攀枝花苏铁自然保护区野生居群遗传多样性ISSR分析

采用ISSR分子标记技术对四川省攀枝花苏铁自然保护区的攀枝花苏铁自然居群进行了遗传多样性分析.对采集的48个体的基因组DNA进行PCR扩增,筛选出13个扩增条带清晰的引物,共检测到104个清晰位点,其中多态位点94个,多态位点百分率为90.38%.平均每个引物扩增条带为8条.结果表明,攀枝花苏铁在居群内水平上仍保持较高的遗传多样性.对其居群遗传多样性和遗传结构进行分析,可为攀枝花苏铁的保护和利用提供理论基础.     

A preliminary study of chronology for a newly-discovered ancient city and five archaeological sites in Lop Nor,China

In the past century, it has long been debated in the archeological, historical, geographical, and many other related communities where the capital of the Luolan and Shanshan states was in the Lop Nor region. This paper presents three AMS radiocarbon ages from a newly-discovered ancient city at about 6.3 km to the northwest of the Xiaohe Graveyard, and fifteen new radiocarbon ages from the Loulan (LA), LE, Qieerqiduke, Milan, and Tuyin sites in Lop Nor. The new investigation shows that the age of newly-disco...     

生物柴油/柴油混合燃料喷油提前角优化

为了得到使用生物柴油/柴油混合燃料的最佳喷油提前角,对不同角度混合燃料的燃烧和排放特性进行了研究。结果表明:喷油滞后(提前),燃烧压力、压力升高率与瞬时燃烧放热率降低(增加),曲线后移(前移)。NOx排放降低(增加),且随着负荷的增加,降低(增加)的幅度增大。原机条件下混合燃料烟度最低,喷油提前和滞后都会引起烟度的增加。喷油适当滞后(降低3°)可以在烟度增加不多的情况下有效控制生物柴油/柴油混合燃料的NOx排放,同时压力升高率的降低会使发动机工作更加柔和。     

以经济为基础的图书出版种数预测模型研究及完善

分析了当前图书出版种数预测模型存在的缺陷,以经济基础决定上层建筑和哈佛学派实证研究的SCP理论为基础,结合回归分析和概率学的数理方法,提出了以经济因素为自变量的预测模型以及利用预测置信度的概念修正预测结果的表达方式。     

当前世界女子平衡木项目成套动作难度特征的分析

文章以第40届世锦赛和第29届奥运会女子平衡木单项决赛前8名运动员成套动作为研究对象,采用了文献资料法、录像比赛技术统计等方法.结合2006年版<女子竞技体操评分规则>,对成套难度运用情况进行统计与分析,归纳其特征.     

(NH3)2(H2O)4团簇结构的密度泛函理论研究

利用经验势得到(NH3)2(H2O)4团簇的初始结构,在初始结构的基础上利用DFT/B3LYP/6-31G(d)进行几何结构优化和频率计算.在此基础上挑选出稳定的构型利用DFT/B3LYP/6-311++G(d,p)进行优化.得到了(NH3)2(H2O)4团簇的16种稳定异构体,通过对这些异构体的键长,振动频率,偶极矩的研究,发现了结构对称性好,键长较短的构型能量较低,结构较稳定.     

Controllable fabrication of Au micro/nanostructures on self-doped polyaniline nanofibers via electrochemical deposition and its application for DNA immobilization

Four electrochemical methods, cyclic voltammetric deposition, potentiostatic electrodeposition, multi-potential step electrodeposition and three-step electrodeposition, were used to fabricate Au micro/nanostructures on self-doped polyaniline nanofibers-coated glassy carbon electrodes (Au/nanoSPAN/GCEs). The Au micro/nanostructures deposited on the nanoSPAN-modified electrodes were shown by scanning electron microscopy to exhibit different morphologies, such as Au nanoparticle clusters, monodisperse nanoparticles and homogeneously dispersed flower-like microparticles, depending on the deposition method. This phenomenon demonstrates that control over the morphology of Au metal can be easily achieved by adjusting the electrodeposition method. The electrochemical behaviors of the Au/nanoSPAN/GCEs also varied with above four methods, which were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. In comparison with Au nanoparticle clusters and monodisperse Au nanoparticles, homogeneously dispersed flower-like Au microparticles had the largest surface area and obviously enhanced electrochemical response towards the redox reactions of [Fe(CN)₆]^3?/4? on the modified electrode. DNA immobilization on the Au/nanoSPAN/GCEs was investigated by differential pulse voltammetry using [Fe(CN)₆]^3?/4? as an indicator. The efficiency of DNA immobilization was inherently related to their different Au micro/nanostructure morphologies. The Au/nano-SPAN/GCE fabricated by three-step electrodeposition showed the largest capacity for immobilization of single stranded DNA, which makes it a promising DNA biosensor.     

Network analysis of protein-protein interaction

Residue networks are constructed by defining the residues as the vertices and atom contacts between them as the edges. The residue network of a protein complex is divided into two types of networks, i.e. the hydrophobic and the hydrophilic residue networks. By analyzing the network parameters, it is found that the correct binding complex conformations are of both higher sum of the interface degree values and lower characteristic path length than those incorrect ones. These features reflect that the correct bind-ing complex conformations have better geometric and/or residue type complementarity, and the correct binding modes are very important for preserving the characteristic path lengths of native protein complexes. In addition, two scoring terms are proposed based on the network parameters, in which the characteristics of the entire complex shape and residue type complementarity are taken into account. These network-based scoring terms have also been used in conjunction with other scoring terms, and the new multi-term scoring HPNCscore is devised in this work. It can improve the discrimination of the combined scoring function of RosettaDock more than 12%. This work might enhance our knowledge of the mechanisms of protein-protein interactions and recognition.     

虎纹蛙肌肉挥发性风味成分的分析

采用顶空固相微萃取(HS-SPME)法提取虎纹蛙肌肉中的挥发性风味成分,并利用气相色谱-质谱联用(GC-MS)技术对提取的风味成分进行了分离鉴定,共鉴定出50种化合物,包括醛类、酮类、醇类、芳香烃类、酸类、呋喃类、酯类、酚类和含硫化合物等,其中醛类化合物的含量最高,占总量的63.50%.3-甲基丁醛、己醛、(Z)-4-庚烯醛、(E,Z)-2,4-癸二烯醛、(E,E)-2,4-癸二烯醛、苯甲醛、1-辛烯-3-醇、2,3-戊二酮、2,3-辛二酮、2-戊基呋喃、乙酸乙酯和二甲基三硫等可能是构成虎纹蛙肌肉特征风味的重要挥发性物质.