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排序方式: 共有740条查询结果,搜索用时 187 毫秒
41.
Giant room-temperature magnetoresistance in single-crystal Fe/MgO/Fe magnetic tunnel junctions 总被引:3,自引:0,他引:3
The tunnel magnetoresistance (TMR) effect in magnetic tunnel junctions (MTJs) is the key to developing magnetoresistive random-access-memory (MRAM), magnetic sensors and novel programmable logic devices. Conventional MTJs with an amorphous aluminium oxide tunnel barrier, which have been extensively studied for device applications, exhibit a magnetoresistance ratio up to 70% at room temperature. This low magnetoresistance seriously limits the feasibility of spintronics devices. Here, we report a giant MR ratio up to 180% at room temperature in single-crystal Fe/MgO/Fe MTJs. The origin of this enormous TMR effect is coherent spin-polarized tunnelling, where the symmetry of electron wave functions plays an important role. Moreover, we observed that their tunnel magnetoresistance oscillates as a function of tunnel barrier thickness, indicating that coherency of wave functions is conserved across the tunnel barrier. The coherent TMR effect is a key to making spintronic devices with novel quantum-mechanical functions, and to developing gigabit-scale MRAM. 相似文献
42.
Vergleich von Hochofenbetriebsergebnissen mittels Leistungs-Faktor-Definition. Bestimmung der Lage und Form der Schmelzlinie im Hochofen durch Betriebsdaten. Wärmeeinbringen durch Blasform und deren Übertragung durch Konvektion und Strahlung. Einfluß der Wärmebedingungen im Unterofen auf die Lage der Schmelzlinie. Vergleich und Überprüfung der Modellprofile durch Betriebsmessungen. Einfluß verschiedener Unterofenparameter auf Hochofenbetrieb und Schmelzlinie. Schmelzgeschwindigkeit bei W- und ∧-Profilen in Abhängigkeit der Strahlungstemperatur. Untere kritische Höhenlage der Schmelzlinie und dynamisches Verhalten der Schmelzlinie. 相似文献
43.
M. Matsuoka T. Hayasaka Y. Fukushima Y. Honda 《International journal of remote sensing》2013,34(2):221-248
Land cover is classified over East Asia using 250‐m Moderate Resolution Imaging Spectroradiometer (MODIS) land surface reflectance, MODIS snow cover and Operational Linescan System (OLS) human settlement data. The classification method includes a decision tree classification scheme that considers 11 kinds of land surface features derived from the OLS product and the time series of two MODIS products in 2000. The decision tree was defined manually based on the experiment because of insufficient training data, ease of tuning by visual interpretation, and extensibility to further research. The resulting classification is compared to three kinds of reference data, i.e. MODIS land cover product, Chinese digital land cover map, and Chinese census. The land cover classification can be input into a hydrological model applied to the Yellow River in China. 相似文献
44.
Watanabe I. Torikai T. Makita K. Fukushima K. Uji T. 《Electron Device Letters, IEEE》1990,11(10):437-438
Impact ionization rates for electrons and holes in (100) Al0.48In0.52As were determined from photomultiplication measurements using AlInAs/GaInAs p+-i-n diodes grown by metalorganic vapor phase epitaxy (MOVPE). The impact ionization-rate ratio was derived as being 2.0~3.5 over the electric field range from 400 to 650 kV/cm. Ionization rates were found to be smaller than those previously reported. These results could be useful for designing AlInAs/GaInAs superlattice avalanche photodiodes with an electron-initiated configuration 相似文献
45.
In this short paper,we have treated the aerodynamic performance of micro downwind rotor with coning soft blades experimentally.The test wind rotor has the tip diameter of 1.5 m and three two-dimensional NACA0018 blades of 0.15 m chord whose material is light,soft and pliable foam plastic for perfect safety.From the wind tunnel test,it is realized that the performance is manageable by the coning angle of the rotor blade.In the present case,an improvement of the performance in lower wind speeds is achieved by... 相似文献
46.
Yasumasa Fukushima 《Polymer Bulletin》2000,45(3):237-244
Summary
Four sequential copolypeptides poly(X-Gly-Gly) with X being Ala, Tyr, Gln, or Leu were prepared as a model of glycine-rich
sequence of dragline spider silk produced by Nephila clavipes and their secondary structures in the solid state were characterized by FT-IR spectroscopy. Poly(Tyr-Gly-Gly), poly(Gln-Gly-Gly),
and poly(Ala-Gly-Gly) form the β-sheet structures, whereas poly(Leu-Gly-Gly) existed as a disordered conformation as a cast
film from formic acid. These results indicated that X-Gly-Gly sequences with Tyr, Gln, and Ala could contribute to the formation
of the β-sheet structure in glycine-rich sequence.
Received: 5 August 2000/Accepted: 24 August 2000 相似文献
47.
Michihiro Miyake Hiroyuki Yamaguchi Takashi Suzuki 《Journal of Materials Science》1990,25(12):5096-5100
The swelling and dehydration characteristics of Mn2+, Ni2+, Cu2+ and Zn2+ ion-substituted taeniolites with the exchange ratios of 85% and 78% have been investigated by high-temperature X-ray diffractometry, thermogravimetry-differential thermal analysis and calorimetry. The transition metal forms are the swelling states with two water-molecule layers at room temperature and a relative humidity of 70%, and their dehydration processes to the swelling states with a half water-molecule layer were concluded from the experimental results, to depend on the kind of the interlayer cations. In particular, the new swelling state with three-quarters water-molecule layers, showing a rational series of the basal reflections, was discovered to exist stably in the dehydration processes of manganese and nickel forms. The heat of swelling with water attains a maximum at a temperature corresponding to the appearance of the swelling state with a half water-molecule layer. The calorific value for the copper form was measured to be much larger than those for manganese, nickel and zinc forms. 相似文献
48.
Yasuyuki Koyama Ryuzo Takagi Yasuhiko Iwadate Kazuko Fukushima 《Journal of Alloys and Compounds》1997,260(1-2):75-79
A phase diagram of the EuCl2---NaCl system was determined by differential scanning calorimetry (DSC) and the activity coefficients of EuCl2 and NaCl in this system were estimated under some assumptions. According to DSC measurement, it was found that there were two phase transitions at 1123.9 K and 1016.8 K. In order to specify the melting point of EuCl2 we did Raman spectroscopy experiments. Thus, the melting point of EuCl2 was evaluated to be 1016.8 K which was detected as the lower peak in the DSC curve. Raman spectroscopy of this system suggested that complex species were not formed clearly in the EuCl2 poor system and the estimated activity coefficients of EuCl2 also supported this suggestion. 相似文献
49.
Yuki Nakashima You Zhou Keisuke Tanabe Souhei Arima Kiyoshi Hirao Tatsuki Ohji Norimitsu Murayama Manabu Fukushima 《Journal of the American Ceramic Society》2023,106(2):1139-1148
Silicon nitride (Si3N4) was prepared from silicon by a sintered reaction-bonded silicon nitride method using yttria and magnesia as sintering additives. Post-sintering (PS) of nitrided compacts was carried out at 1850°C under a nitrogen pressure of 1 MPa. Effect of PS time on microstructure and dielectric breakdown strength (DBS) of the prepared Si3N4 ceramics was evaluated. The DBS was measured using specimens with four different thicknesses (0.30, 0.20, 0.10, and 0.05 mm) in order to examine the thickness dependence. The porosity of the sintered Si3N4 decreased by prolonging the PS time, and the full density could be achieved at the PS time of over 6 h. After full densification, rod-like β-Si3N4 grains grew up, and their maximum grain size increased from 45.1 to 154.7 μm by prolonging the PS time from 6 to 48 h. The DBS of the thick Si3N4 substrates (0.30 mm) showed little variation from 35.4 to 47.0 kV/mm, regardless of the PS time. On the other hand, that of the thin ones (0.05 mm) dramatically decreased from 99.5 to 9.8 kV/mm with increased the PS time from 6 to 48 h. Because the DBS sharply decreased at the thin substrate sintered for longer time in which some large-elongated grains might span the substrate thickness-wise throughout, it was inferred that the interface between β-Si3N4 grains and grain boundary phase/intergranular glassy films might be a path of the dielectric breakdown. 相似文献
50.
Various four-base codons have been shown to work for the introduction of non-natural amino acids into proteins in an Escherichia coli cell-free translation system. Here, a four-base codon-mediated non-natural mutagenesis was applied to a eukaryotic rabbit reticulocyte cell-free translation system. Mutated streptavidin mRNAs containing four-base codons were prepared and added to a rabbit reticulocyte lysate in the presence of tRNAs that were aminoacylated with a non-natural amino acid and had the corresponding four-base anticodons. A Western blot analysis of translation products indicated that the four-base codons CGGU, CGCU, CCCU, CUCU, CUAU, and GGGU were efficiently decoded by the aminoacyl-tRNAs having the corresponding four-base anticodons. In contrast, the four-base codons AGGU, AGAU, CGAU, UUGU, UCGU, and ACGU were not decoded. The stop codon-derived four-base codons UAGU, UAAU, and UGAU were found to be inefficient, whereas the amber codon UAG and opal codon UGA were efficient for the incorporation of non-natural amino acids. The application of the expanded genetic code in a eukaryotic cell-free system opens the possibility of a four-base codon-mediated incorporation of non-natural amino acids into proteins in living eukaryotic cells. 相似文献