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  • 2010-2014
  • 2005-2009  (50)
  • 1975-1979  (1,451)
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  • 1
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    Die Wissensberechnungsmaschine Wolfram|Alpha (2009)
    Details
    Publication Date: 2020-12-11
    Description: Im Mai 2009 wurde Wolfram|Alpha gestartet, ein Service, der seinen Namen von seinem Entwickler, dem britischen Mathematiker Stephen Wolfram, ableitet. Dem Benutzer soll nicht nur eine Liste von Webseiten als Ergebnis auf Anfragen geliefert werden, sondern Antworten auf konkrete Fragen geben. In diesem Report soll gezeigt werden, warum sichWolframjAlpha von Suchmaschinen abgrenzt und was die Berechnung von Antworten auf natürlichsprachliche Fragen möglich machen kann.
    Description: Wolfram|Alpha was started in May 2009 and it's a service whose name derives from the british mathematician Stephen wolfram. As a result for a request the user is not just supported with a list of websites but with answers for concrete questions. In this report it will be shown why Wolfram|Alpha seperates from search engines and moreover what makes the computation of answers for natural language queries possible.
    Keywords: ddc:004
    Language: German
    Type: reportzib , doc-type:preprint
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  • 2
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    Barrier methods for a control problem from hyperthermia treatment planning (2009)
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    Publication Date: 2019-01-29
    Description: We consider an optimal control problem from hyperthermia treatment planning and its barrier regularization. We derive basic results, which lay the groundwork for the computation of optimal solutions via an interior point path-following method. Further, we report on a numerical implementation of such a method and its performance at an example problem.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 3
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    Transparent boundary conditions for Maxwell's equations: Numerical concepts beyond the PML method (2009)
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    Publication Date: 2016-06-09
    Description: Optical technologies are ubiquitously used in hi-tech devices. As a common feature of such devices one finds structures with dimensions in the order of the wavelength of the used light. To design and produce such devices, the wave nature of light must be taken into account. Accordingly, robust simulation tools are required which are based on rigorously solving Maxwell's equations, the governing equations of light propagation within macroscopic media. This thesis contributes to the modeling and the numerical computation of light scattering problems: Light scattering problems are typically posed on the entire space. The Perfectly-Matched -Layer method (PML) is widely used to restrict the simulation problem onto a bounded computational domain. We propose an adaptive PML method which exhibits a good convergence even for critical problems where standard PML implementations fail. Besides the computation of the near field, that is the electromagnetic field within the computational domain, it is of major interest to evaluate the electromagnetic field in the exterior domain and to compute the far field. So far, this was numerically only possible for simple geometries such as homogeneous exterior domains or layered media. To deal with more complicated devices, for example with waveguide inhomogeneities, we develop an evaluation formula based on the PML solution which allows for an exterior domain field evaluation in a half space above the device. Finally, we generalize the PML method to problems with multiply structured exterior domains. The term “multiply structured exterior domain” is defined in this thesis and means that the exterior domain exhibits several half-infinite structures. Mathematically, this gives rise to various complications. For example, no analytical solutions to Maxwell's equations for standard light sources are available in the exterior domain, which are needed to describe the incoming field in a light scattering problem. To tackle this we propose a new light scattering problem formulation which fits well into the PML method framework and which may be regarded as an extension of classical contributions by Sommerfeld, Wiener and Hopf. An exterior domain evaluation formula for multiply structured exterior domains with an extended illumination is derived as well.
    Keywords: ddc:510
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 4
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    The Coolest Path Problem (2009)
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    Publication Date: 2020-08-05
    Description: We introduce the coolest path problem, which is a mixture of two well-known problems from distinct mathematical fields. One of them is the shortest path problem from combinatorial optimization. The other is the heat conduction problem from the field of partial differential equations. Together, they make up a control problem, where some geometrical object traverses a digraph in an optimal way, with constraints on intermediate or the final state. We discuss some properties of the problem and present numerical solution techniques. We demonstrate that the problem can be formulated as a linear mixed-integer program. Numerical solutions can thus be achieved within one hour for instances with up to 70 nodes in the graph.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 5
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    The MCF-Separator -- Detecting and Exploiting Multi-Commodity Flow Structures in MIPs (2009)
    Details
    Publication Date: 2021-08-05
    Description: Given a general mixed integer program (MIP), we automatically detect block structures in the constraint matrix together with the coupling by capacity constraints arising from multi-commodity-flow formulations. We identify the underlying graph and generate cutting planes based on cuts in the detected network. Our implementation adds a separator to the branch-and-cut libraries of SCIP and CPLEX. We make use of the complemented mixed integer rounding framework (cMIR) but provide a special purpose aggregation heuristic that exploits the network structure. Our separation scheme speeds-up the computation for a large set of MIPs coming from network design problems by a factor of two on average.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 6
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    Co-Reservation of Resources in the Grid (2009)
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    Publication Date: 2016-06-30
    Description: Executing applications in the Grid often requires access to multiple geographically distributed resources. In a Grid environment, these resources belong to different administrative domains, each employing its own scheduling policy. That is, at which time an activity (e.g., compute job, data transfer) is started, is decided by the resource's local management system. In such an environment, the coordinated execution of distributed applications requires guarantees on the quality of service (QoS) of the needed resources. Reserving resources in advance is an accepted means to obtain QoS guarantees from a single provider. The challenge, however, is to coordinate advance reservations of multiple resources. This work presents a system architecture and mechanisms to coordinate multiple advance reservations -- called co-reservations -- for delivering QoS guarantees to complex applications. We formally define the co-reservation problem as an optimization problem. The presented model supports three dimensions of freedom: the start time, the duration and the service level of a reservation. Requests and resources are described in a simple language. After matching the static properties and requirements of either side in a mapping, the reservation mechanism probes information about the future status of the resources. The versatile design of the probing step allows the efficient processing of requests, but also lets the resources express their preferences among the myriads of reservation candidates. Next, the best mapping is found through an implementation of the formal co-reservation model. Then, the mapping has to be secured, i.e., resources need to be allocated to a co-reservation candidate with all-or-nothing semantics. We study several goal-driven sequential and concurrent allocation mechanisms and define schemes for handling allocation failures. Finally, we introduce the concept of virtual resources for seamlessly embedding co-reservations into Grid resource management.
    Description: Die Ausführung von Anwendungen erfordert oft mehrere, geographisch verteilte Ressourcen. In Grid-Umgebungen gehören diese Ressourcen zu verschiedenen administrativen Organisationen, wobei jede ihre eigene Schedulingregeln verwendet. Das bedeutet, zu welcher Zeit eine Aktivität gestartet wird (z.B. ein Rechenjob), wird vom lokalen Ressourcenmanagementsystem entschieden. Die koordinierte Ausführung von verteilten Anwendungen erfordert Dienstgütegarantien für die benötigten Ressourcen. Das Reservieren von Ressourcen im Voraus ist ein Mittel, um Dienstgütegarantien von einem einzelnen Ressourcenanbieter zu erhalten. Die Herausforderung in dieser Arbeit ist, Vorausreservierungen von mehreren Ressourcen zu koordinieren. Es wird ein System für die Koordinierung mehrerer Vorausreservierungen -- Co-Reservierungen genannt -- für die Bereitstellung von Dienstgütegarantien vorgestellt. Wir definieren das Co-Reservierungsproblem als Optimierungsproblem. Das vorgestellte Modell unterstützt drei Freiheitsgrade: die Startzeit, die Dauer und die Dienstgüte einer Reservierung. Anfragen und Ressourcen werden in einer einfachen Sprache beschrieben. Nachdem statische Eigenschaften und Anforderungen beider Seiten überprüft wurden, ermittelt der Reservierungsmechanismus Informationen über den zukünftigen Zustand der Ressourcen. Dieser Schritt ist so allgemein gehalten, daß er sowohl ein effizientes Bearbeiten der Anfragen erlaubt als auch den Ressourcen ermöglicht ihre Präferenzen auszudrücken. Im Anschluss wird die optimale Zuweisung von Anfragen zu Ressourcen ermittelt. Im letzten Schritt muss diese Zuweisung umgesetzt werden, d.h., entweder alle oder keine Ressource wird allokiert. Es werden mehrere sequentielle und parallele Allokationsverfahren vorgestellt sowie deren Auswirkung auf verschiedene Metriken untersucht. Die Einbettung von Co-Reservierungen in das Grid-Ressourcenmanagement wird anhand des Konzeptes der virtuellen Ressource dargestellt.
    Keywords: ddc:004
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 7
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    Veränderungen der Publikations- und Kommunikationswelt: Open Access, Google, etc. (2009)
    Details
    Publication Date: 2020-12-11
    Description: Vorbemerkung Beim Schreiben dieses Artikels, der auf Veränderungen der Kommunikations- und Publikationstechniken und ihre Bedeutung hinweist, ist uns mehr als je zuvor bewusst geworden, wie beschränkt das Medium Papier ist. Es gibt z. B. keine Hyperlinks, durch die man unmittelbar das Erwähnte erleben oder überprüfen kann. Ein schneller Wechsel vom Wort zum Bild, zum Ton oder Video ist nicht möglich. Wer will schon lange URLs abtippen und Medienbrüche erleiden? Wir haben uns daher entschlossen, eine textidentische Version dieses Artikels mit allen URLs – sie liegt Ihnen hier vor – elektronisch anzubieten und in der für die "Gegenworte" (BBAW) gekürzten Fassung nur durch [URL] anzudeuten, dass der Leser an dieser Stelle einfach in der elektronischen Version einen Klick ins Internet machen sollte. Und damit sind wir bereits mitten im Thema.
    Keywords: ddc:020
    Language: German
    Type: reportzib , doc-type:preprint
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  • 8
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    Nonlinear pseudo-Boolean optimization: relaxation or propagation? (2009)
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    Publication Date: 2022-03-14
    Description: Pseudo-Boolean problems lie on the border between satisfiability problems, constraint programming, and integer programming. In particular, nonlinear constraints in pseudo-Boolean optimization can be handled by methods arising in these different fields: One can either linearize them and work on a linear programming relaxation or one can treat them directly by propagation. In this paper, we investigate the individual strengths of these approaches and compare their computational performance. Furthermore, we integrate these techniques into a branch-and-cut-and-propagate framework, resulting in an efficient nonlinear pseudo-Boolean solver.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 9
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    The Steiner Connectivity Problem (2009)
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    Publication Date: 2020-12-15
    Description: The Steiner connectivity problem is a generalization of the Steiner tree problem. It consists in finding a minimum cost set of simple paths to connect a subset of nodes in an undirected graph. We show that polyhedral and algorithmic results on the Steiner tree problem carry over to the Steiner connectivity problem, namely, the Steiner cut and the Steiner partition inequalities, as well as the associated polynomial time separation algorithms, can be generalized. Similar to the Steiner tree case, a directed formulation, which is stronger than the natural undirected one, plays a central role.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 10
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    Ergebnisse aus dem BVB-KOBV-Entwicklungsprojekt "Literaturverwaltungsprogramme": Handreichung für Bibliotheken (2009)
    Details
    Publication Date: 2020-12-11
    Description: Zwischen dem Bibliotheksverbund Bayern (BVB) und dem Kooperativen Bibliotheksverbund Berlin-Brandenburg (KOBV) besteht seit Ende 2007 eine Strategische Allianz, die auf zwei Säulen beruht: einer langfristigen Entwicklungspartnerschaft einerseits und der Kooperation im Dienstleistungsbereich mit der Integration der Verbundkataloge andererseits. Ende 2008 wurde das erste Entwicklungsprojekt "Literaturverwaltungsprogramme" abgeschlossen, dessen Ergebnisse in dieser Handreichung in Form von Handlungsempfehlungen für Bibliotheken vorgestellt werden. Ziel des Projekts war es, den Datenaustausch zwischen den Bibliotheks- und Verbundkatalogen des BVB und KOBV und gängigen Literaturverwaltungsprogrammen zu optimieren. Neben Handlungsempfehlungen für die Implementierung neuer Exportschnittstellen und die Verbesserung bestehender Exportmöglichkeiten werden Hinweise auf verbesserte Nutzerführung gegeben. Die Empfehlungen beziehen sich vorwiegend auf den Datenaustausch zwischen den Bibliothekssystemen Aleph 500, MetaLib und WebOPAC/InfoGuide und den Literaturverwaltungsprogrammen Citavi, EndNote, RefWorks und Zotero.
    Keywords: ddc:020
    Language: German
    Type: reportzib , doc-type:preprint
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  • 11
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    Planning Problems in Public Transit (2009)
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    Publication Date: 2020-08-05
    Description: Every day, millions of people are transported by buses, trains, and airplanes in Germany. Public transit (PT) is of major importance for the quality of life of individuals as well as the productivity of entire regions. Quality and efficiency of PT systems depend on the political framework (state-run, market oriented) and the suitability of the infrastructure (railway tracks, airport locations), the existing level of service (timetable, flight schedule), the use of adequate technologies (information, control, and booking systems), and the best possible deployment of equipment and resources (energy, vehicles, crews). The decision, planning, and optimization problems arising in this context are often gigantic and “scream” for mathematical support because of their complexity. This article sketches the state and the relevance of mathematics in planning and operating public transit, describes today’s challenges, and suggests a number of innovative actions. The current contribution of mathematics to public transit is — depending on the transportation mode — of varying depth. Air traffic is already well supported by mathematics. Bus traffic made significant advances in recent years, while rail traffic still bears significant opportunities for improvements. In all areas of public transit, the existing potentials are far from being exhausted. For some PT problems, such as vehicle and crew scheduling in bus and air traffic, excellent mathematical tools are not only available, but used in many places. In other areas, such as rolling stock rostering in rail traffic, the performance of the existing mathematical algorithms is not yet sufficient. Some topics are essentially untouched from a mathematical point of view; e.g., there are (except for air traffic) no network design or fare planning models of practical relevance. PT infrastructure construction is essentially devoid of mathematics, even though enormous capital investments are made in this area. These problems lead to questions that can only be tackled by engineers, economists, politicians, and mathematicians in a joint effort. Among other things, the authors propose to investigate two specific topics, which can be addressed at short notice, are of fundamental importance not only for the area of traffic planning, should lead to a significant improvement in the collaboration of all involved parties, and, if successful, will be of real value for companies and customers: • discrete optimal control: real-time re-planning of traffic systems in case of disruptions, • model integration: service design in bus and rail traffic. Work on these topics in interdisciplinary research projects could be funded by the German ministry of research and education (BMBF), the German ministry of economics (BMWi), or the German science foundation (DFG).
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 12
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    Solving Steel Mill Slab Problems with Branch and Price (2009)
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    Publication Date: 2020-08-05
    Description: The steel mill slab design problem from the CSPLib is a binpacking problem that is motivated by an application of the steel industry and that has been widely studied in the constraint programming community. Recently, several people proposed new models and methods to solve this problem. A steel mill slab library was created which contains 380 instances. A closely related binpacking problem called multiple knapsack problem with color constraints, originated from the same industrial problem, were discussed in the integer programming community. In particular, a simple integer programming for this problem has been given by Forrest et al. [3]. The aim of this paper is to bring these different studies together. Moreover, we adopt the model of [3] for the steel mill slab problem. Using a state of the art integer program solver, this model is capable to solve all instances of the steel mill slab library, mostly in less than one second, to optimality. We improved, thereby, the solution value of 76 instances.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 13
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    On the Hardness of Finding Small Shortest Path Routing Conflicts (2009)
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    Publication Date: 2020-08-05
    Description: Nowadays most data networks use shortest path protocols such as OSPF or IS-IS to route traffic. Given administrative routing lengths for the links of a network, all data packets are sent along shortest paths with respect to these lengths from their source to their destination. One of the most fundamental problems in planning shortest path networks is to decide whether a given set of routing paths forms a valid routing and, if this is not the case, to find a small subset of the given paths that cannot be shortest paths simultaneously for any routing lengths. In this paper we show that it is NP-hard to approximate the size of the smallest shortest path conflict by a factor less than 7/6.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 14
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    A Binary Quadratic Programming Approach to the Vehicle Positioning Problem (2009)
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    Publication Date: 2020-08-05
    Description: The Vehicle Positioning Problem (VPP) consists of the assignment of vehicles (buses, trams or trains) of a public transport or railway company to parking positions in a depot and to timetabled trips. Such companies have many different types of vehicles, and each trip can be performed only by vehicles of some of these types. These assignments are non-trivial due to the topology of depots. The parking positions are organized in tracks, which work as one- or two-sided stacks or queues. If a required type of vehicle is not available in the front of any track, shunting movements must be performed in order to change vehicles' positions, which is undesirable and should be avoided. In this text we present integer linear and non-linear programming formulations for some versions of the problem and compare them from a theoretical and a computational point of view.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 15
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    Statistical Error Estimation and Grid-free Hierarchical Refinement in Conformation Dynamics (2009)
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    Publication Date: 2020-03-11
    Description: The understanding of geometric structures and dynamical properties of molecular conformations gives insight into molecular long-term behavior. The identification of metastable conformations together with their life times and transition patterns is the intention of conformation dynamics. Conformation dynamics is a multi-scale approach that leads to a reduced description of the dynamical system in terms of a stochastic transition probability matrix. The present thesis deals with the error analysis of computed matrices and the resulting matrix functions. Since conformational membership vectors, as they are computed by the Robust Perron Cluster Analysis (PCCA+), form an invariant subspace of the transition matrix, subspace-based error estimators are of particular interest. The decomposition of the state space into basis functions and the approximation of integrals by Monte-Carlo quadrature give rise to row-wise correlated random matrices, for which stochastic norms are computed. Together with an appropriate statistical model for the distribution of matrix rows, this allows for the calculation of error bounds and error distributions of the invariant subspace and other variables of interest. Equilibration of errors among the basis functions can be achieved by enhanced sampling in regions where the trajectories are mixing slowly. Hierarchical refinement of such basis functions systematically improves the clustering into metastable conformations by reducing the error in the corresponding invariant subspace. These techniques allow for an evaluation of simulation results and pave the way for the analysis of larger molecules. Moreover, the extension of PCCA+ to non-reversible Markov chains, verified by the corresponding perturbation theory, and the modification of the objective function for the case of soft membership vectors represent a further generalization of the clustering method, thus continuing the development from PCCA over PCCA+ to PCCA++. The methods developed in this thesis are useful for but not limited to conformation dynamics. In fact, they are applicable to a broader class of problems which combine domain decomposition with Monte-Carlo quadrature. Possible application areas may include the chemical master equation or quantum dynamical systems.
    Description: Das Verständnis von geometrischen Strukturen und dynamischen Eigenschaften molekularer Konformationen ist essentiell für die Vorhersage des Langzeitverhaltens von Molekülen. Die Identifikation metastabiler Konformationen sowie die Bestimmung von Übergangswahrscheinlichkeiten und Haltezeiten sind Bestandteil der Konformationdynamik. Dabei handelt es sich um eine Mehrskalenmethode, die auf eine reduzierte Beschreibung des Systems mittels einer stochastischen Übergangsmatrix führt. In der vorliegenden Dissertation wurde untersucht, wie man die Genauigkeit der Matrizen sowie der daraus berechneten Größen quantifizieren kann. Im Mittelpunkt stehen dabei Fehlerschätzer für den invarianten Unterraum, da die rechten Eigenvektoren als Grundlage der Robusten Perron Cluster Analyse (PCCA+) zur Identifizierung der metastabilen Konformationen dienen. Die Zerlegung des Zustandsraumes in Basisfunktionen sowie die Approximation der Matrixeinträge mittels Monte-Carlo-Quadratur führen zu zeilenweise korrelierten Zufallsmatrizen. Mit Hilfe einer stochastischen Norm sowie einem geeigneten statistischen Modell für die Verteilung der Matrixzeilen können u.a. Fehlerschranken und -verteilungen für den invarianten Unterraum brechnet werden. Eine Equilibrierung des Fehlers zwischen den Basisfunktionen kann durch erweitertes Sampling in solchen Regionen erreicht werden, in denen die Trajektorien nur langsam mischen.Eine hierarchische Zerlegung dieser Basisfunktionen verbessert systematisch die Zerlegung in metastabile Konformationen, indem sie den Fehler im invarianten Unterraum reduziert. Diese Techniken gestatten eine Evaluierung der Simulationsergebnisse und ebnen den Weg zur Behandlung komplexerer Moleküle. Desweiteren wurden Verallgemeinerungen der PCCA+ untersucht. Die Erweiterung der PCCA+ auf nicht-reversible Markov-Ketten sowie die Modifizierung der Zielfunktion für den Fall der weichen Clusterung setzen die Entwicklung von der PCCA über PCCA+ zu PCCA++ fort. Somit können neue Anwendungsfelder für dieses Cluster-Verfahren erschlossen werden. Die Methoden wurden zwar in Rahmen der Konformationsdynamik entwickelt, jedoch lassen sie sich auf eine weite Problemklasse anwenden, in der Gebietszerlegungsverfahren mit Monte-Carlo-Quadratur kombiniert werden. Mögliche Anwendungsgebiete umfassen die chemische Master-Gleichung oder quantenchemische Systeme.
    Keywords: ddc:510
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 16
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    Hyperdeterminants as integrable discrete systems (2009)
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    Publication Date: 2020-12-11
    Description: We give the basic definitions and some theoretical results about hyperdeterminants, introduced by A.~Cayley in 1845. We prove integrability (understood as $4d$-consistency) of a nonlinear difference equation defined by the $2 \times 2 \times 2$ - hyperdeterminant. This result gives rise to the following hypothesis: the difference equations defined by hyperdeterminants of any size are integrable. We show that this hypothesis already fails in the case of the $2\times 2\times 2\times 2$ - hyperdeterminant.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 17
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    A Set Partitioning Approach to Shunting (2009)
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    Publication Date: 2020-08-05
    Description: The Vehicle Positioning Problem (VPP) is a classical combinatorial optimization problem in public transport planning. A number of models and approaches have been suggested in the literature, which work for small problems, but not for large ones. We propose in this article a novel set partitioning model and an associated column generation solution approach for the VPP. The model provides a tight linear description of the problem. The pricing problem, and hence the LP relaxation itself, can be solved in polynomial resp. pseudo-polynomial time for some versions of the problems.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 18
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    Solving Large-scale Open Pit Mining Production Scheduling Problems by Integer Programming (2009)
    Details
    Publication Date: 2020-08-05
    Description: Since the initial application of mathematical optimisation methods to mine planning in 1965, the Lerchs-Grossmann algorithm for computing the ultimate pit limit, operations researchers have worked on a variety of challenging problems in the area of open pit mining. This thesis focuses on the open pit mining production scheduling problem: Given the discretisation of an orebody as a block model, determine the sequence in which the blocks should be removed from the pit, over the lifespan of the mine, such that the net present value of the mining operation is maximised. In practise, when some material has been removed from the pit, it must be processed further in order to extract the valuable elements contained therein. If the concentration of valuable elements is not sufficiently high, the material is discarded as waste or stockpiled. Realistically-sized block models can contain hundreds of thousands of blocks. A common approach to render these problem instances computationally tractable is the aggregation of blocks to larger scheduling units. The thrust of this thesis is the investigation of a new mixed-integer programming formulation for the open pit mining production scheduling problem, which allows for processing decisions to be made at block level, while the actual mining schedule is still computed at aggregate level. A drawback of this model in its full form is the large number of additional variables needed to model the processing decisions. One main result of this thesis shows how these processing variables can be aggregated efficiently to reduce the problem size significantly, while practically incurring no loss in net present value. The second focus is on the application of lagrangean relaxation to the resource constraints. Using a result of Möhring et al. (2003) for project scheduling, the lagrangean relaxation can be solved efficiently via minimum cut computations in a weighted digraph. Experiments with a bundle algorithm implementation by Helmberg showed how the lagrangean dual can be solved within a small fraction of the time required by standard linear programming algorithms, while yielding practically the same dual bound. Finally, several problem-specific heuristics are presented together with computational results: two greedy sub-MIP start heuristics and a large neighbourhood search heuristic. A combination of a lagrangean-based start heuristic followed by a large neighbourhood search proved to be effective in generating solutions with objective values within a 0.05% gap of the optimum.
    Keywords: ddc:510
    Language: English
    Type: masterthesis , doc-type:masterThesis
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    Moisture-Gravity Wave Interactions in a Multiscale Environment (2009)
    Details
    Publication Date: 2016-06-09
    Description: Starting from the conservation laws for mass, momentum and energy together with a three species, bulk microphysic model, a model for the interaction of internal gravity waves and deep convective hot towers is derived by using multiscale asymptotic techniques. From the resulting leading order equations, a closed model is obtained by applying weighted averages to the smallscale hot towers without requiring further closure approximations. The resulting model is an extension of the linear, anelastic equations, into which moisture enters as the area fraction of saturated regions on the microscale with two way coupling between the large and small scale. Moisture reduces the effective stability in the model and defines a potential temperature sourceterm related to the net effect of latent heat release or consumption by microscale up- and downdrafts. The dispersion relation and group velocity of the system is analyzed and moisture is found to have several effects: It reduces energy transport by waves, increases the vertical wavenumber but decreases the slope at which wave packets travel and it introduces a lower horizontal cutoff wavenumber, below which modes turn into evanescent. Further, moisture can cause critical layers. Numerical examples for steadystate and timedependent mountain waves are shown and the effects of moisture on these waves are investigated.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    1D-Reduktion thermal signifikanter Aderstränge in der Hyperthermie-Modellierung (2009)
    Details
    Publication Date: 2019-01-29
    Description: In dieser Arbeit wird ein neuer Ansatz zur Modellierung von thermal signifikanten Gefäßsträngen im Hyperthermie-Kontext betrachtet. Ausgehend von einer Konvektions-Diffusions-Gleichung wird durch Reskalierung des Massenflussterms eine Reduktion des Adergebietes auf eine 1D-Struktur erreicht. Nach numerischen Vorbetrachtungen wird die Grenzgleichung innerhalb einer verallgemeinerten Sobolev-Algebra formuliert. Die Untersuchung der Lösungsfamilie in klassischen Funktionenräumen zeigt, dass deren schwacher Grenzwert die Lösung der korrespondierenden Diffusions-Gleichung ist. Die Diskretisierung einer formalen Grenzgleichung mit Linienstromanteil stellt jedoch eine gute Approximation an die Diskretisierung des ursprünglichen Problems dar, wenn man die lokale Maschenweite an die Gefäßradien koppelt und bei erhöhtem Genauigkeitsbedarf auf ein vollständiges 3D-Modell umschaltet.
    Keywords: ddc:510
    Language: German
    Type: masterthesis , doc-type:masterThesis
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    Ein Peer-to-Peer System mit Bereichsabfragen in PlanetLab (2009)
    Details
    Publication Date: 2016-06-30
    Description: Aktuelle Entwicklungen zeigen, dass Peer-to-Peer (P2P) Anwendungen wie Skype oder Bittorrent im Internet immer mehr an Bedeutung gewinnen. In den letzten Jahren hat es einen explosionsartigen Anstieg an Nutzern und Daten in solchen Netzen gegeben. Dabei stellt der eigentliche Dateitransfer zwischen zwei Rechnern kein großes Problem mehr dar und auch der Speicherbedarf für die große Menge an Daten kann durch die Weiterentwicklung der Hardware gut gedeckt werden. Das eigentliche Problem liegt vielmehr darin, den Rechner zu finden, der die gewünschten Daten hat. Client-Server Architekturen, wie zum Beispiel Napster, haben sich als ungünstig herausgestellt. Wenige Server, die eine große Anzahl an Clients bedienen müssen, sind einerseits sehr anfällig gegenüber Angriffen und Ausfällen (Single Point of Failure)und kommen auch nicht mit der ständig wachsenden Anzahl an Nutzern zurecht. Verteilte Hashtabellen (DHT) bieten hier einen guten Lösungsansatz, der mit einer großen Anzahl an Nutzern skaliert und ausfallsicher ist. Andere dezentrale Lösungen, wie zum Beispiel das P2P Netzwerk Gnutella haben zwar das Problem des Single Point of Failure gelöst, jedoch haben sie starke Nachteile bei der Suche nach Keys. Bei einer Suche wird ein Broadcast verwendet (jeder schickt die Anfrage an jeden weiter) und damit ein enormer Netzwerkverkehr erzeugt. In "Why Gnutella Can't Scale. No, Really" wird erklärt, dass eine Suchanfrage bei Standardeinstellungen in der Clientsoftware einen Netzwerkverkehr von 17MB erzeugt. Deswegen wird zusätzlich eine Lösung benötigt, die Keys und Values geordnet verteilt, damit sie gezielt gesucht werden können. Aus diesem Grund beschäftigt sich die folgende Arbeit mit einer völlig dezentralen Architektur, die außerdem eine sinnvolle Platzierung der Keys vornimmt. Die dezentrale Architektur hat den Vorteil, dass die Endgeräte den Hauptteil des Dienstes selbst erbringen und damit jeder zusätzliche Teilnehmer seine eigenen Ressourcen beisteuert. Diese Arbeit präsentiert Chord#, eine dezentrale, skalierbare und selbstorganisierende verteilte Hashtabelle. Chord# wurde ausgewählt, da in dieser Arbeit auch Wert auf Bereichsabfragen gelegt wurde. Diese sind zum Beispiel bei dem Chord Algorithmus nicht möglich, da dieser eine Hashfunktion für die Keys verwendet und somit die Daten zwar gleichmäßig aber unsortiert auf die Teilnehmer verteilt. Es wird in dieser Arbeit gezeigt, dass mit Hilfe von Chord# auch ohne die Hashfunktion gute Ergebnisse erzielt werden. Außerdem können durch den Verzicht auf die Hashfunktion Bereichsabfragen ermöglicht werden. Dafür wird der Chord# Algorithmus in Java implementiert (ca. 1500 Zeilen Code) und in dem Forschungsnetz PlanetLab ausführlich auf Laufzeiten, Instandhaltungskosten und Skalierung getestet.
    Description: Recent developments show that peer-to-peer (p2p) applications, such as Skype or Bittorrent have become increasingly important in the internet. Over the last years there has been a rapid growth of both users and data in such networks. However, the actual file transfer between two peers is not really an issue anymore. The same holds true for data storage, since the new hardware grants users enough space to store their data. The real problem is finding the peers that possess the desired data. Client-server architectures like Napster have proven to be ineffective addressing that problem. One or few servers being responsible for many peers are vulnerable to attacks or failures (single point of failure). Additionally, they are unable to cope with the rapidly growing number of peers. Distributed hashtables (DHT) are a good approach to solve these problems, since they scale nicely with large numbers of peers and provide a high tolerance for errors. Other decentralized solutions like the p2p network Gnutella solved the problem of Single Point of Failure but show considerable disadvantages when searching for keys. The peers in Gnutella use a broadcast (sending the message to all peers they know)resulting in massive traffic. According to "Why Gnutella Can't Scale. No, Really.", each search using standard client settings yields 17MB traffc. This calls for a different solution, distributing keys and values to peers quickly and efficiently so they can be found fast. For that reason this thesis focuses on a fully distributed architecture using organized key placement. One major advantage of distributed architecture is the fact, that the peers do most of the work themselves. This way, new peers joining the network add resources to it. This thesis presents Chord#, a scalable, self-organizing and completely decentralized DHT. It has been chosen due to its capability to allow range queries. The regular Chord algorithm does not support range queries, because of the hashfunction it uses to evenly distribute the keys among the peers. This results in similar or logical coherent keys most likely not being close together in the network. This thesis shows Chord# achieving same results as Chord - regarding performance costs - without the hashfunction. In dropping the hashfunction this algorithm allows the use of range queries. The Chord# algorithm is implemented in Java (about 1500 lines of code) and thoroughly tested in the research network PlanetLab. The results are evaluated regarding performance, maintenance and scalability.
    Keywords: ddc:004
    Language: German
    Type: masterthesis , doc-type:masterThesis
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    DHT Load Balancing with Estimated Global Information (2009)
    Details
    Publication Date: 2017-11-02
    Description: One of the biggest impacts on the performance of a Distributed Hash Table (DHT), once established, is its ability to balance load among its nodes. DHTs supporting range queries for example suffer from a potentially huge skew in the distribution of their items since techniques such as consistent hashing can not be applied. Thus explicit load balancing schemes need to be deployed. Several such schemes have been developed and are part of recent research, most of them using only information locally available in order to scale to arbitrary systems. Gossiping techniques however allow the retrieval of fairly good estimates of global information with low overhead. Such information can then be added to existing load balancing algorithms that can use the additional knowledge to improve their performance. Within this thesis several schemes are developed that use global information like the average load and the standard deviation of the load among the nodes to primarily reduce the number of items an algorithm moves to achieve a certain balance. Two novel load balancing algorithms have then been equipped with implementations of those schemes and have been simulated on several scenarios. Most of these variants show better balance results and move far less items than the algorithms they are based on. The best of the developed algorithms achieves a 15-30% better balance and moves only about 50-70% of the number of items its underlying algorithm moves. This variation is also very robust to erroneous estimates and scales linearly with the system size and system load. Further experiments with self-tuning algorithms that set an algorithm’s parameter according to the system’s state show that even more improvements can be gained if additionally applied. Such a variant based on the algorithm described by Karger and Ruhl shows the same balance improvements of 15-30% as the variant above but reduces the number of item movements further to 40-65%.
    Keywords: ddc:004
    Language: English
    Type: masterthesis , doc-type:masterThesis
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    Undercover – a primal heuristic for MINLP based on sub-MIPs generated by set covering (2009)
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    Publication Date: 2022-03-14
    Description: We present Undercover, a primal heuristic for mixed-integer nonlinear programming (MINLP). The heuristic constructs a mixed-integer linear subproblem (sub-MIP) of a given MINLP by fixing a subset of the variables. We solve a set covering problem to identify a minimal set of variables which need to be fixed in order to linearise each constraint. Subsequently, these variables are fixed to approximate values, e.g. obtained from a linear outer approximation. The resulting sub-MIP is solved by a mixed-integer linear programming solver. Each feasible solution of the sub-MIP corresponds to a feasible solution of the original problem. Although general in nature, the heuristic seems most promising for mixed-integer quadratically constrained programmes (MIQCPs). We present computational results on a general test set of MIQCPs selected from the MINLPLib.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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    Comparing MIQCP solvers to a specialised algorithm for mine production scheduling (2009)
    Details
    Publication Date: 2020-08-05
    Description: In this paper we investigate the performance of several out-of-the box solvers for mixed-integer quadratically constrained programmes (MIQCPs) on an open pit mine production scheduling problem with mixing constraints. We compare the solvers BARON, Couenne, SBB, and SCIP to a problem-specific algorithm on two different MIQCP formulations. The computational results presented show that general-purpose solvers with no particular knowledge of problem structure are able to nearly match the performance of a hand-crafted algorithm.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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    Strategien für die Zukunft der regionalen Informationsinfrastruktur - der Kooperative Bibliotheksverbund Berlin-Brandenburg (KOBV) (2009)
    Details
    Publication Date: 2020-12-11
    Description: Eines der Hauptanliegen bei der Initiierung des Kooperativen Bibliotheksverbundes Berlin-Brandenburg (KOBV) war die Schaffung einer modernen, leistungsfähigen Informationsinfrastruktur unter Einbeziehung möglichst aller Bibliotheken der in ihrer Dichte und Vielfalt in Deutschland einmaligen Bibliothekslandschaft. Sie wurde beim Aufbau des KOBV durch die Wahl des Verbundmodelles mit seinen offenen, integrativen Strukturen befördert. Die Ziele und Strategien des KOBV leiten sich aus dem Grundauftrag der Bibliotheken her, ihre NutzerInnen optimal mit Medien und Informationen zu versorgen. Mit dem KOBV haben die Bibliotheken eine gemeinsame Plattform und ein regionales Netzwerk geschaffen, mit deren Hilfe sie die Informationsinfrastruktur in Berlin und Brandenburg zusammen aufgebaut und grundlegend verbessert haben. Nach rund elf Jahren ist der KOBV in eine neue Phase eingetreten, indem er – unter Wahrung seiner institutionellen Eigenständigkeit – eine Strategische Allianz mit dem Bibliotheksverbund Bayern (BVB) eingegangen ist und die bislang auf die Region bezogene Kooperation der Bibliotheken überregional ausgeweitet hat. Wenn auch die Universalbibliotheken des KOBV in dieser Zusammenarbeit einen Kurswechsel zur zentralen Katalogisierung vollziehen, bedeutet dies für den KOBV insgesamt keinen Paradigmenwechsel: Er bleibt ein dezentraler Verbund und wird sein flexibles technisches Mischkonzept von verteilter und zentraler Datenhaltung fortführen. Dieses lässt den Bibliotheken die Freiheit zu entscheiden, ob sie zentral oder dezentral katalogisieren möchten. Die KOBV-Zentrale, die im KOBV keine Aufgaben in der Katalogisierung wahrnimmt, wird wie bislang allen Mitgliedsbibliotheken die ASP-Dienste und weiteren Angebote gleichermaßen zur Verfügung stellen und die Dienstleistungen für NutzerInnen und Bibliotheken weiter ausbauen. Mit dem vorhandenen Know How, der eingesetzten modernen Technologie und der strategischen Entscheidung, Ressourcen und Kompetenzen mit dem BVB zu bündeln und durch verbundübergreifende arbeitsteilige Verfahren Synergien zu gewinnen, ist der KOBV gut aufgestellt, um die Herausforderungen der kommenden Jahre anzugehen und das Leistungsspektrum der KOBV-Bibliotheken durch die Entwicklung neuer Dienste auszuweiten.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
    Format: application/pdf
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    Ein eingebettetes Hauptspeicher-Datenbanksystem mit Snapshot-Reads (2009)
    Details
    Publication Date: 2020-12-15
    Description: Entwurf und Entwicklung eines eingebetteten Hauptspeicher-Datenbanksystems mit Snapshot-Reads.
    Description: Design and implementation of an embedded main memory database with snapshot reads.
    Keywords: ddc:004
    Language: German
    Type: masterthesis , doc-type:masterThesis
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    On sojourn times in M/GI systems under state-dependent processor sharing (2009)
    Details
    Publication Date: 2020-08-05
    Description: We consider a system with Poisson arrivals and i.i.d. service times. The requests are served according to the state-dependent processor sharing discipline, where each request receives a service capacity which depends on the actual number of requests in the system. The linear systems of PDEs describing the residual and attained sojourn times coincide for this system, which provides time reversibility including sojourn times for this system, and their minimal non negative solution gives the LST of the sojourn time $V(\tau)$ of a request with required service time $\tau$. For the case that the service time distribution is exponential in a neighborhood of zero, we derive a linear system of ODEs, whose minimal non negative solution gives the LST of $V(\tau)$, and which yields linear systems of ODEs for the moments of $V(\tau)$ in the considered neighborhood of zero. Numerical results are presented for the variance of $V(\tau)$. In case of an M/GI/2-PS system, the LST of $V(\tau)$ is given in terms of the solution of a convolution equation in the considered neighborhood of zero. For bounded from below service times, surprisingly simple expressions for the LST and variance of $V(\tau)$ in this neighborhood of zero are derived, which yield in particular the LST and variance of $V(\tau)$ in M/D/2-PS.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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    E-Learning and the Working Mathematician (2009)
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    Publication Date: 2020-12-11
    Description: Eigentlich war der erste Autor nur zu einem Grußwort zur Tagung „GML² 2009 - Grundfragen Multi¬medialen Lehrens und Lernens“ eingeladen. Daraus wurde ein E-Learning-bezogener Vortrag, der – basierend auf Erfahrungen im Fach Mathematik – einen kritischen Blick auf die E-Learning-Szene in Deutschland wirft und diese mit entsprechenden Aktivitäten weltweit vergleicht. Dies ist die in seinen mathematischen Teilen gekürzte, in den E-Learning-Anteilen ein wenig erweiterte schriftliche Fassung des Vortrags. Der Artikel stammt nicht von E-Learning-Spezialisten sondern von Personen, die sich seit fast zwanzig Jahren mit elektronischer Information und Kommunikation (kurz: IuK) – insbesondere in der Mathematik – beschäftigen. Nach einer Definition von Michael Kerres kennzeichnet der Begriff E-Learning (electronic learning – elektronisch unterstütztes Lernen) alle Formen von Lernen, bei denen digitale Medien für die Präsentation und Distribution von Lernmaterialien und/oder zur Unterstützung zwischenmenschlicher Kommunikation zum Einsatz kommen, siehe z.B. http://de.wikipedia.org/wiki/E-Learning. IuK und E-Learning haben nach dieser Begriffsbildung viele Berührungspunkte. Deswegen wagen wir es, unsere positiven und negativen Erfahrungen im Bereich IuK in diesem Eröffnungsvortrag zu berichten, einige Entwicklungslinien zu vergleichen und eine eigene Kurzversion der Definition von E-Learning (besser E-Teaching and -Learning) voranzustellen: „Lehren und Lernen mit Unterstützung elektronischer Hilfsmittel“.
    Keywords: ddc:510
    Language: German
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    Ein Userspace-Dateisystem zur Verwaltung von Grid-Daten (2009)
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    Publication Date: 2016-06-30
    Description: Das Ziel dieser Arbeit ist die Schaffung einer Zugriffs-Komponente für das Grid-Datenmanagement-System ZIB-DMS, das dessen transparente Einbindung in den Verzeichnisbaum eines Linux-Systems erlaubt. Dazu wird unter Verwendung des FUSE-Rahmenwerkes ein Userspace-Dateisystem mit Anbindung an das ZIB-DMS konzipiert und implementiert. Im Fokus stehen dabei die Abbildung der erweiterten Verwaltungsmechanismen des Systems auf die limitierte Schnittstelle hierarchischer Dateisysteme und die dazu notwendigen Änderungen am ZIB-DMS.
    Description: The goal of this work is to create an access component for the Grid data management system ZIB-DMS, that allows a transparent integration into the directory tree of a Linux system. For this purpose the FUSE framework is used to design and implement a userspace file system with connections to the ZIB-DMS. The focus is on the mapping of the extended management mechanisms of the system to the limited interface of hierarchical file systems and the therefore necessary changes to ZIB-DMS.
    Keywords: ddc:004
    Language: German
    Type: masterthesis , doc-type:masterThesis
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    Transactional DHT Algorithms (2009)
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    Publication Date: 2021-01-22
    Description: We present a framework for transactional data access on data stored in a DHT. It allows to atomically read and write items and to run distributed transactions consisting of a sequence of read and write operations on the items. Items are symmetrically replicated in order to achieve durability of data stored in the SON. To provide availability of items despite the unavailability of some replicas, operations on items are quorum-based. They make progress as long as a majority of replicas can be accessed. Our framework processes transactions optimistically with an atomic commit protocol that is based on Paxos atomic commit. We present algorithms for the whole framework with an event based notation. Additionally we discuss the problem of lookup inconsistencies and its implications on the one-copy serializability property of the transaction processing in our framework.
    Keywords: ddc:004
    Language: English
    Type: reportzib , doc-type:preprint
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    Planning Teams with Semantic Web Technologies (2009)
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    Publication Date: 2020-12-11
    Description: When planning teams for projects with specific goals, employees of a company have to group together so well, that all necessary knowledge for conquering the project’s challenges are met within the member’s skills. A tool that facilitates semantic web technologies can support the team recruiter, who is responsible for chosing the members of the team, in terms of finding the most efficient combinations of the company’s employees based on their expertises.
    Keywords: ddc:004
    Language: English
    Type: reportzib , doc-type:preprint
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    Optimal Design of Survivable Multi-layer Telecommunication Networks (2009)
    Details
    Publication Date: 2020-08-05
    Description: Telecommunication transport networks consist of a stack of technologically different subnetworks, so-called layers, which are strongly interdependent. For example, one layer may correspond to an Internet (IP) backbone network whose links are realized by lightpath connections in an underlying optical fiber layer. To ensure that the network can fulfill its task of routing all communication requests, the inter-layer dependencies have to be taken into account already in the planning phase of the network. This is particularly important with survivability constraints, where connections in one layer have to be protected against cable cuts or equipment failures in another layer. The traditional sequential planning approach where one layer is optimized after the other cannot properly take care of the inter-layer dependencies; this can only be achieved with an integrated planning of several network layers at the same time. This thesis provides mathematical models and algorithmic techniques for the integrated optimization of two network layers with survivability constraints. We describe a multi-layer network design problem which occurs in various technologies, and model it mathematically using mixed-integer programming (MIP) formulations. The presented models cover many important practical side constraints from different technological contexts. In contrast to previous models from the literature, they can be used to design large two-layer networks with survivability requirements. We discuss modeling alternatives for various aspects of a multi-layer network and compare different routing formulations under multi-layer survivability constraints. We solve our models using a branch-and-cut-and-price approach with various problemspecific enhancements. This includes a presolving technique based on linear programming to reduce the problem size, combinatorial and sub-MIP-based primal heuristics to compute feasible network configurations, cutting planes which take the multi-layer survivability constraints into account to improve the lower bound on the optimal network cost, and column generation to generate flow variables dynamically during the algorithm. We develop techniques to speed up computations in a Benders decomposition approach and compare this approach to the standard formulation with a single MIP. We use the developed techniques to design large survivable two-layer networks by means of linear and integer programming methods. On realistic test instances with up to 67 network nodes and survivability constraints, we investigate the algorithmic impact of our techniques and show how to use them to compute good network configurations with quality guarantees. Most of the smaller test instances with up to 17 nodes can be solved to near-optimality. Moreover, we can compute feasible solutions and dual bounds even for large networks with survivability constraints, which has not been possible before.
    Keywords: ddc:510
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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    On the Factorization of Simplex Basis Matrices (2009)
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    Publication Date: 2020-08-05
    Description: In the simplex algorithm, solving linear systems with the basis matrix and its transpose accounts for a large part of the total computation time. We investigate various methods from modern numerical linear algebra to improve the computation speed of the basis updates arising in LPs. The experiments are executed on a large real-world test set. The most widely used solution technique is sparse LU factorization, paired with an updating scheme that allows to use the factors over several iterations. Clearly, small number of fill-in elements in the LU factors is critical for the overall performance. Using a wide range of LPs we show numerically that after a simple permutation the non-triangular part of the basis matrix is so small, that the whole matrix can be factorized with (relative) fill-in close to the optimum. This permutation has been exploited by simplex practitioners for many years. But to our knowledge no systematic numerical study has been published that demonstrates the effective reduction to a surprisingly small non-triangular problem, even for large scale LPs. For the factorization of the non-triangular part most existing simplex codes use some variant of dynamic Markowitz pivoting, which originated in the late 1950s. We also show numerically that, in terms of fill-in and in the simplex context, dynamic Markowitz is quite consistently superior to other, more recently developed techniques.
    Keywords: ddc:510
    Language: English
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    Computing expectation values for molecular quantum dynamics (2009)
    Details
    Publication Date: 2020-03-11
    Description: We compute expectation values for the solution of the nuclear Schrödinger equation. The proposed particle method consists of three steps: sampling of the initial Wigner function, classical transport of the sampling points, weighted phase space summation for the final computation of the expectation values. The Egorov theorem guarantees that the algorithm is second order accurate with respect to the semiclassical parameter. We present numerical experiments for a two-dimensional torsional potential with three different sets of initial data and for a six-dimensional Henon-Heiles potential. By construction, the computing times scale linearly with the number of initial sampling points and range between three seconds and one hour.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 35
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    Extending a CIP framework to solve MIQCPs (2009)
    Details
    Publication Date: 2022-03-14
    Description: This paper discusses how to build a solver for mixed integer quadratically constrained programs (MIQCPs) by extending a framework for constraint integer programming (CIP). The advantage of this approach is that we can utilize the full power of advanced MIP and CP technologies. In particular, this addresses the linear relaxation and the discrete components of the problem. For relaxation, we use an outer approximation generated by linearization of convex constraints and linear underestimation of nonconvex constraints. Further, we give an overview of the reformulation, separation, and propagation techniques that are used to handle the quadratic constraints efficiently. We implemented these methods in the branch-cut-and-price framework SCIP. Computational experiments indicates the potential of the approach.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 36
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    A Subspace Approach to Molecular Markov State Models via an Infinitesimal Generator (2009)
    Details
    Publication Date: 2016-06-09
    Description: Supercomputers can simulate complex molecular systems. However, there is a very large gap between the fastest oscillations of covalent bonds of a molecule and the time-scale of the dominant processes. In order to extract the dominant time-scales and to identify the dominant processes, a clustering of information is needed. This thesis shows that only the subspace-based Robust Perron Cluster Analysis (PCCA+) can solve this problem correctly by the construction of a Markov State Model. PCCA+ allows for time-extrapolation in molecular kinetics. This thesis shows the difference between molecular dynamics and molecular kinetics. Only in the molecular kinetics framework a definition of transition rates is possible. In this context, the existence of an infinitesimal generator of the dynamical processes is discussed. If the existence is assumed, the Theorem of Gauß can be applied in order to compute transition rates efficiently. Molecular dynamics, however, is not able to provide a suitable statistical basis for the determination of the transition pattern.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 37
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    Enhanced Paxos Commit for Transactions on DHTs (2009)
    Details
    Publication Date: 2021-01-22
    Description: Key/value stores which are built on structured overlay networks often lack support for atomic transactions and strong data consistency among replicas. This is unfortunate, because consistency guarantees and transactions would allow a wide range of additional application domains to benefit from the inherent scalability and fault-tolerance of DHTs. The Scalaris key/value store supports strong data consistency and atomic transactions. It uses an enhanced Paxos Commit protocol with only four communication steps rather than six. This improvement was possible by exploiting information from the replica distribution in the DHT. Scalaris enables implementation of more reliable and scalable infrastructure for collaborative Web services that require strong consistency and atomic changes across multiple items.
    Keywords: ddc:004
    Language: English
    Type: reportzib , doc-type:preprint
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  • 38
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    Approximations for the second moments of sojourn times in M/GI systems under state-dependent processor sharing (2009)
    Details
    Publication Date: 2020-08-05
    Description: We consider a system with Poisson arrivals and general service times, where the requests are served according to the State-Dependent Processor Sharing (SDPS) discipline (Cohen's generalized processor sharing discipline), where each request receives a service capacity which depends on the actual number of requests in the system. For this system, denoted by $M/GI/SDPS$, we derive approximations for the squared coefficients of variation of the conditional sojourn time of a request given its service time and of the unconditional sojourn time by means of two-moment fittings of the service times. The approximations are given in terms of the squared coefficients of variation of the conditional and unconditional sojourn time in related $M/D/SDPS$ and $M/M/SDPS$ systems, respectively. The numerical results presented for $M/GI/m-PS$ systems illustrate that the proposed approximations work well.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 39
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    Zum Nutzen des Web 2.0 für „Die kleine Kollaboration“ in den Wissenschaften (2009)
    Details
    Publication Date: 2020-12-11
    Description: Gemeinsame Web-Auftritte zu organisieren, die sich über mehrere Institutionen und Fachgebiete erstrecken, ist eine anspruchsvolle und faszinierende Aufgabe, die auf verschiedene Weise gelingen, aber auch scheitern kann. Wer sich daran versucht, tut gut daran, sich über bestimmte Prinzipien und technische Mittel zu informieren, die das fortgeschrittene Web ihm heute bietet. Das Internet, das World Wide Web und das moderne Web 2.0 sind in einer fast zwanzig Jahre dauernden Kollaboration einer globalen Gemeinschaft von Entwicklern und Anwendern entstanden. Es enthält heute eine Fülle sofort einsetzbarer Komponenten, von der „Benutzerdefinierten Google-Suche Beta“ mit Google‘s PageRanking auf ausgewählten Web-Seiten bis hin zum automatisierten Web-Server mit Content-Management für das „Mitmach-Web“. Der Artikel stellt nur eine kleine Auswahl solcher Lösungen vor und macht den Versuch, einige Prinzipien des Web 2.0 so herauszuarbeiten, dass die notwendige Kommunikation zwischen Managern, Technikern, Redakteuren und Organisatoren in der kleinen Kollaboration unterstützt wird. „Kleine Kollaboration“ bedeutet hier, dass es nicht um die globale Vernetzung von technischen Großgeräten der e-Science gehen soll, auch nicht um die Super-Suchmaschine in Europa, sondern um die Unterstützung der Zusammenarbeit und Kommunikation von Wissenschaftlern und Museumsfachleuten mit Ihren Nutzern.
    Keywords: ddc:020
    Language: German
    Type: reportzib , doc-type:preprint
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  • 40
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    Insensitivity bounds for the moments of the sojourn times in M/GI systems under state-dependent processor sharing (2009)
    Details
    Publication Date: 2020-08-05
    Description: We consider a system with Poisson arrivals and i.i.d. service times and where the requests are served according to the state-dependent (Cohen's generalized) processor sharing discipline, where each request in the system receives a service capacity which depends on the actual number of requests in the system. For this system we derive asymptotically tight upper bounds for the moments of the conditional sojourn time of a request with given required service time. The bounds generalize corresponding results, recently given for the single-server processor sharing system by Cheung et al. and for the state-dependent processor sharing system with exponential service times by the authors. Analogous results hold for the waiting times.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 41
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    Randomized Online Algorithms for Dynamic Multi-Period Routing Problems (2009)
    Details
    Publication Date: 2020-11-13
    Description: The Dynamic Multi-Period Routing Problem DMPRP introduced by Angelelli et al. gives a model for a two-stage online-offline routing problem. At the beginning of each time period a set of customers becomes known. The customers need to be served either in the current time period or in the following. Postponed customers have to be served in the next time period. The decision whether to postpone a customer has to be done online. At the end of each time period, an optimal tour for the customers assigned to this period has to be computed and this computation can be done offline. The objective of the problem is to minimize the distance traveled over all planning periods assuming optimal routes for the customers selected in each period. We provide the first randomized online algorithms for the DMPRP which beat the known lower bounds for deterministic algorithms. For the special case of two planning periods we provide lower bounds on the competitive ratio of any randomized online algorithm against the oblivious adversary. We identify a randomized algorithm that achieves the optimal competitive ratio of $\frac{1+\sqrt{2}}{2}$ for two time periods on the real line. For three time periods, we give a randomized algorithm that is strictly better than any deterministic algorithm.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 42
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    Constraint Integer Programming (2009)
    Details
    Publication Date: 2021-08-05
    Description: This thesis introduces the novel paradigm of "constraint integer programming" (CIP), which integrates constraint programming (CP) and mixed integer programming (MIP) modeling and solving techniques. It is supplemented by the software SCIP, which is a solver and framework for constraint integer programming that also features SAT solving techniques. SCIP is freely available in source code for academic and non-commercial purposes. Our constraint integer programming approach is a generalization of MIP that allows for the inclusion of arbitrary constraints, as long as they turn into linear constraints on the continuous variables after all integer variables have been fixed. The constraints, may they be linear or more complex, are treated by any combination of CP and MIP techniques: the propagation of the domains by constraint specific algorithms, the generation of a linear relaxation and its solving by LP methods, and the strengthening of the LP by cutting plane separation. The current version of SCIP comes with all of the necessary components to solve mixed integer programs. In the thesis, we cover most of these ingredients and present extensive computational results to compare different variants for the individual building blocks of a MIP solver. We focus on the algorithms and their impact on the overall performance of the solver. In addition to mixed integer programming, the thesis deals with chip design verification, which is an important topic of electronic design automation. Chip manufacturers have to make sure that the logic design of a circuit conforms to the specification of the chip. Otherwise, the chip would show an erroneous behavior that may cause failures in the device where it is employed. An important subproblem of chip design verification is the property checking problem, which is to verify whether a circuit satisfies a specified property. We show how this problem can be modeled as constraint integer program and provide a number of problem-specific algorithms that exploit the structure of the individual constraints and the circuit as a whole. Another set of extensive computational benchmarks compares our CIP approach to the current state-of-the-art SAT methodology and documents the success of our method.
    Description: Diese Arbeit stellt einen integrierten Ansatz aus "Constraint Programming" (CP) und Gemischt-Ganzzahliger Programmierung ("Mixed Integer Programming", MIP) vor, den wir "Constraint Integer Programming" (CIP) nennen. Sowohl Modellierungs- als auch Lösungstechniken beider Felder fließen in den neuen integrierten Ansatz ein, um die unterschiedlichen Stärken der beiden Gebiete zu kombinieren. Als weiteren Beitrag stellen wir der wissenschaftlichen Gemeinschaft die Software SCIP zur Verfügung, die ein Framework für Constraint Integer Programming darstellt und zusätzlich Techniken des SAT-Lösens beinhaltet. SCIP ist im Source Code für akademische und nicht-kommerzielle Zwecke frei erhältlich. Unser Ansatz des Constraint Integer Programming ist eine Verallgemeinerung von MIP, die zusätzlich die Verwendung beliebiger Constraints erlaubt, solange sich diese durch lineare Bedingungen ausdrücken lassen falls alle ganzzahligen Variablen auf feste Werte eingestellt sind. Die Constraints werden von einer beliebigen Kombination aus CP- und MIP-Techniken behandelt. Dies beinhaltet insbesondere die "Domain Propagation", die Relaxierung der Constraints durch lineare Ungleichungen, sowie die Verstärkung der Relaxierung durch dynamisch generierte Schnittebenen. Die derzeitige Version von SCIP enthält alle Komponenten, die für das effiziente Lösen von Gemischt-Ganzzahligen Programmen benötigt werden. Die vorliegende Arbeit liefert eine ausführliche Beschreibung dieser Komponenten und bewertet verschiedene Varianten in Hinblick auf ihren Einfluß auf das Gesamt-Lösungsverhalten anhand von aufwendigen praktischen Experimenten. Dabei wird besonders auf die algorithmischen Aspekte eingegangen. Ein weiterer Hauptteil der Arbeit befasst sich mit der Chip-Design-Verifikation, die ein wichtiges Thema innerhalb des Fachgebiets der "Electronic Design Automation" darstellt. Chip-Hersteller müssen sicherstellen, dass der logische Entwurf einer Schaltung der gegebenen Spezifikation entspricht. Andernfalls würde der Chip fehlerhaftes Verhalten aufweisen, dass zu Fehlfunktionen innerhalb des Gerätes führen kann, in dem der Chip verwendet wird. Ein wichtiges Teilproblem in diesem Feld ist das Eigenschafts-Verifikations-Problem, bei dem geprüft wird, ob der gegebene Schaltkreisentwurf eine gewünschte Eigenschaft aufweist. Wir zeigen, wie dieses Problem als Constraint Integer Program modelliert werden kann und geben eine Reihe von problemspezifischen Algorithmen an, die die Struktur der einzelnen Constraints und der Gesamtschaltung ausnutzen. Testrechnungen auf Industrie-Beispielen vergleichen unseren Ansatz mit den bisher verwendeten SAT-Techniken und belegen den Erfolg unserer Methode.
    Keywords: ddc:510
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 43
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    Fare Planning for Public Transport (2009)
    Details
    Publication Date: 2020-08-05
    Description: In this paper we investigate the fare planning model for public transport, which consists in designing a system of fares maximizing the revenue. We discuss a discrete choice model in which passengers choose between different travel alternatives to express the demand as a function of fares. Furthermore, we give a computational example for the city of Potsdam and discuss some theoretical aspects.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 44
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    Improving the performance of elevator systems using exact reoptimization algorithms (2009)
    Details
    Publication Date: 2020-08-05
    Description: This extended abstract is about algorithms for controlling elevator systems employing destination hall calls, i.e. the passenger provides his destination floor when calling an elevator. We present the first exact algorithm for controlling a group of elevators and report on simulation results indicating that destination hall call systems outperform conventional systems.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 45
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    On goal-oriented adaptivity for elliptic optimal control problems (2009)
    Details
    Publication Date: 2019-01-29
    Description: The paper proposes goal-oriented error estimation and mesh refinement for optimal control problems with elliptic PDE constraints using the value of the reduced cost functional as quantity of interest. Error representation, hierarchical error estimators, and greedy-style error indicators are derived and compared to their counterparts when using the all-at-once cost functional as quantity of interest. Finally, the efficiency of the error estimator and generated meshes are demonstrated on numerical examples.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 46
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    Consistency Results for the Contact-Stabilized Newmark Method (2009)
    Details
    Publication Date: 2016-06-09
    Description: The paper considers the time integration of frictionless dynamical contact problems between viscoelastic bodies in the frame of the Signorini condition. Among the numerical integrators, interest focuses on the contact-stabilized Newmark method recently suggested by Deuflhard et al., which is compared to the classical Newmark method and an improved energy dissipative version due to Kane et al. In the absence of contact, any such variant is equivalent to the Störmer-Verlet scheme, which is well-known to have consistency order 2. In the presence of contact, however, the classical approach to discretization errors would not show consistency at all because of the discontinuity at the contact. Surprisingly, the question of consistency in the constrained situation has not been solved yet. The present paper fills this gap by means of a novel proof technique using specific norms based on earlier perturbation results due to the authors. The corresponding estimation of the local discretization error requires the bounded total variation of the solution. The results have consequences for the construction of an adaptive timestep control, which will be worked out subsequently in a forthcoming paper.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 47
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    Discrete Optimization in Public Transportation (2009)
    Details
    Publication Date: 2020-08-05
    Description: The mathematical treatment of planning problems in public transit has made significant advances in the last decade. Among others, the classical problems of vehicle and crew scheduling can nowadays be solved on a routine basis using combinatorial optimization methods. This is not yet the case for problems that pertain to the design of public transit networks, and for the problems of operations control that address the implementation of a schedule in the presence of disturbances. The article gives a sketch of the state and important developments in these areas, and it addresses important challenges. The vision is that mathematical tools of computer aided scheduling (CAS) will soon play a similar role in the design and operation of public transport systems as CAD systems in manufacturing.
    Description: Die mathematische Behandlung von Planungsproblemen im öffentlichen Verkehr hat im letzten Jahrzehnt große Fortschritte gemacht. Klassische Probleme wie die Umlauf- und die Dienstplanung können heutzutage routinemäßig mit kombinatorischen Optimierungsmethoden gelöst werden. Die Behandlung von Problemen der Angebotsplanung und der Betriebssteuerung sind dagegen noch nicht ganz auf diesem Stand. Dieser Artikel gibt einen Überblick über den Stand der Forschung, über wichtige Entwicklungen und einige Herausforderungen in diesem Gebiet. Die Vision ist, dass mathematische Planungswerkzeuge im öffentlichen Verkehr (Computer Aided Scheduling, CAS) in Zukunft eine ähnliche Rolle spielen werden wie CAD-Systeme in der industriellen Fertigung.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 48
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    Variational and statistical shape modeling for 3D geometry reconstruction (2009)
    Details
    Publication Date: 2022-07-19
    Description: The reconstruction of geometric shapes plays an important role in many biomedical applications. One example is the patient-specific, computer-aided planning of complex interventions, which requires the generation of explicitly represented geometric models of anatomical structures from medical image data. Only solutions that require minimal interaction by medical personnel are likely to enter clinical routine. Another example is the planning of surgical corrections of deformities where the target shape is unknown. Surgeons are often forced to resort to subjective criteria. These applications still pose highly challenging reconstruction problems, which are addressed in this thesis. The fundamental hypothesis, pursued in this thesis, is that the problems can be solved by incorporating a-priori knowledge about shape and other application-specific characteristics. Here, we focus mainly on the aspect of geometric shape analysis. The basic idea is to capture the most essential variations of a certain class of geometric objects via statistical shape models, which model typical features contained in a given population, and restrict the outcome of a reconstruction algorithm (more or less) to the space spanned by such models. A fundamental prerequisite for performing statistical shape analysis on a set of different objects is the identification of corresponding points on their associated surfaces. This problem is particularly difficult to solve if the shapes stem from different individuals. The reason lies in the basic difficulty of defining suitable measures of similarity. In this thesis, we divide the correspondence problem into feature and non-feature matching. The feature part depends on the application, while the non-feature part can be characterized by a purely geometric description. We propose two different approaches. The first approach has proved useful in many applications. Yet, it suffers from some practical limitations and does not yield a measure of similarity. Our second, variational, approach is designed to overcome these limitations. In it, we propose to minimize an invariant stretching measure, constrained by previously computed features. An important property, which sets our method apart from previous work, is that it does not require the computation of a global surface parameterization.
    Keywords: ddc:510
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 49
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    Generierung hybrider Gitter für die Strömungssimulation auf komplexen anatomischen Geometrien (2009)
    Details
    Publication Date: 2022-07-19
    Description: Basierend auf einem vorhandenen Ansatz zur Einführung von anisotropen Tetraedern im Randbereich eines reinen Tetraedergitters wird ein Gittergenerator für hybride Gitter implementiert. Das hybride Gitter besteht in Randnähe primär aus anisotropen Prismen und im Inneren der Geometrie aus isotropen Tetraedern. Eine erhöhte Auflösung im Randbereich soll zu besseren Ergebnissen von numerischen Strömungssimulationen führen, für welche eine problemangepasste Diskretisierung des zu untersuchenden Gebietes benötigt wird. In dem zuvor genannten Ansatz wird eine Reihe von Übergangselementen vorgeschlagen, die an scharfen Kanten der Oberfläche platziert werden sollen. Im Rahmen dieser Diplomarbeit wird die Idee der Übergangselemente aufgegriffen und bei hybriden Gittern eingesetzt, um auch komplexe Eingabegeometrien vergittern zu können. Der ursprüngliche Gittergenerierungprozess wird überarbeitet und erweitert. Eine neue Menge an Übergangselementen wird eingeführt, es werden gekrümmte Extrusionsvektoren verwendet und es wird die Auswertung der medialen Oberfläche vorgenommen, um Überschneidungen im hybriden Gitter zu vermeiden. Der Gittergenerator wird als Modul in das Visualisierungs- und Analyseprogramm Amira implementiert und die erstellten hybriden Gitter werden auf ihre Elementqualität und die Güte der Strömungssimulationsergebnisse hin überprüft.
    Description: Based on an existing approach for the introduction of anisotropic tetrahedra near the surface boundary of a tetrahedral grid a grid generator for hybrid grids is implemented. The hybrid grid consists near the surface boundary primarily of anisotropic prisms and inside the geometry of isotropic tetrahedra. An increased resolution near the boundary should lead to better results of numerical flow simulations, which needs a problem specific discretization of the analyzed domain. In the aforementioned approach a set of transition elements is suggested, which should be placed at sharp surface corners. As a part of this diploma thesis the concept of using transition elements is applied for creating hybrid grids even for very complex input geometries. The initial grid generation process is revised and enhanced. A new set of transition elements is introduced, curved extrusion vectors are used and the medial surface is evaluated to avoid intersections in the hybrid grid. The grid generator is implemented as a module for the visualization and analysis tool Amira and the element quality of the generated hybrid grids and the quality of flow simulations performed on the grids are tested.
    Keywords: ddc:004
    Language: German
    Type: masterthesis , doc-type:masterThesis
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  • 50
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    Automatisierte Fernleihe im KOBV - Handbuch für Bibliotheken - 3. Auflage (2009)
    Details
    Publication Date: 2024-01-12
    Description: Im Kooperativen Bibliotheksverbund Berlin-Brandenburg (KOBV) wird für die automatisierte Fernleihe der Zentrale-Fernleihserver (ZFL-Server) der Firma Sisis eingesetzt. Die Software ist in der KOBV-Zentrale installiert. Der ZFL-Server dient im KOBV sowohl für die Bestellung von Monographien als auch für die Bestellung von Aufsatzkopien aus Zeitschriften. Prinzipiell gibt es zwei Verfahren, mit denen sich Bibliotheken an der automatisierten Fernleihe beteiligen können: das E-Mail-Verfahren und das SLNP-Verfahren. Auf beide wird im Handbuch eingegangen. Die automatisierte Fernleihe wurde im KOBV eingeführt, um die Fernleihe für die Benutzer zu beschleunigen, das Verfahren für die Bibliotheksmitarbeiter zu vereinfachen und den Arbeitsaufwand zu reduzieren. Sie basiert darauf, dass eine Bestellung anhand eines gefundenen Treffers ausgelöst wird – d.h. die bibliographischen Daten sind bereits verifiziert und in einem Katalog nachgewiesen. Anschließend wird die Bestellung über den ZFL-Server automatisch ausgeführt und verwaltet – sowohl in der regionalen KOBV-Fernleihe als auch in der verbundübergreifenden Fernleihe mit den deutschen Bibliotheksverbünden. Der ZFL-Server besteht aus verschiedenen technischen Komponenten. Eine dieser Komponenten ist das Bibliothekskonto, eine Internetanwendung, in der die Bestellverwaltung des ZFL-Servers für die Bibliotheksbediensteten transparent abläuft. Dazu hat jede Bibliothek im Bibliothekskonto eine eigene, Passwort-geschützte Dienstoberfläche. Im Laufe des Jahres 2009 hat die KOBV-Zentrale das Bibliothekskonto grundlegend überarbeitet; die neue Version wurde im September 2009 freigegeben. Neben der Überabeitung des Interfaces – so wird den Bibliotheken auf der Startseite nun eine Übersicht ihrer laufenden Bestellungen angezeigt und dient als direkter Einstieg in die Bearbeitung – wurde das Bibliothekskonto um folgende Funktionen erweitert: Bestellung zurücklegen (HOLD), Vormerkungen, Bestellungen zur Anfrage, Abbruch des Leitweges (auch verbundübergreifend), erweiterte Kommentarfunktion, Bestellnummernsuche in allen Verbünden. Das Handbuch, das die Vorgänge der Bestellverwaltung im Bibliothekskonto beschreibt, wurde in der nun vorliegenden 3. Auflage um die Beschreibung der neuen Funktionen ergänzt. An dieser Stelle ein Dank an die Kolleginnen und Kollegen aus den KOBV-Bibliotheken – Frau Bruske (UB der Freien Universität Berlin), Frau Ebert (UB der Europa-Universität Viadrina Frankfurt (Oder)), Frau Preuß (UB der Technischen Universität Berlin) und Herrn Ringmayer (Zentral- und Landesbibliothek Berlin) – für die tatkräftige Unterstützung bei der Entwicklung der neuen Funktionen.
    Keywords: ddc:020
    Language: German
    Type: reportzib , doc-type:preprint
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  • 51
    Electronic Resource
    Electronic Resource
    Bicyclo[2.1.1]hexane aus Tricyclo[3.1.0.02,6]hexanen (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 2012-2021 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Bicyclo[2.1.1]hexanes from Tricyclo[3.1.0.02,6]hexanesThe novel tricyclo[3.1.0.02,6]hexane derivatives 3 and 4, being fused with a fife- and a sixmembered ring respectively, are prepared from benzvalene in several steps. They and their lower homologues 1 and 2, having a three- and fourmembered ring respectively, add thiophenol under conditions of a radical reaction to form smoothly one cyclobutylphenyl thioether (16-19) in each case. Therefrom the parent hydrocarbons (5-8) which contain the bicyclo[2.1.1]hexane skeleton, are obtained by means of reduction with lithium in ethylamine.
    Notes: Ausgehend von Benzvalen werden in mehreren Stufen die neuen Tricyclo[3.1.0.02,6]hexan-Derivate 3 und 4 mit anelliertem Fünf- bzw. Sechsring dargestellt. Sie und ihre niedrigeren Homologen 1 und 2 mit Drei- bzw. Vierring nehmen unter Bedingungen einer Radikalreaktion Thiophenol auf, wobei glatt jeweils ein Cyclobutylphenylthioether (16-19) gebildet wird. Mit Lithium in Ethylamin sind aus 16-19 die tricyclischen Stammkohlenwasserstoffe mit dem Bicyclo[2.1.1 ]hexan-Gerüst (5-8) erhältlich.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120611
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  • 52
    Electronic Resource
    Electronic Resource
    Der Einfluß anellierter Ringe auf die 13C-NMR-chemischen Verschiebungen von Tricyclo[3.1.0.02,6]hexan- und Bicyclo[2.1.1]hexan-Derivaten (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 2022-2027 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Influence of Fused Rings on the 13C Shieldings of Tricyclo[3.1.0.02,6]hexane and Bicyclo[2.1.1]hexane DerivativesThe 13C shieldings of the tricyclo[3.1.0.02,6]hexane derivatives 2-5 and of the bicyclo[2.1.1]-hexane derivatives 7-10 and 12-15 show a strong dependence on the size of the fused rings. Especially the γ-anti-effects, which cause downfield shifts, and the γ-syn-effects of these rings, which result in upfield shifts, are subject to unexpected variations.
    Notes: Die 13C-chemischen Verschiebungen der Tricyclo[3.1.0.02,6]hexan-Derivate 2-5 und der Bicyclo[2.1.1]hexan-Derivate 7-10 und 12-15 zeigen eine starke Abhängigkeit von der Größe der anellierten Ringe. Insbesondere die nach tieferem Feld gerichteten γ-anti-Effekte und die nach höherem Feld gerichteten γ-syn-Effekte dieser Ringe unterliegen unerwarteten Variationen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120612
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    Reaktionen an Indolderivaten, XXXIX. Stereoselektive Totalsynthese von Eburnamonin, Eburnamin und Eburnamenin (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1902-1912 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions with Indole Derivatives, XXXIX. A Stereoselective Synthesis of Eburnamonine, Eburnamine, and EburnamenineStudies on the five-membered lactams 1 and 2 disclose a stereoselective access to eburnamonin-19-one (22). This substance is easily transformed into eburnamonine (25), eburnamine (30), and eburnamenine.
    Notes: Das Studium der 5-Ring-Lactame 1 und 2 eröffnet einen stereoselektiven Zugang zum Eburnamonin-19-on (22). Diese Substanz läßt sich auf einfache Weise in die drei Alkaloide Eburnamonin (25), Eburnamin (30) und Ehurnamenin überführen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120541
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  • 54
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    En-Reaktionen mit Cyanthioformaniliden (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1916-1918 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ene Reactions with CyanothioformanilidesCyanothioformanilides 3 react with methylenecyclohexane (1) and β-pinene (2) in boiling toluene to yield the adducts 4 and 5, resp., according to the mechanistic scheme of an ene reaction.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120543
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    Masthead (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120601
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  • 56
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    Synthesis of new chiral hydrocarbons (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1919-1922 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthese von neuen chiralen KohlenwasserstoffenUnsymmetrisches Anheften einer aliphatischen (CH2)n-Brücke an ein an sich achirales aromatisches System führt zu starren chiralen Kohlenwasserstoffen des Typs 2; die Enantiomeren 2 a konnten mit Hilfe von TAPA angereichert werden. Die Racemisierungskinetik wurde polarimetrisch bestimmt: ΔG≠20 = 93.6 kJ · mol-1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120544
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  • 57
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    Pheromone, XXIV. Notiz zur Synthese der Sexuallockstoffe (Z)-7-Dodecenylacetat und (Z)-7-Tetradecenylacetat (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1923-1925 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pheromones, XXIV. Synthesis of the Sex Attractants (Z)-7-Dodecenyl Acetate and (Z)-7-Tetradecenyl Acetate(Z)-7-Dodecenyl acetate, the female sex pheromone of the Noctuid moth Trichoplusia ni, and (Z)-7-tetradecenyl acetate, the sex attractant of Amathes c-nigrum (Lepidoptera), are prepared by stereoselective Wittig olefination using the „silazide“ -technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120545
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  • 58
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    Dynamische NMR- Untersuchungen an (Di-tert-butylamino)arsanen und -stibanen (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1927-1933 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dynamic NMR Studies of (Di-tert-butylamino)arsanes and -stibanesThe reaction of LiN[C(CH3)3]2 with AsX3 (X = F → Br). (CH3)3CAsCl2 and SbCl3 yields the di-tert-butylamino)arsanes 1a-c, 2 and dichloro(di-tert-butylamino)stibane (1d). LiN(CR3)-(SiR3), R=CH3and 1a-c form 3. The El — N torsional barriers of these compounds (measured by temperature dependent 1H-NMR spectroscopy) are compared with those of the (diisopropylamino)arsanes 4. and other related compounds. The influence of the N and El ligands with respect to the El — N torsional barrier is discussed. Thermolysis of 3c affords the di-tert-butylaminyl radical.
    Notes: Durch Umsetzung von LiN[C(CH3)3]2 mit AsX3 (X = F → Br), (CH3)3CAsCl2 und SbCl3 erhält man die (Di-tert-butylamino)arsane 1a-c und 2 sowie Dichlor(di-tert-butylamino)stiban reagieren mit LiN(CR3)(SiR3), R=CH3 zu 3 weiter. Die durch temperaturabhängige 1 H-NMR-Messungen ermittelten El- N-Rotationsbarrieren dieser Verbindungen werden hinsichtlich des Ligandeneinflusses am N- El - Atom mit den (Diisopropylamino)arsanen 4. und verwandten Molekülen verglichen. 3c. ergibt bei der Thermolyse das Di-tert-butylaminyl-Radikal.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120602
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  • 59
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    Isocyanidkomplexe, I. Isocyanphosphane und -arsane als Komplexliganden (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1934-1940 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Isocyanide Complexes, I. Isocyanophosphanes and -arsanes as Ligands of ComplexesThe reaction of K[CpMn(CO)2CN] (Cp = η-C5H5) with PR2Cl (R=C2H5, OC2H5, C6H5) and As(C6H5)2Cl yields the complexes CpMn(CO)2CNPR2 (3a - c) and CpMn(CO)2CNAsPh2 (3d) with C-coordinated isocyanophosphanes and -arsanes. In the reaction of CpMn(CO)2CNPPh2 with CpMn(CO)2 THF or of K[CpMn(CO)2CN] with CpMn(CO)2PPh2Cl a complex with an isocyanophosphane bridge, {CpMn(CO)2}2(CNPPh2) (4), is obtained. The IR, NMR, and mass spectra of the compounds 3a-d and 4 are discussed.
    Notes: Bei der Umsetzung von K[CpMn(CO)2CN] (Cp = η-C5H5) mit PR2Cl (R=C2H5, OC2H5, C6H5) und As(C6H5)2Cl entstehen die Komplexe CpMn(CO)2CNPR2 (3 a - c) und CpMn(CO)2CNAsPh2 (3d) mit C-gebundenen Isocyanphosphanen und -arsanen. Durch Reaktion von CpMn(CO)2CNPPh2 (3c) mit CpMn(CO)2 THF bzw. von K[CpMn(CO)2]CN mit CpMn(CO)2PPh2Cl erhält man den Komplex {CpMn(CO)2}2(CNPPh2) (4) mit einer Isocyanphosphan-Brücke. Die IR-, NMR- und Massenspektren der Verbindungen 3a-d und 4 werden diskutiert.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120603
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    Barrieren der behinderten Rotation um die N-glycosidische Bindung, IV. 1-(β-D-Ribofuranosyl)isocyanursäuren (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1941-1947 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Barriers to Hindered Rotation Around the N-Glycosidic Bond, IV. 1-(βD-Ribofuranosyl) isocyanuric AcidsThe β-ribofuranosyl nucleosides 5a-c and 6b, c are synthesized. The temperature dependency of the 1H- and 13C-NMR spectra can only be interpreted as hindered rotation around the N-glycosidic bond2). The Gibbs activation energies (43-46 kJmol-1) are independent of acetylation of the OH groups of the furanose ring or restriction of its flexibility through formation of a 2′,3′-isopropylidene derivative, and are considerably lower than the corresponding data (about 69 kJmol-1) of the glucopyranosyl nucleosides 7b, c. The activation entropies are small. The results are interpreted.
    Notes: Es werden Synthesen der β-Ribofuranosylnucleoside 5a-c und 6b, c beschrieben. Die Temperaturabhängigkeiten der 1H-und 13C-NMR-Spektren lassen sich nur als Folge behinderter Rotation um die N-glycosidische Bindung deuten2) Die Gibbsschen Aktivierungsenergien (43-46 kJmol-1) sind unabhängig von einer Acetylierung der OH-Gruppen des Furanoseringes oder einer Einschränkung von dessen Flexibilität durch Bildung eines 2′,3′-Isopropylidenderivates und liegen erheblich tiefer als die entsprechenden Werte (um 69 kJmol-1) der Glucopyranosylnucleoside 7b, c. Die Aktivierungsentropien sind gering. Die Befunde werden gedeutet.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120604
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    Synthesen von α-Bromisothiocyanaten (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1948-1955 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of α-BromoisothiocyanatesSecondary isothiocyanates (1j-q) and primary isothiocyanates R—CH2 - NCS with an activating group R (1f, g) react with N-bromosuccinimide (NBS) to form α-bromoisothiocyanates 2 in high yields. The not activated primary isothiocyanate 1c slowly forms the stable α,α-dibromoisothiocyanate 10. In the presence of β-hydrogens some of the α-bromoisothiocyanates 2 eliminate HBr spontaneously, and secondary products may be formed. The α-bromination of isothiocyanates is a radical reaction following a Goldfinger mechanism.
    Notes: Sekundäre Isothiocyanate (1j-q) und primäre Isothiocyanate R-CH2 - NCS mit einer aktivierenden Gruppe R (1f, g) lassen sich mit N-Bromsuccinimid (NBS) in hohen Ausbeuten zu den α-Bromisothiocyanaten 2 bromieren. Das nicht aktivierte Isothiocyanat 1c reagiert langsam zum stabilen α,α-Dibromisothiocyanat 10. Bei Anwesenheit von β-Wasserstoffatomen spalten die α-Bromisothiocyanate 2 zum Teil spontan HBr ab, und es entstehen Folgeprodukte. Die α-Bromierung der Isothiocyanate erfolgt radikalisch nach einem Goldfinger-Mechanismus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120605
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    Reaktionen von α-Bromisothiocyanaten (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1956-1972 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of α-Bromoisothiocyanatesα-Bromoisothiocyanates 11.2) with a hydrogen in β-position eliminate HBr to form vinyl isothiocyanates (products 2, 3, 5). Water hydrolyzes 1 to carbonyl compounds (7a). Hard nucleophiles attack 1 at the α-C-atom with substitution of bromine (products 8-12), but soft nucleophiles add to the C-atom of the isothiocyanato group (products 14, 19). Compounds 1 react with bifunctional nucleophiles to heterocycles (e. g. products 16, 21). The chemical properties of the classes of compounds, part of which are new, e. g. the geminal diisothiocyanates 12, are examined. The alkylidene thiourea 14f shows hindered rotation around the amide-CS—N bond (ΔG≠394 = 82.8 kJmol-1) and around the C=N double bond (ΔG≠244 = 52.9 kJmol-1).
    Notes: α-Bromisothiocyanate 1 mit einem β-Wasserstoff spalten HBr zu Vinylisothiocyanaten ab (Produkte 2, 3, 5). Wasser hydrolysiert 1 zu Carbonylverbindungen (7a). Harte Nucleophile greifen 1 am α-C-Atom unter Substitution des Broms an (Produkte 8-12), weiche Nucleophile lagern sich dagegen an das C-Atom der Isothiocyanatgruppe an (Produkte 14, 19). Verbindungen 1 reagieren mit bifunktionellen Nucleophilen zu Heterocyclen (z. B. Produkte 16, 21). Die chemischen Eigenschaften der z. T. neuen Verbindungsklassen, z. B. der geminalen Diisothiocyanate 12, werden untersucht. Der Alkylidenthioharnstoff 14f zeigt behinderte Rotation um die Amid Cs—N-Bindung (ΔG≠394 = 82.8 kJmol-1) und um die C=N-Doppelbindung (ΔG≠244 = 52.9 kJmol-1).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120606
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    Die Kristallstruktur von (η3-Allyl)dicarbonyl(triphenyl-phosphan)cobalt und sein dynamisches Verhalten in Lösung (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1973-1980 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Crystal Structure and the Fluxional Behaviour in Solution of (η3-Allyl)dicarbonyl(triphenyl-phosphane)cobalt[Co(η3-C3H5)(CO)2PPh3] (1) crystallizes in the triclinic space group P1 with two molecules per unit cell. The crystal structure was solved and refined with X-ray diffraction data (R = 0.031, 2046 observed reflections). The cobalt atom has a distorted square pyramidal coordination with the formally bidentate η3-allyl ligand, the phosphane, and one carbonyl in the basal positions. According to the NMR spectra at temperatures down to 135 K, in solution there exists a fluxional equilibrium with the η3-allyl ligand oscillating between two enantiomeric positions.
    Notes: [Co(η3-C3H5)(CO)2PPh3] (1) kristallisiert triklin in der Raumgruppe P1 mit zwei Molekülen pro Elementarzelle. Die Kristallstruktur wurde mit Röntgenbeugungsdaten ermittelt und verfeinert (R = 0.031, 2046 beobachtete Reflexe). Das Cobaltatom ist verzerrt quadratisch-pyramidal koordiniert, mit dem formal zweizähnigen η3-Allylliganden, dem Phosphan und einem Carbonylliganden in der Pyramidenbasis. Nach den NMR-Spektren bei Temperaturen hinab bis 135 K liegt in Lösung ein dynamisches Gleichgewicht vor, bei dem die η3-Allylgruppe zwischen zwei enantiomeren Positionen fluktuiert.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120607
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    Hydrazidine, III. Synthese von 1,2,4,5-Tetrazino [3,2-a]isoindolen (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1981-1990 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hydrazidines, III. Synthesis of 1,2,4,5-Tetrazino[3,2-a]isoindolesReaction of acetohydrazide hydrazone hydrochloride (1) with phthalaldehydic acid (5) yields 3-methyl-1,10b-dihydro-1,2,4,5-tetrazino[3,2-a]isoindol-6(4H)-one (8), which affords 1,2,4,5-tetrazino[3,2-a]isoindol-6(4H)-one (9a) by mild oxidation. 9a is also obtained by the reaction of 1 with the phthalic acid derivatives 6a, 7a, and 7b. Starting with 9a, the 1,2,4,5-tetrazino[3,2-a]isoindoles 12-15 are synthesized. Interaction of 1 and 3-nitrophthalic anhydride (6b) yields two isomeric nitro-1,2,4,5-tetrazino[3,2-a]isoindol-6(4H)-ones (9b,c). Oxidation of 9a or b with KMnO4 in methanol affords the 1,2,4,5-tetrazino 17a, b. Mild Oxidation of 9a with KMnO4 in water/trichloromethane yields a dimer (20), which dissociates in nitromethane into the radical 19.
    Notes: Durch Reaktion von Acetohydrazid-hydrazon-hydrochlorid (1) mit Phthaladehydsäure (5) wird 3-Methyl-1, 10b-dihydro-1,2,4,5-tetrazino[3,2-a]isoindol-6(4H)-on (8) erhalten das durch milde Oxidation in 3-Methyl-1,2,4,5-tetrazino[3,2-a]isoindol-6(4H)-on (9a) übergeführt wird. 9a entsteht auch aus 1 und den Phthalsäurederivaten 6a, 7a und 7b. Ausgehend von 9a werden die 1,2,4,5-Tetrazino[3,2-a]isoindole 12-15 synthetisiert. Aus 1 und 3-Nitrophthalsäureanhydrid (6b) werden zwei isomere Nitro-1,2,4,5-tetrazino[3,2-a]isoindol-6(4H)-one (9b, c) erhalten. Oxidation von 9a oder b mit KMnO 4 in Methanol ergibt die 1,2,4,5-Tetrazine 17a, b. Vorsichtige Oxidation von 9a mit KmnO4 in Wasser/Chloroform ergibt ein Dimeres (20), das in Nitromethan in das Radikal 19 dissoziiert.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120608
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    Stereochemie der Metall-Metall-Bindung. Strukturvergleich der Komplexe Cr2(CO)8(AsMe2)2, CrFe(CO)7(AsMe2)2 und Fe2(CO)6(AsMe2)2 (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1991-1998 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereochemistry of the Metal-Metal Bond. Structural Comparison of the Complexes Cr2(CO)8(AsMe2)2, CrFe(CO)7(AsMe2)2, and Fe2(CO)6(AsMe2)2The molecular structures of the new complexes CFer2(CO)8(AsMe2)2 (1) and CrFe(CO)7(AsMe2)2 (2) were determined crystallographically, that of Fe2(CO)6(AsMe2)2 (3) was redetermined. In all three compounds the metal-metal bond lengths are determined by the goemetrical requirements of the ligands. The fact that the M2As2 framework is planar in 1 and strongly folded in 2 and 3 can also be explained by the steric demands of the ligands. Aspects of the fluxionality of these complexes are discussed.
    Notes: Die Molekülstrukturen der neuen Komplexe Cr2(CO)8(AsMe2)2 (1) und CrFe(CO)7(AsMe2)2 (2) wurden kristallographisch ermittelt, die von Fe2(CO)6(AsMe2)2 (3) wurde neu bestimmt. In allen drei Verbindungen sind die Metall-Metall-Bindungslängen durch die geometrischen Ansprüche der Liganden festgelegt. Auch die Tatsache, daß das M2As2-Gerüst in 1 eben und in 2 und 3 jeweils stark gefaltet ist, läßt sich auf den Raumbedarf der Liganden zurückführen. Aspekte der Fluktuation dieser Komplexe werden diskutiert.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120609
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    Untersuchungen an Stoffwechselprodukten von Mikroorganismen, XX. Die Konstitutionen der Pigmente vom Flexirubin-Typ aus Cytophaga johnsonae Cyjl (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1999-2011 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations on Metabolites of Microorganisms, XX. The Structures of the Flexirubin-type Pigments from Cytophaga johnsonae CyjlCytophaga johnsonae Cy jl produces more than 25 different flexirubin-type pigments (2 a-h, 3 a-h, 4 a-h, 5) besides lower concentrations of carotenoids. These pigments could be separated using HPLC. Their structures have been elucidated. 5 is the first known member in this class of bacterial pigments containing two chlorine atoms.
    Notes: Das Gleitende Bakterium Cytophaga johnsonae Cy jl produziert neben wenig Carotinoiden mehr als 25 verschiedene Pigmente vom Flexirubin-Typ (2a-h, 3a-h, 4a-h, 5), deren Trennung u.a. durch Hochdruckflüssigchromatographie gelang. Über die Konstitutionen dieser Pigmente wird berichtet. Mit 5 wurde erstmals in dieser Verbindungsklasse ein dichlorhaltiges Pigment aufgefunden.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120610
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    Proton Magnetic Resonance Investigation of Inversion at Tervalent Nitrogen, 6. Preparative Separations of Enantiomeric Diaziridines by Liquid Chromatography on Triacetylcellulose. Racemizations Monitored by Polarimetry and by 1H NMR (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 2028-2038 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Protonenresonanz-Untersuchugen zur Inversion am dreibindigen Stickstoffatom, 6. Präparative Trennungen enantiomerer Diaziridine durch Flüssigkeits-Chromatographie an Triacetylcellulose. Verfolgung der Racemisierungen mittels Polarimetrie und 1H-NMREnantiomere Diaziridine ließen sich durch Chromatographie an Triacetylcellulose anreichern. (-)-2, (+)-4 und (-)-4 wurden fast rein erhalten, wobei die enantiomeren Reinheiten (Tab. 1) mittels 1H-NMR in Gegenwart optisch aktiver Zusätze bestimmt wurden. Dasselbe Verfahren wurde im Hinblick auf die Verfolgung von Racemisierungen (Tab.2) erprobt, welche mit höherer Genauigkeit außerdem mittels Polarimetrie studiert wurden. Die Schwellen der Stickstoff-Inversion, welche die trans-Diaziridine 2 und 4 in cis-Zwischenstufen überführt, werden mit bekannten ΔG≠-Werten verglichen.
    Notes: Enantiomeric diaziridines have been partially separated by chromatography on triacetlycellulose. (-)-2, (+)-4, and (-)-4 were obtained almost pure, enantiomeric purities (Table 1) being measured by 1H NMR in the presence of optically active additives. The same procedure was tested for monitoring racemizations (Table 2) which were also studied, with higher accuracy, by polarimetry. The barriers to nitrogen inversion, converting the trans-diaziridines 2and4into cis-intermediates, are compared with known ΔG≠ values.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120613
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    Darstellung, Schwingungsspektrum und Kristallstruktur des dimeren (Isopropylidenamino) dimethylindiums (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 2039-2044 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation, Vibrational Spectrum, and Crystal Structure of Dimeric (Isopropylideneamino) dimethylindiumThe title compound [Me2C=N—InMe2]2 was prepared from N-chloro-2-propanimine and trimethylindium. Its IR and Raman spectra were assigned; together with the 1H-NMR spectrum and the mass spectrum a centrosymmetric molecular structure with a four-membered (InN)2 ring was deduced. This was confirmed by an X-ray structure determination, according to which there exist two dimeric molecules per unit cell in the space group P21/c. The structure was refined with 958 reflexions up to a residual index of R = 0.024.
    Notes: Die Titelverbindung [Me2C=N-InMe2]2 wurde aus N-Chlor-2-propanimin und Trimethylindium synthetisiert. Das IR-und Raman-Spektrum wurde zugeordnet; zusammen mit dem 1H-NMR- und dem Massenspektrum ergibt sich eine zentrosymmetrische Molekülstruktur mit einem (InN)2-Vierring. Dies wird durch die Röntgenstrukturbestimmung bestätigt, nach der eine Struktur mit zwei dimeren Molekülen pro Elementarzelle in der Raumgruppe P21/c vorliegt. Die Struktur wurde bis zu einem Übereinstimmungsindex von R = 0.024 für 958 Reflexe verfeinert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120614
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  • 69
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    Trimethylsilylcyanid als Umpolungsreagens, I. Nucleophile Acylierung von Alkylierungsmitteln mit aromatischen und heteroaromatischen Aldehyden (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 2045-2061 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Trimethylsilyl Cyanide  -  A Reagent for Umpolung, I. Nucleophilic Acylation of Alkylating Reagents with Aromatic and Heteroaromatic AldehydesThe readily accessible adducts 7 from (hetero)aromatic aldehydes and trimethylsilyl cyanide are deprotonated by lithium diisopropylamide. The so formed anions 8 react with alkyl halides, dialkyl sulfates and alkyl tosylates producing 19 with inversion and without interfering elimination. From 19 the protective group is removed under mild conditions and ketones 20 are produced mostly in 80-90% yield. The scope of the reaction sequence with respect to (hetero)aromatic aldehydes and alkylating agents is demonstrated. Lithium ions are shown to cooperate in the smooth substitution of tert-butyl iodide by 8. Within the given limits the described reaction sequence complements advantageously the known methods of nucleophilic acylation.
    Notes: Die aus (hetero)aromatischen Aldehyden und Trimethylsilylcyanid glatt zugänglichen Addukte 7 werden von Lithium-diisopropylamid zu den Anionen 8 deprotoniert, die ohne störende Eliminierung mit Alkylhalogeniden, Dialkylsulfaten und Alkyltosylaten unter Inversion zu 19 reagieren. Entfernung der Schutzgruppe aus 19 unter sehr milden Bedingungen liefert die Ketone 20 meist in Ausbeuten von 80-90%. Die Anwendungsbreite hinsichtlich der (hetero)aromatischen Aldehyde und der Alkylierungsmittel wird demonstriert. Für die glatte Substitution von tert-Butyliodid durch 8 wird Mitwirkung der Lithium-Ionen nachgewiesen. Im gesteckten Rahmen ergänzt diese nucleophile Acylierung die bekannten Methoden vorteilhaft.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120615
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    Trimethylsilylcyanid als Umpolungsreagens, II. Nucleophile Acylierung von Aldehyden und Ketonen unter anionischer 1,4-O,O-Silylgruppenwanderung (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 2062-2067 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Trimethylsilyl Cyanide  -  A Reagent for Umpolung, II. Nucleophilic Acylation of Aldehydes and Ketones with Anionic 1,4-O,O-Silyl ShiftThe anion 9, derived from O-(trimethylsilyl) benzaldehyde-cyanohydrin (8), adds quantitatively to aldehydes and ketones. The primary adduct 11, which can be trapped as 12 after short reaction times, rearranges with 1,4-0,0-silyl shift. By subsequent cyanide elimination acyloin silyl ethers 14 are formed. Hydrolysis of 14 yields 80-90% of acyloins 15.
    Notes: Das Anion 9 des O-(Trimethylsilyl)benzaldehyd-cyanhydrins (8) addiert sich quantitativ an Aldehyde und Ketone. Das Primäraddukt 11, nach kurzer Reaktionszeit als 12 faßbar, lagert sich unter 1,4-0,0-Silylgruppenwanderung und Cyanidabspaltung zu den Acyloin - trimethylsilylethern 14 um, aus denen durch Hydrolyse die Acyloine 15 mit 80-90% Ausbeute entstehen.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120616
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  • 71
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    Zweifache Deprotonierung von 2-Aryl-1-nitroethanen Umpolung der Nitroolefin-Reaktivität (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 234-248 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Double Deprotonation of 2-Aryl-1-nitroethanes.  -  Umpolung of the Nitroolefin Reactivityβ-Arylnitroethanes 4 are doubly deprotonated to the dilithio derivatives 6 when treated with two equivalents of n-butyllithium in HMPTA-containing THF at -80 to -90°C. The reagents (6) may be considered as the products (see 3 and 16b) of reduction of ω-nitrostyrenes 2, They react with haloalkanes (→ 7), aldehydes and ketones (→ 8), α,β-unsaturated ketones (→ Michael adducts 13 and 14), and ω-nitrostyrenes (→ 15) in the benzylic position. With acyl chloride and chloro-trimethylsilane attack occurs probably on an oxygen of 6 (see intermediates 17-19). A representation of the novel reagents, best compatible with the chemical results, is that of super-enamines 16b; their charge affinity is compared with that of nitroethanes (the precursors) and that of nitroethylenes (the oxidized forms, see 2 → 3), and it is shown in table 1 that they are nitroolefins with reactivity umpolung or homonitronates. The comparison made in table 2 demonstrates that the dilithio derivatives 6 are synthetically equivalent with enamines and enolates of normal reactivity (“double umpolung”).
    Notes: β-Arylnitroethane 4 können bei -80 bis -90°C in HMPTA-haltigem THF mit zwei Equivalenten n-Butyllithium zu den Dilithiumderivaten 6 doppelt deprotoniert werden, die man als Reduktionsprodukte (s. 3 und 16b) von ω-Nitrostyrolen 2 auffassen kann. Sie reagieren mit Alkylhalogeniden (→ 7), Aldehyden und Ketonen (→ 8), α,β-ungesättigten Ketonen (→ Michael-Addukte 13 und 14) und ω-Nitrostyrolen (→ 15) am benzylischen C-Atom. Säurechlorid und Trimethylchlorsilan greifen wahrscheinlich am Sauerstoff an (s. Zwischenprodukte 17-19). Als mit den chemischen Befunden am besten vereinbare Schreibweise für die neuartigen Reagentien schlagen wir die von Super-enaminen 16b vor; in Tab. 1 ist ihre Ladungsaffinität mit der von Nitroethanen (den Vorläufern) und von Nitroethylenen (den oxidierten Formen, s. 2 → 3) verglichen und gezeigt, daß sie umgepolte Nitroolefine oder Homonitronate sind. Die Gegenüberstellung in Tab. 2 demonstriert. Daß die Dilithiumverbindungen 6 als Synthesebausteine für Amine und Carbonylverbindungen normale Reaktivität haben („Doppelumpolung“).
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120121
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    Unerwartete Ringschlußreaktionen 2,2-disubstituierter N-Alkoxy-3-hydroxypropionamide mit Arylisocyanaten (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 600-606 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Unexpected Cyclisations of 2,2-Disubstituted N-Alkoxy-3-hydroxypropionamides with Aryl IsocyanatesTreatment of 2,2-disubstituted N-alkoxy-3-hydroxypropionamides (8) with aryl isocyanates (9) in a mole ratio of 1:2 in boiling benzene and in the presence of triethylamine yields 3-alkoxytetrahydro-2H-1,3-oxazine-2,4-diones (10) and 3-aryltetrahydro-2H-1,3-oxazine-2,4-diones (11). Formation of 10 and 11 depends largely on the nature of the substituents at C-2 of 8. In consequence of the cyclisation reactions ureas of type 13 and 14 and the 3-alkoxybiuret 15 are produced.
    Notes: 2,2-Disubstituierte N-Alkoxy-3-hydroxypropionamide (8) reagieren mit Arylisocyanat (9) im Molverhältnis 1:2 bei 80°C in Gegenwart von Triethylamin zu 3-Alkoxytetrahydro-2H-1,3-oxazin-2,4-dionen (10) und 3-Aryltetrahydro-2H-1,3-oxazin-2,4-dionen (11). Die Cyclisierungsrichtung zu 10 oder 11 wird maßgeblich von der Natur der Substituenten an C-2 von 8 bestimmt. Als Folge der Cyclisierungen lassen sich die Harnstoffe 13 und 14 sowie das 3-Alkoxybiuret 15 isolieren.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120222
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    Nucleosidtransformationen, V. Umwandlung von Guanosin in 2′-Desoxy-, 3′-Desoxy-, 2′,3′-Anhydro- sowie xylo-Guanosin (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 625-639 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleoside Transformations, V. Transformation of Guanosine into 2′-Deoxy, 3′-Deoxy-, 2′,3′-Anhydro- and xylo-Guanosine3′-und 2′-deoxyguanosine (12 and 13, respectively) are obtained from guanosine (1) upon reaction with trimethyl orthoacetate, pivaloyl chloride/pyridine, tributyltin hydride and sodium methylate through the intermediates 2, 3a/4a. 2-N,5′-O-Dipivaloyl-2′,3′-anhydroguanosine (14) is formed on treatment of the 3′-iodoguanosine derivative 10 with potassium phthalimide. The 2′.3′-anhydroderivatives 14-16 form N-3 → C-3′-cyclonucleosides in aqueous solution. Stirring of 14 with a boron trifluoride etherate solution yields xylo-guanosine derivative 22.
    Notes: 3′-und 2′-Desoxyguanosin (12 bzw. 13) werden, ausgehend von Guanosin (1), durch Umsetzung mit Orthoessigsäure-trimethylester, Pivaloylchlorid/Pyridin, Tributylzinnhydrid und Natriummethylat über die Zwischenstufen 2, 3a/4a dargestellt. 2-N,5′-O-Dipivaloyl-2′,3′-anhydroguanosin (14) entsteht bei Behandlung des 3′-Iodguanosin-Derivats 10 mit Phthalimidkalium. In wäßriger Lösung zeigen die 2′,3′-Anhydroguanosin-Derivate 14-16 N-3 → C-3′-Cyclonucleosid-Bildung. Das xylo-Guanosin-Derivat 22 entsteht aus 14 beim Rühren mit einer Bortrifluoridetherat-Lösung.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120224
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    Zum Mechanismus der Hydrierung bei Friedel-Crafts-Reaktionen α,β-ungesättigter Säuren mit Benzol (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 689-699 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Mechanism of Hydrogenation During Friedel-Crafts Reactions of α,β-Unsaturated Acids with BenzeneThe intermediate in the reaction of 3,3-diphenylpropenoic acid (1) with benzene/AlCl3 is the resonancestabilized carbenium ion 8. It reacts to give a mixture containing the products of hydrogenation 2 and of addition of benzene 3. Several artefacts of the working up (4 - 7) are found.  -  In the reactions of deuterated compounds hydrogen scrambling both in the phenyl groups and  -  to a smaller extent  -  in the α-position occurs.  -  Hydrogen (hydrid ions) derived from benzene, not from the side chain of a second molecule 1, is transferred to the β-position of 1.
    Notes: Die Umsetzung von 3,3-Diphenylpropensäure (1) mit Benzol/A1Cl3 führt über das mesomeriestabilisierte Carbenium-Ion 8 zu einem Substanzgemisch, in dem neben dem Hydrierungs- und dem Benzoladditionsprodukt (2 bzw. 3) Artefakte der Aufarbeitung,(4 - 7) enthalten sind.  -  Bei Einsatz deuterierter Ausgangsverbindungen tritt Äquilibrieren der Aryl- und (in geringem Umfang) der α-ständigen Wasserstoffe ein.  -  Bei der Hydrierung von 1 wird Wasserstoff des Benzols  -  nicht aber Wasserstoff aus der Seitenkette eines zweiten Moleküls 1  -  als Hydrid-Ion in die β-Stellung von 1 eingebaut.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120230
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  • 75
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    Zur Autoxidation von cyclischen Iminen, I (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 734-742 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Autoxidation of Cyclic Imines, IIn a noncatalyzed reaction cyclic imines, e. g. 1a-d, bearing one or two α-tert. carbon atoms are oxidized by molecular oxygen. Usually, the products are relatively unstable α-iminohydroperoxides, which are subject to further rearrangement or reduction. These compounds are partially further oxidized. The isolation of the products as well as their structure elucidation by spectroscopic methods are established.
    Notes: Cyclische Imine mit einem oder zwei tert. α-C-Atomen, z.B. 1a-d, werden durch nichtsensibilisierten Sauerstoff oxidiert. Primär entstehen dabei meist instabile α-Iminohydroperoxide, die Folgereaktionen wie Umlagerung und Reduktion eingehen. Diese Verbindungen werden teilweise erneut oxidiert. Die Produkte der Autoxidation werden isoliert und ihre Konstitutionen ermittelt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120235
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    Schonende Veresterung von N-terminal geschützten Aminosäuren mittels der Vier-Komponenten-Kondensation (4 CC) (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 776-777 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mild Esterification of N-protected Amino Acids via Four-Component Condensation (4 CC)We describe the esterification of N-protected amino acid derivatives, e. g. glycine derivatives and Boc-Leu-OH, with methanol or ethanol, respectively, by the action of an enamine and an isocyanide.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19791120239
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    Notizen. Dimerisierung von Diphenyl(trifluoracetyl)phosphanoxid (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 773-775 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dimerization of Diphenyl(trifluoroacetyl)phosphane OxideAt -25°C the phosphane oxide CF3C[(O)P(O)Ph2]2OC(O)CF3 (1) dimerizes to the trifluoroacetate CF3C[(O) PPh2]2OC(O)CF3 (2a), which is sensitive to hydrolysis and, at 40°C is transformed irreversibly into the phosphinate CF3C[(O)PPh2][OP(O)Ph2]C(O)CF3(3a). In contrast to 2a, the thermally more stable homologous octanate C7F15C[(O)PPh2]2OC(O)C7F15 (2b) is obtained from Ph2PCI and C7F15CO2H.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120238
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    Masthead (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120301
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    In memoriam Walter Hieber 1895-1976 (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. XXI 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120241
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    Heterocyclische Siebenring-Verbindungen, XXII. Synthese und thermische Umlagerung von substituierten 4-Phenyl-1-benzothiepin-1-oxiden (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 781-792 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Heterocyclic Seven-membered Ring Compounds, XXII. Synthesis and Thermolysis of Substituted 4-Phenyl-l -benzothiepin 1-Oxides4-Phenyl-l-benzothiepin l-oxides 3a and b have been prepared as well via the benzothiepinone 1-oxide 2 as by direct oxidation of the parent 1-benzothiepins 6a and b. The synthesis of 3c and d was only accomplished by the second way. Further oxidation of 3a-d yielded the thermally stable dioxides 4a-d. Thermolysis of 3a-d produced the corresponding naphthalenes 5a-d by elimination of SO. The rates of the reaction 3→5 have been estimated for one temperature each.
    Notes: Die 4-Phenyl-l-benzothiepin-l-oxide 3a und b wurden sowohl über das Benzothiepinon-1-oxid 2 als auch durch direkte Oxidation der entsprechenden 4-Phenyl- 1-benzothiepine 6a und b dargestellt. Die Synthese von 3c und d erfolgte nur auf dem zweiten Weg. Weiteroxidation von 3a-d führte zu den thermisch stabilen Dioxiden 4a-d. Die Thermolyse von 3a-d lieferte unter Abspaltung von SO die entsprechenden Naphthaline 5a-d. Die Geschwindigkeitskonstanten der Reaktion 3→5 wurden für je eine Temperatur bestimmt.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19791120302
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    Bevorzugte O-Glycosidbildung bei der Ribosidierung von 5-Methyl-2-methylthio-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-on (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 799-806 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Favoured Formation of an O-Glycoside during Ribosidation of 5-Methyl-2-methylthio-7H-pyrrolo-[2,3-d]pyrimidin-4(3H)-one6-Amino-5-(2,2-diethoxy-l-methylethyl)-2-mercaptopyrimidin-4-ol (3a) has been prepared via condensation of racem. ethyl 2-cyano-4,4-diethoxy-3-methylbutyrate (2) and thiourea. Alkylation of 3 a at 2-SH with dimethyl sulfate is accompanied by ring closure yielding 5-methyl-2-methylthio-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one (4b). Silylation of 4b followed by reaction with 2,3,5-tri-O-acetyl-1-bromo-D-ribofuranose in the presence of mercury(II) salts (Wittenburg conditions) gives the O-glycoside 6a and not the N-7-glycoside formerly obtained during ribosidation of 2-methylthio-7H-pyrrolo[2,3-b]pyrimidin-4(3H)-one12). Hydrolysis of 6a under mild conditions leads to deacetylation giving 5-methyl-2-methylthio-4-(D-ribofuranosyloxy)-7H-pyrrolo[2,3-d]pyrimidine (6b). The latter compound shows UV spectra similar to 4-methoxy-5-methyl-2-methylthio-7H-pyrrolo[2,3-d]pyrimidine (4c) down to pH 2, but at lower pH values hydrolysis of the glycosidic bond occurs.
    Notes: 6-Amino-5-(2,2-diethoxy-1-methylethyl)-2-mercaptopyrimidin-4-of (3 a) wurde durch Kondensation von racem. 2-Cyan-4,4-diethoxy-3-methylbuttersäure-ethylester (2) und Thioharnstoff gewonnen. Die Alkylierung von 3a mit Dimethylsulfat führt zur Methylierung an 2-SH, wobei gleichzeitig Cyclisierung zu 5-Methyl-2-methylthio-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-on (4b) erfolgt. Verknüpft man silyliertes 4 b mit 2,3,5-Tri-O-acetyl-l-brom-D-ribofuranose in Gegenwart von Quecksilber(II)-Salzen (Wittenburg-Bedingungen), so entsteht das O-Glycosid 6a und nicht wie bei der Reaktion von 2-Methylthio-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-on das N-7-Glycosid12). Durch milde Hydrolyse von 6a erhält man 5-Methyl-2-methylthio-4-(D-ribofuranosyloxy)-7H-pyrrolo[2,3-d]pyrimidin (6b), dessen UV-Spektren bis pH 2 denen von 4-Methoxy-5-methyl-2-methylthio-7H-pyrrolo[2,3-d]pyrimidin (4c) gleichen, im stärker Sauren jedoch Glycosid-Hydrolyse anzeigen.
    Additional Material: 1 Ill.
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    Totalsynthese von Papaverrubin E (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 849-852 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Total Synthesis of Papaverrubine EThe phthalide isoquinoline alkaloid (-)-bicuculline (la), which has previously been prepared by total synthesis, is transformed into racemic papaverrubine E (±)-(6a), its natural (+)- and its unnatural (-)-enantiomer.
    Notes: Das totalsynthetisch zugängliche Phthalidisochinolinalkaloid (-)-Bicucullin (la) wird in das Racemat des Benzazepinalkaloids Papaverrubin E (±)-(6a) sowie in sein natürliches (+)-bzw. unnatürliches (-)-Enantiomeres übergeführt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120310
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    Basische Metalle, XI. Kationische (Cyclopentadienyl)rhodium-Komplexe mit Rh—H-, Rh—C-, Rh—Ge-, Rh—Sn- und Rh—Halogen-Bindungen (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 834-843 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Basic Metals, XI. Cationic (Cyclopentadienyl)rhodium Complexes Containing Rh—H-, Rh—C-, Rh—Ge-, Rh—Sn-, and Rh—Halogen Bonds[C8H12RhCl]2 reacts with excess trimethylphosphane to give [(PMe3)4Rh]Cl (1). A very rapid exchange of the phosphane ligands occurs in solution of 1. The reaction of 1 with T1C5H5 leads to the complex C5H5Rh(PMe3)2 (9), in which the metal atom is a strong Lewis base. 9 reacts very readily with electrophiles Y+ to give the cations [C5H5(PMe3)2RhY]+ which possess stable Rh—H, Rh-alkyl, Rh—acyl, Rh—Ge, Rh—Sn, and Rh—halogen bonds. They were isolated as PF6 salts [Y = H (2), CH3 (3), C2H5 (4), COCH3 (10), COC6H5 (11), COC6H4OMe-(p) (12), GeMe3 (7). SnMe3 (8). Br (15), cl (13), I (14). The cation Me3SiC5H4(PMe3)2RhH ]+ is formed together with [C5H5(PMe3)2RhH]+ in the reaction of 9 with CF3SO3SiMe3, in ether. Reduction with NaH in THF gives Me3SiC5H4Rh(PMe3)2.
    Notes: [C8H12RhCl]2 reagiert mit einem Überschuß von Trimethylphosphan zu [(PMe3)4Rh]Cl (1). In Lösungen von 1 findet ein sehr rascher Austausch der Phosphanliganden statt. Die Reaktion von 1 mit TIC5H5 führt zu dem Komplex C5H5Rh(PMe3)2 (9), der ein stark Lewis-basisches Metallatom besitzt. 9 reagiert mit Elektrophilen Y+ sehr bereitwillig zu den Kationen [C5H5(PMe3)2RhY]+ die stabile Rh—H-, Rh—Alkyl-, Rh—Acyl-, Rh—Ge-, Rh—Sn- und Rh—Halogen-Bindungen besitzen und als PF6-Salze isoliert werden [Y = H (2), CH3 (3), C2H5 (4), COCH3 (10), COC6H5 (11), COC6H4OMe-(p) (12), GeMe3 (7), SnMe3 (8), Br (15), Cl (13). 1(14)]. Bei der Reaktion von 9 mit CF3SO3SiMe3 in Ether entsteht neben [C5H5(PMe3),2RhH] + das Kation [Me3SiC5H4(PMe3)2RhH]+. Die Reduktion mit NaH in Tetrahydrofuran ergibt Me3SiC5H4Rh(PMe3)2.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19791120308
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    Photoelektronenspektren und Konformationen bi- und tricyclischer Hexahydro-1,2,4,5-tetrazine (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 853-861 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photoelectron Spectra and Conformations of Bi- and Tricyclic Hexahydro-1,2,4,5-tetrazinesThe photoelectron spectra of three tricyclic (2-4) and three bicyclic (5-7) hexahydro-1,2,4,5-tetrazines have been interpreted with regard to gas phase conformations. The interactions of the n-orbitals have been studied by MINDO/2 calculations for different conformations of hexahydro-1.2.4,5-tetrazine (1). The observed n-electron ionization potentials permit the identification of tetraequatorial forms of 2-4 and diequatorial-diaxial forms of 5-7 as the dominant conformers. In addition, for 2 and 5 other less stable conformers could be detected.
    Notes: Die Photoelektronenspektren von drei tricyclischen (2-4) und von drei bicyclischen (5-7) Hexahydro-1,2,4,5-tetrazinen wurden hinsichtlich der in der Gasphase vorliegenden Konformeren ausgewertet. Für die infrage kommenden Konformationen wurden zum Studium der Wechselwirkung der n-Orbitale MINDO/2-Rechnungen an der Stammverbindung (1) ausgeführt. Anhand der beobachteten n-Ionisationsbanden lassen sich bei 2-4 tetraäquatoriale und bei 5-7 diäquatorial-diaxiale Formen als stabilste Konformere identifizieren. Bei 2 und 5 wurden daneben weniger stabile Konformere nachgewiesen.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19791120311
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    Struktur und innere Beweglichkeit sterisch fixierter s-cis-Butadiene (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 890-898 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Structure and Internal Flexibility of Sterically Fixed s-cis-ButadienesForce Field Calculations yield a coplanar arrangement of the π systems of the vicinal exo-methylene derivatives 1 and 2 of cyclobutane and cyclopentane and of the corresponding derivatives 4-7 of norbornane, bicyclooctane, bicyclononane and bicyclooctene. The detailed geometry of the cis-butadiene unit is essentially determined by the ring system. For the cyclohexane derivative 3 on the other hand a chair conformation is obtained. 2,5 and 6 are rather flexible molecules for which torsions of the π system up to 20° require energies less than 5 kJ/mol, whereas for the more rigid systems 1, 4 and 7 approximately 10 kJ/mol are necessary for twisting the π system by 10°.
    Notes: Kraftfeldrechnungen ergeben für die vicinalen exo-Methylenderivate 1 und 2 des Cyclobutans und des Cyclopentans sowie für die entsprechenden Derivate 4-7 des Norbornans, Bicyclooctans, Bicyclononans und des Bicyclooctens eine planare Anordnung des π-Systems. Dessen genaue Geometrie im wesentlichen durch das cyclische Gerüst bestimmt wird. Das Cyclohexanderivat 3 dagegen liegt in einer Sesselform vor. Die Moleküle 2, 5 und 6 zeichnen sich durch große Flexibilität aus, Torsionen des π-Systems bis etwa 20° erfordern Energien von weniger als 5 kJ/mol, während für die starreren Systeme 1,4 und 7 bereits bei Verdrillungen um 10° etwa 10 kJ/mol erforderlich sind.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19791120314
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    Ligandstruktur und Komplexierung, XLIV. Synthese und Selektivität neuartiger vierarmiger nichtcyclischer Neutralliganden (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 899-907 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ligand Structure and Complexation, XLIV. Synthesis and Selectivity of New Four-Armed Noncyclic Neutral LigandsNew, noncyclic neutral ligand systems 4-6 and 8-11 of the tetrapode type 3, equipped with various end groups, were synthesized. The cation selectivity depends on the structure of the end groups. The potentiometrically determined values of the complex stability constants as a rule lie between those of the analogous tripode (2) and dipode ligands (1). Numerous complexes between the four-armed complexing agents and several dipodands (14-16) and alkali and alkaline earth metal salts are reported.
    Notes: Neue nichtcyclische Neutralligandsysteme 4-6 und 8-11 vom Tetrapodentyp 3 mit verschiedenen Endgruppen wurden synthetisiert. Die Kation-Selektivität hängt von der Endgruppenstruktur ab. Die potentiometrisch bestimmten Komplexstabilitätskonstanten liegen i. a. zwischen denjenigen der Tripoden- (2) und Dipoden-Liganden (1). Zahlreiche kristalline Komplexe der vierarmigen Komplexbildner sowie einiger zum Vergleich synthetisierter neuer Dipodanden (14-16) mit Alkali- und Erdalkalimetallsalzen wurden erhalten.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19791120315
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    Über N-Silyl- und N-Germylpyridinyl-Radikale sowie ihre Stabilisierungsreaktionen (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 936-949 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: N-Silyl and N-Germylpyridinyl Radicals, and Their Stabilization ReactionsPyridines, functionally substituted in 2-, 3-, or 4-position, give N-silylpyridinyls (3, 7, 11, 16, 19, 23) upon reaction with (Me3Si)2Hg, and further on mostly N,ω-bis(silyl) derivatives (5), tetrahydro-4,4′-or -2,2′-bipyridines (9, 17, 20, 21, 24, 25), depending on mesomeric and steric conditions. 2- and 3-acylpyridines yield O-silylated hydropyridoins (27, 30), 2-cyanopyridine forms a persistent pyridinyl (29). N-Germylpyridinyls (32-34) are generated for the first time. With (Me3Ge)2Hg, they are formed, however, only in the case of substituted pyridines of low electron density or strong mesomeric stabilization of the radicals. Several N ω-bis(germyl)-dihydropyridines (36, 37) rearrange, in part even at -30°C, with a surprising N, C-migration of a germyl residue, restoring the aromatic system, giving 35, 39. ESR data are given for most of the generated radicals.
    Notes: In 2-, 3- oder 4-Stellung funktionell substituierte Pyridine geben mit (Me3Si)2Hg N-Silylpyridinyle (3, 7, 11, 16, 19, 23), die je nach Mesomeriestabilisierung und sterischer Hinderung meistens zu N,ω-Bis(silyl)-Derivaten (5) oder zu Tetrahydro-4,4′- bzw. -2,2′-bipyridinen (9, 17, 20, 21, 24, 25) weiterreagieren. 2- und 3-Acylpyridine ergeben O-silylierte Hydropyridoine (27, 30), 2-Cyanpyridin ein kinetisch stabiles Pyridinyl (29). N-Germylpyridinyle (32-34) werden erstmals erhalten. Sie entstehen mit (Me3Ge)2Hg nur im Falle elektronenarmer substituierter Pyridine bzw. starker Mesomeriestabilisierung der Radikale. Bei N,ω-Bis(germyl)dihydropyridinen (36, 37) wurde, z. T. schon bei -30°C, eine überraschende N,C-Wanderung eines Germylrestes unter Rückbildung des aromatischen Systems zu 35, 39 gefunden. Für die meisten der erhaltenen Radikale werden die ESR-Daten angegeben.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19791120317
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    Stoffwechselprodukte von Mikroorganismen, 172. Isolierung des Antibioticums semi-Vioxanthin aus Penicillium citreo-viride und Synthese des Xanthomegnins (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 957-978 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metabolic Products of Microorganism, 172. Isolation of the Antibiotic semi-Vioxanthin from Penicillium citreo-viride and Synthesis of XanthomegninBesides xanthomegnin (16 b), 3,4-dehydroxanthomegnin (29a), viomellein (23) and vioxanthin (3) from Penicillium citreo-viride under different culture conditions semi-vioxanthin (7) was isolated. Structure 7 has been established by its spectra and the fact that oxidation with Fremy's salt gives 3,4,6,9-tetrahydro-10-hydroxy-7-methoxy-3-methyl-1,6,9-trioxo-1H-naphtho[2,3-c]pyran (9a = semi-xanthomegnin). -9c, prepared by demethylation of 9a, was dimerized by potassium peroxydisulfate/sodium hydroxide and methylated, giving 16b. Synthetic 16b and authentic xanthomegnin were identical, which verifies the structure revised by Höfle and Röser9) and shows, that the dyes of the xanthomegnin series are biogenetically homogenous. - The metabolic products of the strain inhibit the growth of bacteria. 16b and 26 furthermore have an effect against insects.
    Notes: Neben Xanthomegnin (16b), 3,4-Dehydroxanthomegnin (29 a), Viomellein (23) und Vioxanthin (3) wurde aus Penicillium citreo-viride unter veränderten Kulturbedingungen semi-Vioxanthin (7) isoliert. Konstitution 7 folgt aus den Spektren und dem Befund, daß mit Fremy-Salz 3,4,6,9-Tetrahydro-10-hydroxy-7-methoxy-3-methyl-1,6,9-trioxo-1H-naphtho[2.3-c]pyran (9a = semi-Xanthomegnin) entsteht. - Das durch Entmethylierung von 9a zugängliche 9c ließ sich mit Kaliumpersulfat/Natriumhydroxid zu 16a dimerisieren, das zu 16b methyliert wurde. Synthetisches 16b war mit nativem Xanthomegnin identisch, was die von Höfle und Röser9) revidierte Konstitution bestätigt und beweist, daß die Farbstoffe der Xanthomegnin-Reihe biogenetisch einheitlich sind. - Die Stoffwechselprodukte des Stammes hemmen das Wachstum von Bakterien, 16b und 23 wirken ferner gegen Insekten.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19791120319
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    Mikrobiologische Umwandlung von Steroiden, XVI. Synthese von 11β, 21-Dihydroxy-6, 16α-dimethyl-1,4,6,-pregnatrien-3,20-dion und dessen 11-Ketoverbindung (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 979-989 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Microbial Transformations of Steroids XVI. Synthesis of 11β,21-Dihydroxy-6, 16α-dimethyl-1,4,6-pregnatriene-3,20-dione and of its 11-Keto Compound21-Acetoxy-5α,6α-epoxy-3β-hydroxy-6β16α-dimethyl-20-pregnanone (3a), prepared from 3β-hydroxy-6, 16α-dimethyl-5-pregnen-20-one (1) by epoxidation and chemical introduction of the 21-acetoxy group, was oxidized to 6α,21-dihydroxy-6β,16α-dimethyl-4-pregnene-3,20-dione (4) by Flavobacterium dehydrogenans and dehydrated to the 3-keto-4,6-diene 5. The 11β-hydroxy group was introduced by Curvularia lunata to give 6, and the 11α-hydroxy group by Aspergillus ochraceus to yield 8. Both compounds were dehydrogenated with Bacillus lentus to from 7 and 9. The 11α-hydroxy compound 9 was selectively acetylated to 10, which was oxidize to 11. This on saponification yielded 12.
    Notes: 21-Acetoxy-5α,6α-epoxy-3β-hydroxy-6β,16α-dimethyl-20-pregnanon (3a), dargestellt aus 3β-Hydroxy-6, 16α-dimethyl-5-pregnen-20-on (1) durch Epoxidierung und 21-Acetoxylierung, wurde mit Flavobacterium dehydrogenans zu 6α,21-Dihydroxy-6β, 16α, -dimethyl-4-pregnen-3,20-dion (4) oxidiert und zu 21-Hydroxy-6, 16α-dimethyl-4,6-pregnadien-3,20-dion (5) dehydratisiert. Mit Curvularia lunata wurde die 11β-Hydroxygruppe eingeführt zu 6, während Aspergillus ochraceus die entsprechende 11α-Hydroxyverbindung 8 ergab. Beide Verbindungen wurden mit Bacillus lentus zu 7 bzw. 9 dehydriert. Die 11α-Hydroxyverbindung 9 wurde nach selektiver Acetylierung der 21-Hydroxygruppe zu 10 zum 11-Keton 11 oxidiert, dessen Verseifung 12 ergab.
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    URL: http://dx.doi.org/10.1002/cber.19791120320
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    Neue Synthesen mit Diazodiketonen, IV. Cyclische S-Oxide (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1012-1022 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: New Syntheses with diazodiketones, VI. Cyclic S-OxidesThe S-oxides 4 of 3,4-dihydro-1,2,3-oxathiazines and 5 of 1,2-oxazetidines are prepared a) by thermolyzing diazodiketones 1 with N-Sulfinylamines 3; b) by condensing the 2-acylacetamides 6 which are readily accessible from 1, with thionyl chloride in the presence of a basic catalyst. From 6, the aminoacrylamides 7 are obtained. These react with thionyl chloride according to the base employed, to afford either the monocyclic 3,6-dihydro-1,2,6-thiadiazine-S-osides 10 or the 4-amino-quinolines 8, presumably via the intermediacy of an imine 9. - The introduction of the SO group into (hetero)cyclic iminocarboxamides, diamines or aminophenols give rise to the S-oxides 13 of condensed thiadieazines, 15a-c of benzothiadiazole, or 15d of benzoxathiazole, respectively.
    Notes: Die 3,4-Dihydro-1,2,3-oxathiazin- 4 und 1,2-Oxazetidin-S-oxide 5 werden a) durch Thermolyse der Diazodiketone 1 mit N-Sulfinylaminen 3 b) durch basenkatalysierte Kondensation der aus 1 leicht zugänglichen 2-Acylacetamide 6 mit Thionylchlorid hergestellt. Aus 6 weden die Aminoacrylamide 7 erhalten. Diese reagieren mit Thionylchlorid je nach der verwendeten Base entweder zu monocyclischen 3,6-Dihydro-1,2,6-thiadiazin-S-oxiden 10 oder über eine Imidoylketenimin Zwischenstufe 9 zu den 4-Aminochinolinen 8. - Der SO-Einbau mittels Thionylchlorid in (hetero)-cyclische Iminocarboxamide, Diamine und Aminophenole führt zu den S-oxiden 13 kondensierter Thiadiazine, 15a-c des Benzothiadiazols bzw. 15d des Benzoxathiazols.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19791120323
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    Untersuchungen zur Modifizierung der Mannobiose und Synthese von Methyl-4-O-β-D-rhamnosyl-α-D-olivosid (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1035-1045 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on the Modification of Mannobiose and Synthesis of Methyl 4-O-β-D-Rhamnosyl-α-D-OlivosideBy acid-catalyzed reaction of α-mannobiose octaacetate (2) with trichloroethanol or phenol the glycosides 6 or 9a, and with hydrogen bromide/acetic acid the glycosyl bromide 3 are obtained. Koenigs-Knorr reaction of 3 with methanol of benzyl alcohol yields the orthester derivatives 7a or 7b, respectively. Mannobial hexaacetate 8 is obtained from 3 an d transformed into 12a by iodomethoxylation. The selective tosylations of 9b or 12b in the 6- and 6′ -positions yields the ditosylates 10 or 13a, which in turn give the corresponding diiodo compounds 11a or 5a, respectively. By subsequent reduction using nickel chloride/sodium borohydride the syntheses of the glycosides 14 and 17b of 4-O-(β-D-rhamnopyranosyl)-α-D-rhamnopyranose or 4-O-(β-D-rhamnopyranosyl)-α-D-olivopyranose, respectively, are achieved. All new compounds are characterized by peracetates, and their structural assignment is confirmed from their NMR spectra.
    Notes: α-Mannobiose-octaacetat (2) läßt sich sauer katalysiert mit Trichlorethanol oder Phenol zu den Glycosiden 6 bzw. 9a oder mit Bromwasserstoff in Eisessig zum Glycosylbromid 3 umsetzen. Koenigs- Knorr-Reaktion von 3 mit Methanol oder Benzylalkohol ergibt die Orthoester 7a bzw. 7b. Aus 3 wird Mannobial-hexaacetat 8 gewonnen und zu 12a iodmethoxyliert. 9b bzw. 12b lassen sich selektiv in 6- und 6′- Position zu 10 bzw. 13a tosylieren und anschließend in die entsprechenden Iodide 11a bzw. 15a überführen. Deren Reduktion mit Nickelchlorid/Natriumboranat in Ethanol erlaubt die Darstellung der Glycoside 14 and 17b von 4-O-(β-D- Rhamnopyranosyl)-α-D-rhamno-pyranose bzw. 4-O-0(β-D-Rhamnopysanosyl)-α-D-olivopyranose. Alle Syntheseprodukte werden durch Peracetate charakterisiert und strukturell an Hand der NMR-Spektren zugeordnet.
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    URL: http://dx.doi.org/10.1002/cber.19791120325
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    Synthese, Strukturaufklärung und Konformationsuntersuchungen 1→4-verknüpfter Disaccharidglycoside vom 2,3-Anhydro-4-O-(hex-2-enopyranosyl)-α-D-allopyranosid-Typ (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1023-1034 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis, Structure Elucidation, and Conformational Studies of 1→4-Linked Disaccharide Glycosides of the 2,3-Anhydro-4-O-(hex-2-enopyranosyl)-α-D-allopyranoside TypeTriacetyl-D-glucal (1) or tetraacetyl-2-hydroxy-D-glucal (6) and 2,3-anhydro-α-D-allopyranosides 2 or 7, respectively, undergo smooth acid-catalyzed allylic rearrangement reactions to yield the crystalline α-linked disaccharide derivatives 4, 5, and 9 with hex-2-enopyranosyl structure in the non-reducing rings in good yields. By hydrogenation of 4 and 5, 8 is obtained, in which the α-linkage can be demonstrated. X-ray analysis confirms the interglycoside α-linkage in the considerably stretched disaccharide derivative 5. Both the saccharide ring adopt SO5 sofa conformations, in which only C-5 and C-5′ ae observed significantly below the plane of the remaining ring atoms. The NMR data of 5 and 9 suggest also SO5 sofa conformation in solution. On the contrary the β-isomer 10 adopts 5SO sofa conformation which is consistent with the allylic effect.
    Notes: Durch sauer katalysierte Addition der 2,3-Anhydro-α-D-allopyranoside 2 bzw. 7 an Triacetyl-D-glucal (1) bzw. Tetraacetyl-2-hydroxy-D-glucal (6) lassen sich unter Allylumlagerung die α1→4-verknüpften Disaccharide 4, 5 und 9 mit Hex-2-enopyranosyl-Struktur im nicht-reduzierenden Saccharidring milde und in guten Ausbeuten kristallin gewinnen. Durch Hydrierung von 4 und 5 wird 8 erhalten, bei dem die interglycosidische α-Verknüpfung nachgewiesen wird. Die Röntgenstrukturanalyse von 5 bestätigt die α-Verknüpfung in dem erheblich gestreckten Disaccharidderivat. Beide Saccharidringe weisen eine SO5-Sofakonformation auf, bei der nur die Atome C-5 und C-5′ wesentlich aus der Ebene der übrigen Ringatome nach unten herausstehen. Konformationsbetrachtungen legen auch in Lösung für 5 und 9 das Vorliegen einer SO5-Sofakonformation nahe. Das interglycosidische β-Isomere 10 weist dagegen eine 5SO-Sofakonformation auf, was auf den Allyleffekt zurückgeführt werden kann.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120324
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  • 93
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    Untersuchungen zur Modifizierung der Laminaribiose und Synthese von Methyl-3-O-β-D-chinovosyl-α-D-olivosid (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1046-1056 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on the Modification of Laminaribiose and Synthesis of Methyl 3-O-β-D-Quinovosyl-α-D-olivosideLaminaribiose (2) and the peracetates 3a and b are obtained by acetolysis of laminaran or pachyman, respectively. Via formation of the bromide 5, the β-methyl (6) and β-benzyl glycosides (7a and b) as well as the glycals 9a and b are obtained in crystalline form. Iodoalkoxylations with benzyl alcohol yield the epimeric benzyl glycosides 10a and b, whereas with methanol 11a is obtained exclusively. 11b is transformed into the dibenzylidene compounds 12a-c. the reaction of which with N-bromosuccinimide leads to the formation of the 2,6,6′- trihalo derivatives 13a and b. By subsequent reduction the title compound 14b is obtained and characterized as its peracetate.
    Notes: Ausgehend von Laminaribiose (2) und ihren Peracetaten 3a und b, die durch Acetolyse von Laminaran bzw. Pachyman zugänglich sind, lassen sich über das Bromid 5 die β-Methyl- (6) und β-Benzylglycoside (7a und b) sowie die Glycale 9a und b kristallin gewinnen. Iodalkoxylierung mit Benzylalkohol gibt die epimeren Benzylglycoside 10a und b, während mit Methanol einheitlich 11a isoliert wird. Aus 11b werden die Dibenzylidenverbindungen 12a-c dargestellt, deren Öffnung mit N-Bromsuccinimid zu den 2,6,6′-Trihalogenderivaten 13a und b führt. Durch Reduktion wird daraus die Titelverbindung 14b gewonnen und als Peracetat charakterisiert.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120326
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  • 94
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    Tertiäres Phosphan/Hexachlorethan als Kondensationsreagenz für die Peptidsynthese (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1057-1063 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Tertiary Phosphane/Hexachloroethane as Condensing Agent in Peptide SynthesisThe action of tertiary phosphane/hexachloroethane on N-protected amino acids and amino acid esters is found applicable for peptide synthesis. No difficulties are found when the side chains of serine, threonine, tyrosine, asparagine and glutamine are present. By addition of 1-hydroxybenzotriazole racemisation is prohibited as indicated by the test of Anderson.
    Notes: Mit dem Dehydratisierungsreagenz tertiäres Phosphan/Hexachlorethan lassen sich N-geschützte Aminosäuren und Aminosäureester in hohen Ausbeuten zu Peptiden kondensieren. Funktionelle Gruppen in den Seitenketten von Serin, Threonin, Tyrosin, Asparagin und Glutamin werden nicht angegriffen Unter Zusatz von 1-Hydroxybenzotriazol verläuft der Anderson-Test racemisierungsfrei.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120327
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  • 95
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    Synthetische Arbeiten in der Reihe der aromatischen Erythrina-Alkaloide, XXIII. 1,7-Cyclo-cis-erythrinane (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1110-1125 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of Aromatic Erythrina Alkaloids, XXIII. 1,7-Cyclo-cis-erythrinanesThe 1,7-cyclo-cis-erythrinane derivative 17 is formed by heating the bromo compound 13 with potassium hydroxide in diethylene glycol to 180°C. Hydrolysis of 17 yields the ketone 18 which, by reactions of the carbonyl group, is transformed into the cyclic compounds 19 - 21 and 27 - 33. The cyclopropane ring is easily cleaved by reduction to give the unsaturated lactam 10 or the saturated lactam 1. The 1,7-cyclo-cis-erythrinane structures 37 and 38 can be synthesized by way of the cyclic olefin 35.
    Notes: Durch Erhitzen der Bromverbindung 13 mit Kaliumhydroxid in Diethylenglycol auf 180°C entsteht das 1,7-Cyclo-cis-erythrinan-Derivat 17. Nach Hydrolyse zum Keton 18 erhält man durch Umwandlung der Ketogruppe die Cycloverbindungen 19 - 21 und 27 - 33. Reduzierende Bedingungen spalten den Cyclopropanring sehr leicht auf unter Bildung des Olefinlactams 10 oder des gesättigten Lactams 1. Über das Cycloolefin 35 gelingt die Darstellung von 37 und der zugehörigen Base 38 mit dem Grundgerüst der 1,7-Cyclo-cis-erythrinane.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120407
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  • 96
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    Synthetische Arbeiten in der Reihe der aromatischen Erythrina Alkaloide, XXIV. Über die Bromierungsprodukte von 15,16-Dimethoxy-cis-erythrinan-2,8-dion (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1126-1139 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of Aromatic Erythrina Alkaloids, XXIV. On the Products of Bromination of 15,16-Dimethoxy-cis-erythrinane-2,8-dioneBromination of 1 as well as hydrolysis of 5 (with inversion at C-l) yields the bromoketolactam 2. This can be converted back to 5, again with inversion. On reduction of 2 with sodium tetrahydridoborate, the bromohydrines 11-13 and the epoxide 17 are obtained. The epimeric bromoketolactam 6 cannot be isolated, but is an intermediate in the formation of 12 and 13. 2 reacts with potassium hydroxide in methanol or ethylene glycol to give the hydroxyacetals 18 and 19, respectively. From 1 the dibromoketones 24 and 25 were prepared which exhibit unusual spectral properties.
    Notes: Das Bromketolactam 2 wird aus 1 durch Bromierung oder aus 5 durch Hydrolyse unter Umkehrung der Konfiguration an C-l erhalten. Auch die entgegengesetzte Reaktion von 2 nach 5 verläuft unter Umkehr. Mit Natriumboranat liefert 2 die Bromhydrine 11, 12, 13 und das Epoxid 17. Bei der Bildung von 12 und 13 ist wieder das selbst nicht faßbare epimere Bromketolactam 6 Zwischenprodukt. Die Umsetzung von 2 mit Kaliumhydroxid in Methanol oder Ethylenglycol führt zu den Hydroxyacetalen 18 oder 19. Die aus 1 dargestellten Dibromketone 24 und 25 haben auffallende spektroskopische Eigenschaften.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120408
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  • 97
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    Methylschwefelpentafluorid und einige seiner Derivate (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1140-1146 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Methylsulfurpentafluoride and Some of its DerivativesMethylsulfurpentafluoride (5) was systematically synthesized, starting with SF5Cl and ketene. It is stable at room temperature against HF elimination. The reaction of SF5Cl and diketene gives compounds of the type SF5—CH2—X, but the title compound is not produced in this way.
    Notes: Methylschwefelpentafluorid (5) wurde systematisch synthetisiert, ausgehend von SF5Cl und Keten. Es ist bei Raumtemperatur stabil gegen HF-Eliminierung. Die Reaktion von SF5Cl und Diketen führt zu einer Vielzahl anderer Verbindungen des Typs SF5—CH2—X, in einfacher Weise jedoch nicht zur Titelverbindung.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120409
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  • 98
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    Synthesen biologisch wichtiger Kohlenhydrate, 20. N-Acetyl-1,4-di-O-acetyl-β-DL-vancosamin (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 3273-3281 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of Biologically Important Carbohydrates, 20. N-Acetyl-1,4-di-O-acetyl-β-DL-vancosamineClaisen rearrangement of 1-methyl-2-butenyl vinyl ether (3) yields trans-3-methyl-4-hexenal (4), the ethylene acetal 5 of which is aminated with selenium and chloramine T forming a mixture of the 3-methyl-3-tosylamino- (6) and 3-methyl-6-tosylamino derivatives 7. After detosylation of 6 and N-acetylation trans-3-acetylamino-3-methyl-4-hexenal ethylene acetal (9) is cis-hydroxylated to give 10/11. Cleavage of the protecting group at C-1 and peracetylation gives n-acetyl-1,4-di-O-acetyl-β-DL -vancosamine (13). The constitution of 13 is proved by mass spectrometry and the lyxo-configuration is assigned with high probability on the basis of 1 H NMR investigation *).
    Notes: Die Claisen-Umlagerung von (1-methyl-2-butenyl)-vinyl-ether (3)liefert trans-3-Methyl-4-hexenal(4), dessen Ethylenacetal 5 mit Selen und Chloramin-T zu den 3-Methyl-3-tosylamino-(6) und 3-Methl-6-tosylamino-Derivaten 7 aminiert wird. Nach Detosylierung von 6 und N-Acetylierung wird trans-3-Acetylamino-3-methyl-4-hexenal-ethylenacetal (9) zu 10/11 cis-hydroxyliert. Abspaltung der Schutzgruppe an C-1 und Peracetylierung liefert n-Acetyl-1,4-di-O-acetyl-β-DL-vancosamin (13), dessen Konstitution durch MS bewiesen und dessen lyxo-Konfiguration durch 1 H-NMR-Untersuchungen weitgehend gesichert wird *).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120922
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  • 99
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    Monomere Bis[dialkylphosphonium-bis(methylid)]-Komplexe des Nickels, Palladiums und Platins (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 3311-3317 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Monomeric Bis[dialkylphosphonium bis(methylide)] Complexes of Nickel, Palladium, and PlatinumThe reaction of bis(trimethylphosphane) complexes of NiCl2 and PdCl2 with the bulky ylide CH3[(CH3)3C]2P = CH2 in a molar ratio 1:4 leads to transylidation and formation of corresponding phosphonium salt and the new ylide chelates [(CH3)3C]2P(CH2)2M(CH2)2P[(CH3)3]2; M = Ni (1); M = Pd (2). In similar experiments with PtCl2, only the salt-like half-complex [(CH3)3C]2P(CH2)2Pt[P(CH3)3]2+Cl¯ (3) is obtained. However, the reaction of the lithiated ylide with (l,5-cyclooctadiene)PtCl2 yields the missing Pt analogue of the above type (4). Contrary to the results with Pd11, Ni11 reacts with 1 -methyl- l-methylene-λ.5-phospholane and -phosphorinane to give monomeric bis-chelates of the formula CH2]nP(CH2):Ni(CH2)2:P[CH2]n; n = 4 (5): n = 5 (6). The monomeric Structure was confirmed by 1H, 13C, 31P NMR, and mass spectra, and attributed to steric effects in the case of the tert-butyl compounds. The opening of the CPC chelate angle induced by the strained ring system of the cyclic ylides appears to favour pseudo-allyl type interactions with the nickel centre.
    Notes: Die Bis(trimethylphosphan)-Komplexe von NiCl2 und PdCl2 reagieren mit dem sterisch anspruchsvollen Ylid CH3[(CH3)3C]2P≡CH2 im Molverhältnis 1:4 unter Umylidierung zum zugehörigen Phosphoniumsalz und den neuen Ylid-Chelaten [(CH3)3C]2P(CH2)2M(CH2) P[2CH3)3 M] ≡Ni (1), M = Pd (2). Mit PtCl2 entsteht dagegen bei deràrtigen Ansätzen nur der salzartige Halbkomplex [(CH3)3C]2P(CH2)2Pt[P(CH3)3]2-;Cl+ (3). Die Reaktion des lithiierten Ylids mit (l,5-Cyclooctadien)PtCI2 liefert dagegen das fehlende Pt-Analoge des obigen Typs (4). - lm Gegensatz zu den Verhältnissen bei Pd11 ergibt NiII auch mit l-Methyl-l-methylen-λ5-phospholan und -phosphorinan monomere Doppelchelate der Formel [CH2]nP(CH2)2Ni(CH2)2P[CH2]n: n = 4(5), n = 5 (6). Die Monomerstruktur wurde durch 1H. 13C, 31P-NMR- und Massenspektren gesichert und bei den tert-Butyl-Verbindungen durch sterische Effekte gedeutet. Bei den cyclischen Yliden begünstigt die starke Winkelöffnung der Chelateinheit eine Pseudo-Allylwechselwirkung mit dem Nickelzentralatom.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791121004
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  • 100
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    Reaktivität von Metall-Metall-Bindungen. Wiederholte Schließung und Öffnung einer Fe - Co-Bindung durch Eliminierung und Addition (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 3390-3412 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactivity of Metal-Metal Bonds. Repeated Formation and Cleavage of a Fe - Co Bond by Elimination and AdditionIn arsenic-bridged dinuclear metal carbonyl complexes the sequence of formation and cleavage of the metal-metal bond by elimination of CO and addition of a phosphine ligand is repeatable. Starting from (CO)4Fe -AsMe2 - Co(CO)4 it can be performed four times in a row. The ligand which in each case is introduced at the cobalt atom can be transferred to the iron atom by isomerisation in complexes with and without metal-metal bonds. With Pme3 and P(OMe)3 as phosphines and up to the introduction of three ligands thus 44 different complexes are possible of which 35 were isolated (scheme 1). By side reactions or for the purpose of comparisons further complexes with chain-like arrangements of metal and P or As atoms were obtained. When four ligands are introduced the elimination/addition scheme reaches a natural limit since then phosphine elimination is preferred to CO elimination. The described sequences can be understood as basic patterns of catalytic activity by opening of metal-metal bonds.
    Notes: In arsenverbrückten Metallcarbonyl-Zweikernkomplexen ist die Sequenz von Bildung und Lösung der Metall-Metall-Bindung durch Eliminierung von CO und Addition eines Phosphanliganden wiederholbar. Ausgehend von (CO)4Fe-AsMe2-Co(CO)4 läßt sie sich viermal hintereinander durchführen. Der jeweils am Cobaltatom eingeführte Ligand kann in Komplexen mit und ohne Metall-Metall-Bindung durch Isomerisierung auch auf das Eisenatom übertragen werden. Mit PME3 und P(OMe)3 als Phosphanen sind so bis zur Einführung von drei Liganden 44 verschiedene Komplexe denkbar, von denen 35 isoliert wurden (Schema 1). Durch Nebenreaktionen bzw. zu Vergleichszwecken wurden weitere Komplexe mit kettenförmiger Anordnung von Metall- und P- bzw. As-Atomen erhalten. Nach der Einführung von vier Liganden findet das Eliminierungs/ Additions-Schema eine natürliche Grenze, da dann Phosphan-Eliminierung gegenüber der CO-Eliminierung bevorzugt wird. Die beschriebenen Sequenzen lassen sich als Grundmuster katalytischer Aktivität durch Öffnung von Metall-Metall-Bindungen verstehen.
    Additional Material: 6 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19791121008
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