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排序方式: 共有608条查询结果,搜索用时 15 毫秒
81.
Makoto Murakami Ken-ichi Suzuki Hideki Maeda Tetsuo Takahashi Akira Naka Norio Ohkawa Mamoru Aiki 《Optical Fiber Technology》1997,3(4):320-338
Optical amplifier techniques have led to the installation of large-capacity submarine systems and further capacity increases seem likely. This paper reviews the FSA submarine system, which flexibly operates at both 2.5 and 10 Gb/s and offers maximum transmission capacity of 60 Gb/s for commercial use. The system configuration as well as its characteristics and upgradability will be introduced, including measurement results on time-division-multiplexing/wavelength-division-multiplexing (TDM–WDM) transmission at bit rates of 10 and 20 Gb/s using non-return-to-zero or soliton pulses. To further increase transmission capacity, TDM–WDM techniques that permit more than 10 Gb/s signal transmission in each data channel should be developed. Thus, pulse formats, which include non-return-to-zero, return-to-zero, or soliton pulses, and dispersion allocation in transmission fibers are significant issues. We introduce and discuss our recent results from high-speed (10 to 40 Gb/s) TDM–WDM signal transmission experiments with regard to the above aspects. 相似文献
82.
T. Nishijima H. Sekiguchi S. Matsuda N. Shiono 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1997,130(1-4):557-563
A Si pn junction diode and a GaAs Schottky diode were prepared for studying the basic mechanism of charge collection followed by high energy charged particle incidence in order to improve the resistance against single event upset. A 2 μm wide and 20 μm long rectangular Al electrode attached to a circular Al electrode with a 50 μm diameter was made on a 2.5 μm thick epilayer (minority carrier density 2 × 1015 /cm3). Both a Schottky electrode of Al (5 μm × 110 μm) and two ohmic electrodes of AuGe/Ni (110 μm × 110 μm) were made on a 2 μm thick epilayer (7.3 × 1015 /cm3) grown on a semi insulator GaAs substrate (1 × 107 Ω cm). The internal device structure was examined by the IBIC (Ion Beam Induced Charge) method using a 2 MeV He+ ion microbeam. IBIC images clearly show an Al electrode, the SiO2, and an epilayer. These results were then used to improve the qualities of the test diodes. 相似文献
83.
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85.
Seiji Isoda Masaki Tsuji Masayoshi Ohara Akiyoshi Kawaguchi Ken-ichi Katayama 《Polymer》1983,24(9):1155-1161
The crystal structure of β-form poly(p-xylylene) is analysed starting from a high-resolution image of a single crystal of this polymer. The high-resolution image corresponding to the projection of molecules onto the ab-plane along the chain axis shows clearly the mutual position of each molecule in a unit cell. The molecules are aligned wavily in the direction along the a-axis and the rough positions of their centres in a unit cell can be determined from the image. The refinement of the structure is carried out by the usual least-squares method using the intensities of electron and X-ray diffractions. The space group of the β-form is trigonal, P3, and the lattice dimensions are a=2.052 nm, c=0.655 nm and γ=120°. The unit cell contains 16 molecules and one of them is considered to occupy statistically one of three equivalent orientations so as to satisfy the P3 symmetry. 相似文献
86.
Two studies examined the effects of an apology on a victim's aggression and explored the psychological mechanisms underlying such effects. In Study 1, female undergraduates were psychologically harmed and then received an apology by another female student. In Study 2, male undergraduates were asked to role play a victim in a hypothetical harm situation. Results indicate that when the harm-doers apologized, as opposed to when they did not, the victim-subjects refrained from severe aggression against them. Regression analyses suggested that such aggression-inhibitory effects of an apology were mediated by impression improvement, emotional mitigation, and reduction in desire for an apology within the victims. It was also found that when the harm was severe, such effects of an apology on aggression were attenuated. The more severe the harm is, the more extensive of an apology may be needed to alleviate the victim's anger and aggression. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
87.
Hakoshima Toshio; Toda Shoji; Sugio Shigetoshi; Tomita Ken-ichi; Nishikawa Satoshi; Morioka Hiroshi; Fuchimura Kayoko; Kimura Tsuyoshi; Uesugi Sei-ichi; Ohtsuka Eiko; Ikehara Morio 《Protein engineering, design & selection : PEDS》1988,2(1):55-61
Recognition by ribonuclease T1 of guanine bases via multidentatehydrogen bonding and stacking interactions appears to be mediatedmainly by a short peptide segment formed by one stretch of aheptapeptide, Tyr42-Asn43-Asn44-Tyr45-Gly46-Gly47-Phe48. Thesegment displays a unique folding of the polypeptide chainconsistingof a reverse turn, Asn44-Tyr45-Glu46-Gly47, stabilized by ahydrogen-bond network involving the side chain of Asn44, themain-chain atoms of Asn44, Gly47 and Phe48 and one water molecule.The segment is connected to the C terminus of a ß-strandand expands into a loop region between Asn43 and Ser54. Lowvalues for the crystallographic thermal parameters of the segmentindicate that the structure has a rigidity comparable to thatof a ß-pleated sheet. Replacement of Asn44 with alanineleads to a far lower enzymatic activity and demonstrates thatthe side chain of Asn44 plays a key role in polypeptide foldingin addition to a role in maintaining the segment structure.Substitution of Asn43 by alanine to remove a weak hydrogen bondto the guanine base destabilized the transition state of thecomplex by 6.3 kJ/mol at 37°C. In contrast, mutation ofGlu46 to alanine to remove a strong hydrogen bond to the guaninebase caused a destabilization of the complex by 14.0 kJ/mol.A double-mutant enzyme with substitutions of Asn43 by a histidineand Asn44 by an aspartic acid, to reproduce the natural substitutionsfound in ribonuclease Ms, showed an activity and base specificitysimilar to that of the wild-type ribonuclease Ms. The segmenttherefore appears to be well conserved in several fungal ribonucleases. 相似文献
88.
Summary It was found that radical polymerization occurs when the mixture of p-methoxystyrene and styrene in the presence of electron acceptors is photoexcited in basic solvents. Concomitantly, p-methoxystyrenestyrene co-dimers: trans-1-(4-methoxyphenyl)-2-phenyl-cyclobutane and 1-(4-methoxyphenyl)-1,2,3,4-tetrahydronaphthalene are produced. From the results of some polymerization runs and the co-dimer structure, it is considered that the linear co-dimer cation radical is the common precursor for both radical polymerization and cationic dimerization, and the radical polymerization is initiated by its radical end. 相似文献
89.
Human placenta gangliosides 总被引:2,自引:0,他引:2
Takao Taki Ken-ichi Matsuo Kaname Yamamoto Toshiko Matsubara Akira Hayashi Tadayuki Abe Makoto Matsumoto 《Lipids》1988,23(3):192-198
Gangliosides extracted from human placenta were composed of four major components (G1–G4), which were purified by silica beads
column chromatography. The structures of these gangliosides were analyzed by exoglycosidase treatments, 400 MHz proton magnetic
resonance spectroscopy and gas chromatography-mass spectrometry and were concluded to be as follows:
Gangliosides containing more than 10 sugar residues were observed in addition to the above four major components. But ganglio-series
gngliosides were undetectable in the placenta. 相似文献
90.