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   2683290篇
  免费   241835篇
  国内免费   12621篇
耳鼻咽喉   37291篇
儿科学   85780篇
妇产科学   68567篇
基础医学   449052篇
口腔科学   71536篇
临床医学   239095篇
内科学   453151篇
皮肤病学   78715篇
神经病学   235910篇
特种医学   106860篇
外国民族医学   68篇
外科学   428340篇
综合类   86795篇
现状与发展   23篇
一般理论   2122篇
预防医学   225868篇
眼科学   60795篇
药学   180674篇
  17篇
中国医学   8312篇
肿瘤学   118775篇
  2021年   54183篇
  2020年   34698篇
  2019年   57563篇
  2018年   69501篇
  2017年   52465篇
  2016年   57832篇
  2015年   72423篇
  2014年   106545篇
  2013年   171545篇
  2012年   71794篇
  2011年   68798篇
  2010年   111182篇
  2009年   117116篇
  2008年   56264篇
  2007年   56713篇
  2006年   68397篇
  2005年   64118篇
  2004年   66550篇
  2003年   57911篇
  2002年   47916篇
  2001年   64032篇
  2000年   55416篇
  1999年   63444篇
  1998年   60764篇
  1997年   59738篇
  1996年   57393篇
  1995年   52921篇
  1994年   47081篇
  1993年   43689篇
  1992年   41056篇
  1991年   39237篇
  1990年   36483篇
  1989年   36760篇
  1988年   34126篇
  1987年   33277篇
  1986年   31709篇
  1985年   32913篇
  1984年   34055篇
  1983年   32333篇
  1982年   36347篇
  1981年   34676篇
  1980年   32726篇
  1979年   26291篇
  1978年   26440篇
  1977年   24943篇
  1976年   22680篇
  1975年   20699篇
  1974年   19780篇
  1973年   19110篇
  1972年   18051篇
排序方式: 共有10000条查询结果,搜索用时 156 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.
【摘要】 目的 探讨经动脉栓塞术(transarterial embolization,TAE)治疗食管癌出血的有效性及安全性。方法 收集2018年1月至2020年12月行TAE治疗的14例食管癌出血患者的临床资料、技术成功率、临床成功率,严重并发症情况。评估TAE治疗的有效性及安全性。结果 14例患者中导管成功选择性插入靶动脉并行栓塞患者11例。9例患者接受治疗后未再出现出血征象。出血的主要责任血管为胃左动脉7例,支气管动脉6例和食管固有动脉6例。栓塞材料为微弹簧圈、明胶海绵颗粒及聚乙烯醇颗粒。常见不良反应有疼痛、发热,其中1例患者发生食管瘘。结论 对于内科治疗无效的食管癌出血,TAE可以起到良好的疗效。食管瘘作为术后的严重并发症,需特别注意预防。对于胸段食管癌及食管胃交界处癌,最常见的责任血管为胃左动脉、支气管动脉及食管固有动脉。  相似文献   
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