共查询到20条相似文献，搜索用时 62 毫秒
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超临界CO2萃取当归净油的工艺研究 总被引：3，自引：0，他引：3
采用超临界CO2萃取当归中有效成分当归内酯，研究了萃取压力，萃取温度，以及CO2流量和萃取时间对产品的收率和品质的影响，其最优化工艺条件为：压力20MPa，温度35℃，当CO2流量为20m^3/h时，萃取时间为2小时，在该条件下得到的产品其有效成分当归内酯含量达到89.35%，原料的萃取率达到92.5%。 相似文献
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采用超临界CO2萃取白簕叶中的总黄酮化合物,通过单因素试验和正交试验,研究了超临界萃取条件（压力、温度、时间、CO2流量）对其总黄酮的影响.实验结果表明,最佳提取条件：萃取压力20 MPa,萃取温度35℃,萃取时间1 h,CO2流量20 L/h.白簕叶总黄酮提取值为2.929 mg/g. 相似文献
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研究超临界CO2萃取桂枝中油溶性成分的工艺.以萃取率为指标,考察了萃取压力、萃取温度、分离压力、分离温度、原料粒径等因素对萃取率的影响,并将超临界CO2萃取法与传统的挥发油提取法进行比较.萃取桂枝中挥发油的最佳超临界条件：压力为15 MPa、温度温度为35℃、分离温度为40℃、分离压力为4.2 MPa、萃取时间4 h、原料粒径18目.超临界CO2萃取与传统提取方法相比较：挥发油收率及纯度均高、且安全有效. 相似文献
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应用超临界CO2萃取技术,采用正交实验法,对影响莪术挥发油萃取率大小的萃取压力、萃取温度和CO2流量3个因素进行了研究,最佳工艺为：萃取温度55℃、萃取压力25MPa,CO2流量30L／h,萃取率为8．44％;同时进行了水蒸气蒸馏,挥发油得率为2．31％。并对两种方法提取所得挥发油进行GC—MS成分分析,应用ABTS和FRAP法对两种方法提取莪术挥发组分的抗氧化能力进行了检测及比较,结果显示超临界CO2提取物的成分、得率不同,其抗氧化能力均强于水蒸汽法提取物。 相似文献
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超临界CO2流体夹带丙酮萃取甜瓜籽油的研究 总被引：1，自引：0，他引：1
提出了超临界CO2夹带丙酮萃取甜瓜籽油的方法,研究了不同萃取压力、温度、流量、萃取时间和丙酮含量对甜瓜籽油出油率的影响.对夹带剂及其加入量对萃取效果的影响进行了研究.本研究的结果为下一步综合、无毒、高效地开发利用甜瓜籽莫定了基础. 相似文献
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微波—酶法处理超临界流体萃取黄姜皂素的研究 总被引：1，自引：0，他引：1
应用微波-酶法处理盾叶薯蓣,然后用超临界CO2流体萃取皂素,并用正交试验法考察了萃取温度,萃取压力,萃取时间和夹带剂用量对皂素提取率的影响。研究表明采用微波—酶法处理,有利于萃取操作的进行,提高了萃取效果。正交试验所确定最优工艺条件为:萃取温度60℃,萃取压力32 MPa,萃取时间4 h,夹带用量为20%。 相似文献
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采用正交实验研究广藿香挥发油的提取,得到了每种方法的最佳萃取条件,并比较了多种萃取广藿香挥发油的方法,结果为超临界CO2 萃取比超声辅助萃取和其他萃取方法无论在提取率上还是产品质量上都具有突出的优点,SFE 萃取广藿香挥发油的最佳工艺条件为:萃取压力28MP,萃取时间2h,萃取温度40℃,装料率70%. 相似文献
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橄榄叶中橄榄苦苷不同提取方法的研究 总被引：2，自引：0，他引：2
研究超临界CO2萃取、微波和索氏提取法提取橄榄苦苷的最佳工艺。以HPLC检测橄榄苦苷的含量,采用正交实验,对橄榄叶粒度、提取剂用量、提取时间、超临界萃取压力和萃取温度5个因素进行了考察。结果显示,超临界CO2萃取最佳条件为A1B1C3,微波提取最佳条件为A2B2C1,索氏提取最佳条件为A1B3C1。微波提取3min与超临界CO2萃取2 h、索氏提取6h提取的效果相当,微波提取时间短,操作简便,适用于工业化生产。 相似文献
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王华芳 《三门峡职业技术学院学报》2015,(2):132-136
以杜仲叶为原料,研究了超临界CO2萃取杜仲叶总黄酮的工艺条件,并以总黄酮提取率为指标,通过设计L9(33)正交试验研究了萃取温度、压强和时间对超临界CO2萃取杜仲叶总黄酮的影响。结果表明:三因素对提取率的影响顺序为压强>温度>时间,最佳提取工艺条件为温度50℃,压强30MPa,时间120min。同时按照最佳工艺参数进行验证提取,提取率高达10.55%。 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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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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《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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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