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        검색결과 223

        104.
        2007.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        From the HCN observations of dense molecular cloud L694-2, Lee et al.(2007) determined internal distributions of density and velocity for the cloud. The density profile collaborates roughly with the Bonnor- Ebert gas sphere, but the velocity field departs significantly from the result of numerical simulations that are started from the BE sphere. Taking L694-2 as an example of collapsing clouds, we have performed a series of collapse simulations and determined initial configurations for the cloud in such a way that the resulting density and velocity profiles both match with the empirically deduced ones. Among many trial configurations the cloud which is initially uniform in density and bound by an expanding envelop depicts most closely the empirically obtained profiles of both density and velocity.
        3,000원
        118.
        2005.12 구독 인증기관 무료, 개인회원 유료
        The present study was conducted to investigate gelatinolytic activities in HAM and to determine whether there are any changes in gelatinolytic activity profiles when the cells are cultured in hepatogenic medium. Placenta was obtained during caesarean section of the volunteers, with informed consent. HAM were isolated from amniotic membrane using collagenase type A HAM were cultured in hepatogenic medium for 3 weeks and the conditioned media were obtained at day 7, 14 and 21. The zymographic pattern of gelatinolytic activity of the HAM did not undergo a change during passages. When the HAM were cultured in a fibronectin-coated dishes in a hepatogenic medium, there was no significant difference of the gelatinase pattern between before and after culture. However, when bFGF was added to the culture, a dramatic increase of 62kDa and 59kDa gelatinases was observed. Interestingly, when ITS instead of FN was present, HAM-conditioned medium also showed a similar increase of both gelatinases. Immunoblotting analysis demonstrated that both 62kDa and 59kDa gelatinases were the active form of MMP-2 resulting from the turnover of MMP-2 proform. Futher study will be necessary to determine the relationship between bFGF and active MMP-2 during hepatogenesis of HAM.
        4,000원
        119.
        2005.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Nanoscale Al powder with thin layer of alumina was produced by Wire Electric Explosion (WEE) process. Spark-Plasma Sintering (SPS) was performed for the produced powder to confirm the effectiveness of SPS like so-called 'surface-cleaning effect' and so on. Crystallite size and alumina content of produced powder varied with the ratio of input energy to sublimation energy of Al wire (): Increase in () resulted in the decrease of crystallite size and the increase of alumina content. Shrinkage curve during SPS process showed that the oxide surface layer could not be destroyed near the melting point of Al. It implied that there was not enough or no spark-plasma effect during SPS for Al/Alumina powder.
        4,000원
        120.
        2005.09 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was the analysis of sperm ability in Specific Pathogen Free (SPE) miniature pig for production of bio-organ. The collected semen was diluted with extender and stored at 17℃ for up to 7 days. The semen samples were evaluated at 0, 1, 3, 5, and 7 days of storage for analysis of sperm ability. Sperm ability was evaluated by examining viability, progressive motility, sperm abnormality and intensity of the sperm membrane. Also, the semen was processed according to the convenient freezing method, and frozen-thawed sperm was evaluated by examining viability, capacitation and acrosome reaction using chlortetracycline (CTC) staining. Motility of spermatozoa of SPF miniature pig was significantly (P<0.05) lower on 3 days or later compared to the Duroc, Yorkshire and Landrace in domestic boar. The percentage of abnormal spermatozoa of Landrace were significantly (P<0.05) higher than in SPF miniature pig, Duroc and Yorkshire that had a similar percentage on 5 or 7 days of sperm storage. The percentage of spermatozoa with coiled tail decreased during the storage period but there were no significant difference. On the other hand, viability of frozen-thawed spermatozoa had a significantly (P<0.05) lower in SPF miniature pig than in other domestic boars. CTC patterns had no significant difference, but SPF miniature pig had higher percentage of capacitated spermatozoa and lower percentage of acrosome-reacted it than domestic boars. Therefore, this study suggest that it is necessary to develop the suitable extender and freezing methods methods for the high viable rate and fertilizing ability in vitro.
        4,000원