271 resultados para 225
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采用光化学法合成一种有机-无机电荷转移盐,(HMDH2)[H2PMo12O40]·AA·3H2O·DMF(HMD = 1,6-己二胺,AA = 乙醛,DMF = N,N-二甲基甲酰胺)超分子化合物。用元素分析,IR,固体漫反射电子光谱,ESR进行了表征。X-射线四圆衍射测定其晶体结构属三斜晶系,空间群 Pī,Mr=2081.68,晶胞参数a = 14.092(3),b =14.347(3),c =14.358(3)?,α=75.10(3),β=80.70(3),γ=80.73(3)°,V=2746.6(10)?3,Z=2,Dc=2.517g/cm3,F(000)=1970,μ(MoKα)=2.766mm- 1,全矩阵最小二乘法修正至R=0.0832,wR=0.2638。标题化合物是由1个质子化的1,6-己二胺、12-钼磷混合价杂多阴离子 [PMo12O40]4ˉ、3个水分子、2个乙醛分子和1个二甲基甲酰胺分子构成。
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A novel heteropoly tungstophosphates, H-8[P4W14O58Na4(H2O)(20)] . 16H(2)O, was synthesized by hydrothermal method and characterized by elemental analysis, IR spectrum and single-crystal X-ray structure analysis. The thermal stability of the compound was investigated by using TG-DTA. The crystal is triclinic system with space group P (1) over bar, a = 1. 137 9(2) nm, b=1. 363 2(3) nm, c=1. 627 1(3) nm; alpha=78. 20(3)degrees, beta=71, 20(3)degrees, gamma= 71. 62(3)degrees; V = 2. 252 5(8) nm(3), Z=1, M-r= 4 374. 38, D-c = 3. 225 mg/cm(3), mu = 18. 007 mm(-1), F(000)=1 972, R=0. 074 2, R-w=0. 200 4. The result of structure analysis shows that the anion of the compound consists of two PW7O29Na2(H2O)(10) subunits and two linked phosphorous atoms. A kind of microporous with size of 0. 661 4 nm X 0. 318 9 nm was formed in the crystal structure.
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用JJ-20型仪器化冲击仪研究了HIPS/SBS共混物在组成为100/0、100/5、100/10、100/15、100/20和100/25质量比下样品的Izod缺口冲击性能。结果表明,在组成范围内,随着SBS含量的增加,样品的Izod缺口冲击强度随之增加。质量比为100/25样品的Izod缺口冲击强度值(225.9J/m)比质量比为100/0的样品(108.7J/m)增加了1倍以上。通过对冲击断裂过程的分析表明,冲击强度的提高主要是由于缺口根部应力集中产生塑性区所消耗的裂纹引发能的提高引起的,而裂纹扩展能基本没有多大变化
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本文介绍了PDP用荧光粉的基本情况及其应用特性。归纳出基团敏化带位置的一般规律及阳离子对基团敏化带波长位移的影响。并指出,提高发光效率,改善荧光粉的热稳定性和辐照稳定性,开发新型稀土荧光粉等具有重要意义。
Resumo:
Single crystals of KLnN(Ln=La, Ce, Pr, Nd, Sm) can be grown in water solution with pH approximate to 1 similar to 2 at about 40 degrees C. Crystals of KLnN (Ln=La, Ce, Pr, Nd) are orthorhombic with space group Fdd2. KPrN crystal was grwon and its crystal structure was determined for the first time. The KPrN crystal parameters obtained by the direct method are as follows: a=21.411(3) Angstrom, b=11.2210(10)Angstrom, c=12.208(2) Angstrom, Z=6, R=0.0240. The TG-DTA curves of KLnN(Ln=La,Ce, Pr, Nd, Sm) demonstrate that the processes of dehydration, melt, irreversible phase transition and decomposition of NO3- take place in sequence with the temperature increasing(except KCN). There are three steps in the decomposition of NO3- in KLnN(Ln=La, Nd, Sm) while two steps in KLnN (Ln=Ce, Pr). K(2)Ln(NO3)(5). 2H(2)O are formed at about 225 degrees C by the reaction of the starting materials of KNO3 and Ln(NO3)(3). nH(2)O.
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采用电解法制备了未见文献报道的杂多蓝H8[SiMo11Co(H2O)O39]·20H2O,通过X-射线衍射测定了其晶体结构,该晶体属单斜晶系,空间群P21;。晶胞参数全矩阵最小二乘法修正至中心原子Si与4个氧形成四面体结构,配原子M(M=11/12Mo+1/12Co)与O形成12个MO6八面体结构3个MO6共边形成4个M3O13三金属簇,4个三金属簇与SiO4四面体共角相连形成阴离子结构。
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本文生长出了K2Ln(NO3)5.2H2O(Ln=La;Ce;Pr;Nd;Sm)的单晶,并对其进行了晶体结构及差热-热重分析研究.结果表明,K2Ln(NO3)5.2H2O(Ln=La;Ce;Pr;Nd)的晶体属正交晶系,Fdd2空间群.首次生长出KPrN单晶并用直接法解出其晶体结构.解得KPrN的晶胞参数为:a=11.2210(10),b=21.411(3),c=12.208(2),Z=6;R=0.0240.对KLnN加热,则依次出现脱水、熔化、不可逆相变和NO的分解过程(K2Ce(NO3)5·2H2O除外)K2Ln(NO3)5·2H2O(Ln=La;Nd;Sm)的NO分三步分解,K2Ln(NO3)5·2H。O(Ln=Ce;Pr)的NO分两步分解·KNO3和Ln(NO3)3·nH2O的混合物在225℃左右生成K2Ln(NO3)5
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用十二烷基胺代替传统的季铵盐合成了中孔全硅分子筛HMS,并将硅钨杂多酸(SiW12)浸渍固载在HMS上.用XRD,FT-IR以及NH3-TPD等手段对HMS及不同负载量和焙烧温度的负载催化剂进行了表征.即使在固载量为50%的SiW12/HMS中,SiW12仍保持其Keggin结构并均匀分布在载体表面上,没有SiW12晶相生成.同时,在气-固相反应体系中研究了固载在HMS上的SiW12在合成乙酸丁酯中的催化性能.实验结果表明,200℃焙烧可以增强杂多酸与HMS内表面之间的相互作用,从而使其对酯化反应活性具有一定的影响,并且固载催化剂在较低反应温度下具有较高的酯化活性,且性能稳定,有一定的应用前景.
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研究了60,80,100,120目等4种精细胶粉(FRP)的基本性能及其在胎面胶中的应用。结果表明,随FRP精细化程度增加,掺用50份FRP后NR硫化胶的拉伸强度和扯断伸长率均有所提高;NR/BR并用胎面胶混炼胶的门尼粘度降低,胶料流动性增加,挤出物外观等级提高;NR/BR共混硫化胶的拉伸强度、扯断伸长率及热空气老化系数提高,撕裂强度和邵尔A型硬度有所下降,而生热、动态疲劳和磨耗量等均在80~100目处出现最佳值。随着FRP用量的增加,NR/BR硫化胶的拉伸强度、撕裂强度和弹性降低,生热增加,动态疲劳和热空气老化性能则有所改善。
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Four types of sensitized luminescence of Dy3+ are reported: (1) by a host having a broad-band spectrum as in Na3Y0.99Dy0.01(VO4)(2); (2) by a sensitizer having a broad-band spectrum as in Ca2B2O5:Dy3+, Bi3+; (3) by a sensitizer having a narrow-band spectrum as in Mg2Gd7.9Dy0.1(SiO4)(6)O-2; (4) by a sensitizer having a broad-band spectrum and energy migration as in Gd compounds such as Ca1.96Pb0.04Gd7.9Dy0.1(SiO4)(6)O-2. The luminescent intensity of Dy3+ can be enhanced in these ways.
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In this paper, the luminescence properties of Eu3+ and Dy3+ in the oxyapatites M(2)RE(8)(SiO4)(6)O-2 (M=Mg, Ca; RE=Y, Gd, La) were studied. The spectral characters of Eu3+ were discussed in relation to the crystal structure. The dependence of the red-to-orange intensity ratio and the position of the charge transfer band of Eu3+ and the yellow-to-blue intensity ratio of Dy3+ together with their fluorescence intensities (I-R for Eu3+ and I-Y for Dy3+) On the M(2+) and the substitution of BO45- and PO43- for SiO44- was discussed. Finally, the concentration quenching of Dy3+ luminescence was reported.
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The voltammetric behavior of cytochrome c entrapped in hydrogel membranes at paraffin wax-impregnated spectroscopic graphite electrodes (WISGE) was studied in this paper. A pair of well-defined peaks appeared at +70 mV (vs. Ag/AgCl). Beside these two peaks, another pair of peaks emerged at around +225 mV. Further investigations suggested that at least three states of cytochrome c existed in the membranes due to the special structure of the hydrogel. The native conformation of cytochrome c molecules was stabilized by the hydrophilic environment that was formed by the hydroxyl structure of the membranes and facilitated the cytochrome c electron transfer reaction at +70 mV. The molecules directly adsorbed on the surface of the graphite electrode were responsible for the redox peaks at around +225 mV. Whether the adsorption peaks were detectable or not was related to the thickness of membranes and the pre-retaining time before the formation of membranes.
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Phenolphthalein poly(ether ketone) (PEK-C) was tested using an instrumented impact tester to determine the temperature effect on the fracture toughness K-c and critical strain energy release rate G(c). Two different mechanisms, namely the relaxation processes and thermal blunting of the crack tip were used to explain the temperature effect on the fracture toughness. Examination of the fracture surfaces revealed the presence of crack growth bands. It is suggested that these bands are the consequence of variations in crack growth along crazes that are formed in the crack tip stress field. As the crack propagates, the stress is relaxed locally, decreasing the growth rate allowing a new bundle of crazes to nucleate along which the crack advances.
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Fracture toughness values of phenolphthalein poly(ether ketone) (PEK-C) at 190 degrees C were determined by two different methods, i. e. the conventional crack growth method and the crack stress whitening zone method, which show consistent results. This indicates that the crack stress whitening zone method can be used to determine the crack initiation of some polymers for which the blunting line concept is unsuitable.
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合成了x值不同的La_(2-x)Sr_xCoO_4±λ(x=0~2)系列复合氧化物.用XRD研究了这一系列氧化物的晶体结构,结果表明x在0.25~1.5之间可形成具有K_2NiF_4结构的复合氧化物.用化学分析方法测定了过渡金属Co的价态和±λ含量与x值的关系.用IR,TPD,TPR,XPS,SEM等方法研究了这类复合氧化物的氧化还原性能,所含不同氧种,考察了对CH_4,CO的完全氧化活性,并对其活性与化学组成及结构间的关系进行了讨论.