WATR法测量稀水溶液的1H-NMR谱

本文讨论了用WATR法消除稀水溶液中的水共振峰,进行¹H-NMR谱测定的原理、影响T₂的因素及应用实例。WATR法是在水溶液中加入氯化胺、盐酸羟胺和盐酸胍等水质子交换试剂以降低水质子的T₂,然后用CPMG脉冲系列来测定¹H-NMB谱。本法最适用于稀水溶液中处于水共振峰内或附近的样品的共振峰的测定,还可测定稀水溶液中¹⁵N-¹H的化学位移及耦合常数,到目前为止尚未见有这方面的报导。     

筋骨草甾酮C的谱学特征

筋骨草甾酮C是分布于植物中的植物甾酮类化合物,具有抗氧化的作用.本文标定了该化合物中所有的碳信号,并通过¹³C-¹H COSY和¹H-¹H COSY技术纠正了文献中氢信号归属的错误.     

二维接力-HOHAHA和NOE差谱法测定甙类化合物的结构

该文提出一种新的二维接力-HOHAHA实验方法.研究结果表明,该方法可用于从高度重迭的谱图中分离出各个糖体的¹H NMR信号,并且与NOE差谱实验相结合可以用于测定甙类化合物中糖体间和糖体与甙元间的连接位置.本方法以¹H NMR为基础,故其灵敏度比以¹³C NMR为基础的甙化位移方法高得多.     

MRI定域二维谱

定域谱和二维谱技术都是NMR的重要研究手段.定域二维谱,就是将二者结合,同时具有空间信息和二维谱的诸多优点.本文利用STEAM脉冲序列加以改造,完成了三维空间定域的二维¹H-¹H NOESY实验.     

自旋回波付里叶变换核磁共振波谱法识别13C谱

¹³C自旋回波付里叶变换(SEFT)序列脉冲技术与¹H去偶技术配合能够简化¹³C谱,便于识别C、CH、CH₂、CH₃谱线。本文介绍了用FT-80A NMR谱仪应用其中两种脉冲序列的实验条件并将几种纯烃化合物和混合芳烃样品的实验结果与常用实验技术进行了比较和讨论。     

卡泊三醇的核磁共振谱解析

利用核磁共振氢谱（¹H NMR）、碳谱（¹³C NMR）、同核位移相关谱（¹H-¹H COSY）、异核单量子相干谱（HSQC）和异核多键相关谱（HMBC）等多种核磁研究方法对抗银屑病药物卡泊三醇的¹H、¹³C信号进行完全归属.     

1-甲基环氧乙烷-1-丙炔醚的结构测定及其核磁图谱

以¹H-NMR谱和¹³C双自旋回波的APT脉冲序列测定文献中尚未曾发表的化合物HC≡C-CH₂-O-C^CH₃-_O-CH₂文中计算了峰强度与脉冲间隔时间的关系,讨论了各谱线的相位并区分出-CH₃、-CH₂、-CH和季碳。     

固体中13C CP/MAS谱编辑一些改进

本文将基本的谱编辑脉冲序列与消旋转边带的TOSS脉冲序列联用,可以实现强磁场下¹³C CP/MAS谱编辑.通常,固体中非质子化碳与甲基碳的自旋晶格弛豫时间差别很大,此差别可作为谱编辑过程中区分它们的一条附加判据.对具有复杂分子结构的体系,此判据的作用尤其重要.文中的实例将表明:一个完整的¹³C CP/MAS谱编辑一般可通过SCPTOSS谱(短接触时间交叉极化谱);SCPPITOSS (短接触时间交叉极化极化反转)谱,LCPDTOSS (长接触时间交叉极化及去极化)谱及部分弛豫的LCPDTOSS谱适当组合而得到.     

罗汉果甙V的核磁共振谱研究

用一维¹H、¹³CNNMR,二维¹H-¹H COSY、¹³C-¹H COSY和NOE差谱技术研究了从鲜罗汉果中分离出一种含5个葡萄糖的三萜甙、罗汉果甙V,确定了其甙元与糖基、糖基与糖基之间的连接方式,并首次对其¹H和¹³C NMR谱中的全部信号进行了归属。     

系列Mo-Cu(Ag,Au)-Se簇合物的95Mo和31P NMR研究

报道了含硬币金属和四硒代钼酸盐的异金属硒簇合物的⁹⁵Mo NMR研究结果和含膦配体Mo(W)-Cu(Ag,Au)-Se配合物的³¹P NMR谱学性能。发现不同硬币金属对⁹⁵Mo核的化学屏蔽效应顺序为Au > Cu > Ag;对系列Mo-Cu-Se化合物的⁹⁵Mo NMR研究结果表明:⁹⁵Mo NMR的化学位移和线宽不仅与配位的Cu原子数目有关,而且对结构的变化特别敏感;[MoSe₄]^2-离子的相对四个方向被Cu⁺配位后,其Mo核的屏蔽基本饱和;外围配体对⁹⁵Mo NMR数据影响甚微。同时还用动态⁹⁵Mo NMR谱技术跟踪配体的取代反应和从MoCu₄到MoCu₁₀核的簇骼转变过程。此外,还讨论了这些化合物在不同构型之间,同一构型不同金属中心和不同配体基团的³¹P NMR化学位移的变化特征。     

冲击波加载下PZT95/5铁电陶瓷电响应的数值模拟

 在爆炸冲击波垂直加载下,考虑了介质的松弛现象及其有限电导率,建立了PZT95/5铁电陶瓷电响应的数学模型。利用这一模型,分析了PZT95/5在短路、电阻、电容和电感等各种负载下的电响应。理论模型与实验结果较好地符合。     

Ansatz’95

Abstract

In this talk I am going to present a brief review of some key ideas and methods which were given start and were developed in Kyiv, at the Institute of Mathematics of National Academy of Sciences of Ukraine during recent years.     

Der Zerfall des95Sr

The nuclide⁹⁵Sr was isolated by chemical separation methods after thermal neutron induced fission of²³⁵U. It's decay properties were investigated employing semiconductor spectrometers and coincidence techniques. A half-life of 24.4±0.2 sec was found. Out of 29 gamma rays, 25 transitions representing 97% of the observed gamma-ray intensity were placed in a decay scheme comprising 19 excited states of⁹⁵Y.     

PZT－95／5压电陶瓷的冲击波活化改性研究

研究了冲击波对ＰＺＴ－９５／５压电陶瓷的活化改性作用，对ＰＺＴ－９５／５粉末及块状材料进行动态冲击波加载。实验表明：在合适的条件下，冲击波作用可提高样品的密度ρ，压电应变常数ｄ３３，介电常数ε，降低介电耗损系数ｔｇδ％。通过对样品进行Ｘ射线衍射，扫描电镜ＳＥＭ、透射电镜ＴＥＭ和Ｘ射线光电子能谱ＸＰＳ等微观测试分析，揭示了冲击波改性的机理主要是：晶粒细化，晶界破坏，孔隙增多，缺陷增多，相变产生等，从而达到对样品改性的作用     

冲击波压缩PZT-95/5铁电陶瓷的电介质击穿

 应用冲击波加载技术，在垂直加载的条件下，研究了PZT-95/5铁电功能陶瓷的电击穿。通过实验和数值模拟，得到了冲击波加载下的动态击穿特征参数，讨论了其击穿机理。     

Accurate determination of the half-lives of95Zr and95Nb

The half-lives of⁹⁵Zr and⁹⁵Nb have been determined byγ-ray counting using a Ge(Li) detector and a NaI(Tl) crystal. Data have been recorded at regular time intervals during time periods up to nine times the respective half-life. The obtained results are T_1/2(⁹⁵Zr)= (64.05±0.06) days and T_1/2(⁹⁵Nb)=(34.97±0.03) days. A detailed discussion of the measurements and the uncertainty assignment is given.     

氢对非晶态Y5Ni95合金膜的磁性和电子输运性质的影响

采用电解法实现了非晶态Y,Ni₉₅合金的加氢。在1.5—400K温度范围内测量了a-Y,Ni₉₅H_x(x=0—15.1)合金的磁矩、电阻率和霍耳电阻率随氢含量的变化关系。结果指出,随氢含量增加,样品的0K磁矩、居里温度和电阻率温度系数显著下降,而高场磁化率、电阻率和反常霍耳系数则迅速增加。借助现行的理论对加氢引起的上述影响进行了简要的讨论。 关键词：     

Two-dimensional pulsed TRIPLE at 95 GHz

The one-dimensional (1D) pulsed TRIPLE resonance experiment, introduced by Mehring et al. (M. Mehring, P. Hofer, and A. Grupp, Ber. Bunseges. Phys. Chem. 91, 1132-1137 (1987)) is a modification of the standard Davies ENDOR experiment where an additional RF pi-pulse is applied during the mixing time. While the first RF pulse is set to one of the ENDOR transitions, the frequency of the second RF pulse is scanned to generate the TRIPLE spectrum. The difference between this spectrum and the ENDOR spectrum yields the difference TRIPLE spectrum, which exhibits only ENDOR lines that belong to the same M(S) manifold as the one selected by the first RF pulse. We have extended this experiment in two dimensions (2D) by sweeping the frequencies of both RF pulses. This experiment is particularly useful when the spectrum is congested and consists of signals originating from different paramagnetic centers. The connectivities between the peaks in the 2D spectrum enable a straightforward assignment of the signals to their respective centers and M(S) manifolds, thus providing the relative signs of hyperfine couplings. Carrying out the experiment at high fields has the additional advantage that nuclei with different nuclear gyromagnetic ratios are well separated. This is particularly true for protons which appear at significantly higher frequencies than other nuclei. The feasibility and effectiveness of the experiment is demonstrated at W-band (94.9 GHz) on a crystal of Cu(2+)-doped l-histidine. Homonuclear (1)H-(1)H, (14)N/(35)Cl-(14)N/(35)Cl and heteronuclear (1)H-(14)N/(35)Cl 2D TRIPLE spectra were measured and from the various connectivities in the 2D map the (1)H, (14)N, and (35)Cl signals that belong to two different Cu(2+) centers were identified and grouped according to their M(S) manifolds. Copyright 2000 Academic Press.     

Index to volume 95

The linear and non-linear (large amplitude), axisymmetric free vibration of a circular plate of variable thickness, with immovable edges, is analyzed by applying the transfer matrix method. Two types of circular plate are studied: the stepped thickness plate and the continuously variable thickness plate. Numerical calculations are carried out for these two types of plate, with both simply supported and clamped edges, and the backbone curves and mode shapes are determined. The results are compared with those of other authors.     

Die γ-Spektren von Tc95, Tc95m und Tc96

Theγ spectra of Tc⁹⁵ (20 h), Tc^95m (62 d), and Tc⁹⁶ (4.3 d) have been investigated using Li-drifted germanium counters. The observedγ transitions in the decay of Tc⁹⁵ and Tc^95m are in agreement with earlier investigations except for 6 transitions at 204, 680, and 840 keV in Tc⁹⁵ and at 970, 1390, and 1630 keV in Tc^95m reported previously which have not been confirmed. In the spectrum of Tc⁹⁶ new transitions at 437, 462, 1094, 1200, and 1505 keV have been identified. The level scheme of Mo⁹⁶ is discussed in respect of these results.