全文获取类型
| 收费全文 | 2669251篇 |
| 免费 | 172982篇 |
| 国内免费 | 8112篇 |
专业分类
| 耳鼻咽喉 | 35188篇 |
| 儿科学 | 87019篇 |
| 妇产科学 | 73061篇 |
| 基础医学 | 371950篇 |
| 口腔科学 | 71247篇 |
| 临床医学 | 240269篇 |
| 内科学 | 529604篇 |
| 皮肤病学 | 63739篇 |
| 神经病学 | 219848篇 |
| 特种医学 | 102237篇 |
| 外国民族医学 | 754篇 |
| 外科学 | 395411篇 |
| 综合类 | 51867篇 |
| 现状与发展 | 5篇 |
| 一般理论 | 1002篇 |
| 预防医学 | 200142篇 |
| 眼科学 | 57782篇 |
| 药学 | 193316篇 |
| 72篇 | |
| 中国医学 | 5786篇 |
| 肿瘤学 | 150046篇 |
出版年
| 2021年 | 21855篇 |
| 2019年 | 22665篇 |
| 2018年 | 30796篇 |
| 2017年 | 23764篇 |
| 2016年 | 27527篇 |
| 2015年 | 30907篇 |
| 2014年 | 42262篇 |
| 2013年 | 63001篇 |
| 2012年 | 83656篇 |
| 2011年 | 88050篇 |
| 2010年 | 53311篇 |
| 2009年 | 51205篇 |
| 2008年 | 82126篇 |
| 2007年 | 87035篇 |
| 2006年 | 88601篇 |
| 2005年 | 84585篇 |
| 2004年 | 81840篇 |
| 2003年 | 79073篇 |
| 2002年 | 76303篇 |
| 2001年 | 130140篇 |
| 2000年 | 133006篇 |
| 1999年 | 111864篇 |
| 1998年 | 31904篇 |
| 1997年 | 28438篇 |
| 1996年 | 28653篇 |
| 1995年 | 27816篇 |
| 1994年 | 25461篇 |
| 1993年 | 23785篇 |
| 1992年 | 86012篇 |
| 1991年 | 82372篇 |
| 1990年 | 79498篇 |
| 1989年 | 76747篇 |
| 1988年 | 70114篇 |
| 1987年 | 68541篇 |
| 1986年 | 64091篇 |
| 1985年 | 61032篇 |
| 1984年 | 45366篇 |
| 1983年 | 38322篇 |
| 1982年 | 22719篇 |
| 1981年 | 20208篇 |
| 1979年 | 39301篇 |
| 1978年 | 27685篇 |
| 1977年 | 23473篇 |
| 1976年 | 21712篇 |
| 1975年 | 23086篇 |
| 1974年 | 27088篇 |
| 1973年 | 25660篇 |
| 1972年 | 24039篇 |
| 1971年 | 22215篇 |
| 1970年 | 20432篇 |
排序方式： 共有10000条查询结果，搜索用时 31 毫秒
71.
J. Rodríguez-Carrio A. Martínez-Zapico I. Cabezas-Rodríguez L. Benavente Á.I. Pérez-Álvarez P. López J.B. Cannata-Andía M. Naves-Díaz A. Suárez 《Nutrition, metabolism, and cardiovascular diseases : NMCD》2019,29(2):135-143
Background and aims
Since accelerated atherosclerosis has been reported in systemic lupus erythematosus (SLE), predictive biomarkers of cardiovascular disease (CVD) are needed. Among non-traditional risk factors, bone mineral density (BMD) has been related to CVD. However, its role in SLE remains controversial. This study aims to analyze the associations of subclinical atherosclerosis with traditional and non-traditional CV risk factors.Methods and results
In a cross-sectional study, atherosclerosis burden was compared between 112 female SLE patients and 31 controls. Plaque number and carotid intima-media wall thickness (cIMT) were assessed by ultrasonography. In a retrospective study, BMD determinations obtained 5-years before the ultrasonography assessment were analyzed in a subgroup of 62 patients. Plaque frequency was increased in SLE, even in patients without CV events or carotid wall thickening. cIMT was increased in patients with CVD, positively correlated with body mass index (BMI). Interestingly, a paradoxical effect of BMI on carotid parameters was observed. Whereas underweight patients (BMI < 20) showed increased prevalence of carotid plaques with low cIMT, those with BMI > 30 showed higher cIMT and plaque burden. Overweight patients (25 < BMI<30) exhibited both elevated cIMT and plaque number. BMI was an independent predictor of BMD. In our retrospective study, patients with either clinical or subclinical CVD exhibited lower BMD levels than their CV-free counterparts. A low lumbar spine BMD independently predicted CVD development after adjusting for confounders.Conclusion
SLE was associated with a higher subclinical atherosclerosis burden, a bimodal effect being observed for BMI. Decreased BMD can be a CV risk biomarker in SLE. 相似文献72.
Francesco Grigioni Giovanni Benfari Jean-Louis Vanoverschelde Christophe Tribouilloy Jean-Francois Avierinos Francesca Bursi Rakesh M. Suri Federico Guerra Agnés Pasquet Dan Rusinaru Emanuela Marcelli Alexis Théron Andrea Barbieri Hector Michelena Siham Lazam Catherine Szymanski Vuyisile T. Nkomo Alessandro Capucci L. Bacchi-Reggiani 《Journal of the American College of Cardiology》2019,73(3):264-274
Background
Scientific guidelines consider atrial fibrillation (AF) complicating degenerative mitral regurgitation (DMR) a debated indication for surgery.Objectives
This study analyzed the prognostic/therapeutic implications of AF at DMR diagnosis and long-term.Methods
Patients were enrolled in the MIDA (Mitral Regurgitation International Database) registry, which reported the consecutive, multicenter, international experience with DMR due to flail leaflets echocardiographically diagnosed.Results
Among 2,425 patients (age 67 ± 13 years; 71% male, 67% asymptomatic, ejection fraction 64 ± 10%), 1,646 presented at diagnosis with sinus rhythm (SR), 317 with paroxysmal AD, and 462 with persistent AF. Underlying clinical/instrumental characteristics progressively worsened from SR to paroxysmal to persistent AF. During follow-up, paroxysmal and persistent AF were associated with excess mortality (10-year survival in SR and in paroxysmal and persistent AF was 74 ± 1%, 59 ± 3%, and 46 ± 2%, respectively; p < 0.0001), that persisted 20 years post-diagnosis and independently of all baseline characteristics (p values <0.0001). Surgery (n = 1,889, repair 88%) was associated with better survival versus medical management, regardless of all baseline characteristics and rhythm (adjusted hazard ratio: 0.26; 95% confidence interval: 0.23 to 0.30; p < 0.0001) but post-surgical outcome remained affected by AF (10-year post-surgical survival in SR and in paroxysmal and persistent AF was 82 ± 1%, 70 ± 4%, and 57 ± 3%, respectively; p < 0.0001).Conclusions
AF is a frequent occurrence at DMR diagnosis. Although AF is associated with older age and more severe presentation of DMR, it is independently associated with excess mortality long-term after diagnosis. Surgery is followed by improved survival in each cardiac rhythm subset, but persistence of excess risk is observed for each type of AF. Our study indicates that detection of AF, even paroxysmal, should trigger prompt consideration for surgery. 相似文献73.
K.-C. Sung D.-C. Seo S.-J. Lee M.-Y. Lee S.H. Wild C.D. Byrne 《Nutrition, metabolism, and cardiovascular diseases : NMCD》2019,29(5):489-495
Background and aims
It is not known whether non alcoholic fatty liver disease (NAFLD) is a risk factor for diabetes in non obese, non centrally-obese subjects. Our aim was to investigate relationships between fatty liver, insulin resistance and a biomarker score for liver fibrosis with incident diabetes at follow up, in subjects who were neither obese nor centrally-obese.Methods and results
As many as 70,303 subjects with a body mass index (BMI) < 25 kg/m2 and without diabetes were followed up for a maximum of 7.9 years. At baseline, fatty liver was identified by liver ultrasound, insulin resistance (IR) by homeostatic model assessment of insulin resistance (HOMA-IR) ≥2.0, and central obesity by waist circumference (waist circumference ≥90 cm (men) and ≥85 cm (women). The Fibrosis-4 (FIB-4 score) was used to estimate extent of liver fibrosis. Cox proportional hazards models adjusted for confounders were used to estimate hazard ratios (aHRs) for incident diabetes. As many as 852 incident cases of diabetes occurred during follow up (median [IQR] 3.71 [2.03] years). Mean ± SD BMI was 22.8 ± 1.8 and 21.7 ± 2.0 kg/m2 in subjects with and without diabetes at follow up. In subjects without central obesity and with fatty liver, aHRs (95% CI) for incident diabetes at follow up were 2.17 (1.56, 3.03) for men, and 2.86 (1.50,5.46) for women. Similar aHRs for incident diabetes occurred with fatty liver, IR and the highest quartile of FIB-4 combined, in men; and there was a non significant trend toward increased risk in women.Conclusions
In normal weight, non-centrally obese subjects NAFLD is an independent risk factor for incident diabetes. 相似文献74.
Otavio Berwanger Renato D. Lopes Diogo D.F. Moia Francisco A. Fonseca Lixin Jiang Shaun G. Goodman Stephen J. Nicholls Alexander Parkhomenko Oleg Averkov Carlos Tajer Germán Malaga Jose F.K. Saraiva Helio P. Guimaraes Pedro G.M. de Barros e Silva Lucas P. Damiani Renato H.N. Santos Denise M. Paisani Tamiris A. Miranda Jose C. Nicolau 《Journal of the American College of Cardiology》2019,73(22):2819-2828
BackgroundThe efficacy of ticagrelor in the long-term post–ST-segment elevation myocardial infarction (STEMI) treated with fibrinolytic therapy remains uncertain.ObjectivesThe purpose of this study was to evaluate the efficacy of ticagrelor when compared with clopidogrel in STEMI patients treated with fibrinolytic therapy.MethodsThis international, multicenter, randomized, open-label with blinded endpoint adjudication trial enrolled 3,799 patients (age <75 years) with STEMI receiving fibrinolytic therapy. Patients were randomized to ticagrelor (180-mg loading dose, 90 mg twice daily thereafter) or clopidogrel (300- to 600-mg loading dose, 75 mg daily thereafter). The key outcomes were cardiovascular mortality, myocardial infarction, or stroke, and the same composite outcome with the addition of severe recurrent ischemia, transient ischemic attack, or other arterial thrombotic events at 12 months.ResultsThe combined outcome of cardiovascular mortality, myocardial infarction, or stroke occurred in 129 of 1,913 patients (6.7%) receiving ticagrelor and in 137 of 1,886 patients (7.3%) receiving clopidogrel (hazard ratio: 0.93; 95% confidence interval: 0.73 to 1.18; p = 0.53). The composite of cardiovascular mortality, myocardial infarction, stroke, severe recurrent ischemia, transient ischemic attack, or other arterial thrombotic events occurred in 153 of 1,913 patients (8.0%) treated with ticagrelor and in 171 of 1,886 patients (9.1%) receiving clopidogrel (hazard ratio: 0.88; 95% confidence interval: 0.71 to 1.09; p = 0.25). The rates of major, fatal, and intracranial bleeding were similar between the ticagrelor and clopidogrel groups.ConclusionAmong patients age <75 years with STEMI, administration of ticagrelor after fibrinolytic therapy did not significantly reduce the frequency of cardiovascular events when compared with clopidogrel. (Ticagrelor in Patients With ST Elevation Myocardial Infarction Treated With Pharmacological Thrombolysis [TREAT]; NCT02298088) 相似文献
75.
M. Tobias Heinrichs George L. Drusano David L. Brown Michael S. Maynard Sherwin K.B. Sy Kenneth H. Rand Charles A. Peloquin Arnold Louie Hartmut Derendorf 《International journal of antimicrobial agents》2019,53(3):275-283
Introduction
There is an urgent need for new anti-tuberculosis (TB) drugs and optimization of current TB treatment. Moxifloxacin and linezolid are valuable options for the treatment of drug-resistant TB; however, it is crucial to find a dose at which these drugs not only show high efficacy but also suppress the development of further drug resistance.Methods
Activity of moxifloxacin and linezolid against Mycobacterium tuberculosis was studied in the hollow-fiber infection model system in log-phase growth under neutral pH and slow growth in an acidic environment. Doses that achieved maximum bacterial kill while suppressing the emergence of drug resistance were determined. Through Monte Carlo simulations the quantitative output of this in vitro study was bridged to the human patient population to inform optimal dosage regimens while accounting for clinical minimum inhibitory concentration (MIC) distributions.Results and Discussion
Moxifloxacin activity was significantly decreased in an acidified environment. The loss of activity was compensated by accumulation of the drug in TB lung lesions; therefore, moderate efficacy can be expected. Moxifloxacin 800 mg/day is the dose that most likely leads to resistance suppression while exerting maximum bacterial kill. Linezolid demonstrated very good activity even at a reduced pH. Linezolid 900 mg once-daily (QD) is likely to achieve a maximum killing effect and prevent the emergence of drug resistance; 600 mg QD in a robust drug regimen may have similar potential. 相似文献76.
Christos Chouaid Gérard De Pouvourville Samuel Aballéa Daria Korchagina Michael Baldwin 《Current medical research and opinion》2019,35(5):785-792
Objectives: Understanding inhaler preferences may contribute to improving adherence in COPD patients and improving long-term outcomes. This study aims to identify and quantify preferences for convenience-related inhaler attributes in French moderate-to-severe COPD patients, with discrete choice experiment (DCE) methodology.
Methods: Attributes were defined from a literature search, clinician and patient interviews: shape, dose insertion, dose preparation, dose release, dose confirmation, dose counter and reusability. An online DCE was conducted in respondents with self-reported COPD stage 2–4 recruited through a panel. The study questionnaire included twelve choice scenarios per respondent and questions on patient characteristics, treatment and disease severity. Statistical analyses used a mixed logit regression model with random effects. Utility scores were estimated for four types of inhalers: Inhaler A – soft mist inhaler; Inhaler B – reusable soft mist inhaler; Inhaler C – multi-dose dry powder inhaler; and Inhaler D – single dose dry powder inhaler.
Results: The study was completed by 153 patients (50 females); respondents were 50.4?years old on average; 13 different inhaler devices were reported. The most preferred inhaler is L-shaped, has dose preparation with capsule insertion and a dose counter, and is reusable. Inhaler profiles A and B had the highest utilities (mean of 1.2533 and 0.9578 respectively) compared to inhaler C (0.6315) and D (0.2200).
Conclusions: This study showed statistically significant results that the strongest drivers of preference in French users of inhalation devices for COPD are shape, dose counter and reusability. Convenience-related characteristics are important to patients and should be taken into account by clinicians prescribing these devices. 相似文献
77.
C. Ludes A. Labani F. Severac M.Y. Jeung P. Leyendecker C. Roy M. Ohana 《Diagnostic and interventional imaging》2019,100(2):85-93
Purpose
To qualitatively and quantitatively compare unenhanced ultra-low-dose chest computed tomography (ULD-CT) acquired at 80 kVp and 135 kVp.Materials and methods
Fifty-one patients referred for unenhanced chest CT were prospectively included. There were 29 men and 22 women, with a mean age of 64.7 ± 11.6 (SD) years (range: 35–91 years) and a mean body mass index of 26.2 ± 6.3 (SD) (range: 17–54.9). All patients underwent two different ULD-CT protocols (80 kVp-40 mA and 135 kVp-10 mA). Image quality of both ULD-CT examinations using a 5-level scale as well as assessability of 6 predetermined lung parenchyma lesions were blindly evaluated by three radiologists and compared using a logistic regression model. Image noise of the two protocols was compared with Wilcoxon signed-rank test.Results
The mean dose-length product at 80 kVp and at 135 kVp were 14.7 ± 1.8 (SD) mGy.cm and 15.6 ± 1.9 (SD) mGy.cm, respectively (P < 0.001). Image noise was significantly lower at 135 kVp (58.9 ± 12.4) than at 80 kVp (74.7 ± 14.5) (P < 0.001). For all readers and for all examinations, the 135 kVp protocol yielded better image quality than 80 kVp protocol, with a mean qualitative score of 4.5 ± 0.7 versus 3.9 ± 0.8 (P < 0.001). The 135 kVp protocol was significantly more often of diagnostic quality than the 80 kvp protocol (92.3% versus 77.8%, respectively) (P < 0.001) and was less prone to image quality deterioration in obese patients. Parenchymal lesions were never better depicted on the 80 kVp protocol than with the 135 kVp protocol.Conclusion
Unenhanced chest ULD-CT should be acquired at a high kilovoltage and low current, such as 135 kVp-10 mA, over a low kilovoltage and high current protocol. 相似文献78.
Andrew J Lindford Heikki Mäkisalo Hannu Jalanko Jouni Lauronen Veli-Jukka Anttila Susanna Juteau Antti-Jussi Ämmälä Anna Eskola Samuli Saarni Helena Isoniemi Antti Mäkitie Patrik Lassus 《Journal of plastic, reconstructive & aesthetic surgery》2019,72(2):173-180
Aim
We herein describe the establishment of the Helsinki Vascularized Composite Allotransplantation (VCA) program and its execution in the first two face transplant cases.Methods & patients
The Helsinki VCA program initially required the fulfillment of legal, hospital, financial, and ethical requirements. Thereafter, the assembling of a multidisciplinary team commenced. A team of Plastic, maxillofacial and ENT surgeons comprise the facial VCA team. The protocol involves collaboration with the Solid Organ Transplant (SOT) team, transplant immunology, immunosuppression, microbiology, psychiatric evaluation, well-defined VCA indications and informed consent. Between 2011 and 2017 two patients were selected for transplantation. Both patients had a severe composite facial deformity involving the maxilla and mandible following earlier ballistic injury.Results
Patient 1 was a 35 year-old male who underwent successful near total face transplantation in February 2016 and at 30 months he has a good aesthetic outcome with symmetrical restoration of the central face and good sensory and symmetrical motor functional outcomes. Patient 2 was a 58 year-old male who underwent full face transplantation in March 2018 and at 5 months he has recovered without major problems.Conclusion
A successful facial VCA program requires a well-prepared research protocol, experts from multiple specialties and careful patient selection. The establishment of the Helsinki VCA program required long and thorough planning and resulted in the first two Nordic face transplantation cases. This protocol now forms the platform (as a proof of concept) for other types of vascularized composite allotransplantations. 相似文献79.
80.
V. Jenkins I. Solis-Trapala H. Payne M. Mason L. Fallowfield S. May L. Matthews S. Catt 《Clinical oncology (Royal College of Radiologists (Great Britain))》2019,31(2):99-107