快扫相关核磁共振技术在上海通过了鉴定

华东师范大学物理系波谱学教研室自80年以来,结合研究生教学和课题,对快扫相关核磁共振(RSNMR)技术开展了研究,于84年10月通过了鉴定。RSNMR技术是利用核磁共振的快扫响应信号(即摆动尾波)与参考信号作互相关处理得到NMR谱的。自己设计研制了计算机控制扫描部分、数据采集部分以及控制显示部分,用汇编语言编写了六条BASIC语言     

扫场对核磁共振测量的影响

在连续波核磁共振实验中，通常采用低频扫场产生重复再现的共振吸收信号。当处于磁场中的射频线圈引线回路等效面积不为零时，简谐扫场必然引起该闭合回路的磁通量变化，由此而产生同频简谐感生电动势并与核磁共振信号叠加共同构成振荡器输出信号。由于扫场上升和下降过程的感生电动势方向相反，从而扫场前半周和后半周所对应的共振吸收测量信号存在差异。实验结果表明：扫场强度及方向对核磁共振测量影响来源于实验测量技术缺陷，而非核磁共振的物理本质。     

双傅氏变换核磁共振波谱学

二维NMR波谱是近十年来核磁共振领域内的重要新发展之一。本文综述了实现二维谱的五种可能性。给出双傅氏变换核磁共振谱的基本原理及实验的一般方法。讨论了这类谱的两个主要分支即:二维分谱解及二维相关谱。     

双傅氏变换核磁共振波谱学

二维NMR波谱是近十年来核磁共振领域内的重要新发展之一。本文综述了实现二维谱的五种可能性。给出双傅氏变换核磁共振谱的基本原理及实验的一般方法。讨论了这类谱的两个主要分支即:二维分谱解及二维相关谱。     

核磁共振一维同类核相关编辑

本文用自旋密度算符理论分析了“硬”脉冲回波序列所得到的一维核磁共振同类核相关编辑问题。提出的实验方法与理论分析预期一致,并证明这种同核相关编辑的结果与二维核磁共振COSY谱所揭示的相关关系一致,但是一维相关编辑具有省时,节约内存和保留一维谱的灵敏度和分辨率以及保留谱的精细结构等优点。 关键词：     

核磁共振发现50周年

核磁共振在当前有着广泛和重要的应用，文中简明扼要地介绍了核磁共振发现的历史背景和经过，以及相关磁共振的发现，指出了核磁共振的特点、主要进展和多方面的应用，阐述了从核磁共振谱发展到核磁共振成像的重要意义及这种成像的特点；最后对核磁共振的发展作了若干展望。     

一种基于组分补偿的二维核磁共振测井数据高精度处理方法

二维核磁共振技术能够对储层中各类含氢流体进行无损、快速、定量的测量和表征，但受限于采集方式和参数，核磁共振设备在对页岩油等致密储层中的有机质、沥青等超快弛豫组分进行检测时，经常出现由于信号采集不完整所导致的二维谱中流体组分缺失或不准的问题.本文提出了基于超快弛豫组分补偿技术的T₂-T₁二维谱高精度反演方法，该方法将一维核磁共振前端信号补偿技术进行推广，通过在二维核磁数据反演前对回波数据进行组分补偿，能够有效解决二维核磁共振测井前端信号漏失的问题.实验及测井数据的应用表明，该方法在页岩油等富含快弛豫组分信号的储层中，可以得到更加精准和完整的储层信息.     

蛋白质分子核磁共振谱峰的特性及其化学位移归属

尽可能完全、准确地归属蛋白质分子的核磁共振（Nuclear Magnetic Resonance,NMR）谱峰,是解析可信赖、高质量的蛋白质三维空间溶液结构的首要条件．自动归属软件的开发和应用,已经方便并加快了蛋白质分子核磁共振谱峰的归属进程．然而,对蛋白质核磁共振研究领域的新手来说,因为缺乏对蛋白质分子的核磁共振谱峰特性的系统认识而可能发生对自动归属结果的错误指认或指认不完全,从而导致蛋白质结构解析的错误或偏差．该文针对蛋白质分子中的核磁共振谱峰特性,比如同位素效应和立体异构等,结合具体的蛋白质分子的核磁共振实验图谱,进行了较为详尽的论述,期望对从事蛋白质核磁共振的研究者在理解蛋白质分子的核磁共振谱峰特性及其归属方面有所裨益．     

绣线菊碱Ⅲ的结构研究

利用核磁共振谱对绣线菊碱Ⅲ(Spirasine Ⅲ)结构中的碳,氢信号作了归属,用同核相关谱和异核相关谱分析了噁唑烷环存在带来的双信号问题,指认出C_1,R,S两种构型的信号并对噁唑烷环的ABXY体系做了模拟。     

一种核磁共振波谱谱峰对齐及谱峰提取的方法

在代谢组学研究方法中,对一组具有生物学意义且平行的核磁共振波谱数据进行处理是其方法研究的关键,其中包含谱峰对齐、谱峰提取、噪音去除等几个步骤。该文提出了一种全新且快速有效的核磁共振波谱批量处理方法。其原理主要为：在保持波谱形状不发生变化的同时,通过平移目标谱使其与参考谱达到最大程度的相关,从而实现谱峰对齐及利用谱峰最大值的判断来实现谱峰变量的提取。此外,该文还结合大鼠尿样和血样的分析结果,详细地说明了算法的准确性及其它优点。该文所涉及的算法是基于Matlab程序进行编译的,可以结合不同实验进行改编,具有良好的扩展性。     

Vapour and plasma ignition thresholds for visible pulsed-laser ablation of metallic targets

The coupling of visible nanosecond laser pulses to metallic targets irradiated in vacuum is studied. The expressions of the vapour and plasma ignition times are obtained. Two cases for vapour breakdown in the plasma ignition process are considered. The first case is that 40 generations of new electrons are born in vapour generation time before plasma formation as assumed in the literature. The second case is that 10 generations of new electrons are born in vapour generation time. Molybdenum (Mo), niobium (Nb) and aluminium (Al) targets are considered for illustrations of our results. The expression of the plasma ignition time for the Al target is substantially different from that reported in the literature. The vapour and plasma ignition threshold laser intensities are calculated and compared with those reported in the literature. Reasons for disagreement are discussed. The plasma ignition threshold estimated in the second case is noted to be in good agreement with the reported experimental result.     

Equivalent circuits and directivity patterns of air-coupled ultrasonic transducers

Air-coupled transducers for producing ultrasonic radiation in gases are studied. The transducer consists of a circular thin plate in flexural vibration and a sandwich longitudinal electromechanical vibrator that is attached to the center of the plate. The lowest-order axially symmetric flexural vibrational mode of a circular thin plate is analyzed. The equivalent circuits of the circular plate in flexural vibration and the compound transducer are presented and the frequency equation is derived. The radiated ultrasonic field of the circular thin plate in flexural vibration is calculated and the directivity pattern is obtained theoretically. Some transducers of this type are designed according to the frequency equation, and their resonance frequencies are measured. The measured resonance frequencies are in good agreement with the theoretical results, and the calculated radiation ultrasonic field is also in good agreement with the measured results of a previous work.     

大口径光学平面的子孔径拼接检验研究

研究了检测大口径光学平面的子孔径拼接法。通过采用最小二乘法对相邻两个子孔径重叠区域的数据进行分析,获得了子孔径之间的拼接参量,得到了被检验镜面的整体面形信息。编制了拼接检验的计算程序,并完成了原理性实验。采用一台口径为100mm的移相干涉仪检测了两个样品,给出了拼接检测与全口径检测的对比结果。样品的口径分别为100mm和91mm。对比检测结果表明,拼接检测与直接检测两种方法的RMS之差小于5nm。     

Quantum theory of stimulated raman scattering in an inhomogeneously broadened three-level gaseous system

A quantum-statistical treatment of stimulated Raman scattering in a gaseous system is presented using a density-matrix formalism. The molecular (atomic) system is described by three energy levels. Both atomic system and the radiation fields are quantized. The effects of atomic motion and detuning are incorporated in the analysis. Higher order nonlinearities and loss terms are included to render the problem more realistic. The equations of motion describing the photonstatistics of pump and Stokes fields are obtained. The equation, without detailed balance, is solved in the steady-state by a slowly varying function technique in the case of two variables. The steady state characteristics of the Stokes field are studied. The coherence properties, occurrence of antibunching phenomena are studied for different initial distributions.     

Anomalies of radiation absorption and superluminal propagation of light: I. An isotropic layer

The features of superluminal propagation of light through an isotropic layer are investigated and the group velocity is calculated. Multilayer systems providing superluminal propagation of light over large distances with compensation of losses upon light transmission through the system are considered. The situations in which the propagation speed of a light pulse decreases or in which it is equal to zero are also investigated. The features of radiation absorption in a thin isotropic layer are considered. The effects of anomalously high and anomalously low absorption are found. It is shown that these effects are caused by an increase (decrease) in the density of light energy in the layer and by changes in the group velocity. The possibility of experimental observation of the effects discovered is discussed.     

基于偏振成像技术的目标探测研究进展及分析

简述了利用偏振成像技术进行目标探测的物理特性,介绍了偏振成像技术的应用优点,概括分析了我国利用偏振成像技术进行目标探测的发展状况,指出了发展中存在的问题,叙述了国外在该研究方向所取得的主要成就。总结分析了基于偏振成像技术的目标探测的研究进展,并对其未来发展方向进行了展望。     

Nonlinear free vibrations of beams in space due to internal resonance

The geometrically nonlinear free vibrations of beams with rectangular cross section are investigated using a p-version finite element method. The beams may vibrate in space, hence they may experience longitudinal, torsional and non-planar bending deformations. The model is based on Timoshenko’s theory for bending and assumes that, under torsion, the cross section rotates as a rigid body and is free to warp in the longitudinal direction, as in Saint-Venant’s theory. The geometrical nonlinearity is taken into account by considering Green’s nonlinear strain tensor. Isotropic and elastic beams are investigated and generalised Hooke’s law is used. The equation of motion is derived by the principle of virtual work. Mostly clamped–clamped beams are investigated, although other boundary conditions are considered for validation purposes. Employing the harmonic balance method, the differential equations of motion are converted into a nonlinear algebraic form and then solved by a continuation method. One constant term, odd and even harmonics are assumed in the Fourier series and convergence with the number of harmonics is analysed. The variation of the amplitude of vibration with the frequency of vibration is determined and presented in the form of backbone curves. Coupling between modes is investigated, internal resonances are found and the ensuing multimodal oscillations are described. Some of the couplings discovered lead from planar oscillations to oscillations in the three dimensional space.     

Vibrations of a textile machine rotor

In this paper the vibrations of a textile machine rotor, whose angular velocity is constant, are analyzed. The function of the rotor is to wind up a band of textile material into a roll. The elastic force in the shaft is assumed to be non-linear. First the free vibrations of this rotor are analyzed analytically and numerically. The results are compared. After that the vibrations in the non-resonant case are analyzed. The solution is found by use of the analytical method of multiple scales. The results for free vibrations and for the non-resonant case are compared.     

An axiomatic scheme more general than quantum theory

An axiomatic scheme generalizing the operational approach to quantum theory is described. Only quite general axioms ensuring the existence of well-behaved probabilities are postulated. The space-time location of macroscopic apparatus interacting with the object is explicitly taken into consideration. The states and observables are defined and their time development is considered. The classification of physical processes with respect to their reversibility or irreversibility in time is given. The conditions of Lorentz and translational invariance are formulated. Linear transformations corresponding to operations on the object are introduced. In the case of reversible processes these transformations form an algebra and linear representations of the Poincaré group arise naturally. These results are, in general, invalid for irreversible processes. The position of quantum theory in the scheme described is clarified.