压力法测量保偏光纤拍长参数的系统分析

本文从实际工作出发，系统全面地分析总结了压力法测量保偏光纤拍长的原理和方法，给出了单模工作情况下侧向压力作用模式耦合的严格理论分析．从理论和实验两方面分析证实了出／入光线偏振角度与测量结果的关系，并进一步给出了多模工作情况下的理论分析和实验结果．     

固氮鱼腥藻(Anabaena azotica Ley HB686)氮固定的能量和还原剂来源

某些外源碳水化合物提高固氮鱼腥藻的固氮能力.在光照和5%氧浓度条件下,分子氢促进固氮作用.光合抑制剂、呼吸链抑制剂和解偶联剂均抑制固氮酶活性,若同时加入葡萄糖,DCMU的抑制作用被解除,而对DBMIB和解偶联剂的作用影响甚微.固氮鱼腥藻固氮作用的还原剂与光合作用产生的碳化合物有关,能量主要由循环光合磷酸化供给.     

Design of single chain magnets through cyanide-bearing six-coordinate complexes

The design and preparation of stable cyanide-bearing six-coordinate complexes of formula [M^III(L)(CN)_x]^{(x + l − m)−} (M = trivalent transition metal ion and L = polydentate blocking ligand) are summarized here. Their use as ligands towards either fully hydrated metal ions or coordinatively unsaturated preformed species, to afford a wide variety of low-dimensional metal assemblies whose nuclearity, dimensionality and magnetic properties can be tuned, is also reviewed. Special emphasis is put on the appropriate choice of the end-cap ligand L whose denticity determines the number of coordinated cyanide groups in the mononuclear precursors. Among the different new spin topologies obtained through this rational synthetic strategy, ferromagnetically coupled 4,2-ribbon like bimetallic chains which exhibit slow magnetic relaxation and hysteresis effects (chain as magnets) are one of the most appealing and constitute the heart of the present contribution.     

非石油基高分子材料聚羟基脂肪酸酯PHA的改性研究进展

综述了近年来国内外在新型生物可降解材料聚羟基脂肪酸酯(Polyhydroxyalkanoates,PHA)家族主要代表:聚羟基丁酸酯(PHB)、聚3-羟基丁酸酯-co-3-羟基戊酸酯的共聚物(PHBV),聚3-羟基丁酸酯-co-4-羟基丁酸酯的共聚物(P3/4HB)和聚3-羟基丁酸酯-co-3-羟基己酸酯的共聚物(PHBHHx)的生物、化学和物理三种改性和加工方面的研究进展。通过生物方法可以使PHA材料的化学结构、组成、机械力学性能和成型加工性能更具有多样性和可调性;通过化学途径可以使PHA材料的功能性进一步突出和增强,例如可以使PHA为基础的材料具有优异的生物医学性能,同时也具有好的加工性能;利用物理共混和反应性挤出使PHA材料的所有性能缺陷得到进一步修补,使其更具有实用价值。近十年来,通过以上这些改性手段的结合,PHA力学性能不均衡和成型加工的难题得到了解决,使PHA生物聚酯这类新型非石油基高分子材料得到了飞速发展,其综合性能甚至价格具备了代替部分石油基高分子材料的可能,PHA生物聚酯的规模化工业制造和应用的时代已经来临。     

HB9X9˙ and H2B9X9 (X = Cl,Br, I): Neutral closo-Nonaboranes in the Novel Series BnHn+1, and BnHn+2 – Syntheses,Ab Initio Calculations,and Electronic Structures

Chemical reduction of B₉X₉ (X = Cl, Br, I) with gaseous HI proceeds stepwise to give the neutral paramagnetic clusters HB₉X₉ ^· , and the corresponding diamagnetic clusters H₂B₉X₉. Together they comprise the first neutral derivatives in the series B_nH_n+1 and B_nH_n+2 with n = 9. The EPR spectra of the paramagnetic HB₉X₉ ^· (X = Cl, Br, I) in glassy frozen CH₂Cl₂ solutions showed increasing g anisotropy for the heavier halogen derivatives, illustrating significant halogen participation at the singly occupied MO due to the larger spin-orbit coupling contributions. Temperature dependent ¹H NMR spectra of H₂B₉X₉ (in CD₃CN, X = Cl, Br) indicate the presence of H₂B₉X₉, [HB₉X₉]^–, and [CD₃CNH]⁺ with H₂B₉X₉ acting as a Brønsted acid. The corresponding ¹¹B NMR spectra (in CD₃CN) show the presence of the dianions [B₉X₉]^2– as a result of the protonation of CD₃CN. The ¹¹B resonances of the species H₂B₉X₉ and [HB₉X₉]^– are obscured by superimposition of the two resonance lines of the dianions [B₉X₉]^2–. Temperature dependent ¹¹B{¹H} MAS-NMR spectra of H₂B₉Br₉ show coalescence at 410 K and hence dynamic behaviour of the neutral B₉-cluster in the solid. Cyclic voltammetry experiments of H₂B₉Br₉ in CH₃CN solvent) are compatible with the redox sequence [B₉Br₉]^2––[B₉Br₉] ^{· –}–B₉Br₉. Quantum chemical calculations with the electron localization function (ELF) are described.     

Molecular Tailoring Approach for the Estimation of Intramolecular Hydrogen Bond Energy

Hydrogen bonds (HBs) play a crucial role in many physicochemical and biological processes. Theoretical methods can reliably estimate the intermolecular HB energies. However, the methods for the quantification of intramolecular HB (IHB) energy available in the literature are mostly empirical or indirect and limited only to evaluating the energy of a single HB. During the past decade, the authors have developed a direct procedure for the IHB energy estimation based on the molecular tailoring approach (MTA), a fragmentation method. This MTA-based method can yield a reliable estimate of individual IHB energy in a system containing multiple H-bonds. After explaining and illustrating the methodology of MTA, we present its use for the IHB energy estimation in molecules and clusters. We also discuss the use of this method by other researchers as a standard, state-of-the-art method for estimating IHB energy as well as those of other noncovalent interactions.     

The Lie Algebras in which Every Subspace Is Its Subalgebra

In this paper, we study the Lie algebras in which every subspace is its subalgebra （denoted by HB Lie algebras）. We get that a nonabelian Lie algebra is an HB Lie algebra if and only if it is isomorphic to g＋Cidg, where g is an abelian Lie algebra. Moreover we show that the derivation algebra and the holomorph of a nonabelian HB Lie algebra are complete.     

多速率信号处理的设计与实现

多速率信号处理是软件无线电的理论基础,该文介绍了一种高效的多速率信号处理方法,即采用CIC滤波器、HB滤波器、FIR滤波器和多相滤波器等实现抽取和内插以达到改变信号速率的目的。文中介绍了各种滤波器的基本原理,分析了设计实现时需要注意的问题,并给出了采用这种多速率信号处理方法实现数字下变频的设计结果。