Sturm-Liouville边值问题解的存在性与上下解方法

通过建立一个新的极大值原理,讨论Sturm-Liouville边值问题{-(p(t)u′(t))′+q(t)u(t)=f(t,u),t∈I,R1(u)=α0u(0)-β0p(0)u′(0)=0,R2(u)=α1u(1)+β1p(1)u′(1)=0解的存在性.其中f:I×R→R为Caratheodory函数。在不限制f关于u的增长阶,不假定f关于u的单调性的一般情形下,用上     

Banach空间中脉冲微分方程初值问题解的存在性

利用凝聚映射的不动点定理,对脉冲函数不加紧性条件和其他额外条件,通过逐段延拓的方法,获得了无穷区间上脉冲微分方程初值问题解的存在性,本质上改进了某些已知的结果.     

淀粉黄原胶交联膜的制备及载药性能测定

以马铃薯淀粉和黄原胶为单体制备得到了淀粉黄原胶交联膜,运用红外光谱、扫描电子显微镜、热重分析手段对产物进行了表征;以亚甲基蓝为模型药物,研究了交联膜在两种不同介质中时间、温度、药液浓度对其载药性能的影响;实验结果表明:淀粉与黄原胶都与交联剂发生了反应形成了交联膜,膜表面光滑,有较高耐热性,在pH=7.4的PBS中的载药性能优于在0.9%的生理盐水中的载药性能,且在这两种介质中载药趋势相同,都在30min,35℃时的条件下有较好的载药性。     

PEG-400中一锅法合成4H-吡喃衍生物

PEG-400作反应介质,90℃下通过芳醛、1,3-二羰基化合物和丙二腈三组份缩合反应,一锅法合成了11种6-氨基-5-腈基-4-芳基-2-甲基-4H-吡喃类衍生物。产物结构经IR、1H NMR、13C NMR及Elemental Analysis得到确证。该方法具有产率高、操作简单、环境友好等优点。     

A modified QuEChERS-gas chromatography-mass spectrometry method for the determination of pesticide residues in Lonicera japonicae FlosEI北大核心CSCD

A modified QuEChERS-gas chromatography-mass spectrometry method using multi-walled carbon nanotubes （MWCNTs）as adsorbent was established for the determination of 72 pesticide residues in Lonicera japonicae Flos. The sample was extracted with Association of Official Agricultural Chemists （AOAC）extracting package，purified with MWCNTs-modified purification tube，analyzed with dynamic multiple reaction monitoring mode，and quantified with external standard method of matrix-matched standard curve. The 72 pesticides showed good linearities in the corresponding concentration ranges with correlation coefficients greater than 0.9936. The limits of detection were 0.001-0.178 μµg/kg，and the limits of quantitation were 0.002-0.593 μµg/kg. The average recoveries for four spiked levels ranged from 60.1% to 118.0%，with the relative standard deviations of 2.2%-17%. © 2023, Youke Publishing Co.,Ltd. All rights reserved.