排序方式: 共有93条查询结果,搜索用时 15 毫秒
31.
32.
In order to improve the cancer-targeting and selective activity of antineoplastic agent [5-fluorouracil (5-FU)], a novel pH-responsive drug delivery system [pullulan acetate/sulfonamide (PA/SDM) conjugate] was synthesized by a diafiltration method. Sulfonamide was grafted to the hydrophobicaUy modified pullulan acetate to enhance the pH sensitivity for better cancer-targeting delivery. 5-FU was loaded into the self-assembled nanoparticles by the same method. The drug-loaded self-assembled nanoparticles were successfully obtained and characterized in terms of particle size, morphology and drug loading and release profile at various pHs. The results showed that the mean diameter of the self-assembled particles was approximately 100nm, with uniform size and good spherical morphology. The nanoparticles showed good stability at pH 7.4, which is equal to that of the normal body fluid, but shrank and aggregated below pH 6.8, which is close to the pH with tumors. The loading efficiency and concentration of released 5-FU was monitored at 269 nm on the UVNis spectrophotometer. The release profile was heavily pH-dependent around phvsiological pH, and the release rate was significantly enhanced under pH of 6.8. 相似文献
33.
34.
35.
A two-compartment model of patient-artificial kidney system consisting of a cerebrospinalfluid(CSF)and a body liquor compartments have been presented.With the model,the mechanism ofdisequilibrium syndrome occurred in a patient undergoing hemodialysis has been discussed to simulatethe CSF pressure transients.Urea,as an uretic toxin,was injected into dogs and in vivohemodialysis experiments have been performed under clinical conditions.The parameters in the sol-ution,G and K,have been determinde from experiments and are in good agreement with those re-ported under normal physiological conditions and in previous investigations. 相似文献
36.
37.
在液相培养基中将米曲霉菌体培养成直径为 1~ 2mm的菌球 ,以甲醛为交联剂、明胶为活性保护剂对其进行固定化研究 .在正交实验L16(45)的基础上 ,利用人工神经网络得到了较优的固定化条件 :菌体与固定液的用量比 (固液比 ) 1∶8,固定液中含明胶 5 g·L-1、甲醛 5 g·L-1,固定化时间为 1.5h .在此条件下制备的固定化米曲霉菌体比酶活为 15 0 0U ,比酶活保留率 83% .对固定化米曲霉菌体稳定性进行深入研究表明 ,其最适反应温度和 pH值分别为 6 3℃和 8.0 ,与游离菌体相比最适反应条件范围变宽 .在固定床反应器中用其连续拆分N -乙酰 -DL -丙氨酸 ,半衰期为 77天 ,具有较高的操作稳定性 相似文献
38.
超细Co/Ti02和Ce/Ti02的制备及光催化性能 总被引:3,自引:0,他引:3
以四氯化钛为原料、硝酸钴或硝酸铈为掺杂剂,以共沉淀或机械混合的掺杂方法制备了掺杂的Co/Ti02和Ce/Ti02超细粉体,并进行了x射线衍射表征和光催化活性评价。掺杂抑制了样品晶粒的长大,在500℃焙烧温度下,掺钴样品的平均粒径由未掺杂纯样品的47.7nm减小到了12.1nm(机械混合)和9.6nm(共沉淀),掺铈样品的平均粒径则分别减小到33.1nm和16nm;钴掺杂导致了样品在焙烧温度500℃时便有金红石相出现,而铈掺杂的样品和纯样品在相同温度下没有金红石相;通过甲苯在样品上的光催化氧化过程,证实了掺杂对样品的光催化性能有影响。在纯样品和掺钴、掺铈的样品上,140min后甲苯的质量浓度由初始的100mg/m^3分别下降到17、2.3和7.3mg/m^3;甲苯在实验条件下的光催化氧化符合一级动力学规律。 相似文献
39.
40.
引 言体外血液解毒广泛应用于治疗由内生或外源性毒物引起的各种疾病 ,如药物中毒、肝或肾衰竭、代谢紊乱等 .对于从血液中清除亲水性毒物 (如尿素、肌酐等 ) ,临床上已有血液透析、血液超滤等多种方法 .但对于血液中的亲脂性毒物 ,由于其与蛋白分子强烈地结合 ,采用上述常规方法很难清除 .虽然血液灌流或血浆交换可以部分除去与蛋白结合的毒物分子 ,然而也会除去甲状腺激素、类固醇激素等多种对人体有用的物质[1].Brunner等[2 ]曾通过在多孔膜中填充石蜡的方法提高膜的亲脂性能 ,然而此种膜只能使少量游离毒物分子通过 ,远不能满足… 相似文献