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   199篇
  免费   14篇
  国内免费   25篇
儿科学   5篇
妇产科学   3篇
基础医学   29篇
口腔科学   7篇
临床医学   28篇
内科学   48篇
皮肤病学   12篇
神经病学   3篇
特种医学   2篇
外科学   15篇
综合类   12篇
预防医学   28篇
眼科学   16篇
药学   23篇
肿瘤学   7篇
  2021年   3篇
  2020年   3篇
  2019年   2篇
  2018年   6篇
  2017年   2篇
  2016年   3篇
  2015年   4篇
  2014年   6篇
  2013年   13篇
  2012年   11篇
  2011年   12篇
  2010年   10篇
  2009年   7篇
  2008年   13篇
  2007年   27篇
  2006年   11篇
  2005年   13篇
  2004年   5篇
  2003年   5篇
  2002年   3篇
  2001年   7篇
  2000年   15篇
  1999年   8篇
  1998年   5篇
  1997年   9篇
  1996年   1篇
  1995年   3篇
  1994年   2篇
  1993年   2篇
  1992年   3篇
  1990年   1篇
  1989年   3篇
  1988年   2篇
  1987年   1篇
  1986年   1篇
  1985年   3篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1978年   1篇
  1976年   1篇
  1973年   1篇
  1971年   1篇
  1970年   1篇
  1969年   1篇
  1968年   2篇
  1966年   1篇
  1965年   1篇
排序方式: 共有238条查询结果,搜索用时 31 毫秒
31.
Background Waist circumference (WC), a proxy measure of central body fat, is a better predictor than overall body fat for cardiovascular risk factors in both adults and children. WC cutoffs have been established in many countries, but the national WC reference has not been developed in China. Objective To study the distribution of WC in a representative group of Chinese children for establishing Chinese WC cutoff points. Methods Cross-sectional data obtained from 15 mainland provinces and Hong Kong were collected. There were 160 225 children and adolescents aged 7-18 years old in total. The subjects were divided into five regional groups namely costal city, other city, noah rural, south rural, and Hong Kong, for analyzing the distribution of WC. Results A large variation in WC distribution was found among the five groups for both sexes. Coastal city group had the highest P85 WC values consistently from the early school ages to 18-year-old compared with other groups. In contrast, south rural group had P85 values consistently lagged behind not only the city groups but also the north rural group. Hong Kong group had a high P85 WC at early ages, but because of the smaller increments of WC during adolescence, the P85 curve was gradually exceeded by the north rural groups. Catch-up trend was found in the two rural groups since the peak of puberty. These disparities were caused by not only socioeconomic and urban-rural factors but also north-south differences. Because of the regional variation of WC, a "gradient" prevalence of central obesity was prospected among these groups. Comparisons of WC distributions between the Chinese and the U.S.A or Netherlands demonstrated the necessary of setting up China's own WC cutoffs. Sex and age-specific percentiles were obtained and smoothed by using LMS method. Conclusion The data obtained from this study could be used to develop national WC cutoff points for Chinese children and adolescents.  相似文献   
32.
中国学龄儿童青少年腰围的地区分布和人群特征   总被引:2,自引:1,他引:1       下载免费PDF全文
目的 分析中国儿童青少年代表性人群的腰围分布,为建立标准腰围界值点提供依据.方法 收集内地15省(区、市)和香港地区7~18岁人群横断面调查资料,样本对象共178 865人,划分沿海城市、其他城市、北方乡村、南方乡村和香港地区5个群体,分析各人群腰围分布状况.结果 5个群体人群体格发育水平的差异有统计学意义."沿海城市"群体在7~18岁时腰围第85百分位数(P85)始终高于其他群体.相反,"南方乡村"群体腰围P85不仅低于城市且低于"北方乡村"群体."香港地区"群体在学龄初期腰围水平高,但进入青春期后增长缓慢,腰围P85最终落后于"北方乡村"群体.南、北方乡村群体自青春期开始腰围水平表现为追赶趋势.该差异不仅源自地区社会经济发展水平和城乡差异,也源于南、北方地区差异,预示在使用腰围进行筛查时,超重、肥胖检出率在上述群体中将呈梯层分布趋势.相关分析显示腰围与身高、体重、BMI等体格指标间高度相关.将中国人群腰围分布与美国、荷兰比较,提示有必要建立适合本国人群的腰围筛查界值点,应用LMS法为中国儿童建立性别年龄别腰围百分位数曲线.结论 研究结果将为建立中国儿童人群腰围筛查界值点提供依据.  相似文献   
33.
OBJECTIVE: Bacterial pathogens involved in periodontal diseases exert a part of their destructive effect by triggering and inducing host cells to elevate their secretion of matrix metalloproteinases (MMPs). Pathogen-secreted phospholipase (PLC) is one bacterial product that may trigger this host response. The roles of exogenous PLC leading to the release, secretion and expression of MMPs by peripheral blood neutrophils (PMNs), cultured epithelial cells of human gingiva and porcine periodontal ligament were investigated. Also the activities of PLC in the diseased and healthy gingival sulcular fluid (crevicular fluid, GCF) and molecular forms of gelatin-ases present in dental plaque were investigated. MATERIALS AND METHODS GCF, salivary and dental plaque samples were analyzed for PLC and proteinase activities. The abilities of PLC to induce PMNs and oral epithelial cells to release and express their MMPs were examined by specific functional, immunological and molecular biology means. RESULTS: PMN-derived MMPs were found to predominate in periodontitis GCF and plaque, and PLC activities were higher in GCF of adult periodontitis patients than in healthy controls. Purified bacterial PLC (1 mU ml-I) efficiently induced PMN degranulation. PLC also induced MMP expression in the cultured epithelial cells. The strongest response was seen in MMP-9 and less in MMP-2. The induction was dose-dependent in the range of 0.I-1.0 U ml-1 PI-PLC, and quiescent cultures were more responsive than proliferating ones. PLC induction of MMPs was polar, with increased levels of MMP-9 in the apical region and increased MMP-2 levels secreted in the basal direction. Northern analysis showed a strong increase in mRNA levels of MMP-9 and a smaller increase for MMP-2 and MMP-I. In the second part of the study we investigated the molecular forms of the released MMPs during periodontitis. In bacterial plaque of periodontitis patients the MMP-9 were found to be converted into lower molecular weight forms. Isolated proteinase from Porphyromonas gingivalis (ATCC 33277) was able to convert human proMMPs to their active forms. CONCLUSION: Bacterial PLC may induce degranulation of PMN MMPs and increase MMP expression in oral epithelial cells. The released proteases can be converted into active form by the proteases of plaque bacteria. Thereby, the pathogenic oral bacteria may indirectly participate in the destruction of periodontal tissues.  相似文献   
34.
AIM: To assess functional impairment in terms of visual acuity reduction and visual field defects in inactive ocular toxoplasmosis. METHODS: 61 patients with known ocular toxoplasmosis in a quiescent state were included in this prospective, cross-sectional study. A complete ophthalmic examination, retinal photodocumentation and standard automated perimetry (Octopus perimeter, program G2) were performed. Visual acuity was classified on the basis of the World Health Organization definition of visual impairment and blindness: normal (> or =20/25), mild (20/25 to 20/60), moderate (20/60 to 20/400) and severe (<20/400). Visual field damage was correspondingly graded as mild (mean defect <4 dB), moderate (mean defect 4-12 dB) or severe (mean defect >12 dB). RESULTS: 8 (13%) patients presented with bilateral ocular toxoplasmosis. Thus, a total of 69 eyes was evaluated. Visual field damage was encountered in 65 (94%) eyes, whereas only 28 (41%) eyes had reduced visual acuity, showing perimetric findings to be more sensitive in detecting chorioretinal damage (p<0.001). Correlation with the clinical localisation of chorioretinal scars was better for visual field (in 70% of the instances) than for visual acuity (33%). Moderate to severe functional impairment was registered in 65.2% for visual field, and in 27.5% for visual acuity. CONCLUSION: In its quiescent stage, ocular toxoplasmosis was associated with permanent visual field defects in >94% of the eyes studied. Hence, standard automated perimetry may better reflect the functional damage encountered by ocular toxoplasmosis than visual acuity.  相似文献   
35.
聚乙二醇化干扰素治疗慢性丙型肝炎的研究进展   总被引:1,自引:0,他引:1  
  相似文献   
36.
培养心肌细胞牵张刺激装置的建立及应用   总被引:2,自引:2,他引:2  
1 方法 牵张刺激装置的制作如模式图 1.制作实验模型采用材料为有机玻璃板、2 4孔培养板、硅胶膜 (厚度 0 .2 2 μm) .硅胶膜从平面圆形变为球形时 ,面积扩大的百分比 =(S球 -S园 ) /S园 ,其中S球 =AD2 ,S园 =r2 ,而AD2 =h2 +r2 ,其中r为孔的半径 ,h为膜升高的高度图 2 .通过控制h的大小 ,可控制膜被牵拉的强度 .本实验采用使膜面积扩大 2 0 %的强度 ,故h =4mm[1] .参照Kassiri等[2 ,3 ] 方法进行心肌细胞的分离培养 .生长有贴壁心肌细胞的 2 4孔板被固定于牵张装置 ,缓慢充气使硅胶膜向上凸起 4mm ,分别维持…  相似文献   
37.
Effect of pulley integrity on excursions and work of flexion in healing flexor tendons@Wang YH @Gu YT @Chen F  相似文献   
38.
血、尿中安眠酮及其代谢物的测定   总被引:1,自引:0,他引:1  
刘锋  刘荫棠  冯翠玲  罗毅 《药学学报》1994,29(8):610-616
通过一例安眠酮中毒病人血、尿中安眠酮及其代谢物的测定,描述了用紫外光谱(uv)、气相色谱(GC)和气相色谱质谱(GC/MS)法测定安眠酮及其代谢物的系统分析方法。样品的提取净化采用液一液萃取和固相萃取两种方法,都得到了很好的结果。紫外光谱用于测定血、尿中安眠酮和其代谢物的总量;气相色谱用于测定血、尿中安眠酮原药的含量;气相色谱质谱则用于鉴定血、尿中的安眠酮及其代谢物。除安眠酮外,血、尿中共检出10种安眠酮代谢物,其中包括两种乙酰化代谢物。此法还为临床救治提供指导。  相似文献   
39.

Introduction

To evaluate if interruptions of external beam radiation therapy impact outcomes in men with localized prostate cancer (PCa).

Methods

We included men with localized PCa treated with three‐dimensional conformal radiotherapy (3D‐CRT) or intensity‐modulated radiation therapy (IMRT) of escalated dose (≥74 Gy in 1.8 or 2 Gy fractions) between 1992 and 2013 at an NCI‐designated cancer centre. Men receiving androgen deprivation therapy were excluded. The non‐treatment day ratio (NTDR) was defined as the number of non‐treatment days divided by the total elapsed days of therapy. NTDR was analysed for each National Comprehensive Cancer Network (NCCN) risk group.

Results

There were 1728 men included (839 low‐risk, 776 intermediate‐risk and 113 high‐risk), with a median follow up of 53.5 months (range 12–185.8). The median NTDR was 31% (range 23–71%), translating to approximately 2 breaks (each break represents a missed treatment that will be made up) for 8 weeks of RT with 5 treatments per week. The 75 percentile of NTDR was 33%, translating to approximately 4 breaks, which was used as the cutoff for analysis. There were no significant differences in freedom from biochemical failure, freedom from distant metastasis, cancer specific survival, or overall survival for men with NTDR ≥33% compared to NTDR<33% for each risk group. Multivariable analyses including NTDR, age, race, Gleason score, T stage, and PSA were performed using the proportional hazards regression procedure. NTDR≥33% was not significantly associated with increased hazard ratio for outcomes in each risk group compared to NTDR<33%.

Conclusion

Unintentional treatment breaks during dose escalated external beam radiation therapy for PCa did not cause a significant difference in outcomes, although duration of follow up limits the strength of this conclusion.  相似文献   
40.
Various surgical approaches to pectus excavatum repair concomitant with surgery have been recommended. In this article the authors describe their approach to the problem that they applied in 1989 and onward, successfully, in six consecutive patients. The favorable early and long-term results of these cases illustrate that the simultaneous correction of pectus excavatum and the underlying diseases of the ascending aorta, aortic arch, and the heart can be performed successfully even in emergency situations. The technique recommended provides good cosmetic results and a stable chest wall. It is well applicable in patients of adult age.  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