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        검색결과 157

        61.
        2012.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        An unmanned aerial vehicle (UAV) is a powered aerial vehicle that does not carry a human operator, uses aerodynamic forces to provide vehicle lift, can fly autonomously or be piloted remotely, can be expendable or recoverable, and can carry a lethal or no
        4,000원
        62.
        2012.03 구독 인증기관 무료, 개인회원 유료
        Cytokines are known to function as regulatory molecules that can be produced by virtually every nucleated cell type in the body, including lymphocytes, monocytes/macrophages, epithelial cells, fibroblasts, and many others. Cytokines include lymphocyte-derived factors (lymphokines), monocyte-derived factors (monokines), hematopoietic factors (colony-stimulating factors), connective tissue/ growth factors, and chemotactic chemokines. Cytokines released in response to infection can affect tumor development in different ways. When exposed to infectious agents, cytokines are secreted by sentinel cells, such as macrophages and dendritic cells. These cytokines include interleukin 1 (IL-1) and tumor necrosis factor-α, as well as others, such as IL-6, IL-12, and IL-18. When released in sufficient quantities, these molecules can cause inflammation. Chronic inflammation is highly associated with tumor initiation, promotion, and progression. In this article, we review the roles and mechanisms of cytokines in tumor development.
        4,300원
        63.
        2011.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 환경스트레스 저항성이 증진된 페튜니아를 개발하기 위하여 NDPK2유전자 도입 형질전환 계통 NDPK2-7-1와 SOD2 유전자 도입 형질전환 계통 SOD2- 2-1-1-35간의 교잡에 의해 획득된 후대들의 비생물적 스트레스 저항성을 조사하기 위해 수행되었다. 비 생물적 스트레스 유발원인 메틸바이올로젠(methyl viologen, MV) 100 μM과 200 μM 처리에서 교잡후대들은 그들의 교배 모본 SOD2 유전자나 NDPK2 유전자가 단독으로 도 입된 형질전환 계통이나 비형질전환체 보다 메틸바이 올로젠에 의한 피해를 적게 받았다. 이는 SOD2 유전 자나 NDPK2 유전자가 단독으로 도입된 형질전환 계 통간 교잡에 의해 획득된 후대들이 그들의 교배모본 (SOD2 유전자나 NDPK2 유전자가 단독으로 도입된 형질전환 계통)이나 비형질전환체 보다 산화적 스트레 스에 대한 저항성이 증진되었음을 증명해 준다고 할 수 있다. 이들 교잡후대들은 초장 등 11종류의 양적형질의 특성이 비형질전환체에 비해 약간 길거나 짧긴 하였지 만 비형질전환체와 거의 유사하였으며, 꽃 색갈이나 모양 또한 그들의 교배모본 (SOD2 유전자나 NDPK2 유전 자가 단독으로 도입된 형질전환 계통)이나 비형질전환 체와 차이가 없었다.
        4,000원
        64.
        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
        65.
        2011.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        An Unmanned Aerial Vehicle (UAV) is a powered pilotless aircraft, which is controlled remotely or autonomously. UAVs are an attractive alternative for many scientific and military organizations. UAVs can perform operations that are considered to be risky
        4,200원
        66.
        2011.06 구독 인증기관 무료, 개인회원 유료
        Naturalness assessment can be utilized as a criterion to evaluate performance of preferred color corrections and to compare naturalness of images reproduced by displays. This paper presents a new model to assess naturalness based on three dimensional color space. Experimental results indicate that the proposed model outperforms three previous models proposed for the naturalness assessment.
        4,000원
        67.
        2010.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        원자전달 라디칼 중합을 이용하여 poly(epichlorohydrine) (PECH)를 주사슬로 한 양친성 가지형 공중합체를 합성하였다. PECH로부터 poly(methyl methacrylate)(PMMA) 및 poly(butyl methacrylate)(PBMA)의 가지형 중합이 성공적임을 1H NMR과 FT-IR분석을 통해 확인하였다. 합성한 가지형 공중합체에 KI나 LiI 염을 도입하였을 때, ether 신축진동 피크가 낮은 wavenumber영역으로 이동하였으며, 이는 배위결합 상호작용 때문이다. PECH-g-PBMA 복합체의 이온 전도도는 PECH-g-PMMA 복합체에 비해 항상 높게 나타났는데, 이는 고무상인 PBMA 사슬의 높은 이동성으로부터 기인한 것으로 확인되었다. 최고 이온전도도 값은 질량비 10 wt%의 KI가 도입된 PECH-g-PBMA 전해질체에서 2.7 × 10 -5 S/cm로 나타났다.
        4,000원
        68.
        2010.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Reliability has been considered as a one of the major design measures in various industrial and military systems. The main objective is to suggest a mathematical programming model and a hybrid parallel genetic algorithm(HPGA) for the problem that determin
        4,000원
        69.
        2008.10 구독 인증기관·개인회원 무료
        Varroa destructor Anderson & Trueman is the most injurious parasitic pest of honeybee in the world. Varroa mites had been originally external parasites of Asian honeybee (Apis cerana Fab.) in south eastern Asia. They jumped to European honeybees (Apis mellifera L.) by 1963. Since then they have killed millions of European honeybee colony, which might be susceptible to them, in Asia, Europe, America, and Africa. Also in Korea since Varroa mites were first found in 1968, they have been destructive pests in most of A. mellifera apiaries. Varroa destructor commonly infesting the European honeybees was classified in 2000 as a different species from the Varroa jacobsoni originally identified on Asian honeybees. Varroa mites not only feed the haemolymph of bees, but also introduce virulent viral diseases, and interrupt the development of bee colony. The other external parasitic mite, Tropilaelaps clarea Delfinado & Baker, which was introduced in 1994 from China, has widely spread and also brought damages on honeybees.
        71.
        2008.05 구독 인증기관·개인회원 무료
        Bumblebees are important pollinators in greenhouse and have colonized all parts of the World. In Korea, the value of bumblebees is increasing as pollinator. However, the more recent use of reared colonies may ultimately allow pathogens to spread to peripheral areas for bumblebees. Generally, bumblebees are hosts to a large number of parasites which are mites, flies, protozoa, fungi, virus and bacteria. For most of these, very little is known about their effects against host insect, epidemiology or evolutionary ecology. So, we report pathogenic bacteria isolated from Bombus terrestris and B. ignitus at first time in Korea. Bacillus fusiformis and Klebsiella oxytoca are isolated from B. terrestris and confirmed with 16S rRNA gene nucleotide comparison in NCBI genebank. Pathogenicity of B. fusiformis was 35~40% against B. terrestris. Pantoea dispersa and K. oxytoca are isolated from B. ignitus and confirmed with 16S rRNA gene nucleotide comparison in NCBI genebank. Pathogenicity of these species were 35~40% against B. ignitus. These pathogenicity are considered as low-level.
        72.
        2008.05 구독 인증기관·개인회원 무료
        A new species, Hatchiana n. sp., is confirmed by morphological and molecular data. The genus Hatchiana Fender, 1966 belonging to Podabrini LeConte, 1881 is distinguished by the shape of tarsal claws: all tarsal claws with blunt tooth in both sexes. The genus was recognized as a subgenus of Podabrus Westwood, 1838. Recently, however, Hatchiana was suggested as separated genus. The genus Hatchiana was known as 12 species in Palaeartic region including three species from Korea. In this study, we found Hatchiana n. sp. from several areas of Taean-gun, Chungcheongnam-do, Korea. This new species is different from closely relative species, Hatchiana jirisanensis (Kang & Kim, 2000) by following morphological characters: size of compound eye, length of antennae, shape of pronotum, shape of scutellum, and shape of aedeagus. Also, we compare the DNA barcoding region (the former region of CO1 gene) between these two species as molecular characters. In result, Hatchiana n. sp. is distinct from Hatchiana jirisanensis Kang & Kim by discrepancy of three percents in CO1 sequence. Therefore, the Korean Hatchiana is confirmed as four species, adding Hatchiana n. sp.
        73.
        2007.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        본 연구는 사용 후 핵연료의 금속전환 공정에서 발생되는 폐용융염을 고형화하는 방법으로 실리카 함유 무기물을 이용하여 폐용융염을 열적, 수화학적 안정한 화합물로 전환하는 방법을 제안하였다. 실리카 함유 무기물(SAP)은 일반적인 sol-gel process로 합성되었으며, 및 로 구성된다. 제조된 SAP을 에서 폐용융염과 반응시켜 각 금속염화물에 대한 반응특성 및 열안정성을 조사하고, PCT 침출시험법을 이용하여 수화학적 안정성을 평가하였다. LiCl은 와 로, CsCl는 CS-aluminosilicate와 로, 는 로, 는 로 전환되었다. 9시간 동안 반응시킨 후, 금속염화물의 전환율은 였으며, 까지 열감량은 1wt%이하로 TGA(Thermo Gravimetric Analysis)로 확인하였다. Cs 및 Sr의 침출속도는 로 매우 높은 내침출특성을 나타내었다. 이상의 결과로부터, SAP으로 명명된 안정화제(stabilizer)는 금속염화물로 구성된 폐용융염에 대해 매우 효과적인 것으로 판단된다. SAP을 이용한 폐용융염의 고화처리방법은 후속적인 안정성의 검증과정을 통하여 폐용융염의 최종처분부피를 최소화할 수 있는 대안적인 고화방법으로 고려될 수 있을 것으로 기대 된다.
        4,000원
        75.
        2004.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study is to analyze teachers' questioning patterns in EFL classes, and propose a new set of classification based on the interaction flow that a question initiates and the teachers' intention of questions in language classroom. Data were collected from five advanced EFL classes. Six categories of teacher questions were observed and two types of interactions following the initial questions were found. The interactions were usually opened by the teacher, which confirmed the general conception, and the types of interactions were mostly chosen by the teacher's preference and the activity the class was doing.
        6,300원
        78.
        2001.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        5,100원
        79.
        1998.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        6,700원
        80.
        1995.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        A velocity inhomogeneity, which is defined as a regional preponderence of either radial or tangential orbits, is searched with a new technique for the Coma cluster of galaxies. It is found within ~2h-1 Mpc from the cluster center that the Coma shows conspicuous inhomogeneities in velocity and that the inhomogeneities are real at a 99% level of confidence. Even in the central region (7' - 30' from the center), zones that are dominated by radial and tangential orbits are distinguishable. Defining the cluster's 'equator' as the direction defined by the Coma-A1367 supercluster, tangential orbits dominate the 'polar' zones in the central region. Galaxies that are located in 30'-100' also inhomogeneous in velocity in that the 'polar' zones are mostly radial while the rest is nearly homogeneous. These results indicate that the Coma galaxies are exceedingly more radial in orbit, implying that merging or infalls are either still going on or an earlier virialization is likely to have occurred preferentially near the 'equator'. Incorporating the velocity inhomogeneity into mass estimators, the most appropriate mass is turned out to be 0.4×1015h-1M⊙ (R ≤ 0.6h-1 Mpc),and 1.0\times10×15h-1 M⊙ (R≤ 2.1h-1Mpc). The corresponding mass to blue light ratio on the average is ~300h. These estimates are consistent with Merritt (1987) and Hughes (1989) and the MILE is seemed to favour the mass-follows-light models than the uniform spread of dark matter throughout the cluster.
        4,900원
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