茶中游离氨基酸测定标样的选择

茶中游离氨基酸测定中,国家标准没有对标准样品谷氨酸和茶氨酸加以区别,造成这一指标测定结果的混乱。运用统计学成对比较t检验方法,将2种标样的2个吸光度、按2种标样算出的样品的2种氨基酸含量以及文献中2种标样下游离氨基酸的2种含量分别一一配对,进行样本差数方差分析,结果表明,谷氨酸的吸光度高于茶氨酸,达到极显著水平,且差异随着氨基酸量的增加而增大;样品游离氨基酸含量谷氨酸标样测定结果普遍低于茶氨酸测定结果,差异达到极显著或显著水平。根据茶中各种氨基酸各自的含量和分子量,用加权法计算出混合氨基酸的相对平均分子量为147~150u,与谷氨酸分子量147.1u接近,偏离茶氨酸分子量174.2u;此外,谷氨酸吸光值高,测定更加灵敏。为此,认为茶中游离氨基酸测定的国家标准应该保留谷氨酸做标样,取消茶氨酸作标样。     

徽州臭鳜鱼微生物多样性、品质特性及其酶解产物抗氧化能力分析

研究徽州传统发酵臭鳜鱼的品质特性,运用高通量测序技术对发酵前后鳜鱼微生物群落组成和多样性进行分析,从营养成分、理化性质、质构特性等角度分析发酵品质,并探讨发酵后臭鳜鱼不同酶解产物的抗氧化作用.结果表明,发酵前后鳜鱼的菌群组成差异较大,菌群中优势细菌的种类也各不相同.发酵前鳜鱼中假单胞菌属(Pseudomonas)和肉杆...     

汉语分词索引字数与分词效率的对比研究

针对汉语分词词典中双字哈希索引机制未能充分利用索引分词,而分词效率又明显优于首字哈希索引机制的问题,在充分分析汉语构词特点的基础上,提出了基于三字哈希索引的分词词典机制,并通过将字串的三态标记与下一索引指针的乘积作为哈希值的链地址法,简化了词典结构,节省了内存空间。理论分析和真实语料仿真均证明了三字哈希索引机制与不同字数的其他索引机制相比,具有更好的分词效率。     

黄山贡菊水溶性成分的超声波强化提取工艺研究

利用超声波技术来强化提取黄山贡菊中的水溶性成分,在单因素试验的基础上进行了正交试验,考察了影响水溶性成分提取得率的各因素,通过试验确定超声波强化提取的最佳工艺条件为：温度40℃,超声波浸提时间10min,料液比1g：100ml,提取次数3次,黄山贡菊的水溶性成分提取得率为32.50%。     

大蒜在模拟加工及人体环境条件下杀菌作用研究

文章研究了大蒜在模拟人体内环境(消化环境)和体外加工处理条件下对病原细菌的抗菌活性。方法:滤纸片法。结果表明大蒜在经过模拟人体或加工条件的处理之后,其榨汁对金黄色葡萄球菌、苏云金芽孢杆菌、变形杆菌、大肠杆菌、枯草杆菌与痢疾杆菌等都有比较明显的抑菌效果。     

基于金属作用下抗氧剂对航空润滑油的深色效应

The effect of the xtractsantioxidants 2,6 butylatedhydroxytoluene (AO1) and p,p’ diisooctyldiphenyl amine (AO2) on the hyperchromic of aero lubricating oil (poly α olefin as the base oil) under harmful metal catalysis was investigated. The oil samples were extracted with methanol, acetone and ethyl acetate under the ultrasonic radiation, respectively. The chemical composition of the compounds in the methanol extract was analyzed by FTIR and GC/MS. The color deepening mechanism of oil sample was speculated. The results indicate that metal and antioxidants play the key roles in causing structure change to color deepening of oil. Although the antioxidants could postpone the high temperature oxidation deterioration of the oil, their own structures were easily broken to generate multiple chromophores and auxochrome, such as ketones, amines and quinones, which would lead to the color deepening of oil. The reactions became even more violent with metal catalysis in oil. The compounds of ketones, quinones and amines, including hexanaphthene 2,4 dienone, 1,4 benzoquinone, 2,6 ditertbutyl p benzoquinone, 2,6 ditertbutyl 4 methylene hexanaphthene 2,5 dienone and 4 tertiary butyl 2,6 dimethyl phenyl acetate, 1 (pyridin 3 yl)ethanone, 1 (2,7,7 trimethyl 4,7 dihydrobenzo furan 4 yl)ethanone and other compounds, were believed to deepen the color of oil.     

A Visual Basic program for analyzing oedometer test results and evaluating intergranular void ratio

A visual basic program (POCI) is proposed and explained in order to analyze oedometer test results. Oedometer test results have vital importance from geotechnical point of view, since settlement requirements usually control the design of foundations. The software POCI is developed in order perform the necessary calculations for convential oedometer test. The change of global void ratio and stress-strain characteristics can be observed both numerically and graphically. It enables the users to calculate some parameters such as coefficient of consolidation, compression index, recompression index, and preconsolidation pressure depending on the type and stress history of the soil. Moreover, it adopts the concept of intergranular void ratio which may be important especially in the compression behavior of sandy soils. POCI shows the variation of intergranular void ratio and also enables the users to calculate granular compression index.     

中碱值油酸钙清净剂的合成研究

用油酸和氢氧化钙合成了环保型油酸钙盐清净剂,并对反应条件进行优化。在最佳的工艺条件：碱性物质的加入方式为一次性加入,氢氧化钙与油酸的摩尔比为6∶1,甲醇的加入量6 mL,碳酸化反应温度60℃,二氧化碳通入速率60 mL/min,通入时间50 min,可以获得TBN=274 mgKOH/g的中碱值油酸钙清净剂产品。