oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 9 )

2019 ( 611 )

2018 ( 704 )

2017 ( 696 )

Custom range...

Search Results: 1 - 10 of 401404 matches for " M. Junker "
All listed articles are free for downloading (OA Articles)
Page 1 /401404
Display every page Item
Intertwining relations of non-stationary Schr?dinger operators
F. Cannata,M. Ioffe,G. Junker,D. Nishnianidze
Physics , 1998, DOI: 10.1088/0305-4470/32/19/309
Abstract: General first- and higher-order intertwining relations between non-stationary one-dimensional Schr\"odinger operators are introduced. For the first-order case it is shown that the intertwining relations imply some hidden symmetry which in turn results in a $R$-separation of variables. The Fokker-Planck and diffusion equation are briefly considered. Second-order intertwining operators are also discussed within a general approach. However, due to its complicated structure only particular solutions are given in some detail.
Statistical filtering for NMR based structure generation
Jochen Junker
Journal of Cheminformatics , 2011, DOI: 10.1186/1758-2946-3-31
Abstract: Nuclear Magnetic Resonance is the most common tool used for the structure elucidation of new compounds. The used 2D NMR experiments like COSY, HSQC, and 13C-HMBC deliver correlation information between atoms that can be translated into connectivity information. Out of these, correlation information from COSY and HSQC experiments can be transcribed directly into connectivity between atoms. But the 13C-HMBC correlations need more attention because of their ambiguity and complexity. Hence the difficulty of the structure elucidation problem depends more on the type of the investigated molecule than on its size. Saturated compounds can usually be assigned unambiguously using mainly COSY and some 13C-HMBC data, whereas condensed heterocycles are problematic due to their lack of protons that could show interatomic connectivities. This ambiguity has driven the development of different software packages to aid in the interpretation of the 13C-HMBC correlation data [1-19] as much as the development of additional correlation experiments [20,21].When the observed connectivity information is used as input for the structure generation program COCON[3,22-24] it will create all compatible constitutional assignments. In the case of unsaturated molecules COCON will usually generate a very large number of possible solutions. Since the solutions will then have to be checked manually for their chemical feasibility and sense, Different efforts have been made to reduce the number solutions. Among others, ranking of the constitutional assignments by chemical shift deviation and/or substructural elements have been tested [25,26] integrated to COCON runs. Unfortunately, the described software could not be made available for the online version of COCON (WEBCOCON at http://cocon.nmr.de webcite), since it uses data protected by Intellectual Property. A different way of handling the result set had to be chosen, and the statistical filter was implemented.The idea behind the filter is, to compare
Theoretical NMR correlations based Structure Discussion
Jochen Junker
Journal of Cheminformatics , 2011, DOI: 10.1186/1758-2946-3-27
Abstract: Nuclear Magnetic Resonance allied with Elemental analysis or high resolution Mass Spectroscopy are the most common tools used for the structure elucidation of new compounds. The used 2D NMR experiments like COSY, HSQC, and 13C-HMBC deliver correlation information between atoms that can be translated into connectivity information. Out of these, correlation information from COSY and HSQC experiments can be transcribed directly into connectivity between atoms. But the 13C-HMBC correlations need more attention because of their ambiguity and complexity. Hence the difficulty of the structure elucidation problem depends more on the type of the investigated molecule than on its size [1]. Saturated compounds can usually be assigned unambiguously using mainly COSY and some 13C-HMBC data, whereas condensed heterocycles are problematic due to their lack of protons that could show interatomic connectivities. This ambiguity has driven the development of different software packages to aid in the interpretation of the 13C-HMBC correlation data [2-20] as much as the development of additional correlation experiments [21,22].Most of these approaches have in common that they work only based on experimental NMR correlation data. COCON [1,4,23,24] has recently been extended with the capability to create a theoretical NMR correlation data set, based on a molecule's suggested constitution. The theoretical data set is used as input data for the structure elucidation software COCON. The resulting set of constitutional assignments indicates how unambiguous NMR would have been able to describe the originally suggested molecule. The freely accessible online version of COCON (WEBCOCON at http://cocon.nmr.de webcite) offers this analysis as "Alternative Constitutions".The data derived from the NMR correlation spectra is the result of magnetization transfer via scalar coupling between the atoms in the molecule of interest. Since the scalar coupling is based on the interatomic bonds, the correlatio
Het irrigatie vraagstuk in Suriname
L. Junker
Nieuwe West-Indische Gids , 1940,
Abstract:
De godsdienst der boschnegers III
L. Junker
Nieuwe West-Indische Gids , 1926,
Abstract:
De benoeming van een grootopperhoofd der Boschnegers
L. Junker
Nieuwe West-Indische Gids , 1947,
Abstract:
Goudexploitatie in Suriname
L. Junker
Nieuwe West-Indische Gids , 1940,
Abstract:
Herinneringen aan het oerwoud
L. Junker
Nieuwe West-Indische Gids , 1941,
Abstract:
Primitief Communisme
L. Junker
Nieuwe West-Indische Gids , 1940,
Abstract:
Herinneringen aan het oerwoud
L. Junker
Nieuwe West-Indische Gids , 1940,
Abstract:
Page 1 /401404
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.