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        검색결과 21

        1.
        2021.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, graphene was rapidly grown by chemical vapor deposition using a liquid cell for supplying methanol as a carbon source of graphene. To realize the rapid growth, methanol which is carbon-contained organic solvent was used instead of methane gas, a widely used carbon source for graphene growth. The graphene grown with the growth time as a variable was transferred to a SiO2/ Si substrate with an oxide thickness of 300 nm to confirm whether it was grown with full coverage with an optical microscope. The results confirmed a full coverage in 0.5 min of growth. The Raman spectra also confirmed the G-peak position at 1585.0 cm−1 and an intensity ratio of 2D/G at 2.3 or higher. Concerning electrical transport characteristics, at an induced carrier density of 1 × 1012 cm−2, the hole (μh) and electron (μe) mobilities were 1524 cm2 V−1 s−1 and 1528 cm2 V−1 s−1, respectively. Thus, our study confirmed that high-quality, large-area graphene can be grown within 0.5 min.
        4,000원
        2.
        2011.09 구독 인증기관 무료, 개인회원 유료
        This study was undertaken to evaluate the relationship between in vitro maturation and plasminogen activators (PAs) activity on porcine cumulus-oocytes complexes (COCs) exposed to oxidative stress. When COCs were cultured in maturation medium with hydrogen peroxide (H2O2), the proportion of the germinal vesicle breakdown (GVBD) and oocytes maturation were decreased with addition of H2O2, and were significantly (p<0.05) lower in medium with 0.1 mM H2O2 than control group. Also, the rate of degenerated oocytes was increased in as H2O2 concentration increased. When COCs were cultured for 48 h, three plasminogen-dependent lytic bands were observed: tissue-type PA (tPA); urokinase-type PA (uPA); and tPA-PA inhibitor (tPA-PAI). PA activity was quantified using SDS-PAGE and zymography. When H2O2 concentration was increased, tPA and tPA-PAI activities also increased in porcine oocytes cultured for 48 h, but not uPA. In other experiment, embryos were divided into three groups and cultured in (1) control medium, (2) control medium with 1.0 mM H2O2 and (3) control medium with 1.0 mM H2O2 along with catalase in concentrations of 0.01, 0.1, and 1.0 mg/ml, respectively. H2O2 decreased the rate of GVBD and maturation in porcine COCs but catalase revealed protective activity against oxidative stress caused by H2O2. In this experiment, tPA and tPA-PAI activities were higher in media with 1.0 mM H2O2 alone. Increasing concentration of catalase decreased tPA and tPA-PAI activities in porcine oocytes. These results indicate that the exposure of porcine follicular oocytes to ROS inhibits oocytes maturation to metaphase-II stage and increase the oocytes degeneration. Also, we speculated that increased ROS level may trigger tPA and tPA-PAI activities in porcine oocytes matured in vitro.
        4,000원
        3.
        2010.05 구독 인증기관·개인회원 무료
        The bumblebee, Bombus ignitus (Hymenoptera: Apidae), is a valuable natural resource that is one of the most notably utilized for greenhouse pollination in Korea. In order to understand the nature of genetic relationships, gene flow, and population structure of the species we sequenced a partial COI gene of mitochondrial DNA (mtDNA) corresponding to “animal barcode” region and the complete internal transcribed spacer 2 (ITS2) of the nuclear ribosomal DNA (nrDNA) collected from Korean localities. Although the 658-bp long mtDNA sequence provided only six haplotypes with the maximum sequence divergence of 0.61% (4 bp), the ITS sequences provided 84 sequence types with the maximum sequence divergence of 1.02% (21 sites), confirming better applicability of the ITS sequences to the study of intraspecific variation. The complete ITS2 sequences of B. ignitus were shown to be longest among known insects, ranging in size from 2,034 bp ~ 2,052 bp, harboring two duplicated repeats. Overall, a very high per generation migration ratio, a very low level of genetic fixation, and no discernable hierarchical population/ population group were noted to exist among populations of B. ignitus on the basis of both molecules, thus suggesting that the B. ignitus populations on the Korean peninsula are panmictic, which is consistent with our understanding of the dispersal capability of the species
        4.
        2009.05 구독 인증기관·개인회원 무료
        Root knot nematode species, such as Meloidogyne hapla, M. incognita, M. arenaria and M. javanica are economically most notorious nematode pests, causing serious damage to the various crops throughout world. In this study, DNA sequence analyses of the D1-D3 expansion segments of the 28S gene in the ribosomal DNA were conducted to characterize genetic variation of the four Meloidogyne species obtained from Korea and United States. PCR-RFLP (Polymerase Chain Reaction-Restriction Fragment Length Polymorphism), SCAR (Sequence Characterized Amplified Region) marker and RAPD (Random Amplification of Polymorphic DNA) also were used to develop the methods for exact and rapid species identification. In the sequence analysis of the D1-D3 expansion segments, only a few nucleotide sequence variation were detected among M. incognita, M. arenaria, and M. javanica, except for M. hapla. The PCR-RFLP analysis that involves amplification of the mitochondrial COII and lrRNA region yielded one distinct amplicon for M. hapla at 500 bp, enabling us to distinguish M. hapla from M. incognita, M. arenaria, M. javanica reproduced by obligate mitotic parthenogenesis. SCAR markers successfully identified the four root knot nematode species tested. We are under development of RAPD primers specific to the three root knot nematodes found in Korea.
        16.
        2007.09 KCI 등재 서비스 종료(열람 제한)
        “Shinmichal1”, a waxy red winter wheat (Triticum aestivum L.) cultivar was developed by the National Institute of Crop Science, RDA. It was derived from the cross “Alchan”/“Chal2”during 1997. “Alchan” is a soft red winter wheat with high yield and good noodle quality. “Chal2” is a waxy wheat line crossed by “Kanto107” (Wx-A1b and Wx-B1b) and “BaiHuo” (Wx-D1b). “Shinmichal1” was evaluated as “Suwon306” in Advanced Yield Trial Test in 2002. It was tested in the regional yield trial test between 2003 and 2006. “Shinmichal1” is an awned, semi dwarf and soft red winter wheat, similar to “Uri” (check cultivar). The Heading and maturing date of “Shinmichal1” were similar to “Uri”. Culm and spike length of “Shinmichal1“ were 79 cm and 7.8 cm. “Shinmichal1“ had greater test weight (802 g) and lower 1,000-grain weight (31.8 g) than “Uri” (782 g and 35.2 g, respectively). It has resistance to winter hardiness, wet-soil tolerance, lodging tolerance and moderate post-harvest sprouting damage. “Shinmichal1” had higher flour yield (66.2%), ash (0.73%), protein (10.9%) and SDS sedimentation volume (40.7 ml) than “Uri” (64.7%, 0.53%, 9.3%, and 32.5 ml, respectively) and similar flour color to “Uri”. “Shinmichal1” had higher dough extensibility and lower dough strength than “Uri”. It is 5.2% of amylose content and had typical waxy starch pasting properties. Average yield of “Shnmichal1” in the regional adaptation yield trial was 5.24 MT ha-1 in upland and 5.58 MT ha-1 in paddy field, which was 3% and 8% lower than those of “Uri” (5.39 MT ha-1 and 6.09 MT ha-1, respectively). “Shinmichal1” would be suitable for the area above the daily minimum temperature of -10℃ in January in Korean peninsula.
        20.
        2004.08 KCI 등재 서비스 종료(열람 제한)
        In this study, we present different physiological responses to cold acclimation between the freezing tolerant barley landrace, Jeonnamjaerae, and the freezing sensitive line, PI283398, chosen by the previous field test. We tried to identify some key facto
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