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排序方式: 共有1346条查询结果,搜索用时 15 毫秒
71.
Se-Jung Jang Seung-Suk Baek Jeong-Yeol Kim 《Journal of Adhesion Science and Technology》2013,27(19):1990-2000
Transparent acrylic pressure sensitive adhesives (PSAs) comprised semi-interpenetrated structured polymer networks were prepared with different co-monomer compositions. Emphasis was placed on the effect of functional groups in the co-monomer including morpholine and tetrahydrofurane moieties in the typical acrylic PSA formulation. The synthesized acrylic PSA syrups were characterized and the optical properties of the acrylic PSA film were also examined by ultraviolet–visible spectroscopy, haze meter, and prism coupler. Acrylic PSAs exhibit high transparency in the visible wavelength region. Adhesion performance was measured by the peel strength, cohesion strength, and probe tack tests. With increasing 4-acryloyl morpholine monomer concentration in the acrylic PSAs, the peel strength, cohesion strength, and probe tack increased. 相似文献
72.
T. J. Shin H. K. Park S. W. Lee B. Lee W. Oh J.‐S. Kim S. Baek Y.‐T. Hwang H.‐C. Kim M. Ree 《Polymer Engineering and Science》2003,43(6):1232-1240
A series of aromatic polyimides composed of well‐defined conjugation units were synthesized form 5,5′‐bis(4‐aminophenyl)‐2,2′‐bifuryl (PFDA) and 2,2′‐bis(furyl) benzidine (FurylBZ) with various dianhydrides. The synthesized polyimides emit blue to green light with a quantum yield of 7.3–14.9%, depending on the polymer backbone. In particular, PFDA‐based polymers exhibit extremely narrow photo‐luminescence. The structure, thermal stability, refractive index and dielectric properties of the polymer films were also determined. 相似文献
73.
Mi-Hwa Baek Won-Chae Jung Ji-Won Yoon Ji-Sook Hong Young-Seak Lee Jeong-Kwon Suh 《Journal of Industrial and Engineering Chemistry》2013,19(2):469-477
The influences of heat-treatment temperature and activation time on the properties of TiO2 supported on spherical activated carbon (TiO2/SAC) were investigated. Nano-sized TiO2 was dispersed on the spherical activated carbon with the size of 10–30 nm. Some anatase phase of TiO2 was transformed to rutile phase of TiO2 with an increase of heat-treatment temperature. All of the TiO2/SAC photocatalysts had microporous structure, with the mesopore volume increasing over an activation time of 6 h. The TiO2/SAC photocatalysts obtained at activation times of 6 h and 9 h were observed synergistic effects between adsorption and photocatalysis in the removal of humic acid. 相似文献
74.
Ilhyun Baek 《Korean Journal of Chemical Engineering》2000,17(5):553-558
Preparation of semi-activated carbon fibers (SACFs) using a precursor consisting of coal tar pitch and phenolic resin coated
on glass fiber was investigated. Stabilization of the fiber structure by crosslinking both the phenolic resin and coal tar
pitch was essential to achieving high surface areas during high temperature activation. The phenolic resin was cured by using
aqueous catalyst (hydrochloric acid/formaldehyde) followed by oxidative stabilization of the pitch. A surface area of 1,206
m2/g based on the precursor was obtained through activation using carbon dioxide/steam at 880 ‡C. The pore size distribution
was shown to be vary narrow using the Horvath-Kawazoe (HK) method. 相似文献
75.
Seiji Shinohara Jong-Gab Baek Tetsuhiko Isobe Mamoru Senna 《Journal of the American Ceramic Society》2000,83(12):3208-3210
Phase-pure perovskite Pb(Zn x Mg1– x )1/3 Nb2/3 O3 solid solution (PZ x M1– x N) is obtained for x ≦ 0.7 by heating a milled stoichiometric mixture of PbO, Mg(OH)2 , Nb2 O5 , and 2ZnCO3 ·3Zn(OH)2 ·H2 O at 1100°C for 1 h. Percent perovskite ( f P ) with respect to total crystalline phase decreases with increasing temperature of subsequent heating then increases to 900°C for the mixtures where x ≦ 0.8 and milled for 3 h. For mixtures with x = 0.9 and x = 1, f P decreases monotonically. Curie temperature increases almost linearly with increasing x up to x = 0.7. The maximum dielectric constant at 1 kHz is 2×104 and 1.7×104 for the mixture with x = 0.4 and x = 0.7, respectively. The stabilization mechanism of strained perovskite is discussed. 相似文献
76.
Baek Hyun Kim Jong Hoon Park Byungkyu Kim Do-Kyun Kwon 《Metals and Materials International》2012,18(6):1067-1072
Liquid phase sintering of lead zirconate titanate (abbreviated as PZT) ceramics with a 0.78 PbO-0.22 CuO (10:1 in weight ratio) flux was investigated. A small amount sintering flux consisting of a stoichiometrically mixed oxide of PbO-CuO with a eutectic composition successfully accelerated densification of the PZT ceramics far below the conventional sintering temperature. With the 3 wt% flux additions, full densifications of the PZT ceramics were achieved at temperatures as low as 825 °C. The results obtained in the crystal structure, microstructure, and electrical property analyses suggest that the Cu2+ impurity ion substitutes as an acceptor center for the perovskite B-site without forming isolated secondary phases. Defect associates of the Cu2+ impurities and charge compensating oxygen vacancies appear to affect dielectric and piezoelectric properties of the sintered PZT samples in both positive and negative ways by forming defect dipoles. When the Cu2+ content is small, slightly improved dielectric and piezoelectric performances were achieved, though ferroelectric relaxation was obviously developed at the higher Cu2+ contents. For the PZT samples sintered at 825 °C with 3 wt% flux addition, relative dielectric permittivity was 2200 and dielectric loss was less than 2%. Remnant polarization, coercive fields, and piezoelectric coefficient (d33) were 32 μC/cm2, 8.9 kV/cm and 373 pC/N, respectively. 相似文献
77.
The effect of adding 0.04% additional boron to 6.5% V-5% W high speed steel was investigated. The microstructure characterization, phase identification, and carbide identification of the materials were performed using SEM/EDS and XRD. The cell size and carbide volume fraction were examined using image analysis software. The boron distribution was observed by PTA Boron Tracking. The addition of 0.04% more boron to a HSS alloy exerted a cell refining effect on the sample. The cell refinement of dendritic structures in the alloy containing boron may be attributed to the constitutional supercooling effect associated with the fairly small distribution coefficient for boron in iron. The addition of boron increases the bending strength of the material by more than 10%, as well as increasing its hardness. 相似文献
78.
Myoung-Eun Han Young-Suk Lee Sun-Yong Baek Bong-Seon Kim Jae-Bong Kim Sae-Ock Oh 《International journal of molecular sciences》2009,10(7):3033-3043
Gastric cancer is the second most common cause of cancer deaths worldwide. The underlying molecular mechanisms of its carcinogenesis are relatively poorly characterized. Hedgehog (Hh) signaling, which is critical for development of various organs including the gastrointestinal tract, has been associated with gastric cancer. The present study was undertaken to reveal the underlying mechanism by which Hh signaling controls gastric cancer cell proliferation. Treatment of gastric cancer cells with cyclopamine, a specific inhibitor of Hh signaling pathway, reduced proliferation and induced apoptosis of gastric cancer cells. Cyclopamine treatment induced cytochrome c release from mitochondria and cleavage of caspase 9. Moreover, Bcl-2 expression was significantly reduced by cyclopamine treatment. These results suggest that Hh signaling regulates the survival of gastric cancer cells by regulating the expression of Bcl-2. 相似文献
79.
Dae Kyun Baek Tae Jo Ko Hee Sool Kim 《Journal of Materials Processing Technology》2000,100(1-3):266-272
A monitoring system that can detect tool breakage and chipping in real time was developed using a digital signal processor (DSP) board in a face milling operation. An autoregressive (AR) model and a band energy method were used to extract the features of tool states from cutting force signals. Then, two artificial neural networks, which have a parallel processing capability, were embedded on the DSP board to discriminate different malfunction states from features obtained by each of the two methods of signal processing. In experiments, we found that feature parameters extracted by AR modeling were more accurate indicators of malfunctions in the process than those from the band energy method, although the computing speed is slower. By using the selected features, we were able to monitor malfunctions in real time. 相似文献
80.
Su-Min Baek Seoung-Woo Lee Tae-Un Kim Seong-Kyoon Choi Sungho Yun Won-Jae Lee Se-Hyeon Han Il-Hwa Hong Sang-Joon Park Tae-Hwan Kim Kyu-Shik Jeong Jin-Kyu Park 《International journal of molecular sciences》2021,22(5)
Senescence marker protein 30 (SMP30) is a cell survival factor playing an important role in vitamin C synthesis and antiapoptosis. Moreover, its cytoprotective role suggests a possibility to be related to cancer cell survival. Mammary carcinoma is a common cancer in both humans and animals. Because of its histopathological diversity, especially in the early stage, histopathological diagnosis may be complicated; therefore, a diagnostic marker is helpful for confirmation. The present study analyzed the expression pattern of SMP30 in mammary carcinoma in humans, dogs, and cats. Immunohistochemistry, immunofluorescence, and western blot analysis were used to investigate SMP30 expression patterns. The expression was specifically observed in neoplastic glandular epithelial cells. The expression increased with the malignancy of glandular epithelial cells with a highly proliferative status. However, SMP30 expression was low in normal mammary gland tissues or well-differentiated adenoma tissues. The patterns were consistently reproduced in canine primary mammary carcinoma cells and MCF-7 and MDA-MB-231 human carcinoma cell lines. This study provides useful information to understand SMP30 expression in various stages of mammary carcinoma and to suggest its utility as a pan-species diagnostic marker, thereby helping to establish strategies for diagnosing mammary carcinoma in several species. 相似文献