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   

试论春秋战争中的礼     

赵庆淼 《徐州师范大学学报(哲学社会科学版)》2007,33(6):73-77

礼贯穿于春秋时期战争的整个过程中。其内容主要包括战争过程中的祭祀、占卜、“致师”、“献捷”、“饮至”等制度化环节，某些战争规则以及战争参与者礼仪性的措辞和举止。春秋时期战争中的礼具有明显的过渡性特征：在部分保留西周的形式和精神的条件下逐渐衰落。礼在当时之所以呈现这种特殊的面貌，有其深刻的背景因素：在春秋时期的社会大变革中，社会各阶层力量的重组推动了贵族社会的瓦解，作为贵族宗族组织重要维系的礼制亦随之衰落；但同时，瓦解中的旧秩序和旧意识形态仍对社会成员的思想和行为具奄一定的约束力，  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   

利用三次B样条函数作等值线分析     

姬富强  张环宙 《湖州师范学院学报》1997,(6)

为了解决传统地图等高线、天气图等值线手工分析的缺点,而以计算机自动分析作替代。通过考察插值、拟合几种数学方法,提出如何应用三次B样条函数,处理格点数据,寻找等值控制点,进行曲线拟合,这一方法具有客观化程度高、分析速度快且线条光滑等特点。  相似文献   

基于.NET的设备管理系统的设计与实现   总被引：1，自引：2，他引：1  

韩艳 《兰州石化职业技术学院学报》2008,8(4):42-44

阐述了基于ASP．NET的设备管理系统的设计与实现。系统根据企业的实际需要,利用先进的网络平台,采用B／S体系结构,将数据挖掘技术、网络安全防护技术等结合起来,实现企业设备的智能化管理,极大地提高企业设备的管理水平。  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