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   3453572篇
  免费   297908篇
  国内免费   15942篇
耳鼻咽喉   48527篇
儿科学   111072篇
妇产科学   90930篇
基础医学   547306篇
口腔科学   94278篇
临床医学   310868篇
内科学   608346篇
皮肤病学   91780篇
神经病学   293855篇
特种医学   137516篇
外国民族医学   412篇
外科学   541021篇
综合类   106560篇
现状与发展   33篇
一般理论   2210篇
预防医学   286028篇
眼科学   79746篇
药学   241575篇
  48篇
中国医学   11215篇
肿瘤学   164096篇
  2021年   56525篇
  2020年   36647篇
  2019年   59177篇
  2018年   72886篇
  2017年   55548篇
  2016年   61018篇
  2015年   75746篇
  2014年   110415篇
  2013年   175419篇
  2012年   92545篇
  2011年   92952篇
  2010年   118177篇
  2009年   122617篇
  2008年   80190篇
  2007年   83650篇
  2006年   94381篇
  2005年   90368篇
  2004年   91469篇
  2003年   82683篇
  2002年   73027篇
  2001年   105090篇
  2000年   97755篇
  1999年   98086篇
  1998年   65863篇
  1997年   63525篇
  1996年   61442篇
  1995年   56819篇
  1994年   50999篇
  1993年   47363篇
  1992年   69465篇
  1991年   66941篇
  1990年   64223篇
  1989年   63332篇
  1988年   59245篇
  1987年   57719篇
  1986年   55054篇
  1985年   55030篇
  1984年   49440篇
  1983年   45356篇
  1982年   41756篇
  1981年   39249篇
  1980年   36921篇
  1979年   41484篇
  1978年   36145篇
  1977年   32996篇
  1976年   30412篇
  1975年   29722篇
  1974年   31025篇
  1973年   29874篇
  1972年   28246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.
Cao  Jie  Xie  Chengyu  Hou  Zhiru 《Ecotoxicology (London, England)》2022,31(2):259-270
Ecotoxicology - Soil heavy metal pollution evaluations are a necessary measure for mine ecological control projects. In this study, the heavy metals Pb, Zn and Cd were studied in mining areas,...  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   
8.
9.

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   
10.
Background: Breast cancer (BC) is the most common malignant tumor in women, and its morbidity and mortality are increasing each year, due to the lack of specific clinical symptoms in the early stage of BC, and the lack of diagnostic methods for early breast cancer. Therefore, identifying an effective diagnostic method for early BC has become urgent. Materials and Methods: Breast lesions with a histological diagnosis that were examined by ultrasonic elastography (UE) in our department from June 2020 to December 2021 were reviewed. qRT-PCR was performed to measure the expression levels of miR-144-5p and miR-26b-5p in the plasma of patients with BC. The receiver operating characteristics (ROC) curve and area under the curve (AUC) were used to investigate the potential diagnostic value of miR- 144-5p, miR-26b-5p and the elastographic score in BC. Results: The ultrasonic elastography score(UES) was found to be significantly upregulated in BC compared with that in benign breast lesions, and the AUC, sensitivity and specificity were 0.809, 0.717 and 0.806 for distinguishing BC from benign breast lesions, respectively. miR-144-5p and miR-26b- 5p were found to be upregulated in the plasma of BC patients, and miR-144-5p+miR-26b-5p had 0.781 sensitivity and 0.780 specificity for the diagnosis of BC. Furthermore, we found that the diagnostic performance of miR-144-5p and miR-26b-5p combined with UES for BC had 0.913 sensitivity and 0.890 specificity. Conclusions: The combination of plasma miR-144-5p, miR-26b-5p and UES has a very high clinical application value for the early detection of BC.  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