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.     

Mathematical Analysis of Energy Efficiency in IEEE 802.11 DCF

The standardized IEEE ,802. II distributed coordination function （ DCF） provides a contention-based distributed channel access mechanism for mobile stations to share the wireless medium. However, when stations are mobile or portable units, power consumption becomes a primary issue since terminals are usually battery driven. This paper proposes an analytical model that calculates the energy efficiency of both the basic and the RTS/CTS access mechanisms of the IEEE 802. II protocol. The model is validated with simulation results using NS-2 simulation package. The effects of the network size, the average packet length, the initial contention window and maximum backoff stages on the energy efficiency of both access mechanisms are also investigated. Results show that the basic scheme has low energy efficiency at large packet length and large network size, and depends strongly on the number of stations and the backoff procedure parameters. Conversely, the RTS/CTS mechanism provides higher energy efficiency when the network size is large, and is more robust to variations in the backoff procedure parameters.     

Full time adult credential students’ instructional preferences at California State University,Long Beach: pedagogy or andragogy?

This study investigated the instructional preferences of full time adult credential students after they took a live course called Principles of Adult Education at California State University, Long Beach, (CSULB) in the fall semester of 2002. These full time adult credential students had been working on their adult teaching credentials to meet the competencies specified by the California Commission on Teacher Credentialing. The course introduced students to Andragogy developed by Malcolm Knowles out of the andragogical model, developed by Lindeman (1926). The study used Principles of Adult Learning Scales (PALS), advanced by Gary Conti in 1983 to measure instructional preferences. Data were collected from 30 (100% of 30) full time adult credential students enrolled in a live course to, determine their instructional preferences of helping adults learn. The results of the study showed in most cases these adult learning professionals taught adult students andragogically: in some cases they taught adult students pedagogically.     

有限的概念术语 无限的发展前景——论王希杰先生的"三一"修辞学理论

当代语言学、修辞学大家王希杰先生的“三一”修辞学理论，反愉部修辞学的问题建立在以下三组概念之上：四个世界、零度和偏离、显性和潜性。这个理论体系抽象出了当代修辞学最重要最基本的概念，提高了 修辞学的科学品位和社会功能，因此，可望为21世纪的修辞学研究带来无限广阔的发展前景。     

探讨人民币汇率制度的发展方向

经济全球化和金融自由化推动了金融全球化的迅速发展。金融环境的变车呼唤着我国僵化的人民币汇率由有管理的浮动制度向真正的管理浮动制度转变。尤其进入新世纪，我国在经历了经济制度改革、创新后，经济日新月异，无论从GDP的年增长速度、国际收支状况，还是从金融市场的发展角度看，都具备了汇率制度改进的条件。在充分利用这一改革契机的同时，我们应该意识到经济、金融环境稳定对于一国改革、发展的重要性，认识到改革方式会直接制约改革成铲，所以汇率制度的发展应坚持循序渐进的原则，不宜完全浮动化,而适宜采取汇率目标区的形式，并注重加强亚洲地区的金融合作，增强汇率制度的稳定性。     

体育课堂教学要注重创新教育

根据创新教育理论及学校体育教学的特点，体育教师在课堂教学中应注意培养学生的创新能力，创新是人类社会发展的动力。现代体育课堂教学就是要体现创新，创新教育的根本就是改“应试”教育为全面素质教育。     

China-ASEAN Relations in Higher Education: An Analytical Framework

China’s dramatic economic rise has tended to overshadow other wider perspectives on the developing China and Association of Southeast Asian Nations (ASEAN) relationship, including in higher education. The article examines contemporary relations between China and ASEAN, set against the longer term development of cultural and trade relations. It is argued that, notwithstanding current territorial disputes, and a history of discrimination against ethnic Chinese in several parts of ASEAN, prospects for a deepening of relations in higher education remain strong. Singapore, Malaysia, and Vietnam are selected as three instances of the developing relationship in higher education and some of the links traced, with the former assessed as best placed to take advantage of its China relations in higher education. The developing sense of regionalism is seen as likely to further enhance China-ASEAN relations in higher education.     

一代词宗的落幕悲歌——论《申报·自由谈》刊载的况周颐词作、外传

《申报·自由谈》是中国近现代历时最久、影响最大的文艺副刊。况周颐晚年移居上海,卖文为生,积极挥墨于报刊这种新型媒体,在其生命的最后三年(1924-1926)里,他于《申报.自由谈》上发表词作30余首。这些词作以题画、咏物、酬赠为主,亦庄亦谐,艺术精湛,雅俗共赏,体现出况周颐词的最后辉煌与深远影响。况周颐逝世之后,《申报·自由谈》刊载《况蕙风先生外传》、《况蕙风遗稿》以志纪念,有利于我们深入了解况周颐及当时的世风人情,具有重要的文献价值。     

高职院校开展职业体能教学思考

职业体能教学体现了体育学科体系的高度融合性,在高职院校开设体能课程具有重大意义。高职院校职业体能教学有其自身的特点和发展规律,要把职业体能教学作为一种长效机制进行建设,加大体育设施建设和对教学教改的科研投入,加强对高职院校学生专业和体能特点的研究,制定符合高职院校职业体能的教学大纲,明确课程能力标准,从职业体能的实用性、能力性和职业化角度确立职业体能教学体系。     

试论高校体育教学研究性学习

高校体育教学实施研究性学习是改革教师教学方式和转变学生学习方法的需要,具有实践性、开放性、过程性、问题性、应用性和差异性特点,有一定的实施方法.研究性学习要求体育教师本身具有较强的研究性学习能力,需要教师及时吸纳新知识,更新自身知识结构,更新教育观念,加强研究性学习理念的学习.