Springer us jan 2012 (3 Ergebnisse)

Taschenbuch. Zustand: Neu. Neuware -Recent developments in various areas of chemistry have been decisively influenced by the principles of structure and mechanism and by the ideas of coordination chemistry, in particular by the donor-acceptor approach, A unified view of almost all kinds of molecular forces is provided by quantum mechanics, and for practical purposes have been classified according to model assumptions, namely, dispersion, polarization, electrostatic, and short-range forces. The latter are divided into two- and three-center covalent chemical bonds, metallic bonds, and exchange-repulsion forces. This approach allows statements of principle and systematic analysis. However, quantitative predictions on concrete large systems are virtually impossible, and there are no general rules that account for structural and chemical changes due to intermolecular interactions. Chemists are therefore left with qualitative descriptions in which the changes in electron densities are considered. Such models as the MO theory or the resonance concept unrealistically assume that the nuclei remain in fixed positions. Further difficulties are encountered in the attempted description on the 'nature' of the chemical bond, e.g., the forces involved. In order to avoid these difficulties an extension of the donor-acceptor concept, characterized by the comparison between equilibrium structures in different molecular environments, will be presented in this book. In this way, changes in the positions of the nuclei can be taken into account and the question of the nature of the molecular forces is no longer important.Springer Verlag GmbH, Tiergartenstr. 17, 69121 Heidelberg 296 pp. Englisch.…

Taschenbuch. Zustand: Neu. Neuware - Prostaglandins, Leukotrienes, and Cancer is a multi-volume series that will focus on an emerging area of cancer research. In 1968, R.H. Williams first reported that elevated prostaglandin levels are present in human medullary car cinoma. Since that time, the concept that arachidonic acid metabolites may be in volved in cancer has expanded to include every aspect of the disease from cell transformation through metastasis. Prostaglandins and leukotrienes are generic terms used to describe a family of bioactive lipids produced from unsaturated fatty acids (principally from arachidonic acid) via the cyclooxygenase and lipoxygenase pathways, respec tively. Cyclooxygenase products consist of diverse products such as prosta glandin Ez (PGEz), prostacyclin (PGIz) and thromboxane Az (TXAz), whereas lipoxygenase products consist of hydroperoxy fatty acids and mono-, di- and tri-hydroxy acids including leukotrienes. The precursor fatty acids for the cyclooxygenase and lipoxygenase pathways are present in cellular phospholipids. This finding established an important control point in their biosynthesis-the release of substrate. This occurs in response to numerous stimuli that act at the cell surface. Dr. Bengt Samuelsson's extensive study of the metabolism of pros taglandins indicated that they are rapidly inactivated on a single pass through pulmonary circulation. Thus, they cannot act as circulating hormones and appear to be made on demand in or in the vicinity of target tissues leading to the concept that prostaglandins are local hormones or autocoids.…

Taschenbuch. Zustand: Neu. Neuware - A: Biochemistry of Platinum Complexes in Cancer Chemotherapy.- B: Pharmacological Mechanisms and Toxicology of Platinum Complexes as Antitumor Agents.- C: Clinical Applications of Platinum Complexes.- D: Advances in Antitumor Research with Platinum and Non-Platinum Complexes; Development of New Metal Coordination Compounds: Synthesis and Characterization.- Author Index.…