全球大气重力波联测期间电离层扰动的台阵观测

本文利用武汉电离层观象台的加密频高图和三站Doppler图记录及新近提出的短波扰动反演方法,分析了1985年全球大气重力波联测(WAGS)期间10月18日这天白天的重力波扰动,发现在该日扰动中有两列不同形态的波列分别属于中尺度的内重力波和大尺度的导制重力波。本文还进一步估算了这两列重力波的水平传播参量,深入分析了它们的频谱结构的高度变化特征,发现了重力波功率谱谱峰的分裂和偏移等重要现象。本文结果表明,新的反演方法使电离层无线电汉诊断的简易短波实验系统,也能成为探测和研究重力波一类大尺度电离层动力过程的有效手段。     

多项式理想准素分解的算法

讨论了多项式理想准素分解的算法,对于理想坐标变换中关键的“一般位置”的计算,给出了一个确定算法,并建立了特别规范Groebner基的概念,利用这一概念及文中提供的相应算法,可以方便地计算理想的维数,进而使用降维的方法来得到高维理想的准素分解。     

Reversible 5′-end biotinylation and affinity purification of synthetic RNA

A reversible biotinylation phosphoramidite was synthesized and incorporated onto the 5′-end of an oligoribonucleotide on a solid phase synthesizer. After cleavage and deprotection, the crude synthetic oligomer mixture was incubated with NeutrAvidin^® coated microspheres, and the failure sequences removed by washing with a buffer followed by treating the microspheres with tetrabutylammonium fluoride to give a high quality unmodified full-length oligoribonucleotide.     

单腔并行双器件功率合成理论与实验研究

本文对一种毫米波单腔并行双器件功率合成器进行了理论和实验研究。分析并计算了矩形波导腔内两只并行振荡器件的外电路阻抗,给出了一些对设计、开发该功率合成器非常有用的数值结果。在36.0GHz频率附近,单腔并行双Gunn器件功率合成器的实验结果为:合成输出功率约400mW,合成效率高于95.5％,大于100mW输出的机械调谐带宽近1.5GHz。     

钻石型等级晶格上Gauss模型的临界性质

在Gauss模型中 ,假设Gauss分布常数依赖于晶格格点的配位数 ,并且满足关系bqi/bqj=qi/ qj( qi是格点i的配位数 ,bqi是格点i上的Gauss分布常数 ) .利用重整化群变换和自旋重标相结合的方法 ,研究了一族钻石型等级晶格上Gauss模型的临界行为 .结果发现 :这些晶格的铁磁相变性质属于同一普适类 ,其临界点和临界指数分别为K =b_qi/ q_i 和ν=1 / 2 .     

Electronic Structure and Magnetic Properties of SmCo7-xZrx

The electronic structure and magnetism of SmCo_7-xZr_x alloy are investigated using the spin-polarized MS-X. method. The results show that a few of electrons are transferred to the Sm(5d⁰) orbital due to orbital hybridization between Sm and Co atoms. The exchange interactions between 3d and 5d electrons are more important than the polarization effects of the conductive electrons, thus it is the main reason resulting in the long-range ferromagnetic order in SmCo_7-xZr_x. The Curie temperature of SmCo_7-xZr_x is generally lower than that of corresponding pure Co, which may be explained by the weaker average coupling strength between Co lattices due to some negative couplings mainly occurring of 2e site. The calculated results for the Sm₅Co₃₂Zr₂ cluster may lead to a better understanding of why SmCo_7-xZr_x is stable phase. Since the spin-up DOS peak of d electrons at E_F arises and the bonding of electrons at E_F strengthens with increasing Zr concentration, which results in the internal energy of the system decrease, the stable ferromagnetic order forms in SmCo_7-xZr_x.     

Synthesis of grafted poly(p‐phenyleneethynylene) with energy donor–acceptor architecture via atom transfer radical polymerization: Towards nonaggregating and hole‐facilitating light‐emitting material

In this contribution, we demonstrate a new effective methodology for constructing highly efficient and durable poly(p‐phenyleneethynylene) (PPE) containing emissive material with nonaggregating and hole‐facilitating properties through the introduction of hole‐transporting blocks into the PPE system as the grafting coils as well as building the energy donor–acceptor architecture between the grafting coils and the PPE backbone. Poly(2‐(carbazol‐9‐yl)ethyl methacrylate) (PCzEMA), herein, is chosen as the hole‐transporting blocks, and incorporated into the PPE system as the grafting coils via atom transfer radical polymerization. The chemical structure of the resultant copolymer, PPE‐g‐PCzEMA, was characterized by NMR and gel permeation chromatography, showing that the desirable copolymer was obtained with the narrow polydispersity. The increased thermal stability of PPE‐g‐PCzEMA was confirmed by thermogravimetric analysis and differential scanning calorimetry along with its macroinitiator. The optoelectronic properties of this copolymer were studied in detail by ultraviolet‐visible absorption, photoluminescence emission and excitation spectra, and cyclic voltammogram (CV). The results indicate that PPE‐g‐PCzEMA exhibits the solid‐state luminescent property dominated by individual lumophores, and also the energy transfer process from the PCzEMA blocks to the PPE backbone with a relatively higher energy transfer efficiency in the solid‐state compared to that of the solution state. Additionally, the hole‐injection property is greatly facilitated due to the presence of PCzEMA, as confirmed by CV profiles. All these data indicate that PPE‐g‐PCzEMA is a good candidate for use in optoelectronic devices. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3776–3787, 2007     

质子滴线区新的缓发质子先驱核121Ce

藉助核反应⁹²Mo(³²S ,3n)产生了未知的缓发质子先驱核¹²¹Ce ,并利用氦喷嘴快速带传输系统和“p-γ”符合方法对它进行了鉴别 .测定了¹²¹Ce的半衰期 ( 1.1±0 .1 )s,观测了它的β缓发质子能谱 ,粗略地估计了它的β缓发质子衰变道的分支比约为1% .首次观测了先驱核¹¹⁹Ba,¹²¹Ba和¹²²La经过β缓发衰变在“子核”中产生的低位能级到基态的γ 跃迁.     

狭义相对论效应──运动时钟变慢的计算机模拟演示实验

利用精炼的C语言进行程序设计，定量模拟狭义相结论的运动时钟变慢，并对处于两种不同时空观的时钟运行进行对比，使得时间膨胀效应变得直观。     

Synthesis and light emitting properties of polyacetylenes having pendent fluorene groups

Five novel fluorene‐containing polymers, poly[(9,9‐dimethylfluoren‐2‐yl)acetylene] ( PFA1 ), poly[(1‐pentyl‐2‐(9,9‐dimethylfluoren‐2‐yl)acetylene) ( PFA2 ), poly[1‐decyl‐2‐(9,9‐dimethylfluoren‐2‐yl)acetylene] ( PFA3 ), poly[1‐phenyl‐2‐(9,9‐dimethylfluoren‐2‐yl)acetylene] ( PFA4 ), and poly[1‐(3,4‐difluorophenyl)‐2‐(9,9‐dimethylfluoren‐2‐yl)acetylene] ( PFA5 ) were synthesized by the polymerization of the corresponding fluorene‐substituted acetylenic monomers ( M1–M5), using WCl₆, MoCl_5, and TaCl₅ as catalysts and n‐Bu₄Sn as a cocatalyst. The synthesized polymers were thermally stable and readily soluble in common organic solvents. The degradation temperatures for a 5% weight loss of the polymers were ∼352–503 °C under nitrogen. PFA1–PFA5 show emission peaks from 402 to 590 nm. Besides, their electroluminescent properties were studied in heterostructure light‐emitting diodes (LEDs), using PFA2–PFA5 as an emitting layer. The PFA5 device revealed an orange‐red emission peak at 602 nm with a maximum luminescence of 923 cd/m² at 8 V. A device with the ITO/PEDOT/ a mixture of PFA2 (98 wt %) and PFA5 (2 wt %)/Ca/Al showed near white emission. Its maximum luminance and current efficiency are 450 cd/m² at 15 V and 1.3 cd/A, respectively. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 519–531, 2006