A refined double integral method has been applied to the problem encountered in the diffu-sion release of a drug from a polymeric matrix.The finite external mass transfer resistance has alsobeen incorporated into the ...A refined double integral method has been applied to the problem encountered in the diffu-sion release of a drug from a polymeric matrix.The finite external mass transfer resistance has alsobeen incorporated into the present analysis.Experimental release rates of 5-fluorouracil fromethylene-vinyl alcohol copolymer into distilled water were measured in order to test the applicabilityof these models.All system parameters were measured by experiments and models were built up.Themodels presented here are much more accurate than Higuchi model and much easier than the exactsolutions.In view of accuracy,the models are almost the same as the exact solutions.The experi-mental release data agree Well with the computed展开更多
目的研究正常肝脏扩散峰度成像（DKI）的可行性及参数测量的可重复性。方法使用飞利浦1.5 T MR扫描仪和相同的序列及参数,对35名年轻志愿者进行2次肝脏DKI扫描,生成平均扩散系数（MD）图和平均峰度系数（MK）图。在左、右肝内分别选取...目的研究正常肝脏扩散峰度成像（DKI）的可行性及参数测量的可重复性。方法使用飞利浦1.5 T MR扫描仪和相同的序列及参数,对35名年轻志愿者进行2次肝脏DKI扫描,生成平均扩散系数（MD）图和平均峰度系数（MK）图。在左、右肝内分别选取上、中、下3个代表性层面的左、中、右9个测量位置,每个位置放置大小相同的感兴趣区（ROI）,分别测量并比较各ROI的MD值和MK值及左、右肝各9个ROI的平均参数值,并评估各参数测量的可重复性。结果前后2次DKI扫描b=800 s/mm2图像上肝脏的信噪比（SNR）较好,差异无统计学意义（P〉0.05）。2次扫描左、右肝内不同测量部位的MD、MK值差异均无统计学意义（P〉0.05）,其中右肝中层及左肝下层的MD、MK值可重复性较好。左肝的平均MD值、MK值较右肝高（t=-5.665～8.095,P〈0.001）,但左肝的平均MD、MK值可重复性均较右肝差;MD值、MK值的可重复性相近。结论初步研究结果表明,正常肝脏DKI是可行的,右肝中层和左肝下层的MD、MK值的可重复性较好;左肝的平均MD、MK值较右肝高,但可重复性较右肝差,MD、MK值的可重复性相似。展开更多
文摘A refined double integral method has been applied to the problem encountered in the diffu-sion release of a drug from a polymeric matrix.The finite external mass transfer resistance has alsobeen incorporated into the present analysis.Experimental release rates of 5-fluorouracil fromethylene-vinyl alcohol copolymer into distilled water were measured in order to test the applicabilityof these models.All system parameters were measured by experiments and models were built up.Themodels presented here are much more accurate than Higuchi model and much easier than the exactsolutions.In view of accuracy,the models are almost the same as the exact solutions.The experi-mental release data agree Well with the computed
文摘目的研究正常肝脏扩散峰度成像（DKI）的可行性及参数测量的可重复性。方法使用飞利浦1.5 T MR扫描仪和相同的序列及参数,对35名年轻志愿者进行2次肝脏DKI扫描,生成平均扩散系数（MD）图和平均峰度系数（MK）图。在左、右肝内分别选取上、中、下3个代表性层面的左、中、右9个测量位置,每个位置放置大小相同的感兴趣区（ROI）,分别测量并比较各ROI的MD值和MK值及左、右肝各9个ROI的平均参数值,并评估各参数测量的可重复性。结果前后2次DKI扫描b=800 s/mm2图像上肝脏的信噪比（SNR）较好,差异无统计学意义（P〉0.05）。2次扫描左、右肝内不同测量部位的MD、MK值差异均无统计学意义（P〉0.05）,其中右肝中层及左肝下层的MD、MK值可重复性较好。左肝的平均MD值、MK值较右肝高（t=-5.665～8.095,P〈0.001）,但左肝的平均MD、MK值可重复性均较右肝差;MD值、MK值的可重复性相近。结论初步研究结果表明,正常肝脏DKI是可行的,右肝中层和左肝下层的MD、MK值的可重复性较好;左肝的平均MD、MK值较右肝高,但可重复性较右肝差,MD、MK值的可重复性相似。
