A divergent approach to apoptolidin and FD-891: asymmetric preparation of a common intermediate

Biologically active Apoptolidin and FD-891 have structural similarity in their macrocyclic cores. Asymmetric preparation of a common intermediate in the total synthesis of these two macrolides is presented. A modified Masuyama Sn-allylation was employed to control the relative stereochemistry in the synthesis of the intermediate.     

A Divergent Synthesis of 1,8-Naphthyridines and Hydropyridopyrimidinones by the Reactions of o-Aminonitriles with Ketones

An efficient divergent synthesis of substituted 1,8‐naphthyridine and hydropyridopyrimidinone derivatives was developed by the reactions of o‐aminocyanopyridines and ketones based on different catalytic conditions.     

在球面散心冲击波作用下JB-9014炸药冲击引爆过程实验研究

采用双灵敏度VISAR对JB-9014炸药在20 GPa的球面散心冲击波作用下冲击引爆过程开展了实验研究。测得的不同厚度JB-9014炸药/窗口界面的粒子速度历程表明,到爆轰距离为2~3 mm,在3~5mm处反应冲击波已发展为稳定爆轰波。开展了相应的初步数值计算工作,计算结果与实验基本吻合。     

Analogues of some Tauberian theorems for bounded variation

In this paper definitions for “bounded variation”, “subsequences”, “Pringsheim limit points”, and “stretchings” of a double sequence are presented. Using these definitions and the notion of regularity for four dimensional matrices, the following two questions will be answered. First, if there exists a four dimensional regular matrix A such that Ay = Σ _k,l=1,1 ^∞∞ a _m,n,k,l y _k,l is of bounded variation (BV) for every subsequence y of x, does it necessarily follow that x ∈ BV? Second, if there exists a four dimensional regular matrix A such that Ay ∈ BV for all stretchings y of x, does it necessarily follow that x ∈ BV? Also some natural implications and variations of the two Tauberian questions above will be presented.     

Divergent beam hard X‐ray diffraction used for the simultaneous imaging of radiographic and crystallographic information

A transmission method and experimental set‐up were developed for the nondestructive characterisation of the quality of bulk single crystals/ large coarsely crystalline polycrystals or components. The method works by combination of X‐ray projection microscopy (X‐ray shadow microscopy) with bremsstrahlung interferences from divergent beam hard X‐rays, in order to form simultaneously enlarged radiographic images and crystallographic information in one measurement. The method and equipment are patent registered. In the paper some of the first results are presented. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

非傍轴矢量光束二阶矩的发散特性

基于非傍轴矢量光束横截面上光强的精确表示和矢量二阶矩理论,应用严格的角谱表示的矢量衍射理论,对任意非傍轴矢量衍射光束的传输进行了系统的研究.给出了光束的束宽、横向发散角的积分表达式,论证了非傍轴矢量光束二阶矩的发散特性.对非傍轴矢量光束的束宽、发散角的定义及一些相关的问题进行了分析和讨论. 关键词： 矢量衍射理论 光束传输 矢量二阶矩 发散特性     

Time‐ and spatial‐resolved XAFS spectroscopy in a single shot: new analytical possibilities for in situ material characterization

A new concept that comprises both time‐ and lateral‐resolved X‐ray absorption fine‐structure information simultaneously in a single shot is presented. This uncomplicated set‐up was tested at the BAMline at BESSY‐II (Berlin, Germany). The primary broadband beam was generated by a double multilayer monochromator. The transmitted beam through the sample is diffracted by a convexly bent Si (111) crystal, producing a divergent beam. This, in turn, is collected by either an energy‐sensitive area detector, the so‐called color X‐ray camera, or by an area‐sensitive detector based on a CCD camera, in θ–2θ geometry. The first tests were performed with thin metal foils and some iron oxide mixtures. A time resolution of lower than 1 s together with a spatial resolution in one dimension of at least 50 µm is achieved.     

大学物理实验中发散思维的引导与训练

发散性思维是创新能力的基础。大学物理实验是理工类学生最早接触的实验,在分析现存物理实验教学模式存在问题的基础上,将发散性思维训练作为大学物理实验课堂的目标之一,提出了课堂发散性思维训练的三种方式。最后通过某个具体的物理实验,对实验教学中的发散思维训练内容及过程进行了说明。     

聚酰胺-胺型树枝状大分子1H和13C-NMR研究

采用发散合成法合成了0．5～3.0代的树枝状大分子聚酰胺-胺，测定了系列聚酰胺-胺的^1H—NMR和^13C—NMR谱，结果表明，合成产物的分子结构与理论结构相符，而^13C—NMR谱的测定结果表明了整代产品中含有少量的原料乙二胺，合理地解释了随着支化代的增加，收率超过100％这一实验现象．