略论休克尔(4n 2)规则与有机物芳香性判别

本文就如何应用休克尔(4n 2)规则,方便、快速、准确地判别稠环、离子和富瓦烯等复杂体系的芳香性、进行了一些探讨,拓宽了休克尔(4n 2)规则的应用范围.     

取熔经意 联藻日月——论《文心雕龙》的《楚辞》批评及其文学史意义

《文心雕龙》有五分之一的篇目谈到了《楚辞》,并设专节讨论屈原。《文心雕龙》深刻论述了《楚辞》的意义和价值,进而从理论上肯定了屈原在中国文学史上的地位;《文心雕龙》全面分析了《诗》、骚之同异,肯定了屈原"自铸伟词"、追求新变的文学史意义;《文心雕龙》还从"诡异之辞"、"触类而长"、因方借巧、"重沓舒状"等方面总结了《楚辞》的审美特质。《文心雕龙》的《楚辞》批评,直观地传达出了刘勰本人进步的文学史观,而且对六朝的文学创作具有实际指导意义。     

电磁波穿过DNG媒质时的传播特性分析

针对广泛关注的DNG媒质(负折射率媒质),以有损耗的Drude型媒质为模型,对电磁波穿过DNG媒质的平行板时的传播特性做了理论分析;采用FDTD方法对正弦电磁波穿过DNG媒质的平行板的传播过程进行了数值建模,数值模拟的结果证明了正弦电磁波在穿过DNG媒质的平行板时仍然具有相速度与群速度方向相反的特性,为DNG媒质的广泛应用提供了理论基础.     

彝族灵魂观透视

彝族灵魂观认为,万物有灵,灵魂不死。人是有灵魂的,人死了以后,灵魂就离开了人的躯体到处游荡,所以要请毕摩(巫师)作祭,悼念死者,给死者的灵魂指路,让他尽快回到祖先的发祥地,同幽冥世界的祖宗在一起,重新劳动生息,接受子孙的祭祀,庇护后人繁荣昌盛。彝族灵魂观具有多元性、游动性、永久性、现实性等特点。     

Effect of Mixed Solvents and Additives on the Habit Modification of 6-APA Crystals

6-aminopenicillanic acid (6-APA) crystals obtained under different physical and chemical conditions of the solutions may present different habits. The habits of diamond-shaped plates are desirable compared with other habits of 6-APA crystals. To obtain ideal 6-APA crystals, the effects of the mixed solvents and additives on 6-APA crystal habits were investigated. Ethanol or acetone was used as the organic solvent, and impurities existing in the ,6-APA purification process were used as the additives. 6-APA growth habits were changed when the concentrations of ethanol, acetone or phenyl acetic acid were increased to exceed their critical concentration. The observed results show that the dominant face on 6-APA crystals was identified to be , {020}, but the overall habit was controlled by the relative growth rates of the : 101 and {002} faces. Crystal growth rates and habits can be appreciably changed by specific adsorption of additives on crystal faces. In some cases solvent molecules can act in a similar way and may be regarded as bulk additives. The effects of additives and organic solvents on 6-APA crystal habits were the results of adsorption effect,which fitted the experimental results quite well.     

Multi-frequency proportional-resonant （MFPR） current controller for PWM VSC under unbalanced supply conditions

This letter presents a multi-frequency proportional-resonant （MFPR） current controller developed for PWM voltage source converter （VSC） under the unbalanced supply voltage conditions. The delta operator is used in place of the shift operator for the implementation of MFPR by using a low-cost fixed-point DSE The experimental results with an alternative control strategy validated the feasibility of the proposed MFPR current controller for the PWM VSC during voltage unbalance.     

Active changes of lignification-related enzymes in pepper response to Glomus intraradices and/or Phytophthora capsici

INTRODUCTION Plants have defense mechanisms against patho-gen infection by inducing systemic resistance in re-sponse to localized pretreatment with biological cotrol agents, thus making them resistant to subsequpathogen infection (Caruso et al., 1999; Hammschmidt, 1999; Mohammadi and Kazemi, 2002; yada et al., 1995; Pozo et al., 2002; Ray et al., 199Biological control of plant pathogens has receivmuch more attention. It is well known that plants amicroorganisms symbiosis is a defense m…     

近期中国风水文化争议综述

近日随着建设部中国建筑文化中心和国际易学联合会主办的“首届中国建筑风水文化与健康地产发展国际论坛”在人民大会堂开幕和以建设部中国建筑文化中心与南京大学易学研究所名义开办的国内首个“建筑风水文化培训班”的开张,什么是风水,风水究竟是科学还是迷信,以及如何看待风水的影响与作用等,又成了学术界争议的热门话题。这一争议热潮有利于人们如何正确认识和对待风水。     

大学英语中个性化教学的探索与实践

个性化教学不是一种学习方式或方法,而是一种教育理念。在每个学生接受传授的同时,以学生为中心,目的是让学生按自己的进度,用自己的方法来学习他们所需要的内容,计算机和网络技术是必要的硬件保证。文章探讨了使用计算机进行个性化教学的利与弊以及如何进行个性化教学。最后,作者以一次教学尝试说明了个性化教学的可行性和效果。     

Influences affecting the soil-water characteristic curve

INTRODUCTION The soil-water characteristic curve (SWCC) gives the relationship between the amount of water in the soil (i.e. gravimetric or volumetric water content) and soil suction (i.e. matric suction at low suction and total suction at high suction). Many properties of a partially saturated soil such as the coefficient of permeability, shear strength and volume strain, pore size distribution, the amount of water contained in the pores at any suction, can be obtained from the SWCC. …