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排序方式: 共有609条查询结果,搜索用时 15 毫秒
1.
Keizo Uematsu Masayori Miyashita Jin-Young Kim Zenji Kato Nozomu Uchida 《Journal of the American Ceramic Society》1991,74(9):2170-2174
Green bodies prepared by compaction of alumina granules were made transparent by an immersion liquid technique, and the internal structure was characterized with an optical microscope to study the effect of forming pressure on the internal structure. Clear images obtained by the technique provide more detailed information than other existing methods for structures ranging from one to tens of micrometers. Intergranular pores were present between unfractured granules. Their sizes and concentration tended to decrease with increasing forming pressure. However, pores were clearly present even in the green body prepared at 600 MPa. A rod- and needlelike feature was also found and was concluded to correspond to a high-density region. The significance of large pores and high-density regions on processing as well as the details of the technique is discussed. 相似文献
2.
3.
H Koga K Hayashi E Taketomi S Matsunaga S Yashiki T Fujiyoshi S Sonoda T Sakou 《Canadian Metallurgical Quarterly》1996,21(4):469-473
STUDY DESIGN: The present study analyzed the restriction fragment length polymorphism patterns of alpha 2(XI) collagen, bone morphogenetic protein-2, alkaline phosphatase, and tumor necrosis factor-alpha genes in patients with ossification of the posterior longitudinal ligament. This study investigates the genetic polymorphism of bone-induced factors in patients with ossification of the posterior longitudinal ligament and compares it with healthy control subjects. OBJECTIVES: To clarify the genetic markers linked to ossification of the posterior longitudinal ligament. SUMMARY OF BACKGROUND DATA: Ossification of the posterior longitudinal ligament is a genetic disease associated with abnormal calcium metabolism involving the posterior longitudinal ligament. Previous genetic studies have not identified the pathologic mechanism of ossification of the posterior longitudinal ligament. Histopathologic studies of ossification of the posterior longitudinal ligament and the animal model, the spinal hyperostotic mouse, have revealed an increase in Type XI collagen and bone morphogenetic protein-2 expression. METHODS: Eighteen Japanese patients with ossification of the posterior longitudinal ligament and 51 healthy, unrelated control subjects were investigated for the restriction fragment length polymorphism patterns of COL11A2, bone morphogenetic protein-2, alkaline phosphatase, and tumor necrosis factor-alpha, genes with various restriction endonucleases. RESULTS: The gene frequencies of COL11A2 obtained with BamHl (10.0 kb fragment) and HindIII (19.0 kb fragment) observed in patients with ossification of the posterior longitudinal ligament were higher compared with control subjects (0.43 and 0.14, respectively). These differences were statistically significant (BamHl P = 0.018; Hindlll P = 0.046). Two new restriction fragment length polymorphism patterns were detected of the bone morphogenetic protein-2 gene with Mspl and Taql and one already known restriction fragment length polymorphism pattern of the tumor necrosis factor-alpha gene with Ncol. However, they were not significantly different from the control subjects. CONCLUSIONS: Seven restriction fragment length polymorphisms of COL11A2 gene were identified. Two of them (BamHl, 10.0/10.0 kb genotype; HindIII, 19.0/19.0 kb genotype) were significantly different in patients with ossification of the posterior longitudinal ligament. 相似文献
4.
One of the current issues in the peer-to-peer streaming systems is to supply sufficient upload bandwidth for continuous streaming of high-quality video channels. The helpers as upload bandwidth boosters can improve the streaming capacity of system, so that the imbalance of upload bandwidth between different video channel overlays is compensated. With the deployment of helpers as an intermediate level between server and peers, building and maintaining the optimal peer-helper topology becomes a challenging task since the one-directional nature of video streaming from the helpers to users makes the well-known reciprocity-based algorithms useless. Because of selfish behavior of peers and lack of a central authority among them, selection of helpers requires implicit coordination. In this paper, we design a decentralized, stochastic approximation helper selection mechanism which is adaptable to supply and demand pattern of various video channels. Our regret-tracking-based solution for allowing peers to strategically exploit their shared resources is guaranteed to converge to the correlated equilibria (CE) among the helper selection strategies. Online convergence to the set of CE is achieved through the regret-tracking algorithm which tracks the equilibrium in the presence of stochastic dynamics of helpers’ bandwidth. The resulting CE can help to select proper cooperation policies. Simulation results demonstrate that our algorithm achieves good convergence, load distribution on helpers and sustainable streaming rates for peers. 相似文献
5.
An N*N self-routing planar network suitable for fabricating optical space switches on lithium niobate substrate is presented. The network has O(N/sup 2/) cross points, good modularity and expandability. It also has no waveguide crossovers and no differential attenuation between any of the input and output pairs. A self-routing control can be applied to this network, which is indispensable for ATM switching systems.<> 相似文献
6.
A quick and simple method for the identification of meat species and meat products by PCR assay 总被引:5,自引:0,他引:5
Matsunaga T Chikuni K Tanabe R Muroya S Shibata K Yamada J Shinmura Y 《Meat science》1999,51(2):143-148
The polymerase chain reaction (PCR) was applied to identify six meats (cattle, pig, chicken, sheep, goat and horse) as raw materials for products. By mixing seven primers in appropriate ratios, species-specific DNA fragments could be identified by only one multiplex PCR. A forward primer was designed on a conserved DNA sequence in the mitochondrial cytochrome b gene, and reverse primers on species-specific DNA sequences for each species. PCR primers were designed to give different length fragments from the six meats. The products showed species-specific DNA fragments of 157, 227, 274, 331, 398 and 439 bp from goat, chicken, cattle, sheep, pig and horse meats, respectively. Identification is possible by electrophoresis of PCR products. Cattle, pig, chicken, sheep and goat fragments were amplified from cooked meat heated at 100 or 120°C for 30 min, but horse DNA fragments could not be detected from the 120°C sample. Detection limits of the DNA samples were 0.25 ng for all meats. 相似文献
7.
The authors present a method by which to construct a fast N*N self-routing space switch network with identical 2*2 switch elements. This network is nonblocking and employs O(N log/sup 3/ N) switch elements; each element uses just two bits of the output port address for switching control.<> 相似文献
8.
Sherif A. El‐Safty Adel A. Ismail Hideyuki Matsunaga Takaaki Hanaoka Fujio Mizukami 《Advanced functional materials》2008,18(10):1485-1500
General design of optical chemical nanosensors is needed to develop efficient sensing systems with high flexibility, and low capital cost for control recognition of toxic analytes. Here, we designed optical chemical nanosensors for simple, high‐speed detection of multiple toxic metal ions. The systematic design of the nanosensors was based on densely patterned chromophores with intrinsic mobility, namely, “building‐blocks” onto three‐dimensional (3D) nanoscale structures. The ability to precisely modify the nanoscale pore surfaces by using a broad range of chromophores that have different molecular sizes and characteristics enables detection of multiple toxic ions. A key feature of this building‐blocks design strategy is that the surface functionality and good adsorption characteristics of the fabricated nanosensor arrays enabled the development of “pool‐on‐surface” sensing systems in which high flux of the metal analytes across the probe molecules was achieved without significant kinetic hindrance. Such a sensing design enabled sensitive recognition of metal ions up to sub‐picomolar detection limits (~10?11 mol dm?3), for first time, with rapid response time within few seconds. Moreover, because these sensing pools exhibited long‐term stability, reversibility and selectivity in detecting most pollutant cations, for example, Cr(VI), Pb(II), Co(II), and Pd(II) ions, they are practical and inexpensive. The key result in our study is that the pool‐on‐surface design for optical nanosensors exhibited significant ion‐selective ability of these target ions from environmental samples and waste disposals. 相似文献
9.
Wakejima A. Matsunaga K. Okamoto Y. Ando Y. Nakayama T. Miyamoto H. 《Electronics letters》2005,41(25):1371-1372
A single-ended amplifier using small packaged GaN-FETs exhibits a record 2.14 GHz W-CDMA output power. The amplifier, composed of paralleled 48 mm gate periphery FET die, delivers a peak saturated output power of 371 W with a linear gain of 11.2 dB at a drain voltage of 45 V under 2.14 GHz 3GPP W-CDMA signal input. The output power density (output power/package size) of 1.1 W/mm/sup 2/ is twice as high as that of the existing over 300 W GaAs-FET amplifiers. A low 5 MHz offset ACLR of -36 dBc with a drain efficiency of 24% is also obtained at 8 dB power back off from the saturated output power. 相似文献
10.
Keizo Uematsu Jin-Young Kim Masayori Miyashita Nozomu Uchida Katsuichi Saito 《Journal of the American Ceramic Society》1990,73(8):2555-2557
The internal structure of spray-dried alumina granules was characterized by optical microscopy by immersing them in a liquid having a refractive index close to that of alumina. This method provides a unique technique for the detailed analysis of the internal structure of spray-dried granules. 相似文献