共查询到20条相似文献，搜索用时 265 毫秒
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《昭通师范高等专科学校学报》2018,(5):25-28
以猫爪草为原料,主要研究了醇提法对猫爪草中多酚类物质的提取。选取乙醇浓度、料液比、提取时间、提取温度作为考察因素,多酚浸出量为考察指标,探究了猫爪草中多酚的最佳提取工艺。结果表明,猫爪草中多酚类物质的最佳提取工艺为乙醇浓度75%、料液比1:50 (g/mL)、提取时间1.5 h、提取温度70℃。 相似文献
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滁菊叶中黄酮类成分的提取工艺优化 总被引：1，自引：1，他引：0
以溶剂提取法提取滁菊叶中黄酮类成分,以得率为观察指标,考察乙醇浓度、料液比、提取时间等因素对滁菊叶中黄酮类成分提取效果的影响,确定索氏提取滁菊叶中黄酮类成分的工艺优化。结果表明,滁菊叶黄酮类成分最佳提取工艺条件为A：B2C3,即在乙醇浓度80％、料液比1：25、提取时间2．5h滁菊叶中黄酮的得率较高。索氏提取滁菊叶中黄酮,方法简便,有较高的得率。 相似文献
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采用正交实验,考察乙醇浓度（A）、料液比（B）、温度（C）、微波功率（D）4个因素对王不留行中总黄酮提取率的影响.实验得出最佳提取工艺为A1B3C2D3,即溶剂为60%（φ）乙醇,料液比为1∶60,提取温度55℃,微波功率800W.首次运用微波技术从王不留行中提取总黄酮,具有提取率高,提取速率快,提取温度低,能量消耗小等特点. 相似文献
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目的:优化沙棘中总黄酮提取工艺,明确其抗氧化性能。方法:以沙棘为研究对象,以沙棘黄酮得率为指标值,使用乙醇溶液作为提取剂,采用超声波辅助萃取法,对提取时间(A)、提取温度(B)、乙醇体积分数(V乙醇/V_总)(C)、料液比(D)进行单因素试验和响应面分析,考察4个因素对总黄酮得率的影响,并对沙棘黄酮的体外抗氧化活性进行检测。结果:在提取时间23 min、提取温度80℃、50%乙醇、料液比1∶20条件下沙棘黄酮得率最高,为2.316 mg/g。各因素对沙棘黄酮得率的影响大小依次为：料液比、乙醇体积分数、提取时间、提取温度。体外抗氧化结果表明,沙棘黄酮具有很好的DPPH自由基和羟自由基清除能力,当沙棘黄酮粗提取物质量浓度达到5 mg/mL时,沙棘黄酮对DPPH自由基的清除率达87.5%,对羟自由基的清除率达到了77.7%。结论:沙棘中含有丰富的黄酮类物质,且具有较好的抗氧化性能。 相似文献
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《河南职业技术师范学院学报(职业教育版)》2017,(6)
以血红铆钉菇为原料,没食子酸为对照品,总多酚得率为考核指标,研究了血红铆钉菇总多酚的水浴提取工艺条件.在提取温度与时间、乙醇体积分数及液料比等单因素的基础上,通过L16(45)正交试验,确定血红铆钉菇总多酚的最佳工艺条件为:乙醇体积分数75%,液料比30∶1(m L/g),75℃提取120 min.在上述条件下,制备的血红铆钉菇总多酚得率为17.4 mg/g(以没食子酸计). 相似文献
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正交试验法优选毛泡桐中乌索酸提取工艺 总被引：1，自引：0，他引：1
目的:确定毛泡桐中乌索酸的最佳超声提取工艺条件.方法:采用正交设计L9(34)方法,考察乙醇浓度(A)、超声时间(B)、超声功率(C)、料液比(D)对乌索酸提取率的影响,用高效液相色谱法测定含量,并与常规提取法进行了对比.结果:所考察的因素对毛泡桐中乌索酸提取的影响程度为:各因素作用主次顺序为乙醇浓度>料液比>超声时间>超声功率;乌索酸超声提取的最佳条件为:A3B3C2D1,即毛泡桐叶粉末用6倍量95%乙醇超声提取2 h,超声功率为200 W.结论:与常规的提取方法相比,超声提取具有提取时间短、操作简单、提取率高、无需加热等优点.上述方法优选得到的工艺稳定准确、操作简便、方法可行,可用于毛泡桐中乌索酸提取. 相似文献
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以乙醇作为提取溶剂,研究微波法提取川芎中多酚的方法。以乙醇浓度、微波功率、提取时间、料液比4个因素为主要研究对象,通过正交试验分析,得出微波法提取川芎中多酚的最佳条件是：乙醇浓度为80%、微波功率为450w、提取时间为2min、料液比为1：8,此条件下可提取的多酚浓度为1.862mg/g。 相似文献
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李宏 《赤峰学院学报(自然科学版)》2008,(10)
通过正交实验,对苹果渣中苹果多酚的提取工艺条件进行了优化研究,确定最佳工艺条件为:70%乙醇,料液比1:15,提取温度80℃,提取时间2.5h,提取2次,在此最优条件下,苹果多酚得率为4.69g/kg.通过抑制鱼油和葵花子油脂质氧化中过氧化值(PV)、共轭双烯值(CDH)试验表明,苹果多酚具有很强的抗氧化能力. 相似文献
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为优化在超声波辅助条件下脐橙渣中类黄酮的提取条件,在单因素试验的基础上,采用Box-Behnken试验设计和响应面法,研究乙醇浓度、液料比、提取温度对类黄酮得率的影响,建立了各因子与类黄酮得率关系的回归方程.试验结果表明最佳提取条件为:乙醇浓度64%、液料比26 mL/g、提取温度70℃.此条件下类黄酮的得率为3.59%,与预测值3.67%接近. 相似文献
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柿叶中黄酮类物质的提取工艺研究 总被引：1，自引：0，他引：1
为了开发柿叶中黄酮类活性物质的医用价值,弄清提取柿叶中黄酮的影响因素及最佳工艺参数,主要研究了柿叶黄酮的乙醇提取工艺。采用芦丁为对照,利用其铝络合物测定液在510nm处有吸收峰的特点,建立标准曲线,运用吸光光度法测出黄酮类物质的含量;通过单因素试验和正交试验确定了柿叶黄酮类化合物的最佳提取工艺条件。结果表明:用乙醇作为提取溶剂时,影响柿叶中黄酮化合物提取率的因素由大到小依次为:提取时间>提取温度>料液比>乙醇浓度;最佳工艺条件为:提取温度80℃,提取时间40min,乙醇浓度70%,料液比1:35,柿叶黄酮类物质的得率为5.76%。 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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《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
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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. 相似文献
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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. 相似文献
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RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献
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唐芳 《读与写:教育教学刊》2008,5(6)
During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context. 相似文献