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991.
Marcin Płosiński Tomasz Laskowski Paweł Sowiński Jan Pawlak 《Magnetic resonance in chemistry : MRC》2012,50(12):818-822
The absolute configurations of all the stereogenic centers of the antibiotic mycoheptin A2 were established upon previously elaborated general procedure, consisting of DQF‐COSY, NOESY, ROESY, HSQC and HMBC experiments as major tools. The structure of mycoheptin A2 without stereochemistry of its aglycone has been reported before. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
992.
Transmission of light through a left-handed slab is studied theoretically. The slab consists of randomly distributed electric and magnetic scatterers. In a practical realization these could be wire and split ring resonators forming a disordered metamaterial. Enhanced transmission close to the middle of the slab is demonstrated. It is explained canalization of source image through self-collimated channels. Existence of self-collimated channels localized on the surface of the slab is demonstrated and a possibility of sub-wavelength imaging by such a system is discussed. 相似文献
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We prove that the inscribed and circumscribed ball conditions, commonly used in finite element analysis, are equivalent in any dimension. 相似文献
997.
This article presents extensions of the Cramér-Wold theorem to measures that may have infinite mass near the origin. Corresponding
results for sequences of measures are presented together with examples showing that the assumptions imposed are sharp. The
extensions build on a number of results and methods concerned with injectivity properties of the Radon transform. Using a
few tools from distribution theory and Fourier analysis we show that the presented injectivity results for the Radon transform
lead to Cramér-Wold type results for measures. One purpose of this article is to contribute to making known to probabilists
interesting results for the Radon transform that have been developed essentially during the 1980s and 1990s. 相似文献
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Performance of homonuclear coupling sign edited (HCSE) experiment applied to detection of signed carbon–carbon couplings is discussed using a set of already measured samples of nine monosubstituted benzenes. It is shown that coupling sign detection is insensitive to the settings of carbon–carbon polarization transfer delays. The HCSE spectra of ten from the total of 43 measured carbon–carbon couplings were considerably influenced by relaxations and proton–proton strong couplings. These effects are quantitatively discussed. The results of HCSE and SLAP experiments are compared. It is shown that the two methods may complement each other in detection of signed carbon–carbon couplings. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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