茜素S复合铋膜电极电催化还原氯霉素

本研究采用电化学法制备茜素S复合铋膜修饰玻碳电极,利用循环伏安法、差示脉冲伏安法(DPV)研究氯霉素在茜素S复合铋膜电极上的电化学行为,并对其电化学测试条件进行优化.在pH 7.0的KH2PO4-Na2HPO4缓冲溶液中,氯霉素在-0.63 V处产生一灵敏的不可逆还原峰,显示出复合铋膜对氯霉素的还原有很好的催化作用.D...     

食品中铝检测方法研究进展

介绍了食品中铝的来源,并综述了近十年中食品中铝测定方法的研究进展,包括电感耦合等离子体原子发射光谱法、电感耦合等离子体质谱法、石墨炉原子吸收光谱法、电化学分析法以及分光光度法等方法(引用文献75篇)。     

数据挖掘技术及应用

随着信息技术的迅速发展,数据库的规模不断扩大,而传统的查询、报表工具无法满足挖掘有效信息的需求,因此,需要一种新的数据分析技术处理大量数据,并从中抽取有价值的潜在知识,即数据挖掘技术。     

一种虚拟路由冗余协议负载均衡技术实现机制

标准VRRP（虚拟路由器冗余协议）解决在配置默认网关环境下消除网络单点故障问题,其协议自身不够灵活,即虚拟路由器中只有主设备进行流量转发,其他备用设备均作为备份不进行流量转发,无法负载分担,不能最大程度提高带宽和设备利用率。针对该局限,在此基于与某公司的合作项目,论述了一种虚拟路由冗余协议负载均衡实现机制,在标准VRRP协议分析研究基础上引入虚拟转发器和转发状态机,实现一个虚拟IP对应多个虚拟MAC的机制,无需配置多个备份组就能同时实现路由冗余备份和流量负载均衡,使局域网内用户能够通过每台虚拟转发器与外界通信,极大地提高资源利用率,最后以实验验证了设计可行性。     

基于数字全息干涉术测量液相云微物理起伏的湍流参数表征

针对云降水物理研究中湍流的测量需求,提出了一种基于数字全息干涉术测量液相云微物理起伏的湍流参数表征方法.该方法无需假设云滴谱分布函数及调整相关参数即可获得实际湍流影响的液相云微物理起伏.利用定常湍流影响的雾滴模拟液相云滴,采用像元尺寸1.67μm的相机时序记录雾滴谱,获得含水量与雾滴平均半径的起伏.根据湍流理论,计算了...     

SYNTHESIS AND MESOMORPHIC PROPERTIES OF FISHBONE-LIKE LIQUID CRYSTALLINE POLYSILSESQUIOXANES——Ⅰ. FISHBONE-LIKE, β-DIKETONE-BASED LIQUID CRYSTALLINE POLYSILSESQUIOXANES AND THEIR COPPER COMPLEXES*

Two kinds of fishbone-like, β-diketone-based liquid crystalline polysilsesquioxanes(FBDKLCP'S), homopolymeric (H-FBDKLCP) and copolymeric (C-FBDKaLCP) have been first synthesized via the hydrosilylation reaction of a vinyl-terminated β-diketone with the homopolymeric ladderlike polyhydrosilsesquioxane (LPHSQ) and random copolymethylhydrosilsesquioxane (LRPMHSQ) respectively. These new kinds of FBDKLCP with M of 10~4 is thermotroic liquid crystalline polymer and its clearing temperatures T_i's and mesophase range △T's are much higher than those of the corresponding comb-like β-diketone liquid crystalline polysiloxane (DKLCP) by about 200℃. Similar results have been observed with the comparison of the two different structure Cu-coordinating compounds The significant increases in T_((?))'s and △T's of the FBDKLCP and Cu-FBDKLCP are mainly attributed to the great rigidity of the ladderlike polysilsesquioxane backbone.     

SYNTHESIS AND-CHARACTERIZATION OF THE SOLUBLE, HIGH MOLECULAR WEIGHT AND LADDERLIKE POLYHYDROSILSESQUIOXANE AND ITS COPOLYMERS

The high molecular ladderlike polyhydrosilsesquioxane (LPHSQ) and its copolymer, ladderlike random copolymethylhydrosilsesquioxane (LR-PMHSQ) and ladderlike block copolymethylsilsesqui-oxane(LB-PMHSQ) have been synthesized by a preaminolysis reaction of the corresponding trichlorosilane with 1 ,4-phenylene diamine(PDA) then by hydrolysis and polycondensation reactions The thermographs of these polymers measured by DSC method indicate that these macromolecular backbones are very rigid as seen from the DSC curves which are almost horizontal from room temperature until 350 ~C without noticeable glass transition. The content of Si—H group in the polymers can be regulated by changing the composition of the two copolymerized monomers. So the ladderlike polymers including its copolymers can be the useful precursors for the functional polymers, especially such as fishbone-like liquid crystalline polymers.     

多媒体编码压缩的分类、原理和技术

数据压缩 ,通俗地说 ,就是用最少的数码来表示信号 ,这是多媒体的核心技术。其作用是 :能较快地传输各种信号 ,如传真、Modem通信等 ;在现有的通信干线并行开通更多的多媒体业务 ,如各种增值业务 ;紧缩数据存储容量 ,如CD -ROM、VCD和DVD等 ;降低发信机功率 ,这对于多媒体移动通信系统尤为重要。由此看来 ,通信时间、传输带宽、存储空间甚至发射能量 ,都可能成为数据压缩的对象。1　数据压缩方法的分类数据压缩方法种类繁多 ,主要的压缩编码方法与分类如图 1所示 ,可以分为无损压缩和有损压缩两大类。图 1　主要的数据压缩方法与分类无…