In vitro remineralization of hybrid layers using biomimetic analogs     

Hui-ping Lin  Jun Lin  Juan Li  Jing-hong Xu  Christian Mehl 《Journal of Zhejiang University. Science. B》2016,17(11):864-873

Resin-dentin bond degradation is a major cause of restoration failures. The major aim of the current study was to evaluate the impact of a remineralization medium on collagen matrices of hybrid layers of three different adhesive resins using nanotechnology methods. Coronal dentin surfaces were prepared from freshly extracted premolars and bonded to composite resin using three adhesive resins (FluoroBond II, Xeno-III-Bond, and iBond). From each tooth, two central slabs were selected for the study. The slabs used as controls were immersed in a simulated body fluid (SBF). The experimental slabs were immersed in a Portland cement-based remineralization medium that contained two biomimetic analogs (biomineralization medium (BRM)). Eight slabs per group were retrieved after 1, 2, 3, and 4 months, respectively and immersed in Rhodamine B for 24 h. Confocal laser scanning microscopy was used to evaluate the permeability of hybrid layers to Rhodamine B. Data were analyzed by analysis of variance (ANOVA) and Tukey’s honest significant difference (HSD) tests. After four months, all BRM specimens exhibited a significantly smaller fluorescent area than SBF specimens, indicating a remineralization of the hybrid layer (P≤0.05). A clinically applicable biomimetic remineralization delivery system could potentially slow down bond degradation.  相似文献   

虚拟现实系统中人机交互感官机理研究     

阳西述  陈娟 《娄底师专学报》2006,(3):71-72

探讨人机交互机理中感知系统模型和行为系统模型的基本原理与特点，总结出深入研究人机交互机理是实现虚拟现实人机交互的基础。同时指出人机交互感官机理研究有待进一步加强的方面。  相似文献   

Differences in pedalling technique between road cyclists of different competitive levels     

Juan García-López  Sergio Díez-Leal  Ana Ogueta-Alday  Josu Larrazabal  José A. Rodríguez-Marroyo 《Journal of sports sciences》2016,34(17):1619-1626

The purpose of this study was to compare the pedalling technique in road cyclists of different competitive levels. Eleven professional, thirteen elite and fourteen club cyclists were assessed at the beginning of their competition season. Cyclists’ anthropometric characteristics and bike measurements were recorded. Three sets of pedalling (200, 250 and 300 W) on a cycle ergometer that simulated their habitual cycling posture were performed at a constant cadence (~90 rpm), while kinetic and kinematic variables were registered. The results showed no differences on the main anthropometric variables and bike measurements. Professional cyclists obtained higher positive impulse proportion (1.5–3.3% and P < 0.05), mainly due to a lower resistive torque during the upstroke (15.4–28.7% and P < 0.05). They also showed a higher ankle range of movement (ROM, 1.1–4.0° and P < 0.05). Significant correlations (P < 0.05) were found between the cyclists’ body mass and the kinetic variables of pedalling: positive impulse proportion (r = ?0.59 to ?0.61), minimum (r = ?0.59 to ?0.63) and maximum torques (r = 0.35–0.47). In conclusion, professional cyclists had better pedalling technique than elite and club cyclists, because they opted for enhancing pulling force at the recovery phase to sustain the same power output. This technique depended on cycling experience and level of expertise.  相似文献   

Effects of psychosocial variables in the similarity and interdependence of physical activity levels among adolescent best friend dyads     

Vítor P. Lopes  Carl Gabbard  Luis P. Rodrigues 《Journal of sports sciences》2016,34(9):821-828

Given that physical activity (PA) tends to decrease with age during adolescence, addressing factors that affect change is important. This study examined the similarity and interdependence of PA as influenced by psychosocial factors among adolescent best friend dyads. A total of 660 adolescents, representing 330 best friend dyads, completed questionnaires with regard to PA, sitting time, perceived exercise benefits and barriers, physical self-perception and social support for PA. Dyads were also identified as reciprocal and non-reciprocal best friends; reciprocal means that both considered each other best friends and non-reciprocal were those in which only one considered the other a best friend. Data were analysed using a hierarchical linear model framework. Results indicated significant similarities between reciprocal best friend dyads for PA and sitting time, and for sitting time in non-reciprocal best friends (P values <.01). Psychosocial variables were associated with PA in reciprocal best friend dyads and with sitting time in reciprocal and non-reciprocal best friend dyads. Best friend gender, regular sports practice of the person, perceived exercise barriers of the best friend and best friend social support were the best predictors for PA.  相似文献   

浅谈实践环节在教学过程中的重要性   总被引：3，自引：0，他引：3  

黄娟 《高教论坛》2002,(5):83-84

从实践教学和理论教学的特点出发，通过分析两者间的关系，论述了实践教学在教学改革过程中的重要性，并指出教学过程中两者应相辅相成、取长补短。  相似文献   

基于Pro/E的直齿锥齿轮Program参数化造型     

Pei Zhiming) Xu Juan) Lv Huiming) 《石家庄铁路工程职业技术学院学报》2007,(3)

介绍Pro/Engineer的Program参数化造型方法及其程序结构,并且以直齿锥齿轮为实例,详细地介绍Program参数化造型的实现过程。为同类产品实现参数化造型,减少重复劳动,提高设计效率提供一种适用、有效的方法。  相似文献   

由“河堤决口了,洪水冲过来了”说开去     

郑方  李娟 《新乡师范高等专科学校学报》2007,21(3):106-107

复句中的语义关系既是事物之间客观联系的反映,又是人们主观视角的反映。在事物之间的客观联系保持固定的情况下,人们的主观视角会随着认知需求的变化而变化。表现在复句中,则是适时添加复句关系词。并列范畴转化为因果范畴是人的特定视角的转化,这需要一定的客观条件,同时又必须有一定的认知作为前提。  相似文献   

Perceived health problems in swimmers according to the chemical treatment of water in swimming pools     

Álvaro Fernández-Luna  Pablo Burillo  José Luis Felipe  Julio del Corral  Jorge García-Unanue  Leonor Gallardo 《European Journal of Sport Science》2016,16(2):256-265

The objective of this study was to determine which chemical treatment used for disinfecting water in indoor swimming pools had the least impact on users' perceptions of health problems, and which generated the greatest satisfaction with the quality of the water. A survey on satisfaction and perceived health problems was given to 1001 users at 20 indoor swimming pools which used different water treatment methods [chlorine, bromine, ozone, ultraviolet lamps (UV) and salt electrolysis]. The findings suggest that there is a greater probability of perceived health problems, such as eye and skin irritation, respiratory problems and skin dryness, in swimming pools treated with chlorine than in swimming pools using other chemical treatment methods. Pools treated with bromine have similar, although slightly better, results. Other factors, such as age, gender, time of day of use (morning and afternoon) and type of user (competitive and recreational), can also affect the probability of suffering health problems. For all of the above, using combined treatment methods as ozone and UV, or salt electrolysis produces a lower probability of perceived health problems and greater satisfaction.  相似文献   

试论健美操运动对校园体育文化的影响     

屈德新  李宏印  邱娟 《山西广播电视大学学报》2007,12(5):28-29

本文从健美操与校园体育文化两者的功能出发,探讨两者之间的关系。研究表明,健美操作为当代高校一种新兴的校园体育活动,不仅丰富了校园体育文化的内涵,同时对整个校园体育文化的发展方向和结构布局均有着重要的影响。反之,丰富多彩的校园体育文化活动是健美操运动赖以生存和发展的基础,两者相互依赖,相互促进,共同发展。  相似文献   

李清照作品的女性特色     

徐娟 《黑龙江教育学院学报》2007,26(2):93-95

李清照是中国文学史上创造力最强、艺术成就最高的女性作家。综观李清照的作品,不仅题材丰富,其体裁更可谓诗词文赋兼擅,欢愉之作亦工,悲苦之篇尤胜。李清照作品的多姿多采,是其饱尝人间甘苦的人生所决定的。她的词不论是写少女的天真活泼,还是写少妇的相思、幽怨,抑或写老年嫠妇的凄苦境遇,无不表现出一种与众不同的情趣和韵味,令人回味无穷。她词作中所展现的女性情感世界,完美的艺术技巧,充分展示了其个性,揭示了女性生活中婉美、多情的一面,而且以其不同时期的作品,构成了一部女性情感历程的巨著。  相似文献