隔振沟对爆炸塔周边地表振动的影响

对内径2m、壁厚0.4m 的椭球封头爆炸塔进行有、无隔振沟条件下的对比爆炸实验,并监测塔体 周边6个测点的地表竖向及水平方向的振动速度。研究结果表明:地表质点的振动持续时间小于0.2s,竖向 振动频谱在20~500Hz范围内,水平方向振动频谱则在200~800Hz范围内;隔振沟使水平方向振动幅度衰 减至原来的1/10,对竖向振动幅度衰减至原来的1/4~1/3,对地表振动频率无明显影响;爆炸塔隔振沟的深 度为1m 时,对爆炸地震波无任何衰减作用,仅当深度达到1.5~2.0倍瑞利波波长时(5.6~7.5m)才会产 生明显的隔振效果。     

钯纳米粒子@超顺磁性Fe3O4催化的Heck偶联反应

利用Fe3O4溶胶的正电荷特性,将络负离子PdCl 24-通过静电作用吸附在Fe3O4胶体粒子表面,以抗坏血酸(Vc)进一步将其还原,即得到负载有Pd金属团簇的Fe3O4胶体粒子(Pd0@Fe3O4).该超顺磁性Fe3O4载体负载的纳米Pd对Heck反应表现出良好的催化活性,且反应完毕后可简单地通过永久磁铁将催化剂从反应体系中分离,循环使用.研究表明,该催化剂在循环使用5次后反应活性没有明显下降,并对多种卤代芳烃的Heck偶联反应表现出优异的催化活性.     

SYNTHESIS AND CHARACTERIZATION OF ORGANO-SOLUBLE FLUORINATED POLYIMIDES FROM 4,4′-BIS(3-AMINO-5-TRIFLUOROMETHYLPHENOXY)-BIPHENYL AND VARIOUS AROMATIC DIANHYDRIDES

An aromatic diamine monomer, 4,4′-bis(3-amino-5-trifluoromethyl phenoxy)-biphenyl (TFBPDA), was synthesized via the nucleophilic displacement reaction of 3,5-dinitrobenzotrifluoride and 4,4′-biphenol. The monomer was reacted with various aromatic dianhydrides via the high temperature polycondensation procedure to provide a series of polyimides. The polyimides, PI-1 to PI-4, show good solubility not only in aprotic solvents, such as N-methyl-2-pyrrolidinone and N,N-dimethylacetamide, but also in many common solvents, such as m-cresol, chloroform and cyclopentanone. PI-4, derived from 4,4′-(hexafluoroisopropylidene)diphthalic anhydride and TFBPDA, was even soluble in toluene. Moreover, PI films exhibit good thermal stability, outstanding transparency in the visible light region and acceptable mechanical and electrical properties. The excellent combined properties of the polyimides make them as a good candidate for fabricating microelectronics.     

ORGANO-SOLUBLE FLUORINATED POLYIMIDES DERIVED FROM α,α-BIS(4-AMINO-3,5- DIMETHYLPHENYL)-4''-FLUOROPHENYL METHANE AND VARIOUS AROMATIC DIANHYDRIDES

Organo-soluble fluorinated polyimides were synthesized by the polycondensation of a new aromatic diamine α,αbis(4-amino-3,5-dimethylphenyl)-4'-fluorophenyl methane with several aromatic dianhydrides. The one-step polymerization polyimides could be soluble not only in polar aprotic solvents, such as N-methyl-2-pyrrolidinone, and N,Ndimethylacetamide, but also in common organic solvents, such as chloroform, cyclopentanone, m-cresol and so on. The polyimide films show excellent transparency with the UV-Vis cut-off lengths of 310-360 nm and light transmittances of higher than 80% in the visible region. In addition, the polyimides exhibit good thermal stability with an initial decomposition temperature (Td) higher than 530℃ and have more than 60% of residual weight retentions at 700 ℃.     

HETEROAROMATIC POLYMERS - HIGH TEMPERATURE POLYPYRROLONES DERIVED FROM 2,6-BIS(3′,4′-DIAMINOPHENYL)-4-BIPHENYLPYRIDINE AND VARIOUS AROMATIC DIANHYDRIDES

A new type of aromatic tetraamine containing biphenyl moiety in the side chain was synthesized via a modified Chichibabin's reaction. 3-Nitro-4-acetamidoacetophenone was reacted with 4-phenyl benzaldehyde in the presence of ammonium acetate to obtain 2,6-bis(3′,4′-diaminophenyl)-4-biphenyl pyridine (DPPA). A series of polypyrrolones (PPys)were prepared using tetraamine and various aromatic dianhydrides via a two-step cyclization procedure. All the PPys show excellent high temperature stabilities with the initial decomposition temperatures of 530-549℃ and residual weight ratio of 49%-80% at 750℃ in nitrogen. The polymers exhibit no apparent glass transition temperatures (Tgs) except PPy-1(Tg = 327℃), which is derived from tetraamine DPPA and 2,2-bis[4-(3′,4′-dicarboxyphenoxy)-phenyl]propane dianhydride (BPADA). In addition, the polymers have acceptable mechanical properties with the tensile strength of 65-94 MPa. The PPy films show excellent hydrolysis-resistance in alkaline aqueous medium and could maintain most of the properties even after boiling in 10% aqueous sodium hydroxide solution for a week.     

VoltammetricStudiesontheOxidationandtheElectroanalysisofNitriteIonsatanElectrodepositedThallium（Ⅲ）OxideThinFilmElectrode

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模糊错误逻辑分解转化词与内涵否定词的逻辑关系

在文 [1]的基础上 ,在简单分析现时中错误的传递与转化的实际存在的同时 ,介绍国内外在逻辑研究领域对事物传递与转化规律的研究现状。特别为了探索控制与防范证券风险的技术而主要研究模糊错误逻辑分解转化词与内涵否定词的逻辑关系。     

SYNTHESIS AND CHARACTERIZATION OF ORGANO-SOLUBLE FLUORINATED POLYIMIDES FROM 4,4''''-BIS(3-AMINO-5-TRIFLUOROMETHYLPHENOXY)-BIPHENYL AND VARIOUS AROMATIC DIANHYDRIDES

An aromatic diamine monomer,4,4'-bis(3-amino-5-trifluoromethyl phenoxy)-biphenyl (TFBPDA),wassynthesized via the nucleophilic displacement reaction of 3,5-dinitrobenzotrifluoride and 4,4'-biphenol.The monomer wasreacted with various aromatic dianhydrides via the high temperature polycondensation procedure to provide a series ofpolyimides.The polyimides,PI-1 to PI-4,show good solubility not only in aprotic solvents,such as N-methyl-2-pyrrolidinone and N,N-dimethylacetamide,but also in many common solvents,such as m-cresol,chloroform andcyclopentanone.PI-4,derived from 4,4'-(hexafluoroisopropylidene)diphthalic anhydride and TFBPDA,was even soluble intoluene.Moreover,PI films exhibit good thermal stability,outstanding transparency in the visible light region and acceptablemechanical and electrical properties.The excellent combined properties of the polyimides make them as a good candidate forfabricating microelectronics.     

差分吸收光谱法对大气中挥发性有机物光化学作用指示剂的监测与反演

差分吸收光谱技术 (DOAS)由于高时间分辨率、高灵敏度和低操作费用等特点非常适合对大气中痕量的挥发性有机物 (VOCs)的光化学作用指示剂——O₃,O_x(O₃+NO₂)和HCHO进行实时追踪。 但由于这些指示剂含量较低,测量精度易受干扰。 文章利用自行研制的差分吸收光谱系统,对VOCs的光化学作用指示剂测量方法和数据反演进行了研究,通过增加信噪比,扣除背景杂散光等手段对其进行了准确测量;针对标准吸收截面的温度效应、光谱固有结构和灯谱结构的干扰,改进了干扰的对除方法;并对不同波段反演O₃,NO2和HCHO的干扰因素,反演浓度结果和反演准确度进行了分析与对比,以合适的波段准确反演物质浓度。