검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 679

        481.
        2007.06 구독 인증기관 무료, 개인회원 유료
        This study was designed to evaluate effects of BSA, PVA, gonadotropins and follicle shell during IVM of porcine oocytes and subsequent development to the blastocyst stage after IVF. Cumulus oocyte complexes (COCs) were cultured in TCM-199 media containing 4 mg/ml BSA and 1 mg/ml PVA during IVM for 44 hr. To compare the effect of gonadotropins on oocyte maturation, COCs were cultured with FSH+LH, FSH, LH and FSH-LH-free media during IVM, respectively. Also, different number of follicle shells (0, 2, 4 and 6) was used to examine whether the presence of follicle shell in culture medium affects oocyte maturation. The percentages of fertilization and blastocyst formation, respectively, were higher in the medium containing the PVA (49.0 and 17.9%) than those containing the BSA (40.0 and 12.2%). Significantly higher rates of MII oocytes were in the presence of FSH+LH and FSH (88.6 and 85.1%) compared to other treatments (64.0 and 53.4% at LH and FSH-LH-free media). Co-culture with inverted follicle shells in 2 ml maturation medium enhanced the developmental competence of porcine oocytes. In conclusion, PVA could be used as a macromolecules instead of BSA, and FSH and follicle shell played important roles in maturation of porcine oocytes.
        4,000원
        482.
        2006.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Carbon/Carbon composite was been manufactured by the technology of warmer-molding process of clutter chopped carbon fiber, using phenolic resin as an adhesive. The degree of graphitization, the microstructure and the friction properties were studied. The results show that the clutter chopped carbon fiber fully scatter in the Carbon/Carbon composite and the degree of graphitization of phenolic resin can reach up to 86.2%, this matrix carbon can form the continuous and stable graphitic thin film on the friction surface during braking process so that the composite has fine friction properties and low wear rate.
        3,000원
        483.
        2006.09 구독 인증기관·개인회원 무료
        Study about the feasibility and effect of high-energy ball milling on a specific Mg alloy under protection medium of alcohol was presented via comparing with conventional vacuum milling. More fine particles with wider powder size distribution but more irregular shape were shown of the powder milled under alcohol. No obvious oxide was revealed from the two kinds of Mg alloy powders with limited milling time. And since slip induced in a preferential direction, the (002) texture was formed in the Mg alloy powders at the initial stage of alcohol milling. More O and Fe contaminants were introduced into the powders milled under alcohol according to the EDS analysis.
        484.
        2006.09 구독 인증기관·개인회원 무료
        In this paper, the fundamental attributes, phase composition of three pre-alloyed powders for diamond tools by water atomization were investigated. The density, hardness, bend strength and bending modulus of their hot pressing samples were examined. The results showed that the three pre-alloyed powders have excellent low temperature sintering characteristics. The physical and mechanical properties of the samples were found to be nearly the same as those of fine cobalt powders.
        485.
        2006.09 구독 인증기관·개인회원 무료
        The processes of P/M affect the properties of sintered gears. The different techniques of P/M lead to the different properties of sintered gears. This paper summarizes new progress in powder metallurgy for sintered gears. These progresses include warm compaction, high velocity compaction, sinter hardening, high temperature sintering, infiltration, CNC powder press and surface densification etc.
        487.
        2006.09 구독 인증기관·개인회원 무료
        The composite used in this paper was prepared by hot-pressing ball-milled Mg alloy powders, in which NiTi shape memory alloy fibers in a row were sandwiched. The microstructure and property were examined. It is shown that the composite consisted of a homogenous matrix with uniformly distributed NiTi shape memory alloy fibers, recrystallization took place in the Mg alloy matrix which was subjected to plastic deformation an adequate bonding formed between the matrix and fibers; the density and tensile strength of the composite increased after the hot-forging; the hot-forging process is capable of improving properties of the composite.
        488.
        2006.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        6,300원
        489.
        2006.04 구독 인증기관·개인회원 무료
        This paper introduces a special spheroidizing technology at ultra-high temperature. The conventional cast tungsten carbide (YZ) is melted at high temperature, rapidly cooled and spheroidized on a new ultra-high temperature spheroidizing equipment to prepare various grades WSC powders.
        490.
        2006.04 구독 인증기관·개인회원 무료
        The influence of Hi-flux powders characteristics on the performance of magnetic powder cores was studied. It was found that different cooling rate and nozzle configuration could change the shape and microstructure of powders. Smooth surface and spherical shape of powders were beneficial to improve DC bias performance and reduce core losses of magnetic powder core.
        491.
        2006.04 구독 인증기관·개인회원 무료
        This paper described the preparation method for composing high-grade synthetic diamond by water atomizing using FeNi30 powder catalyst. The objective of this article is about powder making process using super high water atomizing in the atmosphere of inert gas, and then corroded the powder with a corrosion inhibitor. Finally, FeNi30 catalyst powder with lower oxygen content and good sphericity is produced. The experiment of making diamonds by using cubic press and the performance of the diamonds are also discussed.
        494.
        2006.04 구독 인증기관·개인회원 무료
        The primary aim pursued by the preparation of separation membrane is the preparation of the membrane thin as well as with no defect. The field-flow fractionation deposition is a new molding technology which can overcome the traditional disadvantages such as multi-preparation to the preparation of great area of separation membrane with no defect. Therefor the mainly ingredients which influence the appearance and performance of titanium membrane layer are investigated by scanning electricity mirror (SEM) as well as porous material testing instrument: powder performance prepared and confected; selection of supporting body; sintering system such as temperature and time. It is shown that the membrane thickness can be controlled at or so; the filtration precision mainly rests with powder performance and selection of supporting body and little sintering system
        495.
        2006.04 구독 인증기관·개인회원 무료
        The mechanical properties of ferrous powder metallurgy (P/M) materials are directly related to their microstructure. Ferrous P/M materials with sufficient hardenability will develop microstructures containing significant percentages of martensite in the as-sintered condition. Recently, sinter-hardening has developed into a highly cost effective production method through hardened P/M parts without the need for additional heat-treatments. This paper reviews the advances of sinter-hardening as well as some key processing parameters such as sintering temperature, cooling rate, tempering required to produce high quality sinter-hardened components. Specific topics including effect of alloying elements, alloying methods, and the Characterization and observation of microstructure are discussed.
        496.
        2006.04 구독 인증기관·개인회원 무료
        A new process of pulsed electric current sintering was developed. It combines compaction with activated sintering effectively and can manufacture bulky nano-crystalline materials very quickly. A nano-structured steel is obtained with high relative density and hardness by this process. The average grain size of iron matrix is 58nm and the carbide particulate size is less than 100 nm. The densification temperature of ball-milled powders is approximately lower than that of blended powders. When the sintering temperature increases, the density of as-sintered specimen increases but the hardness of as-sintered specimen first increases and then decreases.
        498.
        2005.06 KCI 등재 SCOPUS 구독 인증기관·개인회원 무료
        The working group for an infrared telescope(IRT) toward East Asian Observatory has been set up in EAMA6. This report declares the membership of IRT working group, reviews briefly the activities of promoting the IRT, and puts forward the future plan.
        499.
        2005.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This paper reviews the progress in the VLBI (Very Long Baseline Interferometry) studies of Sgr A*, the best known supermassive black hole candidates with a dark mass concentration of 4x106 M⊙ at the center of the Milky Way. The emphasis is on the importance of the millimeter and sub-millimeter VLBI observations in the detection of Sgr A*'s intrinsic structure and search for the structural variation.
        4,000원
        500.
        2005.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present CO(3-2), CO(2-1), and 230 GHz (1.3 mm) continuum images of nearby galaxies taken with the Submillimeter Array (SMA). Our main topic is to study the relation between higher-J molecular gas (e.g., CO J=3-2, 2-1) and nuclear activities (e.g., active galactic nuclei [AGNs] and starbursts). The nearby Seyfert 2 galaxy M51 shows strong CO(3-2) emission from the circumnuclear molecular gas, with an intensity twice as strong as that of the CO(1-0) emission. Strong CO(3-2) emission enhancement suggests that the circum nuclear molecular gas in M51 is warm and dense, which may be related to the AGN activities. Molecular gas in the nearby moderate starburst galaxy NGC 6946 is distributed along the large-scale bar or spiral arms and along the minibar, and the multi-J CO line images show very similar distribution to each other. For this galaxy, there is no clear enhancement in higher-J lines as seen in M51, which may be because NGC 6946 does not have clear AGN activities. Based on the results of these two galaxies, the physical conditions of the circum nuclear molecular gas may be related to the AGN activities. We also observed the nearby edge-on starburst galaxy NGC 3628 and the starburst/Seyfert composite galaxy NGC 4945 with the CO(2-1) line and 230 GHz (1.3 mm) continuum emission. These information will give us some hints for understanding the relation between nuclear activities and circum nuclear molecular gas and dust.
        3,000원