基于线粒体co I 基因探讨无尾目10个科的分子系统关系

运用PCR技术和相关生物软件，对大头蛙Limnonectes kuhlii和脆皮大头蛙Limnonectes fragilis的线粒体coⅠ基因全序列进行了测定与分析．结合GenBank上已公布的无尾目10个科22个物种的同源序列，以爬行纲楔齿蜥Sphenodon punctatus和密河鳄Alligator mississippiensis为外群，基于核苷酸序列（选取前两位密码子）和氨基酸序列两种数据形式，分别构建NJ树和MP树．结果表明：系统树将无尾目10个科分为两大支，一支为新蛙亚目Neobatrachia的5科15个物种，一支为古蛙亚目Archaeobatrachia的5个科9个物种（其中包括锄足蟾科Pelobatidae和负子蟾科Pipidae），并推测这两个亚目均为单系群．古蛙亚目一支内的盘舌蟾科Discoglossidae与铃蟾科Bombinatoridae亲缘关系较近；新蛙亚目内蟾蜍科Bufonidae与雨蛙科Hylidae，蛙科Ranidae与树蛙科Rhacophoridae两两亲缘关系较近．蛙科中泽陆蛙Fejervarya limnocharis与大头蛙属3个种首先形成姐妹群，表明其较近的亲缘关系，同时推断大头蛙与福建大头蛙Limnonectes fujianensis亲缘关系近于脆皮大头蛙．     

First Total Synthesis of 12-Hydroxy-13-methylpodocarpa-9, 11, 13-trien-3-one

12-Hydroxy-13-methylpodocarpa-9, 11, 13-trien-3-one 9 was isolated from the twigs ofCroton salutaris1. Many diterpenes exhibit significant bioactivities, such as antibac-terial and antitumour and 9 has a rare structure. In order to study the relationshipb…     

广义风险过程中渐近方差的非参数估计

本文对广义风险过程中的渐近方差作了非参数估计,得出并证明了两个定理,为广义风险过程中破产概率的区间估计作了理论准备．     

垂直低温两相流管底液氮汽泡上升速度的实验研究

本文对垂直低温两相流管底部液氮汽泡的上升速度运用高速摄像机进行了可视化实验研究,对所采集的实时图像进行处理.在Cole和Mendelson汽泡上升速度经验公式的基础上,通过对液氮汽泡的上升速度的分析,提出了圆管管路底部液氮汽泡的上升速度的拟合公式,分析研究其变化规律,为进一步探求圆管内液氮弹状汽泡的生成机理提供依据.     

A Fully Vectorial Effective Index Method for Accurate Dispersion Calculation of Photonic Crystal Fibres

A fully vectorial effective index method is developed for accurate dispersion calculation of photonic crystal fibres （PCFs）. In order to improve the accuracy of the model, different values for the effective core radius are used when PCFs have different fibre parameters. The accuracy of our approach is demonstrated by comparing our results with other numerical and experimental results reported in literature. It is found that the accuracy of the fully vectorial effective index method is improved and our results agree well with accurate numerical results obtained by other methods as well as the previously reported experimental data.     

Effect of Molecular Weight on Liquid Crystal Photoalignment by Photosensitive Polyester Containing Thrifluoromethyl Moieties

We investigate the liquid-crystal （LC） alignment direction on photoalignment films formed from photosensitive polyester containing thrifluoromethyl moieties （PPDA） with various molecular weights by crossed polarized optical microscopy. It is found that LC alignment behaviour changes with molecular weight of PPDA. The LC alignment on PPDA irradiated films with the highest molecular weight is homogeneous, while those with low and intermediate molecular weights are homeotropic. However, surface morphologies show weak dependence on molecular weight. The surfaces are smooth and there is no clear morphological anisotropy on these aligned films observed by an atomic force microscope. The surface energies of the irradiated films are also measured by using an indirect contact-angle method where both surface energy and its polar component, increase with increasing molecular weight. Different polar surface energies can be considered as a main reason for different alignment characteristics.     

用分光光度法测定蜂胶超临界CO2萃取物中总黄酮含量

利用碱性条件下黄酮与Al3 生成粉红色络合物在可见光区510 nm处有最大吸收的特性,以芦丁为标样,采用分光光度法测定蜂胶超临界CO2萃取物中总黄酮含量,并与HPLC标准方法测定结果进行比较,发现各平行样的测定结果基本一致,最大偏差为268.38 mg/100 g,最小偏差为52.77 mg/100 g.该法简便快捷,结果相对准确,可作为蜂胶超临界CO2萃取物中总黄酮含量快速评估的一种方法.     

PPG侧链修饰聚酰亚胺的制备与表征

以可溶性聚酰亚胺为反应底物，经氯甲基化反应制得氯甲基化聚酰亚胺，再以氯甲基为活性反应中心，在聚酰亚胺侧链上接枝聚丙二醇单丁醚（PPG），从而得到PPG侧链修饰聚酰亚胺．所制备的产物结构经红外光谱和核磁共振氢谱得以证实．介电常数及吸附脱附测试结果表明：经过大体积侧链PPG修饰后，聚合物的介电常数明显降低，由3．147降低至2．976；比体积和比表面积增大．同时，所制得的聚合物具有优良的溶解性能，在微电子工业中易于加工应用．     

猪肉中16种性激素的多残留检测方法

采用安捷仑GC/MS5975N能同时对猪肉中16种性激素残留进行筛选、定量和确证.对5.0g肌肉样品的检出限均在0.25～1.0 μg·kg-1之间.猪肉的平均回收率分别为83.7%～107.9%,平均变异系数为6.8%～19.7%.当添加水平为1.0 μgkg-1时,本方法不同批次猪肉回收率的相对标准偏差为7.7%～21.6%,重复性好.另外,与安捷仑GC/MS5973分析相比,采用GC/MS5975N时,雌三醇衍生物定量离子为m/z 876,比m/z 663峰度强.     

锥形模圆柱体超塑性挤压非局部摩擦分析

为了考虑金属材料表面微凸结构对模具与工件接触区域上的非局部摩擦效应,在锥形模圆柱体超塑性挤压加工分析中,采用Oden等提出的非局部摩擦定律代替经典的库仑摩擦定律,利用主应力法或工程法建立了相应问题的积微分形式的力平衡方程.在简化的情况下,采用摄动法求得所论问题的近似解,并分析了影响应力的非局部效应的相关因素.