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   1525318篇
  免费   114739篇
  国内免费   5085篇
耳鼻咽喉   19003篇
儿科学   48596篇
妇产科学   40065篇
基础医学   221481篇
口腔科学   39759篇
临床医学   149313篇
内科学   296894篇
皮肤病学   29217篇
神经病学   131464篇
特种医学   56974篇
外国民族医学   379篇
外科学   214799篇
综合类   30983篇
现状与发展   2篇
一般理论   624篇
预防医学   127561篇
眼科学   33782篇
药学   111789篇
  7篇
中国医学   3430篇
肿瘤学   89020篇
  2021年   14973篇
  2019年   15819篇
  2018年   21408篇
  2017年   15997篇
  2016年   17361篇
  2015年   19960篇
  2014年   27811篇
  2013年   41570篇
  2012年   58633篇
  2011年   62013篇
  2010年   35650篇
  2009年   32851篇
  2008年   56115篇
  2007年   59148篇
  2006年   58970篇
  2005年   57288篇
  2004年   54400篇
  2003年   51249篇
  2002年   49467篇
  2001年   62531篇
  2000年   63769篇
  1999年   54019篇
  1998年   16970篇
  1997年   15090篇
  1996年   13483篇
  1995年   13833篇
  1994年   12872篇
  1993年   12096篇
  1992年   42326篇
  1991年   41527篇
  1990年   40101篇
  1989年   37963篇
  1988年   35155篇
  1987年   34227篇
  1986年   32674篇
  1985年   31230篇
  1984年   23745篇
  1983年   20186篇
  1982年   12560篇
  1981年   11031篇
  1979年   21150篇
  1978年   15222篇
  1977年   12389篇
  1976年   12188篇
  1975年   12342篇
  1974年   15047篇
  1973年   14689篇
  1972年   13511篇
  1971年   12558篇
  1970年   11571篇
排序方式: 共有10000条查询结果,搜索用时 25 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.
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   
3.
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   
4.
Die Anaesthesiologie - Phantomschmerzen haben eine hohe Prävalenz nach Majoramputationen und sind mit einer zusätzlichen Einschränkung der Lebensqualität verbunden....  相似文献   
5.

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   
6.
7.
8.
9.

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   
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