279 resultados para 367.224


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常规方法合成的非AB_5型镍-稀土金属间化合物不是单相化合物,都是多相混合物,而作为高容量的MH-Ni电池负极材料,多相混合物是有益的.对非 AB_5型的镍-稀土金属间化合物作为MH-Ni电池负极进行了电化学性能研究,结果表明:室温下最大放电容量为298mAh/g,经46次循环,容量保持基本不变;在-25~0C以下至-40~0C,其放电容量远高于AB_5型的合金.虽然负极的放电容量都是随温度降低和放电电流的增大而降低,但即使在 -40~0C,I_c=145 mA/g的高电流下,非AB_5型镍-稀土金属间化合物的放电容量仍达到158 mAh/g,而AB_5型的放电容量只有8.8mAh/g.提出合成低温负极材料的3条经验原则.

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目的: 分析测定长白山白眉蝮蛇蛇毒纤溶酶和磷脂酶A2 的分子量和纯度。方法与结果: 应用MALDI/TOF MS法测定纤溶酶的分子量为23333±90,磷脂酶A2的分子量为14000±20,相对偏差在0138%以内。结论: 应用此方法未检测到杂蛋白质谱峰的存在, 酶的纯度较好, 测得结果要比电泳法准确。MALDI/TOF MS提供了一种测定蛋白质药物纯度快速准确的新方法。

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本文采用水溶液中生长晶体的方法合成了KLnN(Ln=Pr,Nd)的单晶,研究了KPrN的单晶结构及KLnN(Ln=Pr,Nd)的非线性光学性质。KLnN(Ln=Pr,Nd)均属正交晶系,Fdd2空间群。KPrN的晶胞参数为:a=2.1411(3)nm,b=1.12210(10)nm,c=1.2208(2)nm,Z=6,R=0.0240.KLnN(Ln=Pr,Nd)的二次谐波光强与KLnN(Ln=La,Ce)处于同样的数量级.KLnN容易生长出大尺寸晶体,是一类有应用前景的可产生蓝绿光的倍频转换材料。

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用导电炭黑(CSF)作填充剂,研究了它对NBR混炼胶加工行为、硫化特性、硫化胶性能及导电性能的影响,并与填充乙炔炭黑(ACET)的NBR胶料性能进行了对比。结果表明,随着CSF用量增加,炭黑结合NBR含量、门尼粘度、屈服强度和拉伸强度均增加,而扯断伸长率及挤出物出口膨胀比降低,挤出物外观变优;随着CSF用量增加,焦烧和正硫化延长,硫化速度及硫化胶强度有所下降,而导电性能变优。硫化胶体积电阻率随硫化时间延长及施加负荷增加而降低,随温度升高和增塑剂邻苯二甲酸二辛酯用量增加而升高。同时表明,NBR/CSF体系的结合NBR含量、门尼粘度、混炼胶应力-应变性能及硫化胶导电性能等均高于NBR/ACET体系。

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用动态法研究了聚乙烯醇胺肟(PVAAO)螯合纤维对钯的吸附。讨论了影响吸附率和回收率的因素,确定了最隹吸附条件。用5%硫脲+0.50mol/L硝酸溶液可以解吸。PVAAO螯合纤维对钯的饱和吸附容量为451.9mg/g干纤维。

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Europium (II) and europium (III) have been observed in MMgF(4):xEu, yTb (M=Ca, Sr, Ba) phosphors using their typical photoluminescence spectra when are synthesized in Ar or an Ar/H-2 stream. The valence state of Eu is influenced by terbium. It is notable that the intensities of the electron spin resonance peaks corresponding to Eu2+ change in a regular way when terbium ions are incorporated which can be explained by an electron transfer mechanism.

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合成了铕离子激活的MMgF4.磷光体,研究了Eu3+离子的光谱特征与基质化合物的关系,存在三类发光中心,讨论了基质组成对铕离子价态的影响。

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用低硒(Se)、低维生素E(VE)的克山病病区粮喂养大鼠11周,血浆和心肌白三烯(LTC4)水平上升,心肌自由基净含量增加,血清和心肌脂质过氧化物(LPO)浓度增高,而全血和心肌谷胱甘肽过氧化物酶(GSH-Px)活力下降;补Se、VE或Se+VE可明显降低大鼠LTC4水平及自由基和LPO浓度,除补VE组外均可提高GSH-Px活力。提示:食物中Se与VE不足影响花生四烯酸代谢中脂氧合酶的活力及Se与VE不足生成的过量自由基和LPO促进LTC4合成,可能参与克山病缺血缺氧性心肌损害的发生发展过程.

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The phosphors MMgF(4)(M = Ca, Sr, Ba) doped with samarium ions are synthesized in different atmospheres using solid phase reaction at high temperature. Samarium has been first stabilized in the divalent state in SrMgF4 and BaMgF4 matrices. Effects of matrices on the valent state of samarium ions are briefly discussed.

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A valence change from RE3+ to RE2+ (RE=Eu, Sm, Yb) was observed in samples of SrB4O7: RE prepared by solid state reaction at high temperature in air. The phosphors SrB4O7: RE2+ show efficient luminescence at room temperature. The broad band d-f emissions of Eu2+ and Yb2+ are at 367 and 360 nm respectively. The sharp line f-f emissions of the Sm2+ ion (5D0-F-7(J)) are in the range 680-780 nm. The probable reasons for the valence change of Eu, Sm and Yb in this host are discussed.

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Reaction of 1,3-cyclohexadiene(tricarbonyl)iron (1) with ortho-substituted aryllithium reagents ArLi (Ar=o-CH3C6H4, o-CH3OC6H4, o-CF3C6H4) in ether at low temperature, and subsequent alkylation of the acylmetalates formed with Et3OBF4 in aqueous solution at 0-degrees-C or in CH2Cl2 at -60-degrees-C gave the 1,3-cyclohexadiene(dicarbonyl)[ethoxy(aryl)carbene]iron complexes (eta4-C6H8)(CO)2FeC(OC2H5)Ar (3, Ar = o-CH3C6H4; 4, Ar = o-CH3OC6H4), and the isomerized product (eta3-C6H8)(CO)2FeC(OC2H5)C6H4CF3-o (5), respectively, among which the structure of 3 has been established by an X-ray diffraction study. Complex 3 is monoclinic, space group P2(1) with a = 8.118(4), b = 7.367(4), c = 14.002(6) angstrom, beta = 104.09(3)-degrees, V = 812.2(6) angstrom3, Z = 2, D(c) = 1.39 g cm-3, R = 0.056, and R(w) = 0.062 for 976 observed reflections. Complexes 3 and 5 were converted into the chelated allyliron phosphine adducts(eta3-C6H8)(CO)2(PR31)FeC(OC2H5)Ar (6, Ar = o-CH3C6H4, R1 = Ph; 7, Ar = o-CH3C6H4, R1 = OPh; 9, Ar = o-CF3C6H4, R1 = Ph), by reaction with phosphines in petroleum ether at low temperatures.

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The viscosities of polystyrene-b-poly (ethylene/propylene) diblock copolymer in mixed solvent of n-octane and benzene were measured. The influences of the constitution of the mixed solvent, temperature and concentration were on the viscosity investigated. During the micellization the solution viscosity increases rapidly. The results are consistent with the study on the micellization by light scattering. The average mass of micelleswas measured and the hydrodynamic radius of gyrations were calculated.

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用粘度法主要研究了聚苯乙烯和氢化异戊二烯二嵌段共聚物在选择性溶剂中的粘度行为,并计算得到其流体力学半径.测得在胶束化过程中溶液粘度出现异常变化,溶液在胶束化时粘度迅速增大,并与用光散射法研究共聚物溶液胶束化过程得封的结果相比较.

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考察了10种常用拓扑指数与烷烃辛烷值的相关关系,探讨了结构排序法预测烷烃辛烷值的变化趋势及其分布规律。

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The half-open vanadocene, V[2,4-(CH3)2C5H5](C5H5)CO, was obtained by the reaction of V[2,4-(CH3)2C5H5](C5H5)PMe3 with CO in petroleum ether at room temperature. Its crystal structure was determined by X-ray diffraction technique. The crystal was monoclinic with space group P2(1)/n, a = 16.614(3), b = 7.636(1), c = 19.128(6) angstrom, beta = 99.92(2)-degrees, V = 2390.5(9) angstrom3, and Z = 8. The final R value was 0.043. The V(1)-CPD(1) (half) (PD = 2,4-(CH3)2C5H5) bonds were shorter (0.038 angstrom) than the V(1)-CCP(1) (half) (CP = C5H5) bonds, averaging 2.224(4) versus 2.262(4) angstrom, respectively. 4V[2,4-(CH3)2C5H5](C5H5)CO has been characterized by IR and EPR methods.