property of this group of neurons. 相似文献
1000.
Glória Abreu Carlos Galvão Braga João Costa Pedro Azevedo Jorge Marques 《Revista portuguesa de cardiologia》2018,37(8):707-713