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   4473139篇
  免费   365331篇
  国内免费   15474篇
耳鼻咽喉   62933篇
儿科学   143189篇
妇产科学   116641篇
基础医学   677590篇
口腔科学   120626篇
临床医学   414939篇
内科学   817771篇
皮肤病学   112887篇
神经病学   381740篇
特种医学   174039篇
外国民族医学   764篇
外科学   682193篇
综合类   122446篇
现状与发展   93篇
一般理论   2711篇
预防医学   366434篇
眼科学   104992篇
药学   313448篇
  23篇
中国医学   12071篇
肿瘤学   226414篇
  2021年   57732篇
  2020年   38479篇
  2019年   59894篇
  2018年   78152篇
  2017年   60295篇
  2016年   66834篇
  2015年   79605篇
  2014年   116714篇
  2013年   182554篇
  2012年   132771篇
  2011年   138544篇
  2010年   132434篇
  2009年   134739篇
  2008年   124654篇
  2007年   132157篇
  2006年   141187篇
  2005年   134746篇
  2004年   135394篇
  2003年   125123篇
  2002年   114057篇
  2001年   168459篇
  2000年   163105篇
  1999年   149869篇
  1998年   73417篇
  1997年   69030篇
  1996年   66675篇
  1995年   61965篇
  1994年   55649篇
  1993年   51492篇
  1992年   107063篇
  1991年   101907篇
  1990年   97651篇
  1989年   95268篇
  1988年   87516篇
  1987年   85633篇
  1986年   80542篇
  1985年   78655篇
  1984年   65644篇
  1983年   58413篇
  1982年   47425篇
  1981年   44049篇
  1980年   41246篇
  1979年   55234篇
  1978年   44877篇
  1977年   40095篇
  1976年   36945篇
  1975年   36894篇
  1974年   39715篇
  1973年   37839篇
  1972年   35440篇
排序方式: 共有10000条查询结果,搜索用时 15 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.
Quality of Life Research - The COVID-19 pandemic might add to the stressors experienced by people living with rheumatic diseases. This study aimed to examine rheumatic patients’ functional...  相似文献   
4.
Molnár  B.  Aroca  S.  Dobos  A.  Orbán  K.  Szabó  J.  Windisch  P.  Stähli  A.  Sculean  A. 《Clinical oral investigations》2022,26(12):7135-7142
Clinical Oral Investigations - To evaluate t he long-term outcomes following treatment of RT 1 multiple adjacent gingival recessions (MAGR) using the modified coronally advanced tunnel (MCAT) with...  相似文献   
5.

Physical activity brings significant health benefits to middle-aged adults, although the research to date has been focused on late adulthood. This study aims to examine how ageing affects the self-reported and accelerometer-derived measures of physical activity levels in middle-aged adults. We employed the data recorded in the UK Biobank and analysed the physical activity levels of 2,998 participants (1381 men and 1617 women), based on self-completion questionnaire and accelerometry measurement of physical activity. We also assessed the musculoskeletal health of the participants using the dual-energy X-ray absorptiometry (DXA) measurements provided by the UK Biobank. Participants were categorised into three groups according to their age: group I younger middle-aged (40 to 49 years), group II older middle-aged (50 to 59 years), and group III oldest middle-aged (60 to 69 years). Self-reported physical activity level increased with age and was the highest in group III, followed by group II and I (P?<?0.05). On the contrary, physical activity measured by accelerometry decreased significantly with age from group I to III (P?<?0.05), and the same pertained to the measurements of musculoskeletal health (P?<?0.05). It was also shown that middle-aged adults mostly engaged in low and moderate intensity activities. The opposing trends of the self-reported and measured physical activity levels may suggest that middle-aged adults over-report their activity level as they age. They should be aware of the difference between their perceived and actual physical activity levels, and objective measures would be useful to prevent the decline in musculoskeletal health.

  相似文献   
6.
7.

Interstitial lung disease (ILD) represents a significant cause of morbidity and mortality in systemic sclerosis (SSc). The purpose of this study was to examine recirculating lymphocytes from SSc patients for potential biomarkers of interstitial lung disease (ILD). Peripheral blood mononuclear cells (PBMCs) were isolated from patients with SSc and healthy controls enrolled in the Vanderbilt University Myositis and Scleroderma Treatment Initiative Center cohort between 9/2017–6/2019. Clinical phenotyping was performed by chart abstraction. Immunophenotyping was performed using both mass cytometry and fluorescence cytometry combined with t-distributed stochastic neighbor embedding analysis and traditional biaxial gating. This study included 34 patients with SSc-ILD, 14 patients without SSc-ILD, and 25 healthy controls. CD21lo/neg cells are significantly increased in SSc-ILD but not in SSc without ILD (15.4 ± 13.3% vs. 5.8 ± 0.9%, p = 0.002) or healthy controls (5.0 ± 0.5%, p < 0.0001). While CD21lo/neg B cells can be identified from a single biaxial gate, tSNE analysis reveals that the biaxial gate is comprised of multiple distinct subsets, all of which are increased in SSc-ILD. CD21lo/neg cells in both healthy controls and SSc-ILD are predominantly tBET positive and do not have intracellular CD21. Immunohistochemistry staining demonstrated that CD21lo/neg B cells diffusely infiltrate the lung parenchyma of an SSc-ILD patient. Additional work is needed to validate this biomarker in larger cohorts and longitudinal studies and to understand the role of these cells in SSc-ILD.

  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