Nuclear magnetic resonance

N-Heterocyclic carbenes are widely used in organic reactions and coordination chemistry. In the present study, 2,3-dihydro-1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (1) is reacted with diphenyl disulfide, methyl phenyl disulfide, and bis(methylsulfonyl)methane to yield target compounds 5, 6, and 7 respectively.

6p tocectocec 25-05-2020 7 0   Download

Phần 5 trình bày một số phương pháp đặc biệt như: Phương pháp đo góc nghiêng và phương vị của vỉa (Dipmeter), phương pháp quét ảnh thành hệ FMI (Fullbore Formation Microimager), phương pháp cộng hưởng từ hạt nhân NMR (Nuclear Magnetic Resonance). Mời các bạn cùng tham khảo.

14p tangtuy05 25-03-2016 97 12   Download

The solution structure of a synthetic mutant type I antifreeze protein (AFP I) was determined in aqueous solution at pH 7.0 using nuclear magnetic resonance (NMR) spectroscopy. The mutations comprised the replacement of the four Thr residues by Val and the introduction of two additional Lys-Glu salt bridges. The antifreeze activity of this mutant peptide, VVVV2KE, has been previously shown to be similar to that of the wild type protein, HPLC6 (defined here as TTTT).

8p research12 01-06-2013 36 4   Download

The osmoregulated periplasmic glucans (OPGs) produced byRhodobacter sphaeroides, a free-living organism, were isolated by trichloracetic acid treatment and gel permeation chromatography. Compounds obtained were characterized by compositional analysis, matrix-assisted laser desorption ionization mass spectrometry and nuclear magnetic resonance.R. sphaeroidespredominantly synthesizes acyclic glucan containing 18 glucose residues that canbe substituted by one to seven succinyl esters residues at the C6position of some of the glucose residues, and by one or two acetyl resi-dues....

9p research12 29-04-2013 36 1   Download

The lipopolysaccharide (LPS) ofChlamydia trachomatis serotype E was isolated from tissue culture-grown element-ary bodies and analyzed structurally by mass spectrometry and 1 H, 13 Cand31 P nuclear magnetic resonance. The LPS is composed of the same pentasaccharide bisphosphate aKdo-(2–8)-aKdo-(2–4)-aKdo-(2–6)-bGlcN-4P-(1–6)-aGlcN-1P (Kdo is 3-deoxy-a-D-manno-oct-2-ulosonic acid) as reported forC. trachomatisserotype L2[Rund,S.,Lind-ner,B.,Brade,H. and Holst,O. (1999)J. Biol. Chem.274, 16819–16824].

11p tumor12 20-04-2013 39 4   Download

 NMR in solids, like solution-state, relies on the behavior of nuclear spin energy levels in a magnetic field. However, the interactions that affect NMR spectra act differently.  In liquids, molecules reorient and diffuse quickly, leading to narrow isotropic resonances.  In solids, the fixed orientation of individual crystallites leads to a range of resonance frequencies for anisotropic interactions.

14p qdung92ct 03-07-2012 79 5   Download

NMR is an experiment in which the resonance frequencies of nuclear magnetic systems are investigated. NMR always employs some form of magnetic field (usually a strong externally applied field B0) NMR is a form of both absorption and emission spectroscopy, in which resonant radiation is absorbed by an ensemble of nuclei in a sample, a process causing detectable emissions via a magnetically induced electromotive force.

20p qdung92ct 03-07-2012 114 10   Download

Optimal use of genome sequences and gene-expression resources requires powerful phenotyping platforms, including those for systematic analysis of metabolite composition. The most used technologies for metabolite profiling, including mass spectral, nuclear magnetic resonance and enzyme-based approaches, have various advantages and disadvantages, and problems can arise with reliability and the interpretation of the huge datasets produced. These

0p thulanh21 15-11-2011 50 1   Download

Acta Veterinaria Scandinavica Research Tuyển tập các báo cáo nghiên cứu về bệnh học thý y được đăng trên tạp chí Acta Veterinaria Scandinavica cung cấp cho các bạn kiến thức về bệnh thú y đề tài: Proton nuclear magnetic resonance spectroscopy based investigation on propylene glycol toxicosis in a Holstein cow...

9p coxanh_1 22-10-2011 59 6   Download

MRI - Hình cộng hưởng từ (MRI/ Magnetic reconance imaging): Hình cộng hưởng hạt nhân (NMRI/ Nuclear magnetic resonance imaging). Lịch sử MRI: 1940: Felix Block + Edward Furcell. 1971: Raymond Damadian. 1972: Hounsfield - CT.

20p vuilacongaiha 08-07-2010 279 113   Download