全文获取类型
| 收费全文 | 1166548篇 |
| 免费 | 67151篇 |
| 国内免费 | 4663篇 |
专业分类
| 耳鼻咽喉 | 16236篇 |
| 儿科学 | 35389篇 |
| 妇产科学 | 32479篇 |
| 基础医学 | 162216篇 |
| 口腔科学 | 33168篇 |
| 临床医学 | 93010篇 |
| 内科学 | 238458篇 |
| 皮肤病学 | 26321篇 |
| 神经病学 | 92279篇 |
| 特种医学 | 42838篇 |
| 外国民族医学 | 356篇 |
| 外科学 | 170105篇 |
| 综合类 | 24604篇 |
| 现状与发展 | 4篇 |
| 一般理论 | 306篇 |
| 预防医学 | 93322篇 |
| 眼科学 | 26633篇 |
| 药学 | 84966篇 |
| 57篇 | |
| 中国医学 | 4574篇 |
| 肿瘤学 | 61041篇 |
出版年
| 2021年 | 12405篇 |
| 2019年 | 12645篇 |
| 2018年 | 17502篇 |
| 2017年 | 12640篇 |
| 2016年 | 13167篇 |
| 2015年 | 15145篇 |
| 2014年 | 20438篇 |
| 2013年 | 30149篇 |
| 2012年 | 42641篇 |
| 2011年 | 45365篇 |
| 2010年 | 26339篇 |
| 2009年 | 23343篇 |
| 2008年 | 40162篇 |
| 2007年 | 42492篇 |
| 2006年 | 41926篇 |
| 2005年 | 41086篇 |
| 2004年 | 38405篇 |
| 2003年 | 36708篇 |
| 2002年 | 35651篇 |
| 2001年 | 47751篇 |
| 2000年 | 49450篇 |
| 1999年 | 41830篇 |
| 1998年 | 11552篇 |
| 1997年 | 10396篇 |
| 1996年 | 10128篇 |
| 1995年 | 9370篇 |
| 1994年 | 8910篇 |
| 1992年 | 30944篇 |
| 1991年 | 29382篇 |
| 1990年 | 28730篇 |
| 1989年 | 27336篇 |
| 1988年 | 25479篇 |
| 1987年 | 24917篇 |
| 1986年 | 24004篇 |
| 1985年 | 22758篇 |
| 1984年 | 16977篇 |
| 1983年 | 14485篇 |
| 1982年 | 8658篇 |
| 1979年 | 15900篇 |
| 1978年 | 11083篇 |
| 1977年 | 9425篇 |
| 1976年 | 8956篇 |
| 1975年 | 9900篇 |
| 1974年 | 11911篇 |
| 1973年 | 11456篇 |
| 1972年 | 10848篇 |
| 1971年 | 10057篇 |
| 1970年 | 9645篇 |
| 1969年 | 9171篇 |
| 1968年 | 8832篇 |
排序方式： 共有10000条查询结果，搜索用时 31 毫秒
31.
Markel Rico-González Fabio Yuzo Nakamura Felipe Arruda Moura José Pino-Ortega 《Research in sports medicine (Print)》2020,28(2):279-292
ABSTRACTThe aim of the study was to assess the use of different positioning systems and sampling frequencies to measure spatial-positioning variables in team sports. Articles were selected when the sampling frequency was detailed. 2,194 articles were identified and 59 works were selected for the systematic review. The sampling frequency used to measure tactical behaviour differed considerably among studies. For Global Navigation Satellite System, the sampling frequency ranged from 5- to 15 Hz for raw data, the most commonly used sampling frequency being 5 Hz. For Optic-based tracking systems, the sampling frequency ranged from 10- to 30 Hz. For Local Position System, the sampling frequency ranged from 45- to 100 Hz, the most commonly used sampling frequency being 42 Hz and 57.7 Hz. There is no common criterion in the sampling frequency used to measure each tactical variable. Further studies should investigate the impact of the sampling frequency on the measurement of the tactical variables. 相似文献
32.
Karla S. Romero-Aguilar Ivonne M. Arciniega-Martínez Eunice D. Farfán-García Rafael Campos-Rodríguez 《Expert opinion on therapeutic patents》2019,29(5):339-351
Introduction: Boron-containing compounds induce effects on immune responses. Such effects are interesting to the biomedical field for the development of therapeutic tools to modulate the immune system.
Areas covered: The scope of BCC use to modify immune responses is expanding, mainly with regard to inflammatory diseases. The information was organized to demonstrate the breadth of reported effects. BCCs act as modulators of innate and adaptive immunity, with the former including regulation of cluster differentiation and cytokine production. In addition, BCCs exert effects on inflammation induced by infectious and noninfectious agents, and there are also reports regarding their effects on mechanisms involving hypersensitivity and transplants. Finally, the authors discuss the beneficial effects of BCCs on pathologies involving various targets and mechanisms.
Expert opinion: Some BCCs are currently used as drugs in humans. The mechanisms by which these BCCs modulate immune responses, as well as the required structure–activity relationship for each observed mechanism of action, should be clarified. The former will allow for the development of improved immunomodulatory drugs with extensive applications in medicine. Patenting trends involve claims concerning the synthesis and actions of identified molecules with a defined profile regarding cytokines, cell differentiation, proliferation, and antibody production. 相似文献
33.
Chahine C. Assi Hanane B. Barakat Jacques H. Caton Elie N. Najjar Camille T. Samaha Kaissar F. Yammine 《The Journal of arthroplasty》2019,34(2):333-337
Background
The dual mobility cups (DMCs) were shown to reduce dislocation rate following total hip arthroplasty for any etiology, including femoral neck fractures. No reported studies evaluating DMC results for femoral neck fracture in a Middle Eastern population were found in the literature.Methods
This study aims to look for mortality rate, clinical, and functional outcomes in a population having specific rituals involving extreme hip positions as part of their daily activities.Results
Of an initial sample of 174 patients (177 operated hips), 18 (10.3%) patients (20 hips) died after a mean of 39.6 ± 13.8 months (ranging from 2 to 49 months) with only 3 (1.7%) during the first post-operative year. Twelve patients (13 hips) were lost to follow-up and 19 patients (19 hips) had their radiological data incomplete. In the final sample of 125 patients (125 hips), no dislocation, aseptic loosening, or infection was encountered. The mean modified Hip Harris Score was of 94.8 ± 8.4. The mean modified Hip Harris Score of 40 patients who used to practice regularly oriental sitting position or prayers was 94.1 ± 3.1. After surgery, 36 of these 40 patients (90%) described their hip as “a forgotten hip.” Multivariate analyses found correlation only between mortality and cardiovascular co-morbidities.Conclusion
DMC implants showed excellent clinical and functional results. The majority of patients having rituals and customs involving extreme hip positions were able to resume their daily activities. The observed low mortality rate should incite future research to investigate its correlation with the use of DMCs. 相似文献34.
J.C. Rodríguez-Sanjuán N. Ruiz E. Miñambres E. Toledo M. González-Noriega R. Fernández-Santiago F. Castillo 《Transplantation proceedings》2019,51(1):12-19
Background
Liver transplantation from donors after either controlled or uncontrolled cardiac death (DCD) is associated with considerable rates of primary nonfunction (PNF) and ischemic cholangiopathy (IC). Normothermic regional perfusion (NRP) could significantly reduce such rates.Methods
Retrospective study to analyze short-term (mortality, PNF, vascular complications) and long-term (IC, survival) complications in 11 liver transplants from controlled DCDs using NRP with extracorporeal membrane oxygenation (ECMO) (group 1). They were compared with 51 patients transplanted with grafts from donors after brain death (DBD) (group 2). Mean recipient age, sex, and Model for End-stage Liver Disease (MELD) score were not significantly different.Results
In group 1, mean functional warm ischemia time was 15.8 (range, 7–40) minutes and 94.1 (range, 20–150) minutes on NRP. The ischemic damage was minimal, as shown by the slight alanine aminotransferase (ALT) and aspartate aminotransferase (AST) rises in the donor serum after 1 hour on NRP and similar rises 24 hours after transplantation in both groups. No patient had IC or acute renal failure. No significant difference was found between the groups for vascular or biliary complications. One group 1 patient had PNF (9.1%), resulting in death. Overall retransplantation and in-hospital death rates were 8.1% and 4.8%, respectively, with no significant difference between groups. Estimated mean survival was 24.6 (95% confidence interval [CI], 20.2–29.1) months in group 1 and 32.3 (95% CI, 30.4–34.2) months in group 2 (not a statistically significant difference).Conclusion
In our experience, liver transplants from controlled DCDs using NRP with ECMO is associated with a low risk of PNF and IC, with short- and long-term results comparable to those in DBD transplants. 相似文献35.
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36.
Partha Sardar Deepak L. Bhatt Ajay J. Kirtane Kevin F. Kennedy Saurav Chatterjee Jay Giri Peter A. Soukas William B. White Sahil A. Parikh Herbert D. Aronow 《Journal of the American College of Cardiology》2019,73(13):1633-1642
Background
There are conflicting data regarding the relative effectiveness of renal sympathetic denervation (RSD) in patients with hypertension.Objectives
The purpose of this study was to evaluate the blood pressure (BP) response after RSD in sham-controlled randomized trials.Methods
Databases were searched through June 30, 2018. Randomized trials (RCTs) with ≥50 patients comparing catheter-based RSD with a sham control were included. The authors calculated summary treatment estimates as weighted mean differences (WMD) with 95% confidence intervals (CIs) using random-effects meta-analysis.Results
The analysis included 977 patients from 6 trials. The reduction in 24-h ambulatory systolic blood pressure (ASBP) was significantly greater for patients treated with RSD than sham procedure (WMD ?3.65 mm Hg, 95% CI: ?5.33 to ?1.98; p < 0.001). Compared with sham, RSD was also associated with a significant decrease in daytime ASBP (WMD ?4.07 mm Hg, 95% CI: ?6.46 to ?1.68; p < 0.001), office systolic BP (WMD ?5.53 mm Hg, 95% CI: ?8.18 to ?2.87; p < 0.001), 24-h ambulatory diastolic BP (WMD ?1.71 mm Hg, 95% CI: ?3.06 to ?0.35; p = 0.01), daytime ambulatory diastolic BP (WMD ?1.57 mm Hg, 95% CI: ?2.73 to ?0.42; p = 0.008), and office diastolic BP (WMD ?3.37 mm Hg, 95% CI: ?4.86 to ?1.88; p < 0.001). Compared with first-generation trials, a significantly greater reduction in daytime ASBP was observed with RSD in second-generation trials (6.12 mm Hg vs. 2.14 mm Hg; p interaction = 0.04); however, this interaction was not significant for 24-h ASBP (4.85 mm Hg vs. 2.23 mm Hg; p interaction = 0.13).Conclusions
RSD significantly reduced blood pressure compared with sham control. Results of this meta-analysis should inform the design of larger, pivotal trials to evaluate the long-term efficacy and safety of RSD in patients with hypertension. 相似文献37.
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
38.
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
39.
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40.