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   501篇
  免费   10篇
耳鼻咽喉   2篇
儿科学   86篇
妇产科学   2篇
基础医学   51篇
口腔科学   15篇
临床医学   15篇
内科学   89篇
皮肤病学   3篇
神经病学   36篇
特种医学   2篇
外科学   20篇
综合类   2篇
预防医学   157篇
眼科学   2篇
药学   14篇
中国医学   2篇
肿瘤学   13篇
  2024年   1篇
  2023年   4篇
  2022年   2篇
  2021年   4篇
  2020年   5篇
  2019年   22篇
  2018年   29篇
  2017年   21篇
  2016年   7篇
  2015年   21篇
  2014年   44篇
  2013年   40篇
  2012年   23篇
  2011年   43篇
  2010年   38篇
  2009年   61篇
  2008年   47篇
  2007年   38篇
  2006年   25篇
  2005年   7篇
  2004年   4篇
  2003年   4篇
  2002年   5篇
  2001年   3篇
  2000年   1篇
  1999年   1篇
  1998年   2篇
  1997年   1篇
  1995年   1篇
  1989年   2篇
  1987年   1篇
  1986年   1篇
  1981年   1篇
  1979年   1篇
  1977年   1篇
排序方式: 共有511条查询结果,搜索用时 11 毫秒
101.
102.
103.
College students have high rates of heavy drinking and other risky behaviors, but little is known about trends in their use of cocaine. In this longitudinal study of 1253 college students at one large, public university in the mid-Atlantic region, annual interviews assessed opportunity to use cocaine, cocaine use, and DSM-IV criteria for cocaine abuse and dependence. Follow-up rates exceeded 87% annually. Data from the first four years of college were analyzed to detect changes over time and possible gender differences. By their fourth year of college, 36%(wt) of students had been offered cocaine at least once in their lifetime, and 13%(wt) had used cocaine. Annual prevalence of cocaine use increased significantly over time (4%(wt) in Year 1 to 10%(wt) in Year 4) and remained similar across genders. Opportunities to use cocaine were significantly more prevalent for males than females during Years 2 through 4. Cocaine use given opportunity increased significantly over time for both males and females. Among 243 cocaine users, females (n=113) had more serious use patterns than males, with higher average frequency of use (18.39 vs. 8.83 days during the peak year of use, p<.05) and greater likelihood of meeting criteria for cocaine dependence (9.3% vs. 2.5%, p<.05). Gender differences in typical cocaine dosage were not apparent. College administrators and health providers should be aware of the prevalence of cocaine use among student populations and design strategies to address the problem.  相似文献   
104.

Background

Preterm children are at risk for executive function (EF) problems, which have been linked to behavior and learning problems in full term children. In this study, we examine the relationship between EF and functional outcomes in preterm children.

Aim

To evaluate (1) EF skills of 9- to 16-year-old children born across the spectrum of gestational age (GA), (2) relationship of degree of prematurity to EF skills, and (3) contributions of EF skills to two functional outcomes — reading scores and parent-rated child function.

Method

Preterm children < 36 weeks gestation (n = 72) were compared to full term children (n = 42) of similar age, gender and SES, on measures of EF, reading, and parent-ratings of child function. Multiple regression models evaluated contributions to EF skills and functional outcomes.

Results

Compared to full term controls, preterm children had poorer EF performance on a complex planning and organization task and did not increase planning time as task difficulty increased. Their spatial memory capacity was not different. GA contributed to EF skills, but was mediated by IQ. EF contributed to the variance in reading skills but did not add to the variance in reading when IQ was considered. EF skills significantly contributed to the variance in parent-rated child function, but IQ did not.

Conclusion

EF skills contribute to measures of functional outcome in this high-risk population. The use of EF skills as an early marker for learning and functional problems and as a target for intervention in children born preterm warrants future study.  相似文献   
105.
Recent work exploring the relationship between socioeconomic status and health has employed a psychosocial concept called perceived social position as a predictor of health. Perceived social position is likely the “cognitive averaging” (Singh-Manoux, Marmot, & Adler, 2005) of socioeconomic characteristics over time and, like other socioeconomic factors, is subject to interplay with health over the life course. Based on the hypothesis that health can also affect perceived social position, in this paper we used structural equation modeling to examine whether perceived social position and three different health outcomes were reciprocally related in the Wisconsin Longitudinal Study, a longitudinal cohort study of older adults in the United States. The relationship between perceived social position and health differed across health outcomes—self-reported health, the Health Utilities Index, and depressive symptoms—as well as across operationalizations of perceived social position—compared to the population of the United States, compared to one's community, and a latent variable of which the two items are indicators. We found that perceived social position affected self-reported health when operationalized as latent and US perceived social position, yet there was a reciprocal relationship between self-reported health and community perceived social position. There was a reciprocal relationship between perceived social position and the Health Utilities Index, and depressive symptoms affected perceived social position for all operationalizations of perceived social position. The findings suggest that the causal relationship hypothesized in prior studies—that perceived social position affects health—does not necessarily hold in empirical models of reciprocal relationships. Future research should interrogate the relationship between perceived social position and health rather than assume the direction of causality in their relationship.  相似文献   
106.
107.
Racial/ethnic disparities in obesity widen dramatically during young adulthood in the US. Understanding racial/ethnic differences in the association between socioeconomic status (SES) and obesity can provide insight on these disparities. However, the delay and complexity of the transition to adulthood create challenges for defining SES using traditional, single indicators, such as income or years of education. Our objective was to define a multidimensional measure of young adult SES using exploratory factor analysis and to investigate whether distinct SES dimensions differentially predicted obesity across race/ethnicity in 11,250 young adults (mean age = 21.9 years) from the National Longitudinal Study of Adolescent Health (Wave III: 2000–2001). Four factors (social advantage; schooling; employment; and economic hardship) extracted from a principal factor analysis on 38 SES indicators comprised our multidimensional measure of young adult SES. The respondents' scores on each factor were entered into gender-stratified Poisson regression models to estimate the relative risk of young adult obesity for a contrast of approximately one standard deviation in score. The association of the “Social advantage” and “Economic hardship” factors with obesity differed by race/ethnicity (p < 0.05 for Wald test of interaction) in females; high “Social advantage” scores were inversely associated with obesity in white and Hispanic females (9–20% lower) while high scores on “Economic hardship” were positively associated with obesity (7–76% higher) in white and Asian females. In contrast, no significant racial/ethnic differences were detected in young adult males. The “Schooling” factor was significantly protective (RR = 0.91; 95% CI: 0.85, 0.98) for females of all racial/ethnic groups. These results facilitate understanding of the impact of multiple, distinct SES dimensions during the complex transition to adulthood and thus provide salient information for reducing racial/ethnic disparities in obesity during this important period for obesity development.  相似文献   
108.
This study examines whether employment disruptions have varying health consequences for White and Black or Hispanic workers in the U.S. Since employment disruptions mark major shocks to socioeconomic status (SES), this analysis also speaks to a broader set of questions about how race/ethnicity and SES shape population-level health disparities. Data from 1999, 2001 and 2003 waves of the U.S. Panel Study of Income Dynamics provide no evidence of racial/ethnic variation in the health consequences of involuntary job loss. However, associations between leaving jobs voluntarily and poor self-assessed health are larger for Black and Hispanic workers than for White workers. This pattern may be linked to downward occupational mobility within the Black and Hispanic sample.  相似文献   
109.

Background

Introduction of new private, voluntary immunizations often results in low vaccine uptake among certain sub-groups within the population. Revealing factors associated with underimmunization is crucial in vaccine endorsement and distribution.

Objective

Our goal was to investigate the effect of child's birth order on private voluntary varicella vaccination.

Methods

A nested case-control study was conducted on a cohort of 110,902 Israeli children under the age of 5 years. We compared social and demographic factors of immunized and unimmunized participants. Logistic regression models were built to examine the association between birth order and vaccination, controlling for child's age, gender, country of birth, ethnicity, parents’ country of birth, area of residence, and socioeconomic status (SES).

Results

Ethnicity had the highest association with varicella immunization status. The odds of vaccination in the general Jewish and Ultra-Orthodox Jewish populations were 25.55- (95%CI:20.13;32.42) and 15.04- (95%CI:10.18;22.22) times the odds in Arab population, respectively. Child's birth order was inversely related to vaccination status and presented a nonlinear exposure-response relationship. This relationship was maintained in different ethnicity and SES groups. Child's birth order was associated with vaccination differently in large (>3 siblings) and small to average-sized sibships (≤3 siblings). Other parameters associated with vaccination were child's and parents’ country of origin, area of residence and SES.

Conclusions

Birth order is an independent risk factor for underimmunization, associated with child's vaccination status beyond economic, social, and demographic parental characteristics.  相似文献   
110.
Disparities in hypertension between African Americans and non-Hispanic whites have been well-documented, yet an explanation for this persistent disparity remains elusive. Since African Americans and non-Hispanic white Americans tend to live in very different social environments, it is not known whether race disparities in hypertension would persist if non-Hispanic whites and African Americans were exposed to similar social environments. We compared data from the Exploring Health Disparities in Integrated Communities-SWB (EHDIC-SWB) Study with the National Health and Nutrition Examination Survey (NHANES) 1999-2004 to determine if race disparities in hypertension in the USA were attenuated in EHDIC-SWB, which is based in a racially integrated community without race differences in income. Hypertension was defined as systolic blood pressure (BP) > or = 140 mmHg (millimeters of mercury) and/or diastolic BP > or = 90 mmHg or respondent's report of taking antihypertensive medications. Of the 1408 study participants, 835 (59.3%) were African American, 628 (44.6%) were men, and the mean age was 40.6 years. After adjustment for potential confounders, various analytic models from EHDIC-SWB and NHANES 1999-2004 data, we found the race odds ratio was between 29.0% and 34% smaller in the EHDIC-SWB sample. We conclude that social and environmental exposures explained a substantial proportion of the race difference in hypertension.  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