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        검색결과 4,612

        2603.
        2000.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Aloe vera 껍질에서 항우식 및 항염증제재를 개발하기 위해 항우식 및 항염증 활성이 있는 물질을 분리, 정제하였고, 활성이 우수한 ethylacetate층을 silica gel column chromatography 및 preparative thin layer chromatography를 통해 두 가지 활성물질을 정제하였다. 정제된 두 가지 물질은 UV spectrum과 FT-IR, ^1H-NMR 및 Mass spectrum 분석을 통해 aloe-emodin과 barbaloin으로 동정하였다.
        4,000원
        2604.
        2000.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        지리산국립공원 동부지역인 경남하동군 화개면에 위치하는 삼신봉(해발 1,284m) 산림 중 산불이 발생하였던 지역의 식생회복현황을 파악하기 위해 산불이 발생하였던 지역에 20개 조사구 대조지역에 12개 조사구를 설정하고 연구를 수행하였다 산불이 발생하였던 지역에 설정한 20개 조사구를 대상으로 TWINSPAN과 DCA를 분석한 결과 신갈나무군집(I) 신갈나무-쇠물푸레군집(II) 으로 분리되었고 대조지역에 설정한 조사구는 신갈나무군집(II)이었다 군집 I과 군집II에서 교목층과 아교목층의 대부분 수목이 고사상태이었고 관목층에서는 산화후 천이 초기에 나타나는 조록싸리가 우점하고 있었다 상대우점치와 유사도지수를 분석한 결과 산불이 발생하였던 신갈나무군집(I) 신갈나무-쇠물푸레군집(II) 은 대조구인 신갈나무군집(III)과 유사도지수분석에서 유사성이 높았는데 산불발생 이후 피해를 입은 신갈나무가 맹아에 의해 회복속도가 빠른 것으로 추정되었다 Shannon의 종다양도는 산불지역(군집 I,II)에서 각각 0.3259, 0.4727이었고 대조구 (군집III)는 0.1084로 나타났다.
        4,000원
        2605.
        2000.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        산소 결핍 페라이트 (oxygen deficient ferrites, ODF) MeFe2O4-δ는 약 300˚C의 낮은 온도에서 CO2를 C와 O2로 분해한다. 본 연구에서는 (Nix, Zn1-xFe24 초미세 페라이트 분말을 수열합성법으로 제조하여 CO2 분해특성을 살펴보았다. 제조된 페라이트는 XRD 분석 결과, 페라이트의 전형적인 스피넬 구조를 보여주고 있으며, ICP-AES, EDS 정량분석에 의하여 초기 혼합 조성비와 거의 동일한 조성비로 합성되었음을 알 수 있었다. 제조된 (Ni, Zn)-ferrites 분말의 BET 비표면적은 약 110mg2/g 이상의 큰 값으로 나타났으며, 입자크기는 약 5~10nm로 매우 작았다. 산소결핍 페라이트 (Nix, Zn1-x)Fe2O4-δ</TEX>의 CO2 분해 효율은 조성에 따라 큰 차이를 보이지 않았으며 3원계 (Ni, Zn)-ferrite가 Ni-ferrite보다 더 높았다.
        3,000원
        2606.
        2000.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Techniques for manipulation of spermatozoa and oocytes have been widely used for in vitro production(IVP) of Hanwoo. This study was conducted to examine the effects of theophylline and heparin on frozen-thawed Hanwoo sperm for enhancing the efficiency of IVP technique. Oocytes were inseminated with forzen bull semen treated with either theophylline or heparin for examining the effect of each substance on fertilization and subsequent development. More (P<0.05) oocytes formed pronucleus and develop to the morula and blastocyst stages after inseminated with sperm treated with heparin than after inseminated with sperm treated with theophylline. The pregnancy rate after embryo transfer was higher after heparin treatment than after theophylline treatment, but did not differ significantly. There was no significant difference of offspring delivery between two groups. In conculsion, theophylline and heparin can be used for enhancing the efficiency of IVP system for Hanwoo. Considering characteristics of these substance, theophylline may be useful in the artificial insemination system, which requires vigorous sperm motility. While, heparin supporting sperm viability in vitro can be effectively used for improving in vitro-fertilization system.
        4,000원
        2607.
        2000.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        These experiments were conducted to examine the effects of theophylline, pentoxifylline and heparin on frozen-thawed Hanwoo sperm for enhancing motility and viability of sperm. Frozen-thawed semen collected from one bull was treated in TALP(tyrode-albuminlactate-pyruvate) containing varous concentrations of theophylline and pentoxifylline. After incubated at 5% CO2 in air atmosphere for 6 hours, the motility of sperm after the treatments was characterized by CASA(computer aided semen analysis) system. When monitored notility(MOT) and curvilinear velocity(VCL), theophylline and pentoxifylline exerted their optimal action at the concentration of 30 mM and 3 mM, respectively. No difference of sperm motility was observed when the sperm was treated with both substances compared with a single treatment of each substance. Comparison was then made for evaluating the effect of theophylline and / or pentoxiophylline on the motility and viability of significant treatment effects of each substance, high MOT and VCL values were detected in sperm treated with theophylline. In the case of sperm viability examined by an eosin-nigrosin staining, however, a significant decrease was found after the combined treatment of theophylline+pentoxyphilline than after the treatment with heparin alone or no treatment(P<0.05). In conclusion, theophylline, pentoxiphylline or heparin can be used for enhancing the motional characteristics and viability of frozen thawed Hanwoo semen. Considering characteristics of these substances, theophyline may be useful in the artificial insemination system, which requires vigorous sperm motility. While, heparin supporting sperm viability in vitro can be effectively used for improving in vitro-fertilization system.
        4,000원
        2608.
        2000.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to investigate the effects of quiescent treatment of donor cells and activation treatment time of recipient cytoplasm on nuclear remodeling and in vitro development of somatic cell-cloned bovine embryos. Serum starved, confluent and nonquiescent cycling adult skin cells were teansferred into enucleated oocytes. Nuclear transfer oocytes were activated at 30 min, 1 and 2 hrs after electrofusion. Some nuclear transfer embryos(23% to 35%) extruded a polar body, which was not affected by quiescent treatment of donor cells and activiation time of recipient cytoplasm. About 68% of nuclear transfer embryos fused with a serum starved cells has a chromatin clump, but which was not different from embryos fused with confluent(51%) and nonquiescent(47%) cells. The proportion of embryos with a single chromatin clump was sightly increased when nuclear transfer embryos were activated within 30 min after fusion(69%) compared to those were activated at 1 and 2 hrs after fusion, but there was not significantly different. Development rates to the blastocyst stage were 8.6% and 15.9% when serum starved and confluent cells were transferred, which were higher than that of control group. Developmental rate to the blastocyst stage was higher in embryos were activated within 30 min after fusion (17.3%) compared to those of embryos were activated at 1 and 2 hrs after fusion (P<0.05). From the present result, it is suggested that quiescent treatment of donor cells and activation time of recipient cytoplasm can affect the in vitro development. Quiescent plasm activation within 30 min after fusion could increase the number of embryos with a normal chromation structure, which results in increased in vitro development.
        4,000원
        2609.
        2000.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        1998년 11월부터 1999년 12월까지 13개월 동안 대형 수생식물인 애기부들의 분해와 분해 과정에 따른 각 기관별 영양염류 함량의 변화를 조사하였다. 13개월 후 잎, 줄기, 지하경의 잔존량은 각각 34.7%, 59.2%, 7.2%로 줄기의 분해가 가장 느렸고 지하경의 분해가 빠른 것으로 나타났다. 분해상수는 잎, 줄기, 지하경이 각각 1.06, 0.52, 42.63yr-1이었다. 잎, 줄기, 지하경의 초기 영양염류 함량은 질소 11.5,
        4,000원
        2611.
        2000.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        감잎의 메탄올 추출물은 농도에 비례해서 지질의 과산화를 크게 억제하였으며, 이들의 용매로 더 분획하여 얻은 헥산, 클로로포름, 에틸아세테이트, 부탄올 및 물 획분도 농도에 비례하여 항산화 효과가 관찰되었다, 이들중 가장 활성이 컸던 획분은 클로로포름과 에틸아세테이트 획분이었다. 한편 감잎의 열탕추출물과 감잎 탄닌의 경우도 농도에 비례해서 큰 항산화 효과가 관찰되었으며, 항돌연변이 및 암세포 증식억제 효과에서와 마찬가지로 열탕추출물에 비해 감잎 탄닌이 보다 높은 항산화 활성을 나타내었다. 이는 감잎의 열탕추출물에 함유된 탄닌의 농도에 기인하리라 생각되며, UV, IR, HPLC등을 이용하여 감잎으로부터 추출한 추출물이 탄닌임을 확인하였다.
        4,000원
        2612.
        2000.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        디지털형 압전/전왜 액츄에이터 응용을 위하여 상경계(반강유전상/강유전상) 조성인 Pb0.94Y0.04[(Zr0.6Sn0.4)0.915Ti0.085]O3 (PYZST) 계를 택하여 과잉 PbO의 첨가량 및 소결 조건 변화에 따른 상전이 특성, 유전 특성 및 전기장 유기변형 특성을 연구하였다. 사방정 구조를 갖는 PYZST 세라믹스에서 과잉 PbO 첨가에 따른 결정구조의 변화는 거의 확인되지 않았으나, 소결 후 입자가 약간 작아지며 둥근 형태로 변화하였고 첨가량 증가에 따라 적정 소결온도는 감소하였다. 과잉 PbO의 첨가량이 증가함에 따라, 분극측정시 반강유전상이 보다 안정되는 경향을 보였고, 전계유도변형 측정시 인가전기장 제거상태에서의 변형의 형상기억성이 감소하고 디지털형 변형곡선 특성이 강화되었다. 또한 최대 유전상수와 전계 유기변형량은 감소하였으나 반면 상전이(반강유전상↔강유전상) 전기장 및 비저항은 증가하는 경향을 나타냈다. 이러한 결과는 과잉으로 첨가된 PbO에 의한 격자 결함반응 및 분역벽 이동 거동 가능성과 연관시켜 설명하였다.
        4,000원
        2613.
        1999.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Organic semiconductors based on conjugated thiophene oligomer have great potential to be utilized as an active layer for electronic and optoelectronic devices. In this study, a conjugated oligomer such as α-sexithiophene (α-6T) thin films was prepared by the Organic Molecular Beam Deposition (OMBD), and various electrode materials were also deposited by a simple vacuum evaporation, respectively. Those films were photolithographically patterned for the electrical measurements. Electrical charact-erization of the thin film transistor with various channel length were executed and the field effect mobility of these thin film transistors were also calculated by the formula using the experimental data.
        3,000원
        2614.
        1999.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Interfacial properties of electrode and organic thin layer is one of the most important factor in performing a Light Emitting Diodes(LED). Phthalocyanine copper was used as a buffer layer to improve interface characteristic, so that device efficiency was improved. In this study, LEDs were fabricated as like structures of Indium-Tin-Oxide (ITO) / N,N' -Diphenyl-N,N'-di(m-tolyl)-benzidine (TPD) / 8-Hydroxyquinoline aluminum(Alq) / Aluminum(Al) and Indium-Tin-Oxide(ITO) / N,N'-Diphenyl-N,N' -di(m-tolyl)-benzidine(TPD) / 2-(4-Biphenylyl)-5(4-tert-butyl-phenyl)-1,3,4-oxadiazole(PBD) / Aluminum(Al). In these devices, CuPC was layered at electrode/organic layer interface. As position is changing and thickness is changing, devices showed characteristic luminescence efficiency and luminescence inensity respectively. We showed in this study that luminescence efficiency was improved with CuPC layer in LEDs. The efficiency of device with layer CuPC is higher than that of 2 layer CuPC. However, the luminescence of 2 layer CuPC device got higher value.
        4,000원
        2616.
        1999.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The Purpose of this Study is to find the Modern Movements which had done important roles on the development of modern church architecture and sacred art in the first half of 20th century. I had investigated the background and process of the movements, and analyzed the buildings which represented the movements. And I compared the architectural fruits of 'Riturgical Movement' and 'L' art Sacré Movement. The results are summarized as follows : First, there are two important movements in Catholic church in the backgrounds of the innovative changes of modern church architecture, Those are 'Riturgical Movement' which pursuits to establish a closer relation between clergy and congregation, and to make the positive participants in the service not mere observers and 'L' art Sacré Movement' which pursuits to accept modern secular art into church. Second, both movements had been developed on the bases of the theological studies with tow monasteries - Benedictine Order and Dominican Order - as leader. And the main concept was a kind of revival movement which recovers the Christian tradition. Third, The two movements began from the different themes and in the different regions. But they exerted influences each other, and achieved successful fruits in the Catholic churches of England and Swiss in 1960'. Fourth, 'Riturigical reformation' and 'Acceptance of modern art' had been officialized and generalized through the second Vatican Council(1962-1965).
        5,200원