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   3461674篇
  免费   302723篇
  国内免费   38559篇
耳鼻咽喉   46141篇
儿科学   103802篇
妇产科学   84813篇
基础医学   541438篇
口腔科学   89039篇
临床医学   324632篇
内科学   593364篇
皮肤病学   88994篇
神经病学   286851篇
特种医学   136664篇
外国民族医学   584篇
外科学   522695篇
综合类   162065篇
现状与发展   107篇
一般理论   2196篇
预防医学   283129篇
眼科学   80620篇
药学   251262篇
  440篇
中国医学   32865篇
肿瘤学   171255篇
  2022年   25669篇
  2021年   71097篇
  2020年   48082篇
  2019年   68078篇
  2018年   80623篇
  2017年   63652篇
  2016年   68073篇
  2015年   87990篇
  2014年   125784篇
  2013年   188804篇
  2012年   110971篇
  2011年   113003篇
  2010年   133531篇
  2009年   135002篇
  2008年   90672篇
  2007年   91801篇
  2006年   101804篇
  2005年   97252篇
  2004年   92462篇
  2003年   83149篇
  2002年   71509篇
  2001年   95828篇
  2000年   88606篇
  1999年   91518篇
  1998年   67288篇
  1997年   65427篇
  1996年   62470篇
  1995年   57772篇
  1994年   51550篇
  1993年   47544篇
  1992年   60534篇
  1991年   57030篇
  1990年   53952篇
  1989年   53122篇
  1988年   49437篇
  1987年   48195篇
  1986年   46074篇
  1985年   46075篇
  1984年   43384篇
  1983年   40127篇
  1982年   39929篇
  1981年   37719篇
  1980年   35627篇
  1979年   35207篇
  1978年   32204篇
  1977年   29733篇
  1976年   27298篇
  1975年   25810篇
  1974年   26317篇
  1973年   25064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.
Quality of Life Research - The COVID-19 pandemic might add to the stressors experienced by people living with rheumatic diseases. This study aimed to examine rheumatic patients’ functional...  相似文献   
4.
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   
5.
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   
6.

Physical activity brings significant health benefits to middle-aged adults, although the research to date has been focused on late adulthood. This study aims to examine how ageing affects the self-reported and accelerometer-derived measures of physical activity levels in middle-aged adults. We employed the data recorded in the UK Biobank and analysed the physical activity levels of 2,998 participants (1381 men and 1617 women), based on self-completion questionnaire and accelerometry measurement of physical activity. We also assessed the musculoskeletal health of the participants using the dual-energy X-ray absorptiometry (DXA) measurements provided by the UK Biobank. Participants were categorised into three groups according to their age: group I younger middle-aged (40 to 49 years), group II older middle-aged (50 to 59 years), and group III oldest middle-aged (60 to 69 years). Self-reported physical activity level increased with age and was the highest in group III, followed by group II and I (P?<?0.05). On the contrary, physical activity measured by accelerometry decreased significantly with age from group I to III (P?<?0.05), and the same pertained to the measurements of musculoskeletal health (P?<?0.05). It was also shown that middle-aged adults mostly engaged in low and moderate intensity activities. The opposing trends of the self-reported and measured physical activity levels may suggest that middle-aged adults over-report their activity level as they age. They should be aware of the difference between their perceived and actual physical activity levels, and objective measures would be useful to prevent the decline in musculoskeletal health.

  相似文献   
7.
目的 对比研究朝鲜淫羊藿酸性多糖酯化还原前后的理化特性,并探讨其改善油酸诱导的肝癌HepG2细胞脂质堆积活性的差异。方法 采用高效凝胶渗透色谱法测定朝鲜淫羊藿酸性多糖(EFPA)的均一性和分子量,高效液相色谱法测定EFPA和酯化还原后朝鲜淫羊藿酸性多糖(EFPA-R)的单糖组成;采用油酸(OA)处理HepG2细胞诱导建立脂质蓄积模型,不同浓度EFPA与EFPA-R(10、30、100、300 μg·mL-1)分别和OA共同作用于细胞24 h,采用CCK-8试剂盒测定细胞存活率,油红O染色观察细胞内脂滴蓄积情况,并采用试剂盒测定细胞内总胆固醇(TC)、甘油三酯(TG)含量。结果 EFPA为成分均一的多糖组分,分子量为125.8 kDa,由甘露糖、葡萄糖、半乳糖、葡萄糖醛酸和阿拉伯糖组成,摩尔比为1.7∶7.4∶1.4∶1.8∶1.0,葡萄糖占比最大,EFPA-R由甘露糖、葡萄糖、半乳糖和阿拉伯糖组成,摩尔比为0.8∶10.6∶2.1∶1.0;在10-300 μg·mL-1范围内,EFPA和EFPA-R对HepG2细胞的抑制作用较弱,作为给药浓度;与空白组相比,模型组细胞中TC、TG含量显著升高(P < 0.01),细胞内红色脂滴显著增多,与模型组相比,EFPA可显著降低细胞中TC、TG含量(P < 0.01),明显减少细胞内红色脂滴(P < 0.05或P < 0.01),EFPA-R干预后细胞则无明显变化。结论 EFPA可明显改善HepG2细胞脂质堆积情况,且呈现剂量依赖性,而半乳糖醛酸(GalA)的存在可能是其抑制HepG2细胞脂质蓄积的关键因素。  相似文献   
8.
目的收集特重度烧伤(总TBSA50%以上或三度TBSA20%以上或伴有严重并发症者)患者围术期凝血指标(APTT、PT、FIB、DD和PLT),分析静吸复合麻醉对患者凝血功能的影响及其临床意义。 方法选取近3年内蒙古医科大学第三附属医院烧伤外科收治的特重度烧伤患者148例,根据入院14 d内的预后分为死亡组和生存组,生存组男性129例,女性9例;年龄24~59岁,平均(43.30±12.90)岁。死亡组男性8例,女性2例;年龄26~63岁,平均(46.19±15.41)岁。收集入院时(T0),术前(早晨入手术室前,T1),术毕(送至PACU未拔除气管导管前,T2)及术后2 d(T3)4个时间点的凝血指标,比较两组凝血指标动态差异。 结果死亡组休克期输液量、累计血浆、红细胞输入量显著高于生存组(P<0.01)。T0时,生存组的FIB(1.78±0.32)显著高于死亡组(1.26±0.07)(P<0.05);T2时,两组APTT、PT均显著缩短(P<0.05),生存组的FIB(3.86±0.40)显著高于死亡组(2.45±1.02)(P<0.05);T3时,死亡组PLT显著低于生存组(P<0.01)。 结论特重度烧伤患者在围手术期易出现高凝状态,并且这可能导致患者死亡。静吸复合麻醉和围术期大量液体复苏会促进患者的高凝状态。  相似文献   
9.
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