中药合欢甙提取工艺的优选

用热浸法和回流提取法,以合欢甙含量为指标,考察提取溶剂、溶媒用量、提取次数、提取时间和浸泡时间对有效成分提取率的影响,优选中药材合欢花中合欢甙的提取工艺;实验结果表明:加25倍量95%乙醇,浸泡1h,回流提取2次,每次1h,提取率为28.9%是最合理提取工艺,该提取工艺为合欢甙提取工艺的改进提供一定的参考.     

3D thermoelasticity solutions for functionally graded thick plates

Thermal-mechanical behavior of functionally graded thick plates, with one pair of opposite edges simply supported, is investigated based on 3D thermoelasticity. As for the arbitrary boundary conditions, a semi-analytical solution is presented via a hybrid approach combining the state space method and the technique of differential quadrature. The temperature field in the plate is determined according to the steady-state 3D thermal conduction. The Mori-Tanaka method with a power-law volume fraction profile is used to predict the effective material properties including the bulk and shear moduli, while the effective coefficient of thermal expansion and the thermal conductivity are estimated using other micromechanics-based models. To facilitate the implementation of state space analysis through the thickness direction, the approximate laminate model is employed to reduce the inhomogeneous plate into a homogeneous laminate that delivers a state equation with constant coefficients. The present solutions are validated by comparisons with the exact ones for both thin and thick plates. Effects of gradient indices, volume fraction of ceramics, and boundary conditions on the thermomechanical behavior of functionally graded plates are discussed.     

芯片键合层材料对功率型LED热阻的影响

分析了功率型LED热阻系统的构成,通过Flotherm软件对不同材料的芯片键合层的功率型LED进行热分析,结果表明,芯片键合层材料的导热系数越大,器件的热阻越小,散热性能越好,选用芯片键合材料对功率LED器件的热性能有着重大的影响。     

Theoretical and experimental studies of heat transfer with moving phase-change interface in freezing and thawing of porous potting soil

Soil in a cold region is subject to frequent freezing and thawing cycles. Soil frozen for a prolonged period may cause adverse freeze damage to the plants due to cell dehydration or root cell rupture. It is important to understand the detailed heat transfer behaviors of the freezing and thawing processes to prevent freeze damage, and to devise proper mitigation measures for effective pot planting in cold regions. A theoretical model was developed to analyze the transient moving phase-change interface heat transfer in the freezing and thawing of porous potting soil. The theoretical derivation is based on the assumption that the soil freezes completely at a single temperature. Microscopic poromechanic effects on heat transfer behavior were ignored. The spatial domain of the problem was simplified to a 1 D spherical coordinate system with variation in the radial direction. Green＇s function was applied to solve for the time-dependent body temperature. Experiments were conducted for validation of the theoretical model Reasonable agreement between the theoretical predictions and experimental measurements was obtained. The theoretical model developed can be easily used to determine the sensitivity of various parameters in the freezing/thawing processes, e.g., thermal properties of soil, ambient temperature, and planting pot size.     

李渔戏曲词采论的美学意义

李渔非常重视戏曲的唱词的通俗化和机趣性。他在《闲情偶寄·词采第二》一章中专门讨论了曲文的词采问题,提出了“贵显浅”、“重机趣”、“戒浮泛”、“忌填塞”四款。李渔戏曲的词采具有深刻的美学意义,它集中表现为意深词浅的通俗美和机趣尖新的形象美。     

特色校园文化：一所学校成熟的标志

[策划人语]毫无疑问,“文化热”已经成为我们时代的重要特征。教育,塑造文化,又源于文化。教育与文化,有着异常亲密的关系。一所学校没有文化,是难以想象的;一所学校没有自己的特色文化,又是不成熟的。今年夏初,我们曾以“特色校园文化的构建”为题,在毛主席故里韶山开展了一次校长论坛。     

小学奥数热的冷思考

小学奥数热现象出现的最根本原因是对优质教育资源的追求,直接原因是当前的择校机制.此外,奥数经济也起到一定的推波助澜作用.奥数热折射出当前教育中的功利主义倾向,不利于教育公平,在很大程度上加重了学生的负担.展望未来,奥数教育应该抛弃功利化,回归它本身.     

嗜热细菌噬菌体的研究进展

嗜热细菌噬菌体是一类寄生在嗜热细菌中的病毒,其在自然界和人类社会中发挥着重要的作用,但是目前对嗜热噬菌体的研究尚处于起步阶段。就国内外对嗜热细菌噬菌体的研究状况进行系统介绍。     

我国煤矿瓦斯抽采技术现状与发展前景

瓦斯是煤矿由事故源到清洁能源的转变,现在煤矿的瓦斯较好地服务于当地经济.我国煤矿瓦斯抽采理念的发展先后经历的“局部防突措施为主、先抽后采、抽采达标和区域防突措施先行”四个阶段到瓦斯抽采技术发展的四阶段;论证了五种主要的瓦斯抽采技术以及瓦斯抽采技术装备;论述了瓦斯抽采后的消突评价;最后展示了未来瓦斯抽采的技术发展方向.     

沥青路面厂拌热再生技术研究

本文首先针对废旧沥青混合料的利用现状,说明了研究旧沥青混合料再生技术的重要性;其次,通过几种再生技术的比较,重点突出厂拌热再生的适用性;最后,具体阐述了厂拌热再生的再生原理.