نتایج جستجو برای: h nmr
تعداد نتایج: 578829 فیلتر نتایج به سال:
Extreme climate events are being recognized as important factors in the effects on crop growth and yield. Increased climatic variability leads to more frequent extreme conditions which may result in crops being exposed to more than one extreme event within a growing season. The aim of this study was to examine the implications of different drought treatments on the protein fractions in grains o...
A Dynamic Nuclear Polarisation (DNP) enhanced solid-state Magic Angle Spinning (MAS) NMR spectrometer operating at 6.7 T is described and demonstrated. The 187 GHz TE(13) fundamental mode of the FU CW VII gyrotron is used as the microwave source for this magnetic field strength and 284 MHz (1)H DNP-NMR. The spectrometer is designed for use with microwave frequencies up to 395 GHz (the TE(16) se...
The 70.6.MHz IrB NMR spectrum of 1,2-B,,C,H,z has been assigned by use of labeled derivatives. The assignments are, in order of increasing field, B(9,12), B(8,10), B(4,5,7,! 1) and B(3,6). Resonances in 1,7-B&H,, are due, in order of increasing field, to B(S,12), B(9,10), B(4,6,8,11) and B(2,3). The ‘H NMR spectrum of 1,2-D,-1,2B,,C,H,, in C,D, contains four quartets at -2.7, -2.5. -2.1, and -1...
Ribonucleic acid structure determination by NMR spectroscopy relies primarily on local structural restraints provided by H–H NOEs and J-couplings. When employed loosely, these restraints are broadly compatible with Aand B-like helical geometries and give rise to calculated structures that are highly sensitive to the force fields employed during refinement. A survey of recently reported NMR stru...
(1)H NMR is now a standard method to determine de novo primary sequence of all sorts of glycans. These last 30 years, tens of thousands of oligosaccharide sequences have been elucidated by NMR spectroscopy in conjunction with other physico-chemical methods including mass spectrometry and gas chromatography. Most of these sequences are now compiled and available in several web databases recently...
(13)C NMR spectroscopic integration employing short relaxation delays was evaluated as a quantitative tool to obtain ratios of diastereomers, regioisomers, constitutional isomers, mixtures of unrelated compounds, peptoids, and sugars. The results were compared to established quantitative methods such as (1)H NMR spectroscopic integration, gas chromatography, and high-performance liquid chromato...
Anilines 1a-h on reaction with potassium thiocyanate and bromine in acetic acid yielded substituted 2-amino[2,1-b][1,3]benzothiazoles 3a-h. The compounds 3a-h on reaction with ethyl acetoacetate and pheylidine acetoacetate, yielded, 2-methyl-4-H-pyrimido[2,1b][1,3]benzothiazole-4-ones 4a-h and ethyl 4-phenyl-2-methyl-4H–pyrimido[2,1b][1,3]benzothiazole-3-carboxylates 5a-h respectively. Pheylidi...
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