985 resultados para Cao, Xueqin, ca. 1717-1763.


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研究了镧、轧、镱及四种配合物对Ca~(2+)-ATP酶活性的影响.结果表明,低浓度的La~(3+),Gd~(3+)和Yb~(3+)对肌质网Ca~(2+)-ATP酶有激活作用;随着其浓度的增加,它们对酶活性的抑制程度增大;而La~(3+),Gd~(3+)和Yb~(3+)对纯化的Ca2~(+)-ATP酶则只有抑制作用;Gd─N─乙酰─缬氨酸和Yb─丙氨酰代丙氨酸配合物对肌质网膜和纯化的Ca~(2+)-ATP酶活性的影响与Gd~(3+)及Yb~(3+)类似,但其激活程度和抑制程度比Gd~(3+)及Yb~(3+)小;Gd─DTPA和Yb-DTPA对Ca2~(+)-ATP酶活性基本无影响。

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研究了稀土离子对肌质网(Ca~(2+)+MG~(2+))-ATP酶活性的影响及其作用机制,结果表明,低浓度Gd~(3+)对肌质网膜上(Ca~(2+)+Mg~(2+)),ATP酶有激活作用,较高浓度Gd~(3+)抑制其活性,Gd~(3+)抑制纯化酶的活性,低浓度Gd~(3+)对磷脂酸(FA)、心磷脂(CL)重组酶有激活作用,而对磷脂酰胆碱(PC)、磷脂酰胆碱(PC)与磷脂酰乙醇胺(Pe)混合物(PC/PE)及磷脂酰丝氨酸(PS)重组酶无激活作用,低浓度Tb~(3+)对肌质网膜与纯化酶上Ca~(2+)结合位点的影响不同。

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Alkaline earth (Mg, Ca. Sr) yttrium silicate oxyapatites doped with Eu3+ show red luminescence with comparable intensity. In this system of phosphors, the Eu3+ ions enter 4f sites and 6h sites simultaneously according to the fluorescence spectra, in which

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近年,水溶性非离子化的稀土配合物由于可用作潜在的NMR造影剂而受到重视,特别是热力学和动力学均稳定的Gd(Hp-DO3A)和Gd(DTPA-BMA)已应用于临床医学诊断。前文报导了新螯合剂—氨三乙氧基乙酸(NTEA)的合成及其La配台物单晶的结构分析。

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采用固相反应的方法;经二次灼烧合成了掺Ce(3+)、Tb(3+)的Ca3Y2(BO3)4和Sr3Y2(BO3)4磷光体;分析了合成过程中铈的还原情况.用X-射线衍射分析确定了它们的结构均为正交晶系,空间群P21cn测定了Ce(3+)和Tb(3+)在两种基质中的光谱,得到Ce(3+)波长位移的某些规律,观察到Ce(3+)对Tb(3+)的敏化作用.

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以Mg(NO3)2、Ca(NO3)2、Eu(NO3)3、Bi(NO3)3、LiNO3和Si(OC2H5)4为反应物,采用溶胶-凝胶法,在比较低的温度下,首次合成0.701moIMgO-0.175molCaO-1.25moISiO2∶0.06molEu(3+),0.002moIBi(3+)(加入Li+作为电荷补偿剂)发光体。得到了最佳合成条件。研究了由溶胶向凝胶转变和凝胶向发光晶体的转变过程。探讨了发光体在不同激发波长激发下的发光特性以及在激活剂、敏化剂不同掺杂量下的发光行为。讨论了在(Mg(a)O-SiO2基质中Bi(3+)对Eu(3+)的能量传递和敏化作用。

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用固相法首次合成了NdSr_(1-x)M_xNiO_4(M=Ca:0.0≤1.0;M=Ba:0.0≤x≤0.6)系列复合氧化物,并研究了其结构,红外光谱,电学性质和磁学性质。除NdCaNiO以正交晶系结晶外,其它试样的结构均属于四方晶系。IR谱显示随Ca ̄(2+)离子含量的增加,NdSr_(1-x)M_xNiO_4的Ni-O键缩短,Ca ̄(2+)和Ba ̄(2+)引入NdSrNiO_4以取代Sr ̄(2+),使试样由金属性导电转变为半导体性导电;随Ca ̄(2+)含量增加,试样的室温电阻率增大。77~300K磁化率与温度关系曲线显示,所有试样的Ni ̄(3+)都以低自旋状态存在。

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高温固相反应合成了钐离子激活的MF_2-MgF_2磷光体,考察了合成条件及基质组成对钐离子价态的影响,并讨论了荧光光谱与基质及钐离子价态间的关系.

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制备了一种新的固溶体La_(2-x)Ca_xNiO_4(0≤x≤1.4)并与固溶体La_(2-x)Sr_xNiO_4作了对比。它们都具有四方的K_2NiF_4结构,其晶胞参数和晶胞体积都随x的增加而减少。固溶体La_(2-x)Ca_xNiO_4的室温电阻率随x的增加而增加,而固溶体La_(2-x)Sr_xNiO_4的室温电阻率却随x增加而减小,这种电学性质上的差别可能是由于Sr或Ca杂后引起Ni的价态变化导致Ni~(3+)的电子构型转变而造成的。

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检测10种外眼病141例、178眼泪液中的CaMg、Zn、Fe含量。结果显示,翼状胬肉和泡性角结膜炎泪液中的Ca,复发单疱病毒性角膜炎(HSK)泪液中的CaMg、Zn、Fe,慢性结膜炎泪液中的CaFe含量均明显低于对照组(P<0.001~0.05)。提示这4种外眼病的病因可能与泪液CaMg、Zn、Fe含量不足有关。

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讨论了MeBeF_4基质中钐离子的光谱及价态.还原气氛中仅在SrBeF_4和BaBeF_4中观察到了Sm~(2+)的发射.

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In this paper, the luminescence properties of Dy3+ and Eu3+ in M3Ln2 (BO3)4 (M = Ca,Sr,Ba; Ln = La, Gd, Y) were systematically studied. The hypersensitive transitions of Dy3+ and Eu3+ were investigated in relation to the host compositions; the relationship between the energy of Eu3+ charge-transfer band and M2+ ion was discussed, and the concentration quenching of Dy3+ luminescence was reported.

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The system of Ca-Sr-Cu-O have been investigated. Two new compounds with compositions Sr3Cu5O8+alpha and CaSrCu3O5+alpha have been discovered. Both are orthorhombic with a = 6.489, b = 11.280, c = 12.240 angstrom for CaSrCu3O5+alpha and a = 3.950, b = 11.479, c = 13.420 angstrom for Sr3Cu5O8+alpha. The X-ray powder data for CaSrCu3O5+alpha, Sr3Cu5O8+alpha, Sr2CuO3 and SrCuO2 are presented. The oxidation state of Cu ion and oxygen contents are analyzed by iodometric titration. Sr0.5Ca0.5CuO2 that has a similar structure with SrCuO2 has been found and its X-ray data are presented also.

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通过对含有 Si,Ca 等非稀土杂质的 YBa_2Cu_3O_(7-δ)氧化物超导体的 J_c,T_c测量、X 射线粉末衍射和扫描电镜等微结构分析、热重分析和热机械分析铜价态和氧含量的化学分析以及材料稳定性的测试等,发现杂质 Ca 有利于提高材料的 J_c,增强其结构质点间的怍用力,降低材料在空气中的失氧量,提高稳定性;杂质Si 的作用则与 Ca 的作用相反。