共查询到20条相似文献，搜索用时 437 毫秒
1.
本研究主要从清除超氧阴离子自由基功能、清除羟自由基功能及抗DPPH自由基能力测试来评价香菇胞外多糖抗氧化功能。在浓度为0.30mg·m L-1条件下,香菇胞外多糖对羟自由基、DDPH自由基的清除率分别为76.23%和62.58%,而如果浓度为0.25mg·mL-1,香菇胞外多糖能将68.12%的超氧阴离子自由基清除。实验结论最终表明,其抗氧化能力比较突出。此外,对香菇胞外多糖的抑菌活性及其抑菌稳定性进行了研究。结果证实:酸碱度值如果处在5-9之间,香菇胞外多糖则全面存在着抑菌活性,其中最强抑菌活性发生在酸碱度值pH=6时。结果证实,该菌株的酸碱抑菌谱比较广。而且这种香菇胞外多糖的热稳定性能较好,121℃条件下30min处理,抑菌活性依然不会受到明显影响。香菇胞外多糖的生化特征良好,有效奠定了其未来的发展与应用基础。 相似文献
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王庆 《安徽科技学院学报》2017,31(2)
目的:研究谷精草多糖最佳提取工艺及其清除DPPH自由基作用。方法:采用超声辅助纤维素酶法并设计L9(34)正交表优选谷精草多糖的提取工艺,对谷精草多糖进行清除DPPH自由基活性测试。结果:优选的工艺条件为纤维素酶浓度3 mg/m L,时间40 min,温度60℃,超声功率400 W,在此工艺条件下,谷精草多糖的提取率可达4.16%。当谷精草多糖浓度为8.0 mg/m L时,对DPPH自由基的清除率可达77.6%,谷精草多糖对DPPH自由基的EC50为0.119 mg/m L。结论:该工艺可用于谷精草多糖的提取,谷精草多糖具有较强的清除DPPH自由基的能力。 相似文献
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以生姜多糖的得率为评价指标,通过单因素试验及正交实验研究生姜多糖的最佳提取工艺。通过邻菲罗啉法、DPPH.法研究评价生姜多糖的体外抗氧化活性。结果表明生姜多糖提取的最佳工艺参数为:液固比20:1、提取温度90℃、/提取时间2.5 h,此工艺条件下生姜多糖的得率为5.82%。生姜多糖对.OH和DPPH.两种自由基均有清除效果,并存在一定的量效关系。当生姜多糖提取液浓度达到1.0 mg/mL时,对.OH和DPPH.的清除率分别可达48%和56%,清除DPPH.的IC50为0.93mg/mL。本试验结果可作为进一步开发利用生姜提供参考。 相似文献
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《安徽科技学院学报》2020,(2)
目的:研究滁菊总黄酮(TFCC)和滁菊多糖(PCC)配伍体内外抗氧化活性。方法:采用回流提取法提取TFCC,大孔树脂进行纯化;采用水提醇沉法提取PCC,savage法进行纯化;测定TFCC和PCC含量,观察TFCC和PCC不同比例配伍对DPPH自由基清除率、羟自由基清除率、ABTS~+·清除率和Fe~(3+)相对还原力的影响,优选TFCC和PCC抗氧化活性最佳配伍比例。将50只老年小鼠随机分为TFCC+PCC组(40 mg/kg+60 mg/kg)、TFCC组(40 mg/kg)、PCC组(60 mg/kg)、维生素E组(200 mg/kg)和正常对照组,采用灌胃方式给药,连续14 d,1次/d,观察TFCC和PCC配伍对老年小鼠血清和肝脏超氧化物歧化酶(SOD)、谷胱甘肽还原酶(GSH-Px)活性及丙二醛(MDA)含量的影响。结果:TFCC含量为722.41 mg/g,PCC含量为626.32 mg/g。TFCC和PCC 2∶3配伍体外抗氧化活性最强,其中DPPH自由基清除率为92.13%,羟自由基清除率为86.76%,ABTS~+·清除率88.23%,Fe~(3+)相对还原力为102.73%。TFCC和PCC配伍能显著升高老年小鼠血清和肝脏SOD、GSH-Px活性,降低MDA水平,且活性明显强于单用TFCC或PCC。结论:TFCC和PCC 2∶3配伍体外抗氧化活性最强,体内实验亦证实该比例配伍抗氧化活性具有协同作用。 相似文献
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麻风树籽初提取物对DPPH·自由基的清除能力研究 总被引：1，自引：0，他引：1
莫绪 《桂林师范高等专科学校学报》2010,24(2):174-175,207
分别以乙醇、石油醚和正己醇为溶剂,采用超声波辅助对麻风树种子籽进行提取,得到Ⅰ、Ⅱ、Ⅲ共3个粗提物,然后采用二苯代苦味酰自由基（DPPH.）法测试了粗提物的清除自由基活性。结果表明：粗提物对DPPH自由基有良好的自由基清除能力,半清除率IC50分别为0.15mg/mL、1.25mg/mL、2.04mg/mL,说明了麻风树籽可作为自由基清除物质资源开发利用。 相似文献
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天然产物抗DPPH自由基活性研究 总被引：3，自引：0，他引：3
采用分光光度法测定山药提取物、牛膝皂苷及山药多糖对DPPH的清除作用，发现山药提取物具有较强的清除DPPH自由基活性，而牛膝皂苷和山药多糖不具备清除DPPH自由基活性. 相似文献
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《常熟理工学院学报》2015,(4)
以苦瓜为原料,水作为提取溶剂,探讨液料比、微波功率和提取时间对苦瓜多糖提取率的影响,在单因素实验基础上,通过正交实验确定苦瓜多糖微波辅助提取最佳工艺,并通过研究苦瓜多糖对羟基自由基、超氧阴离子自由基和DPPH自由基的清除作用探讨其抗氧化活性.结果表明:确定微波辅助提取苦瓜多糖的最佳工艺为:液料比为50:1(m L/g),微波功率60 W,提取时间20 min.在最佳工艺条件下微波辅助提取苦瓜多糖的提取率为10.05%.苦瓜多糖具有较强的清除羟基自由、超氧阴离子自由基和DPPH自由基作用,且随着多糖浓度的增加,清除作用不断增加,具有一定的量效关系.当苦瓜浓度达到2.5 mg/m L时,对羟基自由、超氧阴离子自由基和DPPH自由基的清除率分别达到63.68%、59.24%和42.54%. 相似文献
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以黄花菜为原料,采用水提醇沉法提取黄花菜不同器官中多糖,以苯酚-硫酸法测定多糖质量分数,通过考察多糖对3种自由基清除效果来研究其抗氧化活性。结果显示,花、根、叶中多糖平均质量分数分别为15.27%,24.19%,5.84%,3种多糖对自由基均有一定的清除效果;花多糖对O2-·和·OH的清除效果很显著,清除率分别为92.56%和90.68%;根多糖对O2-·的清除效果也非常显著,清除率为95.62%;叶多糖对3种自由基的清除效果不是很显著,3种多糖对LPO的抑制效果不显著。综上表明,黄花菜的花多糖和根多糖具有很强的抗氧化活性。 相似文献
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以生物电子等排体原理设计合成了2-[[3-羟苯基]亚氨基]苯酚,测试了其清除DP-PH·的活性,并分别探讨了溶剂效应和作用时间这两个因素对其清除DPPH·的影响。结果表明,目标化合物的半清除率浓度IC50小于10mg／mL,说明化合物具有良好的自由基清除活性;溶剂效应对目标化合物清除DPPH·的活性具有重要影响,在DMF中清除DPPH·的活性最优,IC50为408．5μM,在丙酮中的清除活性较差,IC50为868．54μM;目标化合物随作用时间对DPPH·的清除程度有差异,其对DPPH·的清除作用是随时间变化而缓慢进行的。 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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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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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