高阶半线性抛物型方程组的生命跨度

其中m,P,q>1．利用试验函数方法,首先推导一些积分不等式,然后对方程组爆破解的生命跨度 [0,T)给出估计．     

基于分布参数模型的CO_2蒸发器结构参数研究

在设计工况下,建立了用于跨临界二氧化碳热泵热水器的套管式蒸发器的稳态分布参数模型,对其结构参数进行了敏感性分析,指出了它们的合理变化范围:管内套1根管时,内管外径应至少大于11.00mm,低于13.00mm,外管内径应在20.00mm以上,23.00mm以下;管内套多根管时,以管内套3根管的性能为最优。优化设计结果对开发二氧化碳蒸发器产品具有一定的指导意义。     

Asymptotically self‐similar global solutions for a higher‐order semilinear parabolic equation

In this paper, we study the higher‐order semilinear parabolic equation where m, p>1 and $a\,\in\,\mathbb{R}$. For p>1+2m/N, we prove that the global existence of mild solutions for small initial data with respect to some norm. Some of those solutions are proved to be asymptotic self‐similar. Copyright © 2009 John Wiley & Sons, Ltd.     

Trimetallic Au@PdPt core-shell nanoparticles with ultrathin PdPt skin as highly stable electrocatalysts for the oxygen reduction reaction in acid solution

To design efficient and low-cost core-shell electrocatalysts with an ultrathin platinum shell, the balance between platinum dosage and durability in acid solution is of great importance. In the present work, trimetallic Au@PdPt core-shell nanoparticles(NPs)with Pd/Pt molar ratios ranging from 0.31:1 to 4.20:1 were synthesized based on the Au catalytic reduction strategy and the subsequent metallic replacement reaction. When the Pd/Pt molar ratio is 1.19:1(designated as Au@Pd_(1.19) Pt_1 NPs), the superior electrochemical activity and stability were achieved for oxygen reduction reaction(ORR) in acid solution. Especially, the specific and mass activities of Au@Pd_(1.19) Pt_1 NPs are 1.31 and 6.09 times higher than those of commercial Pt/C catalyst. In addition, the Au@Pd_(1.19) Pt_1 NPs presented a good durability in acid solution. After 3000 potential cycles between 0.1 and 0.7 V(vs. Ag/AgCl), the oxygen reduction activity is almost unchanged. This study provides a simple strategy to synthesize highperformance trimetallic ORR electrocatalyst for fuel cells.     

基于专业课程培养本科生创新精神和科研能力——以无机合成化学为例

以无机合成化学为例进行了基于专业课程培养本科生创新精神和科研能力的教学方法改革,探索以专业课程为载体加强本科生创新精神和科研能力的培养,提高学生在学习中的主体地位,培养勤于思考、敢于怀疑、勇于创新的素质和精神,提升科研能力,形成终身学习的能力和习惯。教学改革取得了一定的成效。     

香豆素合成工艺的改进

香豆素是一种用途广泛的香料,虽然已有多种合成方法,但国内仍采用以水杨醛为原料的路线(产率为60%左右),提高产率是改进其合成工艺的关键。我们曾以氟化钠代替乙酸钠作催化剂,以水杨醛和乙酐为原料合成了香豆素,提高了产率。本文又采用两     

Thermal Properties of Carboxymethylcellulose and Methyl Methacrylate Graft Copolymers

Carboxymethyl cellulose and methyl methacrylate graft copolymers (CMC-g-PMMA) were synthesized by using potassium persulphate (KPS) as initiator. These graft copolymers were characterized by Fourier transform infrared spectra (FTIR), thermogravimetric analyses (TGA), and differential scanning calorimeter analyses (DSC). In addition, the nonisothermal thermal decomposition kinetics of copolymers was studied. The experimental results indicated that in the temperature range from 300°C to 450°C, the copolymer had a mass loss. The activation energy was 41.96 kJ/mol, and the logarithm of the Arrhenius coefficient (lnA) was 17.31.