[5-(芳亚甲基氨基)-1,3,4-噻二唑-2-基]硫乙酰芳胺的合成及 生物活性研究

在K2CO3存在下利用聚乙二醇-400 (PEG-400)作相转移催化剂, 于固-液相转移催化条件下, 通过5-芳亚甲基氨 基-2-巯基-1,3,4-噻二唑与氯乙酰芳胺的硫烷基化反应, 合成了16个未见文献报道的[5-(芳亚甲基氨基)-1,3,4-噻二唑-2-基]硫乙酰芳胺衍生物. 经元素分析, FT-IR,1H NMR和13C NMR确证了其结构. 生物活性实验结果表明, 部分化合物对小麦幼苗的生长具有明显的植物生长调节活性, 并对枯草杆菌具有一定的抑制活性.     

微波促进的N-取代2,3,3a,4,7,7a-六氢异吲哚-1,3-二酮的Beller法合成

A rapid and facile synthesis of N-substituted 2,3,3a,4,7,7a-hexahydroisoindole-l,3-dione derivatives via microwave-promoted Beller three-component domino reaction of α,β,-unsaturated aldehydes, amides and N-substituted maleimides was described.     

基于多分辨分析的沪深股市相关性分析

为了有效地揭示沪深股市不同交易周期股票交易的相关性,本文采用极大重叠离散小波变换,将上证指数和深圳成指高频收益率分解在不同的交易周期上,对各个周期的收益率采用semi-GPD模型作为其边缘分布分别进行拟合,在此基础上采用Copula函数方法建立同周期收益率的联合分布,度量了沪深两市同周期交易的相关性.实证表明,不同交易周期所表现出的相关性存在明显差异,并且随着交易期的增长,沪深两市非对称结构逐步明显。     

COMPONENT ALLEE EFFECTS AND STAGE‐SPECIFIC PREDATION: A BRIEF INSIGHT INTO CONSERVATION AND BIOLOGICAL CONTROL ISSUES

In this paper, we propose a two‐stage structured population model subject to component Allee effects in fecundity and maturation, and with two disturbances (predation only and harvest and predation) acting on both stages. It is shown that this combination leads to a demographic Allee effect—a characteristic that could be exploited in pest biological control, but on the other hand, it represents a bane in conservation biology. The analysis is performed for disturbances with functional responses type 2 and 3, and the models show that they yield qualitatively similar results. This characteristic is discussed from the species conservation and biological control point of view, together with possible extensions of this work.     

Crystal Structure and Conformation of a Bilirubin Ester

Summary. Crystal structures determined for three bilirubin analogs with gem-dimethyl groups at C(10) are reported, including the first X-ray structure of a bilirubin dimethyl ester. Conformation-determining torsion angles and key hydrogen bond distances and angles were compared to those from molecular dynamics calculations. Like other rubins, the component dipyrrinones of the three compounds were found to adopt the syn conformation, with Z-configuration double bonds at C(4) and C(15) and bis-lactam tautomeric structures of the end rings. No large differences in bond lengths and bond angles at C(10) were found, and the crystal structures of the two 10,10-dimethyl rubin acids showed considerable similarity to that of bilirubin: both pigments adopt a folded, intramolecularly hydrogen bonded ridge-tile conformation stabilized by six hydrogen bonds, with an interplanar angle in ridge-tile of 98° and 86°. In contrast, the dimethyl ester is intermolecularly hydrogen bonded in the crystal. Each molecule of the ester has its two syn-Z-dipyrrinones rotated into a conformation syn to the gem-dimethyl group, whereas in the acids they are anti.     

香豆素类化合物的一种新合成方法

香豆素类化合物是一类重要的有生物活性的天然产物,也可用作香料、阻凝剂和三线态光敏剂。用 Meldrum 酸合成该类化合物,已有一些报道。我们在研究 Meldrum 酸系列     

Synthesis and spectroscopic properties of 4-(4-carboxyphenyl)-3,3′,5′-trimethyl-2,2′-pyrromethen-1,1′-BF2 complex and its methyl ester

A new, strongly absorbing red dipyrrole chromophore 1 suitable for exciton coupling studies has been synthesized and shown to exhibit an intense absorption (?? 57,000) at λ (max) ?520 nm and a strong fluorescence at λ (em) ?555 nm.     

全局特征及弱尺度融合策略的小样本语音情感识别

语音是一种短时平稳时频信号,因此大多数的研究者都通过分帧来提取情感特征。然而,分帧后提取的特征为局部特征,无法准确反应情感语音动态特性,故单纯采用局部特征往往无法构建鲁棒的情感识别系统。针对这个问题,先在不分帧的语音信号里通过多尺度最优小波包分解提取语句级全局特征,分帧后再提取384维的语句级局部特征,并利用Fisher准则进行降维,最后提出一种弱尺度融合策略来将这两种语句级特征进行融合,再利用SVM进行情感分类。基于柏林情感库的实验结果表明本文方法较单纯使用语句级局部特征最后识别率提高了4.2%到13.8%,特别在小样本的情况下,语音情感识别率波动较小。     

Equivalent properties of single event burnout induced by different sources

The experimental results of single event burnout induced by heavy ions and 252Cf fission fragments in power MOSFET devices have been investigated. It is concluded that the characteristics of single event burnout induced by 252Cf fission fragments is consistent to that in heavy ions. The power MOSFET in the ＂turn-off＂ state is more susceptible to single event burnout than it is in the ＂turn-on＂ state. The thresholds of the drain-source voltage for single event burnout induced by 173 MeV bromine ions and ^252Cf fission fragments are close to each other, and the burnout cross section is sensitive to variation of the drain-source voltage above the threshold of single event burnout. In addition, the current waveforms of single event burnouts induced by different sources are similar. Different power MOSFET devices may have different probabilities for the occurrence of single event burnout.     

利用浅海声场干涉条纹反演海底参数方法研究

浅海频散特性导致声场在距离-频率平面形成干涉条纹,该干涉条纹蕴含着声源以及海底信息。本文通过降噪、滤波等方法,提取船舶辐射噪声干涉条纹中距离域干涉准周期、波导不变量以及去扩展衰减系数(不考虑扩展损失后接收到噪声级随距离的衰减程度)三种特征量的观测值,基于无限均匀沉积层海底模型,采用简正波计算程序理论计算上述三种特征量作为拷贝,提出一种以模拟退火法作为搜索寻优策略的新的匹配反演海底参数的方法。海试数据处理结果表明,该方法反演估计所得海底密度、声速、衰减系数三参数用于浅海负跃层条件下的声场预报效果比较良好。