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   733025篇
  免费   53765篇
  国内免费   4057篇
耳鼻咽喉   5670篇
儿科学   26972篇
妇产科学   25285篇
基础医学   78207篇
口腔科学   23009篇
临床医学   80879篇
内科学   121234篇
皮肤病学   10898篇
神经病学   66466篇
特种医学   27405篇
外国民族医学   9篇
外科学   89223篇
综合类   18365篇
现状与发展   40篇
一般理论   291篇
预防医学   120049篇
眼科学   9619篇
药学   42586篇
  166篇
中国医学   2058篇
肿瘤学   42416篇
  2024年   804篇
  2023年   23774篇
  2022年   31989篇
  2021年   40777篇
  2020年   40143篇
  2019年   27925篇
  2018年   32539篇
  2017年   32367篇
  2016年   30823篇
  2015年   30284篇
  2014年   51913篇
  2013年   48407篇
  2012年   36664篇
  2011年   35380篇
  2010年   35372篇
  2009年   32330篇
  2008年   25179篇
  2007年   25108篇
  2006年   22011篇
  2005年   19340篇
  2004年   17154篇
  2003年   16334篇
  2002年   15580篇
  2001年   14425篇
  2000年   13226篇
  1999年   12458篇
  1998年   6792篇
  1997年   5721篇
  1996年   5775篇
  1995年   4936篇
  1994年   4030篇
  1993年   3323篇
  1992年   6341篇
  1991年   6022篇
  1990年   5763篇
  1989年   4882篇
  1988年   5033篇
  1987年   2252篇
  1986年   967篇
  1985年   1661篇
  1984年   1811篇
  1983年   1455篇
  1982年   1461篇
  1981年   1240篇
  1980年   1125篇
  1979年   1016篇
  1978年   904篇
  1977年   727篇
  1976年   690篇
  1974年   587篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.

Objective

The aim of the study was to estimate the effect of the state-based reinsurance programs through the section 1332 State Innovation Waivers on health insurance marketplace premiums and insurer participation.

Data Source

2015 to 2022 Robert Wood Johnson Foundation Health Insurance Exchange Compare Datasets.

Study Design

An event study difference-in-differences (DD) model separately for each year of implementation and a synthetic control method (SCM) are used to estimate year-by-year effects following program implementation.

Data Collection/Extraction Methods

Not applicable.

Principal Findings

Reinsurance programs were associated with a decline in premiums in the first year of implementation by 10%–13%, 5%–19%, and 11%–17% for bronze, silver, and gold plans (p < 0.05). There is a trend of sustained declines especially for states that implemented their programs in 2019 and 2020. The SCM analyses suggest some effect heterogeneity across states but also premium declines across most states. There is no evidence that reinsurance programs affected insurer participation.

Conclusion

State-based reinsurance programs have the potential to improve the affordability of health insurance coverage. However, reinsurance programs do not appear to have had an effect on insurer participation, highlighting the need for policy makers to consider complementary strategies to encourage insurer participation.  相似文献   
2.
3.
4.
5.
BackgroundVoices for Food was a longitudinal community, food pantry–based intervention informed by the social ecological model, and designed to improve food security, dietary intake, and quality among clients, which was carried out in 24 rural food pantries across 6 Midwestern states.ObjectiveOur objective was to evaluate changes in adult food security, dietary intake, and quality from baseline (2014) to follow-up (2016), and to assess the role of adult food security on dietary outcomes.DesignA multistate, longitudinal, quasi-experimental intervention with matched treatment and comparison design was used to evaluate treatment vs comparison group changes over time and changes in both groups over time.Participants/settingAdult food pantry clients (n = 617) completed a demographic food security survey, and up to three 24-hour dietary recalls at baseline (n = 590) and follow-up (n = 160).InterventionCommunity coaching served as the experimental component, which only “treatment” communities received, and a food council guide and food pantry toolkit were provided to both “treatment” and matched “comparison” communities.Main outcome measuresChange in adult food security status, mean usual intakes of nutrients and food groups, and Healthy Eating Index-2010 scores were the main outcome measures.Statistical analyses performedLinear mixed models estimated changes in outcomes by intervention group and by adult food security status over time.ResultsImprovements in adult food security score (–0.7 ± 0.3; P = .01), Healthy Eating Index-2010 total score (4.2 ± 1.1; P < .0001), and empty calories component score (3.4 ± 0.5; P <.0001) from baseline to follow-up were observed in treatment and comparison groups, but no statistically significant changes were found for adult food security status, dietary quality, and usual intakes of nutrients and food groups between the 2 groups over time. The intervention effect on dietary quality and usual intake changes over time by adult food security status were also not observed.ConclusionsFood pantry clients in treatment and comparison groups had higher food security and dietary quality at the follow-up evaluation of the Voices for Food intervention trial compared with baseline, despite the lack of difference among the groups as a result of the experimental coaching component.  相似文献   
6.
The purpose of this study was to investigate the association between habitual snoring (HS), middle ear disease (MED), and speech problems in children with cleft palate. This cross-sectional study included children aged 2.0–7.9 years with non-syndromic cleft palate anomalies. Parents completed the Pediatric Sleep Questionnaire and a questionnaire about MED. Audiograms and speech assessment were also conducted. Ninety-five children were enrolled; 15.2% of families reported HS, 97.6% MED, and 17.1% speech problems. HS (37.5% vs 10.3%, P = 0.007) and early episodes of MED (92.3% vs 58.2%, P = 0.021) were more likely to be reported for children with isolated cleft palate when compared to those with cleft lip and palate. Children with cleft lip and palate had a higher frequency of MED with effusion compared to those with Robin sequence (86.4% vs 57.1%, P = 0.049). The odds ratio for HS in children with ≥1 episode of MED in the last year was 7.37 (95% confidence interval 1.55–35.15, P = 0.012). There was a trend for children with speech problems reported by parents to have HS (30.8% vs 11.5%, P= 0.076). Anatomical factors play a role in the frequency of upper airway symptoms in children with cleft palate. A recent history of at least one episode of MED was associated with an increased frequency of HS.  相似文献   
7.
AimInpatient dysglycemia has been linked to short-term mortality, but longer-term mortality data are lacking. Our aim was to evaluate the association between inpatient dysglycemia and one-year mortality risk.MethodsRetrospective chart review of adults with diabetes hospitalized between 2015 and 2019. The Charlson Comorbidity Index (CCI) was used to estimate 1-year mortality risk, stratified into low (CCI ≤ 5) and high risk (CCI ≥6). Simple and multivariable logistic regression was used to evaluate the association between dysglycemic measures and high mortality risk.ResultsAmong 22,639 unique admissions, BG ≥ 180, ≥300, ≤70, <54 and <40 mg/dL were associated with adjusted odds of 1.43 (95 % CI, 1.33, 1.54), 1.58 (95 % CI, 1.48, 1.68), 2.16 (95 % CI, 2.01, 2.32), 2.58 (95 % CI, 2.32, 2.86), and 2.56 (95 % CI, 2.19, 2.99) for high mortality risk, respectively. Older age and Black race were positively associated with hyperglycemia and hypoglycemia. Myocardial infarction, congestive heart failure (CHF), and moderate to severe liver disease were most strongly associated with hyperglycemia, while renal disease, CHF, peripheral vascular disease, and peptic ulcer disease were most strongly associated with hypoglycemia.ConclusionsInpatient hypoglycemia and hyperglycemia were both positively associated with higher one-year mortality risk, with stronger magnitude of association observed for hypoglycemia. The association appears to be mediated mainly by presence of diabetes-related complications.  相似文献   
8.
9.
10.
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