The effects of salt concentration on conformational changes in cod (Gadus morhua) proteins during brine salting

The effects of different salt concentrations (6%, 15%, 18% and 24% NaCl (w/w)) on the conformational changes of cod muscle proteins during brine salting were examined in this study. Proteins were extracted from the brine salted samples with solutions of 1 M (5.9%) and 4 M (23.4%) NaCl and the quantity of salt soluble proteins (SSP), disulfide bond (S–S), total sulfhydryl (SH) and available SH content in the soluble fraction were determined. Increased salt concentration in cod muscle promoted protein denaturation and aggregation. The SSP and total SH content decreased, whereas the S–S bond and available SH content increased with increased salt concentration in cod muscle. Disulfide bond formation correlated (r = −0.6) with a decrease in total SH groups. Higher SSP and available SH groups of the samples at lower brine concentrations was explained by smaller concentration gradients and salt diffusion rates, resulting in stronger salting-in at early stages of the brining process. There was a significant difference in conformational changes in proteins extracted with a salt solution of 1 and 4 M, mainly due to a different degree of protein aggregation.     

双循环半群上的群同余

为探讨双循环半群上的同态核,从双循环半群上的同余关系出发,讨论双循环半群关于这类同余的交做成的商群,刻画了这种商群的具体元素,给出双循环半群到整数加法半群的同态映射.结果证明双循环半群上的同态核是最小群同余,且这类特殊同余的交也是最小群同余.     

天然防腐剂壳聚糖的研究与应用

采用圆滤纸片法和平板涂布法测定了壳聚糖－醋酸溶液对细菌和酵母菌的抑菌圈直径和最低抑菌浓度，借此判断壳聚糖－醋酸溶液的抑菌力大小，并选择最佳抑菌浓度用于果蔬保鲜．结果表明：壳聚糖对细菌的抑制力很强，对酵母菌的抑制力较强．使用壳聚糖可延长果蔬保鲜期     

除草剂扑草净的合成

由三聚氯氰出发，经胺化、巯基化和甲基化，合成了除草剂扑草净．总收率达８０．４０％．实验主要对巯基化一步进行了改进．产品用熔点测定、红外和气相色谱法进行了分析，含量达９５．６０％．     

Investigation of the Aroma Profile of Green Tea Leaves Using Organic Synthesis and Conventional Analytical Techniques

Although many aroma components have been identified in green tea leaves, the aroma compounds contributing to green tea＇s characteristic odor have not yet been reported. The authors recently reported that aroma components with a matcha-like odor are present in both green tea and black tea prepared from the Sayamakaori tea cuttivar. This matcha-like odor is similar to the odor of commercial available matcha （high-quality powdered green tea）, and is a specific odor feature of green tea leaves. At present, the green-tea odor is thought to arise from the combination of a large number of constituents. Recent reports indicate that a complex interaction between olfactory receptors and odorants is important for the evaluation of the odors. Taking into consideration these findings, the authors investigated the aroma profile of green tea, focusing on the characteristic molecular structures of the constituents that give matcha-like odor. Using a combination of organic synthesis and gas chromatography-mass spectrometry plus gas chromatography-olfactometry, the authors identified aroma components with matcha-like odors in five other tea cultivars. This investigation also revealed that several compounds with a formyl group were important constituents of the aroma of green tea leaves, although the odor of each constituent was not individually similar to the tea＇s overall aroma. The authors found for the first time a group of key components that have the matcha-like odor.     

壮族布傣族群女子“长袍黑衣”服饰的艺术特征

布傣族群是古骆越人的后裔,属于壮族的一个支系,是中国与越南的跨境民族.“长袍黑衣”是布傣族群女子演奏天琴时所穿着的服饰,地域性特色鲜明,与其他壮族支系有较大的区别;服饰款式与制作工艺独特,具有较强的民族文化内涵和较高的艺术审美价值.通过实地考察调研后,解析了“长袍黑衣”服饰的款式特点及形成原因,阐释了布傣族群的服饰文化...     

寡核苷酸自动合成试剂的研究进展

主要介绍近几年来核酸自动化固相合成试剂的研究进展。     

单片机控制声动同步机械原理示教柜

本教学演示柜由单片机控制各机械模型运动演示,ＶＣＤ机播放语音解说,使教学内容与相应模型的运动演示同步,达到教学自动化,形象直观。文中离控制系统结构及工作原理。     

非均匀颗粒群体沉速试验方法的分析

非均匀颗粒群体沉降现象在自然界相当普遍,本文分析非均匀颗粒群体沉速的试验方法,比较各种沉降试验和流态化试验,得到认识深度取样锥体筒流态化法是目前较好的试验方法。     

小波神经网络结合紫外光谱用于四种维生素混合体系的同时测定

首次实现了小波网络多节点输出,表明该网络在且分混合物的定量分析问题上有独到的优点。运用小波神经网络对Ｂ族维生素的混保体系进行了测定。结果良好。