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   61929篇
  免费   4874篇
  国内免费   1648篇
耳鼻咽喉   16篇
儿科学   2226篇
妇产科学   582篇
基础医学   4368篇
口腔科学   153篇
临床医学   8765篇
内科学   19553篇
皮肤病学   65篇
神经病学   966篇
特种医学   1861篇
外科学   4672篇
综合类   12116篇
现状与发展   4篇
一般理论   3篇
预防医学   2804篇
眼科学   35篇
药学   6031篇
  77篇
中国医学   3975篇
肿瘤学   179篇
  2024年   150篇
  2023年   897篇
  2022年   1602篇
  2021年   2392篇
  2020年   2601篇
  2019年   2173篇
  2018年   2077篇
  2017年   1998篇
  2016年   1866篇
  2015年   1963篇
  2014年   4180篇
  2013年   4313篇
  2012年   3503篇
  2011年   3772篇
  2010年   2974篇
  2009年   2850篇
  2008年   2814篇
  2007年   3007篇
  2006年   2617篇
  2005年   2442篇
  2004年   1979篇
  2003年   1824篇
  2002年   1596篇
  2001年   1452篇
  2000年   1182篇
  1999年   1195篇
  1998年   1028篇
  1997年   980篇
  1996年   769篇
  1995年   718篇
  1994年   716篇
  1993年   539篇
  1992年   518篇
  1991年   467篇
  1990年   380篇
  1989年   359篇
  1988年   301篇
  1987年   281篇
  1986年   260篇
  1985年   292篇
  1984年   256篇
  1983年   157篇
  1982年   179篇
  1981年   162篇
  1980年   137篇
  1979年   112篇
  1978年   103篇
  1977年   81篇
  1976年   72篇
  1975年   55篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Loss of function variants in NOTCH1 cause left ventricular outflow tract obstructive defects (LVOTO). However, the risk conferred by rare and noncoding variants in NOTCH1 for LVOTO remains largely uncharacterized. In a cohort of 49 families affected by hypoplastic left heart syndrome, a severe form of LVOTO, we discovered predicted loss of function NOTCH1 variants in 6% of individuals. Rare or low-frequency missense variants were found in 16% of families. To make a quantitative estimate of the genetic risk posed by variants in NOTCH1 for LVOTO, we studied associations of 400 coding and noncoding variants in NOTCH1 in 1,085 cases and 332,788 controls from the UK Biobank. Two rare intronic variants in strong linkage disequilibrium displayed significant association with risk for LVOTO amongst European-ancestry individuals. This result was replicated in an independent analysis of 210 cases and 68,762 controls of non-European and mixed ancestry. In conclusion, carrying rare predicted loss of function variants in NOTCH1 confer significant risk for LVOTO. In addition, the two intronic variants seem to be associated with an increased risk for these defects. Our approach demonstrates the utility of population-based data sets in quantifying the specific risk of individual variants for disease-related phenotypes.  相似文献   
42.
43.
We describe a case of undiagnosed heart block which was detected during the postpartum surgical repair of a vaginal tear, and the subsequent investigations that confirmed diagnosis of atrio-ventricular heart block.  相似文献   
44.

Background

Lung ultrasound can accelerate the diagnosis of life-threatening diseases in adults with respiratory symptoms.

Objective

Systematically review the accuracy of lung ultrasonography (LUS) for emergency diagnosis of pneumonia, acute heart failure, and exacerbation of chronic obstructive pulmonary disease (COPD)/asthma in adults.

Methods

PubMed, Embase, Scopus, Web of Science, and LILACS (Literatura Latino Americana e do Caribe em Ciências da Saúde; until 2016) were searched for prospective diagnostic accuracy studies. Rutter-Gatsonis hierarchical summary receiver operating characteristic method was used to measure the overall accuracy of LUS and Reitsma bivariate model to measure the accuracy of the different sonographic signs. This review was previously registered in PROSPERO (Centre for Reviews and Dissemination, University of York, York, UK; CRD42016048085).

Results

Twenty-five studies were included: 14 assessing pneumonia, 14 assessing acute heart failure, and four assessing exacerbations of COPD/asthma. The area under the summary receiver operating characteristic curve of LUS was 0.948 for pneumonia, 0.914 for acute heart failure, and 0.906 for exacerbations of COPD/asthma. In patients suspected to have pneumonia, consolidation had sensitivity of 0.82 (95% confidence interval [CI] 0.74–0.88) and specificity of 0.94 (95% CI 0.85–0.98) for this disease. In acutely dyspneic patients, modified diffuse interstitial syndrome had sensitivity of 0.90 (95% CI 0.87–0.93) and specificity of 0.93 (95% CI 0.91–0.95) for acute heart failure, whereas B-profile had sensitivity of 0.93 (95% CI 0.72–0.98) and specificity of 0.92 (95% CI 0.79–0.97) for this disease in patients with respiratory failure. In patients with acute dyspnea or respiratory failure, the A-profile without PLAPS (posterior-lateral alveolar pleural syndrome) had sensitivity of 0.78 (95% CI 0.67–0.86) and specificity of 0.94 (95% CI 0.89–0.97) for exacerbations of COPD/asthma.

Conclusion

Lung ultrasound is an accurate tool for the emergency diagnosis of pneumonia, acute heart failure, and exacerbations of COPD/asthma.  相似文献   
45.
46.
The presented case reports on successful treatment with everolimus in a neonate with left ventricular giant rhabdomyoma. The authors used a different dosage regime compared to literature and documented rapid tumor regression by 3D echocardiography.  相似文献   
47.
目的观察认知行为干预在冠心病患者护理中的应用效果。方法选取本院2016年12月~2018年2月期间收治的53例冠心病患者,根据住院号奇偶性情况将其随机分为观察组(n=27)和对照组(n=26),对照组予以常规护理,观察组予以认知行为干预。比较两组患者控制态度评分、心理状况评分、生活质量改善情况及依从性。结果观察组控制态度评分、心理状况评分、生活质量改善情况及依从性与对照组比较,差异有统计学意义(P0.05)。结论在冠心病患者护理中给予认知行为干预应用效果极佳,可作为临床干预首选措施。  相似文献   
48.
不同强度运动对大鼠心脏降钙素基因相关肽的影响   总被引:5,自引:0,他引:5  
目的:探讨不同强度运动训练对降钙素基因相关肽(CGRP)在心脏组织中表达的影响及其作用机制。方法:将60只SD大鼠随机分为对照组(C组)、小强度运动组(LE组)、中等强度运动组(ME组)和大强度运动组(HE组),每组15只。建立8周不同强度运动训练动物模型,采用免疫组织化学法和计算机图像分析技术,对大鼠心脏形态结构进行观察,并进行心脏CGRP免疫组化分析。结果:8周小强度运动后,大鼠心脏CGRP表达较对照组变化不明显;8周中等强度运动后,大鼠心脏CGRP表达较对照组显著增加(P<0.05),HE染色、HBFP染色和变色酸2R亮绿染色显示心肌组织形态结构无明显改变,仅心肌纤维有轻度缺血缺氧改变;8周大强度运动后,大鼠心脏CGRP表达较对照组显著减少(P<0.05),HE染色、HBFP染色和变色酸2R亮绿染色显示心肌形态结构发生改变并存在明显的缺血缺氧损伤。结果表明,长期中等强度运动使心脏CGRP表达增加,改善了冠状循环和心肌血液供应,对心肌细胞具有保护作用;长期大强度运动使心脏CGRP对心肌细胞的保护作用减弱,可能是导致心肌发生缺血缺氧性损伤的重要原因之一。  相似文献   
49.
目的总结利用骨外固定器行胫骨迁移治疗血栓闭塞性脉管炎的护理经验.方法对35例血栓闭塞性脉管炎37条患肢应用骨外固定器迁移胫骨治疗.术前积极处理患肢、有效的心理护理,术后严密观察,做好骨外固定器迁移胫骨的护理.结果 32例间歇性跛行距离增加;27例夜间静息痛均得到缓解;7例足趾缺血坏死中除3例术后患肢缺血加重截肢外,余4例患肢供血改善,坏死区域结痂愈合;总有效率91.9%.结论全面、准确地评估患者,完善术前准备及术后正确迁移指导可提高骨外固定器行胫骨迁移治疗血栓闭塞性脉管炎的有效性.  相似文献   
50.
Abstract: The dependence of transient pressure characteristics of a ventricular assist device (VAD) on the compliance of its housing and cannulas was investigated in a mock circulation. The peak rate of change of pressure ( dP/dt max) values was greater in the cannulas than other compartments and was associated with valve closure-induced pressure oscillations. When cannula compliance was increased from 0.0057 to 0.0129 cm3/mm Hg, these values decreased by ˜20%, and outflow cannula pressure oscillation frequency decreased from 17.5 Hz by 35%. This trend was also apparent in the inflow. A VAD housing compliance increase from 0.0162 to 0.0483 cm3/mm Hg caused a dP/dt max decrease of 30% in both the blood chamber and the outflow cannula. The effect of this change on the inflow was weaker implying that housing absorbs the energy associated with outflow deceleration more effectively than the inflow. These findings suggest that increasing VAD housing and cannulas compliance can improve hydrodynamic performance.  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