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Zusammenfassung Mit Hilfe von extrahierter DNS wurde der genetische «Marker» der Phagenresistenz auf phagensensible Bakterien übertragen.  相似文献   

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提出一种基于Arnold变换的图像hash算法。算法首先将原始图像经过Arnold置乱变换得到加密图像,然后将原始图像与加密图像的差值矩阵由若干混沌序列生成的伪随机矩阵进行调制,最后将调制后的结果矩阵进行量化判决以产生固定长度的图像Hash序列。仿真结果表明,该算法对JPEG压缩、低通滤波、图像缩放等操作有一定的鲁棒性。  相似文献   

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Zusammenfassung Die Kompetenz für intraspezifische Transformation beiNeisseria catarrhalis wird nachgewiesen. Als genetischer Marker wird Lys- gewählt und hohe Frequenzen von Protrotophen festgestellt.  相似文献   

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The primary aim of this paper is to select an appropriate power transformation when we use ARMA models for a given time series. We propose a Bayesian procedure for estimating the power transformation as well as other parameters in time series models. The posterior distributions of interest are obtained utilizing the Gibbs sampler, a Markov Chain Monte Carlo (MCMC) method. The proposed methodology is illustrated with two real data sets. The performance of the proposed procedure is compared with other competing procedures. © 1997 John Wiley & Sons, Ltd.  相似文献   

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Bayesian inference via Gibbs sampling is studied for forecasting technological substitutions. The Box–Cox transformation is applied to the time series AR(1) data to enhance the linear model fit. We compute Bayes point and interval estimates for each of the parameters from the Gibbs sampler. The unknown parameters are the regression coefficients, the power in the Box–Cox transformation, the serial correlation coefficient, and the variance of the disturbance terms. In addition, we forecast the future technological substitution rate and its interval. Model validation and model choice issues are also addressed. Two numerical examples with real data sets are given.©1997 John Wiley & Sons, Ltd.  相似文献   

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根据小单孢菌产生庆大霉素的生物合成机理,利用基因克隆方法从棘孢小单孢菌(Micromonospora echinospora)基因组中扩增出庆大霉素生物合成的关键酶基因—2-脱氧青蟹肌糖合成酶基因(GntB),并将其通过大肠杆菌/链霉菌穿梭质粒pIJ699转化原菌株,采用硫链丝菌素抗性基因启动子带动2-脱氧青蟹肌糖合成酶基因在棘孢小单孢菌细胞中实现了转化。  相似文献   

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根据PLC的特点以及它在控制系统中的优势地位,提出了利用PLC对CA6140车床的电气控制部分进行改造.首先,分析了继电器控制系统的工作原理和它的优缺点,并与PLC控制系统的优缺点进行比较,得出PLC控制系统的优越性.对CA6140车床的工作过程和控制要求进行具体分析,完成了PLC的改造、分配点、I/O接口图的绘制、梯形图的编译、以及程序的编写.最后,利用仿真软件对设计部分进行模拟仿真,以验证其设计的正确性.  相似文献   

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Summary Caldariella Acidophila, a thermophilic bacterium, converts porgesterone (1) to pregn-4-en-3,6,20-trione (2), 5a-pregnan-3, 6, 20-trione (3), pregn-4-en-20a-ol-3-one (4), pregn-4-6-ol-3, 20-dione (5) and pregn-4-en-6a-ol-3, 20-dione (6). Different patterns of these metabolites were obtained by modifying the incubation conditions and using differently treated biocatalysis.  相似文献   

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Summary After injection of PHA into the peritoneal cavity of rats, parietal mesothelial cells were transformed into hyaluronic-acid-producing signet-ring-cells.

Die Untersuchungen wurden mit Unterstützung der Deutschen Forschungsgemeinschaft durchgeführt.  相似文献   

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Transformation: a tool for studying fungal pathogens of plants   总被引:18,自引:0,他引:18  
Plant diseases caused by plant pathogenic fungi continuously threaten the sustainability of global crop production. An effective way to study the disease-causing mechanisms of these organisms is to disrupt their genes, in both a targeted and random manner, so as to isolate mutants exhibiting altered virulence. Although a number of techniques have been employed for such an analysis, those based on transformation are by far the most commonly used. In filamentous fungi, the introduction of DNA by transformation typically results in either the heterologous (illegitimate) integration or the homologous integration of the transforming DNA into the target genome. Homologous integration permits a targeted gene disruption by replacing the wild-type allele on the genome with a mutant allele on transforming DNA. This process has been widely used to determine the role of newly isolated fungal genes in pathogenicity. The heterologous integration of transforming DNA causes a random process of gene disruption (insertional mutagenesis) and has led to the isolation of many fungal mutants defective in pathogenicity. A big advantage of insertional mutagenesis over the more traditional chemical or radiation mutagenesis procedures is that the mutated gene is tagged by transforming DNA and can subsequently be cloned using the transforming DNA. The application of various transformation-based techniques for fungal gene manipulation and how they have increased our understanding and appreciation of some of the most serious plant pathogenic fungi are discussed. Received 9 May 2001; received after revision 2 July 2001; accepted 3 July 2001  相似文献   

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An analytical model has been developed in the present paper based on a square root transformation of white Gaussian noise. The mathematical expectation and variance of the new asymmetric distribution generated by white Gaussian noise after a square root transformation are analytically deduced from the preceding four terms of the Taylor expansion. The model was first evaluated against numerical experiments and a good agreement was obtained. The model was then used to predict time series of wind speeds and highway traffic flows. The simulation results from the new model indicate that the prediction accuracy could be improved by 0.1–1% by removing the mean errors. Further improvement could be obtained for non‐stationary time series, which had large trends. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

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生态创新是驱动经济发展方式转变的关键,是现代经济的基本特征。文章首先探讨了生态创新的内涵和特征,然后分析了经济发展方式转变的内容,在此基础上分别从宏观和微观层面研究了基于经济发展方式转变的生态创新动力因素,形成了市场机制、政府激励、科技推动、生态竞争四位一体的动力机制,以此来促进经济发展的转型升级。  相似文献   

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