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分子扩散法捕集环境中SO_2的研究 被引量:2
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作者 张冬保 赵大为 高世东 《重庆环境科学》 1996年第6期56-60,共5页
吸收膜容量研究表明,用10%(V/V)三乙醇胺十丙酮或10%(W/V)NO2CO3作吸收剂。在15℃,绝对干燥空气条件下测得两种采样器的感度(α)。1#采样器α1(TEA)0.3043PPm·h·μg-1(S... 吸收膜容量研究表明,用10%(V/V)三乙醇胺十丙酮或10%(W/V)NO2CO3作吸收剂。在15℃,绝对干燥空气条件下测得两种采样器的感度(α)。1#采样器α1(TEA)0.3043PPm·h·μg-1(SO42-),α2(Na2CO3)0.2963ppm·h·μg-1(SO42-);2#采样器α2(TEA)0.7893PPm·h·μg-1(SO42-)α2(Na2CO3)0.8665PPm·h·μg-1(SO42-)。统计检验同种采样器的感度无显著差异。感度的温度修正为:αθ2=αθ1(θ1/θ2)β-1。式中θ为绝对温度,β=1.83或1.5。 展开更多
关键词 分子扩散法 取样器 捕集 大气监测 二氧化硫
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脑缺血区水分子扩散变化及其临床应用 被引量:4
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作者 韩鸿宾 谢敬霞 +3 位作者 付瑜 张燕 肖卫忠 谢汝萍 《北京大学学报(医学版)》 CAS CSCD 北大核心 2001年第2期109-112,共4页
目的 :研究脑缺血区水分子扩散运动变化的规律。探讨脑缺血区水分子扩散运动变化的可能机制。方法 :临床诊断脑缺血或脑梗死患者 43例 ,磁共振成像检查距起病 6h之内 10例 ,7~ 2 4h 12例 ,2~ 7d 7例 ,8~ 14d 8例 ,15d~ 2个月 6例 ,... 目的 :研究脑缺血区水分子扩散运动变化的规律。探讨脑缺血区水分子扩散运动变化的可能机制。方法 :临床诊断脑缺血或脑梗死患者 43例 ,磁共振成像检查距起病 6h之内 10例 ,7~ 2 4h 12例 ,2~ 7d 7例 ,8~ 14d 8例 ,15d~ 2个月 6例 ,计算缺血区的水分子扩散速率变化。结果 :正常脑灰质区水分子扩散速率为 8.6 1×10 -4 mm2 ·s-1。早期缺血区水分子扩散迅速下降为 (4 .72× 10 -4 +1.5 1× 10 -4 )mm2 ·s-1,与对侧相应区的比值为0 .5 5± 0 .18。随发作与检查间隔延长 ,水分子扩散速率上升 ,2~ 7d为 (5 .6 8× 10 -4 ± 1.2 2× 10 -4 )mm2 ·s-1,比值为 0 .6 6± 0 .14;8~ 14d为 (9.2 2× 10 -4 ± 2 .0 7× 10 -4 )mm2 ·s-1,比值为 1.0 7± 0 .2 4。 2个月时扩散值明显升高 ,与纯水相近 ,为 (2 6 .42× 10 -4 ± 9.6 5× 10 -4 )mm2 ·s-1。扩散比值与时间呈明显相关 (r =0 .95 ,P <0 .0 0 1)。ADCv 在超早期增加后逐渐下降。结论 :超急性期脑缺血区水分子扩散速率下降 ,随时间延长扩散值逐渐上升。扩散的各向异性在超早期增加 ,随病程逐渐下降。DWI可在超急性期 (2h)发现缺血灶的存在 ,较CT及常规T1、T2 WI在脑梗死超早期诊断及演变中更有价值。超早期缺血区水分子扩散变化机制可能是超早期细? 展开更多
关键词 脑缺血 核磁共振 水代谢 诊断 各向异性 分子扩散法
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Preparation and in vitro Studies of Stealth PEGylated PLGA Nanoparticles as Carriers for Arsenic Trioxide 被引量:8
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作者 王志清 刘卫 +1 位作者 徐辉碧 杨祥良 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2007年第6期795-801,共7页
The aim of this study was to prepare arsenic trioxide (ATO)-loaded stealth PEGylated PLGA nanoparticles (PEG-PLGA-NPs) and to assess the merits of PEG-PLGA-NPs as drug carriers for ATO delivery. PEG-PLGA copolymer... The aim of this study was to prepare arsenic trioxide (ATO)-loaded stealth PEGylated PLGA nanoparticles (PEG-PLGA-NPs) and to assess the merits of PEG-PLGA-NPs as drug carriers for ATO delivery. PEG-PLGA copolymer was synthesized with methoxypolyethyleneglycol (Mw=5000), D, L-lactide, and glycolide by the ring-opening polymerization method. Amorphous ATO was transformed into cubic crystal form to increase its solu-bility in the organic solvent. ATO-loaded PEG-PLGA-NPs were prepared by the modified spontaneous emulsification solvent diffusion (SESD) method, and the main experimental factors influencing the characteristics of nanopar- ticles were investigated, to optimize the preparation. To confirm the escape of PEG-PLGA-NPs from phagocytosis by phagocytes, PEG-PLGA-NPs labeled rhodamine B uptake by murine peritoneal macrophages (MPM) were analyzed by flow cytometry. The results showed that the physicochemical characteristics of PEG-PLGA-NPs were affected by the type and concentration of the emulsifiers, polymer concentration, and drug concentration. ATO-loaded PEG-PLGA-NPs, with particle size of 120.8nm, zeta potential of-10.73mV, encapsulation efficiency of 73.6%, and drug loading of 1.36%, were prepared under optimal conditions. The images of transmission electron micros-copy (TEM) indicated that the optimized nanoparticles were near spherical and without aggregation or adhesion. The release experiments in vitro showed the ATO release from PEG-PLGA-NPs exhibited consequently sustained release for more than 26d, which was in accordance with Higuchi equation. The uptake of PEG-PLGA-NPs by MPM was found to decrease markedly compared to PLGA-NPs. The experimental results showed that PEG-PLGA-NPs were potential nano drug delivery carriers for ATO. 展开更多
关键词 arsenic trioxide PEGylated-PLGA nanoparticles ring-opening polymerization spontaneous emulsification solvent diffusion method in vitro drug release phagocytic uptake
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