两种体育课程教学模式对BMI指数异常学生的实验研究

选用不同的体育课程教学模式,对BMI指数异常学生的干预是不尽相同的。其显著性也有所区别。本文旨在引导学生树立正确的健康观,对将来走向社会有着积极的意义。     

差示扫描量热法研究改性双马来酰亚胺的固化过程

用差示扫描量热法(DSC) 研究了CDR-9418 双马来酰亚胺树脂的固化过程, 用动态和静态两种方法分析了其固化反应过程, 发现有两个固化反应放热峰, 并用T-Φ 外推法确定了凝胶温度、固化温度和后固化温度等固化工艺参数。      

Synthesis and thermal properties of bismaleimides with ortho-linked aromatic units

Three bismaleimides (BMIs) each having an ortho-linked aromatic unit were prepared by condensation of maleic anhydride with 1,2-bis(4-aminophenoxy)benzene (1a), 1,2-bis(4-aminophenoxy)-4-tert-butylbenzene (1b), or 2,3-bis(4-aminophenoxy)naphthalene (1c). The molecular structures of these BMIs were confirmed by elemental, IR, and NMR analyses. The thermal behavior of the BMIs was evaluated by differential scanning calorimetry (DSC), and the thermal properties of the thermally cured BMI resins were determined by dynamic thermogravimetric analysis (TGA) and thermomechanical analysis (TMA). The effects of structure of the BMIs on the curing behavior of the BMIs and on the properties of the cured resins were investigated. The BMI of 1a had a relatively high melting point (256 °C) and immediately polymerized after having been melted. The 1b-and 1c-based BMIs with a bulkier molecular structure exhibited lower melting points (136 and 171 °C), facilitating the use of these BMIs in the molten state. The cured BMI resins did not show significant decomposition below 450 °C in air or nitrogen and did not soften below 400 °C.     

Investigation of readily processable thermoplastic‐toughened thermosets: IV. BMIs toughened with hyperbranched polyester

This is the fourth article in a series describing efforts to produce tough, high‐performance thermosets from very low viscosity prepolymers which are autoclave processable. Hydroxy‐terminated hyperbranched polyester (HBP) with a systematically increased molar mass was used to toughen bismaleimide (BMI). HBP was dissolved in the allyl phenol component, B, of a two‐part BMI, to yield homogeneous solutions. The BMI monomer, A, was dissolved in the solution of HBP in B to give homogeneous prepolymers. The fracture toughness (K_Ic) of neat resin plaques was measured by compact tension, while the T_g and storage moduli (E′, at 55 and 200°C) were determined by DMA. At 9% loading, the K_Ic of the BMI increased steadily with HBP molecular weight up to 138% over the control with G5 HBP (M_n ∼ 14,000 g/mol); however, significant decreases in both the T_g and E′ resulted, indicating incomplete phase separation of the thermoplastic. A linear hydroxy‐terminated polyester (M_n ∼ 5400 g/mol) with a repeat unit structure which was similar to the HBP's was prepared and used as a control. The linear polyester (LPE) toughened the BMI nearly as effectively as did the HBP and caused a smaller decrease in the T_g and E′. The viscosity of solutions of HBP and LPE in B were essentially the same at lower loadings in B, but at higher loadings, the HBP viscosity increased faster than did that of the LPE. The viscosity increase was end group‐dependent. Preliminary morphological results are presented to show the effect of the thermoplastic architecture, loading, and end group on the cured thermoset. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1809–1817, 1999     

功能化纳米SiO2-聚醚砜/BMI-酚醛环氧树脂复合材料的固化动力学与性能

以4,4’-二氨基二苯甲烷（DDM）为固化剂、双马来酰亚胺（BMI）和酚醛环氧树脂（F51）为基体、聚醚砜（PES）为增韧剂、硅烷偶联剂KH560功能化纳米SiO₂（KH-SiO₂）为改性剂,采用原位聚合法制备了KH-SiO₂-PES/BMI-F51复合材料,并通过非等温DSC确定了复合材料的固化工艺及固化反应动力学。根据Kissinger方程和Ozawa方程求得体系的表观活化能分别为96.03 kJ/mol和99.18 kJ/mol。FTIR测试结果表明:KH-SiO₂改性效果良好,不饱和双键和环氧基特征峰消失,BMI中C=C双键和F51中环氧基在DDM作用下参与了体系的固化反应。SEM结果表明:PES树脂和KH-SiO₂含量适当时,PES树脂和KH-SiO₂在树脂基体中分散均匀,断裂纹不规则杂乱发展,KH-SiO₂-PES/BMI-F51复合材料呈韧性断裂。力学性能测试和热失重测试表明:当PES含量为4wt%,KH-SiO₂含量为1.5wt%时,KH-SiO₂-PES/BMI-F51复合材料的弯曲强度、弯曲模量和冲击强度分别为156.23 MPa、4.18 GPa和20.89 kJ/m2,较BMI-F51基体分别提高了49.7%、29.4%和82.8%;KH-SiO₂-PES/BMI-F51复合材料的热分解温度为393.1℃,残重率为50%时,分解温度高达523.1℃,耐热性十分优异。KH-SiO₂-PES/BMI-F51复合材料的力学性能和耐热性有了较大提高,为拓展F51及BMI的应用范围提供了一定的理论数据。      

"人机耦合"型H-M系统关键技术——BCI研究

论述了人机一体化系统的概念和三种控制类型,提出大脑计算机接口（Brain—Computer Interface,BCI）是“人机耦合”型H—M系统关键技术。阐述了BCI的研究起源、脑电信号的分析方法、BCI的6种研究方法,BCI系统的硬件构成,对BCI的研究和人机一体化系统和技术的发展具有重要意义。     

双马来酰亚胺树脂基高介电材料的制备及性能研究

采用原位聚合法将石墨和CaCu3Ti4O12(CCTO)与双马来酰亚胺树脂(BMI)、二烯丙基双酚A(BA)复合制备石墨/BMI/BA和CCTO/BA/BMI高介电复合材料。研究了石墨和CCTO含量对复合材料的介电性能的影响,结果表明,石墨含量的增加提高了材料的介电常数和介电损耗,在石墨含量约为11.975%时出现渗流效应,介电损耗增长较大,但最大值仍小于1。CCTO含量的增加也提高了材料的介电常数和介电损耗,材料的介电常数最大时为纯BMI/BA树脂的19倍;而介电损耗较小,最大值小于0.08。     

Give us today our daily bread: The effect of hunger on consumers’ visual attention towards bread and the role of time orientation

This study investigated the effect of hunger on consumers’ visual attention during a food choice task, and the role of time orientation (i.e., present and future orientation) in this interplay. A lab-based eye-tracking experiment including 102 participants was conducted, with hunger as the manipulated factor (hungry, satiated). Participants in the satiated condition were served a breakfast buffet before the experimental tasks, whereas participants in the hungry condition were served the buffet after completion of the tasks. Both groups were exposed to a set of planograms depicting supermarket shelves and were asked to choose an option they could consider buying, while their eye movements were recorded. Stimuli included non-food items as well as the key category of interest, Swedish crisp bread. After completion of the eye-tracking recordings, participants indicated their time orientation as well as their height and weight, which were used to calculate body mass index (BMI). The results revealed that hunger (vs. satiation) increased participants’ present orientation and visual attention towards bread, but decreased their future orientation, with participants’ present orientation mediating the effect of hunger on visual attention. Additional exploratory analyses revealed a positive correlation between participants’ BMI and their present orientation. Taken together, the results offer several fruitful avenues for future research, which may be used to promote public health. Moreover, the findings contribute to the literature by documenting that hungry individuals do not necessarily make more rapid decisions in drive-relevant domains; rather, they may actually devote a larger share of their attentional resources in the food domain, given their desire to acquire food.     

双马来酰亚胺改性氰酸酯的研究进展

双马来酰亚胺树脂(BMI)具有优异的耐热性、电绝缘性、透波性、耐辐射性和阻燃性,并且其力学性能和尺寸稳定性良好;而氰酸酯树脂(CE)具有优异的介电性能。采用BMI改性CE,可实现树脂性能的最佳结合,故对近年来BMI改性CE的研究进展进行了综述。