• 제목/요약/키워드: Ping

검색결과 1,340건 처리시간 0.035초

Isolation and Identification of Newly Isolated Antagonistic Streptomyces sp. Strain AP19-2 Producing Chromomycins

  • Wu, Xue-Chang;Chen, Wei-Feng;Qian, Chao-Dong;Li, Ou;Li, Ping;Wen, Yan-Ping
    • Journal of Microbiology
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    • 제45권6호
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    • pp.499-504
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    • 2007
  • A new antagonistic strain of actinomycete, designated AP19-2, was isolated from the feces of giant pandas inhabiting the Foping National Nature Reserve in China. Cultural characteristic studies strongly suggested that this strain is a member of the genus Streptomyces. The nucleotide sequence of the 16S rRNA gene of strain AP19-2 evidenced profound similarity (97-99 %) with other Streptomyces strains. Two pure active molecules were isolated from a fermentation broth of Streptomyces sp. strain AP19-2 via extraction, concentration, silica gel G column chromatography, and HPLC. The chemical structures of the two related compounds (referred to as chromomycin $A_2$ and chromomycin $A_3$) were established on the basis of their Infrared spectra (IR), High Resolution Electrospray Ionization Mass Spectrometry (HR-ESI-MS), and Nuclear Magnetic Resonance (NMR) data, and by comparison with published data.

현대(現代) 중국(中國)의 토지소유변화(土地所有變化)에 관한 연구(硏究) (A study on Land Tenure Systems in Current China)

  • 김재홍;이종수
    • 농업과학연구
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    • 제26권1호
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    • pp.84-99
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    • 1999
  • In China, primary purpose of policy concerning land tenure system was to maintain social homogeneity among people and growth of productivity. Even before reformed by Deng Shao Ping's government, left wing who had placed more importance on the social unity. When they gained political power, pressing against market oriented agricultural policy for the collective farming system. However right wing prefered to adopt the productivity oriented policy, which might lead to individualized farming system at the cost of social unity. Since Chinese government following principles of social economy put more weight on social unities rather than productivity growth, farming system and rural community became developed into homogeneous structure across the nation before Deng Shao Ping's reform. Process for People's Commune, followed by first and then second level coperations starting from group farming so called Hozozo, was historical reflection of developing such land tenure system. However, even under People's Commune, farmers' efforts could be found to increase their own productivity along with emerged private farming, in which Posandoho with week private farming system was gradually developed into Pogandoho. As Deng's government encouraged farmers to increase productivity through the market oriented measure, there had been wide spread of Pogandoho among the farmers even before legal desolution of Peoples' Commune was realized.

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수중운동체의 목표추적시스템에 적합한 유도론 선정에 대한 연구 (A Study on the Guidance Law Suitable for Target Tracking System of an Underwater Vehicle)

  • 윤근항;이기표;여동진
    • 대한조선학회논문집
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    • 제42권4호
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    • pp.299-306
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    • 2005
  • To determine a guidance law which is suitable for Target Tracking System(TTS) of an underwater vehicle, the performance (hitting probability) of TTS were calculated with four different guidance schemes, considering underwater vehicle's manoeuvrability and characteristics of seeking equipment such as sonar To evaluate the performance of TTS with each guidance law, numerous target-tracking simulations of underwater vehicle were performed under the condition of target's various motion scenario. Furthermore, the effect of sonar characteristics to the performance of guidance law in TTS was studied by changing parameters of sonar such as frequency of ping and detecting error of target. The pursuit-tail guidance law showed the best performance among four different guidance laws. Complex motion of target from straight line to turning circle and zigzag movement, low frequency of sonar ping and large detecting error of target decreased the hitting probability.

Kinetic Study on the Enzymatic Production of D-Alanine from D-Aspartic Acid

  • Lee, Jae-Heung;Sung, Moon-Hee;Jeon, Yeong-Joong
    • Journal of Microbiology
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    • 제40권1호
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    • pp.33-37
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    • 2002
  • An enzymatic reaction for the production of D-alanine from D-aspartic acid and pyruvate as substrates by a thermostable D-amino acid aminotransferase (D-AAT) was investigated at various conditions In the temperature range of 40-70$\^{C}$ and pH range of 6.0-9.5. The D-AAT was produced with recombinant E. coli BL21, which hosted the chimeric plasmid pTLK2 harboring the D-AAT from the novel thermophilic Bacillus sp. LK-2. The enzyme reaction was shown to follow the Ping Pong Bi Bi mechanism. The K$\_$m/ values for D-aspartic acid and pyruvate were 4.38 mar and 0.72 mM, respectively. It was observed that competitive inhibition by D-alanine, the product of this reaction, was evident with the inhibition constant K$\_$i/ value of 0.1 mM. A unique feature of this reaction scheme is that the decorboxylation of oxaloacetic acid, one of the products, spontaneously produces pyruvate. Therefore, only a catalytic amount of pyruvate is necessary for the enzyme conversion reaction to proceed. A typical time-course kinetic study skewed that D-alanine up to 88 mM could be produced from 100 mM of D-aspartic acid with a molar yield of 1.0.