电中性的GdDTPA双酰胺衍生物作为MRI造影剂

1988年德国卫生局批准(NMG)_2[Gd(DTPA)·H_2O]可作为 MRI 造影剂临床应用(商品名为 Magnevist),NMG 为 N-甲基葡萄糖胺根。从药物动力学角度看,Gd(DTPA)具有弛豫性强、毒性小、细胞外分布、不通过正常的血脑屏障、迅速由肾脏排出、在人体内结构稳定、具有高溶解度等特征。Gd(DTPA)对中枢神经系统病变增强效果良好,但是组织分布无特异性,对腹部器官如肝脏、脾脏的成像效果较差。为了改善其器官选择性,而且使生物体更易接受,减少毒副作用,人们在电中性的 GdDTPA 衍生物方面作了许多努力。

Hydrothermal synthesis and crystal structure of sandwich-like heteropolymolybdophosphates

Sandwich-like heteropoly molybdochromophosphates of supermolecular compound [NH3(CH2)(6)NH3](2)H-3{Cr[Mo6O15(HPO4)(H2PO4)(3)](2)}. 4H(2)O has been hydrothermally synthesized and the single crystal structure has been determined by X-ray diffraction. The crystal data are has follows: triclinic, space group P (1) over bar a=12.156(2), b=12.809(3), c=13.530(3) Angstrom, alpha=102.46(3)degrees, beta=93.67(3)degrees, gamma=93.46(3)degrees, V=2046.9(7) Angstrom(3), Z=1, M-r=2768.69, D-c=2.246 g/cm(-3), F(000)=1337, mu=2.162 mm(-1). The structure has been refined to R=0.0666 and wR=0.1745 by full-matrix least-squares method. The title compound is composed of 1, 6-diaminohexane, water molecules, and {Cr[Mo6O15(HPO4)(H2PO4)(3)](2)}(7-) anion which consists of six oxygen atoms from two [Mo6P4] units with a sandwich-like transition metal atom Cr located at the center of symmetry.

Calculation of second-order nonlinear optical coefficients of KTiOPO4 and KTiOAsO4

The second-order nonlinear optical tensor coefficients of both KTiOPO4 (KTP) and KTiOAsO4 (KTA) are calculated from the chemical bond viewpoint. All constituent chemical bonds of both crystals are considered, and contributions of each type of bond to the total linearity and nonlinearity are determined. Calculated results agree satisfactorily with experimental data in both signs and numerical values. The calculation shows that though TiO6 groups and P(1)O-4 or As(1)O-4 groups have relatively larger linear contributions, they can only produce an advantageous environment for KOx (x = 8, 9) groups and P(2)O-4 or As(2)O-4 groups in nonlinear optical contributions. The origin of nonlinearity of KTP family crystals comes from the KOx (x = 8, 9) and P(2)O-4 groups in their crystal structures. Furthermore, the difference in optical nonlinearities of KTP type crystals is analyzed, based on the detailed calculation of nonlinearities of both KTP and KTA. (C) 1999 Academic Press.

用仪器化冲击仪研究HIPS/SBS共混物的冲击性能

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

电化学石英晶体微天平研究六氰亚铁铜膜修饰电极及其离子效应

利用电化学石英晶体微天平（EQCM）手段，结合循环伏安法．计时电流法对六氰亚铁铜（CuHCF)膜修饰电极及其在不同水溶液中的离子交换机制进行了研究。结果表明；通过循环伏安法，在Pt电极上可以牢固地形成CuHCF膜．在氧化还原过程中，不仅是阳离子，阴离子也参与了在CuHCF膜中的传输。

辐照聚酰胺1010的后效应

用ＤＳＣ以及凝胶含量测定的方法研究了辐照聚酰胺１０１０的后效应，讨论了晶区分子运动与转变受辐射后效应的影响，也探讨了结晶表面积对后效应的影响。结果表明辐射后效应主要来源于结晶表面内的俘陷自由基。

不同共混比Ln-BR/NR的性能

研究了稀土顺丁橡胶(Ln—BR)与天然橡胶(NR)以不同比例共混后生胶、混炼胶和硫化胶的性能,并与相同条件下的镍系顺丁橡胶(Ni-BR)/NR共混胶的性能进行了对比.结果表明,共混胶随Ln—BR用量的增大,ML_(1+4)~(100℃)降低,工艺行为良好,硫化胶力学性能、磨耗、湿滑指数和生热值下降,并且Ln—BR/NR硫化胶的抗湿滑性和动态疲劳性均优于Ni-BR/NR硫化胶.

ELECTROCHEMICAL REACTION OF CYTOCHROME-C AT GOLD ELECTRODES MODIFIED WITH THIOPHENE CONTAINING ONE FUNCTIONAL-GROUP

The electrochemical reactions of cytochrome c were studied at a thiophene-modified gold electrode. It was demonstrated that thiophene is an effective promoter, although there is only one functional group in the molecule. Based on this result, the mechanis

THEORETICAL-ANALYSIS OF NERNSTIAN PLOTS IN THE THIN-LAYER SPECTROPOTENTIOSTATIC TECHNIQUE

The Nernstian plots in a spectropotentiostatic experiment for complex electrode processes were studied theoretically. The plots are linear for an electron transfer process coupled with a preceding or succeeding chemical reaction, and the electron stoichio

ELECTROCHEMICAL SCANNING-TUNNELING-MICROSCOPY

An ECSTM apparatus with an ideal tip using a homemade SSX-1A STM instrument has been constructed. STM and ECSTM tips were made by electrochemical etching and insulating with paraffin, silicon rubber or epoxy resin under an optical microscope. In situ imag

吸收剂量对二甲基硅橡胶与甲基乙烯基硅橡胶分子量和凝胶含量的影响

将ＧＰＣ和特性粘数［η］测定相结合，在室温和－７８℃下，用Ｃｏ~（６０）辐射源辐照，研究了二甲基硅橡胶（ＭＱ，吸收剂量２．０５×１０~３～３．９７×１０~４Ｇｙ）和甲基乙烯基硅橡胶（ＭＶＱ，吸收剂量１０~２～１０~４）分子量和凝胶含量的变化。结果表明，辐照ＭＶＱ较辐照ＭＱ易生成凝胶，在凝胶点前的较低吸收剂量时，溶胶的分子量出现极大值，分子量分布曲线呈单峰；随吸收剂量的增加，分子量分布变窄，分子量降低；出现凝胶的吸收剂量，ＭＱ大约是ＭＶＱ的１０倍。辐照ＭＱ时，凝胶点前的溶胶的分子量分布曲线为双峰，并随吸收剂量的增加，双峰消失，分子量下降；在凝胶点时，分子量出现极大值。

PVA/PVP共混体系的非等温结晶动力学

用Mandelkern和Ziabicki理论方法求得PVA及PVA/PVP共混物结晶动力学参数Z_C和动力学结晶能力G_C值,并进行了讨论。得到的Avrami指数n不随冷却速度变化,但随非晶组分PVP的加入有所减小,加入量达百分之四十以后n由3降到2;G_C值则随非晶组分的加入而增大,当PVP加入量大于百分之三十时,G_C值不再发生明显变化。同时实验表明该高聚物及其共混体系不适合于Ozawa非等温结晶动力学方程。

IDDM患儿全血自由基和血清过氧化脂质、维生素E含量

糖尿病是一种糖能量代谢障碍性疾病。其发病率在逐年升高。有关糖尿病因及发病机制的研究一直是人们共同关注的焦点。最近自由基与糖尿病的关系引起了我们的极大兴趣。本文为我们近期所作的有关IDDM患儿全血自由基(FR)含量的研究结果,同时又测定了血清过氧化脂质(LPO)及维生素E(VE)含量,现一并报告如下

环烷酸亚铁-烷基铝-邻菲咯啉-卤化物体系催化丁二烯聚合的研究

本文研究了Fe(naph)_2(环烷酸亚铁)-Al(i-Bu)_3(三异丁基铝)-Phen(邻菲咯啉)-卤化物体系催化丁二烯聚合的一般规律。实验证实:卤化物可以提高体系的催化活性,调节聚合物的分子量,并能增加体系活性中心的稳定性;加料方式对体系的催化活性有显著的影响。催化剂的紫外-可见光谱研究表明:510nm处的吸收代表了此体系活性中心的特征吸收。