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   10101244篇
  免费   647633篇
  国内免费   159341篇
耳鼻咽喉   130884篇
儿科学   282743篇
妇产科学   232026篇
基础医学   1255404篇
口腔科学   264738篇
临床医学   1023677篇
内科学   1699374篇
皮肤病学   203896篇
神经病学   731534篇
特种医学   377487篇
外国民族医学   1678篇
外科学   1332376篇
综合类   706550篇
现状与发展   513篇
一般理论   3789篇
预防医学   810017篇
眼科学   230908篇
药学   864326篇
  2771篇
中国医学   209522篇
肿瘤学   544005篇
  2022年   130657篇
  2021年   199411篇
  2020年   141862篇
  2019年   146135篇
  2018年   178302篇
  2017年   158600篇
  2016年   152652篇
  2015年   189496篇
  2014年   277563篇
  2013年   369548篇
  2012年   522438篇
  2011年   566711篇
  2010年   383870篇
  2009年   344989篇
  2008年   482427篇
  2007年   502973篇
  2006年   480256篇
  2005年   442344篇
  2004年   389248篇
  2003年   360831篇
  2002年   332503篇
  2001年   312336篇
  2000年   310926篇
  1999年   266410篇
  1998年   111198篇
  1997年   97711篇
  1996年   91807篇
  1995年   83908篇
  1994年   76064篇
  1993年   65030篇
  1992年   183025篇
  1991年   177067篇
  1990年   171755篇
  1989年   166708篇
  1988年   154119篇
  1987年   150058篇
  1986年   142937篇
  1985年   136278篇
  1984年   103807篇
  1983年   89147篇
  1982年   56857篇
  1979年   93178篇
  1978年   66882篇
  1977年   57685篇
  1976年   53470篇
  1975年   58516篇
  1974年   67517篇
  1973年   64422篇
  1972年   59541篇
  1971年   55152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.
目的 系统评价翻转课堂教学模式在物理治疗学教学中的应用效果。方法 计算机检索CENTRAL、MEDLINE、EMBASE、CINAHL Plus、Academic Search Premier、Teacher Reference Center、ERIC以及Education Research,纳入翻转课堂教学模式应用于物理治疗学教学的原始研究。检索时限为建库至2021年6月。由2名研究人员独立完成文献筛选、数据提取、质量评价,对翻转课堂教学模式对比传统教学模式在物理治疗学教学中的效果进行综述。结果与结论 共检索文献1 307篇,最终纳入7篇,包括至少770名学生。发表时间集中在2013年至2019年,研究对象为物理治疗学专业学生,主要结局指标为考试成绩。翻转课堂教学模式总体说来可提高学生的笔试成绩,增强高阶思维能力,得到了学生和教师的积极评价。  相似文献   
4.
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   
5.
Cao  Jie  Xie  Chengyu  Hou  Zhiru 《Ecotoxicology (London, England)》2022,31(2):259-270
Ecotoxicology - Soil heavy metal pollution evaluations are a necessary measure for mine ecological control projects. In this study, the heavy metals Pb, Zn and Cd were studied in mining areas,...  相似文献   
6.
Kinase alterations are increasingly recognised as oncogenic drivers in mesenchymal tumours. Infantile fibrosarcoma and the related renal tumour, congenital mesoblastic nephroma, were among the first solid tumours shown to harbour recurrent tyrosine kinase fusions, with the canonical ETV6::NTRK3 fusion identified more than 20 years ago. Although targeted testing has long been used in diagnosis, the advent of more robust sequencing techniques has driven the discovery of kinase alterations in an array of mesenchymal tumours. As our ability to identify these genetic alterations has improved, as has our recognition and understanding of the tumours that harbour these alterations. Specifically, this study will focus upon mesenchymal tumours harbouring NTRK or other kinase alterations, including tumours with an infantile fibrosarcoma-like appearance, spindle cell tumours resembling lipofibromatosis or peripheral nerve sheath tumours and those occurring in adults with a fibrosarcoma-like appearance. As publications describing the histology of these tumours increase so, too, do the variety kinase alterations reported, now including NTRK1/2/3, RET, MET, RAF1, BRAF, ALK, EGFR and ABL1 fusions or alterations. To date, these tumours appear locally aggressive and rarely metastatic, without a clear link between traditional features used in histological grading (e.g. mitotic activity, necrosis) and outcome. However, most of these tumours are amenable to new targeted therapies, making their recognition of both diagnostic and therapeutic import. The goal of this study is to review the clinicopathological features of tumours with NTRK and other tyrosine kinase alterations, discuss the most common differential diagnoses and provide recommendations for molecular confirmation with associated treatment implications.  相似文献   
7.
8.
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   
9.
European Surgery - Large skin defects caused by trauma (e.g., burns) or due to other reasons (e.g., tumor-related skin resections) require sufficient skin replacement. The constant improvement of...  相似文献   
10.

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   
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