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61.
以N-异丙基丙烯酰胺(NIPAAm)为单体,合成了NIPAAm均聚凝胶。研究了25℃时它们在乙醇水溶液中的溶胀平衡。实验发现:当乙醇浓度约为12%时,少量乙醇的进一步加入将使溶涨的凝胶突然剧烈收缩,表明NIPAAm凝胶在乙醇水溶液中有不连续体积相变。随着乙醇不断加入,凝胶又重新溶涨。结合“自由体积”概念,利用UNIQUAC模型的关联和预报了NIPAAm凝胶在乙醇-水溶液中的这种溶涨行为。 相似文献
62.
Optimizing continuous annealing of interstitial-free steels for improving deep drawability 总被引:1,自引:0,他引:1
Pasi Juntunen Pentti Karjalainen Dierk Raabe Gerd Bolle Tero Kopio 《Metallurgical and Materials Transactions A》2001,32(8):1989-1995
The crystallographic textures and the resulting plastic anisotropy of five interstitial-free (IF) steels with different carbon
equivalents and Nb and Ti microalloying content have been investigated. The steels were industrially hot rolled, cold rolled,
annealed, and finally hot-dip galvanized. An alternative heat treatment of the cold rolled samples was conducted in laboratory
scale using parameters close to those in industry-scale continuous annealing lines. The anisotropy parameters were both measured
and predicted on the basis of the measured texture data. The calculated
values were corrected by using functions that were fitted to the experimental data. It was found that for a given hot and
cold rolling state even minor changes in the annealing conditions can improve the anisotropy parameter
by up to 13 pct. Increase in recrystallization texture and improvement of the resulting anisotropy parameters are discussed
in terms of partial transformation of ferrite to austenite in the intercritical regime. 相似文献
63.
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
64.
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
65.
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68.
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
69.
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
70.
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