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   1756篇
  免费   69篇
  国内免费   35篇
耳鼻咽喉   27篇
儿科学   50篇
妇产科学   18篇
基础医学   107篇
口腔科学   10篇
临床医学   272篇
内科学   393篇
皮肤病学   239篇
神经病学   195篇
特种医学   33篇
外科学   189篇
综合类   112篇
预防医学   86篇
眼科学   16篇
药学   98篇
中国医学   11篇
肿瘤学   4篇
  2024年   2篇
  2023年   55篇
  2022年   99篇
  2021年   164篇
  2020年   123篇
  2019年   139篇
  2018年   111篇
  2017年   82篇
  2016年   73篇
  2015年   47篇
  2014年   132篇
  2013年   152篇
  2012年   65篇
  2011年   92篇
  2010年   61篇
  2009年   67篇
  2008年   59篇
  2007年   55篇
  2006年   43篇
  2005年   41篇
  2004年   36篇
  2003年   30篇
  2002年   19篇
  2001年   11篇
  2000年   16篇
  1999年   12篇
  1998年   16篇
  1997年   11篇
  1996年   15篇
  1995年   5篇
  1994年   4篇
  1993年   4篇
  1991年   2篇
  1990年   1篇
  1989年   3篇
  1988年   5篇
  1987年   1篇
  1985年   1篇
  1984年   2篇
  1982年   2篇
  1980年   1篇
  1976年   1篇
排序方式: 共有1860条查询结果,搜索用时 31 毫秒
101.
BackgroundNon-alcoholic fatty liver disease (NAFLD) patients represent a vulnerable population that may be susceptible to more severe COVID-19. Moreover, not only the underlying NAFLD may influence the progression of COVID-19, but the COVID-19 may affect the clinical course of NAFLD as well. However, comprehensive evidence on clinical outcomes in patients with NAFLD is not well characterized.ObjectivesTo systematically review and meta-analysis the evidence on clinical outcomes in NAFLD patients with COVID-19.MethodsMEDLINE, EMBASE, and Cochrane Central were searched from inception through November 2020. Epidemiological studies assessing the clinical outcomes in COVID-19 patients with NAFLD were included. Newcastle-Ottawa Scale (NOS) was used to assess study quality. Generic inverse variance method using RevMan was used to determine the pooled estimates using the random-effects model.ResultsFourteen studies consisting of 1851 NAFLD patients, were included. Significant heterogeneity was observed among the studies, and studies were of moderate to high quality [mean, (range):8 (6, 8)]. For NAFLD patients, the adjusted odds ratio (aOR) for the severe COVID-19 was 2.60 (95%CI:2.24–3.02; p < 0.001) (studies,n:8), aOR for admission to ICU due to COVID-19 was 1.66 (95%CI:1.26–2.20; p < 0.001) (studies,n:2), and aOR for mortality for was 1.01 (95%CI:0.65–1.58; p = 0.96) (studies,n:2).ConclusionsAn increased risk of severe COVID-19 infection and admission to ICU due to COVID-19 with no difference in mortality was observed between NAFLD and non-NAFLD patients. Future studies should include the mortality outcome to conclusively elucidate the impact of NAFLD in patients with COVID-19.  相似文献   
102.
AimsThis meta-analysis aims to analyze the association of calcium channel blocker (CCB) use with COVID-19 clinical outcomes.MethodsPubMed, ProQuest, Science Direct, Scopus, and medRxiv databases were searched systematically in a limited period. The primary outcome was mortality.ResultsA total of 119,298 patients from 31 eligible studies were included. Pooled analysis of the random-effect model revealed CCB was not associated with reduced mortality (OR = 1.21 [95%CI: 0.98–1.49], p = 0.08). Interestingly, subgroup analysis in hypertensive patients revealed significantly reduced mortality (OR = 0.69 [95%CI: 0.52–0.91], p = 0.009).ConclusionCCB usage was not associated with the outcome of COVID-19. However, CCB was associated with a decreased mortality rate in hypertensive COVID-19 patients.  相似文献   
103.
ObjectiveTo determine whether a low Braden skin score (BSS), reflecting increased risk for skin pressure injury, would predict lower survival in cardiac intensive care unit (CICU) patients after adjustment for illness severity and comorbidities.Patients and MethodsThis retrospective cohort study included consecutive unique adult patients admitted to a single tertiary care referral hospital CICU from January 1, 2007, through December 31, 2015, who had a BSS documented on CICU admission. The primary outcome was all-cause hospital mortality, using elastic net penalized logistic regression to determine predictors of hospital mortality. The secondary outcome was all-cause post-discharge mortality, using Cox proportional hazards models to determine predictors of post-discharge mortality.ResultsThe study included 9552 patients with a mean age of 67.4±15.2 years (3589 [37.6%] were females) and a hospital mortality rate of 8.3%. Admission BSS was inversely associated with hospital mortality (unadjusted odds ratio, 0.70; 95% CI, 0.68-0.72; P<.001; area under the receiver operator curve, 0.80; 95% CI, 0.78-0.82), with increased short-term mortality as a function of decreasing admission BSS. After adjustment for illness severity and comorbidities using multivariable analysis, admission BSS remained inversely associated with hospital mortality (adjusted odds ratio, 0.88; 95% CI, 0.85-0.92; P<.001). Among hospital survivors, admission BSS was inversely associated with post-discharge mortality after adjustment for illness severity and comorbidities (adjusted hazard ratio, 0.89; 95% CI, 0.88-0. 90; P<.001).ConclusionThe admission BSS, a simple inexpensive bedside nursing assessment potentially reflecting frailty and overall illness acuity, was independently associated with hospital and post-discharge mortality when added to established multiparametric illness severity scores among contemporary CICU patients.  相似文献   
104.
105.

Background

The prognostic role of peripheral lymphocyte subsets in early stage of acute pancreatitis (AP) is unknown.

Methods

After enrollment, blood samples were collected in the first 24 hours of the onset of AP in 164 patients. The lymphocyte count and the percentage of CD3+, CD3+CD4+, CD3+CD8+, CD3?CD19+and CD3?CD (16?+?56)+ cells were assessed.

Results

Reduction of the lymphocyte count and the percentage of CD3+CD8+ and CD3?CD (16?+?56)+ cells within 24 hours of the onset of AP as well as an increase in the percentage of CD3+ and CD3+CD4+ cells were observed. The percentage of CD3?CD (16?+?56)+ cells had the highest accuracy in prediction of AP severity.

Conclusions

Marked changes of the percentages of lymphocyte subset were found in peripheral blood in the early stage of AP. The percentage of CD3?CD (16?+?56)+ cells in peripheral blood could be a potent prognostic predictor.  相似文献   
106.

Background

IgG4 production is regulated by type 2 (IL-4 and IL-13) and regulatory (IL-10) cytokines involved in the pathophysiology of chronic rhinosinusitis (CRS). We sought to determine the pathophysiological characteristics of IgG4-positive cells in sinonasal tissues in CRS, especially eosinophilic CRS (ECRS).

Methods

IgG4-positive cells in uncinate tissues (UT) and nasal polyps (NP) were examined by immunohistochemistry. Associations between the number of IgG4-positive cells and clinicopathological factors were analyzed. Receiver operating characteristics (ROC) analysis was performed to determine the cut-off value of IgG4-positive cells in tissue that can predict the post-operative course.

Results

IgG4 was mainly expressed in infiltrating plasma and plasmacytoid cells, and the number of IgG4-positive cells was significantly higher in NP, especially those from severe ECRS patients, than in UT. In CRS patients, the number of IgG4-positive cells significantly and positively correlated with blood and tissue eosinophilia, radiological severity, and serum level of total IgE. The number of infiltrating IgG4-positive cells was significantly higher in patients with a poor post-operative course (sustained sinus shadow 6 months after surgery) than in those with a good one. The number of IgG4-positive cells in NP could discriminate patients with a good or a poor post-operative course (area under the curve: 0.769). Also, 73.3% sensitivity and 82.5% specificity were achieved when the cut-off value was set at 17 cells/high-power field.

Conclusions

Our results suggest that the local expression of IgG4 on cells may be used as a biomarker that reflects the pathophysiology of CRS, including the post-operative course.  相似文献   
107.
108.
Some have suggested that parents of children with autism spectrum disorder (ASD) may present with less recognizable autistic-like phenotypic characteristics, leading them to highly systemizing occupations. Using secondary analysis of data from two previous studies of children with ASD, we tested associations between parental occupations and ASD diagnosis and the association of parental occupational characteristics on ASD severity. We found that fathers in healthcare (P < 0.01) and finance (P = 0.03) were more likely to have children with ASD. Additionally, joint effects of parental technical occupations were associated with communication (P < 0.01) and social impairment (P = 0.04). These results support that a “broader phenotype” and possible assortative mating in adults with autistic-like characteristics might contribute to intergenerational transmission and having offspring with greater ASD severity.  相似文献   
109.

Objective

To investigate a diagnostic value of ultrasonography in carpal tunnel syndrome (CTS) patients and to evaluate a correlation of sonographic measurements with the degree of electrodiagnostic abnormalities and clinical severity.

Methods

Two-hundred-forty-six symptomatic hands in 135 patients and 30 asymptomatic hands in 19 healthy individuals as control group were included. In ultrasonographic study, we measured the cross-sectional area (CSA) and flattening ratio (FR) of the median nerve at the pisiform as well as palmar bowing (PB) of the flexor retinaculum. Sensitivity and specificity of ultrasonographic measurements were evaluated and ultrasonographic data from the symptomatic and control hands were compared to the grade of electrodiagnostic and clinical severity.

Results

The mean CSA was 13.7±4.2 mm2 in symptomatic hands and 7.9±1.3 mm2 in asymptomatic hands. The mean FR was 4.2±1.0 in symptomatic hands and 3.4±0.4 in asymptomatic hands. The mean PB was 3.5±0.5 mm in symptomatic hands and 2.6±0.3 mm in asymptomatic hands. Statistical analysis showed differences of the mean CSA, FR and PB between groups were significant. A cut-off value of 10 mm2 for the mean CSA was found to be the upper limit for normal value. Both the mean CSA and PB are correlated with the grade of electrophysiological abnormalities and clinical severity, respectively.

Conclusion

Ultrasographic measurement of the CSA and PB is helpful to diagnose CTS as a non-invasive and an alternative modality for the evaluation of CTS. In addition, ultrasonography also provides a reliable correlation with the grade of electrodiagnostic abnormalities and clinical severity.  相似文献   
110.
《Injury》2014,45(11):1693-1699
IntroductionTraffic-related injuries are a major cause of premature death in developing countries. Saudi Arabia has struggled with high rates of traffic-related deaths for decades, yet little is known about health outcomes of motor vehicle victims seeking medical care. This study aims to develop and validate a model to predict in-hospital death among patients admitted to a large-urban trauma centre in Saudi Arabia for treatment following traffic-related crashes.MethodsThe analysis used data from King Abdulaziz Medical City (KAMC) in Riyadh, Saudi Arabia. During the study period 2001–2010, 5325 patients met the inclusion criteria of being injured in traffic crashes and seen in the Emergency Department (ED) and/or admitted to the hospital. Backward stepwise logistic regression, with in-hospital death as the outcome, was performed. Variables with p < 0.05 were included in the final model. The Bayesian Information Criterion (BIC) was employed to identify the most parsimonious model. Model discrimination was evaluated by the C-statistic and calibration by the Hosmer–Lemeshow Goodness of Fit statistic. Bootstrapping was used to assess overestimation of model performance and obtain a corrected C-statistic.Results457 (8.5%) patients died at some time during their treatment in the ED or hospital. Older age, the Triage-Revised Trauma Scale (T-RTS), and Injury Severity Score were independent risk factors for in-hospital death: T-RTS was best modelled with linear and quadratic terms to capture a flattening of the relationship to death in the more severe range. The model showed excellent discrimination (C-statistic = 0.96) and calibration (H–L statistic 4.29 [p > 0.05]). Internal bootstrap validation gave similar results (C-statistic = 0.96).ConclusionsThe proposed model can predict in-hospital death accurately. It can facilitate the triage process among injured patients, and identify unexpected deaths in order to address potential pitfalls in the care process. Conversely, by identifying high-risk patients, strategies can be developed to improve trauma care for these patients and reduce case-fatality. This is the first study to develop and validate a model to predict traffic-related mortality in a developing country. Future studies from developing countries can use this study as a reference for case fatality achievable for different risk profiles at a well-equipped trauma centre.  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