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Utiliza??o de técnicas estatísticas em duas revistas de fruticultura
Cantuarias-Avilés, Tatiana;Dias, Carlos Tadeu dos Santos;
Ciência Rural , 2008, DOI: 10.1590/S0103-84782008000800044
Abstract: the statistical techniques and statistical accessibility were analyzed in a sample collected from the original articles published between 1996 and 2006 by two fruticulture journals: the revista brasileira de fruticultura (rbf) and the french journal fruits. a total of 986 original articles were classified in 16 classes of statistical analyses, previously ordered by increasing degree of complexity. the complexity of statistical techniques used by both journals increased in time. along the 1996-2006 period, the articles published in the rbf journal utilized more complex statistical techniques, as well as experimental designs in randomized blocks, factorial, split plot and hierarchical arrangements, and the test of tukey for mean comparisons. in the articles published by the fruits journal the use of other parametrical tests and the duncan test was more frequent. in both journals the sas statistical software was most frequently utilized. readers of the rbf journal required a higher level of statistical knowledge to understand the techniques utilized in the articles.
Análise AMMI com dados imputados em experimentos de intera??o genótipo x ambiente de algod?o
Arciniegas-Alarcón, Sergio;Dias, Carlos Tadeu dos Santos;
Pesquisa Agropecuária Brasileira , 2009, DOI: 10.1590/S0100-204X2009001100004
Abstract: the objective of this work was to evaluate the convenience of defining the number of multiplicative components of additive main effect and multiplicative interaction models (ammi) in genotype x enviroment interaction experiments in cotton with imputed or unbalanced data. a simulation study was carried out based on a matrix of real seed-cotton productivity data obtained in trials with genotype x environment interaction carried out with 15 genotypes at 27 locations in brazil. the simulation was made with random withdrawals of 10, 20 and 30% of the data. the optimal number of multiplicative components for the ammi model was determined using the cornelius test and the likelihood ratio test onto the matrix completed by imputation. a correction based on the data missing in the cornelius procedure was proposed for testing the hypothesis when the analysis is made from averages and the repetitions are not available. for data imputation, the methods considered used robust submodels, alternating least squares and multiple imputation. for analysis of unbalanced experiments, it is advisable to choose the number of multiplicative components of the ammi model only from the observed information and to make the classical estimation of parameters based on the matrices completed by imputation.
Acurácia do modelo univariado para análise de medidas repetidas por simula??o multidimensional
Xavier, Lara Hoffmann;Dias, Carlos Tadeu dos Santos;
Scientia Agricola , 2001, DOI: 10.1590/S0103-90162001000200005
Abstract: in experiments using repeated measurements, when split plot designs are utilized the f test in relation to the subplot will have an exact f distribution only if the matrix of covariance satisfies the sphericity condition. the objective of this article was to verify throught simulation the accuracy of the analysis throught the observation of some cases when the matrix of covariance satisfies or not the sphericity condition. when the matrix of covariance was of the component type of variance and of compound symmetry, the sphericity condition was satisfied and the accuracy of the analysis adequate. this does not happen with other structures of the covariance matrix. in relation to the effects of parameters, depending on the magnitude of the values of the effects, they will interfere with the results of the tests, over estimating the effects when the amplitude of the effects is large.
Choosing components in the additive main effect and multiplicative interaction (AMMI) models
Dias, Carlos Tadeu dos Santos;Krzanowski, Wojtek Janusz;
Scientia Agricola , 2006, DOI: 10.1590/S0103-90162006000200009
Abstract: the additive main effect and multiplicative interaction (ammi) models allows analysts to detect interactions between rows and columns in a two-way table. however, there are many methods proposed in the literature to determine the number of multiplicative components to include in the ammi model. these methods typically give different results for any particular data set, so the user needs some guidance as to which methods to use. in this paper we compare four commonly used methods using simulated data based on real experiments, and provide some general recommendations.
Análise e quantifica??o do risco para a gest?o eficiente do portfólio agrícola das seguradoras
Ozaki, Vitor Augusto;Dias, Carlos Tadeu dos Santos;
Revista de Economia e Sociologia Rural , 2009, DOI: 10.1590/S0103-20032009000300001
Abstract: in the agricultural insurance, the presence of adverse events can compromise the financial health of the agricultural insurance companies. drought, for example, can affect not only one producer, but thousand of producers in a huge territorial extension. to skirt this problem, insurance companies diversify geographically their operations. this paper applies the cluster analysis in a corn yield data set for the regions of paraná state, considering the period from 1990 to 2005. in total, 39 groups were formed according to similar characteristics of expected yield and relative risk. based on one of insurability criteria, some high-risk regions were excluded, and groups were classified according to the degree of relative risk.
HARVEST TIME AND PHYSIOLOGIC QUALITY OF SEEDS IN IRRIGATED RICE (Oryza sativa cv. BRS RORAIMA) éPOCA DE COLHEITA E QUALIDADE FISIOLóGICA DE SEMENTES EM ARROZ IRRIGADO (Oryza sativa cv. BRS RORAIMA)
Oscar José Smiderle,Carlos Tadeu dos Santos Dias
Pesquisa Agropecuária Tropical , 2008, DOI: 10.5216/pat.v38i3.3487
Abstract: Harvest time is one of most important factors influencing rice seed characteristics for purpose of either planting or milling. With the objective to determine a proper harvesting time, irrigated rice seeds of cultivar BRS Roraima were harvested at 15, 22, 29, 36, 43 and 50 days after flowering (DAF), and assessed according to humidity, viability, dry mass of 1,000 seeds, whole grain yield, productivity and storability. Seeds harvested 29 DAF showed high quality and its productivity was equivalent to the subsequent periods. Seeds harvested 50 DAF showed good performance, except for whole grain yield. Harvests 15 and 22 DAF were unsuitable, reducing the physiologic quality of seeds, mill efficiency and high initial humidity. The adequate harvest time for cultivar BRS Roraima is between 29 and 43 DAF, when seeds present higher yield, dry mass, whole grain yield, physiologic quality and storability. KEY-WORDS: Physiologic quality; whole grain; humidity. A época de colheita é um dos fatores mais importantes que influenciam as características da semente de arroz, seja para semeadura ou para consumo. Com o objetivo de determinar a época adequada de colheita de arroz irrigado, para a cultivar BRS Roraima, sementes foram colhidas aos 15, 22, 29, 36, 43 e 50 dias após o florescimento (DAF) e avaliadas quanto à umidade, viabilidade, massa seca de 1.000 sementes, rendimento de gr os inteiros, produtividade e armazenabilidade. As sementes colhidas aos 29 DAF tiveram alta qualidade e a produtividade foi equivalente à dos períodos subseqüentes. Aquelas provenientes da colheita aos 50 DAF exibiram bom desempenho, exceto em rendimento de gr os inteiros. Colheitas realizadas aos 15 e 22 DAF s o impróprias, reduzindo a qualidade fisiológica das sementes, o rendimento de engenho e a alta umidade inicial. A época adequada de colheita para a cultivar BRS Roraima está entre 29 e 43 DAF, quando suas sementes apresentam maior produtividade, massa seca, rendimento de gr os inteiros, qualidade fisiológica e armazenabilidade. PALAVRAS-CHAVE: Qualidade fisiológica; gr os inteiros, umidade.
época de colheita e armazenamento de sementes de arroz produzidas no cerrado de Roraima. = Harvesting time and storage of rice seeds in savanna area of Roraima, Brazil.
Oscar José Smiderle,Carlos Tadeu dos Santos Dias
Agro@mbiente On-line , 2011,
Abstract: A época de colheita é um dos fatores mais importantes que influenciam as características da semente de arroz (Oryza sativa L.). Objetivou-se com o presente trabalho determinar a melhor época de colheita em fun o do período de armazenamento, produtividade, qualidade de sementes e rendimento de sementes inteiras no armazenamento de sementes de arroz BR IRGA 409. Para tanto foram avaliados o teor de água, viabilidade, massa seca de 100 sementes, rendimento desementes inteiras, produtividade e armazenabilidade das sementes produzidas em Boa Vista, RR. O delineamento experimental utilizado foi o inteiramente aleatorizado, em esquema fatorial (6 x 3) com quatro repeti es, sendo o primeiro fator as épocas de colheita (colheita aos 15; 22; 29; 36; 44 e 50 dias após o florescimento) e segundo fator os períodos de avalia o (zero; seis e doze meses). As sementes obtidas aos 15 e 22 dias revelaram-se inferiores em todas as variáveis estudadas. As sementes colhidas aos 29 dias mostraram boa qualidade, e a produtividade foi equivalente à dos períodos subseqüentes. Aquelasprovenientes da colheita realizada aos 50 dias exibiram qualidade física e fisiológica, exceto no rendimento de sementes inteirasno armazenamento. A melhor faixa de colheita foi a de 29 a 43 dias após o florescimento, quando as sementes apresentam maior qualidade fisiológica, maior massa seca de 100 sementes, maiores rendimentos de sementes inteiras e produtividade de sementes. As sementes de arroz colhidas apresentam e mantém a qualidade fisiológica no armazenamento. = Harvesting time is one of most important factors that have influence on rice seed characteristics. With the objective to determine the best harvest time concerning to storage period, productivity, seed quality and undamaged rice yield during storage of BR IRGA 409 rice seeds. In this way, the following parameters were assessed: water content, viability, dry mass of 100 seeds, undamaged seed yield, productivity and storability, being all produced in Boa Vista, RR. The experimental design utilized was completely randomized, in a factorial (6 x 3) scheme with four replicates, the first factor related to harvest times15; 22; 29; 36; 44 and 50 days after flowering and the second factor related to periods of evaluation (zero, six and twelve months). Seeds obtained 15 and 22 days after flowering were inferior in all parameters analyzed. Seeds harvested 29 days after flowering presented good quality, and productivity was equivalent to subsequent periods. Seeds obtained from harvest 50 days after flowering showed physical and physiological
Acurácia do modelo univariado para análise de medidas repetidas por simula o multidimensional
Xavier Lara Hoffmann,Dias Carlos Tadeu dos Santos
Scientia Agricola , 2001,
Abstract: Em experimentos com medidas repetidas, quando se utiliza o esquema de parcelas subdivididas, o teste F com rela o à subparcela, só terá distribui o F exata caso a matriz de covariancias atenda a condi o de esfericidade. O objetivo deste trabalho foi verificar por meio de simula es, a acurácia da análise através da observa o de casos em que a matriz de covariancias atende, ou n o, à condi o de esfericidade. Quando utilizadas as matrizes de covariancias do tipo componente de variancia e simetria composta, que atendem a condi o de esfericidade, a acurácia da análise foi satisfatória. O mesmo n o ocorreu com outras estruturas da matriz de covariancias. Com rela o aos efeitos dos parametros, dependendo da grandeza dos valores dos efeitos, estes influenciam o resultado dos testes no sentido de superestimar a indica o dos mesmos, isto quando o intervalo de varia o é grande.
Choosing components in the additive main effect and multiplicative interaction (AMMI) models
Dias Carlos Tadeu dos Santos,Krzanowski Wojtek Janusz
Scientia Agricola , 2006,
Abstract: The additive main effect and multiplicative interaction (AMMI) models allows analysts to detect interactions between rows and columns in a two-way table. However, there are many methods proposed in the literature to determine the number of multiplicative components to include in the AMMI model. These methods typically give different results for any particular data set, so the user needs some guidance as to which methods to use. In this paper we compare four commonly used methods using simulated data based on real experiments, and provide some general recommendations.
Tabela de vida de fertilidade de três espécies neotropicais de Trichogrammatidae em ovos de hospedeiros alternativos como critério de sele??o hospedeira
Dias, Nivia da Silva;Parra, José Roberto Postali;Dias, Carlos Tadeu dos Santos;
Revista Brasileira de Entomologia , 2010, DOI: 10.1590/S0085-56262010000100016
Abstract: the objective of this work was to select the factitious host that permit the best development of three neotropical trichogrammatidae species, trichogramma atopovirilia oatman & platner, 1983; trichogramma bruni nagaraja, 1983, and trichogrammatoidea annulata de santis, 1972, using the fertility life table on their respective hosts as a comparative parameter. mean generation time (t), net reproductive rate (ro), intrinsic rate of natural increase (rm) and the finite rate of increase (λ) were estimated. a fertility life table is useful to select the most adequate factitious hosts for the trichogrammatid species. corcyra cephalonica (stainton, 1865) (lepidoptera, pyralidae) was the most suitable factitious host for rearing of t. annulata and t. bruni; while anagasta kuehniella (zeller, 1879) (lepidoptera, pyralidae) and/or c. cephalonica were the most suitable hosts for t. atopovirilia. sitotroga cerealella (olivier, 1819) (lepidoptera, gelechiidae) presented a low capacity of population increase for the three species of parasitoids, therefore, being an inadequate species as a factitious host.
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