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排序方式: 共有605条查询结果,搜索用时 15 毫秒
51.
Ichitaro Ogawa Hisayoshi Yoshida Kazuo Kobayashi Michio Inagaki 《Journal of Materials Science》1985,20(2):414-420
Phenolic resins and the benzene-soluble fraction of a coal tar pitch were mixed in a solvent (pyridine) and carbonized at 600° C in a gold tube under a pressure of 30 MPa. Yields, optical textures and graphitizabilities of the carbons were studied. Large carbon yields (>80%) were obtained from sealed tubes under pressure (closed system). In open tubes under pressure (open system), only slight improvements in carbon yields were observed. As the resin content in the starting mixtures increased, the optical texture of the resultant carbons decreased from coarse mosaic to isotropic through intermediates with a gradual decrease in size of mosaic units. These intermediate optical textures occurred with a wider range of resin content under pressure than under atmospheric pressure, especially from closed systems. Changes in structural parameters of the carbons after the 2800° C treatment corresponded to the changes in optical texture with resin content. 相似文献
52.
Kuwatsuka H. Mikawa T. Miura S. Yasuoka N. Tanahashi T. Wada O. 《Photonics Technology Letters, IEEE》1990,2(1):54-55
An AlxGa1-xSb avalanche photodiode (APD) with an Al composition of 0.05 has been fabricated and tested. The measured gain-bandwidth (GB) product of the highly doped diode is 90 GHz. Such a large GB product has never been previously achieved by any APD materials sensitive in the long-wavelength region. This suggests the advantage of the AlxGa1-xSb material system for very high-speed operation 相似文献
53.
An avalanche photodiode (APD) designed by using quasi-ionization rates in InP and InGaAs is described. The structure has a δ-doped layer in an InP window layer. The heterointerface electric field is investigated and determined to prevent the tunneling current and carrier multiplication in InGaAs. The gain bandwidth (GB) product of the δ-doped APD is analyzed by R.B. Emmons's (1967) p-i-n electric field method. The highest GB product is 160 GHz 相似文献
54.
55.
A study of manipulator with passive revolute joint 总被引:1,自引:1,他引:0
In this article, equations of motion of a manipulator, whose mechanism has a passive revolute joint, are derived in consideration
of the characteristics of driving source. Considering the fi nal condition of displacement and velocity of the passive joint,
trajectories of velocity for energy saving are calculated by iterative dynamic programming. And the dynamic characteristics
of manipulator control based on the trajectory for energy saving are analyzed theoretically and investigated experimentally.
This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January
31–February 2, 2008 相似文献
56.
Michio Niwano Hideo Kitamura 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1985,234(2):388-393
A new type of undulator greatly improved in tunability as compared with a usual undulator, is proposed. The undulator has a composite magnetic field which is a linear superposition of two sinusoidally varying fields with different spatial periods. The wavelength can be changed by varying the field strength of the longer-period component while keeping that of the shorter-period component at the highest possible value. Numerical calculations of the spectral brightness were carried out. The proper ratios between the two spatial periods were found to be 3:1, 5:1 and 7:1. 相似文献
57.
Identification of yeast strains isolated from marcha in Sikkim, a microbial starter for amylolytic fermentation 总被引:1,自引:0,他引:1
Tsuyoshi N Fudou R Yamanaka S Kozaki M Tamang N Thapa S Tamang JP 《International journal of food microbiology》2005,99(2):135-146
Marcha or murcha is a traditional amylolytic starter used to produce sweet-sour alcoholic drinks, commonly called jaanr in the Himalayan regions of India, Nepal, Bhutan, and Tibet (China). The aim of this study was to examine the microflora of marcha collected from Sikkim in India, focusing on yeast flora and their roles. Twenty yeast strains were isolated from six samples of marcha and identified by genetic and phenotypic methods. They were first classified into four groups (Group I, II, III, and IV) based on physiological features using an API test. Phylogenetic, morphological, and physiological characterization identified the isolates as Saccharomyces bayanus (Group I); Candida glabrata (Group II); Pichia anomala (Group III); and Saccharomycopsis fibuligera, Saccharomycopsis capsularis, and Pichia burtonii (Group IV). Among them, the Group I, II, and III strains produced ethanol. The isolates of Group IV had high amylolytic activity. Because all marcha samples tested contained both starch degraders and ethanol producers, it was hypothesized that all four groups of yeast (Group I, II, III, and IV) contribute to starch-based alcohol fermentation. 相似文献
58.
Yamamoto T Mukai K Yamashita H Kubota M Fukuda S Kurimoto M Tsujisaka Y 《Journal of Bioscience and Bioengineering》2005,100(2):212-215
Random mutation by error-prone PCR was introduced into kojibiose phosphorylase from Thermoanaerobacter brockii ATCC35047. One thermostable mutant enzyme, D513N, was isolated. The D513N mutant enzyme showed an optimum temperature of 67.5-70 degrees C (the wild type, 65 degrees C), and thermostability up to 67.5 degrees C (the wild type, up to 60 degrees C). The half-lives of D513N were estimated to be 135 h at 60 degrees C, 110 min at 70 degrees C and 6 min at 75 degrees C, respectively. They were about 1.6-fold, 7-fold and 6-fold longer than those of the wild-type enzyme, respectively. 相似文献
59.
Hiroyuki Fujiwara Tetsuya Kaneko Michio Kondo 《Solar Energy Materials & Solar Cells》2009,93(6-7):725-728
In heterojunction solar cells consisting of hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si), suppression of epitaxial growth at the heterointerface is found to be crucial to achieve high solar cell efficiencies. In order to avoid the epitaxial growth, wide-gap hydrogenated amorphous silicon oxide (a-SiO:H) has been applied to the heterojunction solar cells. We have fabricated a-SiO:H/c-Si solar cells using n-type and p-type c-Si substrates and demonstrated that incorporation of the a-SiO:H i layer prevents the harmful epitaxial growth at the heterointerface completely. 相似文献
60.
Vladimir Švrček Hiroyuki Fujiwara Michio Kondo 《Solar Energy Materials & Solar Cells》2009,93(6-7):774-778
We demonstrate that the electrochemical etching and pulverization of porous silicon films allow the fabrication of boron- and phosphorous-doped freestanding silicon nanocrystals (Si-ncs). The presence of boron in freestanding Si-ncs was confirmed from low-temperature photoluminescence (PL) analysis. The temperature dependence of PL for both types of doped Si-ncs reveals two PL bands due to the quantum confinement effect and surface state defects. Blending of Si-ncs into poly[methoxy-ethylexyloxy-phenylenevinilene] polymer leads to suppression of the PL band originated from surface states. More importantly, those blends showed a photoconductivity response under illumination AM1.5 at room temperature. 相似文献