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化橘红水溶性多糖的化学及体外抗氧化活性的研究 总被引:8,自引:0,他引:8
化橘红粗粉经热水提取、乙醇沉淀、Sevage法脱除蛋白、CTAB(溴化十六烷基三甲胺 )配合法进一步分离纯化得化橘红多糖 ( ECP)。经 Saphadex- 2 0 0凝胶柱层析 ,硫酸 -酚法证实 ECP为均一多糖组分。气相色谱分析表明 ECP含有 D-木糖、D-葡萄糖、D-半乳糖、L-阿拉伯糖、D-甘露糖和一个未知物 (待定 ) ,它们的摩尔比为 1∶ 3.1∶ 3.6∶ 2 .8∶ 1 .8∶ 3.9。红外光谱分析表明 ECP具有典型的多糖吸收峰 ,并具有 α-构型糖苷键。紫外光谱显示在 2 60 ,2 80 nm处未见有核酸和蛋白质特征吸收峰。该多糖体外可清除邻苯三酚自氧化体系产生的超氧阴离子自由基 ( SAFR) ,且呈剂量依赖关系。结果表明 ECP为一杂多糖 ,体外有直接清除 SAFR的抗氧化活性 相似文献
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银杏外种皮经乙醚脱脂后,用热水抽提,D900大孔弱碱阴离子交换树脂脱色提纯,浓缩后,乙醇沉淀得银杏外种皮粗多糖。银杏外种皮多糖具有抗癌、提高免疫力、降血脂、止咳祛痰等功能,所以利用银杏外种皮多糖可以配制抗癌的药品和保健食品,具有开发和应用前景。 相似文献
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银杏外种皮经乙醚脱脂后,用热水抽提,D900大孔弱碱阴离子交换树脂脱色提纯,浓缩后,乙醇沉淀得银杏外种皮粗多糖。银杏外种皮多糖具有抗癌、提高免疫力、降血脂、止咳祛痰等功能,所以利用银杏外种皮多糖可以配制抗癌的药品和保健食品,具有开发和应用前景。 相似文献
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黄芪经沸水浴提取、用Sevag法去蛋白纯化、经50%乙醇多糖分级、离心,得沉淀即H_1,浓缩上清液,沉淀即H_2;对H_1进行化学修饰得甲基化多糖;用DPPH·法对三种多糖进行抗氧化性测试,三种多糖抗自由基能力:H_2甲基化多糖H_1。它们对自由基的清除作用与其浓度呈正相关性。用水煮醇沉法提取多糖,并进行分级和化学修饰,来研究它们对自由基的清除作用,为更好地研究黄芪药用机理,扩大黄芪资源综合利用提供依据。 相似文献
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茶多糖的纯化工艺研究 总被引:1,自引:0,他引:1
实验研究了茶多糖的提取纯化工艺,主要考察醇沉、除蛋白、脱色工艺条件,得适宜的纯化工艺:提取液浓缩至1/4倍体积后,加入4倍体积95%乙醇沉淀6h,离心得茶多糖粗品。多糖粗品溶于水,并用Sevag法去除蛋白质,多糖溶液与Sevag试剂比为4:1,析出的蛋白质离心除去。清液最后经非极性大孔吸附树脂ADS-8脱色,冷冻干燥得到茶多糖制品,多糖含量65%,产率2.05%。 相似文献
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2-乙氧基-4-氨基苯酚合成的新方法 总被引:1,自引:0,他引:1
以邻苯二酚和乙醇为原料,通过取代、硝化反应先制得2-乙氧基-4-硝基苯酚;然后在钯碳催化剂作用下进行加氢反应制得2-乙氧基-4-氨基苯酚粗品;粗产物用苯-石油醚进行重结晶得到纯品。产品总收率为60·5%。 相似文献
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In this study self‐supporting, resilient, load bearing polybutadiene ‐ soybean oil gels were obtained. The gels were made by dissolving polybutadiene (PBD) in soybean oil (SO) and selectively crosslinking PBD with a free radical source. PBD concentration, free radical source concentration, and the temperature and time of the crosslinking reaction were varied, and the effects of these changes on the mechanical properties of the gels were examined. Our experiments show that successful gelation is possible within PBD concentration limits of 7.5 to 12%, peroxide concentration between 25 to 100% (based on PBD), temperature between 110°C and 130°C and reaction times of 3 hours with tert.butyl‐peroxybenzoate as the free radical source. The crosslinking reaction was followed by IR and H‐NMR spectra, and the crosslinking density was followed by compression testing and swelling behavior. Higher radical source concentration and higher PBD concentration gave gels with better mechanical properties. The spectra and the viscosity increase of SO extracted from the gels indicate that there is dimer and trimer formation of SO during the reaction. The spectra of the PBD extracted from gels indicate that SO was added to PBD in a small but measurable amount. Integration of peak intensities in the NMR spectrum of methylene groups of PBD and methylene groups of triglyceride indicated one triglyceride molecule for approximately 45 repeating units in PBD. The modulus of the best gel sample (PBD 10%. peroxide 50%) was 1.96 × 10?2 MPa. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2240–2246, 2005 相似文献
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不同预处理方法对稻秸纤维表面性质的影响 总被引:1,自引:0,他引:1
通过对稻秸原料进行水热、酸碱和冷等离子体预处理,分析了纤维表面的浸润性及表面自由基浓度的变化。研究表明,经水热及酸碱预处理后,纤维与水的接触角为90o,稻秸纤维的浸润性改善不明显,经冷等离子改性后,稻秸纤维表面浸润性改善非常明显。水热及乙酸处理有利于提高稻秸纤维的表面自由基浓度,碱处理则降低了稻秸纤维的表面自由基浓度。 相似文献
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A new dinitroxide (1,4‐di (1‐oxy‐2,2,6,6‐tetramethyl‐1‐piperidin‐4‐yl)‐xylene) (DTPX) was synthesized and successfully used in stable free radical polymerization of styrene. The results of the polymerizations showed that the DTPX was a suitable mediating agent for stable free radical polymerization of styrene. However, it was found that the dinitroxide mediating process resulted in a higher level of decomposition of the internal bisalkoxyamine linkage in the polymer chain, which resulted in polymers possessing a terminal alkoxyamine and an adjacent hydroxylamine, and the decomposition became more obvious at high conversion through monitoring the change of molecular weights with the conversion by gel permeation chromatography and the polymer structure by 1H‐NMR. The reaction temperature showed obvious effects on the polymerization, and the polymerization of styrene at 110°C led to a better controlled polymerization than that at 125°C with narrower molecular weight distributions and slight decomposition of the nitroxide up to monomer conversions of 76.7%, however, the rate of the polymerization was decreased and an induction period appeared at 110°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1137–1145,2006 相似文献
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Forgotten monomers: isotactic polymers from N‐benzyl‐3‐methylenepyrrolidin‐2‐one via free radical polymerization 下载免费PDF全文
N‐Benzyl‐3‐methylenepyrrolidin‐2‐one ( 3 ) was synthesized and homopolymerized under free radical conditions. The configurational microstructure of poly(N‐benzyl‐3‐methylenepyrrolidin‐2‐one) ( 4 ) is isotactic with a minor tendency to syndiotacticity. Monomer 3 was also homopolymerized in water in the presence of methylated β‐cyclodextrin. The glass transition temperature of 4 of 124 °C was compared with the lower value of 61 °C of the ring‐opened analogue poly(N‐benzyl‐N‐ethylacrylamide). © 2015 Society of Chemical Industry 相似文献
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In this paper, the high value-added (ultra-low degree of polymerization [ULDP]) polyvinyl alcohol (PVA) product was successfully prepared by oxidative chain scission method with sodium hypochlorite as an oxidant. When the molar ratio of PVA to NaClO is not less than 1:1.8, the reaction is stirred for several hours (≥2 h) at a temperature not exceeding 50°C. After precipitation and washing in methanol, PVA with polymerization degree of 38–150 can be obtained after drying. The infrared spectrum (IR) and nuclear magnetic hydrogen spectrum (1H-NMR) test proved that the product obtained by this method is indeed PVA. The results of 1H-NMR also showed that the chain broken has no selectivity and the stereoregularity of hydroxyl group did not change significantly. Through radical quenching experiment and electron paramagnetic resonance (EPR) analysis, it is proved that OCl− is the main active oxide, ·Cl makes the oxidative chain scission process can be realized quickly, and ·OH is an indispensable factor for obtaining ULDP PVA. Under the combined action of these three, high value-added PVA with ULDP was successfully prepared. Additionally, the sodium hypochlorite oxidized the ·OH captured by 5,5-dimethyl-1-pyrroline-n-oxide (DMPO-OH) to 2-hydroxy-5,s-dimethyl-1-pyrroline-N-oxide (HDMPO-OH) in an alkaline environment. 相似文献
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An experimental investigation of the kinetics of the bulk free radical copolymerization of styrene/butyl acrylate initiated with 2,2′-azobisisobutyronitrile (AIBN) was conducted at 50°C using various initiator concentrations and initial monomer ratios including the azeotropic composition. Reactivity ratios were determined by analyzing composition data using the error-in-variables model. The experiments, designed using the Tidwell-Mortimer criterion, were conducted in sealed ampoules at 50°C to low conversion levels (< 7%). From the calculated reactivity ratios, the azeotropic composition was determined and further experiments were run at these conditions as well as at two other initial monomer feed compositions in order to collect composition, rate and molecular weight data. The experiments were run through the full conversion range at two different initiator concentrations. 相似文献
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Polyether polyurethane networks were prepared in solution at 25 and 60°C, using various organotin catalysts. The presence of a free‐radical initiator [viz. azobisisobutyronitrile (AIBN)] in the reaction media has no effect on the catalytic efficiency of organotin(IV) compounds, whereas it causes severe deactivation of organotin(II) compounds. This effect was explained by the following mechanism: formation of a cyclic 1 : 1 complex by coordination of the nitrile groups of AIBN with the tin(II) atom, which both reduces the effective catalyst concentration and allows the early decomposition into radicals, as previously seen, leading to tin oxidation. The addition of a free‐radical scavenger such as 3‐tert‐butyl pyrocatechol allows the maintenance of the catalyst efficiency of organotin(II) compounds at their reference level. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1929–1937, 2002 相似文献