高分子量DL-丙交酯的合成及热降解

研究了聚ＤＬ－丙交酯（ＰＤＬＬＡ）的合成及热降解性能。发现影响聚合物分子量的关键因素是单体的重结晶、引发剂的浓度以及安瓿瓶在封管时的干燥和真空度。采用ＤＳＣ、ＴＧＡ分析了ＰＤＬＬＡ的玻璃化转变和热分解。ＰＤＬＬＡ是热不稳定聚合物,影响其热稳定性的主要因素是残留单体、催化剂和低聚物的含量,将聚合物溶解沉淀处理可以延缓其热解速度,提高它的热稳定性。     

N-乙酰丙酮-DL-亮氨酸-水合铜(II)的合成和表征

合成了N 乙酰丙酮 DL 亮氨酸 水合铜 (II) .基于元素分析、摩尔电导、电子光谱、红外光谱和热重—差热分析进行了结构和组成分析 ,N 乙酰丙酮 DL 亮氨酸是负二价的三齿配体 ,配位原子是亚氨基氮、羧基氧和羟基氧原子     

两耳分听汉字测验中大脑机能优势加工的超日节律效应

对３２名听力正常的大学生被试在日间进行连续８ｈ汉语单字词两耳分听测验,以检查大脑两半球加工汉字语音机能优势的时间性动态变化。结果发现：①所有被试左、右耳正确报告的词数未见有明显的周期性波动;②有１２例被试左、右耳正确占先报告词数的优势比出现了周期约为３ｈ的超日节律;③女性被试的平均节律周期长度明显长于男性。结果提示,大脑两半球控制的分听语词加工过程在部分被试中明显受到生物钟超日节律的调节。     

Optimization of the determination of chemical oxygen demand in wastewaters

Chemical oxygen demand (COD) is one of the most relevant chemical parameters for the management of wastewater treatment facilities including the control of the quality of an effluent. The adequacy of decisions based on COD values relies on the quality of the measurements. Cost effective management of the minor sources of uncertainty can be applied to the analytical procedure without affecting measurement quality. This work presents a detailed assessment of the determination of COD values in wastewaters, according to ISO6060:1989 standard, which can support reduction of both measurement uncertainty and cost of analysis. This assessment includes the definition of the measurement traceability chain and the validation of the measurement procedure supported on sound and objective criteria. Detailed models of the measurement performance, including uncertainty, developed from the Differential Approach, were successfully validated by proficiency tests. The assumption of the measurement function linearity of the uncertainty propagation law was tested through the comparison with the numerical Kragten method. The gathered information supported the definition of strategies for measurement uncertainty or cost reduction. The developed models are available as electronic supplementary material, in an MS-Excel file, to be updated with the user's data.     

基于延时处理的对角加载信源数估计方法

为了解决在有色噪声背景下信息论准则算法估计信源数失效以及盖氏圆方法在低信噪比下性能下降的问题,提出了一种利用接收信号延时信息的协方差矩阵对角加载技术估计信源数的方法.首先构造接收信号的延时协方差矩阵,抑制色噪声的影响,然后对延时协方差矩阵做出变换处理,得到抑制噪声后的协方差矩阵特征值,最后对得到的特征值进行对角加载技术处理,利用信息论准则进行信号源数目的估计.仿真结果表明了该算法的正确性和有效性.     

DL-蛋氨酸铋(Ⅲ)固体配合物的合成、表征和XRD数据指标化

许多氨基酸的金属配合物具有抗菌、抗炎、抗癌和拮抗作用等生物活性[1,2 ] 。铋的化合物在医药中也有着广泛的应用 ,如柠檬酸铋用于治疗胃病[3 ] ,某些铋的化合物也用于外科处理创伤和止血 ,为了寻找副作用小、疗效更好的抗溃疡新药 ,我们通过固 固反应合成了ＤＬ 蛋氨酸合铋 (Ⅲ )配合物。利用固相反应合成生物无机配合物 ,可有效地避免某些金属盐的水解 ,具有操作简单、副反应少、产率高等特点[4,5] 。1　实验部分1 1　主要仪器与试剂85 2型恒温磁力搅拌器 (上海司乐仪器厂 ) ,ＤＧＦ30型电热恒温干燥箱 (南京实验仪器厂 ) ,Ｄ2 60型恒…     

D-、L-和DL-缬氨酸晶体低温旋光性研究

由于电弱力宇称不守恒,氨基酸对映体分子间存在宇称破缺能差，通过Z0粒子的介导，在某临界温度下，氨基酸分子会发生类似于BCS(Bardeen-Cooper-Schrieffer)超导的玻色凝聚,引起二级相变,理论推测相变温度约在250 K.本文通过原位测量在240～290 K下， D型、L型和DL型缬氨酸晶体的旋光角随温度的变化，发现D型和DL型缬氨酸晶体在270 K有旋光角跃变， L型缬氨酸晶体的旋光角基本不变，为Salam预言的二级相变提供了直接证据.     

L-苯丙氨酸键合手性配体交换色谱固定相的制备及手性拆分

合成了L-苯丙氨酸键合手性配体交换固定相，用元素分析和红外光谱对固定相进行了表征；该固定相在反相条件下对DL-氨基酸对映体有良好的拆分能力。     

Preparation and mechanical properties of poly(chitosan‐g‐DL‐lactic acid) fibrous mesh scaffolds

DL ‐lactic acid was grafted onto chitosan to produce poly(chitosan‐g‐DL ‐lactic acid)(PCLA) without using a catalyst. These PCLAs were then spun into filaments and further fabricated into fibrous mesh scaffolds using an improved wet‐spinning technique. The diameter of filaments in different scaffolds could vary from a few micrometers to several tens of micrometers. The scaffolds exhibited various pore sizes ranging from about 20 µm to more than 200 µm and different porosities up to 80%. The several main processing conditions were optimized for obtaining the desired scaffolds with well‐controlled structures. The tensile and compressive mechanical properties of the mesh scaffolds in both dry and hydrated states were mainly examined. Significantly improved tensile strength and modulus, enhanced compressive modulus, and stress as well as the dimensional stability for these mesh scaffolds in their hydrated state were observed. Copyright © 2007 John Wiley & Sons, Ltd.     

杯芳烃膜电极研究

用吸附法将 C-十一烷基间苯二酚杯 [4]芳烃固定在玻碳电极上制成杯芳烃膜电极 ,对DL-去甲肾上腺素、尿酸、DL-酪氨酸、邻苯二酚进行了测定 ,该电极对 DL-去甲肾上腺素和邻苯二酚具有良好的响应 ,其线性范围分别为 4.0× 1 0 -5～ 8.0× 1 0 -4 和 2 .0× 1 0 -4 ～ 2 .0× 1 0 -3mol·L-1,检测下限分别为 1 .2 5× 1 0 -5和 1 .0× 1 0 -5mol· L-1,对尿酸、DL -酪氨酸没有响应 ,试验发现杯芳烃膜电极不但具有选择性 ,而且有较快的响应速度、良好的重现性和稳定性。