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排序方式: 共有745条查询结果,搜索用时 15 毫秒
91.
92.
Intensity fluctuations for two types of 1.3 ?m InGaAsP laser are measured and calculated based on device structural and material parameters and are found to be in good agreement with the quantum-noise-limited level. 相似文献
93.
As superconducting generators have a number of advantages, the investigations for such machines have actively been carried out throughout the world. In the superconducting generator, it is very important to support the field winding and to protect it from quenching. On the other hand, since the armature winding is of air core, the evaluation of eddy current loss in the winding and the way it is supported arc inevitable. Thus, the magnetic fields and the electromagnetic forces acing on both the field and the armature windings at the early stages of the machine design should be known. In previous papers the transient behavior of magnetic fields and electromagnetic forces acting on the windings of a superconducting generator based on a computer simulation for a sudden 3-phase fault have been discussed in part. However, the behavior of magnetic fields and electromagnetic forces during transient period is very complicated and many calculations are required to determine their maximum values. In this paper, for practical use at the early stages of the machine design, approximate expressions are derived to calculate the maximum values of the magnetic fields and electromagnetic forces on the windings in the case of a 3-phase fault. To check these expressions numerically, a 1000-MVA superconducting generator was conceptually designed. The numerical results obtained by using these expressions agree well with the computer simulation results. 相似文献
94.
T Kawamata T Taniguchi H Mukai M Kitagawa T Hashimoto K Maeda Y Ono C Tanaka 《Canadian Metallurgical Quarterly》1998,18(18):7402-7410
A possible role for a protein kinase, PKN, a fatty acid-activated serine/threonine kinase with a catalytic domain homologous to the protein kinase C family and a direct target for Rho, was investigated in the pathology of Alzheimer's disease (AD) using a sensitive immunocytochemistry on postmortem human brain tissues and a kinase assay for human tau protein. The present study provides evidences by light, electron, and confocal laser microscopy that in control human brains, PKN is enriched in neurons, where the kinase is concentrated in a subset of endoplasmic reticulum (ER) and ER-derived vesicles localized to the apical compartment of juxtanuclear cytoplasm, as well as late endosomes, multivesicular bodies, Golgi bodies, secretary vesicles, and nuclei. In AD-affected neurons, PKN was redistributed to the cortical cytoplasm and neurites and was closely associated with neurofibrillary tangles (NFTs) and their major constituent, abnormally modified tau. PKN was also found in degenerative neurites within senile plaques. In addition, we report that human tau protein is directly phosphorylated by PKN both in vitro and in vivo. Thus, our results suggest a specific role for PKN in NFT formation and neurodegeneration in AD damaged neurons. 相似文献
95.
Kazuhisa Shobu Eiji Tani Morito Akiyama Tadahiko Watanabe 《Journal of the American Ceramic Society》1996,79(2):544-546
High-temperature fracture behavior of melt-infiltrated SiC-Mo(AI,Si)2 composites was studied. The composites exhibited moderate strength up to ∼1600°C under a fast loading rate. The softening of the Mo(Al,Si)2 phase determined dominantly the temperature over which the strength decreased. The composite with finer microstructure revealed a higher level of strength over the whole temperature range. At 1580°C, however, the composites revealed distinct strength degradation at a reduced loading rate. 相似文献
96.
97.
Yamada Jun-Ichi Machida Susumu Mukai Takaaki Kano Hiroyuki Sugiyama Koichi 《Electronics letters》1979,15(19):596-597
Modulation experimenting on a buried-stripe (b.s.) InGaAsP laser emitting at 1.3 ?m was carried out up to 2 Gbit/s. The b.s. laser is free from relaxation oscillation, which degrades modulated optical pube waveforms, especially at high data rates. The repeater gain of 1.6 Gbit/s transmission systems is improved by 9 dB compared with previously reported experiments. Modulation characteristics up to 2 Gbit/s are reported. 相似文献
98.
Phytochelatins (PCs) are heavy metal-binding peptides that play important roles in the detoxification of toxic heavy metals and the regulation of intracellular concentrations of essential metals in eukaryotes, including higher plants, fungi, and microalgae. Recently, PC synthase genes in higher plants and fission yeast have been identified and characterized, enabling molecular biological studies to unravel the mechanisms underlying PC synthesis. Moreover, recent routine database searches have unexpectedly identified genes that are similar to plant PC synthase genes in the genomes of worms and some prokaryotes. In this review, we introduce these recent advances in our understanding of the molecular mechanisms for PC biosynthesis and functions in order to supply basic information about the unique and attractive peptides applicable to various fields. 相似文献
99.
Baseband signal-to-noise-ratio characteristics in an AlGaAs laser preamplifier and a linear repeater system were studied theoretically and experimentally. The AlGaAs laser preamplifier improved the minimum detectable power by 1.6 dB over the level achieved by direct detection with an Si APD. 37 dB regenerative repeater gain was experimentally obtained in the system with two optical repeaters at 100 Mbit/s data rate. 相似文献
100.