大环镍(Ⅱ)配合物与扁桃酸的手性识别

外消旋大环镍(Ⅱ)配合物[Ni (rac-L)](ClO₄)₂分别与l-和d-扁桃酸阴离子在乙腈/水溶液中反应,通过手性识别得到六配位的[Ni (_RR-L)(S-Man)]ClO₄(1)和[Ni (SS-L)(R-Man)]ClO₄(2)对映异构体(L=5,5,7,12,12,14-六甲基-1,4,8,11-四氮杂环十四烷,Man=扁桃酸)。当[Ni (rac-L)](ClO₄)₂与dl-扁桃酸阴离子反应时得到一对对映体等量存在的共聚物,其中大环配体中RR和SS构型分别优先与l-和d-Man^- 配位形成外消旋混合物,反应过程中发生了手性识别现象,每颗晶体均为手性对映体。当[Ni (rac-L)](ClO₄)₂分别与结构类似的dl-2-苯基丙酸和dl-托品酸阴离子反应时,分别得到化合物[Ni (rac-L)(dl-PPA)]ClO₄(3)(PPA=2-苯基丙酸)和[Ni (rac-L)(dl-Tro)]ClO₄(4)(Tro=托品酸)。X射线单晶衍射结果表明,4个配合物中Ni (Ⅱ)离子均与折叠大环配体L的4个氮原子和2个来自羧基与羟基的氧原子(1和2),或羧基氧原子(3和4)顺式配位,形成六配位八面体构型。配合物1和2属于一对对映异构体,分别通过[Ni (_RR-L)(S-Man)]⁺和[Ni (SS-L)(R-Man)]⁺分子间氢键作用形成一维之字形链状结构。配合物1和2的单手性特征与圆二色(CD)谱测定结果一致。     

一种采用脉冲串的自适应有源干扰抵消器

在许多应用中，周期性干扰是由旋转的机械设备所产生的。一个周期性信号可以与一个特殊形式的周期性的脉冲串完全相干。本文提出了一种采用脉冲串的自适应有源噪声抵消器(AANC)来抵消周期性干扰，这种抵消器产生一个与干扰信号相同步的周期性的单位脉冲串作为参考输入。将这种有源噪声抵消器和Delayed-X LMS算法相结合，可以大大地减小运算量，并且也可以保证良好的收敛特性。理论分析和计算机仿真验证了本文的结果。     

大环镍(Ⅱ)配合物与扁桃酸的手性识别

外消旋大环镍(Ⅱ)配合物[Ni (rac-L)](ClO₄)₂分别与l-和d-扁桃酸阴离子在乙腈/水溶液中反应,通过手性识别得到六配位的[Ni (_RR-L)(S-Man)]ClO₄(1)和[Ni (SS-L)(R-Man)]ClO₄(2)对映异构体(L=5,5,7,12,12,14-六甲基-1,4,8,11-四氮杂环十四烷,Man=扁桃酸)。当[Ni (rac-L)](ClO₄)₂与dl-扁桃酸阴离子反应时得到一对对映体等量存在的共聚物,其中大环配体中RR和SS构型分别优先与l-和d-Man^- 配位形成外消旋混合物,反应过程中发生了手性识别现象,每颗晶体均为手性对映体。当[Ni (rac-L)](ClO₄)₂分别与结构类似的dl-2-苯基丙酸和dl-托品酸阴离子反应时,分别得到化合物[Ni (rac-L)(dl-PPA)]ClO₄(3)(PPA=2-苯基丙酸)和[Ni (rac-L)(dl-Tro)]ClO₄(4)(Tro=托品酸)。X射线单晶衍射结果表明,4个配合物中Ni (Ⅱ)离子均与折叠大环配体L的4个氮原子和2个来自羧基与羟基的氧原子(1和2),或羧基氧原子(3和4)顺式配位,形成六配位八面体构型。配合物1和2属于一对对映异构体,分别通过[Ni (_RR-L)(S-Man)]⁺和[Ni (SS-L)(R-Man)]⁺分子间氢键作用形成一维之字形链状结构。配合物1和2的单手性特征与圆二色(CD)谱测定结果一致。     

无机硅胶-有机聚合物混合基质C16毛细管整体柱的制备和性能研究

利用具有双功能基团的3-(三甲氧基硅烷)丙基甲基丙烯酸酯在酸性水溶液中硅氧烷水解缩聚后,再在热引发条件下与甲基丙烯酸十六酯进行双键聚合反应,制备了一类新型的无机硅胶-有机聚合混合基质毛细管电色谱整体柱,实现了硅胶基质整体柱和有机聚合基质整体柱制柱方法合二为一.提出了吸汞法控制溶胶混合溶液引入毛细管适当位置,以获得平整的整体柱固定相界面的简易操作方法.优化了整体柱制备条件,采用扫描电镜和氮吸附比表面仪对整体柱材料的结构特征进行了表征,材料平均比表面积为103.4 m2/g,中孔孔径主要分布在3～7 nm范围.探讨了运行电压、缓冲液浓度、pH值和有机改性剂含量等因素对电渗流流速的影响.利用制备柱基线分离了7种中性芳香烃类物质.对萘的柱效达54000塔板数/m;连续运行5次的保留时间的RSD为0.9%, 容量因子的RSD为0.6%;连续运行3 d,保留时间的RSD为1.2%,容量因子的RSD为0.8%;不同批次3支整体柱,保留时间的RSD为8.7%,容量因子的RSD为5.7%.     

Application of movable collimators to the BEPC Ⅱ

BEPC Ⅱ is a double ring e+e-collider with high beam currents and luminosity,so the high beamrelated backgrounds may disturb the detector.In order to have a good quality of data taking,backgrounds should be kept at a level as low as possible.A series of collimators are designed and installed in both the e+and e-rings.Two of the collimators are horizontally movable,each for one ring,about 8 m upstream from the interaction point.Experiments have been done to identify the effectiveness of the movable collimators with different apertures and beam currents.The results show that the movable collimators are very effective and can reduce as much as about 50% of beam-related backgrounds.     

Synthesis and Supramolecular Structure of Chloro（1,10-phenanthroline ）copper（I） Hexahydrate

1INTRODUCTION Atom transfer radical addition is an efficient me-thod for carbon-carbon bond formation in organic synthesis[1,2].In some of these reactions,a transi-tion-metal catalyst acts as a carrier of the halogen atom in a reversible redox process.The transition-metal-catalyzed has been successfully used to con-trol radical polymerization[3].In the process,the transition-metal species initially abstracts halogen atom X from organic halide to form oxidized species and carbon-centered r…     

Application of movable collimators to the BEPCⅡ

BEPCⅡ is a double ring e＋ecollider with high beam currents and luminosity,so the high beamrelated backgrounds may disturb the detector.In order to have a good quality of data taking,backgrounds should be kept at a level as low as possible.A series of collimators are designed and installed in both the e＋ and erings.Two of the collimators are horizontally movable,each for one ring,about 8 m upstream from the interaction point.Experiments have been done to identify the e-ectiveness of the movable collimators with different apertures and beam currents.The results show that the movable collimators are very effective and can reduce as much as about 50% of beam-related backgrounds.     

电化学法制备石墨烯及其导电特性

采用电化学方法将石墨层电解剥离, 得到分散于电解质溶液的结构较为完整的石墨烯. 用透射电子显微镜和拉曼光谱分析了石墨烯的形貌和结构, 利用四探针法测定了石墨烯导电特性. 实验数据和理论拟合结果表明, 当100 K相似文献   

Tunable Infrared Luminescence and Optical Amplification in PbS Doped Glasses

PbS-doped glasses are prepared. Absorption and luminescence spectra show that both the absorption and infrared emission can be tuned widely by thermal treatment conditions. Optical amplification at 1300 nm is observed, and amplified spontaneous emission （ASE） spectrum is also measured to confirm the optical gain from PbS quantum dots.