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   242085篇
  免费   19997篇
  国内免费   9201篇
耳鼻咽喉   1365篇
儿科学   5062篇
妇产科学   1999篇
基础医学   29823篇
口腔科学   3647篇
临床医学   27261篇
内科学   29089篇
皮肤病学   1897篇
神经病学   14517篇
特种医学   8097篇
外国民族医学   25篇
外科学   35144篇
综合类   40278篇
现状与发展   16篇
一般理论   27篇
预防医学   14939篇
眼科学   5054篇
药学   24072篇
  66篇
中国医学   13444篇
肿瘤学   15461篇
  2024年   528篇
  2023年   3365篇
  2022年   6669篇
  2021年   9674篇
  2020年   8401篇
  2019年   8090篇
  2018年   7898篇
  2017年   8157篇
  2016年   8442篇
  2015年   8419篇
  2014年   13846篇
  2013年   15756篇
  2012年   12701篇
  2011年   14419篇
  2010年   12427篇
  2009年   11914篇
  2008年   11940篇
  2007年   12895篇
  2006年   11989篇
  2005年   11381篇
  2004年   9722篇
  2003年   8626篇
  2002年   6664篇
  2001年   6375篇
  2000年   5128篇
  1999年   4621篇
  1998年   3459篇
  1997年   3046篇
  1996年   3050篇
  1995年   2826篇
  1994年   2429篇
  1993年   2131篇
  1992年   1844篇
  1991年   1587篇
  1990年   1324篇
  1989年   1257篇
  1988年   1123篇
  1987年   904篇
  1986年   697篇
  1985年   799篇
  1984年   787篇
  1983年   481篇
  1982年   599篇
  1981年   525篇
  1980年   446篇
  1979年   378篇
  1978年   295篇
  1977年   249篇
  1976年   283篇
  1975年   175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.
4.
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   
5.
ObjectivesTo confirm what impairments are present in runners with Achilles tendinopathy (AT) and explore the variance of AT severity in an adequately powered study.DesignCase-control study.SettingTwo private physiotherapy clinics in Australia and Spain.ParticipantsForty-four recreational male runners with AT and 44 healthy controls matched by age, height, and weight.Main outcome measuresDemographics, activity (IPAQ-SF), pain and function (VISA-A), pain during hopping (Hop pain VAS), hopping duration, psychological factors (TSK-11, PASS20), and physical tests regarding lower-limb maximal strength and endurance.ResultsBody mass index (BMI), activity, VISA-A, pain, and duration of hopping, TSK-11, PASS20, standing heel raise to failure, seated heel raise and leg extension 6RM, hip extension and abduction isometric torque were significantly different between groups (P < 0.05) with varied effect sizes (V = 0.22, d range = 0.05–4.18). 46% of AT severity variance was explained by higher BMI (β = −0.41; p = 0.001), weaker leg curl 6RM (β = 0.32; p = 0.009), and higher pain during hopping (β = −0.43; p = 0.001).ConclusionRunners with AT had lower activity levels, lower soleus strength, and were less tall. BMI, pain during hopping, and leg curl strength explained condition severity. This information, identified with clinically applicable tools, may guide clinical assessment, and inform intervention development.  相似文献   
6.
7.
8.
黄嘉敏  赵霞  孙宜康  李宛莹  苟继周  周光德  何清 《肝脏》2022,27(1):20-22,37
目的了解何首乌致药物性肝损伤(Polygonum multiflorum-associated drug induce liver injury,PM-DILI)的临床病理学特点。方法收集2019年3月1日至2021年3月1日深圳市第三人民医院收治的8例PM-DILI患者临床资料。肝穿组织进行苏木素-伊红染色、网状纤维染色、Masson三色染色、铁、铜特殊染色和免疫组织化学染色,显微镜下观察分析。结果8例PM-DILI患者男女比为1∶1,平均年龄43岁,其中6例为急性PM-DILI,2例慢性为PM-DILI。入院血清学检查异常主要包括转氨酶升高和淤胆均为7例。主要组织病理学改变为点灶状坏死8例、界面炎5例、融合坏死4例,融合坏死以肝腺泡3带为主,不伴或伴少数炎细胞浸润;胆汁淤积5例,为肝腺泡3带的肝细胞、毛细胆管内淤胆,不伴或伴少数炎细胞浸润;中央静脉炎3例;病程长者可发生肝纤维化,甚至肝硬化2例。结论肝腺泡3带为主的急性淤胆和肝细胞坏死是PM-DILI主要组织学表现,严重者可发生静脉炎等血管损伤。  相似文献   
9.
BackgroundHamstring strain injuries are the most common type of injury in elite football and are associated with a high risk of reinjury, particularly those involving the intramuscular tendon (IMT). Limited information is available regarding the rehabilitation and return to sport (RTS) processes following such injuries. This case study describes the clinical presentation of an elite football player following IMT hamstring injury, their on- and off-pitch rehabilitation alongside performance monitoring throughout RTS and beyond.Case scenarioAn elite football player suffered a grade 2c hamstring injury during an English Premier League (EPL) match. The player underwent early post-injury management, alongside progressive off-pitch physical preparation. The ‘control-chaos continuum’ was used as a framework for on-pitch rehabilitation to prepare the player for a return to full team training and competition. Objective and subjective markers of the player's response to progressive on- and off-pitch loading were monitored throughout RTS and beyond.OutcomesThe player returned to on-pitch rehabilitation after 11 days, to full team training having achieved weekly pre-injury chronic running load outputs after 35 days and played in the EPL 40 days post-injury. The player did not suffer reinjury for the rest of the EPL season.ConclusionAn understanding the unique structural and mechanical properties of the IMT, alongside expected RTS timeframes are important to inform rehabilitation and decision-making processes post-injury. Performance and frequent load-response monitoring throughout RTS and beyond, in conjunction with practitioner experience and effective communication are critical in facilitating effective RTS and reduce risk of reinjury following IMT injury.  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