A three‐dimensional supramolecular vanadium hydroxylamide complex: poly[di‐μ2‐aqua‐bis(hydroxylamido)‐μ3‐malonato‐oxidosodiumvanadium(V)]

The crystal structure of the title compound, [NaV(C₃H₂O₄)(NH₂O)₂O(H₂O)₂], is built up of NaO₆ and VO₅N₂ polyhedra connected through malonate bridges. The NaO₆ octahedra are linked by edge sharing in the equatorial plane to form one‐dimensional infinite chains. These chains are linked together by the malonate bridges to form two‐dimensional layers. The distorted VO₅N₂ pentagonal bipyramid is grafted on to the layer by a malonate carboxylate O atom. Adjacent layers are connected through O—H...O and N—H...O hydrogen bonds to build up a three‐dimensional supramolecular structure.     

A New Main Group Metal Coordination Polymer: Synthesis,Structure, and Dielectric Constant Property of [Na(C6H4N5)(H2O)2]n

The reaction of NaOH with 4‐(2H‐tetrazol‐5‐yl)pyridine affords the first tetrazole‐pyridine sodium coordination polymer with chain structure, [Na(C₆H₄N₅)(H₂O)₂]_n ( 1 ). The compound could be characterized by single‐crystal X‐ray diffraction analysis. The temperature dependence of dielectric permittivity remains unchanged almost within the measured temperature range of 80 K to 270 K at 1 <SC>MH</SC>z, and the frequency dependence of the permittivity showed rapidly drops from 31.5 to 4.3 within the measured frequency range of 200 to 1 MHz at room temperature.     

Synthesis of P1 aspartate-based peptide acyloxymethyl and fluoromethyl ketones as inhibitors of interleukin-1β-converting enzyme

Improved procedures have been developed for the synthesis of P1 aspartate-based 2,6-dichlorobenzoyloxymethyl ketone 1 and fluoromethyl ketone 2, the prodrugs of two potent ICE-inhibitors. 1 was prepared from (R)-trans-4,5-O-isopropylidene-4,5-dihydroxy-2-pentenecarboxylic acid ethyl ester; 2 was obtained via a nitro-aldol condensation as key step from in situ generated fluoroacetaldehyde.     

含硫希夫碱的研究(Ⅱ)——S-苯甲基-β-N-(2-羟基萘甲叉)-二硫代肼基甲酸酯与铜(Ⅱ)镍(Ⅱ)的配合物

使>C=O与NH_2NH-在一定条件下缩合,合成S-苯甲基-β-N-（2-羟基萘甲叉）-二硫代肼基甲酸酯,得到的产品用红外、元素分析、质谱确定,并以其为配体合成了铜（Ⅱ）镍（Ⅱ）的配合物,测定了它们的化学组成、电导、紫外或可见光谱,以及红外光谱,初步提出了配合物的结构,并测定了它们的形成常数。     

Lindleyanin and Bergapten‐8‐yl Sulfate from Pleurospermum lindleyanum

A novel cyclobutane‐type lignan with a six‐membered lactone ring, named lindleyanin ( 1 ), and a novel furocoumarinyl sulfate, named bergapten‐8‐yl sulfate ( 2 ), along with 7 known compounds were isolated from the whole plants of Pleurospermum lindleyanum. Their structures were established on the basis of spectral techniques and X‐ray crystallographic analysis of 2 .     

偶极天线用于高功率微波功率测量的研究

为了减小高功率微波尤其在低频段功率测量采用的接收天线的增益,本文设计了一种低增益的L波段偶极天线.通过理论分析和数值模拟,得到该天线的优化结果为:中心频率为1.75GHz,相应的增益为-5.55dB;在1.70GHz-1180GHz频带内,增益变化不超过1.1dB,功率容量的估算值为0.1MW,可以满足相应测量要求.     

底框砖房结构设计中的若干问题剖析

通过对底框砖房规范的探讨及对底框砖房实际工作经验的总结,对底框砖房结构设计中的若干问题进行了剖析,可供从事结构设计及相关研究人员参考.     

中、高能电子被SO2分子散射的微分截面、动量转移截面及弹性积分截面

在考虑分子内成键原子间的电子云重叠效应的基础上, 提出了一种能够准确计算“中、高能电子-分子”散射的微分截面、动量转移截面及弹性积分截面的修正势方法. 利用可加性规则、使用Hartree-Fock波函数并采用被这一方法修正过的复光学势, 在100—1000eV内对电子被SO₂分子散射的微分截面、动量转移截面及弹性积分截面进行了计算, 并将计算结果与实验及其他理论结果进行比较. 结果表明, 利用这一修正过的复光学势及可加性规则获得的微分截面比利用未修正的复光学势及可加性规则得到的结果准 关键词： 可加性规则 微分截面 动量转移截面 电子散射     

变形蔡氏电路中的混沌控制及Pspice仿真研究

针对变形蔡氏系统设计了电路,并通过Pspice仿真软件对其进行电路仿真.利用正比于系统变量的周期脉冲扰动法对其混沌进行控制,得到较好的控制结果.实验结果表明,所设计的控制器只需调整脉冲控制源的周期、脉宽和幅值,即可实现对混沌运动的控制.     

The investigation of coherent structures in the wall region of a supersonic turbulent boundary layer based on DNS database

Through temporal mode direct numerical simulation, flow field database of a fully developed turbulent boundary layer on a flat plate with Mach number 4.5 and Reynolds number Reθ =1094 has been obtained. Commonly used detection meth- ods in experiments are applied to detecting coherent structures in the flow field, and it is found that coherent structures do exist in the wall region of a supersonic turbulent boundary layer. The detected results show that a low-speed streak is de- tected by using the Mu-level method, the rising parts of this streak are detected by using the second quadrant method, and the crossing regions from a low-speed streak to the high-speed one are detected by using the VITA method respectively. Notwithstanding that different regions are detected by different methods, they are all accompanied by quasi-stream-wise vortex structures.