Friedel–Crafts alkylation between chalcone epoxides and heteroarenes induced by triarylaminium salt

Triarylaminium salt was disclosed as a highly efficient nonmetallic initiator for the Friedel–Crafts reaction between chalcone epoxides and heteroarenes to construct a series of complex β-heteroaryl α-ketols in mild conditions and with good yields. Chalcone epoxides were presented as valuable halogen-free pre-electrophile in Friedel–Crafts alkylation through the formation of the stabilized benzylic cation intermediates. A plausible radical cation chain mechanism was also proposed.     

由从属关系定义的亚纯多叶函数的子类的某些性质

In the present paper, we introduce some new subclasses of meromorphic starlike,convex, close-to-convex and quasi-convex functions of β-reciprocal in terms of the linear operator using subordination. We obtain the coefficient estimates, convolution properties, integral preserving properties and inclusion relationships of the classes. The results presented here include several results as their special cases.     

高速信号采集记录仪设计

针对高速信号实时采集存储的需求,设计了一种高速信号采集记录仪。记录仪通过高速A/D转换器对信号进行采样,并实时存入NAND FLASH存储阵列中。为提高数据存储速率,综合采用并行总线、交错双平面页编程、多级流水线等技术,大幅提升FLASH的写入速度。记录仪可实现8bit、200MSPS的采样速率,并可将速率为200MB/s的采样数据实时存储。     

基于NSCT和仿生模式的人脸图像识别方法

针对现有的人脸图像识别算法准确度不高的问题,提出了一种基于非下采样Contourlet变换(NSCT)和仿生模式的人脸图像识别的方法。对人脸图像进行NSCT分解,并将分解后的各系数矩阵转化为能量特征,利用仿生模式识别算法实现对人脸图像的识别。使用UMSIT、Yale和ORL人脸库进行实验,且设计了无拒识和有拒识两组方案,实验结果表明:与传统方法相比,利用基于非下采样Contourlet变换和仿生模式的人脸图像识别的方法能够获得更高的正确率,而有拒识的方案能够获得更好的综合性能。     

定向红外对抗系统与技术的发展

红外对抗系统与技术经历了近半个多世纪的发展,先后出现了红外干扰机、红外诱饵及红外烟幕等几类红外干扰技术,并形成了一个庞大的红外干扰器材家族.近年来,随着红外成像寻的制导武器和技术的发展,常规的红外干扰手段对新型红外制导武器的干扰效果越来越不尽人意,人们逐渐提出了以高功率氙灯或激光作为红外能量源的定向红外对抗(DIRCM)概念.该系统具备优越的红外干扰性能,如通过干扰、致眩和毁伤等干扰红外成像导引头、多次重复使用、干扰效率高等,现已成为新一代红外对抗系统的优选方案.回顾了近年来国外新一代定向红外对抗系统和技术的研究发展历程,重点阐述了基于激光的定向红外对抗系统的工作原理、干扰毁伤机理、在技术上的优势及其国外发展现状,预测了定向红外对抗系统与技术的发展趋势.     

Preparation and Characterization of Polyhydroxyurethane/Attapulgite Nanocomposites Via In-Situ Surface-Initiated Polymerization

The polyhydroxyurethane/attapulgite nanocomposites (PHU/ATP) were prepared by in-situ surface-initiated polymerization of a five-membered cyclic carbonate, 2, 2-bis [p-(1, 3-dioxolan-2-one-4-yl-methoxy) phenyl] propane (B5CC) and hexamethylene diamine, from the surface of the aminopropyl attapulgite nanoparticles (APATP) for the first time. The chemical grafting of the polymer on the surface of ATP was confirmed by FTIR and the morphology of the attapulgite nanoparticles in the nanocomposites was examined by TEM. The thermal stabilities of the polyhydroxyurethane (PHU) and the polyhydroxyurethane/attapulgite nanocomposites (PHU/ATP) were compared with thermogravimetric analysis (TGA).The %G of the attapulgite nanoparticles was also calculated from the results of TGA after the free polyhydroxyurethane was washed off.     

顺序注射氢化物发生-原子荧光光谱法同时测定环境水样中砷和镉

目的考察了光电倍增管负高压、砷和镉灯电流、原子化器高度、载气流量、屏蔽气流量、增敏剂等因素对测定结果的影响。方法建立一种顺序注射氢化物发生-原子荧光光谱法同时测定水样中砷和镉含量的方法。结果载流HCl的浓度为0.60 mol/L,KBH4质量浓度为20g/L,增敏剂硫脲和钴离子的质量浓度分别为80 g/L和70 g/L时,同时测定砷和镉的效果最佳。在最佳实验条件下,砷和镉的检出限分别为0.009 3μg/L和0.12μg/L,加标回收率为92.3%～103.9%,相对标准偏差小于3.5%,被测水样中共存离子对砷和镉的测定没有干扰。结论该法操作方便、快速,用于环境水样中砷和镉的同时测定,具有很好的可行性和实用性。