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   1695321篇
  免费   176214篇
  国内免费   4566篇
耳鼻咽喉   23799篇
儿科学   57661篇
妇产科学   47434篇
基础医学   236277篇
口腔科学   50494篇
临床医学   167789篇
内科学   347875篇
皮肤病学   45817篇
神经病学   149240篇
特种医学   66201篇
外国民族医学   488篇
外科学   260044篇
综合类   33889篇
现状与发展   42篇
一般理论   533篇
预防医学   131322篇
眼科学   38449篇
药学   114688篇
  2篇
中国医学   4668篇
肿瘤学   99389篇
  2021年   15337篇
  2020年   16800篇
  2019年   24039篇
  2018年   31381篇
  2017年   28626篇
  2016年   31817篇
  2015年   33928篇
  2014年   42804篇
  2013年   57221篇
  2012年   58642篇
  2011年   60582篇
  2010年   44457篇
  2009年   41927篇
  2008年   55492篇
  2007年   57084篇
  2006年   58745篇
  2005年   56182篇
  2004年   53196篇
  2003年   50881篇
  2002年   49097篇
  2001年   79850篇
  2000年   80795篇
  1999年   67421篇
  1998年   20179篇
  1997年   18234篇
  1996年   18194篇
  1995年   16970篇
  1994年   15014篇
  1993年   13980篇
  1992年   48423篇
  1991年   45889篇
  1990年   43822篇
  1989年   41737篇
  1988年   38171篇
  1987年   37260篇
  1986年   34632篇
  1985年   32963篇
  1984年   25174篇
  1983年   21229篇
  1982年   13038篇
  1979年   22003篇
  1978年   15655篇
  1977年   13002篇
  1976年   12113篇
  1975年   12665篇
  1974年   15080篇
  1973年   14546篇
  1972年   13653篇
  1971年   12439篇
  1970年   11776篇
排序方式: 共有10000条查询结果,搜索用时 203 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.
7.
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   
8.
9.
10.

The exercise pressor reflex is a feedback mechanism engaged upon stimulation of mechano- and metabosensitive skeletal muscle afferents. Activation of these afferents elicits a reflex increase in heart rate, blood pressure, and ventilation in an intensity-dependent manner. Consequently, the exercise pressor reflex has been postulated to be one of the principal mediators of the cardiorespiratory responses to exercise. In this updated review, we will discuss classical and recent advancements in our understating of the exercise pressor reflex function in both human and animal models. Particular attention will be paid to the afferent mechanisms and pathways involved during its activation, its effects on different target organs, its potential role in the abnormal cardiovascular response to exercise in diseased states, and the impact of age and biological sex on these responses. Finally, we will highlight some unanswered questions in the literature that may inspire future investigations in the field.

  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