共查询到20条相似文献，搜索用时 781 毫秒
1.
建立了一种高效液相色谱测定木瓜中维生素C含量的方法．采用0．1％的草酸作为提取剂,色谱中采用Zorbax SB～C18色谱柱,0．1％草酸水作流动相,流速1．0m/min,紫外检测器检测波长261nm．维生素C在20—100μg／mL内有良好的线性关系,线性回归方程为A=73．0542C＋50．6898,相关系数为0．9998,方法回收率为98．81％～102．45％,相对标准偏差等于0．861％．所用测定方法简便、快速,能准确测定木瓜中维生素C的含量． 相似文献
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分光光度法测定药片中维生素C的含量 总被引：2，自引：0，他引：2
在1mol／L H2SO4介质中，维生素C使高锰酸钾褪色。在525nm处测高锰酸钾的吸光度的变化值△A。△A与维生素C的浓度在0～240μg／mL范围内成线性关系，R=0．9993。用于样品中维生素C的含量测定，回收率在97％～110％之间。 相似文献
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利用维生素C对高锰酸钾的褪色效应建立了褪色光度法测定维生素C的新方法。在1 moL／L H2 SO4介质中,维生素C使高锰酸钾褪色。在波长525 nm处,测定高锰酸钾溶液褪色前后吸光度,吸光度的变化值△A与维生素C的浓度在0～20μg／mL范围内成线性关系,R2＝0.9998。用于样品中维生素C的含量测定,回收率在101％～105％之间,RSD为1.1％。 相似文献
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建立一种用于分析铁观音茶叶和茶茎中维生素C含量的高效液相色谱法.采用超声法提取,以0.01％盐酸做提取剂,对样品中的维生素C含量进行定性和定量分析.线性回归方程为:y=3.286×104 C+3.957×104,相关系数R=0.999 1.维生素C的质量浓度在1.00 ～30.00 μg/mL范围内,峰面积y与浓度C呈良好线性关系.该方法的回收率为90.90％～99.25％,最低检出限1.00 μg/mL.结果表明:铁观音茶叶中维生素C的含量高于茶茎中维生素C的含量. 相似文献
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王永涛 《中学生数理化(高中版)》2011,(4):56-56
题目 维生素C是一种水溶性维生素（其水溶液呈酸性），它的分子式为C6H8O6，人体缺乏这种维生素易得坏血症，所以维生素C又称抗坏血酸．维生素C易被空气中氧气氧化．在新鲜的水果、蔬菜、乳制品中都富含维生素C，如新鲜橙汁中维生素C的含量在500mg／L左右． 相似文献
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维生素C(抗坏血酸)经Cu2+氧化为脱氢抗坏血酸,在一定条件下与邻苯二胺反应生成具有荧光的物质.基于此,建立了一种新的测定维生素C的荧光分析法.实验中对氧化剂Cu2+及邻苯二胺的用量、缓冲液介质等进行了优化,在优化条件下,维生素C的浓度在0.05～5.00 μg/mL与其对应荧光强度呈良好的线性关系,相关系数R2=0.998 7;检出限为0.03 μg/mL;对3个不同浓度的样品进行加标回收实验,其回收率为88.91％ ～92.25％;对1.0μg/mL的样品测定3次,测定结果的相对标准偏差为1.98％.将该法用于西红柿、青椒等水果及蔬菜中维生素C含量的测定,结果令人满意. 相似文献
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测定了野生猴头菌子实体中粗蛋白，粗脂肪、微量元素、维生素及氨基酸等几种主要化学成分，测定结果表明：野生猴头菌中蛋白含量高达5．67％，是目前最畅销食用菌蛋白含量的4倍；粗脂肪含量为3．14％，属于低脂肪菌类；微量无素含量均高于当今市场畅销菌；维生素含量丰富，其中维生素C每百克中含698毫克，远高于一般食用菌． 相似文献
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紫外分光光度法测定果蔬中的维生素C 总被引：21，自引：0，他引：21
李军 《河北职业技术师范学院学报》2000,14(1):41-44
还原型维生素Ｃ在２４３．８ｎｍ下有最大吸收峰,在０～４５０μｇ／ｍＬ范围内具有良好的线性。本研究以Ｃｕ＾２＋作催化剂,利用溶解氧,将在２４３．８ｎｍ处有最大吸收的还原型维生素Ｃ选择性的氧化为２４３．８ｎｍ处无吸收峰的氧化型维生素Ｃ,实现了对样品中各种紫外干扰成分的本底校正,建立了一种测定果蔬中还原型维生素Ｃ的新方法。运用该方法实际测定了草莓、西红柿等样品的还原型维生素Ｃ的含量,回收率在９７．６％～ 相似文献
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蒋新丽 《新课程学习(社会综合)》2014,(11):21-21
适当补充维生素
维生素是人体不可缺少的营养物质,肝功能受损影响维生素的吸收和转运,缺乏维生素又不利于肝病的康复,所以肝病患者要根据症状补充维生素。如乏维生素B,会出现口角炎、舌炎、口腔溃疡等症状,可口服复合维生素B片,一次1片,1日2～3次;缺乏维生素C,会出现倦怠、乏力、没有精神、厌食、面色苍白、轻度贫血、牙龈肿胀等症状,可以口服维生素C片,一次0．5片～1片,一日1次～2次。 相似文献
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罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
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邱崇丙 《唐山师范学院学报》2014,(1):21-23
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。 相似文献
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Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
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Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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陈美曦 《山东教育学院学报》2008,23(2):103-107
Different nations have different social cultures, and the social culture of every nation is developing with the development of the nation, language is greatly influenced by social culture, which enables language to possess national and historical characteristics. Word is the smallest, independent, meaningful linguistic unit of language. It can well reflect the national and historical characteristics. From synchronic aspect, the social and cultural influence on word meaning is mainly embodied in conceptual and associative meanings of word. The incorrespondence of word meaning is a phenomenon that exists in both conceptual and associative meanings of word among different languages. From diachronic aspect, the development of social culture causes some changes of word meaning to some extent. Therefore, social culture plays a key role in vocabulary learning and mastery of a language. 相似文献
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Rachel Zupek 《海外英语》2007,(11):40-41
我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献