226 resultados para 263


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MCM-41 mesoporous molecular sieve and iron(II)-Phen/MCM-41 have been prepared and characterized by XRD, IR, NH3-TPD, BET and UV-Vis. The iron(II)-Phen/MCM-41 molecular sieve + 30% H2O2 system is capable of performing hydroxylation of phenol.

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研究了壬酸胆甾酯与甲基丙烯酸甲酯-甲基丙烯酸丁酯无规共聚物共混体系的等温结晶动力学.讨论了共聚物组成及分子链刚性对体系中胆甾液晶组分结晶速度及成核方式的影响

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Thermal properties of polyaniline (PAn), polytoluidine(POT) and polyanisidine(PAs) were examined by TG and DSC techniques. The weight-uptake of POT at 200-300 degrees C was observed and carefully discussed.

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采用热解柠檬酸盐法合成了粒径不同的LaCrO3纳米粉末,XRD分析表明,合成的LaCrO3为单相,正交晶系平均粒径随焙烧温度升高而明显增加;随焙烧时间增长略有增加,发现LaCrO3的电阻率随粒径的增加而增大:导电活化能随粒径的减小而变小

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本文研究了铽(Tb~(3-))对钐(Sm~(3-))-2-噻吩甲酰三氟丙酮(TTA)-氯代甲基三烷基铵(N_(263))-Triton X-100荧光体系的共发光效应,结果表明:Tb~(3-)的浓度1×10~(-5)~5×10~(-5)mol/L范围内体系的荧光强度最大.Sm~(3-)的浓度在1.0×10~(-9)~1.0×10~(-7)mol/L范围内与荧光强度呈线性关系,检测限为1.0X10~(-11)mol/L,方法灵敏,简便,用于混合稀土样品中痕量Sm~(3-)的测定,结果满意。

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A statistical thermodynamics theory of polydisperse polymer mixtures with strong interaction between dissimilar components based on a lattice fluid model is formulated. Expressions for the free energy, equation of state, phase stability and spinodal for a polydisperse, binary polymer mixture with strong interaction are derived.

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The laser-atomic-beam spectroscopy technique has been used to make measurements of the hyperfine structure in some odd parity levels of thulium by stepwise excitation. With the experimental results the magnetic dipole hyperfine constants A for the four levels in the configurations 4f12 5d6s6p and 4f12 (H-3(5))6s2 6p3/2 and for two intermediate levels have been obtained.

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本工作研究了多分散和单分散聚氧化乙烯-聚苯乙烯-聚氧化乙烯三嵌段共聚物(PEO-PS-PEO)的结晶行为,及这些试样按非晶型嵌段共聚物进行微相分离后再结晶的结晶特点.

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本文研究了铽(Tb)、钇(Y)、钆(Gd)及它们的混合物对铕(Eu)-噻吩甲酰三氟丙酮(TTA)-氯化甲基三烷基铵(N_(263))-Triton X-100体系的共发光效应,发现稀土离子混合物的共发光效应具有线性加和性,用混合共发光体系不仅能保持单个稀土离子的共发光体系的增敏性,而且抗干扰能力增强,并经过实际样品分析的验证,结果令人满意。

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合成了四个甲基乙撑桥联二环戊二烯基环戊二烯基稀土四氢呋喃配合物,采用元素分析、红外光谱、核磁共板、热失重和质谱等方法对所得到配合物进行表征,并用X光衍射法测得Me_4C_2(C_5H_4)_2SmC_5H_3(THF)的晶体结构。该晶体属正交晶系C_(e2a)空间群,a=1.1696(6),b=1.2539(5),c=2.9432(15)nm;V=4.316(4)nm~3,z=8,D_c=1.54g·cm~(-3)。三个环戊二烯基Sm-C(η~5)距离分别为0.272(3),0.276(3),0.278(3)nm和Sm-O键长为0.253(1)nm。

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本文应用取代基效应(SCS)方法研究了乙烯-乙烯醇(EVA)共聚物,得到了羟基(-OH)在两种不同溶剂中的SCS参数:在苯酚+重水(80/20W/W)中参数为S_1=42.77±0.08ppm,S_2=7.155±0.06ppm,S_3(s)=-4.08±0.02ppm,S_3(t)=-3.09±0.02ppm,S_4=0.48±0.03ppm,S_5=0.26±0.05ppm,在以邻二氯苯为溶剂时参数为S_1=44.97±0.61ppm,S_2=7.40±0.00ppm,S_3(s)=-4.51±0.17ppm,S_3(t)=-3.13±0.00ppm,S_4=0.63±0.04ppm,S_5=0.36±0.00ppm,同时利用所得到的SCS参数对该共聚物的~(13)C NMR谱进行了归属。

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本文首次提出了Eu~(3+)-TTA-N_(263)-异辛基苯氧基聚乙氧基乙醇(Triton X-100)体系的荧光分光光度法测定铕。在此最佳条件下铕的测定下限可达0.9ng/ml,并可允许存在一定量的其它共存稀土离子。该法用于测定包头混合稀土氧化物中的痕量铕,获得较满意的结果。

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本文叙述了采用色度法对稀土LF_(21)铝合金氧化膜电解着色进行的研究。结果表明:电解着色液浓度、着色电压、电流密度、温度、时间以及合金成分等因素对电解着色均有较大影响。稀土可显著提高着色速度,稀土含量为0.30%时电解着色膜性能最佳。

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以Nd(naph)_3-Al(i-Bu)_3-Al_2Et_3Cl_3为催化剂,在-10~5℃下对异戊二烯(Ip)本体聚合的动力学进行了初步研究。发现单体转化率小于5%时,体系呈非稳态聚合;单体转化率大于50%时聚合受扩散控制;体系处于两者间则为稳态聚合。本体聚合的稳态聚合反应速率方程式为:R_p=K_p[Ln]~(196)M_0,计算出Ip本体聚合的表现活化能为69.9kJ/mol。