收费全文 | 235375篇 |
免费 | 11248篇 |
国内免费 | 397篇 |
耳鼻咽喉 | 3064篇 |
儿科学 | 7341篇 |
妇产科学 | 4773篇 |
基础医学 | 33851篇 |
口腔科学 | 5339篇 |
临床医学 | 18655篇 |
内科学 | 51989篇 |
皮肤病学 | 6279篇 |
神经病学 | 21120篇 |
特种医学 | 7042篇 |
外国民族医学 | 105篇 |
外科学 | 29118篇 |
综合类 | 980篇 |
一般理论 | 62篇 |
预防医学 | 21383篇 |
眼科学 | 4563篇 |
药学 | 16509篇 |
中国医学 | 708篇 |
肿瘤学 | 14139篇 |
2023年 | 1251篇 |
2022年 | 890篇 |
2021年 | 3490篇 |
2020年 | 2081篇 |
2019年 | 3918篇 |
2018年 | 7474篇 |
2017年 | 4895篇 |
2016年 | 4891篇 |
2015年 | 5486篇 |
2014年 | 5732篇 |
2013年 | 9241篇 |
2012年 | 16070篇 |
2011年 | 16049篇 |
2010年 | 7996篇 |
2009年 | 5964篇 |
2008年 | 13812篇 |
2007年 | 14771篇 |
2006年 | 13589篇 |
2005年 | 13482篇 |
2004年 | 12626篇 |
2003年 | 11528篇 |
2002年 | 10910篇 |
2001年 | 6161篇 |
2000年 | 6235篇 |
1999年 | 5552篇 |
1998年 | 908篇 |
1997年 | 772篇 |
1996年 | 723篇 |
1992年 | 3221篇 |
1991年 | 2891篇 |
1990年 | 2753篇 |
1989年 | 2510篇 |
1988年 | 2376篇 |
1987年 | 2207篇 |
1986年 | 2100篇 |
1985年 | 1900篇 |
1984年 | 1406篇 |
1983年 | 1195篇 |
1982年 | 673篇 |
1979年 | 1213篇 |
1978年 | 849篇 |
1977年 | 800篇 |
1975年 | 808篇 |
1974年 | 989篇 |
1973年 | 999篇 |
1972年 | 938篇 |
1971年 | 932篇 |
1970年 | 864篇 |
1969年 | 912篇 |
1968年 | 788篇 |
Prolonged mechanical ventilation (MV) is a major complication following cardiac surgery. We conducted a secondary analysis of the Transfusion Requirements in Cardiac Surgery (TRICTS) III trial to describe MV duration, identify factors associated with prolonged MV, and examine associations of prolonged MV with mortality and complications.
MethodsFour thousand, eight hundred and nine participants undergoing cardiac surgery at 71 hospitals worldwide were included. Prolonged MV was defined based on the Society of Thoracic Surgeons definition as MV lasting 24 hr or longer. Adjusted associations of patient and surgical factors with prolonged MV were examined using multivariable logistic regression. Associations of prolonged MV with complications were assessed using odds ratios, and adjusted associations between prolonged MV and mortality were evaluated using multinomial regression. Associations of shorter durations of MV with survival and complications were explored.
ResultsProlonged MV occurred in 15% (725/4,809) of participants. Prolonged MV was associated with surgical factors indicative of complexity, such as previous cardiac surgery, cardiopulmonary bypass duration, and separation attempts; and patient factors such as critical preoperative state, left ventricular impairment, renal failure, and pulmonary hypertension. Prolonged MV was associated with perioperative but not long-term complications. After risk adjustment, prolonged MV was associated with perioperative mortality; its association with long-term mortality among survivors was weaker. Shorter durations of MV were not associated with increased risk of mortality or complications.
ConclusionIn this substudy of the TRICS III trial, prolonged MV was common after cardiac surgery and was associated with patient and surgical risk factors. Although prolonged MV showed strong associations with perioperative complications and mortality, it was not associated with long-term complications and had weaker association with long-term mortality among survivors.
Study registrationwww.ClinicalTrials.gov (NCT02042898); registered 23 January 2014. This is a substudy of the Transfusion Requirements in Cardiac Surgery (TRICS) III trial.
相似文献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Abbreviations: CONCEA: National Council for the Control of Animal Experimentation; GEPR: genetically epilepsy-prone rats; WAR: Wistar Audiogenic Rat. 相似文献
Objectives
This study reported a hospital outbreak due to an extensively drug-resistant (XDR) OXA-72-producing strain of Acinetobacter baumannii (A. baumannii).Methods and Results
The isolates were found to be genotypically indistinguishable by whole-genome multiple locus sequence typing, and to belong to the international clonal complex CC2. One of these isolates sequentially developed a high resistance to colistin and rifampicin under treatment, as a result of mutations in genes pmrB and rpoB, respectively. The blaOXA-72 gene was localised on a 10-kb transferable plasmid, named pAB-STR-1, whose sequence is nearly identical to that of another plasmid previously found in Lithuanian strains, pAB120.Conclusion
This report highlighted the need to carefully monitor the emergence of colistin and rifampicin resistance in patients treated for infections with multidrug-resistant A. baumannii. 相似文献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