GRAIN SIZE DEPENDENT MAGNETISM IN GRANULAR MANGANESE PEROVSKITE La0.82Sr0.18MnO3

La_0.82Sr_0.18MnO₃ have been investigated. With grain growth, both an evident decrease of magnetization and the lattice distortions have been simultaneously observed. The phenomenon suggests a structure-coupled change of magnetism in the hole-doped manganese perovskite.     

Observation of topological rainbow in non-Hermitian systems

Topological photonic states have promising applications in slow light, photon sorting, and optical buffering. However, realizing such states in non-Hermitian systems has been challenging due to their complexity and elusive properties. In this work, we have experimentally realized a topological rainbow in non-Hermitian photonic crystals by controlling loss in the microwave frequency range for what we believe is the first time. We reveal that the lossy photonic crystal provides a reliable platform...     

椭圆型方程的并行迭代区域分裂法——多子区域情形

本文提出了一个有内交叉点的多子域区域分裂法。无交叉点的多子域分裂可归为两子域情形。在每一交叉点处取一子域覆盖之。称其为覆盖子域。不同交叉点的覆盖子域互不相交。本文的算法是把求解子区域上的Dirichlet问题,混合问题和覆盖子域上的Dirichlet问题相结合而得到的。利用了两子域Schwarz交替法和两子域并行迭代分裂法的思想。本算法具有高度并行性和通信局部性,适应于任意多个子区域的分裂。     

三元共聚反应序列分布的Monte Carlo模拟

本文利用Monte Carlo模拟获得了不同分子链长度的三元共聚反应产物[聚(苯乙烯-醋酸乙烯酯-马来酸酐)]的序列分布,我们发现三聚物的序列分布可以通过在反应过程中滴加活泼反应单体(本文中的苯乙烯)来加以控制。     

乙二胺四乙酸二钠/碳糊修饰电极测定银离子

报道EDTA/碳糊修饰电极的制备及对银离子的测定。该电极在硝酸介质中 - 0 .6 0V(vs .Ag/AgCl)电位下富集Ag+ ,在 +0 .0 8V处得到一个灵敏的阳极溶出峰 ,峰电流与Ag+ 浓度在 1.0× 10 -9～ 1.0× 10 -6mol/L范围呈良好线性关系 ,检出限为 6 .8× 10 -10 mol/L。     

一种铜催化合成异吲哚啉-1-酮的方法

本文设计了一种以邻苯甲腈和苯乙炔为原料,在铜催化剂的作用下环化生成异吲哚啉-1-酮的反应方法.以邻溴苯腈和苯乙炔作为反应模板,对溶剂、碱添加剂、催化剂、反应时间和温度做了探索,确定最佳反应条件为:碘化亚铜(0.02 mmol),去氧水(0.6 mmol),叔丁醇钾(0.3 mmol),1,4-二氧六环(0.2 mol·L^-1),100℃反应6 h.在最优反应条件下,对不同的反应底物进行了一系列的研究,底物适用性良好.     

磁场作用对明胶中卤化银乳剂制备的影响及机理探讨

本文报道了磁处理对明胶中单注法制备卤化银乳剂的影响,SEM照片及粒径分布曲线表明,在本实验磁场条件下,经磁化处理的乳剂较未经处理的乳剂,平均粒径大,颗粒分布均匀,晶粒分散状态良好.机理分析认为磁场处理影响了溶液中离子的水合程度,而且能增加溶液的有序程度,这两方面的因素导致了磁处理和未经磁处理之间的差异.磁处理能够影响明胶中卤化银的结晶过程,这可能为控制制备胶体中颗粒的大小及分布提供新思路.     

Determining the input dimension of a neural network for nonlinear time series prediction

Determining the input dimension of a feed-forward neural network for nonlinear time series prediction plays an important role in the modelling.The paper first summarizes the current methods for determining the input dimension of the neural network.Then inspired by the fact that the correlation dimension of a nonlinear dynamic system is the most important feature of it ,the paper pressents a new idea that the input dimension of the neural network for nonlinear time series prediction can be taken as an integer just greater than or equal to the correlation dimension.Fimally,some validation examples and results are given.     

HIERARCHICAL BASIS METHOD FOR COVOLUME METHOD FOR NONSYMMETRIC AND INDEFINITE ELLIPTIC PROBLEM

In this paper, hierarchical basis method for second order nonsymmetric and indefinite elliptic problem on a polygonal domain (possibly nonconvex) discreted by a vertex-centered covolume method is constructed.     

3-氧代-3-[3-三氟甲基-5,6-二氢[1,2,4]三唑并[4,3-α]吡嗪-7(8H)-基]-1-苯基丙烷-1-胺的合成

三唑类衍生物是重要的化工和药物合成中间体,而稠合三唑类衍生物因其独特的生理活性更是得到了广泛关注[1-2],其中3-三氟甲基-5,6,7,8-四氢[1,2,4]三唑并[4,3-α]哌嗪与β-氨基酸缩合得到的化合物是一类重要的二肽基肽酶-Ⅳ抑制剂 [3-4],可作为2型糖尿病的治疗药物,如2006年经美国FDA批准在美国上市的西他列汀(sitagliptin),此外二肽基肽酶-Ⅳ抑制剂还可用于肥胖症和高血压等疾病的预防和治疗[5].