淫羊藿苷与脱水淫羊藿素的体外抗氧化研究

为研究淫羊藿苷和脱水淫羊藿素的体外抗氧化活性,分别测定了两者对1,1-二苯基-2-苦苯肼自由基(DPPH.)、超氧阴离子自由基(O2.)、羟自由基(OH.)的清除能力、对脂质过氧化的抑制能力、还原力以及总抗氧化能力.实验结果表明,淫羊藿苷具有很强的清除DPPH.、超氧阴离子自由基,还原力和总抗氧化的能力,有较强的清除OH.的能力,且均呈剂量依赖性.脱水淫羊藿素对DPPH.的清除能力很强,对OH.、超氧阴离子和脂质过氧化有较强的清除和抑制作用,表明淫羊藿苷和脱水淫羊藿素具有明显的抗氧化活性.     

脱脂沙苑子乙醇提取物的体外抗氧化活性研究

通过测定脱脂沙苑子乙醇提取物(ESA)对1,1-二苯基-2-苦苯肼自由基(DPPH·)、超氧阴离子自由基(O-·2)和羟基自由基(·OH)的清除能力、对Fe2 诱导的脂质过氧化反应的抑制作用、还原力和总抗氧化力,评价ESA的体外抗氧化活性,并与公认的抗氧化剂维生素C作了对照.结果表明,ESA有一定的DPPH·清除能力(IC50=419.1μg/mL)、较强的超氧阴离子清除能力(IC50=117.9μg/mL)和羟基自由基清除能力(IC50=224.4μg/mL),能有效的抑制脂质过氧化(IC50=1.70 mg/mL),有良好的总抗氧化力,说明沙苑子具有明显的抗氧化活性.     

土家药食资源藤茶提取物体外抗氧化活性研究

系统探讨民族药藤茶的体外抗氧化活性,为藤茶的进一步产业开发与资源利用提供科学依据.分别采用DPPH自由基清除法、羟基自由基清除法、超氧阴离子清除法,以及FRAP法检测总抗氧化能力共4种体外抗氧化活性实验,系统观察藤茶对不同自由基的抗氧化活性.结果显示,藤茶提取物对DPPH自由基、羟基自由基以及超氧阴离子自由基均显示出明显的清除或抑制作用,总抗氧化能力明显增加,且上述作用均呈一定的剂量依赖性.其中药物对DPPH清除作用的IC50值为0.338 mg/m L,对羟基自由基清除作用的IC50值为18.713mg/m L,对超氧阴离子抑制的最大活性值高达263.1U/L,总抗氧化能力也达到19.76 m M.表明藤茶具有确切的体外抗氧化活性.     

洋葱不同溶剂提取物体外抗氧化活性评价

通过测定还原力、螯合能力及其对羟基自由基、DPPH自由基、超氧阴离子自由基的清除能力等实验研究了洋葱5种不同溶剂提取物的体外抗氧化活性。实验结果表明：洋葱水提物的还原力最强,对DPPH自由基、超氧阴离子自由基和羟基自由基清除能力也最强;丙酮提取物对Fe2＋的螯合能力最强。综合评价,洋葱水提取物的抗氧化活性最强。     

海带抗氧化多酚的制备及活性研究

用1:1的氯仿:甲醇超声提取海带成分,并用石油醚、乙酸乙酯和正丁醇依次进行萃取,利用DPPH法、邻二氮菲-Fe2+氧化法、铁氰化钾还原法和邻苯三酚自氧化进行抗氧化实验,同时与抗氧化剂2,6-二叔丁基对甲酚(BHT)和没食子酸(GA)进行对照。结果显示海带提取物与各萃取组分均具有较强的抗氧化能力,其中乙酸乙酯提取物(EA)抗氧化活性最强。在50μg/mL浓度时,EA清除DPPH自由基、羟自由基、超氧阴离子自由基的能力和还原能力均高于抗氧化剂BHT,且清除超氧阴离子自由基的能力也高于GA;另外,Aqueous组分在所有测定浓度下清除羟自由基能力均高于GA,清除O2-的能力也高于BHT。海带各提取物总酚含量的分析表明总酚含量与抗氧化活性之间具有一定的相关性,总酚含量高其抗氧化能力也相应提高,表明多酚是提取物中重要的抗氧化成分。4种抗氧化方法的比较表明DPPH法的相关系数最高(R=0.987),是海带体外抗氧化实验最有效的方法。     

超级黑糯玉米芯色素的抗肿瘤和体外抗氧化作用

为研究超级黑糯玉米芯色素(super black glutinous corncob pigment,SBCP)对肿瘤细胞的增殖抑制效应和体外抗氧化活性.采用MTT法检测了SBCP对人肝癌细胞系BEL-7402以及胃癌细胞系SGC-7901增殖的影响;在体外化学模拟的条件下,通过建立DPPH自由基、羟基自由基、超氧阴离子自由基、还原力试验,采用比色法测定对比了SBCP和抗坏血酸(Vc)对DPPH自由基、羟基自由基和超氧阴离子的清除作用以及还原能力.结果表明SBCP对BEL-7402细胞和SGC--7901细胞增殖有明显的抑制作用,且随药物浓度的增大而增强;SBCP对两种肿瘤细胞的半数抑制浓度(IC50)分别为4.13 mg/mL和3.83 mg/mL.SBCP还具有较好的抗氧化作用,对羟基自由基和超氧阴离子的清除作用分别是Vc的1.4倍和1.23倍,还原能力是Vc的1.77倍,但对DPPH自由基的清除作用略低于Vc.SBCP在癌症预防和治疗以及食品保健方面具有潜在的应用价值;SBCP具有很好的体外抗氧化活性.     

暹罗鳄多肽粉的生物效应研究

在获得暹罗鳄(Crocodylus siamensis)多肽粉的基础上,进一步研究了暹罗鳄多肽粉对羟基自由基(.OH)、超氧阴离子自由基(O2-.)和1,1-二苯基-2-苦苯肼自由基(DPPH)的清除作用以及总还原力,以揭示其抗氧化能力.同时研究了暹罗鳄多肽粉对酪氨酸酶活性抑制作用.结果显示,暹罗鳄多肽粉具有较强的抗氧化、清除自由基作用,其总还原力与暹罗鳄多肽粉含量呈正相关,对.OH、O2-.和DPPH的半清除浓度HSC50分别为1.2,2.1和6.5mg/mL.暹罗鳄多肽粉对酪氨酸酶活力有明显的抑制作用,其IC50为6.60mg/mL.结果表明,暹罗鳄多肽粉具有一定的生物学功效,是一种天然的保健品.     

L-抗坏血酸-6-对羟基苯甲酸酯的合成及抗氧化活性研究

采用直接酯化法,合成了L-抗坏血酸-6-对羟基苯甲酸酯(APHB),并从清除羟自由基、超氧阴离子自由基、DPPH自由基能力及还原能力测试4个方面研究了它的体外抗氧化活性。结果表明,L-抗坏血酸-6-对羟基苯甲酸酯对上述3种自由基均有较好的清除效果,还原能力也较强,其抗氧化性能总体上与VC相当,优于市面上常用的抗氧化剂TBHQ,是一种有潜力的VC衍生物。     

复方圣愈汤挥发油成分比较及其体外抗氧化性研究

对少林伤科复方圣愈汤挥发油的化学成分进行分析并对其进行体外抗氧化活性初步研究。采用水蒸气蒸馏法提取圣愈汤挥发油,运用气质联用(GC-MS)方法分析,并运用紫外分光光度计分别测定该复方挥发油对1,1-二苯基-2三硝基苯肼(DPPH)自由基、超氧阴离子自由基及羟基自由基的清除能力。实验结果表明,圣愈汤挥发油提取不同时段圣愈汤挥发油成分与含量存在显著差异。圣愈汤挥发油化学成分对DPPH、超氧阴离子自由基及羟基自由基清除能力测定结果较之BHT也均优于后者,圣愈汤挥发油具有较好的体外抗氧化活性。     

枸杞多糖体清除自由基活性研究

采用超氧阴离子自由基体系、羟基自由基体系、烷基自由基引发的亚油酸氧化体系、二苯代苦味肼基自由基DPPH体系,对枸杞多糖的抗氧化活性进行了研究,并同Vc进行了比较.结果表明：枸杞多糖对这几种自由基均有不同程度的清除作用,其对超氧阴离子清除作用不明显;清除羟基自由基能力与Vc相当;在较小浓度时,清除烷基自由基和DPPH自由基能力弱于Vc,但在较高浓度与Vc接近.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the