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   104198篇
  免费   31076篇
  国内免费   1516篇
耳鼻咽喉   2485篇
儿科学   2695篇
妇产科学   2411篇
基础医学   3539篇
口腔科学   5123篇
临床医学   26878篇
内科学   25254篇
皮肤病学   3622篇
神经病学   12303篇
特种医学   4054篇
外国民族医学   8篇
外科学   18286篇
综合类   1440篇
现状与发展   41篇
一般理论   4篇
预防医学   13696篇
眼科学   2355篇
药学   2430篇
  9篇
中国医学   729篇
肿瘤学   9428篇
  2024年   578篇
  2023年   5155篇
  2022年   1576篇
  2021年   3252篇
  2020年   5730篇
  2019年   2367篇
  2018年   7194篇
  2017年   7632篇
  2016年   8262篇
  2015年   8556篇
  2014年   11064篇
  2013年   12635篇
  2012年   4511篇
  2011年   4210篇
  2010年   7257篇
  2009年   9436篇
  2008年   3821篇
  2007年   2687篇
  2006年   3751篇
  2005年   2313篇
  2004年   1577篇
  2003年   1257篇
  2002年   1128篇
  2001年   1921篇
  2000年   1270篇
  1999年   1811篇
  1998年   2128篇
  1997年   1966篇
  1996年   1995篇
  1995年   1740篇
  1994年   1111篇
  1993年   930篇
  1992年   782篇
  1991年   656篇
  1990年   527篇
  1989年   532篇
  1988年   514篇
  1987年   394篇
  1986年   353篇
  1985年   300篇
  1984年   248篇
  1983年   302篇
  1982年   225篇
  1981年   196篇
  1980年   118篇
  1978年   122篇
  1977年   116篇
  1976年   85篇
  1974年   73篇
  1972年   71篇
排序方式: 共有10000条查询结果,搜索用时 218 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.
6.
The present letter to the editor is in response to the research “Outcomes of curative liver resection for hepatocellular carcinoma in patients with cirrhosis” by Elshaarawy et al in World J Gastroenterol 2021; 13(5): 424–439. The preoperative assessment of the liver reserve function in hepatocellular carcinoma (HCC) patients with cirrhosis is crucial, and there is no universal consensus on how to assess it. Based on a retrospective study, Elshaarawy et al investigated the impact of various classical clinical indicators on liver failure and the prognosis after hepatectomy in HCC patients with cirrhosis. We recommend that we should strive to explore new appraisal indicators, such as the indocyanine green retention rate at 15 min.  相似文献   
7.
8.
9.
10.
Near-infrared diffuse correlation spectroscopy/tomography (DCS/DCT) has recently emerged as a noninvasive measurement/imaging technology for tissue blood flow. In DCT studies, the high-dense collection of light temporal autocorrelation curves (g2(τ)) via fiber array are critical for image reconstruction of blood flow. Previously, the camera-based fiber array limits the field of view (FOV), precluding its applications on large-size human tissues. The line-shape fiber probe based on lens combination, which is predominantly used in current DCT studies, requires rotated-scanning over the surface of target tissue, substantially prolonging the measurement time and increasing the system instability. In this study, we design a noncontact optical probe for DCT based on collimating micro-lens fiber array, termed as FA-nc-DCT system. For each source/detector fiber, a single optical path was collimated by coupling with one micro-lens in the fiber array that is integrated in a square-shape base. Additionally, an 8×8 optical switch is used to share the hardware laser and detectors without spatial scanning. The FA-nc approach for the precise collection of g2(τ) curves was validated through a speed-varied phantom experiment and the human experiments of cuff occlusion, from which the expected value of the blood flow index (BFI) was obtained. Furthermore, the flow anomaly in the phantom and the ischemic muscle in human were accurately reconstructed from the FA-nc-DCT system, which is combined with the imaging framework based on the Nth-order linear algorithm that we recently created. Those outcomes demonstrated the great potential of FA-nc-DCT technology for fast and robust imaging of various diseases such as human breast cancers.  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