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        검색결과 525

        261.
        2009.05 구독 인증기관·개인회원 무료
        Root knot nematode species, such as Meloidogyne hapla, M. incognita, M. arenaria and M. javanica are economically most notorious nematode pests, causing serious damage to the various crops throughout world. In this study, DNA sequence analyses of the D1-D3 expansion segments of the 28S gene in the ribosomal DNA were conducted to characterize genetic variation of the four Meloidogyne species obtained from Korea and United States. PCR-RFLP (Polymerase Chain Reaction-Restriction Fragment Length Polymorphism), SCAR (Sequence Characterized Amplified Region) marker and RAPD (Random Amplification of Polymorphic DNA) also were used to develop the methods for exact and rapid species identification. In the sequence analysis of the D1-D3 expansion segments, only a few nucleotide sequence variation were detected among M. incognita, M. arenaria, and M. javanica, except for M. hapla. The PCR-RFLP analysis that involves amplification of the mitochondrial COII and lrRNA region yielded one distinct amplicon for M. hapla at 500 bp, enabling us to distinguish M. hapla from M. incognita, M. arenaria, M. javanica reproduced by obligate mitotic parthenogenesis. SCAR markers successfully identified the four root knot nematode species tested. We are under development of RAPD primers specific to the three root knot nematodes found in Korea.
        262.
        2009.05 구독 인증기관·개인회원 무료
        Two cherry tomato plant cultivars (Lycopersicon esculentum Miller, cultivars ‘Koko’ and ‘Pepe’) were supplied with high (395 ppm), medium (266 ppm) and low (199 ppm) concentrations of nitrogen to determine the influence of nitrogen fertilization on development, cultivar preference and honeydew production by greenhouse whiteflies, Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae). The nitrogen, protein, andchlorophyll content of tomato leaves were higher in the high nitrogen supplied plants than in the medium or low nitrogen supplied plants, but the sugar content showed an inverse relationship. The developmental times of eggsand nymphs decreased as the nitrogen concentrations increased in both cultivars. The preference of T. vaporariorum was compared by counting the number of eggs deposited on leaves in choice and non-choice tests. In the non-choice test, no significant nitrogen treatment effects were observedbut the upper plant stratum was preferred for egg laying. In the choice test, there were significant main effects of cultivar and nitrogen concentration. T. vaporariorum laid eggs more on leaves of plants with higher nitrogen at the upper stratum. In both experiments, T, vaporariorum preferred the ‘Koko’ cultivar to the ‘Pepe’ cultivar. The honeydew production of T. vaporariorum nymphs increased with decreasing nitrogen treatment concentrations. The largest honeydew production was detected in the ‘Pepe’ cultivar grown at low nitrogen concentration. It is concluded that cultivar ‘Pepe’ had an advantage over ‘Koko’ in term of T. vaporariorum management program in tomato greenhouses.
        263.
        2009.05 구독 인증기관·개인회원 무료
        The root zone applications of a systemic insecticide, carbofuran, were evaluated for their impacts on the brown planthopper, Nilaparvata lugens (Stål), and spider populations in the greenhouse and rice paddy fields. In the green house experiments, no BPH nymphs were hatched at root zone treated on 40 to 50 day-old rice, while around 20 to 54 nymphs per pot were emerged in broadcasting and foliar spray treatments. This indicates that the root zone treatment can kill the eggs of BPH effectively. This is the first study ever demonstrated the high egg mortality of BPH due to the root-zone application. In the field experiments, the density of BPH in root zone treated plots were four to six times lower than in broadcasting and foliar spray plots at the 21 days after application. The BPH outbreaks and hopper-burns were observed at all treatments except the root zone treated plot at the 28 days after application. The root-zone application did not impact on the spider population, while foliar spray killed most of all spiders just one day after application. The densities of spider in foliar spray plots were always lower than in root-zone treated and control plots. The results indicated that the root-zone application of carbofuran can control BPH effectively without adverse effects to the spiders inhabited on the paddy field.
        267.
        2008.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study is a follow-up of Hwang's (2007) empirical study, which investigated the role of awareness in Korean high school students' subsequent learning of the English passive. Hwang (2007) found the positive relationship between awareness and subsequent processing of the target structure and claimed the crucial role of awareness in successful second language learning. The present study explores whether the effects of awareness retain six months after the first post-exposure task of Hwang (2007), which was performed one day after the instruction. The results of the present study revealed the retention of the effects of awareness in the written production task as well as in the multiple-choice recognition task. However, no significant differences were found between the passive group, who were consciously aware of the target structure through a reading text and brief explanation about the English passive, and the preposition group whose attention could be implicitly drawn to the target structure through the reading text only. The results cannot fully support Schmidt's noticing hypothesis and can also be interpreted as providing evidence for the dissociation claim that L2 learning can take place implicitly without conscious awareness.
        5,200원
        270.
        2008.10 구독 인증기관·개인회원 무료
        Root zone application of several systemic insecticides was tested for control of the brown planthopper, Nilaparvata lugens (Stål), in Vietnam and Korea. In Vietnam, the results indicated that carbofuran showed the highest nymphal mortality in all experiments, followed by imidacloprid and carbosulfan. When the insecticides were applied on 10-day old rice, carbofuran was shown almost 100% N. lugens mortality at six days after treatment and the efficacy was extended to twelve days after application. In Korea, various root-zone application methods were tested with carbofuran and carbosulfan. The results showed that carbofuran was the most active in reducing the egg hatching rates. When root-zone treated on 40-50 day-old rice in a greenhouse, no nymphs were hatched in carbofuran treated pots, while average of 20 nymphs were emerged in carbofuran broadcasting pots. Especially the number of nymphs emerged in carbosulfan foliar spray was 54 nymphs per pot even at the eight day after application, which was higher than in control pots. This is the first study ever demonstrated the high egg mortality of N. lugens on rice due to the root-zone application of insecticides.
        273.
        2008.03 구독 인증기관 무료, 개인회원 유료
        We have previously produced transgenic (TG) mice expressing the human lactoferrin (hLF), interleukin-10 (hIL-10), and thrombopoietin (hTPO) proteins in the milk. In this study, we examined whether simple crossbreeding between two kids of a single transgenic mouse can produce double transgenics co-expressing two human proteins.. The hLF male, and the hIL-10 male were crossbred with the hIL-10 and hTPO females, and the hTPO female, respectively. PCR analysis for genotyping showed 32%, 23% and 24% double transgenic rates for hLF/hIL-10, hLF/hTPO, and hIL-10/hTPO transgenes, respectively. We analyzed the expression levels of the human proteins from double transgenic mice and compared those with their single transgenic siblings. All double transgenic co-expressed two human proteins at comparable levels to singles', unless hTPO was not co-expressed: for hLF, 1.1 mg/ml in hLF/hIL-10, whereas 0.5 mg/ml in hLF/hTPO; for hIL-10, 4.1 mg/ml in hIL-10/hLF, whereas 1.4 mg/ml in hIL-10/hTPO. Ihe downregulation of hTPO to half level of singles' was observed in double transgenic mice. The possible reason why hTPO co-expressed might lead to down-regulation of another human protein was discussed. These results suggested that double transgenic generated by crossbreeding between two singles' could be useful system for bioreactor.
        4,000원
        275.
        2007.12 구독 인증기관 무료, 개인회원 유료
        Field sequential 액정 디스플레이(FSLCD)는 컬러필터를 사용하지 않아 높은 투과율 특성을 보이고 광 원으로 LED를 사용함으로써 색재현성이 매우 우수하다. 하지만 FSLCD(60Hz 구동)를 실현하기 위해서는 액정의 응답속도가 5ms이하로 고속응답 특성을 보여야 한다. 따라서 본 논문에서는 고속응답 ECB(electrically controlled birefringence) 셀의 최적 구조를 연구하여 5ms 이하의 응답시간을 얻었다. 그리고 ECB 모드에서 높은 구동전압과 시야각을 개선하기 위해 필름 보상을 연구하였다. 판상형 액정필름(discotic film)과 TAC(triacetyl cellulose) 필름의 위상차 값을 최적화함으로써 구동전압을 5V로 낮추고 상하좌우에서 160° 이상(CR>10:1)의 시야각을 실현하였다.
        4,000원
        276.
        2007.12 구독 인증기관 무료, 개인회원 유료
        In this study, we exarnined the effects of different concentrations of red pepper seed (0%, 1%, 3%, 5%, and 7%) on pH, total acidity, color, reducing sugar content, total microbes, lactic acid bacteria, and sensory quality, in terms of prolonging the shelf-life of kimchi. The additions of red pepper seed resulted in higher pH leveIs, while total acidity was lower than that of the control. The kimchi with red pepper seed had higher reducing sugar contents than the control. Furthermore, the kimchi with red pepper seed showed higher b-values than the control. During fermentation, the arnounts of lactic acid bacteria and total microbes were higher in the kimchi with red pepper seed than in the control, and the higher ratios resulted in higher quality kimchi. The additions of red pepper seed also resulted in changes of color, flavor, taste, and texture, having a large influence on overall product quality. In conclusion, in terms of preservation and consumption, the 3% and 5% red pepper seed concentrations offered enhanced shelf-life and better quality kimchi products.
        4,000원