A New Bibenzyl Glycoside from Dendrobium moniliforme

A new bibenzyl glycoside has been isolated from the stems of Dendrobium moniliforme (L.) Sw.(Orchidaceas).Its structure has been identified on the basis of spectroscopic and chemical methods.     

Independence and graph homomorphisms graph homomorphisms

A graph with n vertices that contains no triangle and no 5-cycle and minimum degree exceeding n/4 contains an independent set with at least (3n)/7 vertices. This is best possible. The proof proceeds by producing a homomorphism to the 7-cycle and invoking the No Homomorphism Lemma. For k ≥ 4, a graph with n vertices, odd girth 2k+1, and minimum degree exceeding n/(k+1) contains an independent set with at least kn/(2k+1) vertices; however, we suspect this is not best possible. © 1993 John Wiley & Sons, Inc.     

THE SCHWARZIAN DERIVATIVE IN SEVERAL COMPLEX VARIABLES(II)

ＴＨＥＳＣＨＷＡＲＺＩＡＮＤＥＲＩＶＡＴＩＶＥＩＮＳＥＶＥＲＡＬＣＯＭＰＬＥＸＶＡＲＩＡＢＬＥＳ（ＩＩ）ＧＯＮＧＳＨＥＮＧＹＵＱＩＨＵＡＮＧＺＨＥＮＧＸＵＥＡＮＭａｎｕｓｃｒｉｐｔｒｅｃｅｉｖｅｄＡｕｇｕｓｔ３０，１９９６．Ｄｅ...     

Dimensional Properties of Fractional Brownian Motion

Let B^α = {B^α（t）,t E R^N} be an （N,d）-fractional Brownian motion with Hurst index α∈ （0, 1）. By applying the strong local nondeterminism of B^α, we prove certain forms of uniform Hausdorff dimension results for the images of B^α when N 〉 αd. Our results extend those of Kaufman for one-dimensional Brownian motion.     

叠层连续开口圆柱壳的精确解

抛弃任何有关位移和应力模式的假设，引入δ-函数，对正变异性连续开口圆柱壳建立状态方程．给出薄的、中厚的和强厚的叠层连续开口圆柱壳静力问题的统一的精确解．数值结果和SAPS解进行了对比．     

Isolation and Structure Elucidation of Nortriterpenoids from Schisandra rubriflora

Seven new highly oxygenated nortriterpenoids, rubriflorins D–J ( 1 – 7 ), were isolated from the leaves and stems of Schisandra rubriflora, and their structures were elucidated on the basis of extensive analysis of spectroscopic data. These new compounds feature the opening of ring A compared with related known nortriterpenoids isolated from the genus Schisandra and showed weak activity against HIV‐1.     

Palladium-catalyzed C-N bond formation: synthesis of 1-aryl-1H-pyrazoles from β-bromovinyl aldehydes and arylhydrazines

Cyclic and acyclic β-bromovinyl aldehydes are cyclized with an array of arylhydrazines in toluene at 125 °C in the presence of a palladium catalyst and a phosphorus chelating ligand together with NaO^tBu to give 1-aryl-1H-pyrazoles in moderate to good yields.     

HPLC法测定阿奇霉素葡萄糖注射液中阿奇霉素的含量

利用高效液相色谱法，以VP-ODS型色谱柱，乙腈-异丙醇-水-氨水（60：25：15：0.1)为流动相，于210nm波长处测定了阿奇霉素葡萄糖注射液中阿奇霉素葡萄糖注射液中阿奇霉素的含量。阿奇霉素的浓度在0.75-1.75mg/mL线性关系良好，线性方程的A=881910.4c-16208.2，相关系数r=0.9999。阿奇霉素的平均回收率为99.59%，测定结果的相对标准偏差为1.31%。     

Ethylene–propylene copolymerization with bis(β‐enaminoketonato) titanium complexes activated with modified methylaluminoxane

Ethylene–propylene copolymerization, using [(Ph)NC(R₂)CHC(R₁)O]₂TiCl₂ (R₁ = CF₃, Ph, or t‐Bu; R₂ = CH₃ or CF₃) titanium complexes activated with modified methylaluminoxane as a cocatalyst, was investigated. High‐molecular‐weight ethylene–propylene copolymers with relatively narrow molecular weight distributions and a broad range of chemical compositions were obtained. Substituents R₁ and R₂ influenced the copolymerization behavior, including the copolymerization activity, methylene sequence distribution, molecular weight, and polydispersity. With small steric hindrance at R₁ and R₂, one complex (R₁ = CF₃; R₂ = CH₃) displayed high catalytic activity and produced copolymers with high propylene incorporation but low molecular weight. The microstructures of the copolymers were analyzed with ¹³C NMR to determine the methylene sequence distribution and number‐average sequence lengths of uninterrupted methylene carbons. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5846–5854, 2006