摘要:

AbstractDigital image processing has become well known through the high quality of some spectacular satellite images. It has developed into a discipline in its own right within information science and now finds application, not only in space travel, but also in such diverse fields as, for example, robotics, medical imaging, and television technology. Image processing also occurs, however, in photographic films and biological visual systems. In these systems, too, recorded images are manipulated for better recognition. This poses the question as to whether similar principles of image processing are operative in these different image handling systems.

ISSN:0570-0833    

DOI:10.1002/anie.198916013

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractMetal‐sulfur centers play an important role in the activity of metalloproteins in enzymatic catalysis and the activity of metal sulfides as heterogeneous catalysts. The systematic search for MS model compounds led to the discovery of an interesting and novel structural chemistry, which stems from the numerous coordination possibilities of sulfur ligands. The intention of this review article is to present and outline new approaches to sulfur chemistry from the organometallic point of view. Reactive cyclopentadienyl‐transition metal fragments incorporate elemental sulfur to give polynuclear sulfur‐rich complexes, which can contain either mono‐, di‐ or polysulfido ligands or several such ligands in combined form. The versatile structural chemistry of the complexes formed and their reactivity towards organic, inorganic and organometallic compounds are discussed, and examples of some simple and rational procedures for their synthesis starting from cyclopentadienylcarbonyl‐ and cyclopentadienylhydrido‐complexes are outlined. Their reactivity is manifested in numerous metal‐ and ligandcentered reactions. Finally the, albeit far less extensive, complex chemistry of the other chalcogens (O, Se, Te) is also considered for comparison, thus providing a more detailed survey of particular aspects of this

ISSN:0570-0833    

DOI:10.1002/anie.198916131

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractSilicon and its compounds have made possible the design of new materials, which, from computers to space travel, have helped to shape the technology of our 20th century. Conversely, the demands of new technology have stimulated the fast development of silicon chemistry as part of the “renaissance” of inorganic chemistry. This article uses selected examples of predominantly organosilicon compounds to discuss in simplified terms the measurement and assignment of suitable spectroscopic “molecular fingerprints” as well as the resulting benefit for the preparative chemist. The comparison of “equivalent” states of “chemically related” molecules is emphasized, based on perturbation arguments and supporting quantum‐chemical models. Special attention is given to the relation between structure and energy, which allows us to understand and to predict the connectivity between and the spatial arrangement of silicon “building blocks”, the energy‐dependent electron distribution over the effective nuclear potentials of a molecular framework, and, especially, the partly considerable effects of “silicon substituents” on molecular properties. Future‐directed extensions and applications include polysilane band structures, Rydberg states of chromophores containing silicon centers, redox reactions and ion‐pair formation of silicon‐substituted π systems, and molecular dynamic phenomena in solution or on thermal fragmentation in the gas phase. The main objective is a set of clear and practical rules for interpreting mea

ISSN:0570-0833    

DOI:10.1002/anie.198916271

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198916511

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198916551

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198916571

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198916591

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198916601

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198916621

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198916631

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY