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Macromolecular ligands with liver-targeting group (pyridoxamine, PM) PHEA-DTPA-PM and PAEA-DTPA-PM were prepared by the incorporation of different amount of diethylenetria-minepentaacetic acid monopyridoxamine group (DTPA-PM) into poly-cc, p-[N-(2-hydroxyethyl)-L-aspartamide] (PHEA) and poly-α, β-[N-(2-aminoethyl)-L-aspartamide] (PAEA). The macromolecular ligands thus obtained were further complexed with gadolinium chloride to give macromolecular MRI contrast agents with different Gd(Ⅲ) contents. These macromolecular ligands and their gadolinium complexes were characterized by 1H NMR, 1R, UV and elementary analysis. Relaxivity studies showed that these polyaspartamide gadolinium complexes possess higher relaxation effectiveness than that of the clinically used Gd-DTPA. Magnetic resonance imaging of the liver in rats and experimental data of biodistribution in mice indicate that these macromolecular MRI contrast agents containing pyridoxamine exhibit liver-targeting property. 相似文献
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We observed the NMR signal of low-pressure gas 129Xe by laser enhanced method on an MSL-400 NMR spectrometer and measured nuclear spin relaxations of 129Xe gas at various temperatures. The relaxation rate constant of 129Xe-133Cs spin exchange was obtained as (6.8±0.5)×10-16cm-3s-1. 相似文献
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人脑初级视皮层内事件相关型视觉刺激fMRI BOLD响应特性初步研究 总被引:1,自引:0,他引:1
基于脑血氧水平依赖(BOLD)对比的功能磁共振成像(fMRI)方法是研究脑功能活动的一种重要的无损伤探测手段,BOLD的机制及它与脑神经活动关系一直是国际上十分活跃的研究领域,尤其是在实验研究方面. 视觉刺激所引起的脑的初级视皮层(V1) 的BOLD响应的时间特性已有较多的研究,但是在这些研究中,有的结论认为BOLD对视觉刺激的响应是线性的,有的结论却是相反的. 我们采用事件关联型核磁共振功能成像(ER-fMRI)方法,研究不同的短暂视觉刺激持续时间下的BOLD响应,得到了视觉刺激下的脑激活图. 同时找出了视觉刺激时间分别是1、2、3、4、5和6 s的V1区的BOLD响应曲线,并初步显示出BOLD响应与刺激持续时间的线性关系. 相似文献
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报道了用MRI中STEAM方法获得定域谱(MRS)的实验结果,用相位正交、时间一长一短的二个特形脉冲对水峰进行预饱和照射,得到抑制水峰的MRS.这种方法抑制水峰的效果比用梯度散相压水峰的效果好。对于三种常见的特形脉冲,用GAUSS脉冲得到效果最好的实验结果。 相似文献
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The DNP-enhanced NMR experiment was performed on the DBF samples doped with free radicals. The experimental results show that it becomes very easy to perform the complicate NMR experiments under DNP enhancement. For the sample whose spin lattice relaxation is very slow, if it is doped with appropriate quantity free radicals. 相似文献
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γ辐照聚合物的^13C—NMR研究 总被引:1,自引:0,他引:1
用固体高分辨^13CNMR方法分别研究了聚乙烯(PE)、聚丙烯(PP)、聚氯乙烯(PVC)的辐射化学反应机理和辐射变色的临界剂量,讨论了其辐射化学稳定性与结构的关系。 相似文献
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应用磁共振成像(MRI)和质子定域波谱(1H-MRS)对强直流电刺激大鼠基树突区诱发慢性颞叶癫痫模型进行研究. MRI实验表明: 随着强直流电刺激时间的延长,在T2加权像(T2-MRI)中,模型大鼠的海马区腹、中侧区单侧或双侧,呈现异常高信号,扩散加权像(DWI)信号呈低信号,质子密度像无明显改变,表明T2值和表观扩散系数(ADC) 值较大的自由水比例增大. 磁共振波谱实验发现:模型大鼠T2-MRI中信号异常区与其对侧区的1H-MRS相比,NAA,PCr(包括Cr)和Cho的峰面积均无显著改变,表明在慢性颞叶癫痫模型早期1H-MRS不能检测到神经元损伤或死亡. 相似文献