溴化[2—(5—己基—1,3—二氧环己烷——2—基)乙基]三乙基铵的合成<英>     

袁先友 《零陵学院学报》1992,(3)

以1—溴己烷,丙二酸二乙酯和丙烯醛为原料,经五步反应首次合成了溴化[2—(5—己基—1,3—二氧环己烧—2—基)乙基]三乙基铵(h).  相似文献   

互联网时代浙江中小企业电子商务应用研究   总被引：2，自引：0，他引：2  

钱栋霖 《丽水学院学报》2008,30(6):11-15

中小企业是浙江经济的重要组成部分,也是开展企业电子商务的重要力量。随着网络的普及,中小企业应用电子商务成为必然趋势。开展电子商务可以为中小企业弥补自身缺陷,提升竞争优势,带来新的发展机遇。采用B2B商业模式、加入BAB电子商务交易市场、实现电子商务与ERP系统的集成是浙江中小企业开展电子商务的重要途径。  相似文献   

卤代硅烷的醇解与应用   总被引：1，自引：0，他引：1  

陈忠云 《邵阳学院学报(社会科学版)》1997,(2)

本文着重讨论了卤代硅烷醇解反应的机理、条件与应用.  相似文献   

Polyethylenimine-cyclodextrin-tegafur conjugate shows anti-cancer activity and a potential for gene delivery     

Hu QD  Fan H  Lou WJ  Wang QQ  Tang GP 《Journal of Zhejiang University. Science. B》2011,12(9):720-729

Polyethylenimine-cyclodextrin-tegafur (PEI-CyD-tegafur) conjugate was synthesized as a novel multifunctional prodrug of tegafur for co-delivery of chemotherapeutic agent tegafur and enhanced green fluorescent protein (EGFP) reporter plasmid DNA. Conjugation of tegafur to PEI-CyD via chemical linkage was characterized by ¹H NMR spectrometry and ultraviolet (UV) spectrometry. PEI-CyD-tegafur was able to condense plasmid DNA into complexes of around 150 nm with positive charge at the N/P ratio of 25, in accordance with electron microscopy observation of compact and monodisperse nanoparticles. The results of in vitro experiments showed enhanced cytotoxicity and considerable transfection efficiency in B16F10 cell line. Therefore, PEI-CyD-tegafur may have great potential as a co-delivery system with anti-cancer activity and potential for gene delivery.  相似文献   

Mixed G<Emphasis Type="Italic">l</Emphasis><Subscript>2</Subscript>/G<Emphasis Type="Italic">H</Emphasis><Subscript>2</Subscript> multi-channel multi-objective control synthesis for discrete time systems     

Wen-jun?YanEmail author  Sen-lin?Zhang 《浙江大学学报(A卷英文版)》2004,5(7):827-834

This paper proposes a new approach for multi-objective robust control. The approach extends the standard generalizedl ₂ (Gl ₂) and generalizedH ₂ (GH ₂) conditions to a set of new linear matrix inequality (LMI) constraints based on a new stability condition. A technique for variable parameterization is introduced to the multi-objective control problem to preserve the linearity of the synthesis variables. Consequently, the multi-channel multi-objective mixed Gl ₂/GH ₂ control problem can be solved less conservatively using computationally tractable algorithms developed in the paper. Project supported by the National Natural Science Foundation of China (No. 60374028), and the Scientific Research Foundation for Returned Overseas Chinese Scholars, Ministry of Education (No. [2004]176)  相似文献   

The happy-fish-little-pond effect on enjoyment: Generalizability across multiple domains and countries     

《Learning and Instruction》2023

Academic enjoyment is an important educational construct given that it benefits students' engagement, persistence, wellbeing, and mental health. In this study, we examine two factors that determine this crucial emotion, namely student- and class-level achievement. Past research has been restricted to single-country or single-domain examinations of secondary school students, limiting generalizability of findings. To bridge this gap, we utilize the Trends in International Mathematics and Science Study and the Progress in International Reading Literacy Study (TIMSS-PIRLS) combined 2011 data (N = 180,084 4th-grade students, 37 countries). Our results provide robust evidence that student-level achievement positively predicts enjoyment in math, science, and reading, while the effects of class-level achievement are negative—the Happy-Fish-Little-Pond Effect. These results showed relative universality across the domains and countries examined.  相似文献   

基于排队论的地铁车站自动售票机配置数量研究     

李华 《成都航空职业技术学院学报》2019,35(2):48-50

自动售票机(TVM)自助售票是地铁车站主要的售票方式,TVM的服务效率直接影响了车站整个票务系统的高效性。以排队系统理论为基础,分析了乘客在TVM上购票时排队系统的基本特征,建立了M1/M2/c排队模型,并通过实例分析了车站在TVM数量配置上的合理性,给出了车站高峰时段及中长期客流增长情况下车站TVM配置建议。  相似文献   

2型糖尿病临床用药的正确选择   总被引：1，自引：0，他引：1  

李春亮  闫爱春  王运东 《河北北方学院学报(医学版)》2005,22(1):42-45

目的:探讨正确合理应用口服降糖药对2型糖尿病(T2DM)患者快速降低血糖(BG),降低T2DM并发症的临床意义.方法:2002.10～2004.10月河北北方学院(原张家口医学院)校医院门诊及住院108例T2DM患者治疗前及治疗5周后进行空腹血糖(FBG)、餐后血糖(PBG),糖化血红蛋白(HbA1c),尿白蛋白(ALB),尿酮体及血脂测定.结果:所有病患治疗5周后各项检测指标均较治疗前有明显改善.结论:正确合理用药对预防或延缓并发症出现有积极的意义.  相似文献   

铂微粒修饰碳纳米管-纳米TiO2/聚苯胺复合膜电极对抗坏血酸的电催化氧化     

陈忠平  陈君华  过家好  褚道葆  尹晓娟  吴何珍 《安徽科技学院学报》2006,20(3):20-23

采用循环伏安法,在含有0.2mol.L-1苯胺的0.5 mol.L-1的硫酸溶液中,以50mv.s-1的扫描速度,在-0.1~0.9V范围内实现苯胺在碳纳米管-纳米TiO2膜电极上的电化学聚合,得到翠绿色的聚苯胺膜,并用交流阻抗谱对复合膜的电化学性质进行了表征。在该电极上修饰铂,制得铂微粒修饰聚苯胺复合膜电极,研究了其对抗坏血酸的电催化氧化,发现修饰后的电极对抗坏血酸的氧化有很高的催化活性。  相似文献   

关于P2P技术的发展与思考   总被引：2，自引：0，他引：2  

宋丽娜 《山东电大学报》2007,(1):33-34

文章先将P2P模式与传统的C/S模式相比较,并论述了P2P技术应用的几个领域、技术分类及其存在的一些问题。  相似文献