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含全氟烃基的联苯酯类液晶的合成及其介晶性 总被引:2,自引:0,他引:2
全氟烃或半氟烃链无手性液晶化合物可能呈现铁电液晶性, 具有较大的学术及应用价值而受到研究人员的重视. 合成了全氟己基苯甲酸联苯酯类液晶化合物: ROC6H4C6H4O2CC6H4C6F13 (3a~3e), C3H7C6H4C6H4O2CC6H4C6F13 (6a)及其烃衍生物. 用差示扫描量热法(DSC)和偏光显微镜(POM)对其介晶性研究发现: 烃衍生物呈有序度较低的向列相, 熔点较高, 清亮点较低, 液晶相较窄. 全氟烃基取代的化合物出现多个有序度较高的近晶相, 熔点较低, 清亮点高, 介晶相温度范围宽. 相似文献
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本文以高职院学生信息素质教育的培养目标为出发点,提出了大学生信息素质教育课程"网络化"体系设计的总体原则,在此基础上,设计了大学生信息素质教育课程体系,并对课程的总体框架和几个模块的教学目标和教学内容进行了具体设计,对模块化课程设计中特别需要注意的问题进行了探讨和阐述。 相似文献
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本文介绍了AAL5用作计算机分组数据适配功能时的功能模型、业务特性、原语及有关帧格式,并讨论了AAL5的应用和简单的传送过程。 相似文献
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实时监测心脏病患者的脉搏信号,可减少心血管疾病的发病率,降低死亡率。本文针对心脏病的突发状况以及当前心率监测时有线信号采集方式的不足,设计了基于蓝牙技术的心率监测与无线传输系统,以MSP430单片机为主控制器来控制传感器模块、蓝牙模块、报警模块,实现对脉搏信号的实时监测。实验结果表明,该系统硬件、软件设计方案合理,功耗... 相似文献
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Small change in chemical structure of discotic liquid crystals can cause big difference in their mesomorphism. Replacing of the alkoxy peripheral chains of triphenylene by oxygen-atom containing ester chains would result in novel mesomorphism. A series of mixed tail triphenylenes containing propoxyacetyloxy and alkoxy, abbreviated as C18H6(OCnH2n+1)3(OCOCH2OC3H7)3, n=4-8, and hexa(propyloxyacetyloxy)triphenylene, C18H6(OCOCH2OC3H7)6 were synthesized. Thermal gravimetry analysis (TGA) of three discogens showed that they had good thermal stability till 350 ℃. The mesomorphism was investigated through differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The preliminary X-ray diffraction (XRD) results of one compound showed that it exhibited ordered hexagonal columnar (Colho) mesophase. These mixed tail triphenylene derivatives possessed much stable Colho mesophase and wider mesophase ranges than their hexaalkoxytriphenylene C18H6(OR)6 and hexaalkanoyloxytriphenylene C18H6(OCOR')6 analogues. The asymmetrical compounds 2,6,11-trialkoxy-3,7,10-tri(2-propyloxyacetyloxy)triphenylenes with n=5-8 displayed higher clearing points and wider temperature ranges than their symmetrical isomers 2,6,10-trialkoxy-3,7,11-tri(2-propyloxyacetyloxy)- triphenylenes, while C18H6(OCOCH2OC3H7)6 had the highest clearing point due to the β-oxygen-atom effect. 相似文献
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ATM网络的信令系统是参照ITU-TQ.93B建议来实现的,它通过AAL5进行适配以进入ATM网络,此时的AAL称为信令AAL(SAAL),它由业务特定协调功能(SSCF),业务特定面向连接协议(SSCOP),公共部分汇聚子层(CPCS)和分段重装子层(SAR)组成,本文着重介绍了SSCF、SSCOP的原语、帧格式、状态转移图和有关的操作。 相似文献
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