玉米淀粉接枝高吸水性树脂的合成研究   总被引：1，自引：0，他引：1  

李雅丽  刘娟 《渭南师范学院学报》2003,18(5):34-35

对影响淀粉—丙烯酸接枝共聚反应的引发剂用量、淀粉／单体比例、聚合温度和聚合时间等因素进行了实验考察，确定了合成玉米淀粉接枝高吸水性树脂的最佳工艺条件。合成了吸水率为400g．g^-1～600g．g^-1的高吸水性树脂．为其工业化生产提供了技术参数。  相似文献   

现代社会和谐的理想：政治正义与个人自由的统一     

梅娟 《江西师范大学学报(哲学社会科学版)》2005,38(6):8-10

现代社会和谐的理想是政治正义和个人自由的美好契合和有机统一。一方面，以人为本，实现个人自由全面的发展是一个公正社会的最后目的。为了公平正义的社会大可不必牺牲个人自由，同时，个人自由可以检验社会公正。另．一方面，作为自由主体的人发出对公共秩序的需求，政治正义能够提供一种普遍公正和持久稳定的生活秩序，满足人们对稳定生活的秩序期待，也就是说政治正义可以约束和范导个人自由。  相似文献   

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   

Assessment of three-dimensional joint kinematics of the upper limb during simulated swimming using wearable inertial-magnetic measurement units     

Silvia Fantozzi  Andrea Giovanardi  Fabrício Anício Magalhães  Rocco Di Michele  Matteo Cortesi  Giorgio Gatta 《Journal of sports sciences》2016,34(11):1073-1080

The analysis of the joint kinematics during swimming plays a fundamental role both in sports conditioning and in clinical contexts. Contrary to the traditional video analysis, wearable inertial-magnetic measurements units (IMMUs) allow to analyse both the underwater and aerial phases of the swimming stroke over the whole length of the swimming pool. Furthermore, the rapid calibration and short data processing required by IMMUs provide coaches and athletes with an immediate feedback on swimming kinematics during training. This study aimed to develop a protocol to assess the three-dimensional kinematics of the upper limbs during swimming using IMMUs. Kinematics were evaluated during simulated dry-land swimming trials performed in the laboratory by eight swimmers. A stereo-photogrammetric system was used as the gold standard. The results showed high coefficient of multiple correlation (CMC) values, with median (first–third quartile) of 0.97 (0.93–0.95) and 0.99 (0.97–0.99) for simulated front-crawl and breaststroke, respectively. Furthermore, the joint angles were estimated with an accuracy increasing from distal to proximal joints, with wrist indices showing median CMC values always higher than 0.90. The present findings represent an important step towards the practical use of technology based on IMMUs for the kinematic analysis of swimming in applied contexts.  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 interval aerobic training combined with strength exercise on body composition,glycaemic and lipid profile and aerobic capacity of obese rats     

Irene Coll-Risco  Virginia A. Aparicio  Elena Nebot  Daniel Camiletti-Moirón  Rosario Martínez  Garyfallia Kapravelou 《Journal of sports sciences》2016,34(15):1452-1460

The purpose of this study was to investigate the effects of interval aerobic training combined with strength exercise in the same training session on body composition, and glycaemic and lipid profile in obese rats. Sixteen lean Zucker rats and sixteen obese Zucker rats were randomly divided into exercise and sedentary subgroups (4 groups, n = 8). Exercise consisted of interval aerobic training combined with strength exercise in the same training session. The animals trained 60 min/day, 5 days/week for 8 weeks. Body composition, lipid and glycaemic profiles and inflammatory markers were assessed.

Results showed that fat mass was reduced in both lean and obese rats following the exercise training (effect size (95% confidence interval (CI)) = 1.8 (0.5–3.0)). Plasma low-density lipoprotein–cholesterol and fasting glucose were lower in the exercise compared to the sedentary groups (d = 2.0 (0.7–3.2) and 1.8 (0.5–3.0), respectively). Plasma insulin was reduced in exercise compared to sedentary groups (d = 2.1 (0.8–3.4)). Some exercise × phenotype interactions showed that the highest decreases in insulin, homeostatic model assessment-insulin resistance, fasting and postprandial glucose were observed in the obese + exercise group (all, P < 0.01). The findings of this study suggest that interval aerobic training combined with strength exercise would improve body composition, and lipid and glycaemic profiles, especially in obese rats.  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