Quadratic perturbations of a class of quadratic reversible center of genus one

This paper is concerned with the quadratic perturbations of a one-parameter family of quadratic reversible system, having a center of genus one. The exact upper bound of the number of limit cycles emerging from the period annulus surrounding the center of the unperturbed system is given.     

不同粒度SiC颗粒低温制备SiC泡沫陶瓷的性能

以SiC陶瓷前驱体聚碳硅烷(polycarbosilane,PCS)为粘结剂、SiC微粉为填料、聚氨酯海绵为模板,低温制备出了SiC泡沫陶瓷。研究了SiC颗粒粒度和PCS含量对SiC泡沫陶瓷线收缩率、体积密度、微观结构与抗弯强度的影响。确定了不同粒度SiC颗粒制备泡沫陶瓷的最佳烧成温度。结果表明,随SiC颗粒粒度与PCS含量的增加泡沫陶瓷的线收缩率增大、体积密度降低;泡沫陶瓷的抗弯强度随SiC颗粒粒度的增大而降低;颗粒粒度小于1μm时,最佳烧成温度为1200℃,颗粒粒度大于1μm时,最佳烧成温度为1100℃;PCS在1100℃与1200℃热解可得到β-SiC晶粒,其晶粒尺寸为12.2 nm与19.6 nm。     

Mittag-Leffler-Ulam stabilities of fractional evolution equations

In this paper, we present and discuss four types of Mittag-Leffler-Ulam stability: Mittag-Leffler-Ulam-Hyers stability, generalized Mittag-Leffler-Ulam-Hyers stability, Mittag-Leffler-Ulam-Hyers-Rassias stability and generalized Mittag-Leffler-Ulam-Hyers-Rassias stability for a fractional evolution equation in Banach spaces.     

Ripening of single-layer InGaAs islands on GaAs（001）

The present paper discusses our investigation of InGaAs surface morphology annealed for different lengths of time.After annealing for 15 min,the ripening of InGaAs islands is completed.The real space scanning tunneling microscopy(STM) images show the evolution of InGaAs surface morphology.A half-terrace diffusion theoretical model based on thermodynamic theory is proposed to estimate the annealing time for obtaining flat morphology.The annealing time calculated by the proposed theory is in agreement with the experimental results.     

含1,2,4-三唑-5-硫酮席夫碱的新型1,2,4-三唑并[1,5-a]嘧啶衍生物的合成及生物活性研究

以2-苄硫基-5-甲基-7-羟基-1,2,4-三唑并[1,5-a]嘧啶为原料,经醚化、肼解、成盐、关环和席夫碱反应合成了20个新型的含1,2,4-三唑-5-硫酮席夫碱的1,2,4-三唑并[1,5-a]嘧啶类化合物,通过IR,1H NMR,MS和元素分析对所合成的化合物进行了结构表征.初步生物活性测试结果表明,部分化合物表现出一定的抑菌或较好的抗烟草花叶病毒(TMV)活性.在500μg/mL浓度下,化合物6b,6f和6p对TMV的抑制率分别为41%,43%和40%.     

1,2,3,4-四氢喹啉衍生物合成进展

1,2,3,4-四氢喹啉类化合物是一类重要的含氮杂环化合物,具有众多的生物活性和广泛的用途,因此,四氢喹啉合成新方法的研究受到人们的关注。本文分别从通过氢化还原策略、关环转化反应策略以及通过多分子缩合反应策略等几个方面综述1,2,3,4-四氢喹啉衍生物合成的进展。     

电活化玻碳电极差分脉冲溶出伏安法测定磺胺嘧啶

采用线性循环溶出伏安法和差分脉冲溶出伏安法对磺胺嘧啶在电活化玻碳电极上的电化学行为进行了研究。玻碳电极在PBS溶液中(pH 7.0),用恒电位法在1.7 V阳极氧化400 s,在B-R缓冲溶液中,磺胺嘧啶在1.02V(vs.Ag/AgCl)处有一良好的氧化峰,在0.02～0.25 V/s范围内,其氧化峰电流与扫描速率呈良好线性关系,表明电极过程为受吸附控制的不可逆过程。差分脉冲溶出伏安法的氧化峰电流(Ipa)与磺胺嘧啶浓度1×10-6～1×10-4mol/L范围内呈良好的线性关系(r=0.9977),检出限为8.7×10-7mol/L(S/N=3)。方法已用于分析磺胺嘧啶片剂的分析。     

Boundary value problems for fractional differential equations involving Caputo derivative in Banach spaces

In this paper, we study boundary value problems for fractional differential equations involving Caputo derivative in Banach spaces. A generalized singular type Gronwall inequality is given to obtain an important priori bounds. Some sufficient conditions for the existence of solutions are established by virtue of fractional calculus and fixed point method under some mild conditions. Two examples are given to illustrate the results.     

光谱法研究1,3-硫杂杯[4]罗丹明乙二胺酰胺衍生物对Fe3+的探针性能

利用硫杂杯[4]芳烃衍生物与罗丹明乙二胺发生酰化反应,合成了2个具有双罗丹明基团的1,3-硫杂杯[4]罗丹明乙二胺酰胺衍生物.在实验条件下,衍生物与Fe3+均能形成1:1配合物,配合物的形成诱导了衍生物分子中罗丹明基螺环开环,而表现出良好的荧光和比色探针性能.1,3-硫杂杯[4]罗丹明酰胺-2,4-酯对Fe3+的选择性高于1,3-硫杂杯[4]罗丹明酰胺-2,4-酸.光谱法考察了探针对Fe3+响应的分析特征,测定了合成样品.     

新型罗丹明B席夫碱荧光探针的光谱性质研究

合成了一种席夫碱结构的罗丹明B衍生物.研究表明,该衍生物能与Fe3+形成稳定配合物,同时伴随显著的荧光增敏和吸收增强.衍生物不仅对Fe3+呈现良好的荧光及比色探针性能,其与金属离子形成的配合物也是一种研究牛血清白蛋白的高灵敏荧光探钊.