摘要:

AbstractAn inaccurate description of magnetic resonance is current among those employing it in medicine and biology. The technique is purported to use radio waves for both stimulation of the sample and for reception of the ensuing signal. Arguments are presented which counter this myth, and using only magnetic fields, an accurate classical description of transmission and reception is given.

ISSN:1043-7347    

DOI:10.1002/cmr.1820010104

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractA two‐dimensional (2D) NMR spectrum is produced from the double Fourier Transform (FT) of two time domains,t1andt2. One of these domains,t2, is identical to the acquisition time used to collect a Free Induction Decay (FID) in one‐dimensional (1D) NMR spectroscopy. After performing the FTs of a series of these FIDs, an array of resonance lines is obtained whose amplitudes and phases are a function oft1. Thet1domain is then composed of another series of “FIDs” that are related to those collected duringt2. In this article, it is shown that in a heteronuclear‐J, δ gated‐decoupling experiment, the “FIDs” in thet1domain produce, after the FT, proton‐coupled spectra whose sum is identical to that obtained from a 1D carbon FID collected with no

ISSN:1043-7347    

DOI:10.1002/cmr.1820010105

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe heart has been one of the most extensively studied biological tissues using NMR spectroscopy. The importance of the heart function and the prevalence of heart disease are major reasons for this attention. However, several aspects of the heart's morphology and the availability ofin vitromodels suitable for NMR studies have also been important factors in the application of this technique. The purpose of this discourse is to review the techniques used to perform the NMR spectroscopy experiment on the heart, bothin vitroandin vivo.

ISSN:1043-7347    

DOI:10.1002/cmr.1820010106

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe most common experiment for determiningT1is the inversion‐recovery sequence: 180° ‐ τ −90°‐acquire. The advantage is a large range of peak intensity change (theoretically −1 to +1), and the penalty is the requirement for collecting many long‐τ spectra to establish precisely the equilibrium magnetization value,M(∞). A modification of inversion‐recovery: 180° ‐ τ −90° ‐acquire (+) ‐ wait −90° ‐ acquire(−) ‐ wait, offers the same range of intensity change (2 to 0) but relaxes the requirement for many long‐τ spectra, sinceM(∞) = 0. A more fundamental advantage is a reduction in the number of adjustable parameters in the fit, thereby making the detection and analysis of nonexponential relaxation more straightforward than for traditional inversion‐recovery data. Nonexponential behavior is fairly common in solid‐state NMR, and this “exponential decay to zero” approach is

ISSN:1043-7347    

DOI:10.1002/cmr.1820010107

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractCrystallographic alignment of both orthogonal and oblique crystal systemsviastandard camera methods (Weissenberg and Laue methods) is explained. A method to determine whether or not nuclei at symmetry‐related crystal lattice sites are distinguishable by NMR is presented. The constraints of crystallographic symmetry on the symmetry and orientation of the shielding tensor are discusse

ISSN:1043-7347    

DOI:10.1002/cmr.1820010108

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

ISSN:1043-7347    

DOI:10.1002/cmr.1820010103

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY