黄酮类抗氧化剂的构-效关系

天然黄酮是广泛存在于自然界的酚类抗氧化剂之一,其抗氧化活性与清除自由基的能力密切相关.综述了几种研究抗氧化剂活性中常用的自由基检测方法与评价指标,并详细分析了结构因素影响黄酮类化合物抗氧化活性的机制与规律.认为黄酮类化合物的抗氧化活性主要取决于羟基的相对位置而非数目,具有色原酮结构的黄酮2-3位上不饱和双键也会在一定程度上增强其抗氧化活性,C环吸电子性质或羟基成甙则会使天然黄酮抗氧化能力降低,与金属离子的络合也是黄酮阻止自由基氧化的途径之一.对黄酮类抗氧化剂构-效关系的研究为筛选高效抗氧化剂和天然黄酮的结构修饰提供了理论依据.     

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。     

野紫苏中黄酮类化合物的研究

从野紫苏中分得6个黄酮类化合物,经理化性质和波谱数据分析,确定为5,7-二羟基-4’-甲氧基黄酮1;5-羟基-7,4’-二甲氧基双氢黄酮醇2;山奈酚-3-O-β-D-葡萄糖甙3;檞皮素-3-O-β-D-葡萄糖甙4;5-羟基-3’-甲氧基双氢黄酮-7-O-芸香糖甙5;5-羟基-4’-甲氧基黄酮-7-O-芸香糖甙6。除化合物1和2外,其余4个黄酮类化合物为首次从该属植物中得到。     

鹊肾树叶提取物抗氧化活性研究

采用分光光度法测定鹊肾树叶各提取物对DPPH自由基、羟基自由基、超氧阴离子自由基的清除能力及其还原能力。结果表明:鹊肾树叶各提取物均有很好的抗氧化活性,其中以乙酸乙酯提取物抗氧化活性最强,甚至优于人工合成抗氧化剂BHT。鹊肾树叶乙酸乙酯提取物是一种很好的天然抗氧化剂,有很好的开发价值。     

蝎子七化学成分的研究

从甘肃天祝县的蝎子七全草中分离鉴定出了15个化合物，其中2个为新化合物，报道9个已知化合物：阿魏酸、4-豆甾烯-3-酮、紫丁香甙、5，8，2′-三羟基-5′—甲氧基双氢黄酮、异鼠李素、槲皮素-3-O-鼠李素、山奈素-3-O-β-D-葡萄糖甙、洋芥素-7-O-β-D-葡萄糖甙、5-羟基-4-甲氧基黄酮-7-O-β-芸香甙。上述成分均首次从该植物中分离。     

黄芩黄酮对自由基的清除作用的ESR研究

采用电子自旋共振（ＥＳＲ）法和自旋捕获技术研究了中药黄芩中四种主要黄酮（黄芩素、黄芩甙、汉黄芩素和汉黄芩甙）的自由基清除作用及可能的作用机理．结果表明黄芩素和黄芩甙对羟自由基、超氧阴离子自由基、烷过氧自由基及ＤＰＰＨ自由基有较强的清除作用,而汉黄芩素和汉黄芩甙在测定浓度范围内对上述自由基作用较弱或无明显的清除作用．黄芩素和黄芩甙的自由基清除活性大大高于汉黄芩素和汉黄芩甙的原因是其结构中含有邻二酚结构     

罗汉果叶黄酮甙的分离与结构鉴定

以罗汉果叶为原料提取黄酮,用溶剂萃取、柱层析、HPLC纯化等方法进行黄酮甙的分离和提纯后,采用TLC、HPLC、IR、NM R、M S等分析方法进行结构鉴定。结果表明,罗汉果叶含有2种黄酮甙,它们分别是:山奈酚-3,7-O-α-L-二鼠李糖甙和槲皮素-3-O-β-D-葡萄糖7-O-α-L-鼠李糖甙。     

厚朴酚与和厚朴酚清除DPPH·的作用

 采用DPPH·法,以芦丁为对照品,在无水乙醇和乙醇-水介质中对厚朴酚与和厚朴酚进行了自由基清除活性的初步研究.结果表明,厚朴酚与和厚朴酚都具有自由基清除活性.此外,初步探讨了其自由基清除活性反应机理.     

中药半枝莲中黄酮类化合物的抗氧化活性

采用体积分数为70%的乙醇索氏提取法提取了中药半枝莲中的黄酮类化合物,并对其抗氧化活性进行了测定.结果表明,半枝莲中黄酮类化合物有较强的清除羟基自由基的能力,其还原能力与人工合成抗氧化剂BHT相当,表现出很强的抗氧化活性.     

黄芩黄酮对自由基的清除作用的ESR研究

采用电子自旋共振法和自旋捕获研究中药黄芩中四种主要黄酮的自由基清除作用及可能的作用机理。结果表明黄芩素和黄芩甙对羟自由基，超氧阴离子自由基，烷过氧自由基及ＤＰＰＨ自由基有较强的清除作用，页汉黄芩素和汉黄芩甙在测定深度深度范围内对上述自由基作用较弱或无明显的清除作用。     

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.     

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.     

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.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

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。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.