口述史作为社区研究的方法

口述史在社会学中的意义,不仅在于可以通过口述记忆研究个人在大叙事中的生命沉浮,更在于它提供了深挖人的精神世界的社会性的方法。其主要研究对象,可称之为记忆社区的问题。记忆社区至少包括三个维度：地点、时间和人物。它以个人的口述为起点,基于人的生命实践,富含主体性和情感性特征,但其勾勒出的是一个囫囵的整体,有极强的社会性特征,蕴含丰富的社会和文化意义。口述记忆中的文化是一种经由个体化实践而感悟出的文化感,家庭中的“义务感”是它的一个典型形式,其表现为社会力的方式,成为黏合社区的重要机制。记忆社区本质上是人和物的混融,它呈现的社区形象是一个有机整体。口述史能够作为社区研究方法,不仅在于它呈现了独特的记忆社区,还在于指明了社会建设和基层社会治理的深层机制,这便是从人心的角度,揭示了人之安所遂生的社区力量。记忆社区概念提醒我们,历史上积淀下来的社区文化和社会底蕴是值得探究和善用的凝聚社区的相对稳固的机制。     

Mechanistic investigation of imine formation in ruthenium‐catalyzed N‐alkylation of amines with alcohols

Imines are observed frequently in ruthenium‐catalyzed N‐alkylation of amines with alcohols. Herein, nitrogen–phosphine functionalized carbene ligands were developed and used in ruthenium‐catalyzed N‐alkylation to explore the mechanism of imine formation. The results showed that strongly electron‐donating ligands were beneficial for imine formation and alcohol dehydrogenation to generate acid. In addition, with an increase of electron density of nitrogen atom in substituted amines, the yield of imines in N‐alkylation was improved. At the same time, with electron‐rich imines as substrates, the transfer hydrogenation of imines became difficult. It is suggested that strongly electron‐donating ligands and substrates caused an increase of electron density on the ruthenium center, which resulted in the elimination of hydrogen atoms in active species [LRuH₂] as hydrogen gas rather than transfer onto the imine coordinated with the ruthenium center.     

基于配体结构的Grb2-SH2抑制剂的结构优化:更高的活性、更少的电荷、更低的肽性

生长因子受体结合蛋白2(Grb2)在致癌基因Ras活化的信号传导通路中起着关键作用,目前被广泛认为是抗肿瘤药物设计的优秀靶标.对Grb2-SH2抑制剂的研究进展进行了综述,主要针对关键残基磷酸酪氨酸的高电荷性和多肽结构的低生物相容性两个缺陷,基于天然配体与Grb2-SH2相互作用的结构特征,围绕提高活性和简化结构开展的系统构效关系和合理结构优化研究,为进一步开发磷酸酪氨酸介导的Grb2-SH2抑制剂成为新型抗肿瘤药物提供结构和理论基础.     

When electron exchange is chemical exchange-assignment of 1H NMR spectra of paramagnetic cobalt(II)-2,2':6'2''-terpyridine complexes

Electron exchange between [Co(terpy)2]3+ and [Co(terpy)2]2+ can be monitored by 1H NMR exchange spectroscopy and allows the cobalt(II) spectra to be fully assigned.     

α‐Fe2O3 Polyhedral Nanoparticles Enclosed by Different Crystal Facets: Tunable Synthesis,Formation Mechanism Analysis,and Facets‐dependent n‐Butanol Sensing Properties

Three kinds of polyhedral α‐Fe₂O₃ nanoparticles enclosed by different facets including oblique parallel hexahedrons (op‐hexahedral NPs), cracked oblique parallel hexahedrons (cop‐hexahedral NPs), and octadecahedral nanoparticles (octadecahedral NPs), were successfully prepared by simply changing only one reaction parameter in the hydrothermal process. The structural and morphological of the products were systematically studied using various characterizations including X‐ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), revealing that the three kinds of α‐Fe₂O₃ nanoparticles were enclosed by {104}, {110}/{104}, and {102}/{012}/{104} crystal planes, respectively. The exposed facets and shape of the nanocrystals were found to be affected by the adding amount of ethylene glycol in the solvent. The gas‐sensing properties and mechanism of the α‐Fe₂O₃ samples were studied and analyzed, which indicated that the sensitivity of the three samples followed the order of octadecahedral NPs > cop‐hexahedral NPs > op‐hexahedral NPs due to the combined effects of specific surface area and oxygen defects in the nanocrystals.     

Novel cyromazine imprinted polymer applied to the solid-phase extraction of melamine from feed and milk samples

A water compatible molecularly imprinted polymer (MIP) using cyromazine as a mimic template, methacrylic acid as the functional polymer and ethylene glycol dimethacrylate as the cross-linker was synthesized and used to extract melamine from feed and milk samples via a molecularly imprinted solid-phase extraction (MISPE) protocol. Optimum retention of melamine on the MISPE cartridge was achieved using methanol, and the interferences in the samples were effectively washed out. The binding capacity of the polymer toward melamine was found to be about 500 μg of melamine/g of polymer. The recoveries of 2 μg and 20 μg melamine standard spiked into water extract of blank feeds and milk samples were between 83.4% and 103%, with relative standard deviation <5.6%. The cyromazine-MIP demonstrated high cross-reactivity for melamine and low affinity to cyanuric acid. The ionic bond interaction was regarded as the main factors that dominated the retention of the melamine on the MISPE cartridge.     

The Study of Full Light Speech Signal Collection System

The demodulation character of 3×3 optic fiber couplers is analyzed, and the application in the coherent communication system and speech signal collection is pointed out in the paper. By the experiment, the feasibility of speech signal collection system by the way of the all light is verified.     

The Study of Full Light Speech Signal Collection System

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合成化学——新世纪再创辉煌

合成化学这门古老的学科虽然在科学新词爆炸的今天已很少出现在新闻中,但它却是20世纪以来一门常新常青的重要学科,已成长为化学这门中心科学的中心,至今仍在不断地萌发新的方向和目标,创造新的机遇和挑战.在新世纪到来之际,合成化学更以其独特的创造性和兼容性再次成为现代高科技队伍中的重要一员.     

取代苯基呋喃甲酸长链烷基酯的合成及生物活性

取代苯基呋喃甲酸长链烷基酯的合成及生物活性司宗兴＊孙亚秋汪海涛（中国农业大学应用化学系北京１０００９４）关键词苯基呋喃甲酸酯，合成，杀菌活性１９９６－０６－１７收稿，１９９６－１２－０５修回取代芳基呋喃甲酸是一类很好的活性基团，它的酯在医学上用做镇痛...