نتایج جستجو برای: proton shift
تعداد نتایج: 201000 فیلتر نتایج به سال:
"Pure shift" methods can greatly improve the resolution of proton NMR spectra. However, current pure shift spectra show small periodic artefacts that prevent their use for studying dilute mixture components. A new technique, compatible with all current pure shift methods, is presented that suppresses such sidebands to arbitrary order, allowing ultraclean spectra to be obtained.
In the present paper a comprehensive microstructure analysis of PMMA based on the combination of one-dimensional and twodimensional (TOCSY, HSQC, and HMBC) NMR experiments is reported. To resolve complex resonance assignments, empirical chemical shift modeling supported by the 2D NMR spectroscopy has been done. Rigorous assignments of resonance signals have been done by investigating the one bo...
We have used rapid mixing and quenching techniques to measure the initial ATP synthesis rates and the duration of the ATP synthetic capacity derived from artificially imposed proton gradients and valinomycin-mediated K+ diffusion potentials in chloroplasts. The initial rate of ATP synthesis driven by a K+ diffusion potential was 10-fold slower than that driven by an acid-base transition of equi...
The work is devoted to a consideration of the different determinations of the proton charge radius. It is demonstrated that the results from the elastic electron-proton scattering have to be of a higher uncertainty. A review of the hydrogen Lamb shift measurements and the radius determination from them is also presented.
A hydrogen-bonding interaction between phenobarbital or pentobarbital with phosphatidylcholine in chloroform is indicated by the effects of added phosphatidylcholine on the infrared and proton magnetic resonance spectra of these barbiturates. The nitrogenbound proton of the barbiturate and the orthophosphate moiety of the phosphatidylcholine molecule appear to be involved. The more pronounced e...
The 1H and 15N NMR spectra of several 15N-labeled pyridoxal-5'-phosphate model systems have been measured at low temperature in various aprotic and protic solvents of different polarity, i.e., dichloromethane-d2, acetonitrile-d3, tetrahydrofuran-d8, freon mixture CDF3/CDClF2, and methanol. In particular, the 15N-labeled 5'-triisopropyl-silyl ether of N-(pyridoxylidene)-tolylamine (1a), N-(pyrid...
We show that the interplay between the Coulomb interaction and the strong interaction, which is enhanced in the nuclear surface, leads to a significant upward shift of the proton single–particle levels. This shift affects the position of the calculated proton drip line, a shift towards decreasing Z by several units. The same mechanism is responsible for significant corrections to the mass diffe...
The standard for chemical shift is dilute tetramethylsilane (TMS) in CDCl3, but many measurements are made relative to TMS in other solvents, the proton resonance of the solvent peak or relative to the lock frequency. Here, the chemical shifts of TMS and the proton and deuterium chemical shifts of the solvent signals of several solvents are measured over a wide temperature range. This allows fo...
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