Periodic nonautonomous differential equations with noninstantaneous impulsive effects

In this paper, we study a new class of periodic nonautonomous differential equations with periodic noninstantaneous impulsive effects. A concept of noninstantaneous impulsive Cauchy matrix is introduced, and some basic properties are considered. We give the representation of solutions to the homogeneous problem and nonhomogeneous problem by using noninstantaneous impulsive Cauchy matrix, and the variation of constants method, adjoint systems, and periodicity of solutions is verified under standard periodicity conditions. Further, we show the existence and uniqueness of solutions of semilinear problem and establish existence result for periodic solutions via Brouwer fixed point theorem and uniqueness and global asymptotic stability via Banach fixed point theorem.     

Joint Reducing Subspaces of Multiplication Operators and Weight of Multi-variable Bergman Spaces

This paper mainly concerns a tuple of multiplication operators defined on the weighted and unweighted multi-variable Bergman spaces, their joint reducing subspaces and the von Neumann algebra generated by the orthogonal projections onto these subspaces. It is found that the weights play an important role in the structures of lattices of joint reducing subspaces and of associated von Neumann algebras. Also, a class of special weights is taken into account. Under a mild condition it is proved that if those multiplication operators are defined by the same symbols, then the corresponding von Neumann algebras are $*$-isomorphic to the one defined on the unweighted Bergman space.     

非完全消化-火焰原子吸收光谱法测定水果中铜铁锌

用非完全消化法处理杏、油桃和草莓样品,即在低温下用浓硝酸-高氯酸(3+1)混合酸消解样品,再加入乳化剂TX-10溶解消化过程中所产生的油脂,将所得橙红色的均匀透明溶液用火焰原子吸收光谱法测定其中铜、铁和锌元素的含量.对样品处理条件、混合酸中杂质及共存TX-10的干扰进行了试验.铜、铁和锌的检出限(3s/k)分别为0.019,0.145,0.009 mg·L-1.用此法测定水果实样中铜、铁和锌的含量,所得结果与灰化法测定结果相一致.     

Design,synthesis and biological activity of some novel benzimidazole derivatives against Coxsackie virus B_3

A series of novel benzimidazole derivatives was synthesized and their anti-Coxsackie virus B_3(CVB_3) activity was evaluated in VERO cells.Compounds 9 and 10 exhibited better inhibitory activity than those of ribavirin(RBV) with IC_(50) values of 5.30 and 1.06μg/mL,respectively.     

Gorenstein正则环、奇点范畴和Ding模

本文证明了任意环的整体Ding投射维数和整体Ding内射维数一致,研究了奇点范畴和相对于Ding模的稳定范畴间的关系,并刻画了Gorenstein (正则)环以及环的整体维数的有限性.     

Effect of SDBS on interfacial electron transfer at the liquid/liquid interface by thin layer method

The effect of an adsorbed anionic surfactant sodium dodecyl benzene sulfonate(SDBS) on electron transfer(ET) reaction between ferricyanide aqueous solution and decamethylferrocene(DMFc) located on the adjacent organic phase was investigated for the first time by thin layer method.The adsorption of SDBS at the interface resulted in a decay in the cathodic plateau current of bimolecular reaction with increasing concentrations of SDBS in aqueous phase.However,the rate constant of electron transfer(k_(et)) i...     

Synthesis of new 2-aryl-6-styryl-2,3-dihydropyridin-4(1H)-one derivatives from curcuminoids

Series of new 2-aryl-6-styryl-2,3-dihydropyridin-4(1H)-one derivatives were synthesized in acceptable to good yields by treatment of the curcuminoids with aqueous ammonia,the mechanism was proposed.By modification of the primary products,total 13 new compounds were obtained.The structures of all products were elucidated by spectroscopy analysis including HR-MS,~1H NMR and ~(13)C NMR.     

CdTe量子点标记的DNA电化学传感器的研究

利用碳纳米管和CdTe量子点(QDs)组装的电化学传感器,建立了一种识别DNA的新方法.将氨基修饰的单链DNA探针共价键合固定在带有羧基的碳纳米管修饰的金电极上,然后与CdTe QDs标记的目标DNA进行杂交.利用差分脉冲法(DPV)和循环伏安法对目标DNA的固定和杂交进行表征,通过电活性指示剂柔红霉素(DNR)的DPV峰电流变化,对互补DNA、非互补DNA和单碱基错配DNA序列进行识别.与未标记CdTe QDs的目标DNA相比,标记CdTe QDs的目标DNA序列的电流响应灵敏度明显提高.DNA电化学传感器检测的优化条件:DNR的浓度为1.67×10-5 mol/L,DNA杂交时间为80 min,杂交温度为55 ℃.在1.0×10-13 ～1.0×10-8 mol/L范围,目标DNA浓度的对数值与其响应的DPV信号(还原峰电流)呈线性关系,检出限为3.52×10-14 mol/L(S/N=3,n=9),线性方程为ΔI=50.22+3.567 lgcDNA,相关系数为0.996 6.对1.0×10-10 mol/L的目标DNA样品进行重复测定,相对标准偏差为4.8%(n=5),重复性良好.     

(R)-2-甲基半胱氨酸盐酸盐的合成方法改进

以L-半胱氨酸甲酯盐酸盐为起始原料,经4步反应合成了(R)-2-甲基半胱氨酸盐酸盐.在关键中间体(2R, 4R)-2-叔丁基-3-甲酰基-4-甲基-1,3-噻唑烷-4-甲酸甲酯(4)的合成中,采用Self-regeneration of stereocenters原理,用六甲基二硅胺钠取代文献方法中的二异丙基胺基锂,4的收率由文献的56%提高至90%.化合物的结构经1H NMR和MS表征.     

电感耦合等离子体原子发射光谱法测定玻璃澄清剂中砷的前处理方法研究

研究了几种常规前处理方法对玻璃澄清剂中砷测定的影响,建立了一种预氧化处理、后酸式湿分解的前处理方法.较传统碱熔法而言,该方法简单方便且可操作性强,同时可避免传统酸溶分解过程中可能造成的砷挥发损失.对预氧化处理使用的氧化剂和预氧化过程进行了筛选与优化,确定了4种湿式预氧化-酸消化分解方法,并利用端视电感耦合等离子体发射光谱实现了砷的直接测定.通过精密度和准确度实验,得到4种方法的相对标准偏差均小于2%,样品的加标回收率为98% ～106%,表明该前处理方法准确度高、精密度好.将所建立的分析方法用于玻璃澄清剂样品的测定,结果令人满意.