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61.
A 5.8 GHz Low Noise Amplifier for Wireless LAN Applications in Silicon Bipolar Technology 总被引:1,自引:0,他引:1
Gerd Schuppener Mehran Mokhtari Boris Kerzar 《Analog Integrated Circuits and Signal Processing》2001,27(1-2):129-136
A monolithic integrated low-noise amplifier for operation in the 5.8-GHzband is described. Two different versions have been implemented where the biasing wasadapted to allow operation over a different range of supply voltage. At 5-V, theamplifiers gain is about 17-dB, with a noise figure of 4.2-dB and 1-dB compressionpoint at –15-dBm input power. The circuits have been designed utilizing a0.6-micron silicon bipolar production technology, featuring npn transistors with
and
of about20-GHz. 相似文献
62.
The introduction of the double bond in the sphingoid backbone of sphingolipids occurs at the level of dihydroceramide via an NADPH-dependent desaturase, as discovered in permeabilized rat hepatocytes. In the rat, the enzyme activity, which has
now been further characterized, appeared to be mostly enriched in liver and Harderian gland. By means of subcellular fractionation
of rat liver homogenates and density gradient separation of microsomal fractions, the desaturase was localized to the endoplasmic
reticulum. Various detergents were inhibitory to the enzyme, and maximal activities were obtained in the presence of NADPH
and when the substrate was complexed to albumin. In the presence of albumin, the chain length of the fatty acid of the truncated
dihydroceramides hardly affected the activity. Finally, in view of a likely evolutionary relationship between desaturases
and hydroxylases, the formation of hydroxylated intermediates was analyzed. No evidence for their presence was found under
our assay conditions.
In part presented at the Conférence Jacques Monod “Cell lipids: Topology, transport and signalling functions”, Aussois, May
1997 (France); Van Veldhoven, P.P. “Ceramide biosynthesis: Characterisation of the conversion of dihydroceramide to ceramide”.
Contributed equally to this study. 相似文献
63.
64.
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66.
Using the phenomenon of magnetic induction a method for measuring the relative axial and radial displacements between reinforcing
steel and concrete has been developed. For this measuring system a Hall sensor is glued to the surface of the reinforcing
steel to receive the variable magnetic induction caused by a permanent magnet placed within the concrete. 相似文献
67.
Flow phenomena, local heat and mass transfer and pressure drop of corrugated passages in process equipment are examined. Based on a method for measuring local heat and mass transfer, developed in previous investigations, a procedure has been formulated for the determination of local heat and mass transfer in corrugated passages. Using the analogy between heat and mass transfer, this technique allows the determination of heat transfer distributions in any structures with high local resolution. The corresponding pressure drop is presented together with the local and integral heat and mass transfer of different structures. It is shown that differences in heat and mass transfer as well as in pressure drop are due to different flow phenomena which also characterize mixing behaviour. 相似文献
68.
The authors present and test a new method of teaching Bayesian reasoning, something about which previous teaching studies reported little success. Based on G. Gigerenzer and U. Hoffrage's (1995) ecological framework, the authors wrote a computerized tutorial program to train people to construct frequency representations (representation training) rather than to insert probabilities into Bayes's rule (rule training). Bayesian computations are simpler to perform with natural frequencies than with probabilities, and there are evolutionary masons for assuming that cognitive algorithms have been developed to deal with natural frequencies. In 2 studies, the authors compared representation training with rule training; the criteria were an immediate learning effect, transfer to new problems, and long-term temporal stability. Rule training was as good in transfer as representation training, but representation training had a higher immediate learning effect and greater temporal stability. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
69.
This study investigated the effects of organic and colloidal fouling on the removal of a representative micropollutant sulphamethoxazole by two commercially available NF membranes. Alginate, bovine serum albumin and colloidal silica were selected as model foulants to simulate hydrophilic and hydrophobic organic fractions, and colloidal matter that are often found in treated effluent and surface water. Membrane fouling was related to the membrane and foulant characteristics and subsequently the separation behaviour of the micropollutant sulphamethoxazole under different solution pH. On the basis of these results, it was confirmed that membrane fouling is strongly dependent on both the foulant and membrane characteristics. The complex relationship among retention mechanisms, fouling mechanisms and the effects of fouling on retention was systematically delineated. Of the three model foulants selected for this study, colloidal fouling resulted in the most significant reduction in retention of sulphamethoxazole as well as inorganic salts, while flux decline as a result of colloidal fouling was quite moderate. Reduction in retention caused by fouling was attributed to a phenomenon known as cake-enhance concentration polarisation, which was a predominant mechanism of colloidal fouling. In addition, the reported results suggested that the effect of fouling on retention is also membrane pore size dependent. 相似文献
70.
Zusammenfassung. Es wird die Arbeitsweise der klinischen Ethik-Konsultation am Klinikum der Philipps-Universit?t Marburg anhand eines konkreten
Falles dargestellt. Grundlegend für diese Vorgehensweise ist die Theorie und Praxis eines Ethik-Konsildienstes, wie sie am
Medical Center der University of Virginia von J.C. Fletcher, F.G. Miller und J.J. Fins entwickelt wurde.
相似文献