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   7828篇
  免费   653篇
  国内免费   217篇
耳鼻咽喉   28篇
儿科学   166篇
妇产科学   39篇
基础医学   825篇
口腔科学   485篇
临床医学   1213篇
内科学   1756篇
皮肤病学   100篇
神经病学   295篇
特种医学   219篇
外国民族医学   1篇
外科学   1141篇
综合类   1043篇
预防医学   302篇
眼科学   57篇
药学   621篇
  3篇
中国医学   355篇
肿瘤学   49篇
  2024年   7篇
  2023年   168篇
  2022年   198篇
  2021年   812篇
  2020年   482篇
  2019年   347篇
  2018年   350篇
  2017年   344篇
  2016年   286篇
  2015年   365篇
  2014年   486篇
  2013年   619篇
  2012年   401篇
  2011年   415篇
  2010年   364篇
  2009年   351篇
  2008年   350篇
  2007年   353篇
  2006年   278篇
  2005年   252篇
  2004年   211篇
  2003年   175篇
  2002年   168篇
  2001年   118篇
  2000年   93篇
  1999年   77篇
  1998年   58篇
  1997年   72篇
  1996年   38篇
  1995年   50篇
  1994年   48篇
  1993年   27篇
  1992年   45篇
  1991年   35篇
  1990年   30篇
  1989年   24篇
  1988年   13篇
  1987年   24篇
  1986年   14篇
  1985年   23篇
  1984年   21篇
  1983年   14篇
  1982年   23篇
  1981年   12篇
  1980年   16篇
  1979年   16篇
  1978年   5篇
  1977年   5篇
  1976年   8篇
  1972年   2篇
排序方式: 共有8698条查询结果,搜索用时 171 毫秒
41.
42.
机械血栓切除术可治疗伴大血管闭塞的前循环和后循环急性缺血性脑卒中。机械血栓切除术失败后仍应进行支架植入术;接触抽吸术与支架取栓术的优劣难分仲伯;伴大血管闭塞的动脉粥样硬化性前循环急性缺血性脑卒中,血管成形术和(或)支架置入术要优于支架取栓术;支架取栓术加动脉内溶栓治疗有叠加效应,但机械血栓切除术加静脉溶栓则无叠加效应;远程缺血预处理和替罗非班有减少手术并发症的功效;紫杉醇洗脱支架和新型支架是值得推广的新型血管内治疗装置。  相似文献   
43.
44.
The Japanese Respiratory Society 2017 guidelines strongly recommend switching from intravenous (IV) to oral antibiotics in patients with community-acquired pneumonia (CAP), following improvement in clinical symptoms and laboratory findings. Here, we retrospectively investigated the real-world, nationwide treatment and switching patterns for hospitalized patients with CAP in Japan using administrative data from 372 Japanese Diagnosis Procedure Combination hospitals from April 2010 to December 2018. Hospitalizations for CAP (patient age ≥20 years) with an A-DROP classification for CAP severity and IV antibiotics initiated on the admission date were included. Overall, 210,314 hospitalizations (moderate CAP: 61.7%) in 183,607 patients were analyzed. The median (interquartile range [IQR]) age at admission was 79 (70–86) years. Penicillin (51.9%) and cephalosporin (38.9%) were the most common IV antibiotic classes used and the median (IQR) duration of IV use was 8 (6–11) days. Switching to oral antibiotics during a hospitalization occurred in 30.1% (n = 63,311) of patients after a median (IQR) of 7 (5–10) days of IV treatment. The most frequently used oral antibiotic classes after a switch were fluoroquinolone (45.9%) and penicillin (24.8%). The switch rate was higher among hospitalizations with milder CAP, in respiratory medicine ward and in larger hospitals. The overall switch rates did not change over the study period. The findings from this analysis suggest that early switch from IV to oral antibiotics was not widely implemented during the 8 years of the study period. Further observation will be needed to see the potential impact of the guidelines update in 2017 in Japan.  相似文献   
45.
目的探究无创机械通气对慢性阻塞性肺疾病(COPD)合并呼吸衰竭患者认知功能及睡眠质量的影响。方法选取我院接收的COPD合并呼吸衰竭患者104例,采用随机法将其分成试验组和对照组,各52例。对照组进行常规治疗,试验组进行无创机械通气治疗。比较两组的治疗效果。结果治疗后,试验组的肺功能指标均优于对照组(P<0.05)。治疗后,试验组的MMSE评分高于对照组及治疗前,PSQI评分低于对照组及治疗前(P<0.05)。试验组的治疗显效率高于对照组(P<0.05)。结论无创机械通气疗法可以显著提升COPD合并呼吸衰竭患者的肺功能、认知功能及睡眠质量,进而提升患者的生活质量。  相似文献   
46.
This research investigated the effects of different thermoplastics types and different kinds of straw on selected properties of polymer-straw boards. Polyethylene, polyethylene, and polystyrene of virgin and of recycled origin were used for bonding the boards. Three kinds of straw were used: rape (Brassica napus L. var. napus), triticale (Triticosecale Witt b m.), and rye (Secale L.). Five-layer polymer-straw boards were produced. The obtained boards differed in both the materials they were made of and the moisture content (7, 25, and 2% for the core, the middle, and the face layers, respectively), and 30% of straw particles were substituted with thermoplastics added to the face layers. It was found that properties of polymer-straw boards strongly depend on both the kind of straw and the type of polymer used. The best mechanical properties were obtained for rye straw and polystyrene or recycled polymers, whereas the best hydrophobic properties were observed for rape straw combined with recycled polyethylene or polypropylene. Although recycled polymers improved the hydrophobic properties of the boards, they impaired their mechanical properties in comparison with the reference ones. However, in terms of bending strength, they still met the requirements for heavy duty load-bearing boards for use in humid conditions (20 MPa for P7 boards according to EN 312).  相似文献   
47.
BackgroundPretest probability (PTP) calculators utilize epidemiological-level findings to provide patient-level risk assessment of obstructive coronary artery disease (CAD). However, their limited accuracies question whether dissimilarities in risk factors necessarily result in differences in CAD. Using patient similarity network (PSN) analyses, we wished to assess the accuracy of risk factors and imaging markers to identify ≥50% luminal narrowing on coronary CT angiography (CCTA) in stable chest-pain patients.MethodsWe created four PSNs representing: patient characteristics, risk factors, non-coronary imaging markers and calcium score. We used spectral clustering to group individuals with similar risk profiles. We compared PSNs to a contemporary PTP score incorporating calcium score and risk factors to identify ≥50% luminal narrowing on CCTA in the CT-arm of the PROMISE trial. We also conducted subanalyses in different age and sex groups.ResultsIn 3556 individuals, the calcium score PSN significantly outperformed patient characteristic, risk factor, and non-coronary imaging marker PSNs (AUC: 0.81 vs. 0.57, 0.55, 0.54; respectively, p ?< ?0.001 for all). The calcium score PSN significantly outperformed the contemporary PTP score (AUC: 0.81 vs. 0.78, p ?< ?0.001), and using 0, 1–100 and ?> ?100 cut-offs provided comparable results (AUC: 0.81 vs. 0.81, p ?= ?0.06). Similar results were found in all subanalyses.ConclusionCalcium score on its own provides better individualized obstructive CAD prediction than contemporary PTP scores incorporating calcium score and risk factors. Risk factors may not be able to improve the diagnostic accuracy of calcium score to predict ≥50% luminal narrowing on CCTA.  相似文献   
48.
目的:通过交叉对比神经网络(CCNN)实现心音信号的自动分类,从而对心血管疾病进行早期诊断。方法:实验基于PhysioNet/Cinc 2016心音数据库。训练集和测试集数据来自互斥的健康受试者/病理患者,并以4:1的比例进行划分,输入CCNN。CCNN利用深度卷积神经网络进行特征提取,结合基于信息的相似度度量理论(IBS),对特征向量间的相似性进行度量并分类。结果:实验结果得出灵敏度为0.834 6,特异性为0.962 3,最终大赛综合得分为0.898 5。结论:CCNN使用交叉对比的输入模式扩充数据量,引入信号间的对比信息,同时在神经网络的训练过程中应用统计学思想,使网络具备良好的泛化性,更加适应医学数据量较少的场景,在心音分类中取得较好的结果。  相似文献   
49.
50.
目的 验证呼吸机自动测量的气道阻断压(airway occlusion pressure,P0.1)与标准测量方法的一致性,以及不同触发形式对自动测量结果的影响。方法 选择采用非阻断自动测量P0.1的呼吸机,分别进行模拟肺和临床试验。调节全自动自主呼吸模拟肺,模拟具有不同呼吸努力和呼吸力学特征的48种状态,应用待检测呼吸机,以压力支持通气模式为模拟肺进行通气。临床研究部分纳入15例接受压力支持通气的成年患者。两部分研究均随机交叉应用压力和流量触发,采集呼吸机自动监测的P0.1后,采用标准呼气末气道阻断法进行P0.1测量,作为标准参考值。采用Bland-Altman检验分析P0.1呼吸机监测值与标准参考值的一致性,计算残差(呼吸机监测值-标准参考值)和95%一致性区间,比较不同触发形式对残差的影响。结果 在模拟肺验证中,P0.1呼吸机监测值与标准参考值之间的残差(95%一致性区间)在压力和流量触发下分别为0.04(-0.63~0.70)和-0.54(-1.44~0.36)cmH2O(1 cmH2O=0.098 kPa),两者相比差异具有统计学意义(P<0.001)。临床观察获得了相似的结果,压力和流量触发时的残差(95%一致性区间)分别为-0.11(-0.73~0.52)和-0.54(-1.50~0.59)cmH2O,差异无统计学意义(P>0.05),表明呼吸机监测值与标准参考值间存在一致性。结论 压力触发时,呼吸机非阻断法自动测量的P0.1与标准方法具有良好的一致性。而流量触发明显低估P0.1,建议自动监测时切换到压力触发。  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