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排序方式: 共有3709条查询结果,搜索用时 346 毫秒
31.
An improved T -Ω method that can analyze magnetic fields produced not only by eddy currents but also by magnetizing currents is proposed. The method is applied to the analysis of 3-D eddy-current models with holes. The usefulness of the method is investigated by comparing calculated results with measured results and with results obtained by the A -Φ method. The T -Ω method has the advantage that the CPU time can be considerably reduced when most of the analyzed region is current-free and the eddy current flows two-dimensionally. The method is especially effective when the shape of the winding is simple and the distribution of magnetizing current is known beforehand. It is not effective when most of the analyzed region is current-carrying 相似文献
32.
Komoda M. Kawashima T. Arakane M. Aihara M. Fujiwara Y. Shinagawa J. 《Power Delivery, IEEE Transactions on》1991,6(2):541-545
A cable fault location instrument based on the detection of traveling wave currents was developed. It is different from the conventional pulse radar method based on voltage detection. Measurement is automated, and the distance to the fault point is displayed by merely pushing a switch. In a branched or crossbonded line, the fault point can be located without interference from the branched or the crossbonded point. Tests performed in both real and simulated lines confirmed the practical utility of this instrument 相似文献
33.
34.
This study was undertaken to compare the calcium-independent phospholipase A2 (PLA2) activities in the cytosols of twelve rat tissues and to determine whether their activities were distinct. 1-O-Alk-1′-enyl-2-[14C]-oleoyl-sn-glycero-3-phosphocho-line (PlsC) and 1-O-Alk-1′-enyl-2-[14C]oleoyl-sn-glycero-3-phosphethanolamine (PlsE) were synthesized and used as substrates, instead of phosphatidyl compounds, to exclude
hydrolysis by cytosolic PLA1 activity that could be present in some of the cytosolic preparations. For each tissue, we examined substrate specificity,
pH optimum, and effect of adenosine triphosphate (ATP) and ATP analogues. PLA2 activity was detected in eleven out of the twelve issues examined. Based on substrate specificity and pH optimum, cytosolic
calcium-independent PLA2 were classified in three groups. The first group, which included PLA2 from small intestine, stomach and spleen, had the highest specific activity with PlsC as substrate (1253, 309 and 75 nmol/mg
protein/hour, respectively) and an optimal pH at 6.5. Activity with PlsE as substrate was much lower (20–37%) than with PlsC.
The second group of PLA2 activities included the cytosolic activities from thymus, lung, liver and pancreas that showed lower specific activities
for both substrates (14–23 nmol/mg protein/hour with PlsC) and had a broader optimal pH range of 6.1 to 7.5. The cytosols
from brain, kidney, heart and muscle comprised the third PLA2 group that was found to have a higher specific activity with PlsE (5–20 nmol/mg protein/hour) than PlsC and an optimal pH
range from 7.4 to 7.9. Since the highest specific activity was found in the cytosol from small intestine, this PLA2 was examined further. PLA2 activity was found to be equally distributed in the cytosol of the submucosal portion of duodenum, jejunum and ileum with
an optimal pH of 6.1 and a 5-fold higher activity with PlsC than PlsE as substrate. Moreover, this PLA2 activity was inhibited by treatment with detergents. These results indicate the presence in the submucosal portion of the
intestine of a calcium-independent cytosolic PLA2 with a high specific activity toward PlsC and properties distinct from those described for the PLA2 found in the intestinal brush-border. 相似文献
35.
Characterization of C-S-H from Highly Reactive β-Dicalcium Silicate Prepared from Hillebrandite 总被引:1,自引:1,他引:0
Yoshihiko Okada Hideki Ishida Kaori Sasaki J. Francis Young Takeshi Mitsuda 《Journal of the American Ceramic Society》1994,77(5):1313-1318
β-dicalcium silicate synthesized by thermal dissociation of hydrothermally prepared hillebrandite (Ca2 (SiO3 )(OH)2 ) exhibits extremely high hydration activity. Characterization of the hydrates obtained and investigation of the hydration mechanism was carried out with the aid of trimethylsilylation analysis, 29 Si magic angle spinning nuclear magnetic resonance, transmission electron microscopy selected area electron diffraction, and XRD. The silicate anion structure of C-S-H consisted mainly of a dimer and a single-chain polymer. Polymerization advances with increasing curing temperature and curing time. The C-S-H has an oriented fibrous structure and exhibits a 0.73-nm dreierketten in the longitudinal direction. On heating, the C-S-H dissociates to form β-C2 S. The temperature at which βC2 S begins to form decreases with increasing chain length of the C-S-H or as the Ca/Si ratio becomes higher. The high activity of β-C2 S is due to its large specific surface area and the fact that the hydration is chemical-reaction-rate-controlled until its completion. As a result, the hydration progresses in situ and C-S-H with a high Ca/Si ratio is formed. 相似文献
36.
37.
Yi Fang Vu Anh Pham Takeshi Matsuura J. P. Santerre Roberto M. Narbaitz 《应用聚合物科学杂志》1994,54(12):1937-1943
Polyethersulfone (PES) membranes using different evaporation periods were fabricated by the phase-inversion method. Pervaporation experiments were conducted for chloroform/water mixtures to determine the selectivity of the PES membranes. It was found that chloroform could be concentrated in the permeate from chloroform/water binary feed mixtures by PES membranes prepared using longer evaporation periods, and that the selectivity of PES membranes in pervaporation could be reversed by shorter evaporation periods. This study also showed that by adding surface-modifying macromolecules (SMM) up to 1 wt % into the casting solution, chloroform enrichment in the permeate could be increased by 50%. Chloroform enrichment increased with increasing SMM concentration until an optimal value, after which the enrichment decreased. © 1994 John Wiley & Sons, Inc. 相似文献
38.
Fujiwara T. Ito M. Kasami T. Kataoka M. Okui J. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1991,37(2):379-384
The problem of distributing a Cartesian product file on multiple disks to maximize the parallelism for partial match queries is addressed. C. Faloutsos et al. (1989) have proposed an allocation method for Cartesian product files on multiple disks by using linear error-correcting codes. The performance of the allocation method is analyzed. Some conditions under which the allocation method is strictly optimal for queries with a given number of unspecified attributes are presented. A necessary and sufficient condition for a linear code to give a strictly optimal allocation method is discussed. Formulas for the average response time on queries with w unspecified attributes, denoted T w, in terms of the weight distribution of the code or its dual code, and formulas for the average response time T on all queries, are given. Several examples whose average response times T w or T are close to theoretical lower bounds are presented 相似文献
39.
A case of Waldenstr?m's macroglobulinemia (WM) (IgM-kappa type) associated with acute-onset demyelinating peripheral neuropathy is reported. A 49-year-old woman was admitted to our hospital because of general fatigue and recurrent syncope attacks. She was treated with vincristine, cyclophosphamide, epirubicin and prednisolone. By 10th hospital day, her clinical condition improved and serum viscosity was reduced. However, on the 21st hospital day, she suffered from rapidly progressive writing and gait disturbance. Neurological examination showed muscular atrophy and weakness in the distal part of four extremities. Deep tendon reflexes were diminished. There was no sensory deficit. Cerebrospinal fluid was normal. Anti-myelin associated glycoprotein activity of her serum was negative. Both motor and sensory nerve conduction velocities were markedly decreased. Biopsy of sural nerve revealed marked demyelination and onion bulb formation. There was IgM deposition on myelin sheath. Minimal axonal changes excluded the possibility of vincristine neuropathy. Plasmapheresis improved her symptoms, but nerve conduction velocities remained unchanged. Polyneuropathy associated with WM is usually gradual onset and sensory dominant. In this case, associated neuropathy was acute onset, progressive and motor dominant. This type of neuropathy in patients with WM is very rare. 相似文献
40.