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   213889篇
  免费   68592篇
  国内免费   1105篇
耳鼻咽喉   4106篇
儿科学   7880篇
妇产科学   3896篇
基础医学   25573篇
口腔科学   11567篇
临床医学   39484篇
内科学   53730篇
皮肤病学   11422篇
神经病学   28598篇
特种医学   7731篇
外科学   37397篇
综合类   297篇
现状与发展   40篇
一般理论   53篇
预防医学   19664篇
眼科学   4213篇
药学   10084篇
中国医学   1095篇
肿瘤学   16756篇
  2024年   790篇
  2023年   5276篇
  2022年   1294篇
  2021年   4290篇
  2020年   10767篇
  2019年   13203篇
  2018年   15960篇
  2017年   17539篇
  2016年   18844篇
  2015年   18560篇
  2014年   21138篇
  2013年   24479篇
  2012年   9746篇
  2011年   9979篇
  2010年   15965篇
  2009年   14330篇
  2008年   8227篇
  2007年   6407篇
  2006年   7454篇
  2005年   5710篇
  2004年   5023篇
  2003年   4792篇
  2002年   4737篇
  2001年   5080篇
  2000年   5039篇
  1999年   3621篇
  1998年   2615篇
  1997年   2359篇
  1996年   2310篇
  1995年   1992篇
  1994年   1398篇
  1993年   1216篇
  1992年   1047篇
  1991年   870篇
  1990年   742篇
  1989年   816篇
  1988年   707篇
  1987年   606篇
  1986年   597篇
  1985年   586篇
  1984年   581篇
  1983年   561篇
  1982年   482篇
  1981年   414篇
  1980年   326篇
  1979年   296篇
  1978年   301篇
  1977年   310篇
  1976年   279篇
  1975年   229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.
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   
4.
Die Anaesthesiologie - Phantomschmerzen haben eine hohe Prävalenz nach Majoramputationen und sind mit einer zusätzlichen Einschränkung der Lebensqualität verbunden....  相似文献   
5.
6.
7.
8.
9.
Intratumor heterogeneity is a main cause of the dismal prognosis of glioblastoma (GBM). Yet, there remains a lack of a uniform assessment of the degree of heterogeneity. With a multiscale approach, we addressed the hypothesis that intratumor heterogeneity exists on different levels comprising traditional regional analyses, but also innovative methods including computer-assisted analysis of tumor morphology combined with epigenomic data. With this aim, 157 biopsies of 37 patients with therapy-naive IDH-wildtype GBM were analyzed regarding the intratumor variance of protein expression of glial marker GFAP, microglia marker Iba1 and proliferation marker Mib1. Hematoxylin and eosin stained slides were evaluated for tumor vascularization. For the estimation of pixel intensity and nuclear profiling, automated analysis was used. Additionally, DNA methylation profiling was conducted separately for the single biopsies. Scoring systems were established to integrate several parameters into one score for the four examined modalities of heterogeneity (regional, cellular, pixel-level and epigenomic). As a result, we could show that heterogeneity was detected in all four modalities. Furthermore, for the regional, cellular and epigenomic level, we confirmed the results of earlier studies stating that a higher degree of heterogeneity is associated with poorer overall survival. To integrate all modalities into one score, we designed a predictor of longer survival, which showed a highly significant separation regarding the OS. In conclusion, multiscale intratumor heterogeneity exists in glioblastoma and its degree has an impact on overall survival. In future studies, the implementation of a broadly feasible heterogeneity index should be considered.  相似文献   
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