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  • ddc:004
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  • 1
    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
    Format: application/pdf
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  • 2
    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
    Format: application/pdf
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  • 3
    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
    Format: application/pdf
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  • 4
    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
    Format: application/pdf
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  • 5
    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
    Format: application/pdf
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  • 6
    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
    Format: application/pdf
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  • 7
    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
    Format: application/pdf
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  • 8
    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
    Format: application/pdf
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  • 9
    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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  • 10
    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
    Format: application/pdf
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  • 11
    Publication Date: 2016-06-30
    Description: We study performance and scaling of the Berlin Quantum Chromodynamics Program (BQCD) on the SGI Altix 4700 at Leibniz Supercomputing Centre (LRZ). We employ different communication methods (MPI, MPI with two OpenMP threads per process, as well as the shmem library) and run the MPI version on the two types of nodes of that machine. For comparison with other machines we made performance measurements on an IBM p690 cluster and a Cray XT4.
    Keywords: ddc:004
    Language: English
    Type: reportzib , doc-type:preprint
    Format: application/pdf
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  • 12
    Publication Date: 2022-07-19
    Description: In dieser Arbeit wird eine Serie von Remeshing-Verfahren um die Berücksichtigung von nicht-mannigfaltigen Dreiecksvernetzungen und Merkmalskantenzügen erweitert. Die betrachteten Verfahren arbeiten im Wesentlichen lokal. Daher können die im Rahmen dieser Arbeit entwickelten Erweiterungen, die nicht-mannigfaltige Kantenzüge und Merkmalskantenzüge betreffen, separat beschrieben werden. Dabei wird ein Ansatz verfolgt, beide Arten von besonderen Kantenzügen aufgrund ihrer Gemeinsamkeiten einheitlich zu behandeln. Dieser besteht zum einen darin, eine Korrespondenz zwischen Kantenzügen auf der Eingabe- und der Ausgabefläche zu erhalten, indem die Remeshing-Operationen auf den Kantenzügen in entsprechend eingeschränkter Weise verwendet werden. Zum anderen wird beschrieben, wie die Abtastdichte der Kantenzüge dynamisch an die Abtastdichte der Umgebung angepasst werden kann, um für weitgehende Isotropie in der Nähe von Merkmalskantenzügen zu sorgen.
    Description: A unified approach for consistent remeshing of arbitrary non-manifold triangle meshes with additional user-defined feature lines is presented. The method is based on local operations only and produces meshes of high regularity and triangle quality while preserving the geometry as well as topology of the feature lines as well as the input mesh.
    Keywords: ddc:004
    Language: German
    Type: masterthesis , doc-type:masterThesis
    Format: application/pdf
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  • 13
    Publication Date: 2022-07-19
    Description: This work introduces a novel streamline seeding technique based on dual streamlines that are orthogonal to the vector field, instead of tangential. The greedy algorithm presented here produces a net of orthogonal streamlines that is iteratively refined resulting in good domain coverage and a high degree of continuity and uniformity. The algorithm is easy to implement and efficient, and it naturally extends to curved surfaces.
    Description: In dieser Arbeit wird eine neue Strategie zur Platzierung von Stromlinien vorgestellt. Hierzu werden zusätzliche duale Stromlinien verwendet, die --im Gegensatz zur üblichen Definition-- orthogonal zum Vektorfeld verlaufen. Der vorgestellte Greedy-Algorithmus berechnet ein Netz aus orthogonalen Stromlinien, welches iterativ verfeinert wird, was zu einer guten Abdeckung der Domäne und einer gleichmäßigen Verteilung der Stromlinien führt. Es handelt sich um einen einfach zu implementierenden und effizienten Algorithmus, der direkt auf gekrümmten Oberflächen anwendbar ist.
    Keywords: ddc:004
    Language: English
    Type: reportzib , doc-type:preprint
    Format: application/pdf
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  • 14
    Publication Date: 2020-12-11
    Description: In dieser Diplomarbeit wird untersucht, wie auf der Basis von Literaturreferenzen ein Zitationsgraph durch ein automatisches Verfahren aufgebaut werden kann. Zur Lösung des Problems werden Probabilistische Relationale Modelle herangezogen. Eine problemspezifische Erweiterung des Modells ermöglicht es, dass bestehende Unsicherheiten im Zitationsgraphen mit Hilfe eines Inferenzverfahrens aufgelöst werden können. Zur Evaluierung des Verfahren werden Experimente auf dem Cora-Datensatz durchgeführt.
    Keywords: ddc:004
    Language: German
    Type: masterthesis , doc-type:masterThesis
    Format: application/pdf
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  • 15
    Publication Date: 2016-06-30
    Description: Die Diplomarbeit präsentiert ein Transaktionsverfahren für strukturierte Overlay-Netzwerke, das an die Erfordernisse verteilter Informationssysteme mit relationalem Datenmodell angepasst ist. Insbesondere wird der Einsatz von Transaktionen für verteilte Wikis betrachtet, die moderne Funktionalitäten, wie Metadaten und zusätzliche Indexe für die Navigation, unterstützen. Konsistenz und Dauerhaftigkeit der gespeicherten Daten erfordert die Behandlung von Knotenausfällen. Die Arbeit schlägt dafür das Zellenmodell vor: Das Overlay wird aus replizierten Zustandsmaschinen gebildet, um Verfügbarkeit zu gewährleisten. Das Transaktionsverfahren baut darauf auf und verwendet Two-Phase-Commit mit Fehlererkennung und Widerherstellung von ausgefallenen Transaktionsmanagern. Anwendungen wird eine Auswahl an pessimistischen und hybrid-optimistischen Nebenläufigkeitskontrollverfahren geboten, die die Minimierung von Latenzeffekten und die schnelle Ausführung von Nur-Lese-Transaktionen ermöglichen. Für die Beispielanwendung Wiki wird der erforderliche Pseudocode angegeben und die verschiedenen Nebenläufigkeitskontrollverfahren hinsichtlich ihrer Nachrichtenkomplexität verglichen.
    Description: The diploma thesis presents a transaction processing scheme for structured overlay networks and uses it to develop a distributed Wiki application based on a relational data model. The Wiki supports rich metadata and additional indexes for navigation purposes. Ensuring consistency and durability requires handling of node failures. Such failures are masked by providing high availability of nodes. This in turn is achieved by constructing the overlay from replicated state machines (cell model). Atomicity is realized using two phase commit with additional support for failure detection and restoration of the transaction manager. The developed transaction processing scheme provides the application with a mixture of pessimistic, hybrid optimistic and multiversioning concurrency control techniques to minimize the impact of replication on latency and optimize for read operations. The pseudocode of the relevant Wiki functions is presented and the different concurrency control techniques are evaluated in terms of message complexity.
    Keywords: ddc:004
    Language: German
    Type: masterthesis , doc-type:masterThesis
    Format: application/pdf
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  • 16
    Publication Date: 2016-06-30
    Description: Die Arbeit präsentiert ein Transaktionsverfahren für strukturierte Overlay-Netzwerke, das an die Erfordernisse verteilter Informationssysteme mit relationalem Datenmodell angepasst ist. Insbesondere wird der Einsatz von Transaktionen für verteilte Wikis betrachtet, die moderne Funktionalitäten, wie Metadaten und zusätzliche Indexe für die Navigation, unterstützen. Konsistenz und Dauerhaftigkeit der gespeicherten Daten erfordert die Behandlung von Knotenausfällen. Die Arbeit schlägt dafür das Zellenmodell vor: Das Overlay wird aus replizierten Zustandsmaschinen gebildet, um Verfügbarkeit zu gewährleisten. Das Transaktionsverfahren baut darauf auf und verwendet Two-Phase-Commit mit Fehlererkennung und Widerherstellung von ausgefallenen Transaktionsmanagern. Anwendungen wird eine Auswahl an pessimistischen und hybrid-optimistischen Nebenläufigkeitskontrollverfahren geboten, die die Minimierung von Latenzeffekten und die schnelle Ausführung von Nur-Lese-Transaktionen ermöglichen. Für die Beispielanwendung Wiki wird der erforderliche Pseudocode angegeben und die verschiedenen Nebenläufigkeitskontrollverfahren hinsichtlich ihrer Nachrichtenkomplexität verglichen.
    Description: The report presents a transaction processing scheme for structured overlay networks and uses it to develop a distributed Wiki application based on a relational data model. The Wiki supports rich metadata and additional indexes for navigation purposes. Ensuring consistency and durability requires handling of node failures. Such failures are masked by providing high availability of nodes. This in turn is achieved by constructing the overlay from replicated state machines (cell model). Atomicity is realized using two phase commit with additional support for failure detection and restoration of the transaction manager. The developed transaction processing scheme provides the application with a mixture of pessimistic, hybrid optimistic and multiversioning concurrency control techniques to minimize the impact of replication on latency and optimize for read operations. The pseudocode of the relevant Wiki functions is presented and the different concurrency control techniques are evaluated in terms of message complexit
    Keywords: ddc:004
    Language: German
    Type: reportzib , doc-type:preprint
    Format: application/pdf
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  • 17
    Publication Date: 2016-06-30
    Description: Berlin als Stadtstaat ist Kommune und Land der Bundesrepublik zugleich und Standort vieler renommier-ter Wissenschafts- und Kultureinrichtungen. In enger Zusammenarbeit der Wissenschaftseinrichtungen mit dem IT-Dienstleistungszentrum Berlin (ITDZ, ehemals Landesbetrieb für Informationstechnik), der für die Behörden Berlins zuständigen Einrichtung, wurde seit 1993 ein landeseigenes Glasfasernetz mit einer derzeitigen Länge von 856 km Glasfaserkabel (je Kabel bis zu 144 Einzelfasern) zur gemeinsamen Nutzung von Wissenschaft und Verwaltung errichtet und weiter ausgebaut. 1994 erfolgte der offizielle Start des Berliner Wissenschaftsnetzes BRAIN (Berlin Research Area Information Network), als durch einen Beschluss des Senats von Berlin die Nutzung des landeseigenen Glasfasernetzes durch die Wissen-schaftseinrichtungen festgeschrieben wurde. Bereits 1995 wurden durch die Wissenschaftseinrichtungen auf diesem Glasfasernetz die ersten sieben Anschlüsse in ATM-Technik (Classical BRAIN-ATM) in Betrieb genommen, 1999 wurden anschließend auch erste Strecken in Ethernet-Technik (Classical BRAIN-GE) betrieben. Diese heterogenen Netze mit unterschiedlichen Netzgeräten wurden dezentral von den Netzadministratoren der beteiligten Einrichtungen nach globalen Absprachen betreut. Die dezentrale Administration erschwerte das Management und die Erweiterungen der Gesamtnetze. Basierend auf den vorliegenden Erfahrungen vereinbarten die Berliner Wissenschaftseinrichtungen, ein technisch neues Verbundnetz in Gigabit-Ethernet-Technik mit einheitlichen Geräten und einem zentralen Netzwerkmana-gement aufzubauen und zu betreiben. Seit November 2003 betreibt BRAIN auf dem landeseignen Glasfasernetz ein auf MPLS-Technik basie-rendes Gigabit-Ethernet-Netz, das „BRAIN-Verbundnetz“, mit den Diensten LAN-to-LAN-Kopplung der Einrichtungen, regionaler IP-Verkehr, Übergang zum Verwaltungsnetz und WiN-Backup. Das BRAIN-Verbundnetz löste die dezentral betreuten Vorläufernetze komplett ab. Von den derzeit 27 BRAIN-Teilnehmern nutzen 24 Einrichtungen an 53 in der Stadt verteilten Standorten die Dienste des BRAIN-Verbundnetzes, 18 Standorte sind mit 1000 Mbit/s und 35 Standorte mit 100 Mbit/s angeschlossen. Für verteilte Standorte einer Einrichtung besteht zudem die Möglichkeit, diese über dedizierte Fasern oder Bandbreiten miteinander zu vernetzen. Seit dem 2. Quartal 2007 wird im Rahmen eines Pilotprojekts der Nutzen eines zentral gemanagten Fibre Channel-Netzwerks "BRAIN-SAN" ermittelt, um Möglichkeiten einer verteilten Datenhaltung der Berliner Hochschulen und wissenschaftlichen Einrichtungen zu schaf-fen. Zusätzlich zu den vorgenannten Diensten nutzt der DFN-Verein die BRAIN-Struktur für die Verbindun-gen der X-WiN-Kernnetzknoten in Berlin und Potsdam untereinander und für Zugangsleitungen zu den Anwendern. Mit Stand 2007 nutzt das Berliner Wissenschaftsnetz BRAIN vom landeigenen Glasfasernetz 2100 km Einzelfasern und verbindet insgesamt 43 Einrichtungen (BRAIN-Teilnehmer und DFN-Anwender) aus Wissenschaft, Bildung und Kultur mit 129 Standorten. Der Betrieb von BRAIN wird im wesentlichen durch seine Nutzer finanziert. Das Land Berlin trägt aller-dings pauschal die überwiegenden Kosten für die Wartung des Glasfasernetzes, soweit es vom ITDZ be-reit gestellt wird. Zentrales Planungs- und Steuerungsorgan für BRAIN ist die von der Senatsverwaltung für Bildung, Wis-senschaft und Forschung eingerichtete BRAIN-Planungsgruppe. Sie besteht aus Mitarbeitern der Rechen-zentren der drei Berliner Universitäten und des ZIB. Nach außen wird BRAIN in rechtlicher und wirtschaftlicher Hinsicht treuhänderisch vom ZIB vertreten, die BRAIN-Geschäftsstelle befindet sich ebenfalls im ZIB.
    Description: Berlin as a city state is both local authority and federal state of the Federal Republic, as well as a location of many renowned institutions of research and culture. In close cooperation of the institutions of research with the IT service centre Berlin (ITDZ, the former Landesbetrieb für Informationstechnik) - which is the appropriate facility for the authorities of Berlin - a glass fibre network of a total extension of 856 kilome-tres of fibre optics (144 fibres each cable optic) for the common use of research and administration has been established and advanced since 1993. In 1994, when a resolution of the Senate of Berlin laid down the use of the appropriate fibre networks by the research facilities, this was the official beginning of the Berlin Research Area Information Network (BRAIN). The first seven interfaces in this fibre network in ATM technology (Classical BRAIN-ATM) were already established by the research facilities in 1995. In 1999, first systems run in Ethernet technology (Classical BRAIN-GE). These heterogeneous networks with different interfaces have been supported locally by the network administrators of the research facili-ties following global agreements. Management and advancement of the overall networks were encum-bered by these local administrations. Based on the existing experience, Berlin's research facilities agreed on the building and advancement of a technically new integrated network in gigabit Ethernet technology with standardised facilities and a centrally managed network. Since November 2003 the Berlin Research Area Information Network established a Gigabit Ethernet - called “BRAIN Integrated Network” - based on MPLS technology, including LAN to LAN linking of the facilities, local IP traffic, interface to the administration's network and WIN back-up. This BRAIN Inte-grated Network has completely replaced the locally administered predecessor networks. 24 of 27 BRAIN participants use the services of the BRAIN Integrated Network on 53 locations spread all over the city. 18 locations are connected with 1000 Mbit/s and 35 locations with 100 Mbit/s. Moreover, spread locations of a single facility have the possibililty to communicate by dedicated fibres or bandwidths. From the 2nd quarter 2007 within the scope of a pilot scheme, the advantage of a centrally administered fibre channel network "BRAIN-SAN" will be determined in order to accomplish possibilities of a spread data manage-ment of Berlin's universities and research facilities. In addition to the aforementioned services the DFN association makes use of BRAIN's structure for the connection of the X-WiN-core network nodes in Berlin and Potsdam und for access pathways to the us-ers. As from 2007, Berlin's research network BRAIN uses 2100 kilometres of single fibres from the country's fibre glass network and connects a total of 43 facilities (BRAIN participants and DFN users) from re-search, education and culture with 129 locations. The operations of BRAIN are funded basically by its users. However, the country of Berlin bears most of the costs for the maintenance of the glass fibre network, as far as it is provided by ITDZ. Central planning and steering body for BRAIN is the BRAIN planning group, which has been arranged by the administration of the Senatsverwaltung für Bildung, Wissenschaft und Forschung. It consists of staff from the computing centres of Berlin's three universities and of ZIB. BRAIN is represented legally and economically on a trust basis by the ZIB, where the BRAIN office is located also.
    Keywords: ddc:004
    Language: German
    Type: reportzib , doc-type:preprint
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  • 18
    Publication Date: 2022-07-19
    Description: For medical diagnosis, visualization, and model-based therapy planning three-dimensional geometric reconstructions of individual anatomical structures are often indispensable. Computer-assisted, model-based planning procedures typically cover specific modifications of “virtual anatomy” as well as numeric simulations of associated phenomena, like e.g. mechanical loads, fluid dynamics, or diffusion processes, in order to evaluate a potential therapeutic outcome. Since internal anatomical structures cannot be measured optically or mechanically in vivo, three-dimensional reconstruction of tomographic image data remains the method of choice. In this work the process chain of individual anatomy reconstruction is described which consists of segmentation of medical image data, geometrical reconstruction of all relevant tissue interfaces, up to the generation of geometric approximations (boundary surfaces and volumetric meshes) of three-dimensional anatomy being suited for finite element analysis. All results presented herein are generated with amira ® – a highly interactive software system for 3D data analysis, visualization and geometry reconstruction.
    Keywords: ddc:004
    Language: English
    Type: reportzib , doc-type:preprint
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  • 19
    Publication Date: 2022-07-19
    Description: This work introduces novel internal and external memory algorithms for computing voxel skeletons of massive voxel objects with complex network-like architecture and for converting these voxel skeletons to piecewise linear geometry, that is triangle meshes and piecewise straight lines. The presented techniques help to tackle the challenge of visualizing and analyzing 3d images of increasing size and complexity, which are becoming more and more important in, for example, biological and medical research. Section 2.3.1 contributes to the theoretical foundations of thinning algorithms with a discussion of homotopic thinning in the grid cell model. The grid cell model explicitly represents a cell complex built of faces, edges, and vertices shared between voxels. A characterization of pairs of cells to be deleted is much simpler than characterizations of simple voxels were before. The grid cell model resolves topologically unclear voxel configurations at junctions and locked voxel configurations causing, for example, interior voxels in sets of non-simple voxels. A general conclusion is that the grid cell model is superior to indecomposable voxels for algorithms that need detailed control of topology. Section 2.3.2 introduces a noise-insensitive measure based on the geodesic distance along the boundary to compute two-dimensional skeletons. The measure is able to retain thin object structures if they are geometrically important while ignoring noise on the object's boundary. This combination of properties is not known of other measures. The measure is also used to guide erosion in a thinning process from the boundary towards lines centered within plate-like structures. Geodesic distance based quantities seem to be well suited to robustly identify one- and two-dimensional skeletons. Chapter 6 applies the method to visualization of bone micro-architecture. Chapter 3 describes a novel geometry generation scheme for representing voxel skeletons, which retracts voxel skeletons to piecewise linear geometry per dual cube. The generated triangle meshes and graphs provide a link to geometry processing and efficient rendering of voxel skeletons. The scheme creates non-closed surfaces with boundaries, which contain fewer triangles than a representation of voxel skeletons using closed surfaces like small cubes or iso-surfaces. A conclusion is that thinking specifically about voxel skeleton configurations instead of generic voxel configurations helps to deal with the topological implications. The geometry generation is one foundation of the applications presented in Chapter 6. Chapter 5 presents a novel external memory algorithm for distance ordered homotopic thinning. The presented method extends known algorithms for computing chamfer distance transformations and thinning to execute I/O-efficiently when input is larger than the available main memory. The applied block-wise decomposition schemes are quite simple. Yet it was necessary to carefully analyze effects of block boundaries to devise globally correct external memory variants of known algorithms. In general, doing so is superior to naive block-wise processing ignoring boundary effects. Chapter 6 applies the algorithms in a novel method based on confocal microscopy for quantitative study of micro-vascular networks in the field of microcirculation.
    Description: Die vorliegende Arbeit führt I/O-effiziente Algorithmen und Standard-Algorithmen zur Berechnung von Voxel-Skeletten aus großen Voxel-Objekten mit komplexer, netzwerkartiger Struktur und zur Umwandlung solcher Voxel-Skelette in stückweise-lineare Geometrie ein. Die vorgestellten Techniken werden zur Visualisierung und Analyse komplexer drei-dimensionaler Bilddaten, beispielsweise aus Biologie und Medizin, eingesetzt. Abschnitt 2.3.1 leistet mit der Diskussion von topologischem Thinning im Grid-Cell-Modell einen Beitrag zu den theoretischen Grundlagen von Thinning-Algorithmen. Im Grid-Cell-Modell wird ein Voxel-Objekt als Zellkomplex dargestellt, der aus den Ecken, Kanten, Flächen und den eingeschlossenen Volumina der Voxel gebildet wird. Topologisch unklare Situationen an Verzweigungen und blockierte Voxel-Kombinationen werden aufgelöst. Die Charakterisierung von Zellpaaren, die im Thinning-Prozess entfernt werden dürfen, ist einfacher als bekannte Charakterisierungen von so genannten "Simple Voxels". Eine wesentliche Schlussfolgerung ist, dass das Grid-Cell-Modell atomaren Voxeln überlegen ist, wenn Algorithmen detaillierte Kontrolle über Topologie benötigen. Abschnitt 2.3.2 präsentiert ein rauschunempfindliches Maß, das den geodätischen Abstand entlang der Oberfläche verwendet, um zweidimensionale Skelette zu berechnen, welche dünne, aber geometrisch bedeutsame, Strukturen des Objekts rauschunempfindlich abbilden. Das Maß wird im weiteren mit Thinning kombiniert, um die Erosion von Voxeln auf Linien zuzusteuern, die zentriert in plattenförmigen Strukturen liegen. Maße, die auf dem geodätischen Abstand aufbauen, scheinen sehr geeignet zu sein, um ein- und zwei-dimensionale Skelette bei vorhandenem Rauschen zu identifizieren. Eine theoretische Begründung für diese Beobachtung steht noch aus. In Abschnitt 6 werden die diskutierten Methoden zur Visualisierung von Knochenfeinstruktur eingesetzt. Abschnitt 3 beschreibt eine Methode, um Voxel-Skelette durch kontrollierte Retraktion in eine stückweise-lineare geometrische Darstellung umzuwandeln, die als Eingabe für Geometrieverarbeitung und effizientes Rendering von Voxel-Skeletten dient. Es zeigt sich, dass eine detaillierte Betrachtung der topologischen Eigenschaften eines Voxel-Skeletts einer Betrachtung von allgemeinen Voxel-Konfigurationen für die Umwandlung zu einer geometrischen Darstellung überlegen ist. Die diskutierte Methode bildet die Grundlage für die Anwendungen, die in Abschnitt 6 diskutiert werden. Abschnitt 5 führt einen I/O-effizienten Algorithmus für Thinning ein. Die vorgestellte Methode erweitert bekannte Algorithmen zur Berechung von Chamfer-Distanztransformationen und Thinning so, dass diese effizient ausführbar sind, wenn die Eingabedaten den verfügbaren Hauptspeicher übersteigen. Der Einfluss der Blockgrenzen auf die Algorithmen wurde analysiert, um global korrekte Ergebnisse sicherzustellen. Eine detaillierte Analyse ist einer naiven Zerlegung, die die Einflüsse von Blockgrenzen vernachlässigt, überlegen. In Abschnitt 6 wird, aufbauend auf den I/O-effizienten Algorithmen, ein Verfahren zur quantitativen Analyse von Mikrogefäßnetzwerken diskutiert.
    Keywords: ddc:004
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 20
    Publication Date: 2022-07-19
    Description: One crucial step in virtual drug design is the identification of new lead structures with respect to a pharmacological target molecule. The search for new lead structures is often done with the help of a pharmacophore, which carries the essential structural as well as physico-chemical properties that a molecule needs to have in order to bind to the target molecule. In the absence of the target molecule, such a pharmacophore can be established by comparison of a set of active compounds. In order to identify their common features,a multiple alignment of all or most of the active compounds is necessary. Moreover, since the “outer shape” of the molecules plays a major role in the interaction between drug and target, an alignment algorithm aiming at the identification of common binding properties needs to consider the molecule’s “outer shape”, which can be approximated by the solvent excluded surface. In this thesis, we present a new approach to molecular surface alignment based on a discrete representation of shape as well as physico-chemical properties by points distributed on the solvent excluded surface. We propose a new method to distribute points regularly on a surface w.r.t. a smoothly varying point density given on that surface. Since the point distribution algorithm is not restricted to molecular surfaces, it might also be of interest for other applications. For the computation of pairwise surface alignments, we extend an existing point matching scheme to surface points, and we develop an efficient data structure speeding up the computation by a factor of three. Moreover, we present an approach to compute multiple alignments from pairwise alignments, which is able to handle a large number of surface points. All algorithms are evaluated on two sets of molecules: eight thermolysin inhibitors and seven HIV-1 protease inhibitors. Finally, we compare the results obtained from surface alignment with the results obtained by applying an atom alignment approach.
    Description: Die Identifizierung neuer Leitstrukturen (lead structures) zur Entwicklung optimierter Wirkstoffe ist ein äußerst wichtiger Schritt in der virtuellen Wirkstoffentwicklung (virtual drug design). Die Suche nach neuen Leitstrukturen wird oft mit Hilfe eines Pharmakophor-Modells durchgeführt, welches die wichtigsten strukturellen wie auch physiko-chemischen Eigenschaften eines bindenden Moleküls in sich vereint. Ist das Zielmolekül (target) nicht bekannt, kann das Pharmakophor-Modell mit Hilfe des Vergleiches aktiver Moleküle erstellt werden. Hier ist insbesondere die gleichzeitige Überlagerung (multiple alignment) aller oder nahezu aller Moleküle notwendig. Da bei der Interaktion zweier Moleküle die "äußere Form" der Moleküle eine besondere Rolle spielt, sollte diese von jedem Überlagerungsalgorithmus, der sich mit der Identifizierung von Bindungseigenschaften befasst, berücksichtigt werden. Dabei kann die "äußere Form" durch eine bestimmte Art von molekularer Oberfläche approximiert werden, die man als solvent excluded surface bezeichnet. In dieser Arbeit stellen wir einen neuen Ansatz zur Überlagerung molekularer Oberflächen dar, der auf einer diskreten Repräsentation sowohl der Form als auch der molekularen Eigenschaften mittels Punkten beruht. Um die Punkte auf der molekularen Oberfläche möglichst regulär entsprechend einer gegebenen Punktdichte zu verteilen, entwickeln wir eine neue Methode. Diese Methode ist nicht auf Moleküloberflächen beschränkt und könnte daher auch für andere Anwendungen von Interesse sein. Basierend auf einem bekannten Point-Matching Verfahren entwickeln wir einen Point-Matching Algorithmus für Oberflächenpunkte. Dazu erarbeiten wir u.a. eine effiziente Datenstruktur, die den Algorithmus um einen Faktor von drei beschleunigt. Darüberhinaus stellen wir einen Ansatz vor, der Mehrfachüberlagerungen (multiple alignments) aus paarweisen Überlagerungen berechnet. Die Herausforderung besteht hierbei vor allem in der großen Anzahl von Punkten, die berücksichtigt werden muss. Die vorgestellten Algorithmen werden an zwei Gruppen von Molekülen evaluiert, wobei die erste Gruppe aus acht Thermolysin Inhibitoren besteht, die zweite aus sieben HIV-1 Protease Inhibitoren. Darüberhinaus vergleichen wir die Ergebnisse der Oberflächenüberlagerung mit denen einer Atommittelpunktüberlagerung.
    Keywords: ddc:004
    Language: English
    Type: doctoralthesis , doc-type:doctoralThesis
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  • 21
    ISSN: 1530-0358
    Keywords: Desmoids ; Genetics ; Chemotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract PURPOSE: The aim of this study was to describe the natural history and management of surgically unresectable intra-abdominal desmoid tumors in two patients with Gardner's syndrome from two unrelated families, where each had failed on conventional therapy. METHODS: Two patients with Gardner's syndrome were placed on a chemotherapy regimen which included doxorubicin (90 mg/m2) and dacarbazine (900 mg/m2) in divided doses over four days of continuous infusion. Their progress on chemotherapy was assessed by abdominal computerized tomography and laparoscopy. RESULTS: The computerized abdominal tomography scans proved difficult to interpret because of adhesions and matted small bowel resulting from the patients original colectomies. These findings made it difficult to differentiate postoperative changes from residual desmoid tumor. Second-look laparotomy in such patients was contraindicated as this may predispose to further desmoid production. Laparoscopy disclosed a complete response to this chemotherapy. Nevertheless, we had an iatrogenic small bowel perforation in one of these patients. Each patient showed a complete response to chemotherapy. CONCLUSION: Surgical resection remains the first-line treatment of intra-abdominal desmoid tumors. However, doxorubicin/ dacarbazine chemotherapy on a clinical trial basis may be indicated in patients whose intra-abdominal desmoid is unresectable, or who have failed to respond to treatment with hormones (tamoxifen, Toremifene), steroids (prednisone), and nonsteroidal anti-inflammatory agents (Clinoril®; Merck & Co., Inc., West Point, PA).
    Type of Medium: Electronic Resource
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  • 22
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 50 (1994), S. 429-437 
    ISSN: 1420-9071
    Keywords: Genetics ; ecology ; DNA-transfer ; conjugation ; transformation ; transduction ; transposons ; dormant cells ; epilithon ; microbial colonisation ; symbiosis ; virus resistance ; biosafety ; release of genes ; insults to humanity ; evolution ; biodiversity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Genetic ecology is the extension of our modern knowledge in molecular genetics to studies of viability, gene expression and gene movements in natural environments like soils, aquifers and digestive tracts. In such milieux, the horizontal transfer of plasmid-borne genes between phylogenetically distant species has already been found to be much more frequent than had been expected from laboratory experience. For the study of exchanges involving chromosomally-located genes, more has to be learned about the behaviour of transposons in such environments. The results expected from studies in genetic ecology are relevant for considerations of evolution, biodiversity and biosafety. The role of this new field of research in restoring popular confidence in science and in its biotechnological applications is stressed.
    Type of Medium: Electronic Resource
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  • 23
    ISSN: 1437-160X
    Keywords: Systemic lupus erythematosus ; Recombinant U1-nRNP proteins ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To investigate a possible involvement of HLA-class II alleles in the genetic predisposition for the formation of anti-U1-nRNP antibody in systemic lupus erythematosus (SLE), genomic DNA of 178 patients was typed for the DRB1, DQA1 and DQB1 alleles using a polymerase chain reaction (PCR) and non-radioactive-oligonucleotide typing. Antibodies against recombinant U1-nRNP proteins (U1-A- U1-C-and 70K-protein) were determined by ELISA. Anti-U1-C antibody was found in 26 (14.7%), anti-U1-A in 34 (19.2%) and anti-70K in 17 (9.6%) patients. A joint occurrence was observed for these antibodies against the recombinant U1-nRNP proteins: anti-U1-C and anti-U1-A antibodies occurred together more frequently than alone and than together with anti-U1-70K antibodies. The frequency of DRB1 * 04 was slightly increased in the patients with anti-U1-C as compared to the patients without anti-U1-C (P〈0.05, Pcorr=n.s., RR=2.4). The DQA1 * 0301 allele, which is in linkage disequilibrium with DRB1 * 04, is found more frequently in anti-U1-C-positive than in antibody-negative patients. The DQB1 * 0303 allele, detected in 12 of 176 SLE patients, was absent in the patients with any of the antibodies against the U1-nRNP proteins. All these deviations may be due to chance alone. We concluded that the presence of antibodies against recombinant U1-nRNP proteins was not significantly associated with any HLA DRB1, DQA1 and DQB1 allele in our group of SLE patients.
    Type of Medium: Electronic Resource
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  • 24
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 72 (1994), S. 409-413 
    ISSN: 1432-1440
    Keywords: Myotonic dystrophy ; Limb girdle muscular dystrophy ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A family is reported in which a 29-year-old woman showed the clinical features of myotonic dystrophy while her 26-year-old brother presented with the clinical picture of limb girdle syndrome. In the affected female, direct genetic testing for the specific myotonic dystrophy mutation on chromosome 19 revealed abnormal expansion of a repeat unit containing the three nucleotides cytosine, thymine, and guanine (CTG) — typical for myotonic dystrophy — while her diseased brother displayed two normal alleles. This supports the hypothesis of the extremely rare occurrence of two clinically and genetically different myopathies in one family. Genetic analysis of six other family members showed that the father of the diseased siblings as well as all of his three brothers and sisters had a pathological CTG repeat expansion, and that the other two family members tested had a normal allelic pattern. The number of CTG repeats in the diseased women was approximately tenfold higher than in her asymptomatic relatives who revealed an abnormal allelic pattern. The increase in CTG repeats with transmission to a subsequent generation in this family was paralleled by a dramatic increase in the severity of myotonic dystrophy.
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  • 25
    ISSN: 1432-0533
    Keywords: Key words     Primitive neuroepithelial tumor ; Desmoplastic small cell tumor ; Brain tumor of infancy ; Immunocytochemistry ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract      We describe a case of a desmoplastic brain tumor which was initially resected from the right fronto-temporal region in a 2 year-old boy. This nodular, calcified tumor was vascularized by the internal carotid artery and the middle meningeal artery branches. Grossly, it contained several mucoid cysts. Light microscopy showed cords or nests of small cuboidal cells surrounded by a loose connective tissue and desmoplasic areas containing fibers and spindle cells. The cuboidal cells expressed epithelial, neuronal and neuroendocrine markers. Some foci of spindle cells showed glial differentiation. The tumor recurred 16 months later and displayed some characteristics of the small cell neuroepithelial component, mitoses being conspicuous. Electron microscopy revealed undifferentiated clear cells, some containing neurosecretory granules. Karyotyping demonstrated the following formula: 〈 15 〉 46, t(8;11) (q13; q11). The chromosome 11 breakpoint was different from that described in Ewing's sarcoma. This isolated translocation has not been previously reported to our knowledge. These unusual features lead us to report this case and to discuss its pathogenesis.
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  • 26
    ISSN: 1432-0533
    Keywords: Amyotrophic lateral sclerosis ; Neuropathology ; Posterior column involvement ; Genetics ; Superoxide dismutase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Several missense mutations within exons 1, 2, 4 and 5 of the gene for Cu/Zn-binding superoxide dismutase (SOD1) have been discovered to be involved in the development of chromosome 21q-linked familial amyotrophic lateral sclerosis (FALS). We describe here an autopsied patient with FALS, in whom we have recently identified a novel missense mutation in exon 1 of the SOD1 gene. The neuropathological findings were compatible with those described previously in patients with FALS with posterior column involvement. This suggests that mutations of the SOD1 gene may be responsible for this form of FALS.
    Type of Medium: Electronic Resource
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  • 27
    ISSN: 1432-0533
    Keywords: Key words: Amyotrophic lateral sclerosis ; Neuropathology ; Posterior column involvement ; Genetics ; Superoxide dismutase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Several missense mutations within exons 1, 2, 4 and 5 of the gene for Cu/Zn-binding superoxide dismutase (SOD1) have been discovered to be involved in the development of chromosome 21q-linked familial amyotrophic lateral sclerosis (FALS). We describe here an autopsied patient with FALS, in whom we have recently identified a novel missense mutation in exon 1 of the SOD1 gene. The neuropathological findings were compatible with those described previously in patients with FALS with posterior column involvement. This suggests that mutations of the SOD1 gene may be responsible for this form of FALS.
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  • 28
    ISSN: 1432-0428
    Keywords: Genetics ; diabetes mellitus ; mitochondria ; maternal ; deafness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Non-insulin-dependent diabetes mellitus (NIDDM) has a strong genetic component and maternal factors have recently been implicated in disease inheritance. The mitochondrial myopathies are a group of diseases which often show maternal inheritance as a result of mtDNA defects; some patients have impaired glucose tolerance. Occasional families with maternally inherited diabetes and deafness associated with a deletion or point mutation of mtDNA have been reported. To assess the importance of mitochondrial gene defects in NIDDM, 150 unrelated diabetic subjects from Wales, UK and 68 unrelated patients with diabetes and at least one affected sibling from England, UK were studied. Southern blot analysis did not show any large mtDNA deletions or duplications. One patient had a mutation in the mitochondrial tRNAleu(UUR) gene at bp 3243. This mutation is commonly associated with the syndrome of mitochondrial encephalomyopathy, lactic acidosis and stroke like episodes (MELAS). Study of this patient and his siblings showed a distinct form of late-onset diabetes associated with nerve deafness but no clinical features of the MELAS syndrome. No diabetic subject was shown to have the mtDNA mutation at position 8344 (tRNAlys) which has previously been described in the syndrome of mitochondrial encephalomyopathy and red-ragged fibres (MERRF). The role of other mitochondrial gene defects in diabetes and the pathophysiological basis of glucose intolerance in patients with the MELAS mutation requires further elucidation.
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  • 29
    Electronic Resource
    Electronic Resource
    Springer
    Journal of biomedical science 1 (1994), S. 201-203 
    ISSN: 1423-0127
    Keywords: Hypertension ; Eicosanoid ; Rat ; Genetics ; Kidney
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The present paper reviews the evidence for a possible involvement of renal eicosanoids in the pathophysiology of high blood pressure in genetically hypertensive rats of the Lyon strain. Both in vivo and in vitro experiments suggest that an increased ability to synthesize the vasoconstrictor prostaglandin H2 and/or thromboxane A2 in renal vessels (1) acts as an autocrine amplifier of pressor agents and (2) may contribute to resetting the pressure natriuresis curve which is a prerequisite for the development and maintenance of hypertension.
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  • 30
    ISSN: 1432-0428
    Keywords: Genetics ; haplotype ; HLA-A ; HLA-DQ ; HLA-DR ; tumour necrosis factor ; diabetes mellitus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In Finland the haplotype A2, Cw1, B56, DR4, DQ8 is the third most common haplotype in insulin-dependent diabetic (IDDM) patients and has the highest haplotype-specific absolute risk for IDDM. Cw1, B56, DR4, DQ8 haplotypes containing HLA-A alleles other than A2 are infrequent in the population and are not associated with IDDM. Comparison of the A2 and non-A2 haplotypes at the DNA level showed that they were identical at HLA-B,-DR, and -DQ loci. Evidence that class I alleles confer susceptibility to IDDM was obtained from the two HLA-C, -B, -DR and -DQ haplotypes most frequently found in IDDM patients in Finland. A24, A3 and A2 on the Cw3, B62, DR4, DQ8 haplotype, and A28, A2 and A1 on the Cw7, B8, DR3, DQ2 were all found to be associated with IDDM. In Finland these seven haplotypes, including A2, Cw1, B56, DR4, DQ8, account for 33% of diabetic haplotypes and 10.3% of non-diabetic haplotypes (p〈0.00001). The contribution of the class I region to IDDM susceptibility was also apparent in those IDDM patients lacking the disease-predisposing class II alleles. Significantly more non-DR3/non-DR4 IDDM patients (47 of 55) possessed two of the IDDM-associated HLA-A alleles compared to non-DR3/non-DR4 control subjects (40 of 58; p=0.038). Moreover, IDDM patients confirmed by oligotyping as unable to form a ‘diabetes-susceptibility’ DQ heterodimer, tended to possess two diabetes-associated HLA-A alleles (12 of 13) compared to control subjects (12 of 20; p=0.056).
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  • 31
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    Pediatric cardiology 15 (1994), S. 198-200 
    ISSN: 1432-1971
    Keywords: Subaortic stenosis ; Congenital heart disease ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The first case of multiple family members with discrete subaortic membrane and no other congenital defects is presented. One family member presents with findings suggesting a forme fruste of this disease. Increased surveillance of family members of individuals with discrete subaortic membrane is warranted, as the clinical findings of mild subaortic obstruction may be indistinguishable from those of an innocent flow murmur.
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  • 32
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    Pediatric cardiology 15 (1994), S. 201-203 
    ISSN: 1432-1971
    Keywords: Tricuspid atresia ; Tricuspid hypoplasia ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Occurrence of a similar cardiac malformation in multiple family members has been reported for many lesions. Neither tricuspid atresia nor tricuspid annular hypoplasia and tricuspid atresia and one case of tricuspid annular hypoplasia with an atrial septal defect in siblings. The findings in this family suggest an autosomal recessive pattern of inheritance for abnormal tricuspid valve morphogenesis.
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  • 33
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    Sexual plant reproduction 7 (1994), S. 290-296 
    ISSN: 1432-2145
    Keywords: Secale cereale ; Polyembryony ; Chromosome mosaics ; Rye ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have obtained one plant regenerated from rye tissue culture which showed a high percentage of polyembryonic seeds in its progeny. The mutation inducing the development of extra embryos is also influencing erroneous cell division, mitosis and meiosis. The genetic analysis indicated that the aptitude for polyembryonic seed formation is a heritable trait controlled by a dominant gene. However, for expression of the phenotype the female parent should have a specific cytoplasm.
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  • 34
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    European journal of pediatrics 153 (1994), S. 372-377 
    ISSN: 1432-1076
    Keywords: Epilepsy ; Absences ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Clinical and EEG family data of 140 cases with early childhood epilepsy with absences are presented. The aim of the study was to evaluate, whether the occurrence of generalized tonic clonic seizures (GTCS) as a presenting symptom might correlate with family data, i.e. whether there are indications of heterogeneity. One hundred and forty cases were selected from the epilepsy family data base of the Neuropaediatric Department. The selection parameter was epilepsy with absences manifesting between the 1 st and 5th year of age. The incidence of seizures was evaluated in siblings, parents and parents' siblings. EEG records were available from 103 parents and 106 siblings. The analysis supports the assumption of heterogeneity within early childhood absence epilepsy. Parents and their sibs of cases manifesting with GTCS had seizures twice as often than parents and their sibs in the non-GTCS group. In the affected relatives of the GTCS group early onset GTCS prevailed, whereas in the relatives of the non-GTCS group absences were found more frequently. The EEG of relatives showed elevated incidences of spikes and waves and photosensitivity in both groups, indicating common genetic factors. In parents of the non-GTCS group, however, EEG pathology was significantly more frequent than in parents of the GTCS group. Comparing EEG pathology in parents with seizure risk in siblings, evidence for maternal preponderance in transmission of the seizure liability was found. Mothers' EEG seems to be the best predictor of the seizure risk in probands' siblings. Early childhood epilepsy with absences can be regarded as an intermediate type, showing overlap with early onset GTCS and myoclonic astatic epilepsy on the one side and with childhood absence epilepsy on the other.
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  • 35
    ISSN: 1432-1459
    Keywords: Multiple sclerosis Epidemiology ; Immigrants Environment ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The incidence and prevalence of multiple sclerosis (MS) were compared, controlling for age, in native-born Israelis of different origins and in immigrants to Israel. This comparison was carried out in two populations, countrywide and in Jerusalem. In the countrywide population, ascertainment was based mainly on hospitalizations; it included 252 patients who were native-born and 150 who had immigrated from Africa-Asia (AA immigrants). The 89 MS patients of Jerusalem also included patients diagnosed in outpatient clinics. In native-born Israelis whose father was born in Europe-America (I-EA), the incidence and prevalence of MS were found to be as high as or even higher than that found previously in immigrants from Europe-America. Among native-born Israelis whose father was born in Africa or Asia (I-AA), the yearly age-adjusted incidence and prevalence rates were found to be 1.4- to 1.8-fold higher than among AA immigrants, pointing to environmental factors. The incidence and prevalence rates in the I-EA were 1.2- to 1.6-fold higher than in the I-AA, pointing to genetic factors. These results seem to point to both environmental and genetic factors in the aetiology of MS. Further research is needed, however, to disentangle the genetic factors from possible environmental differences in the two ethnic groups.
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  • 36
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    European archives of psychiatry and clinical neuroscience 244 (1994), S. 138-140 
    ISSN: 1433-8491
    Keywords: Parity ; Genetics ; Diathesis-stress model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract As part of a follow-up and family study of post-partum psychoses, this episode of illness being the first leading to psychiatric hospitalisation, patients with puerperal episodes (PE) and nonpuerperal episodes (NPE) of illness in the long-term course (n=79) were compared to patients with PE only (n=40). Few differences were found. Relatives of patients with PE only had a lower morbidity risk for functional psychoses than relatives of patients with PE and NPE. A favourable course of illness in the presence of a low genetic predisposition may be expected, according to the diathesis-stress model of functional psychoses.
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  • 37
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    Journal of neurology 241 (1994), S. 487-491 
    ISSN: 1432-1459
    Keywords: Juvenile absence epilepsy ; Valproate ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Fifteen patients aged 11–25 years (mean 15.37, SD 3.89) suffering from juvenile absence epilepsy are presented. Only 3 (20%) had absences (AS) as the only seizure type, 12 (80%) had associated generalized tonic-clinic seizures (GTCS) and in the remaining 3 with absences and GTCS there was also sporadic myoclonus. We found a higher frequency of AS in our patients by clinical history and video-EEG than has been previously reported. In our patients the mean age of onset in years was 11.4, SD 1.24 for AS, 13.12, SD 2.31 for GTCS and 12.5, SD 2.18 for myoclonus. The correct diagnosis was not made on referrals for any of the patients. It took an average of 3–5.5 years from the onset of the AS (range: 6–120 months) and 2 years from the occurrence of GTCS (average: 1–72 months) to make the correct diagnosis and institute proper treatment, which was valproic acid (VPA). The GTCS were controlled in all patients whereas AS continued in 6 (40%), but to a significantly lesser degree. The frequency and the duration of the GTCS before the start of VPA treatment seemed to have an adverse effect on AS control. We documented no circadian rhythm in either AS or the GTCS, except in 2 patients who had AS and GTCS mainly when they awoke in the morning. The sample size was too small to perform a proper genetic study, though a positive history of epilepsies of mixed types was obtained in 35.7% of the parents and the siblings of the probands.
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  • 38
    ISSN: 1432-2242
    Keywords: Maize ; Restriction fragment length polymorphisms (RFLPs) ; Qualitative and quantitative inheritance ; Plant breeding ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Restriction fragment length polymorphisms (RFLPs) and one morphological marker were used to investigate quantitative trait loci (QTL) for morphological and physiological traits evaluated on 150 F2∶3 maize (Zea mays L.) lines derived from the cross of elite U.S. Corn Belt inbreds Mo17 and H99. F2∶3 lines were grown in a replicated experiment and evaluated for plant and ear heights and flowering traits. QTL were identified for each trait, and genetic effects were determined. Estimated gene action for the flowering traits was predominantly overdominance. Both parents contributed toward increased values for anthesis and silk emergence. QTL for increased plant and ear heights were usually contributed by the taller parent, Mo17. Estimated gene action for these traits was mainly partial to overdominance. QTL for plant height were located in the vicinity of loci defined by alleles with qualitative effects on plant height.
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  • 39
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    Theoretical and applied genetics 89 (1994), S. 959-963 
    ISSN: 1432-2242
    Keywords: Sugarcane ; Polyploidy ; Genetics ; Evolution ; Breeding ; DNA markers ; Arbitrarily primed PCR ; RAPD markers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Recent work has revealed random chromosome pairing and assortment in Saccharum spontaneum L., the most widely distributed, and morphologically and cytologically variable of the species of Saccharum. This conclusion was based on the analysis of a segregating population from across between S. spontaneum ‘SES 208’ and a spontaneously-doubled haploid of itself, derived from anther culture. To determine whether polysomic inheritance is common in Saccharum and whether it is observed in a typical biparental cross, we studied chromosome pairing and assortment in 44 progeny of a cross between euploid, meiotically regular, 2n=80 forms of Saccharum officinarum ‘LA Purple’ and Saccharum robustum ‘ Mol 5829’. Papuan 2n=80 forms of S. robustum have been suggested as the immediate progenitor species for cultivated sugarcane (S. officinarum). A total of 738 loci in LA Purple and 720 loci in Mol 5829 were amplified and typed in the progeny by arbitrarily primed PCR using 45 primers. Fifty and 33 single-dose polymorphisms were identified in the S. officinarum and S. robustum genomes, respectively (χ 2 at 98%). Linkage analysis of single-dose polymorphisms in both genomes revealed linkages in repulsion and coupling phases. In the S. officinarum genome, a map hypothesis gave 7 linkage groups with 17 linked and 33 unlinked markers. Four of 13 pairwise linkages were in repulsion phase and 9 were in coupling phase. In the S. robustum genome, a map hypothesis gave 5 linkage groups, defined by 12 markers, with 21 markers unlinked, and 2 of 9 pairwise linkages were in repulsion phase. Therefore, complete polysomic inheritance was not observed in either species, suggesting that chromosomal behavior is different from that observed by linkage analysis of over 500 markers in the S. spontaneum map. Implications of this finding for evolution and breeding are discussed.
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  • 40
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    Theoretical and applied genetics 89 (1994), S. 313-317 
    ISSN: 1432-2242
    Keywords: Genetics ; Rice ; Phosphorousefficiency ; Diallel analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The inheritance of phosphorous (P) — deficiency tolerance in rice was investigated by a sevenparent diallel. The parent materials involved were four P-efficient (IR20, IR54, IR28, and Mahsuri), one moderately P-efficient (TN1), and two P-inefficient (IR31406333-1 and IR34686-179-1-2-1), genotypes. Relative tilering ability (RTA) under P-deficient and P-supplemented soil conditions was the parameter used in determining the tolerance level of the different genotypes. Diallel graph analysis revealed that tolerant parents have an excess of recessive genes, while moderate and susceptible parents possess more dominant genes. Genetic-component analysis suggested that both additive and dominance gene effects are involved in the inheritance of P-deficiency tolerance in rice. The trait exhibited over doiminance as confirmed by the graphical analysis. Narrow-sense heritability of the trait was moderate (0.50) and environmental effects were low. Both the general combining ability (GCA) and the specific combining ability (SCA) were significant, but GCA was more prevalent than SCA. Tolerant parents exhibited a high GCA whereas susceptibles have a very poor GCA, suggesting that tolerant parents were mostly enriched in additive genes and susceptible parents in non-additive genes. Crosses involving two high general combiners showed low SCA effects whereas crosses between poor general combiners manifested highly-significant SCA values.
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  • 41
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    Theoretical and applied genetics 88 (1994), S. 754-758 
    ISSN: 1432-2242
    Keywords: Potato breeding ; Potato leaf roll virus ; Virus resistance ; Major gene resistance ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The concentration of potato leaf roll virus (PLRV), as measured by a quantitative enzyme-linked immunosorbent assay, in the foliage of potato plants (Solanum tuberosum) of cv ‘Maris Piper’ with secondary infection was 2900 ng/g leaf, whereas in clones G7445(1) and G7032(5) it was 180 ng/g leaf and 120 ng/g leaf, respectively. To examine the genetic control of resistance to PLRV multiplication, reciprocal crosses were made between the susceptible cultivar ‘Maris Piper’ and the two resistant clones, and the three parents were selfed. Seedling progenies of these families were grown to generate tubers of individual genotypes (clones). Clonally propagated plants were graft-inoculated, and their daughter tubers were collected and used to grow plants with secondary infection in which PLRV concentration was estimated. The expression of resistance to PLRV multiplication had a bimodal distribution in progenies from crosses between ‘Maris Piper’ and either resistant clone, and also in progeny from selfing the resistant parents, with genotypes segregating into high and low virus titre groups. Only the progeny obtained from selfing ‘Maris Piper’ did not segregate, all genotypes being susceptible to PLRV multiplication. The pattern of segregation obtained from these progenies fits more closely with the genetical hypothesis that resistance to PLRV multiplication is controlled by two unlinked dominant complementary genes, both of which are required for resistance, than with the simpler hypothesis that resistance is conferred by a single dominant gene, as published previously.
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  • 42
    ISSN: 1432-2242
    Keywords: Breeding ; Helminthosporium turcicum ; RFLP ; QTLs ; Disease-resistance ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract RFLPs were used to investigate components of host-plant response to Exserohilum turcicum in 150 unselected F2∶3 lines of a B52/Mo17 maize population. Following inoculation with spore suspensions of the pathogen (race 0), components of disease development were measured and then quantitative trait mapping was performed to identify the location and effects of quantitative trait loci (QTLs) determining host-plant response. Components of interest were the average number of lesions per leaf, the average percent leaf tissue diseased (severity) and the average size of lesions (cm2). Based on a LOD threshold of 2.31 (P〈0.05), the number of lesions appears to be associated with QTLs on chromosomes 1S, 3L, 5S. Severity was associated with analogous regions and, in addition, QTLs on chromosomes 7L and 8L. Most QTLs, for either of these two components, involve additive gene action and partial dominance or overdominance. In contrast, lesion size was associated with QTLs on chromosomes 7L and 5L; recessive gene action may be involved at 7L.
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  • 43
    ISSN: 1432-2242
    Keywords: Genetics ; Disease resistance ; Monocots
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An F2 oat population was produced by crossing the diploid (n=7) species Avena strigosa (CI 3815) with A. wiestii (CI 1994), resistant and susceptible, respectively, to 40 isolates of Puccinia coronata, the causal agent of crown rust. Eighty-eight F2 individuals were used to construct an RFLP linkage map representing the A genome of cultivated hexaploid oat. Two hundred and eight RFLP loci have been placed into 10 linkage groups. This map covers 2416 cM, with an average of 12 cM between RFLP loci. Eighty-eight F3 lines, derived from F2 individuals used to construct the map, were screened for resistance to 9 isolates of P. coronata. One locus, Pca, was found to confer a dominant resistance phenotype to isolates 203, 258, 263, 264B, 290, 298, 325A, and 345. Pca also conferred resistance to isolate 276; however, an unlinked second gene may also be involved.
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  • 44
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    Behavioral ecology and sociobiology 34 (1994), S. 117-409 
    ISSN: 1432-0762
    Keywords: Social insects ; Apis mellifera ; Division of labor ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Variability exists among worker honey bees for components of division of labor. These components are of two types, those that affect foraging behavior and those that affect life-history characteristics of workers. Variable foraging behavior components are: the probability that foraging workers collect (1) pollen only; (2) nectar only; and (3) pollen and nectar on the same trip. Life history components are: (1) the age the workers initiate foraging behavior; (2) the length of the foraging life of a worker; and (3) worker length of life. We show how these components may interact to change the social organization of honey bee colonies and the lifetime foraging productivity of individual workers. Selection acting on foraging behavior components may result in changes in the proportion of workers collecting pollen and nectar. Selection acting on life-history components may affect the size of the foraging population and the distribution of workers between within nest and foraging activities. We suggest that these components define possible sociogenic “pathways” through which colony-level natural selection can change social organization. These pathways may be analogous to developmental pathways in the morphogenesis of individual organisms because small changes in behavioral or life history components of individual workers may lead to major changes in the organizational structure of colonies.
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  • 45
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    Behavioral ecology and sociobiology 35 (1994), S. 99-107 
    ISSN: 1432-0762
    Keywords: Key words Apis mellifera ; Genetics ; Drone production ; Allozymes ; Reproductive conflict
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previously we reported that there are subfamily differences in drone production in queenless honey bee colonies, but these biases are not always explained by subfamily differences in oviposition behavior. Here we determine whether these puzzling results are best explained by either inadequate sampling of the laying worker population or reproductive conflict among workers resulting in differential treatment of eggs and larvae. Using colonies composed of workers from electrophoretically distinct subfamilies, we collected samples of adult bees engaged in the following behavior: “true” egg laying, “false” egg laying, indeterminate egg laying, egg cannibalism, or nursing (contact with larvae). We also collected samples of drone brood at four different ages: 0 to 2.5-h-old eggs, 0 to 24-h-old eggs, 3 to 8-day-old larvae, and 9 to 14-day-old larvae and pupae. Allozyme analyses revealed significant subfamily differences in the likelihood of exhibiting egg laying, egg cannibalism, and nursing behavior, as well as significant subfamily differences in drone production. There were no subfamily differences among the different types of laying workers collected from each colony, suggesting that discrepancies between subfamily biases in egg-laying behavior and drone production are not due to inadequate sampling of the laying worker population. Subfamily biases in drone brood production within a colony changed significantly with brood age. Laying workers had significantly more developed ovaries than either egg cannibals or nurses, establishing a physiological correlate for the observed behavioral genetic differences. These results suggest there is reproductive conflict among subfamilies and individuals within queenless colonies of honey bees. The implications of these results for the evolution of reproductive conflict, in both queenright and queenless contexts, are discussed.
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  • 46
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    Behavioral ecology and sociobiology 34 (1994), S. 125-137 
    ISSN: 1432-0762
    Keywords: Social insects ; Apis mellifera ; Division of labor ; Genetics ; Nepotism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Three experiments were performed to determine whether brood care in honey bee colonies is influenced by colony genetic structure and by social context. In experiment 1, there were significant genotypic biases in the relative likelihood of rearing queens or workers, based on observations of individually labeled workers of known age belonging to two visually distinguishable subfamilies. In experiment 2, no genotypic biases in the relative likelihood of rearing drones or workers was detected, in the same colonies that were used in experiment 1. In experiment 3, there again were significant genotypic differences in the likelihood of rearing queens or workers, based on electrophoretic analyses of workers from a set of colonies with allozyme subfamily markers. There also was an overall significant trend for colonies to show greater subfamily differences in queen rearing when the queens were sisters (half- and super-sisters) rather than unrelated, but these differences were not consistent from trial to trial for some colonies. Results of experiments 1 and 3 demonstrate genotypic differences in queen rearing, which has been reported previously based on more limited behavioral observations. Results from all three experiments suggest that genotypic differences in brood care are influenced by social context and may be more pronounced when workers have a theoretical opportunity to practice nepotism. Finally, we failed to detect persistent interindividual differences in bees from either subfamily in the tendency to rear queen brood, using two different statistical tests. This indicates that the probability of queen rearing was influenced by genotypic differences but not by the effect of prior queen-rearing experience. These results suggest that subfamilies within a colony can specialize on a particular task, such as queen rearing, without individual workers performing that task for extended periods of time.
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  • 47
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    Behavioral ecology and sociobiology 35 (1994), S. 99-107 
    ISSN: 1432-0762
    Keywords: Apis mellifera ; Genetics ; Drone production ; Allozymes ; Reproductive conflict
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previously we reported that there are subfamily differences in drone production in queenless honey bee colonies, but these biases are not always explained by subfamily differences in oviposition behavior. Here we determine whether these puzzling results are best explained by either inadequate sampling of the laying worker population or reproductive conflict among workers resulting in differential treatment of eggs and larvae. Using colonies composed of workers from electrophoretically distinct subfamilies, we collected samples of adult bees engaged in the following behavior: “true” egg laying, “false” egg laying, indeterminate egg laying, egg cannibalism, or nursing (contact with larvae). We also collected samples of drone brood at four different ages: 0 to 2.5-h-old eggs, 0 to 24-h-old eggs, 3 to 8-day-old larvae, and 9 to 14-day-old larvae and pupae. Allozyme analyses revealed significant subfamily differences in the likelihood of exhibiting egg laying, egg cannibalism, and nursing behavior, as well as significant subfamily differences in drone production. There were no subfamily differences among the different types of laying workers collected from each colony, suggesting that discrepancies between subfamily biases in egg-laying behavior and drone production are not due to inadequate sampling of the laying worker population. Subfamily biases in drone brood production within a colony changed significantly with brood age. Laying workers had significantly more developed ovaries than either egg cannibals or nurses, establishing a physiological correlate for the observed behavioral genetic differences. These results suggest there is reproductive conflict among subfamilies and individuals within queenless colonies of honey bees. The implications of these results for the evolution of reproductive conflict, in both queenright and queenless contexts, are discussed.
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  • 48
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    Metabolic brain disease 9 (1994), S. 105-131 
    ISSN: 1573-7365
    Keywords: Alcoholism ; Genetics ; Endorphins ; Enkephalins ; Dynorphins ; Opioid ; Receptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract At the present time alcoholism is recognized as a metabolic disease exhibiting the clinical features of craving for alcohol, loss of control over drinking, tolerance and physical dependence on alcohol, while both epidemiological and experimental studies have demonstrated that genetic factors may be important in determining whether an individual has a high or low vulnerability to develop alcoholism. Evidence also indicates that alcoholism is not characterized by a single gene single allele inheritance. Instead it seems that multiple genes and environmental factors interact to increase or decrease an individual's vulnerability to become an alcoholic. Current research is aimed at investigating whether certain behavioral, physiological and biochemical markers are highly associated with the incidence of alcoholism. Among the biochemical markers currently under investigation is the endogenous opioid system and its implication in mediating the reinforcing effects of ethanol. It is the objective of this manuscript to review current research on: (a) the interactions of ethanol with the endogenous opioid system at the molecular level; (b) the existence of genetically determined differences in the response of the endogenous opioid system to ethanol between subjects at high and low risk for excessive ethanol consumption, as well as between lines of animals showing preference or aversion for ethanol solutions; (c) the decrease of alcohol consumption following pretreatment with opioid antagonists; and (d) the possible use of specific opioid receptor antagonists together with behavioral therapy to modify drinking behavior, to control craving and to prevent relapse.
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  • 49
    ISSN: 1617-4623
    Keywords: Gene regulation ; Ribozyme ; npt-gene ; Transgenic tobacco ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A chimeric gene encoding a ribozyme under the control of the cauliflower mosaic virus (CaMV) 35S promoter was introduced into transgenic tobacco plants. In vivo activity of this ribozyme, which was designed to cleave npt mRNA, was previously demonstrated by transient expression assays in plant protoplasts. The ribozyme gene was transferred into transgenic tobacco plants expressing an rbcS-npt chimeric gene as an indicator. Five double transformants out of sixteen exhibited a reduction in the amount of active NPT enzyme. To measure the amount of ribozyme produced, in the absence of its target, the ribozyme and target genes were separated by genetic segregation. The steady-state concentrations of ribozyme and target RNA were shown to be similar in the resulting single transformants. Direct evidence for a correlation between reduced npt gene expression and ribozyme expression was provided by crossing a plant containing only the ribozyme gene with a transgenic plant expressing the npt gene under control of the 35S promoter, i.e. the same promoter used to direct ribozyme expression. The expression of npt was reduced in all progeny containing both transgenes. Both steady-state levels of npt mRNA and amounts of active NPT enzyme are decreased. In addition, our data indicate that, at least in stable transformants, a large excess of ribozyme over target is not a prerequisite for achieving a significant reduction in target gene expression.
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  • 50
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    European journal of epidemiology 10 (1994), S. 317-324 
    ISSN: 1573-7284
    Keywords: Epidemiology ; Genetics ; Oral clefts ; Registers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Epidemiological and genetic variables for oral clefts were analysed for the years 1981–1989 in a case-control study of congenital malformations in the Emilia Romagna, Veneto, and Friuli regions, and in the Trento and Bolzano hospitals. Birth prevalence for all cases of cleft lip with or without cleft palate (CL(P)) was 8.2 per 10,000 births, and that for cleft palate only (CP) was 6.1 per 10,000. Coexisting abnormalities were found in 23% of CL(P) cases and in 43% of CP. No clusters in time or space were detected. For isolated clefts, a predominance of males among CL(P) and of females among CP was found; epilepsy was the only maternal risk factor correlated with clefts, and an association between clefting and consanguinity was found. Empirical recurrence risks were calculated in both isolated CL(P) and CP.
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  • 51
    ISSN: 0009-2940
    Keywords: Norpinanes, preparation ; Carbocations, classical and nonclassical ; Neighbouring group participation ; Halonium ions ; Migratory aptitudes in carbocations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrophilic Additions to the Bicyclo[1.1.0]butane System of Tricyclo[4.1.0.02,7]heptane Derivatives: Halogen ElectrophilesThe known reactions of 8,8-dibromotetracyclo[5.1.0.02,4.03,5]octane (3a) and homobenzvalene (7) with pyridinium bromide perbromide and iodine, respectively, were carried out in the presence of tetra-n-butylammonium chloride. The formation of the chloro-substituted norpinane derivatives 6a and 9 is evidence for cationic intermediates. The same mechanism is operative in the reaction of pyridinium bromide perbromide with the dichlorotetracyclooctane 3b, which was prepared from 7 and dichlorocarbene. On exposure of tricyclo[4.1.0.02,7]heptane (1) to N-bromosuccinimide in acetone/water/triethylamine, the bromonorpinanol 22, the bromonorcaranols 23, and cyclohex-1-ene-1-carboxaldehyde (24) were obtained. On the basis of the steric course and thermodynamic considerations, the cationic intermediates generated in the above reactions by attack of the electrophiles at the bicyclobutane systems are assigned the halonium ion structure 38 and the nonclassical structures 34 and 35, respectively. Elemental bromine and iodine converted the phenyltricycloheptane 10 into the respective diastereomeric norpinanes 11 and 12, which were transformed smoothly into the diastereomeric methyl ethers 13 and 14 by treatment with sodium methoxide in methanol. The reactions of 10 with pyridinium bromide perbromide in pyridine, cyanogen bromide in the presence of aluminium trichloride, and N-bromosuccinimide in acetone/water gave rise to norpinane derivatives, i.e. the pyridinium salt 15, the nitrile 16, and the alcohol 18, respectively. In the case of cyanogen iodide in acetonitrile, the solvent participated in the process to yield the 2-(norpinylimino)propionitriles 17. Corresponding to the configurations of the products, the attack of a halogen electrophile at 10 leads to classical 6-phenyl-6-norpinyl cations 41, which may be approached by nucleophiles from the two possible faces. As origin for the low tendency of the cations 33-35 and 41 to rearrange to norcaryl cations, the electronegativity of the halogen atoms is suggested. The reduced migratory aptitude of a CHHal relative to a CH2 group results from its electron deficiency and from the decreased stability of 7-halo-2-norcaryl relative to the parent 2-norcaryl cations. The chlorophenyltricycloheptane 25 was prepared from 10 and treated with aqueous sulfuric acid to give the norpinanol 27. Formed by protonation of the bicyclobutane system of 25, the cationic precursor of 27 shows a behaviour similar to that of cations 41.
    Additional Material: 2 Tab.
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  • 52
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 433-436 
    ISSN: 0009-2940
    Keywords: Epoxidation ; Dioxirane, dimethyl- ; Benzofurans, 2-methyl- ; Benzofuran epoxides ; Quinone methides ; Photoisomerization ; Chromenes ; 3-Benzofuranones ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dimethyldioxirane oxidation of the 3-substituted 2-methylbenzofurans 1 [1a: 3(E)-styryl, 1b: 3-acetoxy, 1c: 3-(tert-butyldimethylsilyloxy)] is reported. Only quinone methide 3a, none of the benzofuran epoxides 2a-c, could be detected by 1H- and 13C-NMR spectroscopy at low temperature (-30°C), which on photoisomerization led to chromene 7a. The benzofuran-3-ones 5b, c and the α-diketone 6c are presumably formed by thermal isomerization of the transient benzofuran epoxides 2b, c and quinone methide 3c.
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  • 53
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 581-584 
    ISSN: 0009-2940
    Keywords: Fullerenes ; [3 + 2] Cycloadditions ; Nitrile oxides ; Isoxazoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Functionalization of C60 with Nitrile Oxides to 4,5-Dihydroisoxazoles and Their Structure DeterminationCycloadducts 3 of nitrile oxides 2 with C60 (1) are synthesized and isolated. The cycloadducts are characterized by 13C-NMR spectroscopy and high-resolution FAB mass spectrometry. X-ray structure determination of the 3-(9-anthryl)-4,5-dihydroisoxazole derivative 3a of C60 with CS2 included in the crystals is achieved at 173 K without disorder problems.
    Additional Material: 3 Ill.
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  • 54
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 565-579 
    ISSN: 0009-2940
    Keywords: Li enolates, of 6-trifluoromethyl-1,3-dioxan-4-one ; Alkylation, of Li enolates ; Michael additions, to 1,3-dioxin-4-ones, to nitroolefins ; Benzylation, abnormal products ; Methyl 3-hydroxy-3-trifluoromethyl propionates ; 1,3-Dioxanones, 2,5,6-trisubstituted ; Conformation, of 1,3-dioxan-4-ones ; Twist-boat conformation, of cis,cis- and trans,trans-2.5,6-trisubstituted 1,3-dioxan-4-ones ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of Enantiomerically Pure 4,4,4-Trifluoro-3-hydroxy-butanoic Acid Derivatives, Branched in the 2- or 3-Position, from 6-Trifluoromethyl-1,3-dioxan- and -dioxin-4-onesEnantiomerically pure 3-hydroxy-3-trifluoromethyl-propionic acid and esters, substituted in the 2- or 3-position, are prepared (13 examples) from (R)- or (S)-4,4,4-trifluoro-3-hydroxy-butanoic acid. Key intermediates are the 2-t-butyl-6-trifluoromethyl-1,3-dioxan- and -dioxin-4-ones. The Li enolate of the cis-dioxanone is generated with t-BuLi and reacts with electrophiles (alkyl halides, aldehydes, imines, nitroolefins, Br2, I2) with predominant formation of trans,trans-2,5,6-trisubstituted dioxanones (9 examples). Elimination of HBr from the 5-Br-substituted dioxanone gives the (R)- or (S)-dioxinone, a chiral derivative of 4,4,4-trifluoro-3-oxo-butanoic acid (trifluoro-acetoacetate). Michael additions of cuprates or of CuCl-doped Grignard reagents to the dioxinone produce 6,6-disubstituted dioxanones (10 examples) bearing a CF3 group in the 6-position. In most cases this addition is highly diastereoselective, with the new substituent winding up in the trans position. There are, however, surprising exceptions, such as the product formed with benzylmagnesium chloride which is an abnormal adduct with a p-quinoid structure (26) and with the newly introduced group in the cis position with respect to the t-Bu group. The structures of four trisubstituted dioxanones bearing CF3 groups are determined by X-ray crystal structure analysis (Figure 1, Table 1), one of them including the absolute configuration (by anomalous diffraction). Besides the well-known sofa, a twist-boat conformation of dioxanones appears to be favorable. The solution conformations of the different types of CF3-substituted dioxanones are derived from Nuclear Overhauser NMR measurements and compared with the crystal structures (Figure 3).
    Additional Material: 3 Ill.
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  • 55
    ISSN: 0009-2940
    Keywords: Isocyanide-bridged metal complexes ; Metal complexes as ligands ; N-Protonation (alkylation, metalation) ; Heteropentanuclear metal complexes ; Diisocyanide bridges ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Coordination Chemistry with the Complex Chelating Ligands [{Fe2Cp2(CO)3)2{CN[CH2]n NC}] (n = 2, 3). Heteropentanuclear “Supercomplexes” with μ5-Diisocyanide BridgesHerrn Professor Dr. O. J. Scherer zum 60. Geburtstag gewidmet.The tetranuclear complexes [(Fe2Cp2(CO)2(μ-CO)}2(μ4-CN[CH2]nNC}] [n = 2 (2), 3 (3)] act as bidentate chelating ligands towards the Lewis-acidic metal halides MnCl2, MnBr2, FeCl2, CoCl2, NiCl2, NiBr2, CuCl2, CuBr2, ZnCl2, ZnI2, CdCl2, CdI2, HgCl2, the chloro complexes [MCl2-(NCPh)2] (M = Pd, Pt), Zn(OAc)2 · H2O, and [Mo(CO)4(η-NBD)] (NBD = 2,5-norbornadiene) to give a total of 22 pentanuclear “supercomplexes” ,6-21, which have been characterized by elemental analyses and IR and NMR (1H, 13C) spectra. Reaction of 2 with [Ni(COD)2] in CH2Cl2 gave only rise to the dichloronickel(II) species 9a. Very remarkably, the pentairon complex [(Fe2Cp2(CO)2(μ-CO)2(μ5-CN(CH2)2-NC)}]FeCl2 (7) also formed spontaneously (!) when 2 was refluxed in chloroform for several hours. The X-ray structure analysis of [{Fe2Cp2(CO)2(μ-CO))2{μ5-CN(CH2)2NC}]CdI2 (14b) confirms the twofold μ3-(C,C,N) bridging mode of a diisocyanide ligand in a cis/cis-anti-configurated [Fe2]2Cd pentanuclear system of crystallographic C2 symmetry.
    Additional Material: 1 Ill.
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  • 56
    ISSN: 0009-2940
    Keywords: Germane, optically active ; Biotransformation, stereoselective ; Transesterification, enzymatic ; Porcine liver esterase ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of ( - )-(Acetoxymethyl)(hydroxymethyl)methyl(phenyl)germane [( - )-MePhGe(CH2OAc)(CH2OH)] by an Esterase-Catalyzed Transesterification: the First Enzymatic Synthesis of an Optically Active GermaneThe prochiral germane MePhGe(CH2OH)2 (1) was synthesized by a six-step synthesis starting from GeCl4 (3) [3 → Cl2Ge(CH2Cl)2 (4) → Ph2Ge(CH2Cl)2 (5) → (CF3S(O)2O)PhGe(CH2Cl)2 (6) → MePhGe(CH2Cl)2 (7) → MePhGe(CH2OAc)2 (8) → 1]. Reaction of 1 with Ac2O/NEt3 (molar ratio 1: Ac2O = 1:1) gave the racemic germane rac-MePhGe(CH2OAc)(CH2OH) (rac-2). Stereoselective transesterification of 1 with vinyl acetate (acetate source and solvent), catalyzed by immobilized porcine liver esterase (PLE; E.C.-3.1.1.1), yielded the optically active germane ( - )-MePhGe(CH2OAc)(CH2OH) [( - )-2] (yield 57%, enantiomeric purity 50% ee).
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  • 57
    ISSN: 0009-2940
    Keywords: Platinum complexes, five-coordinate ; Nitrosyl complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title complex has been prepared in 36% yield by reaction of [NBu4]2[trans-Pt(C6Cl5)2Cl2] with NOClO4 (1:1) in CH2Cl2. The anion exhibits an almost tetragonal-pyramidal geometry (X-ray analysis), the platinum atom being virtually located in the basal plane and the NO ligand occupying the apical position. The Pt—N—O unit is bent [119.5(8)°].
    Additional Material: 1 Ill.
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  • 58
    ISSN: 0009-2940
    Keywords: Dimethyldioxirane ; 3-Phenyl-2-phenylsulfonyloxaziridine ; Titanium enolates ; Enantioselective hydroxylation ; α-Hydroxy carbonyl compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stereoselective oxidation of the optically active titanium enolate complexes 2 of propiophenone by dimethyldioxirane (3) (as acetone solution) and 3-Phenyl-2-phenylsulfonyloxaziridine (4) has been investigated. The chiral titanium enolates 2 were synthesized by the reaction of the lithium enolate of propiophenone and the respective optically active chlorotitanate complexes 1. For 3 as oxidant, the stereoselectivity of the α hydroxylation strongly depends on the substitution pattern at the central titanium atom and reached for the best case, namely 2e, an enantiomeric excess (ee) of 63%. Solvent and temperature exhibited only small effects on the stereoselectivity. Compound 4 as oxidant gave lower enantiomeric excesses than 3.
    Additional Material: 1 Tab.
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  • 59
    ISSN: 0009-2940
    Keywords: C—C Bond cleavage, kinetics of ; Heats of formation ; Radicals, stability of ; Capto-dative effect ; Geminal substituents, energetic interaction of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituent Effects on the Strength of C—C Bonds, 14[1].  -  Kinetic and Thermodynamic Stability of 2,3-Bis(dialkylamino)-1,4-diketones  -  Energy of Stabilization of α-Dialkylamino α-Carbonylalkyl Radicals with Capto-dative SubstituentsProf. Dr. H.-G. Viehe zum 65. Geburtstag gewidmet.The equilibrium constants and rate constants for the dissociation of the 2,3-bis(dialkylamino)-1,4-diketone diastereomers meso- and DL-7a and 7b were measured over a temperature range of 40°C. From the enthalpies of dissociation ΔHDiss and enthalpies of activation ΔH≠ and the strain enthalpies of 7 the bond dissociation enthalpies BDE(C—C) of 7 were determined. By comparison with the dissociation enthalpies of Ct-Ct alkanes[21] the change of these BDEs(C—C) by the cap-to-dative substitution was determined to be 85.4 kJ mol-1 (20.4 kcal mol-1). The heats of formation ΔHof (g) of a series of amino ketones 8 were determined from their heats of combustion and their heats of evaporation. From the ΔHof(g) values in combination with MM2 calculations of their strain enthalpies strain-free increments CHn[N, CO, C2 - n] with n With n = 0, 1, 2 were derived and geminal interaction enthalpies in the ground states were obtained thereof. The radical stabilization enthalpy RSE of 6 was deduced from the ΔBDE(C—C) values and the ground state effect to be 73.6 kJ mol-1 (17.6 kcal mol-1). From these data and the radical stabilization enthalpies RSE of α-aminoalkyl radicals (4.2 kJ mol-1) and α-carbonyl radicals (28.9 kJ mol-1) a synergetic radical stabilization enthalpy of 40.5 kJ mol-1 (9.7 kcal mol-1) is deduced. This number combines “extra” resonance stabilization and general inductive or anomeric geminal substituent interaction in the radicals. The crystal structure of meso-7a has been determined by X-ray diffraction methods.
    Additional Material: 2 Ill.
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  • 60
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 739-742 
    ISSN: 0009-2940
    Keywords: C—H Activation ; Palladium catalysis ; Domino coupling processes ; Palladium(IV) intermediates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By palladium catalysis substituted ortho-iodoanisoles (5, 8, 10, 13) are transformed either to annulated pyran (6) or furan derivatives (7, 9, 11, 14, 15), depending on the reactivity of additional substituents. The regiochemistry of the domino coupling processes is analyzed and a mechanistic rationale developed. Key step is the C—H activation at methoxy groups.
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  • 61
    ISSN: 0009-2940
    Keywords: Fullerenes ; Azirines ; Photochemistry ; [3 + 2] Cycloadditions ; Electron transfer reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photoreactions with C60-Fullerene. [3 + 2] Photocycloaddition of 2,3-Diphenyl-2H-azirineUpon irradiation 2,3-Diphenyl-2H-azirine (2) is added to C60 1 with formation of mono and oligo adducts. 1,9-(3,4-Dihydro-2,5-diphenyl-2H-pyrrolo)fulleren-60 (3) has been isolated and identified by standard spectroscopic methods. Mechanistic studies revealed two reaction paths leading to 3, i.e. the classic 1,3-dipolar cycloaddition via the nitrile ylide 4 (direct irradiation) or a route via 2-azaallenyl radical cations 5 (sensitization by photoinduced electron transfer).
    Additional Material: 1 Tab.
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  • 62
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 805-811 
    ISSN: 0009-2940
    Keywords: Bent metallocene complexes ; Heterodimetallic zirconium-aluminium compounds ; Hydrocarbyl-bridging ligands ; “π-Agostic” interaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The (s-trans/s-cis-η4-butadiene)zirconocene reagent adds dimethylaluminium chloride to yield the heterodimetallacyclic main group/transition-metal system 2b, containing a seven-membered metallacyclic framework that exhibits a “π-agostic” s̰-allyl zirconium interaction. Similar compounds (2c-f, 5a, 6) are obtained upon reaction of (butadiene)zirconocene with Et2All and (butadiene)hafnocene with Me2AlCl or Et2AlI. Addition of Me2AlCl or Et2AlI to (isoprene)zirconocene proceeds regioselectively to yield the corresponding heterodimetallacycles bearing the methyl substituent at C-3 (i.e. near to the attached aluminium center). The iodide-bridged heterodimetallacycles exhibit dynamic NMR spectra that indicate a rapid enantiomerization process on the NMR time scale (ΔG±ent ≈ 11-12 kcal mol-1). It is assumed that this automerization reaction proceeds by rate-limiting aluminium-halogen bond cleavage leading to an acyclic mixed metal heterodimetallic intermediate. This process is markedly inhibited by the presence of excess diethylaluminium iodide.
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  • 63
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 829-833 
    ISSN: 0009-2940
    Keywords: N-Isocyandialkylamine complexes ; Cyanamide complexes ; Guanidine complexes ; Reactions at the coordinated ligand ; N—N bond breakage ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Complexes of Functional Isocyanides, XXIV.  -  Reactions of N-Isocyanodialkylamine Complexes with Secondary AminesReactions of pentacarbonyl(N-isocyanodialkylamine) group 6-metal complexes [M(CO)5CNNR2] [M = Cr, W; R = Et, iPr; 2R = -{MeCH(CH2)3CHMe}-] with secondary amines proceed with cleavage of the N—N bond and C→N migration of the metal to give the corresponding N-cyanamide complexes [M(CO)5NCNR′2] (1a-2g) [R′ = Me, Et, nPr, nBu; 2R′ = —(CH2)4—, —(CH2)5—, —(CH2)2O(CH2)2—]. However, when diiodobis(N-isocyanodialkylamine)platinum(II) was allowed to react with an excess of the amine amine(guanidine)platinum(II) complexes [PtI2(HNR′2){HN=C(NR′2)2}] (3a-c) [R′ = Et; 2R′ = —(CH2)5—, —(CH2)2O(CH2)2—] were obtained. Structural assignments are made on the basis of IR, NMR (1H, 13C), and mass spectroscopy as well as of an X-ray structure analysis of trans-[PtI2(HNEt2){HN=C(NEt2)2}] (3a).
    Additional Material: 1 Ill.
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  • 64
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 849-851 
    ISSN: 0009-2940
    Keywords: Selenium iodides ; Imidazoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Imidazole Derivatives, IX.  -  Stabilisation of Selenium Diiodide by ComplexationHerrn Professor Helmut Werner zum 60. Geburtstag gewidmet.Stable selenium diiodide complexes 2 are obtained by the reaction of the 2-selenoxoimidazolines 1 with iodine. An X-ray structure analysis of 2c reveals its monomeric nature. In the trigonal bipyramid, the iodo substituents are situated in axial positions forming elongated iodine bonds [Se-I(1) 2.854(1), Se—I(2) 2.768(1) Å; I(1)—Se—I(2) 175.4(0)°].
    Additional Material: 1 Ill.
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  • 65
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 881-885 
    ISSN: 0009-2940
    Keywords: Fiscellanes, doubly-bridged ; Semibullvalenes, doubly-bridged ; Cyclopropanes ; SEM-protective groups ; Annulenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Reactions of the First Doubly-Bridged FiscellanesThe synthesis of the novel hexacycle 2 containing a fiscellane framework is described. Starting from Weiss' tetraester 6, the fiscellane 2 is build up in six steps by successive chemical transformation of the methoxycarbonyl functions using SEM protecting groups. The behaviour of the novel diol 2 towards introduction of several leaving groups is examined. Upon treatment with methanesulfonyl chloride the highly strained hexacycle 2 undergoes a skeletal rearrangement with formation of the triene 4. Instead of reacting to a doubly-bridged semibullvalene 3, the diol 2 gives rise to a new heterocyclic π perimeter 5 when the trifluoroacetyl derivative 12 is treated with sodium iodide in acetone.
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  • 66
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 905-909 
    ISSN: 0009-2940
    Keywords: Allyltributylstannane ; Trimethylsilyl cyanide ; α,β-Epoxy aldehydes ; Chelation-controlled addition ; Diastereoselectivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chelate-Controlled Diastereoselective Addition to α,β-Epoxy AldehydesLiClO4-mediated reaction of trans-substituted α,β-epoxy aldehydes 1 with allyltributyltin (2) or trimethylsilyl cyanide provides a general method for the synthesis of the corresponding syn-alcohols 3 with high selectivity. In the case of cis-substituted α,β-epoxy aldehydes the selectivity depends on the size of the substituents.
    Additional Material: 2 Tab.
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  • 67
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 947-953 
    ISSN: 0009-2940
    Keywords: 1-Aza-2-azoniaallene cations ; Isocyanates ; 4,5-Dihydro-5-oxo-1,2,4-triazolium salts ; Cinnolinium salts ; Cycloadditions ; Calculations, AM1 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Aza-2-azoniaallene salts 3, prepared in situ from geminal chloroalkylazo compounds 2 with Lewis acids, react with isocyanates 4 to give 4,5-dihydro-5-oxo-3H-1,2,4-triazolium salts 6 and 4,5-dihydro-5-oxo-1H-1,2,4-triazolium salts 7, respectively. The intramolecular cyclization of 3u opens a new route to cinnolinium salts 11. Allenes 3 react with isobutene to give pyrazolium salts 8. According to AM1 calculations the cycloadditions of 3 to isocyanates proceed in two steps via acylium salts 5 as intermediates. Mechanistically, the rearrangements 6 → 7 resemble Wagner-Meerwein rearrangements rather than pericyclic [1,5]-sigmatropic shifts.
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  • 68
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 965-966 
    ISSN: 0009-2940
    Keywords: Cyclophanes ; Photochemistry ; Triplet states ; Enolization ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: When ethanolic solutions of 4-(1-naphthoyl)[2.2]paracyclophane (3) and 4-(2-naphthoyl)[2.2]paracyclophane (4) are subjected to UV irradiation at low temperature, 1,5-hydrogen migration of the 2-H bridge proton to the carbonyl group takes place, leading to the enol of type 2. In the context of mechanistic considerations the triplet spectroscopic properties of 3 and 4 are discussed.
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  • 69
    ISSN: 0009-2940
    Keywords: Cyclophosphahydrazides ; Dinitrogen-bridged ; Conformation ; Chair and Boat forms ; Dinuclear Mo(0) complexes ; 1,2,4,5,3,6-Tetrazadiphosphorinanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of methylhydrazine with RPC12 (R = Et, tBu, and Ph) produced the cyclic phosphorus (III) hydrazides (1,2,4,5,3,6-tetrazadiphosphorinanes) [RPN(Me)N(H)2 (R = Et, 1; (Ph, 2; tBu, 3) in good yields. The 1H-and 31P-NMR spectroscopic analysis indicated that 1 exists in chair and boat conformations. However, it crystallizes in the chair conformation exclusively. The X-ray crystallographic investigation of all the three cyclo-phosphorus hydrazides 1-3 confirms the existence of these compounds in the chair conformations in the solid state. The reaction of Mo(CO)4-(NHC5H10)2 with 1 and 2 gives the dinuclear Mo(0) complexes [{Mo(CO)4(NHC5H10)}2(μ-[RPN(Me)N(H)]2}] (R = Et, 5; Ph, 6). Based on 1H- and 31P-NMR spectroscopic data, a bridging dinuclear dimetallic formulation is proposed for 5 and 6. The IR spectra indicate that the carbonyls are disposed in cis-geometry around the Mo(0) center.
    Additional Material: 6 Ill.
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  • 70
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2373-2379 
    ISSN: 0009-2940
    Keywords: Chelating ligands ; Molybdenum complexes ; Peroxo complexes ; Catalysis ; Olefine epoxidation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituted N,N-Chelate Ligands - Applications in Molybdenum-Catalyzed Epoxidation of Olefins*Oxodiperoxomolybdenum complexes 4 of substituted 2-[3(5)-pyrazolyl]pyridines (2a-g) were synthesized in order to control the solubility of these complexes in organic solvents. Alkyl side chains (butyl, octyl, octadecyl) increase the solubility of the complexes and enable spectroscopic investigations in solution. Due to the symmetry of the ligands the peroxo complexes 4 appear in two isomeric forms, with the terminal oxo ligand in the trans position either to pyridine or to pyrazole. The latter isomer of (C5H4NC3H2N2CH2COOEt)MoO(O2)2 (4f) was characterized by an X-ray structure analysis. The alkyl-substituted peroxo complexes are active catalysts for the epoxidation of olefins with tert-butyl hydroperoxide.
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  • 71
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2397-2401 
    ISSN: 0009-2940
    Keywords: [Amino(imino)phosphane]gallium trichloride adduct ; 1,3-Diaza-2λ2-phosphonia-4λ4-gallatacyclobutanes ; Nickel tricarbonyl complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Diaza-2λ2-phosphonia-4λ4-gallatacyclobutanesReaction of amino(imino)phosphanes 1a-c with gallium trichloride results in the formation of 1,3-diaza-2λ2-phosphonia-4λ4-gallatacyclobutanes 3a, b with elimination of chlorotrimethylsilane (1a) or tert-butyl chloride (1b, c). The intermediately formed amino(imino)phosphane/Lewis acid adducts R(Me3Si)NPN(GaCl3)R′ (2, R,R′ = tBu, Me3Si) can be isolated in the case of compound 2a (R = R′ = SiMe3). A diazaphosphasilacyclobutane - gallium trichloride adduct 4 is formed in a side reaction by isomerization of 2a. Reaction of compound 3b with Ni(CO)4 gives the corresponding transition metal complex 5. The NMR data and X-ray structures of compounds 2a, 4, and 5 are reported.
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  • 72
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2393-2396 
    ISSN: 0009-2940
    Keywords: 1,4-Diborafulvenes, 1,4-dihydro- ; Slipped triple-decker ; Nickel complexes ; platinum complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexation of 1,4-Dihydro-1,4-diborafulvenes with Ni(cod) and Pt(cod) Fragments*Reactions of the 1,4-diborapentafulvene derivatives 1 and 2a, b with M(cod)2 (M = Ni, Pt) yield the complexes [(η5-1)Ni-(cod)] (8), [(μ,η2η5-2a){Ni(cod)}2] (9a), [(μ,η2,η5-2b){Ni(cod)}2] (9b), and [(μ,η2,η5-2a){Pt(cod)}2] (10). Compounds 9 and 10 are the first examples of complexes with 2a, b as a μ,η2,η5-ligand. The X-ray structure analyses of 9b and 10 are described.
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  • 73
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2511-2518 
    ISSN: 0009-2940
    Keywords: Allylboration, stereoselective ; Erythronolide building blocks ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chiral pentenylboronate 3 was the key reagent in the stereoselective construction of two erythronolide building blocks 6 and 7. Addition of 3 to achiral aldehydes furnished homoallylic alcohols 21 and 26 with 〉98% e.e. Addition of 3 to chiral aldehydes 8 or 11 generated homoallylic alcohols with 〉95% d.e. In the mismatched case of addition to the aldehyde 29 diastereoselectivity reached merely 80%.
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  • 74
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2535-2537 
    ISSN: 0009-2940
    Keywords: Cobalt complexes, (η3-allyl)(η5-pentamethylcyclopentadienyl)- ; Pyridine synthesis ; Catalytic activity ; Chemoselectivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (η3-Allyl)(η5-pentamethylcyclopentadienyl)cobalt - a Selective Catalyst for the Pyridine Synthesis(η3-Allyl)(η5-pentamethylcyclopentadienyl)cobalt (1) catalyses the synthesis of various pyridines from alkynes and nitriles under mild conditions. Only small amounts of benzenes are formed in this selective reaction.
    Additional Material: 1 Ill.
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  • 75
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1317-1322 
    ISSN: 0009-2940
    Keywords: Cyclization of a hydroxy triketone ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A protected hydroxy triketone 22 has been generated by direct Swern oxidation of a δ-trimethylsilyloxy alcohol 11, avoiding the formation of a δ-hydroxy ketone as an intermediate. Conditions have been worked out, which allow the deprotection of a tert-butyldimethylsilyl group and the spontaneous tricyclization of the resulting hydroxy triketone 4 to an acid-sensitive hydroxytrioxaadamantane 5.
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  • 76
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1327-1329 
    ISSN: 0009-2940
    Keywords: Macrocyclic thioethers ; Adamantane as a building block ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 4,6:12,14-Di(1,3-adamantano)-1,9-dithiacyclohexadecane (1), 4,6:12,14:20,22-tri(1,3-adamantano)-1,9,17-trithiacyclotetracosane (2), and 5,7:14,16-di(1,3-adamantano)-1,2,10,11-tetrathiacyclooctadecane (3) have been obtained by intermolecular cyclization of 1,3-bis(2-bromoethyl)adamantane (4) with thioacetamide using a high-dilution technique. The reaction is concentration-dependent. The crystal structures of 1, 2, and 3 have been determined by single-crystal X-ray diffraction.
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  • 77
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    Berichte der deutschen chemischen Gesellschaft 127 (1994) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 78
    ISSN: 0009-2940
    Keywords: Dipyrrolo[1,2a:1′,2′-d]pyrazine, (5aS,10aS)-octahydro-1H,5H- ; 1,2-Addition, enantioselective ; Grignard reagents ; Chiral solvent ; Cryoscopic measurements ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (5aS,10aS)-Octahydro-1H,5H-dipyrrolo[1,2-a:1′,2′-d]pyrazine «DPP» as Auxiliary Reagent for Enantioselective Alkylations of Prochiral Carbonyl CompoundsIn the presence of one equivalent of the title compound «DPP» (1) prochiral carbonyl compounds 2 react with Grignard reagents 3 in THF to form enantioselectively alcohols 4 with up to 98% ee, whereas the addition of one equivalent of triethylamine yields the opposite enantiomers with up to 97% ee. The optimal molar ratio of 1 and magnesium reagent 3 was determined by cryoscopic measurements. Asymmetric induction is supposed to arise from transition states involving monomeric octahedral complexes of Grignard reagent, chiral solvent, and carbonyl compound. DPP (1) also catalyses Grignard alkylations, because a tenth of its stochiometric amount gives an enantiomeric eccess four times more than as expected. Prepared from (S)-proline, only the boat conformation of 1 induces the observed selectivity as detected by 13C-NMR spectroscopy.
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  • 79
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1331-1332 
    ISSN: 0009-2940
    Keywords: Primary enamines ; Borylation ; 9-BBN ; Amino-polyene ; Enamines, borylation of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stable conjugated primary enamine 1,6-diamino-1,6-diphenyl-1,3,5-hexatriene (2a) was treated with 9-borabicyclo-[3.3.1]nonane. At 40°C in dichloromethane solution (18 h) only borylation at nitrogen was observed. With loss of dihydrogen a 9-BBN substituent became attached to each enamine nitrogen. The N,N′-diborylated diaminohexatriene product 3 was characterized by X-ray diffraction.
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  • 80
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1349-1353 
    ISSN: 0009-2940
    Keywords: Isophosphaalkynes ; Transition metal complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition-Metal-Substituted Acylphosphanes and Phosphaalkenes, XXI.  -  Isophosphaalkynes as μ3-Ligands in Transition Metal ComplexesReaction of the μ-isophosphaalkyne complex (η5-C5H5)2 (CO)2(μ-CO)Fe2(μ-CPMes) (Mes = 2,4,6-Me3C6H2) (2a) with [(Z)-Cyclooctene]Cr(CO)5 or Fe2(CO)9 gives rise to the μ3-isophosphaalkyne complexes (η5-C5H5)2(CO)2(μ-CO)Fe2{μ-CP[M(CO)n]Mes} 3a [M(CO)n = Cr(CO)5] and 4a [M(CO)n = Fe(CO)4]. Similarly (η5-C5H5)2(CO)2(μ-CO)Fe2{μ-CP[Cr (CO)5]C6H2(CF3)3-2,4,6} (3d) is obtained. The metal carbonyl fragments are attached to 2 in a η1-fashion by the lone-pair at the phosphorus. In contrast to this the treatment of 2a with (Ph3P)2Pt(η2-C2H4) affords complex 5a in which 2a serves as an η3-3e ligand towards the PtPPh3 moiety. The molecular structures of 3a and 5a are determined by single-crystal X-ray analysis.
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  • 81
    ISSN: 0009-2940
    Keywords: Ruthenium compounds ; Osmium compounds ; Alkynes, activated ; Cyclotrimerization ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Depending on the substituents, the reaction of the activated alkynes ZC≡CZ (2a-g) [Z = CO2R: R = Me (a), Et (b); Z = R1: R1 = CF3 (c), CH2Cl (d), CH2Br (e); Z = CH2OC(O)R2: R2 = Me (f), CCl3 (g)] with the labile ruthenium complex (η2-C2H4)Ru(CO)4 (1) results in the formation of three different types of heterocycles. While the reactions of the dialkyl acet-ylenedicarboxylates 2a, b lead to the dimeric tricarbonylru-thenacyclopentadienes 3a, b, being catalytically active in the cyclotrimerization of alkynes like 2a, b, the application of the 1,4-halogeno-2-butynes 2c-e yields the bicyclic heterocycles 4c-e. The esters of 2-butyne-1,4-diol 2f, g are converted into the tetracarbonylruthenacyclopentadienes 5f, g. Investigation of the primary attack of the alkynes 2a-g at complex 1 leads to the conclusion, that an ionic mechanism is preferred in the ruthenium-catalyzed cyclotrimerization of electron-poor alkynes. If, instead of 1, (η2-C2H4)Os(CO)4 (6) is allowed to react with the acetylenes 2a, b the osmium complexes (η4-C6Z6)Os(CO)3 (7a, b) are isolated. In the presence of CO at 2 bar 7a, b release the benzene derivatives C6Z6 (8a, b) with the formation of Os3(CO)12.
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  • 82
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1335-1342 
    ISSN: 0009-2940
    Keywords: Fulvalenes ; Bismuth complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bismuth Compounds with Crowded Multiply Alkylated Cyclopentadienyl LigandsHerrn Professor Helmut Werner zum 60. Geburtstag gewidmet.Bismuth complexes of alkylated cyclopentadienyl ligands are obtained in good yield on treating bismuth(III) halides with tetraisopropylcyclopentadienylsodium or 1,2,4-tri-tert-butyl-cyclopentadienyllithium. A 1:1 stoichiometric ratio gives the complexes [Cp4iBiCl2] (1), [Cp3tBiCl2] (2), and [Cp4iBiI2] (3) (Cp4i = C5iPr4H, Cp3t = C5H2tBu3-1,2,4). According to X-ray crystal structure analyses, 1 and 3 display dimeric structures with two bridging and two terminal halogeno ligands and η3-coordination of the cyclopentadienyl rings. With half an equivalent of tetraisopropylcyclopentadienylsodium BiCl3 forms [Cp4iBi2Cl5] (4). An X-ray crystal structure analysis of 3 reveals a central Bi2Cl10 core of two edge-sharing BiCl6 octahedra coordinated to two Bi(η5-Cp4i) fragments generating a framework of two face-sharing cubes. Reaction of two equivalents of 1,2,4-tri-tert-butylcyclopentadienyllithium with BiCl3 yields deep purple [Cp3t2BiCl] (5), a bent sandwich complex with an η3,η2-bonding mode of the cyclopentadienyl ligands. Attempted formation of the octaisopropyl analogue of 5 from BiCl3 and two equivalents of tetraisopropylcyclo-pentadienylsodium with elimination of propene gives [Cp4iCp3iBiCl] (6) (Cp3i = C5H2iPr3). Use of monodeuterated tetraisopropylcyclopentadienylsodium in the second substitution step gave pure [Cp4i([D1]Cp3i)BiCl] ([D1]6) proving the absence of ring exchange reactions under the reaction conditions employed and elimination of propene from the second incoming sterically crowded tetraisopropylcyclopentadienyl ring system. The importance of proper choice of solvent and reaction conditions on the formation of alkylated cyclopentadienyl bismuth derivatives is demonstrated by extensive formation of 1,1′,3,3′,5,5′-hexa-tert-butyldihydrofulvalene (7) from 1,2,4-tri-tert-butylcyclopentadienylsodium and BiCl3.
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  • 83
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1355-1357 
    ISSN: 0009-2940
    Keywords: Diphosphanylhydrazides ; Diphosphanes, dinitrogen-bridged ; Cycloplatinaphosphahydrazides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: While the transition metal complexes of bis(phosphanyl)amines (PII-N-PIII) have been known for over three decades, the ligating properties of the next homologue PIII-N-N-PIII have been unprecedented so far. The X-ray structures of cycloplatinaphosphanehydrazides, [(OR)2PN(Me)N(Me)P(OR)2-PtCl2], reveal short distances for the P-N [1.639(5) Å] bonds.
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  • 84
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1359-1362 
    ISSN: 0009-2940
    Keywords: Silanes ; Siloxanes ; Si - C bond, selective cleavage ; Arylsilylmethanes ; Si,C,O single-source CVD precursor ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A synthetic route to partly silylated tetra(silyl)methanes (ArH2Si)nC(SiH3)4  -  n′ to their precursors (TfH2Si)nC-(SiH2Ar)4  -  n (Ar = p-tolyl, phenyl; Tf = CF3SO3; n = 3, 2, 1), and to 1,3-bis(trisilylmethyl)disiloxane [(H3Si)3CSiH2]2O (9) is reported. Starting from symmetrical tetrakis(arylsilyl)-methanes (aryl = p-tolyl, phenyl), we have obtained the selectively dearylated (arylsilyl)silylmethanes (ArH2Si)nC(SiH3)4  -  n (Ar = p-tolyl, phenyl; n = 3, 2, 1) by Si - Ar cleavage with equivalent quantities of trifluoromethanesulfonic acid (triflic acid) and hydrogenation of the corresponding silyl triflates (TfH2Si)nC(SiH2Ar)4  -  n (n = 3, 2, 1) with LiAlH4. The synthesis of 9 has been accomplished by treating trisilyl(p-tolylsilyl)methane p-TolH2SiC(SiH3)3 (7) with stoichiometric amounts of triflic acid to give (trisilylmethyl)silyl triflate TfH2SiC(SiH3)3 (8) and hydrolysing the latter with water.
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  • 85
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1363-1368 
    ISSN: 0009-2940
    Keywords: 1,2-Diboroles, 2,5-dihydro- ; 1,3-Diboroles, 2,3-dihydro- ; Cobalt complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A New Approach to 1,2- and 1,3-DiboroleHerrn Prof. Dr. Joachim Knappe zum 65. Geburtstag gewidmet.Diaminoborylation of 1,3-dilithiopropenes leads to the (Z)-1,3-bis(diaminoboryl)propenes 4a, b, which are transformed by an amine/chlorine exchange to the (Z)-1,3-bis(aminochloroboryl)propenes 5a, b. These react with sodium to yield the 2,5-dihydro-1H-1,2-diboroles 2c, d, whereas the reaction with potassium leads to the 2,3-dihydro-1H-1,3-diboroles 6a, b by rearrangement of the C3B2 skeleton. The constitutions of the heterocycles 2c, d and 6a, b are established by X-ray structure analyses. Reaction of the 1,2-diboroles 2c, d with (C5H5)Co(C2H4)2 leads to the red (1-borabutadiene)cobalt complexes 3c, d. In 3c a sigmatropic rearrangement is studied by NMR spectroscopy.
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  • 86
    ISSN: 0009-2940
    Keywords: Tungsten complexes ; Rhenium complexes ; Iron complexes ; Ruthenium complexes ; Osmium complexes ; Cobalt complexes ; Vinyl ; Cyclohexadienyl ; Cycloheptadienyl ; Cyclooctatrienyl ; Hydrocarbon-bridged complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrocarbon-Bridged Complexes, XXX.  -  Nucleophilic Addition of Carbonylmetallates to Cationic Vinyl, Diene, Dienyl and Triene Complexes of Iron, Ruthenium and Cobalt: Di-, Tri-, Tetra- and Pentametallic Complexes with σ,σ- and σ,π-Hydrocarbon BridgesHerrn Professor Ekkehard Lindner zum 60. Geburtstag gewidmet.The reactions of [Re(CO)5]-, [Ru(CO)2Cp]-, and [Os(CO)4]2- with [Cp2(OC)2Fe2(μ-CO)(μ-η1:η2-CH=CH2)]+, [Cp*Ru(η2:η4-1,3,7-octatriene)]+, [(OC)Fe(η4-diene)(η5-cycloheptadienyl)]+, and [CpCo(η5-cyclodienyl)]+ give the nucleophilic adducts whereas with [Mn(CO)5]-, [W(CO)3Cp]-, and [Fe(CO)2Cp]- formation of the corresponding C-C coupling products and of the metal-metal-bonded dimers is observed. The structures of Cp*Ru(μ-η1:η2:η3-1,5-octadienyl)Re(CO)5 (4), [Cp* Ru(μ-η1:η2:η3-1,5-octadienyl)]2Os(CO)4 (6), and of (OC)-Fe(η4-1,3-cyclohexadiene) (μ-η1:η4-1,3-cycloheptadiene)Re(CO)5 (9) have been determined by X-ray diffraction.
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  • 87
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1379-1385 
    ISSN: 0009-2940
    Keywords: Hydrotris(triazolyl)borate ; metal complexes ; Chelate ligands ; Clathrates ; Magnetochemistry ; Spin crossover ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bis[hydrotris(1,2,4-triazolyl)borate]metal complexes [M{HB(C2H2N3)3}2] with M = Fe (5), Co (6), Cu (7), Zn (8) are obtained from MX2 and K[HB(C2H2N3)3] (9). The complexes are characterized by IR, UV/Vis, and MS. Temperature-variable magnetic measurements show a Curie-Weiss behavior for the paramagnetic complexes 6 and 7 with a temperature-dependent magnetic moment for 6. The iron complex 5 exhibits a spin crossover from diamagnetic to paramagnetic, starting at around 270 K. Single-crystal X-ray structures of the solvates 7 · 4 CH3OH and 9 · 2 H2O have been determined. The structure of 7 · 4 CH3OH shows the Jahn-Teller distorted copper complex 7 surrounded by methanol molecules through hydrogen bonding to exocyclic nitrogen atoms of the tris(1,2,4-triazolyl)borate ligand. The crystal system for 7 · 4 CH3OH is monoclinic, space group P21/n. Compound 9 · 2 H2O is a one-dimensional coordination polymer with the potassium atom bridged by the water molecules and the tris(1,2,4-triazolyl)borate ligand and crystallizes in the orthorhombic space group Ccm21.
    Additional Material: 5 Ill.
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  • 88
    ISSN: 0009-2940
    Keywords: 2-Azapropenylium salts, 1,3-dialkoxy- and 1,1,3,3-tetraalkoxy- ; Enamines of N-methyl-4-piperidone ; 4-Aminopyridines ; 3,7-Diazabicyclo[3.3.1]non-2-en-9-ones ; Retro-Mannich reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Dialkoxy-2-azapropenylium salts 1 react with enamines 2 of N-methyl-4-piperidone at room temperature to give 2,6-disubstituted 4-aminopyridines 4, 5 in low to moderate yield after hydrolysis. Intermediates of the reaction of 1a with 2 are the bicyclic iminium salts 6 and 7, which may be detected 1H-NMR spectroscopically prior to hydrolysis. Hydrolysis of the mixture obtained from the reaction of 1a with 2a under basic conditions furnishes the bicyclic ketone 3 as the major product. A “retro-Mannich”-type reaction is suggested to explain the degradation of the bicyclic intermediates 6, 7 with the formation of the pyridines 4, 5.
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  • 89
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    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1441-1445 
    ISSN: 0009-2940
    Keywords: Vinylstannanes ; Photooxygenation ; Schenck reaction ; Hydroxy epoxidation ; Stannyl epoxy alcohols ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The direct synthesis of stannyl epoxy alcohols 3 from vinylstannanes 1 is described. The procedure involves the photooxygenation of Vinylstannanes 1, which proceeds in a highly regioselective manner with predominant hydrogen abstraction geminal to the stannyl group. Subsequent reaction of the resulting hydroperoxides 2 with Ti(OiPr)4 afforded in a one-pot procedure the epoxy alcohols 3 in high diastereomeric excess, which ranged from 81:19 to greater than 95:5. This convenient and effective method was applied to acyclic and cyclic vinylstannanes as well as to γ-trydroxyvinylstannane 1e, which was converted into the stannyl epoxy diol 3e. In this novel hydroxy epoxidation of vinylstannanes the regioselectivity of the singlet oxygen ene reaction (Schenck reaction) is controlled by the stannyl group.
    Additional Material: 1 Tab.
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  • 90
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1447-1457 
    ISSN: 0009-2940
    Keywords: Addition Stereoselective, nonchelation-controlled ; Reagent, organozinc ; Stereodifferentiation, double ; Oligo(tetrahydrofuran) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The additions of the enantiomerically pure organozinc reagents 17 and 33 to the THF-aldehyde 1 in the presence of the monodentate Lewis acid boron trifluoride - ether give the nonchelation-controlled addition products 7 and 36, respectively (stereoselectivity 95:5, 86:14). These results provide a route to oligo(tetrahydrofuran)s with the relative stereochemistry trans-syn-cis. A stereodirecting effect of the chiral center in the organozinc reagent 17 is found, leading to simple diastereoselectivies in the reaction with achiral aldehydes and to a matched-mismatched case in the reaction with the chiral aldehyde 1.
    Additional Material: 1 Tab.
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  • 91
    ISSN: 0009-2940
    Keywords: Cyclopropenes, 3,3-dimethyl, 1-substituted ; Cyclopropenylzinc chlorides, coupling reactions of ; Palladium catalysis ; Cyclopropenylstannanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [3,3-Dimethyl-2-(trimethylsilyl)-1-cyclopropen-1-yl]zinc chloride (4) reacts with haloarenes and -alkenes as well as 1-bromo-acetylenes under Pd(0) catalysis to give the corresponding 1-phenyl-, 1-ethenyl-, and 1-ethynyl-1-cyclopropenes 6 in isolated yields ranging from 47 to 99%. The corresponding 1-cyclopropen-1-ylstannane 5 reacts with haloarenes only at higher temperatures, and the yields range from 10 to 98%, depending on the substrate and reaction conditions.
    Additional Material: 1 Tab.
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  • 92
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1747-1753 
    ISSN: 0009-2940
    Keywords: Isomerization, thermal ; Radicals ; D-Labeling ; 1,5-Hexadiyne ; Pentafulvene ; Rearrangement, homoallyl ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermal Rearrangements, XXIII[1].  -  The Thermogram of a C6H6 Chemistry in the Temperature Range from 450 to 730°CThe thermal isomerization of 1,5-hexadiyne (1) and its [1,6-D2]-labeled derivative (1a) was studied in the temperature range 450-730°C and in the presence of different carrier gases (N2, H2, D2, N2/toluene). By detailed analysis (GC, GC MS, NMR) all volatile reaction products were identified and determined quantitatively by using hexafluorobenzene as an internal standard. The experimental data show clearly that the reaction products are formed by two different routes: (i) electrocyclization leading to dimethylene cyclobutene (3) at temperatures up to about 600°C and (ii) radical reaction leading to benzene (4) and pentafulvene (5) at temperatures above 550°C. Cyclopentadienylmethyl radicals are supposed to be the essential radical intermediates.
    Additional Material: 2 Ill.
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  • 93
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1765-1779 
    ISSN: 0009-2940
    Keywords: Diradicals ; NO and O2 trapping ; Heat of formation ; Energy well ; Rearrangments ; Bergman cyclisation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Energy Well of Diradicals, V[1].  -  1,3,5-Cyclohexatriene-1,4-diyl and 2,4-Cyclohexadiene-1,4-diylThe energy profile of the Bergman rearrangement of (Z)-3-hexene-1,5-diyne (4) has been established from the NO and oxygen dependance of the trapping rate of the intermediate diradical 1 which leads to a heat of formation for 1,4-didehy-drobenzene (1) of δHOf= 138.0 ± 1.0 kcal . morl-1. By the same technique the heat of formation of 1,2,4-cyclohexatriene (2), generated by thermolysis of (Z)-1,3-hexadien-5-yne (10), gives δHOf = 105.1 ± 1.0 kcal . mol-1 which indicates a high diradical character for 2.
    Additional Material: 4 Ill.
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  • 94
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1797-1798 
    ISSN: 0009-2940
    Keywords: Titanocenes ; Fulvenes ; Solvent effect ; Ketyls ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Reaction of Bis(trimethylphosphane)titanocene with KetonesFulvenes are the products of the reaction of aliphatic and aromatic ketones with bis(trimethylphosphane)titanocene in nonpolar solvents, but no formation of pinacols is observed. The mechanism is discussed.
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  • 95
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1781-1795 
    ISSN: 0009-2940
    Keywords: Resonance energy ; Stabilisation energy ; Propargyl resonance ; Force field calculation ; Intrinsic rotational barrier ; Single pulse shock tube ; Gasphase kinetics ; Heats of hydrogenation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Propargyl Stabilisation EnergyFor the alkynyl-substituted olefines 1-14 activation parameters for the geometrical isomerisation have been determined in the gasphase by the single-pulse shoke-tube technique. By comparison of these barriers with the corresponding one of the isolated double bonds, each corrected by the steric energy contribution of the ground and transition state, a value of 7.8 ± 1.3 kcal · mol-1 for the propargyl stabilisation energy (PrSE) has been derived.
    Additional Material: 11 Tab.
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  • 96
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1799-1802 
    ISSN: 0009-2940
    Keywords: as-Triazinium salt, fused ; Ring opening ; Ring transformation Heteroaromaticity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ring transformation of the tricyclic furo-fused as-triazinium salt 1 in the presence of nucleophilic reagents (e.g. sodium hydrogensulfide, sodium salts of malonic ester, ethyl cyanoacetate, acetylacetone, dimedone, or malononitrile) leads to the two new heteroaromatic ring systems thieno[2,3-e]pyrido[1,2-b]-as-triazinium salt (5) and differently substituted cyclopenta[e]pyrido[1,2-b]-as-triazine compounds (8, 9, 10, 11, and 13).
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  • 97
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1803-1806 
    ISSN: 0009-2940
    Keywords: Singlet carbenes ; [4 + 1] Cycloadditions ; 1,2,4,5-Tetrazines ; SEAr reactions, intramolecular ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Wanzlick Carbenes in the [4 + 1] Cycloaddition Reaction with Bis(methylthio)- and Bis(trifluoromethyl)-1,2,4,5-tetrazineThe 3,6-disubstituted 1,2,4,5-tetrazines 3 and 4 have been submitted to a [4 + 1] cycloaddition reaction with the nucleophilic singlet carbenes (Wanzlick carbenes) 2a-d, which are generated from the precursors 1a-d. With 3 as diazadiene the expected spiro compounds 6a-d are formed. In contrast to this presumed two-step reaction sequence of 3, with the tetrazine 4 the cascade cycloaddition/cycloelimination is surprisingly followed by an intramolecular electrophilic aromatic substitution to yield the chiral tetracyclic compounds of type 8 with high diastereoselectivity. The crystal structure of 8d has been determined by X-ray diffraction methods.
    Additional Material: 1 Ill.
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  • 98
    ISSN: 0009-2940
    Keywords: Stannanes, α-(alkylthio) ; Wittig rearrangement ; Configurational stability ; α-Lithio sulfides ; [2,3] Rearrangement ; Stereoselectivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The nBuLi-induced tin/lithium exchange reactions of the di-astereomeric γ-[(methoxyethoxy)methoxy]-]α-(tributylstannyl) sulfides anti- and syn-8 delivered the α-(lithioalkyl) benzyl sulfides anti- and syn-11, respectively. Within 1 h at -78°C, these species underwent [2,3]-thia-Wittig rearrangements in THF via the de-aromatized cyclohexadiene intermediates syn- and anti-12. Tautomerization and protonation yielded 81:19 (85%) and 19:81 mixtures (96%) of the ortho-functionalized toluenes syn- and anti-13. Probably, both Wittig rearrangements proceeded with 100% inversion of configuration at the carbanionic stereocenter, and the overall loss of stereoselectivity is due to an epimerization anti-11 ⇌ syn-11 of the lithio sulfide intermediates at a rate which is 3.3 times slower than the rearrangement.
    Additional Material: 2 Tab.
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  • 99
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1959-1968 
    ISSN: 0009-2940
    Keywords: Aldol reaction ; Chiral etiolate ; Mandelic acid ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The propionates (R)-5 and (R)-6 which are derived from the readily available chiral auxiliary reagent (R)-triphenylglycol (4) have been applied in stereoselective aldol reactions. Whereas the enolate 7 and the silyl ketene acetal 12, both generated from the ester (R)-6, display only moderate diastereoselectivity when treated with benzaldehyde, ß-hydroxyesters 8b and 16a, b are formed in diastereomeric ratios up to 95:5 (ratio of the main product to the sum of all other stereoisomers) when the propionate (R)-5 is subsequently deprotonated, transmetalated into the zirconium enolate and allowed to react with aldehydes. Alkaline hydrolysis or reduction with LiAlH4 enables the conversion of the adducts 8a and 16a
    Additional Material: 3 Ill.
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  • 100
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1933-1947 
    ISSN: 0009-2940
    Keywords: 7-Oxonorbornane-2,3-dicarboximides ; Reductive amination ; 4,7-Methanoisoindoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ozonizations of several 7-isopropylidenenorbornane-2,3-dicarboximides (2, 10) yield 7,7-dihydroxynorbornane-2,3-dicarboximides (3, 11) and/or 7-oxonorbornane-2,3-dicarboxi-mides (4, 12). Dehydration of the dihydroxy derivatives to the corresponding carbonyl compounds can be carried out by reaction with P2O5 in an aprotic solvent. Reaction of hydrates 3 with methanol gives mixtures of the stereoisomeric hemiacetals 13 and 14, whereas reaction with other nucleophiles give only the stereoisomer derived from attack by the less hindered carbonyl face. Thus NaBH4 or Al(iPRO)3 reduction of 3 or 4 yields alcohols 15 and LiAlH4 reduction of 3 or 4 amino alcohols 16. Reaction of 4b with phenylmagnesium bromide gives alcohol 22 and a direaction product (rac-26) that easily dehydrates to a tetracyclic compound (rac-30). Reductive aminations of 3 or 4 lead to amines 19 directly or via imines rac-20 and amines 23. LiAIH4 reduction of amine 23b affords tricyclic compounds (rac-27) and (rac-28). The last one was converted to diamine 24 by reduction with NaBH3CN. Similarly, amine 21 was converted into diamine 25, partially via aminal 29 as intermediate. The structures of compounds 3b, 19a, rac-27, and rac-30 have been established by X-ray diffraction analysis.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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