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   318篇
  免费   11篇
  国内免费   1篇
儿科学   3篇
妇产科学   9篇
基础医学   17篇
口腔科学   4篇
临床医学   15篇
内科学   207篇
皮肤病学   1篇
神经病学   2篇
特种医学   4篇
外科学   19篇
综合类   8篇
预防医学   12篇
药学   18篇
中国医学   2篇
肿瘤学   9篇
  2023年   1篇
  2022年   2篇
  2021年   9篇
  2020年   2篇
  2019年   15篇
  2018年   9篇
  2017年   6篇
  2016年   8篇
  2015年   6篇
  2014年   18篇
  2013年   12篇
  2012年   32篇
  2011年   25篇
  2010年   19篇
  2009年   10篇
  2008年   27篇
  2007年   28篇
  2006年   28篇
  2005年   27篇
  2004年   16篇
  2003年   10篇
  2002年   3篇
  2001年   4篇
  2000年   5篇
  1999年   3篇
  1994年   1篇
  1988年   1篇
  1980年   1篇
  1973年   2篇
排序方式: 共有330条查询结果,搜索用时 656 毫秒
31.
32.
33.
34.
35.
Loss of major histocompatibility class II (MHC class II) molecules on diffuse large B-cell lymphoma (DLBCL) has been associated with poor survival; however, none of these reports analysed a uniformly treated patient cohort. This study was designed to validate one MHC class II antigen, HLA-DR, as a prognostic marker in patients uniformly treated with the MACOP-B regimen. Immunostaining results were correlated with the international prognostic index (IPI) score and overall survival (OS). Of the 97 cases, 82 had interpretable staining. Of these, 52 expressed HLA-DR (median OS, 16.2 years) while 30 were negative (median OS, 4.2 years, P = 0.037). The IPI was also predictive of OS in the study group (P = 0.023). A Cox multivariate model established both IPI (P = 0.031) and HLA-DR (P = 0.04) as independent predictors of OS. This is the first demonstration of the prognostic relevance of HLA-DR in a uniformly treated DLBCL patient group.  相似文献   
36.
BACKGROUND: Although heart failure disproportionately affects older persons and is associated with significant physical disability, existing data on physical limitations and health-related quality of life (HRQL) derive largely from studies of younger subjects. We compared the relationship between functional limitation and HRQL between older and younger patients with heart failure. METHODS AND RESULTS: We evaluated 546 outpatients with heart failure enrolled in a multicenter prospective cohort study. At baseline and 6 +/- 2 weeks later, functional status was assessed by New York Heart Association (NYHA) classification and 6-minute walk testing. HRQL was measured with the Kansas City Cardiomyopathy Questionnaire (KCCQ). Comparing older (age >65 years, n = 218) and younger patients (n = 328), we assessed baseline HRQL across strata of functional status. In the 484 patients who completed follow-up (194 older and 290 younger patients), we also assessed the changes in HRQL associated with changes in functional status over time. At baseline, older patients had better HRQL than younger patients (mean KCCQ score 60 +/- 25 versus 54 +/- 28, P = .005) in spite of worse NYHA class (mean 2.54 versus 2.35, P < .001) and lower 6-minute walk distances (824 +/- 378 versus 1064 +/- 371 feet, P < .001). After multivariable adjustment including baseline NYHA class, older age was independently correlated with better HRQL (beta = +7.9 points, P < .001). At follow-up, older patients with a deterioration in NYHA class experienced marked declines in HRQL compared with younger patients (mean HRQL change of -14.4 points versus +0.3 points, respectively, P < .001). Analyses using 6-minute walk distance as the functional measure yielded similar results. CONCLUSIONS: Although older patients with heart failure have relatively good HRQL in spite of significant functional limitations, they are at risk for worsening HRQL with further decline in functional status. These results underscore the importance of treatments aimed at maintaining functional status in older persons with heart failure, including those with significant baseline functional limitations.  相似文献   
37.
38.
PURPOSE: Racial differences in the treatment of patients with myocardial infarction are often presented as nationally consistent patterns of care, despite known regional variations in quality of care. We sought to determine whether racial differences in myocardial infarction treatment vary by U.S. census region. METHODS: We conducted a retrospective analysis of medical record data from 138,938 elderly fee-for-service Medicare beneficiaries hospitalized with myocardial infarction between 1994 and 1996. Patients were evaluated for the use (admission, discharge) of aspirin and beta-blockers, and cardiac procedures (cardiac catheterization, any coronary revascularization) within 60 days of admission. RESULTS: Nationally, black patients had lower crude rates of aspirin and beta-blocker use, cardiac catheterization, and coronary revascularization than did white patients. Racial differences in treatment, however, varied by region. Black patients in the Northeast had rates of aspirin use that were similar to those of white patients on admission (50.6% vs. 49.8%, P = 0.58) and at discharge (77.5% vs. 74.2%, P = 0.07), whereas racial differences were observed in the South (admission: 43.7% vs. 48.8%, P <0.001; discharge: 69.5% vs. 73.2%, P <0.001), Midwest (admission: 48.4% vs. 52.3%, P = 0.004), and West (admission: 49.2% vs. 56.2%, P <0.001; discharge: 70.7% vs. 76.2%, P = 0.02). Racial differences in beta-blocker use were comparable across regions (admission: P = 0.59, discharge: P = 0.89). There were no differences in cardiac catheterization use among black and white patients in the Northeast (38.9% vs. 40.5%, P = 0.24), as opposed to the Midwest (43.3% vs. 48.9%, P <0.001), South (39.2% vs. 48.5%, P <0.001), and West (38.3% vs. 48.6%, P <0.001). Similarly, racial differences in any coronary revascularization use were smallest in the Northeast (22.1% vs. 26.7%, P <0.001), greater in the Midwest (24.7% vs. 33.5%, P <0.001), and largest in the South (20.7% vs. 32.0%, P <0.001) and West (22.9% vs. 33.7%, P <0.001). Regional variations in racial differences persisted after multivariable adjustment for aspirin on admission (P = 0.09) and any coronary revascularization (P = 0.10). CONCLUSION: Racial differences in the use of some therapies for myocardial infarction in patients hospitalized between 1994 and 1996 varied by region, suggesting that national evaluations of racial differences in health care use may obscure potentially important regional variations.  相似文献   
39.

Background

Left ventricular hypertrophy is a major independent risk factor for cardiovascular mortality. The contribution of left ventricular hypertrophy to racial and ethnic differences in cardiovascular mortality is poorly understood.

Methods

We used data from the Third National Health and Nutrition Examination Survey and from the National Death Index to compare mortality for those with an electrocardiographic (ECG) diagnosis of left ventricular hypertrophy to those without left ventricular hypertrophy separately for whites, African Americans, and Latinos. We used Cox proportional hazards regression to control for other known prognostic factors.

Results

ECG left ventricular hypertrophy was significantly associated with 10-year cardiovascular mortality in all 3 racial/ethnic groups, both unadjusted and adjusted for other known prognostic factors. The hazard ratio for this association was significantly greater for African Americans (2.31; 95% confidence interval [CI], 1.55-3.42) than for whites and Latinos (1.32; 95% CI, 1.14-1.76 and 2.11; 95% CI, 1.35-3.30, respectively), independent of systolic blood pressure.

Conclusions

ECG left ventricular hypertrophy contributes more to the risk of cardiovascular mortality in African Americans than it does in whites. Using regression of ECG left ventricular hypertrophy as a goal of therapy might be a means to reduce racial differences in cardiovascular mortality; prospective validation is required.  相似文献   
40.
BACKGROUND: Although B-type natriuretic peptide (BNP) levels have been proposed as a means of assessing disease severity in patients with heart failure, it is not known if BNP levels are correlated with health status (symptom burden, functional limitation, and quality of life). METHODS AND RESULTS: We studied 342 outpatients with systolic heart failure from 14 centers at baseline and 6 +/- 2 weeks with BNP levels and the Kansas City Cardiomyopathy Questionnaire (KCCQ), a heart-failure-specific health status instrument. We assessed the correlation between KCCQ scores and BNP at baseline and changes in KCCQ according to changes in BNP levels between baseline and follow-up. Mean baseline BNP levels were 379 +/- 387 pg/mL and mean KCCQ summary scores were 62 +/- 23 points. Although baseline BNP and KCCQ were both associated with New York Heart Association classification (P < .001 for both), BNP and KCCQ were not correlated (r(2) = 0.008, P = .15). There was no significant relationship between changes in BNP and KCCQ regardless of the threshold used to define a clinically meaningful BNP change. For example, using >50% BNP change threshold, KCCQ improved by 3.7 +/- 14.2 in patients with decreasing BNP, improved by 1.7 +/- 13.6 in patients with no BNP change, and improved by 1.0 +/- 13.4 in patients with increasing BNP (P = .6). CONCLUSION: BNP and health status are not correlated in outpatients with heart failure in the short term. This suggests that these measures may assess different aspects of heart failure severity, and that physiologic measures do not reflect patients' perceptions of the impact of heart failure on their health status.  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