影响绿茶季节间品质差异的生化因子探析

通过测定同一生态环境下生长的31份茶树材料春、夏、秋3季1芽2叶时茶叶的主要生化成分,同时制作烘青茶样进行感官审评,并对测定数据进行统计分析,以揭示影响绿茶品质季节间差异的主要生化因子。结果表明,有27份材料的茶叶品质呈现出春季高于夏、秋季的变化趋势。对27份材料生化成分与品质总分的逐步回归分析、相关分析和通径分析表明,氨基酸、花青素和叶绿素含量对茶叶品质的影响最大,是导致绿茶品质季节间差异的主要生化因子。其中氨基酸表现为正向影响,在季节间呈现春季高、夏秋季降低的规律;花青素和叶绿素表现为负向影响,在季节间呈现春季低、夏秋季升高的趋势。     

十四种金花茶组植物叶总黄酮含量比较

金花茶叶含有丰富的黄酮类化合物.以70%乙醇为提取溶剂,对14种金花茶叶中的黄酮进行超声波提取,并以芦丁为对照品,采用紫外分光光度法于273 nm处测定吸光度,得出各种金花茶叶总黄酮的含量并进行了比较.结果表明:不同种金花茶叶黄酮的含量差异较大,平果金花茶中新叶的总黄酮含量(22.011%)最高,而东兴金花茶中一年叶龄...     

五指山不同级别新鲜苦丁茶微量元素含量测定

采用火焰原子吸收光谱法对海南五指山苦丁茶不同级别新鲜茶叶中的锌、铁、钙、钾、镁五种元素进行了含量测定,详细地研究了消解酸的种类、HNO3、HCIO4和H2O2的比例、消解酸的体积及消解时间对测定结果的影响。用HNO3-HClO4-H2O2处理样品,测定结果表明不同级别苦丁茶茶叶中均含有丰富的人体必需的微量元素,不同等级的苦丁茶中微量元素含量有差异,但,其含量排序均为KCaMgZnFe,一级苦丁茶中Zn、K、Mg这3种微量元素的含量高于其他等级,而三级苦丁茶中Ca、Fe这2种微量元素含量要高于一、二级的苦丁茶,但总体差别不大。采用此方法回收率为101.38%～103.10%,相对标准偏差小于10%。其方法简便、精密度和灵敏度高,结果令人满意。     

崂山绿茶叶中主要游离氨基酸的组分及含量分析

目的：探析崂山绿茶叶中主要游离氨基酸的组分及含量。方法：依据《茶水浸出物测定》相关标准,采用水浸提法予以完成,采用AccQ·Tag方法对崂山绿茶茶叶当中的氨基酸进行分析。结果：应用崂山绿茶叶茶水样品处理所获得的在具体的游离氨基酸总量与传统相比提升28.6%,在4种茶叶当中主要氨基酸含量呈现出同步增加的状况,所选取的所有经过检测的氨基酸在具体含量上均存在不同程度增加,并且在含量排序方面也基本存在一致性。结论：与直接测定茶汤中的氨基酸相比,崂山绿茶叶茶水样品制备处理虽然操作上较为繁琐,但更能准确反映茶叶中游离氨基酸的含量。因此,可采用茶水样品制备对茶汤直接测定予以代替,使其作为茶水游离氨基酸测定的前处理方法,更能够准确反映崂山绿茶叶中主要游离氨基酸的含量。     

茶叶多糖的糖醛酸含量测定及抗氧化活性研究

采用高效液相色谱法对三个产地茶叶多糖的糖醛酸含量进行了测定,该方法具有操作简便、样品无需预处理等特点,稳定性、重现性较好,回收率高,适合于茶叶多糖糖醛酸含量的测定。结果表明不同产地茶叶多糖的糖醛酸含量有明显差异。本文同时研究了不同产地茶叶多糖对超氧自由基和DPPH自由基的清除作用,以评价其抗氧化活性。结果发现不同产地茶叶多糖的抗氧化活性与其糖醛酸含量呈正相关,糖醛酸含量越高,其抗氧化能力越强。     

几种茶叶生化成分及其抗氧化活性分析

目的：比较白茶与绿茶、红茶生化成分的差异,探讨生化成分与抗氧化活性的关系。方法：以寿眉、安吉白茶及白琳工夫分别为白茶、绿茶、红茶代表,分析茶叶成分,测定茶汤抗氧化活性,并对二者进行相关性分析。结果：总黄酮含量与年份呈正相关关系,而咖啡碱则相对稳定;白茶茶多酚及儿茶素含量均低于绿茶,但其酯型儿茶素所占比重显著高于绿茶,且游离氨基酸、茶氨酸及总黄酮含量也显著高于其他两种茶类;EGC所占比重与酯型儿茶素均与茶汤抗氧化活性有较强的相关性。结论：白茶与其他茶在成分和抗氧化性上均有显著差异;EGCG与抗氧化活性相关性最强。     

茶树黄酮醇苷的合成代谢及检测分析研究进展

黄酮醇及其糖苷类物质是茶叶中含量丰富且具有较好保健功效的一类重要次生代谢物质,不仅可以调节茶树的生理功能,也是茶叶形成独特风味品质的主要贡献物之一。本文综述了国内外黄酮醇及糖苷物质合成代谢的影响因素、途径以及检测方法的研究进展,为更好的了解黄酮醇苷物质的合成规律、探究其在茶树体内的代谢途径以及深度利用黄酮醇苷物质提供支撑。     

ICP光谱结合聚类分析分析茶叶产地的研究

本文采用ICP光谱仪对来自不同产地的25种茶叶中的K、Na、Ca、Mg等共14种元素进行了分析测定。原始光谱经过标准化处理后,结合聚类分析对来自安徽、福建、湖南和雅安四个地区的茶叶进行产地判别。结果表明此法可对不同产地茶叶进行很好的区分,茶叶中矿质元素的含量可作为茶叶产地判别的测量指标之一。     

茶叶中总硒含量及其影响因素的研究

茶叶中硒素总量测定结果表明：土壤含硒量的高低是直接影响茶叶中硒的总量。茶树根、茎、叶、果中均有硒元素,叶片是茶硒积累的主要器官,尤其是老叶,其含量是嫩叶的几倍．茶树品种间含量的差异显著,最大差异达10倍以上．毛茶加工的成品茶含硒量受加工技术措施影响较大,其不同等级的含硒量与级别没有线性关系．     

6种常饮茶咖啡碱含量的差异性研究

本文以常见的6种饮用茶为实验原料,用95%乙醇提取(恒压滴液漏斗)—升华法对其咖啡碱进行提取,并进行含量测定。结果表明:安顺毛峰咖啡碱含量为0.784%,都匀毛尖咖啡碱含量为0.855%;红茶中的滇红的咖啡碱含量为1.143%,英红的咖啡碱含量为1.275%;花茶中的茉莉花茶咖啡碱的含量为0.434%,菊花茶的咖啡碱含量为0.382%。对不同类型的茶叶而言,咖啡碱的含量红茶绿茶花茶。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.