储良龙眼挥发性成分的定量- 保留指数分析

基于拓扑理论及MATLAB程序计算41种龙眼挥发性成分的分子连接性指数(mXtv)和电性距离矢量(Mt)。采用最佳变量子集回归方法,建立龙眼挥发性成分的保留指数(BZ)与mXtv、Mt的定量结构-保留相关的五元回归方程,传统判定系数、逐一剔除法交叉验证系数依次为0.981、0.976。用Jackknife法检验模型的稳健性,其传统判定系数在0.975～0.986之间。该模型具有高度稳健性与良好的预测能力,并能较好解释有机组分保留指数的递变规律。     

浅谈客户关系管理在盐业企业中的应用

在目前充满竞争的市场上,如何抓住客户、留住客户,维持客户的忠诚度,保持市场竞争力,是今天所有企业都关心的问题。本文从客户关系管理的基本理论入手。分析盐业企业的管理现状,进一步论述了客户关系管理如何在盐业企业中实施应用。     

油菜AP2／ERF家族转录因子的分离及其生物学功能

油菜的生长发育受病害、干旱、高盐和低温等逆境胁迫的影响较大。油菜植株中很多被上述胁迫诱导而表达的基因,如产物能直接增强油菜对逆境抗性的功能基因,和产物为转录因子而作为信号转导调控其它基因的表达而间接提高抗性的调控基因。很多转录因子涉及到油菜逆境抗性,AP2／ERF是其中重要的一个家族。目前通过不同方法从不同种类的油菜中共克隆了24个AP2／ERF家族转录因子,属于ERF和DREB／CBF亚族。这些基因分别能够被低温、干旱、高盐、乙烯、ABA和茉莉酮酸酯诱导,并启动油菜中一些相关下游基因的表达,从而增强油菜的抗逆性能。本文综述了油菜中AP2／ERF家族转录因子的克隆、进化关系分析、空间结构及生物学功能。     

分布式光纤测温系统分辨率影响因素研究

应用分布式光纤测温系统对船舶电力系统进行在线监测时,由于船舶电缆的特殊运行环境,对测温系统的空间分辨率和温度分辨率提出了更高的要求,而在基于拉曼散射双路解调的分布式光纤测温系统中,系统的空间分辨率、温度分辨率、时间分辨率和测温距离相互制约.为设计满足船舶电力系统在线监测需求的测温系统,分析了系统空间分辨率的影响因素,并...     

油炸过程与油炸食品品质的动态关系研究

本文主要研究了油炸过程中与油炸食品品质变化的动态关系。分析表明油炸食品的水分蒸发速率和吸油率是非线性的，而油炸食品吸油量的多少主要与食品的水分蒸发有关。食品中心的温度不断增加，但不能超过水的沸点；在外皮壳，温度维持在沸点的时间很短，在很薄的外皮壳区域内的温度与油温呈线形关系，外皮壳的厚度随油炸时间的增加而增加。食品在油炸温度为180℃、油料比3：1、油炸时间为2．5min时微观结构状态最好，且在2、5min内食品的断裂力在60—90s时最大。     

马铃薯糖苷生物碱抗真菌活性构效关系研究

采用平板菌丝生长抑制法测定了马铃薯糖苷生物碱茄碱和查茄碱、其酸水解产物β1-查茄碱、β2-查茄碱、γ-查茄碱和β2-茄碱及其硫酸化产物6-O-硫酸查茄碱和6-O-双硫酸茄碱的抗真菌活性,分析了糖链组成和结构与其活性的关系。结果表明,糖链的单糖组成、连接方式、连接顺序和单糖数目等对化合物的生物活性均有重要影响。      

Isolation and Structure-Activity Relationship of the Antioxidant Chemical Constituents from the Flowers of Rosa chinensis Jacq

The objective of this study was to investigate the antioxidant activity, chemical constituents, and structure-activity relationship from the flowers of Rosa chinensis Jacq. The antioxidant activity of the different polar solvent extracts were assayed by a 1,1-diphenyl-2-picrylhydrazyl scavenging experiment. The extract with the strongest 1,1-diphenyl-2-picrylhydrazyl scavenging capacity was further isolated and purified by column chromatography. The structures of the isolated compounds were elucidated on the basis of spectral analysis and physiochemical properties. The antioxidant activity of these compounds was assayed by a 1,1-diphenyl-2-picrylhydrazyl scavenging experiment and ascorbic acid was chosen as the positive control. The ethyl acetate fraction had the strongest 1,1-diphenyl-2-picrylhydrazyl scavenging activity. Ten compounds were obtained, represented as: 3,4,8,9,10-pentahydroxydibenzo[b,d]pyran-6-one (1), quercetin (2), kaempferol (3), 3,5,7,4′-tetrahydroxy-8-methoxy-flavone (4), isoquercetrin (5), kampferol 3-O-β-D-glucoside (6), tiliroside (7), kampferol 3-O-(6′′-galloyl)-β-D-glucoside (8), kampferol 3-O-(2′′,6′′-digalloyl)-β-D-glucoside (9), quercetin 3-O-(2′′,6′′-digalloyl)-β-D-glucoside (10). The 1,1-diphenyl-2-picrylhydrazyl scavenging capacity for these compounds, in descending order, were as follows: 10 > 9 > 1 ≈ 8 > 5 > ascorbic acid ≈ 2 > 6 > 7 > 3 > 4. Compounds 1, 8, 9, and 10 have the stronger antioxidant activity. Our results suggested the antioxidant activities of these compounds might be influenced by the number and position of hydroxyl groups in their aromatic rings.     

A Review on Structure–Activity Relationship of Dietary Polyphenols Inhibiting α-Amylase

The inhibitory effects of dietary polyphenols against α-amylase have attracted great interest among researchers. The aim of this review is to give an overview of the research reports on the structure–activity relationship of polyphenols inhibiting α-amylase. The molecular structures that influence the inhibition are the following: (1) The hydroxylation of flavonoids improved the inhibitory effect on α-amylase; (2) Presence of an unsaturated 2,3-bond in conjugation with a 4-carbonyl group has been associated with stronger inhibition; (3) The glycosylation of flavonoids decreased the inhibitory effect on α-amylase depending on the conjugation site and the class of sugar moiety; (4) The methylation and methoxylation of flavonoids obviously weakened the inhibitory effect; (5) The galloylated catechins have higher inhibition than nongalloylated catechins; the catechol-type catechins were stronger than the pyrogallol-type catechins; the inhibition activities of the catechins with 2,3-trans structure were higher than those of the catechins with 2,3-cis structure; (6) Cyanidin-3-glucoside showed higher inhibition against than cyanidin and cyanidin-3-galactoside and cyanidin-3,5-diglucoside had no inhibitory activity; (7) Ellagitannins with β-galloyl groups at glucose C-1 positions have higher inhibitory effect than the α-galloyl and nongalloyl compounds and the molecular weight of ellagitannins is not an important element.     

织物折皱回复角与其力学性能指标间的关系

为探究较精确、易行的测试和表征织物折皱回复角的方法,首先采用KES-F织物风格仪测试了织物的弯曲、剪切、拉伸和压缩性能,并在KES系统原有力学性能指标基础上引入2个新指标:残余弯曲曲率和残余剪切变形,进而通过数据分析建立了采用织物力学性能指标表示其经、纬向折皱回复角的回归方程;同时分析了织物折皱回复角与各力学性能指标间的相关性.结果表明:回归方程的计算值与折皱回复角的实测值差异不超过0.1°:拉伸功回复率、拉伸比功和弯曲刚度对织物折皱回复性的影响最大,可以通过提高织物的抗拉伸、弯曲和剪切性能及拉伸功回复率来改善织物的抗皱性.