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   4909篇
  免费   283篇
  国内免费   105篇
耳鼻咽喉   37篇
儿科学   248篇
妇产科学   102篇
基础医学   603篇
口腔科学   159篇
临床医学   416篇
内科学   746篇
皮肤病学   20篇
神经病学   270篇
特种医学   377篇
外科学   690篇
综合类   463篇
预防医学   478篇
眼科学   177篇
药学   290篇
  3篇
中国医学   91篇
肿瘤学   127篇
  2024年   7篇
  2023年   112篇
  2022年   220篇
  2021年   282篇
  2020年   224篇
  2019年   254篇
  2018年   240篇
  2017年   181篇
  2016年   180篇
  2015年   162篇
  2014年   319篇
  2013年   330篇
  2012年   240篇
  2011年   272篇
  2010年   183篇
  2009年   222篇
  2008年   233篇
  2007年   240篇
  2006年   192篇
  2005年   160篇
  2004年   141篇
  2003年   91篇
  2002年   70篇
  2001年   90篇
  2000年   76篇
  1999年   67篇
  1998年   60篇
  1997年   53篇
  1996年   44篇
  1995年   45篇
  1994年   22篇
  1993年   20篇
  1992年   25篇
  1991年   16篇
  1990年   17篇
  1989年   19篇
  1988年   17篇
  1987年   16篇
  1986年   15篇
  1985年   14篇
  1984年   20篇
  1983年   14篇
  1982年   19篇
  1981年   21篇
  1980年   15篇
  1979年   5篇
  1978年   8篇
  1977年   7篇
  1974年   5篇
  1973年   5篇
排序方式: 共有5297条查询结果,搜索用时 15 毫秒
91.
We performed detailed genetic analysis of the VP4/VP2 coding region in human rhinovirus species A to C (HRV-ABC) strains detected in patients with a variety of acute respiratory infections in Kumamoto, Japan in the period 2011–12. The phylogenetic tree and evolutionary timescale were obtained by the Bayesian Markov chain Monte Carlo method. Phylogenetic analyses showed that the present HRV-A, -B, and -C strains belonged to 25, 4, and 18 genotypes, respectively. Some new genotypes were confirmed as prevalent strains of HRV-C. An ancestor of the present HRV-ABCs could be dated back to about 20,000 years ago. The present HRV-A and -C strains have wide genetic divergence (pairwise distance >0.2) with rapid evolutionary rates (around 7 × 10−4 to 4 × 10−3 substitutions/site/year). Over 100 sites were found to be under negative selection, while no positively selected sites were found in the analyzed region. No evidence of recombination events was found in this region of the present strains. Our results indicate that the present HRV strains have rapidly evolved and subsequently diverged over a long period into multiple genotypes.  相似文献   
92.
93.
《Injury》2018,49(6):1149-1154
PurposeADAPT is a fluoroscopic computer-assisted surgery system which intraoperatively shows the distance from the tip of the screw to the surface of the femoral head, tip-to-head-surface distance (TSD), and the tip-apex distance (TAD) advocated by Baumgaertner et al. The study evaluated the accuracy of ADAPT.Patients and methodsA total of 55 patients operated with ADAPT between August 2016 and March 2017 were included as subjects. TSD and TAD were measured postoperatively using computed tomography (CT) and X-rays. The intraclass correlation coefficient (ICC) was checked in advance. The error was defined as the difference between postoperative and intraoperative measurement values of ADAPT. Summary statistics, root mean square errors (RMSEs), and correlations were evaluated.ResultsICC was 0.94 [95% CI: 0.90–0.96] in TSD and 0.99 [95% CI: 0.98–0.99] in TAD. The error was −0.35 mm (−1.83 mm to 1.12 mm) in TSD and +0.63 mm (−5.65 mm to 4.59 mm) in TAD. RMSE was 0.63 mm in TSD and 1.53 mm in TAD. Pearson’s correlation coefficient was 0.79 [95% CI: 0.66–0.87] in TSD and 0.83 [95% CI: 0.72–0.89] in TAD. There were no adverse events with ADAPT use.ConclusionADAPT is highly accurate and useful in guiding surgeons in properly positioning the screws.  相似文献   
94.
95.
在腹腔镜模拟训练过程中,研究不同训练模式下被测试者的注视策略,探索腹腔镜训练的新模式。被测试者被随机分为无指导组,视频学习组和专家指导组进行左右移环任务。利用Tobii X1 Light型眼动仪调用模拟训练箱中的摄像头,采集受试者的眼动数据。通过对数据处理分析,计算注视点个数,平均注视时间,注视时间百分比,扫描距离指标。与对照组相比,视频学习和专家指导模式下,任务完成时间降低23%,扫描距离缩短25%,注视点个数减少17%,平均注视时间没有显著差异。视频组和专家指导组之间无明显差异。结果表明不同学习模式下,被测试者的注视行为有明显差异。视频学习和专家指导下效果更好,可以用专家操作时的注视点视频指导初级训练者进行训练。  相似文献   
96.
背景与目的:乳腺癌手术方式的选择受到诸多因素影响,本研究旨在分析乳腺癌患者选择乳房重建手术的影响因素,重点探讨居住地距离与乳房重建的关系。方法:回顾性分析了1999年1月—2015年12月复旦大学附属肿瘤医院收治的因单侧或双侧0~Ⅱ期乳腺癌行全乳切除术的女性患者临床资料,分析居住地距离与乳房重建比例的关系。结果:非上海患者选择全乳切除术后乳房重建比例高于上海患者(6.1% vs 4.5%,P<0.001)。居住地距离影响乳房重建比例(P=0.035)。单因素分析显示,居住地距离越远,选择乳房重建手术比例越高,而年龄、体质量指数(body mass index,BMI)、TNM分期与乳房重建的选择呈负相关(P均<0.001)。多因素分析显示,年龄增长、BMI增加、TNM分期较晚是拒绝行乳房重建的独立影响因素(P均<0.001),而居住地距离不是乳房重建的独立影响因素(P>0.05),且与具体乳房重建方式无交互作用。年龄与居住地距离呈负相关(P<0.001)。结论:乳腺癌患者的居住地距离与乳房重建比例呈线性相关;年龄、BMI和疾病分期是影响乳房重建的主要因素。  相似文献   
97.
98.
Abstract

Myocardial infarction (MI) is a coronary artery disease acquired due to the lack of blood supply in one or more sections of the myocardium, resulting in necrosis in that region. It has different types based on the region of necrosis. In this paper, a statistical approach for classification of Anteroseptal MI (ASMI) is proposed. The first step of the method involves noise elimination and feature extraction from the Electrocardiogram (ECG) signals, using multi-resolution wavelet analysis and thresholding-based techniques. In the next step a classification scheme is developed using the nearest neighbour classification rule (NN rule). Both temporal and amplitude features relevant for automatic ASMI diagnosis are extracted from four chest leads v1–v4. The distance metric for NN classifier is calculated using both Euclidian distance and Mahalanobis distance. A relative comparison between these two techniques reveals that the later is superior to the former, as evident from the classification accuracy. The proposed method is tested and validated using the PTB diagnostic database. Classification accuracy for Mahalanobis distance and Euclidean distance-based NN rule are 95.14% and 81.83%, respectively.  相似文献   
99.
100.
ObjectiveTo analyze the relationship between nutritional status measured by anthropometry and the mental, psychomotor and language development of infants in marginalized rural areas of Mexico.MethodCross-sectional study with 576 infants aged from 7 to 26 months in four rural locations. Variables consisted of measures of anthropometric and cognitive development.ResultsInfants with short stature had a lower rate of language development, while birth weight was marginally associated with psychomotor development.ConclusionAlthough acute malnutrition (identified by underweight) is no longer a problem in rural areas of Mexico, chronic malnutrition (expressed as stunting) is still common and is associated with alterations in mental development in the child population.  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