全文获取类型
| 收费全文 | 309741篇 |
| 免费 | 42394篇 |
| 国内免费 | 3910篇 |
专业分类
| 耳鼻咽喉 | 7187篇 |
| 儿科学 | 8327篇 |
| 妇产科学 | 6121篇 |
| 基础医学 | 27387篇 |
| 口腔科学 | 4902篇 |
| 临床医学 | 41654篇 |
| 内科学 | 77049篇 |
| 皮肤病学 | 11542篇 |
| 神经病学 | 26564篇 |
| 特种医学 | 14351篇 |
| 外国民族医学 | 2篇 |
| 外科学 | 61825篇 |
| 综合类 | 3399篇 |
| 现状与发展 | 78篇 |
| 一般理论 | 82篇 |
| 预防医学 | 16846篇 |
| 眼科学 | 7622篇 |
| 药学 | 15106篇 |
| 4篇 | |
| 中国医学 | 2037篇 |
| 肿瘤学 | 23960篇 |
出版年
| 2023年 | 5453篇 |
| 2022年 | 3419篇 |
| 2021年 | 8103篇 |
| 2020年 | 8456篇 |
| 2019年 | 5854篇 |
| 2018年 | 11682篇 |
| 2017年 | 10506篇 |
| 2016年 | 12362篇 |
| 2015年 | 13956篇 |
| 2014年 | 22145篇 |
| 2013年 | 23703篇 |
| 2012年 | 18174篇 |
| 2011年 | 17813篇 |
| 2010年 | 17433篇 |
| 2009年 | 20052篇 |
| 2008年 | 15078篇 |
| 2007年 | 13235篇 |
| 2006年 | 14904篇 |
| 2005年 | 11797篇 |
| 2004年 | 10243篇 |
| 2003年 | 8332篇 |
| 2002年 | 7541篇 |
| 2001年 | 8281篇 |
| 2000年 | 7094篇 |
| 1999年 | 6508篇 |
| 1998年 | 4933篇 |
| 1997年 | 4459篇 |
| 1996年 | 4305篇 |
| 1995年 | 4056篇 |
| 1994年 | 2705篇 |
| 1993年 | 2210篇 |
| 1992年 | 2947篇 |
| 1991年 | 2976篇 |
| 1990年 | 2418篇 |
| 1989年 | 2414篇 |
| 1988年 | 2169篇 |
| 1987年 | 1876篇 |
| 1986年 | 1895篇 |
| 1985年 | 1595篇 |
| 1984年 | 1190篇 |
| 1983年 | 1083篇 |
| 1982年 | 907篇 |
| 1981年 | 777篇 |
| 1980年 | 693篇 |
| 1979年 | 824篇 |
| 1978年 | 730篇 |
| 1977年 | 782篇 |
| 1975年 | 578篇 |
| 1974年 | 578篇 |
| 1972年 | 615篇 |
排序方式： 共有10000条查询结果，搜索用时 453 毫秒
91.
Marginal rate-based analyses are widely used for the analysis of recurrent events in clinical trials. In many areas of application, the events are not instantaneous but rather signal the onset of a symptomatic episode representing a recurrent infection, respiratory exacerbation, or bout of acute depression. In rate-based analyses, it is unclear how to best handle the time during which individuals are experiencing symptoms and hence are not at risk. We derive the limiting value of the Nelson-Aalen estimator and estimators of the regression coefficients under a semiparametric rate-based model in terms of an underlying two-state process. We investigate the impact of the distribution of the episode durations, heterogeneity, and dependence on the asymptotic and finite sample properties of standard estimators. We also consider the impact of these features on power in trials designed to test intervention effects on rate functions. An application to a trial of individuals with herpes simplex virus is given for illustration. 相似文献
92.
93.
Marie V. Plaisime PhD MPH Marie Jipguep-Akhtar PhD Joseph J. Locascio PhD Harolyn M. E. Belcher MD MHS Rachel R. Hardeman PhD MPH Katherine Picho-Kiroga PhD Sylvia P. Perry PhD Sean M. Phelan PhD MPH Michelle van Ryn PhD LMFT MPH John F. Dovidio PhD 《Health services research》2023,58(Z2):229-237
Objective
To examine the experience of interracial anxiety among health professionals and how it may affect the quality of their interactions with patients from racially marginalized populations. We explored the influence of prior interracial exposure—specifically through childhood neighborhoods, college student bodies, and friend groups—on interracial anxiety among medical students and residents. We also examined whether levels of interracial anxiety change from medical school through residency.Data Source
Web-based longitudinal survey data from the Medical Student Cognitive Habits and Growth Evaluation Study.Study Design
We used a retrospective longitudinal design with four observations for each trainee. The study population consisted of non-Black US medical trainees surveyed in their 1st and 4th years of medical school and 2nd and 3rd years of residency. Mixed effects longitudinal models were used to assess predictors of interracial anxiety and assess changes in interracial anxiety scores over time.Principal Findings
In total, 3155 non-Black medical trainees were followed for 7 years. Seventy-eight percent grew up in predominantly White neighborhoods. Living in predominantly White neighborhoods and having less racially diverse friends were associated with higher levels of interracial anxiety among medical trainees. Trainees' interracial anxiety scores did not substantially change over time; interracial anxiety was highest in the 1st year of medical school, lowest in the 4th year, and increased slightly during residency.Conclusions
Neighborhood and friend group composition had independent effects on interracial anxiety, indicating that premedical racial socialization may affect medical trainees' preparedness to interact effectively with diverse patient populations. Additionally, the lack of substantial change in interracial anxiety throughout medical training suggests the importance of providing curricular tools and structure (e.g., instituting interracial cooperative learning activities) to foster the development of healthy interracial relationships. 相似文献94.
Denise Lee Marcella D. Walker Hsin Yi Chen John A. Chabot James A. Lee Jennifer H. Kuo 《Surgery》2019,165(1):107-113
Background
Bone mineral density (BMD) has been found to improve after parathyroidectomy (PTX) in patients with primary hyperparathyroidism. There are few data on the effect of PTX on BMD in normocalcemic and normohormonal primary hyperparathyroidism.Methods
A retrospective analysis of 92 primary hyperparathyroidism patients who underwent PTX between 2004 and 2012 with pre- and post-PTX dual-energy x-ray absorptiometry was performed. Within-person changes in BMD pre- and post-PTX were analyzed using log linear mixed models, stratified by biochemical status.Results
Bone mineral density increased post-PTX in the whole cohort at the lumbar spine (+2.5%), femoral neck (+2.1%), and total hip (+1.9%) and decreased at the one-third radius (–0.9%). On comparison of BMD changes by profile, BMD increased in those with the typical profile at the lumbar spine (3.2%), femoral neck (2.9%), and total hip (2.9%) but declined at the one-third radius (–1.5%). In contrast, BMD improved only at the femoral neck (4.3%) in the normohormonal group and did not change at any site in the normocalcemic group. The typical group had a greater increase in BMD over time at the femoral neck and total hip compared with normocalcemic patients.Conclusion
Our results indicate that the skeletal benefit of PTX was attenuated in normocalcemic and normohormonal patients, suggesting that skeletal changes after PTX may depend on biochemical profile. 相似文献95.
96.
Chien-Hua Tseng Ben-Jei Tsuang Chun-Ju Chiang Kai-Chen Ku Jeng-Sen Tseng Tsung-Ying Yang Kuo-Hsuan Hsu Kun-Chieh Chen Sung-Liang Yu Wen-Chung Lee Tsang-Wu Liu Chang-Chuan Chan Gee-Chen Chang 《Journal of thoracic oncology》2019,14(5):784-792
Introduction
For never-smokers (smoked <100 lifetime cigarettes), lung cancer (LC) has emerged as an important issue. We aimed to investigate the effects of prevalence changes in tobacco smoking and particulate matter (PM) 2.5 (PM2.5) levels on LC in Taiwan, in relation to contrasting PM2.5 levels, between Northern Taiwan (NT) and Southern Taiwan (ST).Methods
We reviewed 371,084 patients with LC to assess smoking prevalence and correlations between the incidence of adenocarcinoma lung cancer (AdLC) and non-AdLC. Two subsets were selected to assess different AdLC stage trends and the effect of PM2.5 on survival of patients with AdLC.Results
From 1995 to 2015, the proportion of male adult ever-smokers decreased from 59.4% to 29.9% whereas the female smoking rate remained low (3.2% to 5.3%). AdLC incidence in males and females increased from 9.06 to 23.25 and 7.05 to 24.22 per 100,000 population, respectively. Since 1993, atmospheric visibility in NT improved (from 7.6 to 11.5 km), but deteriorated in ST (from 16.3 to 4.2 km). The annual percent change in AdLC stages IB to IV was 0.3% since 2009 (95% confidence interval [CI]: -1.9%–2.6%) in NT, and 4.6% since 2007 (95% CI: 3.3%–5.8%) in ST; 53% patients with LC had never smoked. Five-year survival rates for never-smokers, those with EGFR wild-type genes, and female patients with AdLC were 12.6% in NT and 4.5% in ST (hazard ratio: 0.79, 95% CI: 0.70–0.90).Conclusions
In Taiwan, greater than 50% of patients with LC had never smoked. PM2.5 level changes can affect AdLC incidence and patient survival. 相似文献97.
98.
99.
Yinong Young-Xu Julia Thornton Snider Robertus van Aalst Salaheddin M. Mahmud Edward W. Thommes Jason K.H. Lee David P. Greenberg Ayman Chit 《Vaccine》2019,37(11):1484-1490
Background
Observational studies of the relative effectiveness of influenza vaccines are essential for public health decision making. Their estimates, however, are subject to bias due to unmeasured confounders. Instrumental variable (IV) methods can control for observed and unobserved confounders.Methods
We used linked electronic medical record databases in the Veterans Health Administration (VHA) as well as Medicare administrative files to examine the relative vaccine effectiveness (rVE) of high-dose influenza vaccine (HD) versus standard-dose influenza vaccines (SD) in preventing hospitalizations among VHA-enrolled Veterans ≥65?years of age during 5 influenza seasons (2010–2011 through 2014–2015). Using multivariable IV Poisson regression modeling to address unmeasured confounding and bias, we analyzed the data by each season and through longitudinal analysis of all five seasons.Findings
We included 3,638,924 person–influenza seasons of observation where 158,636 (4%) were among HD vaccine recipients and 3,480,288 (96%) were among SD vaccine recipients. Of the 1,728,562 Veterans, 1,702,824 (98.5%) were male and 1,299,412 (75%) were non-Hispanic white. Based on the longitudinal analysis of all five seasons, the IV-adjusted rVE estimate of HD vs. SD was 10% (95% CI, 8–12%) against all-cause hospitalization; 18% (95% CI, 15–21%) against cardiorespiratory-associated hospitalization; and 14% (95% CI, 6–22%) against influenza/pneumonia-associated hospitalization. The findings by season were similar.Interpretation
Our analysis of VHA clinical data collected from approximately 1.7 million Veterans 65?years and older during five seasons demonstrates that high-dose influenza vaccine is more effective than standard-dose influenza vaccines in preventing influenza- or pneumonia-associated hospitalizations, cardiorespiratory hospitalizations, and all-cause hospitalizations. 相似文献100.
Stress Testing Versus CT Angiography in Patients With Diabetes and Suspected Coronary Artery Disease
Abhinav Sharma Adrian Coles Nishant K. Sekaran Neha J. Pagidipati Michael T. Lu Daniel B. Mark Kerry L. Lee Hussein R. Al-Khalidi Udo Hoffmann Pamela S. Douglas 《Journal of the American College of Cardiology》2019,73(8):893-902