Effect of metal ions in organic synthesis. Part XXXI. Synthesis of new 3-carbonyl- and 3-carboxy-1-heterocyclaminopyrroles by copper(II) chloride-catalyzed reaction of heterocyclic azoalkenes

The direct synthesis of a new class of unknown 1-heterocyclamino-3-carbonylpyrroles and 1-heterocyclamino-3-carboxypyrroles by copper(II) chloride-catalyzed reaction of heterocyclic conjugated azoalkene derivatives with β-diketones and β-ketoesters is reported.     

多亚甲基桥连双巴比妥的合成及鉴定

在ＰＴＣ条件下合成了多亚甲基桥连的双巴比妥类化合物１～３，并通过了元素分析，ＩＲ及＾１ＨＮＭＲ予以鉴定。     

Preparation of gradient copolymers via ATRP using a simultaneous reverse and normal initiation process. I. Spontaneous gradient

Spontaneous gradient copolymers were prepared in both bulk and miniemulsion systems via Atom Transfer Radical Polymerization (ATRP) utilizing a Simultaneous Reverse and Normal Initiation (SR & NI) process. Both instantaneous and cumulative compositions were used to characterize the gradient copolymers. The gradient copolymers were obtained with an array of gradient compositions ranging from a subtle to strong variation in monomer distribution along the polymer backbones, depending on the ratio of comonomers initially added to the copolymerization system. The compositions of the gradient copolymer produced in miniemulsion systems were similar to those generated in bulk. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3616–3622, 2005     

用特征多项式构造相移干涉相位提取算式

用相移干涉术测量物体表面形貌时，各种误差因素特别是相移器移相误差的影响使得表面形貌的测量偏离了实际值，甚至会产生形貌失真的现象。采用傅里叶分析的方法对相位提取算式作了理论分析，并根据特征多项式设计分析理论构造了新的、对移相误差不敏感的相位提取算式。经实验验证，该算法有效地提高了相移干涉仪测量表面形貌的Ra值，重复测量精度达5倍以上，使测量结果更接近实际值。     

Silica-supported l-proline organocatalysts for asymmetric aldolisation

New heterogenised silica-based organocatalysts have been prepared via the sol–gel process from two silylated derivatives of l-proline, featuring either a carbamate or an ether linker. Co-gelification with variable amounts of TEOS was performed with and without porogen to yield high surface area solids. These materials were evaluated as heterogeneous phase organocatalysts for the asymmetric aldol reaction of p-nitrobenzaldehyde with acetone.     

有机磷化合物的NMR研究Ⅵ.1,3,2-氧氮磷杂环戊烷的13C谱

测定了19个2-硫代-2-(二乙基氨基)-3-取代苯甲(磺)酰基-1,3,2-氧氮磷杂环戊烷的¹³C NMR参数.在苯甲酰类化合物中,邻位有非氢取代基时,非环的²J(PNC)随温度而变化(0~6.1Hz),这是因羧基与苯环空间位置(构象)随温度变化所致.     

人工神经网络应用于维生素B族4组分同时测定

应用人工神经网络原理，采用Levenberg-Marquardt BP算法，对于吸收光谱严重重叠的维生素B1，B2，B6和烟酰胺4组分同时进行含量测定。四者的平均回收率分别为100％，98％，96％，100％。该方法用于复合维生素B片剂中B1，B2，B6和烟酰胺的同时测定，获得较满意的结果。实验表明，该方法与现有的算法相比具有训练速度快、预测结果准确度高等特点，有望能成为多组分分析的有效方法之一。     

Efficient and Eco-friendly Process for the Synthesis of Bi（indolyl）-methanes Catalyzed by Sodium Hydrogensulfate Monohydrate in Ionic Liquid n-Butylpyridinium Tetrafluoroborate

Indole fragment is featured widely in a wide variety of pharmacologically and biologically active compounds1. A large number of bi(indolyl)methanes have been reported to be isolated from terrestrial and marine natural sources, viz. parasitic bacteria, tun…     

Lamellar morphology and equilibrium melting temperature of syndiotactic polystyrene in β‐crystalline form

Lamellar morphology and thickness of syndiotactic polystyrene (sPS) samples melt‐crystallized at various temperatures were probed using transmission electron microscopy (TEM) and small‐angle X‐ray scattering (SAXS). In addition, the melting temperature and enthalpy of the crystallized samples were characterized with differential scanning calorimetry. Under appropriate thermal treatments, all the samples investigated in this study were crystallized into β′ crystal modification, as revealed by wide‐angle X‐ray diffraction. From the SAXS intensity profiles, a scattering peak (or shoulder) associated with lamellar features as well as the presence of anomalous scattering at the zero‐scattering vector were evidently observed. The peculiar zero‐angle scattering was successfully described by the Debye–Bueche model, and subtraction of its contribution from the raw intensity profiles was carried out to deduce the intensity profile merely associated with the lamellar feature. The lamellar thickness obtained from Lorentz‐corrected intensity profiles in this manner agrees with that measured from the TEM images, provided that the two‐phase model is applied. On the basis of the Gibbs–Thomson equation, the modest estimations of equilibrium melting temperature and the surface free energy of the fold lamellar surface are 292.7 ± 2.7 °C and 20.2 ± 2.6 erg/cm², respectively, when lamellar thicknesses measured by TEM are applied. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1626–1636, 2002     

Decomposition of search for -structures in DAGs

We show that the problem of searching for v-structures in a directed acyclic graph can be decomposed into searches in its decomposed subgraphs. This result simplifies the search for v-structures and the recovery of local causal relationships.