全文获取类型
收费全文 | 230094篇 |
免费 | 16902篇 |
国内免费 | 6963篇 |
专业分类
耳鼻咽喉 | 1514篇 |
儿科学 | 3751篇 |
妇产科学 | 1680篇 |
基础医学 | 27943篇 |
口腔科学 | 3350篇 |
临床医学 | 30218篇 |
内科学 | 35741篇 |
皮肤病学 | 1600篇 |
神经病学 | 18439篇 |
特种医学 | 7417篇 |
外国民族医学 | 24篇 |
外科学 | 16254篇 |
综合类 | 37428篇 |
现状与发展 | 11篇 |
一般理论 | 25篇 |
预防医学 | 13922篇 |
眼科学 | 4396篇 |
药学 | 23433篇 |
142篇 | |
中国医学 | 10917篇 |
肿瘤学 | 15754篇 |
出版年
2023年 | 2564篇 |
2022年 | 4230篇 |
2021年 | 7978篇 |
2020年 | 7345篇 |
2019年 | 6964篇 |
2018年 | 6912篇 |
2017年 | 7126篇 |
2016年 | 7441篇 |
2015年 | 7257篇 |
2014年 | 12915篇 |
2013年 | 14378篇 |
2012年 | 12015篇 |
2011年 | 13415篇 |
2010年 | 11589篇 |
2009年 | 11162篇 |
2008年 | 11344篇 |
2007年 | 12447篇 |
2006年 | 11653篇 |
2005年 | 11022篇 |
2004年 | 9335篇 |
2003年 | 8298篇 |
2002年 | 6420篇 |
2001年 | 6319篇 |
2000年 | 5243篇 |
1999年 | 4747篇 |
1998年 | 3506篇 |
1997年 | 3188篇 |
1996年 | 2936篇 |
1995年 | 2896篇 |
1994年 | 2549篇 |
1993年 | 2262篇 |
1992年 | 1983篇 |
1991年 | 1716篇 |
1990年 | 1463篇 |
1989年 | 1301篇 |
1988年 | 1247篇 |
1987年 | 1048篇 |
1986年 | 806篇 |
1985年 | 925篇 |
1984年 | 917篇 |
1983年 | 581篇 |
1982年 | 704篇 |
1981年 | 591篇 |
1980年 | 515篇 |
1979年 | 454篇 |
1978年 | 374篇 |
1977年 | 316篇 |
1976年 | 344篇 |
1975年 | 231篇 |
1973年 | 202篇 |
排序方式: 共有10000条查询结果,搜索用时 912 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 观察结肠癌HCT116细胞健脾消癌方的条件培养液对HUVEC细胞管腔形成的影响,从PI3K/Akt生物轴调控角度探讨其作用机制。方法 培养HCT116细胞,细胞设3组:对照组,健脾消癌方组(加入15%健脾消癌方含药血清)及人参皂苷Rg3组;制备HCT116细胞健脾消癌方条件培养液(分组及制备方法见实验方法),用条件培养液干预HUVEC(脐静脉内皮细胞,Human Umbilical Vein Endothelial Cells),Matrigel基质胶法检测HCT116细胞健脾消癌方条件培养液对HUVEC小管形成的影响。随后采用蛋白免疫印迹法(Western blot)检测各组HCT116细胞磷脂酰肌醇3-激酶(PI3K)、蛋白激酶B(Akt)、p-Akt、VEGF(血管内皮生长因子,Vascular endothelial growth factor)蛋白表达。最后在结肠癌HCT116荷瘤小鼠中验证健脾消癌方对肿瘤生长速度的影响,并经瘤组织VEGF蛋白表达、CD31免疫组化染色检测肿瘤内血管生成情况。结果 模型组HUVEC细胞管腔形成较空白血清组显著增加(P<0.05);健脾消癌方组及人参皂苷Rg3组较模型组HUVEC细胞管腔形成显著减少(P<0.01)。p-Akt和VEGF蛋白表达水平模型组高于空白血清组(P<0.05),健脾消癌方组及人参皂苷Rg3组显著低于模型组(P<0.01);PI3K、Akt蛋白表达量组间差异无统计学意义。与对照组比较,模型组荷瘤小鼠肿瘤体积显著性增大,瘤组织内VEGF表达、CD31阳性面积显著性增加,差异有统计学意义(P<0.05);与模型组比较,健脾消癌方组及人参皂苷Rg3组荷瘤小鼠肿瘤体积显著减小,瘤组织内VEGF表达、CD31阳性面积降低,差异有统计学意义(P<0.05)。结论 健脾消癌方可抑制肿瘤的血管生成和生长,其作用机制可能与PI3K/Akt生物轴调控VEGF表达有关。 相似文献
4.
5.
6.
7.
Ludefu Su Yu Liu Yanhong Tang Mingmin Zhou Liang Xiong Congxin Huang 《International journal of clinical and experimental pathology》2021,14(4):408
Background and objective: Myocardial infarction (MI) is a common critical disease of the cardiovascular system. The process of MI is often accompanied by the excessive activation of cardiac sympathetic nerves, which leads to arrhythmia. Resiniferatoxin (RTX) is a transient receptor potential vanilloid 1 (TRPV1), involved in the cardiac sympathetic afferent reflex. However, whether RTX can reduce the occurrence of arrhythmia and exert a cardioprotective effect by inhibiting the sympathetic reflex during MI is still unknown. Methods: The left anterior descending artery of cardiac was clamped to construct a model of MI. RTX (50 μg/ml) was used by epicardial application in MI rats. Ventricular electrophysiologic properties were continuously monitored by a body surface ECG. Yrosine hydroxylase (TH) and growth associated protein 43 (GAP43) were detected by Immunofluorescence staining. Connexin43 and transforming growth factor beta receptor 1 (TGF-β1) were detected by western blot. Norepinephrine (NE) and BNP levels in blood and tissue were determined by ELISA. Cardiac function was assessed by echocardiography. Results: The ERP, APD90, QRS, QT and the Tend-Tpeak intervals in MI rats were all prolonged, but decreased after RTX treatment (n = 3, P<0.05). In contrast, the RR interval was shortened in the MI group, but prolonged in the MI+RTX group (n = 3, P<0.05). RTX treatment significantly reduced ventricular arrhythmias after MI. TH- and GAP43-positive nerve densities and TGF-β1, and cx-43 protein expression were up-regulated in the MI group compared to the sham group, and they were decreased in the MI+RTX group compared to the MI group (n = 3, P<0.05). RTX can decrease serum and tissue NE and BNP levels (n = 3, P<0.05). RTX pretreatment significantly decreased heart rate, HW/BW ratio and LVIDS, and increased LVEF andLVFS values (n = 3, P<0.05). Conclusion: RTX improved cardiac dysfunction, ventricular electrophysiologic properties, and sympathetic nerve remodeling in rats with MI by inhibiting the excessive cardiac sympathetic drive. 相似文献
8.
9.
10.