幅相一致行波管高频电路CAD研究

 在行波管的设计和装配过程中，各部件的尺寸必须严格控制，高频电路参数的离散对行波管色散特性有极大的影响。使用螺旋导电面模型，模拟计算了高频结构各主要参数离散对色散特性和轴向互作用耦合阻抗的影响。分析计算了夹持杆宽度、翼片高度、螺旋线平均半径、螺距、夹持杆介电常数等离散时对色散特性和轴向互作用耦合阻抗的影响，为新型幅相一致行波管的设计和生产提供了很有价值的参考建议。     

横向射流式单重态氧发生器的性能实验研究

 对氧碘化学激光器的单重态氧发生器（SOG）进行了改进，采用横向射流方式，并对该横向射流式单重态氧发生器的性能进行了检测。实验中过氧化氢碱溶液温度控制在－16℃左右,氯气流量为530mmol/s，He与氯气的流量比为3;采用PS法测量单重态氧分子的产率,吸收法测量氯气的利用率和相对水含量。得出如下结论:在不使用冷阱和分离器的情况下，最高单重态氧分子产率达到58%, 氯气利用率在80%以上,相对水含量小于等于0.5;气体达到最大流量时,发生器仍然能稳定地工作。     

与q形变玻色算符逆算符相关的相干态及其量子统计性质

讨论了ｑ形变玻色算符的广义逆算符作用于ｑ－相干态所得到的两类量子态的数学及量子统计性质。结果表明，ｑ－相干态的光子激发态不存在压缩但呈现反聚束效应，而ｑ－相干态的光子湮灭态却存在压缩但不呈现反聚束效应。     

饱和恢复法人体核磁共振自旋—晶格弛豫时间成象方法

当前,在医学核磁共振成象领域内,临床上广泛采用的是近似的自旋密度象、T1-和T2-加权密度象。但是,由于人体的正常组织和肿瘤之间的密度差别不大,从质子密度象很难区分人体的正常组织与肿瘤,而肿瘤与人体正常组织之间的在弛豫时间T1、T2的数值上差别较大。另外,自七十年代以来,大量关于离体(in vitro)核磁共振弛豫时间测量的文献表明,肿瘤的核磁共振弛豫时间T1,T2值具有明显的规律性,从而利用核磁共振弛豫时间成象的方法,及人体正常组织、良性及恶性肿瘤的活体(in vivo)T1,T2数值的测量,将有助于实现肿瘤识别的定量方法。     

Intravascular and Intracellular Hepatic Relaxivities of Superparamagnetic Particles: An Isolated and Perfused Organ Pharmacokinetics Study

The relative contributions of intravascular and intracellular compartments to the proton transverse relaxation of the isolated and excised rat liver were determined during the phagocytosis of superparamagnetic particles. The evolution of the proton transverse magnetization of the organ perfused with increasing doses of starch-coated magnetic microspheres was followed up using a Carr–Purcell–Meiboom–Gill sequence with various echo times. From the multiexponential fit of the echo train, the amplitudes and the relaxation ratesR₂of the liver tissue were obtained. The results clearly indicate that shortly after contrast medium administration, an internalization takes place which can be followed by the rapid and biphasic evolution of the transverse relaxation rate of the water protons. A very fast decaying component looking like an initial loss of the magnetization is observed together with an increase of the relaxation rate of the remaining water tissue. This regime is strongly dependent on both the echo time and the iron concentration, a behavior characteristic of the agglomeration of magnetic particles. The examination of the liver tissues by electron microscopy shows that this clustering arises in cytoplasmic vacuoles.     

Accelerated Hydrolysis of p-Nitrophenyl Picolinate Catalyzed by Metallomicelle Made from a Novel Macrocyclic Polyamine Copper（Ⅱ） Complex

A copper（Ⅱ） complex 1 of a novel macrocyclic polyamine ligand with hydroxylethyl pendant groups, 4,11-bis（hydroxylethyl）-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane （L） has been synthesized and characterized. Rate enhancement for hydrolysis of p-nitrophenyl picolinate （PNPP） catalyzed by 1 was studied kinetically under Brij35 micellar condition. For comparision, the catalytic activity of corresponding copper（Ⅱ） complex 2 of non-substituted macrocyclic polyamine ligand, 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraaza-cyclotetradecane （L＇） toward the hydrolysis of PNPP was also investigated. The results indicate that the macrocyclic polyamine copper（Ⅱ） complex 1 effectively catalyzed the hydrolysis of PNPP, and the pendant ligand hydroxyl group or deprotonated pendant ligand hydroxyl group can act as catalytically active species in the reaction. A ternary Complex kinetic model involving metal ion, ligand and substrate has been proposed, and the results confirmed the reasonability of such kinetic model.     

Characterization of CNS disorders and evaluation of therapy using structural and functional MRI

Modern drug development requires technologies that allow rapid translation from the preclinical to the clinical stage. It is obvious that non-invasive imaging modalities such as magnetic resonance imaging (MRI) will play a central role in this regard. This article reviews the use of structural and functional MRI readouts for characterization of central nervous system (CNS) disorders and evaluation of the efficacy of potential CNS drugs. Examples comprise dementia of Alzheimer's type, cerebral ischemia, and neuroinflammation covering both clinical and preclinical aspects. In these examples MRI has been used to obtain relevant structural information on brain atrophy, on the location and extent of ischemic brain areas, and on the number and distribution of demyelinated plaques. These structural data are complemented by readouts assessing the functional consequences associated with the pathomorphological changes. In the last decade, MRI has evolved into a standard tool for the development of CNS drugs. With regard to target-specific/molecular imaging applications MRI is limited by its inherently low sensitivity; complementary imaging modalities utilizing optical and radionuclear reporter systems will thus be required.     

聚4-重氮基苯乙烯与聚苯乙烯磺酸钠的自组装

1991年Ｄｅｃｈｅｒ等将带相反电荷的聚电解质 ,于水溶液中交替沉积在片基上 ,制备了多层超薄膜[1] ,这种制膜方法现称为静电自组装 .它操作简单 ,无需专用设备 ;一般在水体系进行 ,对环境友好 ;静电力比范德华力强 ,使它比ＬＢ膜稳定 ,所以近年来有很大发展[2 ] .现在自组装成膜驱动力已从静电力扩展到氢键力、电荷转移相互作用、疏水相互作用等 ,用于组装的组分也从聚电解质扩展到多官能团小分子、胶体粒子、无机纳米颗粒 ,ＤＮＡ、蛋白质等生物大分子等[3～ 11] .虽然自组装膜比ＬＢ膜稳定 ,但它也不耐极性溶剂、电解质水溶液等侵蚀 .如…     

Synthesis of N-（α-Alkoxyalkyl）benzotriazoles Catalyzed by Acidic Ionic Liquid at Room Temperature

N-（α-Alkoxyalkyl）benzotriazoles were synthesized via the condensation of benzotriazole with various aldehydes and alcohols catalyzed by acidic ionic liquid [hmim]HSO4 at room temperature. The yield was up to 99%. This novel method was effective when triethoxymethane was utilized instead of alcohols. Moreover, acidic ionic liquid could be reused easily with no significant degradation of its catalytic activity.     

An Environmentally Benign System for Synthesis of β-Hydroxylketones： L-Histidine Asymmetrically Catalyzed Direct Aldol Reactions in Aqueous Micelle and Water-like Media

The first histidine catalyzed direct aldol reactions of ketones with nitrobenzaldehydes in water and in poly（ethylene glycol） （PEG） were reported. It reveals that histidine is a good aldol catalyst for synthesis of β-hydroxylketones in water and in PEG, giving good to excellent yields of the respective products. Better enantioand regioselectivity were achieved using low molecular weight PEG as the media. The results show that histidine and PEG-200 or -300 may constitute a promising environmentally benign system for asymmetric synthesis of β-hydroxylketones.