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        검색결과 5

        1.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We present observational results characterizing molecular out ows from very low-mass objects in ρ Ophiuchi and Taurus. Our results provide us with important implications that clarify the formation process of very low-mass objects.
        3,000원
        3.
        2001.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        CTA ester bonds in TG molecules were not attacked by pancreatic lipase and lipases produced by microbes such as Candida cylindracea, Chromobacterium viscosum, Geotricum candidium, Pseudomonas fluorescens, Rhizophus delemar, R. arrhizus and Mucor miehei. An aliquot of total TG of all the seed oils and each TG fraction of the oils collected from HPLC runs were deuterated prior to partial hydrolysis with Grignard reagent, because CTA molecule was destroyed with treatment of Grignard reagent. Deuterated TG (dTG) was hydrolyzed partially to a mixture of deuterated diacylglycerols (dDG), which were subsequently reacted with (S)-(+)-1-(1-naphthyl)ethyl isocyanate to derivatize into dDG-NEUs. Purified dDG-NEUs were resolved into 1, 3-, 1, 2- and 2, 3-dDG-NEU on silica columns in tandem of HPLC using a solvent of 0.4% propan-1-o1 (containing 2% water)-hexane. An aliquot of each dDG-NEU fraction was hydrolyzed and (fatty acid-PFB ester). These derivatives showed a diagnostic carboxylate ion, (M-1)-, as parent peak and a minor peak at m/z 196 (PFB-CH3)- on NICI mass spectra. In the mass spectra of the fatty acid-PFB esters of dTGs derived from the seed oils of T. kilirowii and M. charantia, peaks at m/z 285, 287, 289 and 317 were observed, which corresponded to (M-1)- of deuterized oleic acid (d2-C18:0), linoleic acid (d4-C18:0), punicic acid (d6-C18:0) and eicosamonoenoic acid (d2-C20:0), respectively. Fatty acid compositions of deuterized total TG of each oil measured by relative intensities of (M-1)- ion peaks were similar with those of intact TG of the oils by GLC. The composition of fatty acid-PFB esters of total dTG derived from the seed oils of T. kilirowii are as follows; C16:0, 4.6 mole % (4.8 mole %, intact TG by GLC), C18:0, 3.0 mole % (3.1 mole %), d2C18:0, 11.9 mole % (12.5 mole %, sum of C18:1Ω9 and C18:1Ω7), d4-C18:0, 39.3 mole % (38.9 mole %, sum of C18:2Ω6 and its isomer), d6-C18:0, 41.1 mole % (40.5 mole %, sum of C18:3 9c,11t,13c, C18:3 9c,11t,13r and C18:3 9t,11t,13c), d2-C20:0, 0.1 mole % (0.2 mole % of C20:1Ω9). In total dTG derived from the seed oils of M. charantia, the fatty acid components are C16:0, 1.5 mole % (1.8 mole %, intact TG by GLC), C18:0, 12.0 mole % (12.3 mole %), d2-C18:0, 16.9 mole % (17.4 mole %, sum of C18:1Ω9), d4-C18:0, 11.0 mole % (10.6 mole %, sum of C18:2Ω6), d6-C18:0, 58.6 mole % (57.5 mole %, sum of C18:3 9c,11t,13t and C18:3 9c,11t,13c). In the case of Aleurites fordii, C16:0; 2.2 mole % (2.4 mole %, intact TG by GLC), C18:0; 1.7 mole % (1.7 mole %), d2-C18:0; 5.5 mole % (5.4 mole %, sum of C18:1Ω9), d4-C18:0 ; 8.3 mole % (8.5 mole %, sum of C18:2Ω6), d6-C18:0; 82.0 mole % (81.2 mole %, sum of C18:3 9c,11t,13t and C18:3 9c,11t,13c). In the stereospecific analysis of fatty acid distribution in the TG species of the seed oils of T. kilirowii, C18:3 9c,11t,13r and C18:2Ω6 were mainly located at sn-2 and sn-3 position, while saturated acids were usually present at sn-1 position. And the major molecular species of (C18:2Ω6)(C18:3 9c,11t,13c)2 and (C18:1Ω9)(C18:2Ω6)(C18:3 9c,11t,13c) were predominantly composed of the stereoisomer of sn-1-C18:2Ω6, <..
        5,400원
        4.
        1994.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We have reviewed three different techniques to estimate molecular cloud mass, and discussed the uncertainties involved. We found that determination of the most important parameter, the 13CO 13CO abundance, is not very sensitive to the real LTE conditions, and that any possible error in deriving LTE column density may not introduce an error in the total gas column density, as far as the visual extinction is established for the object cloud. The virial technique always endows the largest mass estimate as there are several uncertainties, even if the cloud is in virial equilibrium. The strong indicator of the cloud perturbation is the centroid velocity dispersion. The mass using CO luminosity is based on the empirical law, but weakly dependent on the virial assumption, thus it still gives a larger mass estimate. The mass discrepancy is likely to be inevitable, and a factor of two or three difference between mass estimates could easily be attributed to the uncertainties mentioned above. The LTE mass estimate may be the most reliable one if we use the relation visual extinction and 13CO 13CO column density of the object cloud, and the intercept is included.
        4,600원
        5.
        1994.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We present two codes which estimates virial mass and LTE mass using IMFORT interface within IRAF (Image Reduction and Analysis Facility). It is discussed that threshold value (temperature or CO integrated intensity), which defines a reasonable cloud boundary and size, is the most important parameter determining accurate results. Several virial masses are to be obtained using the vir task, as well as three velocity dispersions including the centroid velocity dispersion, a turbulence indicator. LTE mass is to be estimated by using task lte as well as three by-product images. The 13CO 13CO abundance and threshold temperature of 13CO 13CO and 12CO 12CO peak temperatures are the most critical parameters in LTE technique.
        4,900원