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   1082篇
  免费   50篇
  国内免费   47篇
耳鼻咽喉   5篇
儿科学   41篇
妇产科学   11篇
基础医学   120篇
口腔科学   12篇
临床医学   170篇
内科学   258篇
皮肤病学   20篇
神经病学   100篇
特种医学   152篇
外科学   58篇
综合类   26篇
预防医学   55篇
眼科学   10篇
药学   90篇
中国医学   3篇
肿瘤学   48篇
  2023年   4篇
  2022年   2篇
  2021年   7篇
  2020年   6篇
  2019年   5篇
  2018年   13篇
  2017年   16篇
  2016年   14篇
  2015年   30篇
  2014年   20篇
  2013年   32篇
  2012年   27篇
  2011年   27篇
  2010年   50篇
  2009年   34篇
  2008年   42篇
  2007年   70篇
  2006年   44篇
  2005年   32篇
  2004年   36篇
  2003年   15篇
  2002年   31篇
  2001年   27篇
  2000年   18篇
  1999年   23篇
  1998年   48篇
  1997年   51篇
  1996年   56篇
  1995年   34篇
  1994年   33篇
  1993年   21篇
  1992年   11篇
  1991年   16篇
  1990年   18篇
  1989年   38篇
  1988年   37篇
  1987年   27篇
  1986年   26篇
  1985年   25篇
  1984年   20篇
  1983年   8篇
  1982年   17篇
  1981年   11篇
  1980年   14篇
  1979年   7篇
  1978年   5篇
  1977年   6篇
  1976年   6篇
  1975年   10篇
  1973年   2篇
排序方式: 共有1179条查询结果,搜索用时 15 毫秒
21.
背景和目的:最近的研究结果表明,对其他一线药物和注射类药物(如卡那霉素、卷曲霉素)等耐药是影响耐多药结核病(MDR-TB)患者治疗效果的独立危险因素.本研究旨在明确耐其他一线药物和注射类药物对韩国不合并人免疫缺陷病毒(HIV)感染的MDR-TB患者临床疗效的影响.方法:采用回顾性队列研究分析1996年1月至2005年12月首尔国家大学附属医院治疗的211例MDR-TB患者治疗效果,排除7例丢失和7例迁出,对197例患者进行了最终分析.  相似文献   
22.
抛光过程中复合树脂表面粗糙和光泽度的变化   总被引:2,自引:0,他引:2  
目的探讨抛光过程中复合树脂表面粗糙度和光泽度的变化规律。方法测定9种复合树脂抛光前的压接面及经过240目、320目、400目、600目、800目、1200目金刚砂纸抛光后抛光面的粗糙度值和光泽度值。结果随着由粗至细逐级抛光,粗糙度值稳步下降,至800目时均恢复至抛光前的程度;而光泽度值在600目以前变化甚微,800目时骤然回升,至1200目时有5种树脂已达到或超过抛光前的水平。结论复合树脂必须抛光至一定精细程度,才能获得理想的滑泽表面。  相似文献   
23.
目的:蒿甲醚除了具有良好的临床治疗作用外,对正常组织有极大的副作用。实验拟观察蒿甲醚对大鼠肺泡Ⅱ型上皮细胞的影响。方法:实验于2005-09-20/2007-03-10在山东省泰山医学院生命科学研究所、中心实验室和机能实验室完成。①实验材料:蒿甲醚购自昆明制药厂,分析纯,使用前先进行预处理,处理方法:研磨后用溶液配成1g/L的母液,超声助溶解后供实验用。Wistar大鼠70只,体质量(70±15)g,雌雄不拘,由山东大学医学院实验动物中心提供。实验过程中对动物处置符合动物伦理学标准。②实验方法:将大鼠随机分为普通饲料对照组(n=10)和实验组(n=60),实验组分6个亚组,分别在饲料中加入0.1,0.2,0.4,0.8,1.6,3.2mg/kg的蒿甲醚。采用单细胞凝胶电泳技术观察大鼠肺泡Ⅱ型上皮细胞DNA的改变。结果:70只大鼠,饲养过程中实验组死亡6只,死亡原因为饲料添加蒿甲醚造成。当饲料中的蒿甲醚浓度为0.1mg/kg时,大鼠肺泡Ⅱ型上皮细胞DNA损伤率与对照组相比,差异无统计学意义;饲料中的蒿甲醚浓度超过0.2mg/kg时,大鼠肺泡Ⅱ型上皮细胞DNA损伤率明显增加,与对照组相比,差异有统计学意义。且损伤程度与饲料中蒿甲醚含量呈正相关。结论:当饲料中的蒿甲醚浓度超过0.2mg/kg时,蒿甲醚可在一定程度上改变肺泡Ⅱ型上皮细胞的DNA生物学特性。且随着蒿甲醚浓度的升高,这种损害更为明显。  相似文献   
24.
25.
Musculoskeletal disorders in the neck and shoulder area are a major occupational concern in the European countries especially among elderly females. The aim was to assess these disorders based on quantitative EMG indicators and functional tests. 252 female computer users (45–68 years) were recruited from four European countries in two contrast groups: (1) 88 neck/shoulder (NS) cases reporting trouble in the neck and/or shoulder region for more than 30 days during the last year, and (2) 164 NS-controls reporting such trouble for no more than 7 days. Questionnaires, functional/clinical tests, and physiological recordings were performed in workplace related field studies. The results showed no differences in anthropometrics but NS-cases reported more strained head positions and more eye problems than controls. The psychosocial working factors were similar, although, NS-controls had slightly better scores on working conditions, general health, and vitality compared to cases. The NS-cases had lower maximal voluntary contraction (MVC) during shoulder elevation (mean (SD) 310 (122) N) compared to the controls (364 (122) N). During 30% MVC electromyography (EMGrms) in the trapezius muscle was lower in NS-cases (194 (105) μV) than in controls (256 (169) μV), while no differences were found regarding endurance time. Estimated conduction velocity was not different between NS-cases and -controls. Four functional computer tests were performed equally well by NS-cases and -controls, and the corresponding EMG variables also did not differ. A major finding in this large-scale epidemiological study is the significantly lower MVC in NS-cases compared with NS-controls together with lower EMGrms value at 30% MVC, while computer tasks were performed at similar relative muscle activation. The study was unable to reveal quantitative EMG indicators and functional tests that could objectively assess disorders in NS-cases.  相似文献   
26.
Differences in the global methylation pattern, ie hyper‐ as well as hypo‐methylation, are observed in cancers including germ cell tumours (GCTs). Related to their precursor cells, GCT methylation status differs according to histology. We investigated the methylation pattern of normal fetal, infantile, and adult germ cells (n = 103) and GCTs (n = 251) by immunohistochemical staining for 5‐ cytidine. The global methylation pattern of male germ cells changes from hypomethylation to hypermethylation, whereas female germ cells remain unmethylated at all stages. Undifferentiated GCTs (seminomas, intratubular germ cell neoplasia unclassified, and gonadoblastomas) are hypomethylated, whereas more differentiated GCTs (teratomas, yolk sac tumours, and choriocarcinomas) show a higher degree of methylation. Embryonal carcinomas show an intermediate pattern. Resistance to cisplatin was assessed in the seminomatous cell line TCam‐2 before and after demethylation using 5‐azacytidine. Exposure to 5‐azacytidine resulted in decreased resistance to cisplatin. Furthermore, after demethylation, the stem cell markers NANOG and POU5F1 (OCT3/4), as well as the germ cell‐specific marker VASA, showed increased expression. Following treatment with 5‐azacytidine, TCam‐2 cells were analysed using a high‐throughput methylation screen for changes in the methylation sites of 14 000 genes. Among the genes revealing changes, interesting targets were identified: ie demethylation of KLF11, a putative tumour suppressor gene, and hypermethylation of CFLAR, a gene previously described in treatment resistance in GCTs. Copyright © 2010 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.  相似文献   
27.
Yoo E‐H, Woo H, Ki C‐S, Lee HJ, Kim D‐K, Kang I‐S, Park P, Sung K, Lee CS, Chung T‐Y, Moon JR, Han H, Lee S‐T, Kim J‐W. Clinical and genetic analysis of Korean patients with Marfan syndrome: possible ethnic differences in clinical manifestation. Marfan syndrome (MFS) is an autosomal dominant disorder of the fibrous connective tissue caused by mutations in the fibrillin‐1 (FBN1) gene. Although clinical and genetic analyses have been performed in various populations, there have been few studies in Korea. The aim of this study was to investigate the clinical characteristics and genetic background of Korean patients with MFS. In 39 Korean patients with MFS who met the Ghent criteria, the most common clinical finding was aortic dilatation and/or dissection (94.9%), whereas only 35.9% of patients had ectopia lentis. The majority of MFS patients had fewer than four of the skeletal findings required to fulfill the major skeletal Ghent criterion for MFS. Only 21% of Korean patients had major skeletal abnormalities and most cases showed only minor skeletal involvement. FBN1 gene mutations were detected in 35 out of 39 patients (89.7%), which is similar to rates presented in the previous reports. These results suggest that some clinical features in Korean patients with MFS differed from those reported in Western MFS patients.  相似文献   
28.
29.
Working memory capacity has been consistently shown to decline with increasing age. Mechanisms underlying this decline are poorly understood. One index that has been found to predict performance on memory tests is alpha peak frequency, the peak of spectral alpha power of the EEG. Activity in the alpha band has been also associated with higher cognitive functions including attention and anticipation and has been shown to slow with age. Few studies, however, have examined whether there might be a relationship between WM decline and alpha peak frequency. The present study specifically investigated this relationship. Digit span was used as the index of WM function. The study made use of 550 normal subjects aged between 11 and 70 years in the Brain Resource International Database. The data were acquired from six laboratories located in the USA (2), Europe (2) and Australia (2). Forward and reverse digit span were found to be lower in older relative to younger age groups. Spontaneous alpha peak frequency slowed with age and more so at anterior than posterior sites. Frontal alpha peak frequency was found to be a significant predictor of reverse digit span, with each 1 Hz increase in frequency associated with a 0.21 increase in reverse digit span score and this was independent of age, indicating a positive relationship between alpha peak frequency and working memory performance.  相似文献   
30.
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