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测定果胶中甲酯化取代度的方法 被引量:9
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作者 郑芸 方积年 《天然产物研究与开发》 CAS CSCD 2006年第4期709-712,共4页
本文综述了果胶类化合物的甲酯化取代度的测定方法,包括比色、滴定、高效液相、气相、核磁共振、红外IR等方法。其中有些方法可以同时测定果胶的甲酯的取代方式或乙酰化取代度。
关键词 果胶 酯化取代 乙酰化取代
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水稻根系果胶去甲酯化促进细胞壁磷再利用的机制探究 被引量:2
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作者 赵旭升 朱晓芳 +1 位作者 吴启 沈仁芳 《土壤学报》 CAS CSCD 北大核心 2018年第5期1190-1198,共9页
在缺磷条件下,水稻根系细胞壁中的果胶组分能促进细胞壁磷的再利用,而其中的潜在机制仍有待进一步的研究。选取粳稻品种Nipponbare(Nip)和籼稻品种Kasalath(Kas)作为试验材料,研究了在缺磷条件下,水稻内源磷可利用水平的变化及其差异,... 在缺磷条件下,水稻根系细胞壁中的果胶组分能促进细胞壁磷的再利用,而其中的潜在机制仍有待进一步的研究。选取粳稻品种Nipponbare(Nip)和籼稻品种Kasalath(Kas)作为试验材料,研究了在缺磷条件下,水稻内源磷可利用水平的变化及其差异,并探究了产生这种差异的原因。结果表明:在缺磷处理后,水稻体内的可溶性磷含量迅速降低,而Nip根系和地上部的可溶性磷含量均一直高于Kas。同时Nip根系中释放出了更多的细胞壁磷,说明相对于Kas而言,Nip的内源磷再利用能力更强。缺磷胁迫时,与Kas相比,Nip可通过提高根系中的果胶甲酯酶活性,维持较低的果胶甲酯化度。体外试验又表明,甲酯化度越低的果胶,活化难溶态磷的能力越强。综上,缺磷胁迫下,水稻可通过提高根系果胶甲酯酶活性,将细胞壁的果胶甲酯化度维持在较低水平,从而促进细胞壁磷的释放来增加体内的可溶性磷含量,以供其他部位再利用。 展开更多
关键词 水稻 缺磷 磷再利用 细胞壁 果胶酯酶 果胶甲酯化度
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提取方法对马铃薯渣果胶多糖组成及分子链构象的影响 被引量:6
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作者 孙玮璇 田金虎 +3 位作者 陈健乐 陈士国 刘东红 叶兴乾 《中国食品学报》 EI CAS CSCD 北大核心 2021年第7期216-224,共9页
采用酸(柠檬酸)、碱(氢氧化钠)、酶(多聚半乳糖醛酸水解酶)3种方法从马铃薯渣中提取果胶多糖,研究不同提取方法对多糖得率、单糖组成、酯化度、分子质量及分子链构象的影响。结果表明:3种提取方法得到的马铃薯渣果胶多糖均以富含半乳糖... 采用酸(柠檬酸)、碱(氢氧化钠)、酶(多聚半乳糖醛酸水解酶)3种方法从马铃薯渣中提取果胶多糖,研究不同提取方法对多糖得率、单糖组成、酯化度、分子质量及分子链构象的影响。结果表明:3种提取方法得到的马铃薯渣果胶多糖均以富含半乳糖侧链的鼠李半乳糖醛酸聚糖I(RG-I)结构为主。其中,碱提果胶多糖得率最高(23.1%),其次为酸提(11.7%)和酶提(6.0%)。3种果胶多糖甲酯化度均较低(0~7.5%),而乙酰化度较高,且酸提和酶提马铃薯渣果胶多糖的乙酰化度高于碱提(分别为13.6%,10.7%,6.6%)。分子质量分析结果表明,酶提果胶多糖的分子质量最高(1706.3 ku),且分布最窄。通过Mark-Houwink-Sakurada方程判断:酶提果胶多糖的分子链形态较为聚集,接近球状构象;酸提果胶多糖介于球状和线团状构象之间;碱提果胶多糖分子链形态最为疏松,呈无规线团状构象。 展开更多
关键词 马铃薯渣 果胶多糖提取 甲酯化度 乙酰化 链构象
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Simulation for Transesterification of Methyl Acetate and n-Butanol in a Reactive and Extractive Distillation Column Using Ionic Liquids as Entrainer and Catalyst 被引量:12
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作者 蔡贾林 崔现宝 杨志才 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2011年第5期754-762,共9页
A new reactive and extractive distillation process with ionic liquids as entrainer and catalyst (RED-IL)was proposed to produce methanol and n-butyl acetate by transesterification reaction of methyl acetate with n-b... A new reactive and extractive distillation process with ionic liquids as entrainer and catalyst (RED-IL)was proposed to produce methanol and n-butyl acetate by transesterification reaction of methyl acetate with n-butanol. The RED-IL process was simulated via a rigorous model, and high purity products of methanol and n-butyl acetate can be obtained in such a process. The effects of reflux ratio, feed mode, holdup, feed location, entrainer ratio and catalyst concentration on RED-IL process were investigated. The conversion of methyl acetate and purities of products increase with the holdup in column, entrainer ratio and catalyst content. An optimal reflux ratio exists in RED-IL process. Comparing to the mixed-feed mode, the segregated-feed mode is more effective, in which the optimal feed locations of reactants exist. 展开更多
关键词 ionic liquid reactive and extractive distillation transesterification reaction azeotropic mixture
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Kinetics of the Mono-esterification Between Terephthalic Acid and 1,4-Butanediol 被引量:4
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作者 田文玉 曾作祥 +2 位作者 薛为岚 李应宾 章添钰 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2010年第3期391-396,共6页
The chemical kinetics of the monoesterification between terephthalic acid(TPA)and 1,4-butanediol (BDO)catalyzed by a metallo-organic compound was studied using the initial rate method.The experiments were carried out ... The chemical kinetics of the monoesterification between terephthalic acid(TPA)and 1,4-butanediol (BDO)catalyzed by a metallo-organic compound was studied using the initial rate method.The experiments were carried out in the temperature range of 463-483 K,and butylhydroxyoxo-stannane(BuSnOOH)and tetrabutyl titanate[Ti(OBu)4]were used as catalyst respectively.The initial rates of the reaction catalyzed by BuSnOOH or Ti(OBu)4 were measured at a series of initial concentrations of BDO(or TPA)with the concentration of TPA(or BDO)kept constant.The reaction orders of reagents were determined by the initial rate method.The results indicate that the reaction order for TPA is related with the species of catalyst and it is 2 and 0.7 for BuSnOOH and Ti(OBu)4 respectively.However,the order for BDO is the same 0.9 for the two catalysts.Furthermore,the effects of temperature and catalyst concentration are investigated,and the activation energies and the reaction rate constants for the two catalysts were determined. 展开更多
关键词 ESTERIFICATION 1 4-butanediol terephthalic acid KINETICS
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Improvement of the physical properties of poly(methyl methacrylate) by copolymerization with N-pentafluorophenyl maleimide; zero-orientational and photoelastic birefringence polymers with high glass transition temperatures
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作者 TAGAYA Akihiro LOU LiPing +2 位作者 IDE Yoko KOIKE Yasuhiro OKAMOTO Yoshiyuki 《Science China Chemistry》 SCIE EI CAS 2012年第5期850-853,共4页
Copolymers of N-pentafluorophenyl maleimide (PFPMI) with methyl methacrylate (MMA) were synthesized by a free radical initiator, such as AIBN. The refractive indexes of the copolymers remained nearly constant (1.4970 ... Copolymers of N-pentafluorophenyl maleimide (PFPMI) with methyl methacrylate (MMA) were synthesized by a free radical initiator, such as AIBN. The refractive indexes of the copolymers remained nearly constant (1.4970 at 532 nm) regardless of the polymer composition. These copolymers also showed high thermal stability. The orientational and photoelastic birefringence of the copolymers obtained were measured. Since both of the orientational and photoelastic birefringences of PMMA are negative whereas poly(PFPMI) exhibits positive, thus we have obtained nearly zero orientational and photoelastic birefringence polymers when the ratios of MMA/PFPMI were 91.8/8.2 and 97.0/3.0 mol%, respectively. Based on the experimental data, the ratios of MMA/PFPMI for zero birefringence were determined to be 88.9/11.1 and 93.8/6.2 mol% for orientational and photoelastic birefringence, respectively. The Tgs of corresponding copolymers were estimated to be 128 and 122 ℃. 展开更多
关键词 N-pentafluorophenyl maleimide copolymers orientational birefringence photoelastic birefringence
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