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   350篇
  免费   28篇
  国内免费   41篇
儿科学   44篇
妇产科学   4篇
基础医学   66篇
口腔科学   8篇
临床医学   40篇
内科学   63篇
皮肤病学   3篇
神经病学   7篇
特种医学   53篇
外科学   16篇
综合类   16篇
预防医学   67篇
眼科学   4篇
药学   16篇
中国医学   1篇
肿瘤学   11篇
  2023年   2篇
  2020年   2篇
  2019年   4篇
  2018年   6篇
  2017年   7篇
  2016年   6篇
  2015年   11篇
  2014年   7篇
  2013年   12篇
  2012年   9篇
  2011年   4篇
  2010年   15篇
  2009年   15篇
  2008年   11篇
  2007年   33篇
  2006年   14篇
  2005年   19篇
  2004年   9篇
  2003年   7篇
  2002年   3篇
  2001年   4篇
  2000年   13篇
  1999年   12篇
  1998年   16篇
  1997年   30篇
  1996年   23篇
  1995年   9篇
  1994年   12篇
  1993年   8篇
  1991年   4篇
  1990年   4篇
  1989年   10篇
  1988年   8篇
  1987年   7篇
  1986年   6篇
  1985年   5篇
  1984年   5篇
  1983年   4篇
  1982年   6篇
  1981年   7篇
  1980年   6篇
  1979年   1篇
  1977年   2篇
  1976年   9篇
  1975年   3篇
  1974年   1篇
  1973年   2篇
  1972年   1篇
  1969年   2篇
  1968年   1篇
排序方式: 共有419条查询结果,搜索用时 31 毫秒
31.
OBJECTIVES: This study evaluated the effect of an ergonomic training program on workstation changes and on the prevalence of musculoskeletal disorders among video display unit (VDU) users at a large university. METHODS: A pretest-posttest design with a reference group was used with random allocation of administrative and geographic units. In each group, the measurements involved direct observation of the workstations, a self-administered questionnaire, and a physical examination. The measurements were performed 2 weeks before and 6 months after the training in parallel in both groups. The study population was composed of 627 workers (81% of those eligible). RESULTS: The prevalence of all 3 of the postural stressors evaluated decreased in the experimental group after the training. In the reference group, 2 of the 3 stressors decreased in frequency but to a less extent. Some of these beneficial changes were more frequent in workers under 40 years of age. The prevalence of musculoskeletal disorders decreased among the workers under 40 years of age in the experimental group, from 29% to 13% determined by questionnaire and from 19% to 3% determined by physical examination. In other groups, there was no significant change in the prevalence of musculoskeletal disorders. CONCLUSIONS: Improvements in postural stressors occurred more frequently in the experimental group, and these beneficial changes tended to be more frequent in workers under 40 years of age. Improvements in musculoskeletal disorders occurred in the experimental group among the workers under 40 years of age.  相似文献   
32.
汉语失语症患者动词功能损伤的神经语言学分析   总被引:2,自引:0,他引:2  
目的:分析汉语失语症患者动词功能的损伤和临床病灶部位。方法:于2000-02/04在江苏省徐州市第一、二、三、四医院、解放军第九十七医院等大型医院入住的神经内科患者中选择6位典型的汉语失语症患者作为测查对象。采用北京医科大学汉语失语症成套测验检查法,同时参考波士顿诊断性失语检查法、西方失语症成套测验,并结合头颅CT的检查结果判断失语类型。根据本实验的目的,设计听觉路径和视觉路径两种测试方法。听觉路径通过语音来测试患者的动词功能知识(配价知识);视觉路径则是通过画面来测试患者的动词功能知识。最后,根据被试对测试的正确结果进行统计分析。结果:患者6例均进入结果分析。6例失语症患者的单宾语动词(二价动词)听觉路径成绩为:①字词层级,患者1的正确率为10%,患者2为55%,患者3为75%,患者4为60%,患者5为80%,患者6为35%。②语句层级,患者1的正确率为5%,患者2为40%,患者3为60%,患者4为55%,患者5为65%,患者6为30%。③篇章层级,患者1的正确率为5%,患者2为30%,患者3为50%,患者4为50%,患者5为60%,患者6为25%。6例失语症患者的二价动词视觉路径成绩为:①字词层级,患者1的正确率为15%,患者2为55%,患者3为80%,患者4为65%,患者5为85%,患者6为75%。②语句层级,患者1的正确率为10%,患者2为45%,患者3为65%,患者4为60%,患者5为75%,患者6为65%。③篇章层级,患者1的正确率为5%,患者2为35%,患者3为55%,患者4为50%,患者5为65%,患者6为60%。结论:汉语失语症患者的动词功能中受损伤程度最小的是该动词的基本价位,大脑对任何动词的各种论元结构变换都有极强的适应能力;左额下回后部对动词配价加工起主要作用,还涉及左额下回后部的周围区域和其他较远的相关区域。  相似文献   
33.
学术背景:中医药在防治骨质疏松症方面具有独特优势,但目前关于该病的中药复方用药规律的研究较少,而且多以统计用药频率为主。此法往往需要大样本且须具有典型的概率分布。此外,在中医诊治过程中,个人经验也造成处方配伍用药的偏倚,药物剂量相距甚远,这使药物治疗的安全性和有效性难以保证。目的:应用灰关联分析及信息处理方法探讨治疗骨质疏松症的用药规律。 检索策略:由第一、三、四作者应用计算机检索中国知网1995-01/2005-12期间的相关文献。所用中文检索词包括“骨质疏松,骨萎,中药,治疗”。共检索到169篇文献。纳入标准:①治疗方法为单纯使用中药治疗,不包括其他辅助治疗,如西药、手法、针灸等。②所有中药复方必须药味完整,剂量准确,主治明确,疗效确切。排除标准:排除含有辅助治疗及疗效不确切,药味不全、没有给出药物剂量或剂量不准确的文献。结果选出104篇符合标准的文章。 文献评价:文献的来源主要是通过对治疗骨质疏松症的中药复方的相关文章进行循证医学系统查询,通过灰关联分析及信息处理方法分析查询结果,以此探讨治疗骨质疏松症的中药复方用药规律。资料综合:在治疗骨质疏松症的104首中药复方中共使用106种药物1204频次。其中,使用频次在10次以上的依次为熟地、淫洋藿、杜仲等34味中药,使用总频次为890次,灰关联系数大小依次为山药、淫羊藿、骨碎补等。性温、平,味甘、苦、辛,归肾经、肝经和脾经的药物所占比例较大。在药物分类中,补益药达到23种,占总数的67.6%。其中,又以补阳药为主,其次为补气药。 结论:灰关联分析及信息处理结果认为骨质疏松症的主要病理是脾肾阳虚,其次为气虚、阴虚和血虚,在用药中主要使用补益肝肾、补脾益气、滋阴活血药。  相似文献   
34.
目的:利用核因子κBp65特异性小干涉核糖核酸抑制肿瘤坏死因子α诱导的关节滑膜细胞中一氧化氮合酶2和环氧合酶2的表达,探讨基因治疗类风湿性关节炎的新方法。方法:实验于2005-03/2006-03在北京大学医学部中心实验室(国家级)完成。①实验材料:清洁级健康近交系SD大鼠10只;一氧化氮合酶2,环氧合酶2,3-磷酸甘油醛脱氢酶引物(由北京奥科生物公司合成);肿瘤坏死因子α(Sigma公司);核因子κBp65特异性小干涉核糖核酸和转染条件由北京大学运动医学研究所陈连旭博士提供。②实验干预:切取大鼠髋关节和膝关节的滑膜体外培养滑膜细胞。利用脂质体siPORTTMLipid将核因子κBp65特异性小干涉核糖核酸转染滑膜细胞,再加入肿瘤坏死因子α刺激。阴性对照为任意编码的小干涉核糖核酸,阳性对照为针对3-磷酸甘油醛脱氢酶的小干涉核糖核酸。③实验评估:提取滑膜细胞中的核蛋白,利用电泳迁移率试验检测核因子κB的活性;提取滑膜细胞的核糖核酸和总蛋白,利用反转录聚合酶链反应和蛋白质免疫印记法从信使核糖核酸和蛋白质两水平检测一氧化氮合酶2和环氧合酶2的表达。结果:①肿瘤坏死因子α和核因子κBp65特异性小干涉核糖核酸对核因子κB转录活性的影响:与正常滑膜细胞相比,肿瘤坏死因子α可以显著提高核因子κB的结合能力,而事先转染小干涉核糖核酸48h,再用肿瘤坏死因子α刺激,核因子κB的结合能力又显著降低。②核因子κBp65特异性小干涉核糖核酸对核因子κB下游因子的影响:在培养的滑膜细胞中,肿瘤坏死因子α可以显著增加一氧化氮合酶2和环氧合酶2的表达;在转染小干涉核糖核酸抑制核因子κBp65的表达后再用肿瘤坏死因子α刺激,一氧化氮合酶2和环氧合酶2的表达被抑制。结论:①核因子κBp65特异性小干涉核糖核酸可降低肿瘤坏死因子α诱导的滑膜细胞中核因子κB的转录活性,抑制其下游因子一氧化氮合酶2和环氧合酶2的表达。②核因子κBp65特异性小干涉核糖核酸可用于基因治疗类风湿性关节炎的试验研究。  相似文献   
35.
尼莫地平对烫伤大鼠脑内ZO-1 mRNA及血脑屏障通透性的影响   总被引:2,自引:0,他引:2  
目的:观察尼莫地平对严重烫伤大鼠脑内紧密连接相关蛋白ZO-1mRNA及血脑屏障通透性的影响。方法:实验于2005-04/10在南昌大学基础医学院应用解剖实验室完成。①取健康SD大鼠132只分为正常对照组12只、烫伤组60只,尼莫地平组60只,后两组又设烫伤后1,3,6,12,24h5个时间点,每个时间点12只,其中6只用于脑组织伊文思蓝含量的测定,剩余6只用于ZO-1mRNA的检测。②烫伤组和尼莫地平组大鼠100℃开水烫伤15s,造成背部30%体表总面积Ⅲ度烧伤。尼莫地平组大鼠于烫伤后即刻腹腔注射尼莫地平(0.5mg/kg),其他2组不给药。③各组大鼠于相应的时间点麻醉并处死动物取材,应用化学定量方法检测大鼠脑组织内伊文思蓝含量,运用RT-PCR方法检测大鼠脑内ZO-1mRNA的表达变化。结果:经补充后132只大鼠进入结果分析。①大脑伊文思蓝含量:正常对照组为(10.18±1.79)μg/g,烫伤组伤后1,3,6,12h均高于正常对照组(P<0.05),其高峰在烫伤后6h,为(20.00±0.58)μg/g;尼莫地平组伤后1,6,12h均低于烫伤组(P<0.01),烫伤后6h时为(16.74±0.78)μg/g。②小脑伊文思蓝含量:正常对照组为(12.90±1.32)μg/g,烫伤组伤后1,3,6,12h均高于正常对照组(P<0.05),其高峰在烫伤后6h,为(31.3±1.47)μg/g;尼莫地平组伤后1,3,6,12h均低于烫伤组(P<0.01),烫伤后6h时为(21.05±2.36)μg/g。③脑组织ZO-1mRNA的表达:烫伤组烫伤后3,6,12,24h分别为正常对照组的(0.1235±0.0158),(0.1890±0.0531),(0.2014±0.0412),(0.1555±0.0163)倍(P<0.01);尼莫地平组较烫伤组高,以烫伤后3,6h最为明显,分别为烫伤组的3.96及1.81倍(P<0.01).结论:①严重烫伤后血脑屏障通透性增高,脑内ZO-1mRNA表达下降。②烫伤后早期应用尼莫地平能防止脑内ZO-1mRNA表达下降,并能起到保护血脑屏障功能的作用。  相似文献   
36.
We determined the prevalence of antibody to cytomegalovirus (CMV) in the sera of non-homosexual hemophilia patients and homosexual men infected with the human immunodeficiency virus type 1 (HIV-1). CMV antibody testing by latex agglutination revealed 33 of 58 HIV-1 infected hemophiliacs (57%) were antibody-positive compared with 54 of 54 HIV-1 infected asymptomatic non-hemophiliac homosexuals (100%) (p less than .001). Nine of 15 hemophiliacs (60%) with symptomatic HIV-1 infection were CMV antibody-positive. We also tested 22 HIV-1 antibody-negative hemophiliacs who had received non-heat treated factor concentrates. 14 of these 22 (64%) were CMV antibody-positive compared with 57% of HIV-1 antibody-positive hemophiliacs. We conclude 1) there is little correlation between transmission of HIV-1 and CMV by factor concentrates, 2) the presence of CMV antibody does not appear to be associated with clinical stage of HIV-1 infection in hemophiliacs, and 3) there may be a significant number of CMV antibody-negative hemophiliacs with HIV-1 infection at risk for primary infection and subsequent disease if CMV seronegative blood products are not provided for future transfusions.  相似文献   
37.
38.
Background  Little is known about cross-language measurement equivalence of the job content questionnaire (JCQ) Purpose  The purposes of this study were to assess the extent of cross-language differential item functioning (DIF) of the 27 JCQ items in six languages (French, Dutch, Belgian-French, Belgian-Dutch (Flemish), Italian, and Swedish) from six European research centers and to test whether its effects on the scale-level mean comparisons among the centers were substantial or not. Method  A partial gamma coefficient method was used for statistical DIF analyses where the Flemish JCQ was the reference for other language versions. Additionally, equivalence between the Flemish and Dutch translations was subjected to a judgmental review. Results  On average, 36% to 39% of the total tested items appeared to be cross-language DIF items in the statistical analyses. The judgmental review indicated that half of the DIF items may be associated with translation difference. The impacts of the DIF items on the mean comparisons of the JCQ scales between the centers were non-trivial: underestimated skill discretion (Milan), underestimated decision authority (Leiden), underestimated psychological demands (Milan women), and incomparable coworker support (Gothenburg 95). Conclusion  Cross-language DIF of the JCQ among European countries should be considered in international comparative studies on psychosocial job hazards using JCQ scales.
BongKyoo ChoiEmail:
  相似文献   
39.
Background The role of the single nucleotide polymorphisms (SNPs) on positions 2677G>T/A and 3435C>T of the multi-drug-resistance gene 1 (MDR1) in inflammatory bowel disease (IBD) remains unclear. Aims To further elucidate the potential impact of MDR1 two-locus genotypes on susceptibility to IBD and disease behaviour. Patients and methods Three hundred eighty-eight German IBD patients [244 with Crohn’s disease (CD), 144 with ulcerative colitis (UC)] and 1,005 German healthy controls were genotyped for the two MDR1 SNPs on positions 2677G>T/A and 3435C>T. Genotype–phenotype analysis was performed with respect to disease susceptibility stratified by age at diagnosis as well as disease localisation and behaviour. Results Genotype distribution did not differ between all UC or CD patients and controls. Between UC and CD patients, however, we observed a trend of different distribution of the combined genotypes derived from SNPs 2677 and 3435 (χ2 = 15.997, df = 8, p = 0.054). In subgroup analysis, genotype frequencies between UC patients with early onset of disease and controls showed significant difference for combined positions 2677 and 3435 (χ2 = 16.054, df = 8, p = 0.034 for age at diagnosis ≥25, lower quartile). Herein the rare genotype 2677GG/3435TT was more frequently observed (odds ratio = 7.0, 95% confidence interval 2.5 – 19.7). In this group severe course of disease behaviour depended on the combined MDR1 SNPs (χ2 = 16.101, df = 6, p = 0.017 for age at diagnosis ≥25). No association of MDR1 genotypes with disease subgroups in CD was observed. Conclusions While overall genotype distribution did not differ, combined MDR1 genotypes derived from positions 2677 and 3435 are possibly associated with young age onset of UC and severe course of disease in this patient group.  相似文献   
40.
This study evaluates our institution's target trough cyclosporine (CSA) concentrations as predictors of severe acute graft versus host disease (aGvHD) in children receiving either matched related or unrelated hematopoietic stem cell transplantation (HSCT). The outcomes of 87 consecutive children who underwent allogeneic HSCT and received CSA and methotrexate as prophylaxis against aGvHD between October 1, 1999 and September 30, 2002 were retrospectively evaluated. The proportion of time that each patient maintained a whole blood CSA concentration within or above the initial target range (105-155 ng/mL or 155-210 ng/mL) was calculated for each of the following time periods: in each week after HSCT from day 0 to +28; in the week preceding engraftment; and in the week preceding the onset of aGvHD. Patients were prospectively evaluated twice weekly for the presence and severity of aGvHD by senior attending physicians. The relationship between potential predictors and the development of severe aGvHD was examined using univariate logistic regression. The main variables of interest were the proportion of time that therapeutic or supratherapeutic CSA concentrations were maintained; median CSA concentrations; the number of methotrexate doses received; and the use of folinic acid rescue. Mean follow-up time was 3.0+/-1.9 years among children who survived beyond day +100. Three variables were significantly associated with the development of severe aGvHD on univariate analysis: initial CSA target concentration [odds ratio (OR), 0.24; P=0.03], proportion of time the target CSA concentration was achieved during the second week after transplant (OR, 0.16; P=0.02), and proportion of time the target CSA concentration was achieved during the week before engraftment (OR, 0.22; P=0.0489). Multivariable analysis demonstrated an inverse relationship between the median CSA concentration during the week before engraftment and the development of severe aGvHD (OR, 0.99; P=0.045). These results suggest that achievement of our CSA target concentrations is important to aGvHD outcomes.  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