209 resultados para 7140-234
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研究虎眼万年青多糖对机体非特异性免疫和体液免疫功能的影响.方法:采用小鼠碳廓清单核巨噬细胞吞噬功能测定法筛选出虎眼万年青多糖中的有效组分,即60%醇浓度的虎眼万年青中性多糖(OCAPS3);采用溶血素测定方法研究不同剂量OCAPS3对小鼠抗体形成的影响.结果:OCAPS3能显著提高巨噬细胞的吞噬功能以及抗体生成的能力.结论:证明虎眼万年青多糖能有效地增强小鼠的非特异性免疫和体液免疫功能.
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A novel AB-monomer, 3-maleimidostilbene (ST-MAI), was synthesized. DSC investigation indicated that the ST-MAI monomer melted at 127 degrees C and thermally polymerized in the temperature range of 180 similar to 300 degrees C. LR investigation on the thermal polymerization processes proved that the thermal polymerization included not only copolymerizaiton between stilbene and maleimide, but also homopolymerization of maleimide. The largest reaction conversion of maleimide and stilbene unit in a ST-MAI monomer was about 82% and 50% respectively. The glass transition temperature of cured ST-MAI resin was 234 degrees C, determined by DSC. The decomposition temperatures for 10% weight loss was above 430 degrees C in both air and nitrogen atmospheres.
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利用多核Nd-Al双金属配合物可单独引发双烯烃聚合的特点,考察了烷基铝种类对丁二烯加聚过程的影响,并与一般混合稀土催化体系进行了比较.烷基铝对活性体催化活性的影响与其用量有关,低n(Al)/n(Nd)值时,活性次序为:AlMe3,AlEt3,HAlBui2>Al(C8H17)3>AlBui3;高n(Al)/n(Nd)值时,活性次序相反:AlMe3,AlEt3,HAlBui2<Al(C8H17)3<AlBui3.烷基铝链转移作用强弱次序为:HAlBui2≥AlEt3>AlBui3>AlMe3>Al(C8H17)3.根据聚丁二烯微观结构与其分子量的关系,可将烷基铝对聚丁二烯顺式含量的影响分为3类:(1)AlEt3和Al(C8H17)3;(2)HAl-Bui2和AlBui3;(3)AlMe3.所得结果有助于对稀土催化定向聚合过程的深入了解.
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A series of samples having the composition of La2-xSrxNiO4(0 less than or equal to x less than or equal to 1) were prepared and used as catalysts for NH3 oxidation. It was found that the La and oxygen vacancies exist in the La2-xSrxNiO4-lambda(0 less than or equal to x less than or equal to 1). The unit cell volume decreases with the increase of x. For bath c and a parameters there appeared a turning point at x = 0.5. Doping with a lower valence cation Sr2+ in the case of La2NiO4 resulted in an increase of Ni3+, consequently the formation of oxygen vacancies, the increase of reducing ability and the increase of catalytic activity. In the oxygen TPD of La2-xSrxNiO4(0 less than or equal to x less than or equal to 1) appeared three peaks, the alpha' peak at about 400K was attributed to the surplus oxygen desorption, the a peak at 700K which approaches to a maxium at x = 0.6 was attributed to the oxygen adsorbed at oxygen vacancies. The beta peak at about 1000K which depends closely on the x and favors the catalytic activity was attributed to the reduction of Ni3+. The catalytic activity of La-2-x SrxNiO4 mixed oxides in the NH3 oxidation in general could be attributed to the extent of the redox reaction: 2Ni(2+) + O-2 + V-0(..) reversible arrow 2Ni(3+) + 20(-) where V-0(..) representes the oxygen vacancies and O- the oxygen species adsorbed at the vacancies.
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The dissolution behaviours of La and Nd in their chloride molten salts were studied by means of the see-through cell, electrochemical weak polarization and quantum chemistry (extended Huckel molecular orbital). The reasons for the low current efficiencies of rare earth metals and the difference between La and Nd in their own chloride electrolytes on the basis of the solubility, rate of dissolution, and existing state of the metals dissolved as well as the structure of the melts, are discussed.
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本文报道了La_(2-x)Sr_xNiO_(4-λ)(O≤x≤1)系列复合氧化物的固体结构性质和用于氨的氧化制硝酸的催化性能.La_(2-x)Sr_xNiO_(4-λ)的晶胞体积Ⅴ随x的增大而逐渐减小;c轴在x≤0.5前逐渐增大,在x≥0.5后逐渐减小.a轴在x≤0.5前逐渐减小,在x≥0.5后基本保持恒定.在x≤0.5前,La_(2-x)Sr_xNiO_(4-λ)中存在氧过剩,在x≥0.5后存在氧缺陷.TPD表明,a氧(吸附在氧缺陷上的氧)在x=0.6时出现极大,β氧(晶格氧)随x增大而逐渐增大.La_(2-x)Sr_xNiO_(4-λ)的氧化还原能力,Ni~(3+)的量,氨氧化的NO选择性都随x增大而增加.由此得出,Ni~(3+)是催化剂的活性离子,β氧是氨的氧化的活性氧种,在La_(2-x)Sr_xNiO_(4-λ)上的氨的氧化遵循氧化还原(Redox)机理.
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聚(苯乙烯-丙烯酰胺)载体-NdCl_3络合物二元催化剂李玉良,郑文治,于广谦,李晓莉(中国科学院长春应用化学研究所,130022)二元催化剂较三元催化剂,具有节省资源、简化工艺流程和有益于提高经济效益的优点。虽然聚[苯乙烯-甲基丙烯酸β(甲基亚硫酰?..
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本文研究了 TiO_2-Li_2O-Nb_2O_5:Eu~(3+)体系中固溶体形成的温度与组成的关系。化学通式为 Ti_(1-4x-y)EuLixNb_3xO_2,当 y=0.2,0
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熔盐结构具有远程无序、近程有序的特点,对其结构的表征要比完全有序的晶体和完全无序的气体困难得多.分布函数理论是迄今为止描述熔盐结构较为成熟的方法,它依据统计理论,从粒子间相互作用势能出发,去求解表征体系结构的径向分布函数.实验上获得径向分布函数主要是通过衍射法.在国内,熔盐径向分布函数的实验工作才刚刚开始.本文报导了采用X-射线衍射方法测定LaF_3-KF熔盐径向分布函数的结果.
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L-B膜即 Langmuir-Blodgett单分子膜,它是人为地利用分子间相互作用而建立起来的特殊分子体系。在L-B膜中分子是有序的准晶体排列,其性质有别于固体和晶体,因而有人将其称为物质的第五相。用米制备L-B膜的技术称为L-B技术。
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共混高聚物是具有优良性能的高分子材料,近些年来这类材料的应用越来越广泛,从而对共混高聚物的研究也逐渐深入。本文将应用化学蚀刻法对丙纶高分子材料结构做以探讨。丙纶是聚丙烯(PP)与聚对苯二甲酚乙二酯(PET)经物理共混而成的,由于PET的加入可以提高丙纶染色效果,因此扩大丙纶应用范围。我们对PP与PET共混物在不同温度不用铬酸液蚀刻不同时间,通过扫描电镜观察其形态结构。实验结果表明,铬酸蚀刻液对高分子材料晶区与无定型部分可以有选择的腐蚀,使晶区与无定型区形态清晰显露,从而达到提高共混物衬差效果,对研究共混高聚物结构具有重要意义。
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H(DEHP)是HEH(EHP)和HDEHP的同系物,它们的结构分别为:HDEHP,(GO)_2PO(OH);HEH(EHP),(GO)(G)PO(OH);H(DEHP),(G)_2PO(OH)。其中G为2-乙基已基。 希土元素萃取分离工艺化学表明,溶剂萃取希土元素对酸度的依赖关系及相邻希土元素间的分离因素值是选择萃取剂时应优先考虑的因素。HDEHP萃取剂对中、重希士元素反萃酸度高,HEH(EHP)是一个优良萃取剂,但对Er,Tm,Yb,Lu的反萃仍需5mol/l的酸。由于H(DEHP)分子中不含酯氧原子,使得它的pK_a值比HDEHP和HEH(EHP)的高。从而,用H(DEHP)萃取希土元素时需要的水相酸度更低,反萃更容易。而且H(DEHP)
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在钟罩式内极反应器中进行了六甲基二硅氧烷(HMDSO)和四氟化碳(TFM)混合气体等离子体聚合。用IR、XPS、X射线对聚合膜结构进行了表征。等离子体共聚合膜中含有Si和F,聚合膜中元素组成依赖于起始混合气体单体的比,Si/C元素比随着混合气体中TFM浓度增加而减小,而F/C比增大。测定了复合膜的气体透过性,等离子体共聚合方法是制备气体分离膜的可行方法。同时,还测定了等离子体聚合膜的接触角,并计算了表面能。