Alkyldiphenylphosphine oxides typically undergo α‐deprotonation with alkyllithium reagents. Here, the lithiation of differentially branched alkyldiphenylphosphine oxides was investigated and a diverse, but predictable reactivity was found. γ‐Branched derivatives undergo selective directed ortho‐metalation (DoM) using butyllithium and TMEDA as an additive. With decreasing degree of γ‐branching α‐lithiation becomes predominant. The ortho‐phosphinoyllithium intermediates are subject to functionalization and C C bond forming reactions, thus providing a convenient approach to new phosphine oxides and phosphine‐borane complexes, which have a good potential for an approach to new ligands for catalysis.
A field-programmable, stackable memory cell using 0.15-/spl mu/m technology is demonstrated. Vertical polycrystalline silicon diodes are stacked on top of one another, with tungsten (with TiN adhesion film) interconnect wires. An SiO/sub 2/ antifuse film separates the top of each diode from the TiN-W films. The cell is programmed when sufficient biasing voltage is applied to break down the antifuse, connecting the diode to tungsten. The cell is unprogrammed when the antifuse is intact. Cell fabrication and performance are described. 相似文献
A hybrid simulation tool for real-time performance measurements of complete networks is presented. The simulation tool combines the advantages of software and hardware modules. Recorded channel data are included. They allow the reproduction of realistic situations in the laboratory. Synchronization problems and noise are considered. As an example, stabilized slotted ALOHA access protocols were implemented and investigated in land-mobile satellite environments. A slotted ALOHA-based modified channel access strategy for highly unreliable channels is proposed requiring all mobile stations to estimate the link quality before starting a transmission. The different strategies are analyzed by simulation as well as the analytical methods. Transmission parameters are determined and optimized using a combination of analysis and simulation. The results show the power of the simulation tool and the better performance of stabilized slotted ALOHA with link-quality estimation in city channels 相似文献
Early zoological researches by P.S. Pallas and K.E. von Baer in their letters to the zoologists of Berlin. The centenaries which are celebrated in 1991 and 1992 in memory of P.S. Pallas (1791) and K.E. von Baer (born 1792) caused the following studies of hitherto unpublished sources, preserved in the collections of the Museum für naturkunde in Berlin. The earliest zoological works of Pallas are discussed in relation to his last publication on the “Zoographia Rosso-Asiatica” which should have been finished in Berlin. Some years after the death of Pallas, Baer also contacted the Berlin zoologists K.A. Rudolphi and M.H. Lichtenstein, asking for help, when he was going to establish zoology and a zoological museum at the University of Königsberg. 相似文献
We report a case of birdshot retinochoroidopathy following a cataract surgery in a 78-year-old man. Low-grade forms of the affection may be discovered lately on a recurrence of the inflammation following any event as an ocular surgical procedure. Medical management of cataract surgery in uveitis is then discussed. 相似文献
In this paper, we report a methodology, developed in the context of Smart Energy Efficient Middleware for Public Spaces European Project, aimed at exploiting ICT monitoring and control services to reduce energy usage and CO2 footprint in existing buildings. The approach does not require significant construction work as it is based on commercial-off-the-shelf devices and, where present, it exploits and integrates existing building management systems with new sensors and actuator networks. To make this possible, the proposed approach leverages upon the following main contributions: (a) to develop an integrated building automation and control system, (b) to implement a middleware for the energy-efficient buildings domain, (c) to provide a multi-dimensional building information modelling-based visualisation, and (d) to raise people’s awareness about energy efficiency. The research approach adopted in the project started with the selection, as case studies, of representative test and reference rooms in modern and historical buildings chosen for having different requirements and constraints in term of sensing and control technologies. Then, according to the features of the selected rooms, the strategies to reduce the energy consumptions were defined, taking into account the potential savings related to lighting, heating, ventilation, and air conditioning (HVAC) systems and other device loads (PC, printers, etc.). The strategies include both the control of building services and devices and the monitoring of environmental conditions and energy consumption. In the paper, the energy savings estimated through simulation, for both HVAC and lighting, are presented to highlight the potential of the designed system. After the implementation of the system in the demonstrator, results will be compared with the monitored data. 相似文献