用高锰酸钾溶液探测维生素C含量的活动设计

北师大版七年级《生物学》第8章“探究食物中的营养成分”一节中有一个“探测食物中的维生素C”活动。关于食物中的维生素C（ Vc）含量,可以用褪色法检测：①Vc可以使高锰酸钾溶液褪色;②可以使碘与淀粉混合液褪色;③可以使吲哚酚褪色。在教材中有各种食品营养成分的含量表,可以让学生查得几种食品中的Vc的含量。例如,土豆100 g含有Vc 16 mg、橘子100 g中含Vc 124 mg等。这些数据是怎样得来的？带着这些问题,笔者设计如下活动。     

维生素C与宝宝的健康(下)

哪些食物富含维生素C所有的水果和蔬菜都含有维生素C。下面有两组食物,第一组食物维生素C含量丰富,第二组食物维生素C含量略微低一些,但仍然是补充维生素C不错的选择。含维生素C丰富的食物:甜椒、柑橘、猕猴桃、西红柿、西兰花、土豆、红薯、哈密瓜、芹菜、     

帮孩子吃掉压力

食疗不仅可以治病,也可以缓解压力,消除疲劳。抗压食物就在您身边,价廉物美,土豆就是一种。土豆中富含维生素C、纤维素和钾。维生素C和维生素B群素有抗压维生素之称。     

果蔬中维生素C测定方法的比较研究

比较研究2,6-二氯靛酚滴定法与铁（Ⅱ）-邻二氮菲分光光度法测定果蔬中维生素C含量。样品处理后,在最佳条件下测定果蔬中的维生素C含量。滴定法在测定深色样品时欠佳;分光光度法适合于深色样品的测定,但操作繁琐。深色的样品宜选择分光光度法测其Vc含量。     

苦菜中维生素C提取条件初探

采用分光光度法对干燥苦菜中维生素C(Vc)提取条件进行了探索.结果表明:叶的Vc含量最高,茎的Vc含量稍高于根的,以乙醇为提取剂时,苦菜中提取Vc的最佳实验温度为30℃,最佳提取时间为40min.甲醇为提取剂时其最佳提取时间为60min.甲醇为最佳的苦菜中提取Vc的提取剂.     

维生素C含量检测实验的改革

为培养学生科学系统的思维方式、提高数据分析能力,对本科生物化学实验教学中"维生素C的含量检测"实验进行改革与创新。在保留传统的2,6-D滴定法基础上,新增了高效液相色谱分析方法的部分内容。采用C18色谱柱,流动相为0.1%草酸,流速为1.0mL/min,进样量为20μL,检测波长为255nm,外标法定量。结果显示:维生素C(Vc)在5~100μg/L内有良好的线性关系(R2=0.999 5),每100g猕猴桃中Vc含量为95.47mg。通过对同一实验多角度开展研究,使学生深入掌握生物化学研究中常用的定性与定量方法,培养学生对数据进行合理的统计与分析能力。     

枣果中维生素C含量的测定及比较研究

本研究为测定和比较新疆和田枣、稷山板枣及酸枣中的维生素C含量,分别采用紫外分光光度法和钼蓝比色法测定新疆和田枣、稷山板枣及酸枣中维生素C的含量,结果表明,紫外分光光度法得到的结果的标准差均小于钼蓝比色法得到的结果,同时回收率也高于钼蓝比色法,因此采用紫外分光光度法测得的结果。新疆和田枣的维生素C含量为18.58mg/100g,稷山板枣的Vc含量10.93mg/100g,酸枣的维生素C含量为70.50mg/100g,各种枣果维生素C含量排列顺序为酸枣〉新疆和田枣〉稷山板枣。     

一个探究性实验教学课题的拓展——果汁饮料中维生素C含量的测定

苏教版高中化学选修教材《实验化学》专题6《物质的定量分析》中有《水果中维生素C含量的测定》的定量分析实验,该实验提供了具体的实验原理与实验过程,要求定量的测定水果中的Vc含量。所以,我们以此为根据进行拓展设计《果汁类饮料中维生素C含量的测定》的探究性实验活动。     

番茄中维生素C的HPLC分析及抗氧化性的测定

采用高效液相色谱法(HPLC)对番茄中维生素C(Vc)含量进行分析.采用流动注射化学发光法,对番茄抗氧化性进行测定,结果表明:番茄能有效地抑制超氧阴离子自由基诱导的鲁米诺化学发光,随着发光体系中番茄含量的升高,发光强度呈下降趋势即具有较强的抗氧化性能;番茄中Vc含量与抗氧化性呈正比例变化.     

食用西红柿有六忌

很多人都喜欢吃西红柿,因为它营养丰富。但西红柿可不能随便吃哦。一、忌与黄瓜同食因为黄瓜中含有一种维生素C分解酶,会破坏其他蔬菜中含的维生素C。西红柿含丰富的维生素C,如果二者一起食用,根本达不到补充维生素C的效果。二、忌与土豆或红薯同食     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

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?     

Western and Eastern culture differences in commercial field

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.     

只要努力,不要后悔

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.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

风的曲线

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.