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Registros recuperados: 69
Primeira ... 1234 ... Última
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Mudanças na florística e estrutura de uma floresta decídua durante um período de quatro anos (1994-1998), na região do Triângulo Mineiro, MG Rev. Bras. Bot.
WERNECK,MÁRCIO DE SOUZA; FRANCESCHINELLI,EDIVANI VILLARON; TAMEIRÃO-NETO,EUGÊNIO.
As alterações na estrutura e na composição florística de um fragmento de floresta decídua foram descritas para um período de quatro anos (1994-1998), na região do Triângulo Mineiro, MG. Este fragmento, denominado Mata da Zilda, foi bastante perturbado por atividades humanas até 1993, sendo protegido a partir de 1994. Logo após a sua proteção, realizou-se um inventário das plantas lenhosas (CAP > ou = 10 cm) em 26 transectos de 50 x 6 m (0,78 ha). Quatro anos depois (1998), todos os transectos foram reavaliados e medidos os novos ingressos. Em 1994, foram identificadas 114 espécies, representando 46 famílias. A riqueza de espécies foi idêntica em 1998. Também, os valores do índice de Shannon (3,72) e a equabilidade (0,79) não diferiram significativamente...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Forest dynamics; Floristics; Structure; Fragment; Dry deciduous forest.
Ano: 2000 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84042000000400006
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Análise da estrutura de fragmentos florestais no Planalto Paulistano - SP Rev. Bras. Bot.
DISLICH,RICARDO; CERSÓSIMO,LUCIANA; MANTOVANI,WALDIR.
Neste trabalho é descrita a variação encontrada na estrutura de fragmentos florestais no Planalto Paulistano, sob diversos aspectos e em diferentes escalas de tamanho. Um censo do componente arbóreo dominante (PAP > ou = 50 cm) em duas áreas (0,5 ha e 0,2 ha) no interior de um fragmento florestal, a Reserva da Cidade Universitária "Armando de Salles Oliveira" (CUASO), Butantã, São Paulo, SP (aproximadamente 23°34'S, 46°43'W) incluiu 227 indivíduos de 50 espécies. Foi encontrada dominância absoluta total (Do) de 20,1 m².ha-1, índice de Shannon (H´) de 3,04 nats.ind-1 e equabilidade de Pielou (J´) de 77,79%. Em cada área, foram encontradas regiões de concentração de espécies pioneiras, secundárias e climácicas. As duas áreas apresentaram diferenças na...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Ombrophilous dense forest; Fragments; Structure; Diversity.
Ano: 2001 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84042001000300011
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Florística e estrutura de três trechos de uma floresta semidecídua na Estação Ecológica do Tripuí, Ouro Preto, MG Rev. Bras. Bot.
WERNECK,MÁRCIO DE SOUZA; PEDRALLI,GILBERTO; KOENIG,ROSSANA; GISEKE,LETÍCIA FARAH.
O presente estudo foi desenvolvido em três trechos de floresta semidecídua, que no passado tiveram usos diferenciados, localizados na Estação Ecológica do Tripuí (EET), Ouro Preto (MG), objetivando verificar as variações qualitativas e equantitativas das espécies arbóreas. As áreas 1 (A1) e 2 (A2) representam os trechos mais preservados da floresta, não havendo relatos de perturbação, como fogo ou retirada de madeira, nos últimos 30 anos. A área 3 (A3) representa o trecho sucessional mais jovem da floresta, onde houve uma antiga plantação de chá preto, abandonada há 40 anos. Foram demarcadas, em cada trecho, três parcelas de 10 x 30 m, onde foram amostrados todos os indivíduos vivos com perímetro a altura do peito (PAP) 3 5 cm. Os solos na EET foram...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Floristic; Structure; Semideciduous forest; Tripuí Ecological Station.
Ano: 2000 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84042000000100011
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Temporary effect of chiseling on the compaction of a Rhodic Hapludox under no-tillage Rev. Bras. Ciênc. Solo
Silva,Sâmala Glícia Carneiro; Silva,Álvaro Pires da; Giarola,Neyde Fabíola Balarezo; Tormena,Cássio Antônio; Sá,João Carlos de Moraes.
Mechanical chiseling has been used to alleviate the effects of compaction in soils under no-tillage (NT). However, its effect on the soil physical properties does not seem to have a defined duration period. The purpose of this study was to evaluate the behavior of the bulk density (BD) and degree of compaction (DC) at different soil depths, after chiseling in no-tillage, for one year. The experiment was performed in Ponta Grossa, Paraná State, Brazil, using an Oxisol (Rhodic Hapludox). Bulk density and DC were previously measured in an area under NT for 16 years, then immediately after chiseling (CHI) in May 2009, six months after chiseling (CHI6M) in October 2009 and one year after chiseling (CHI12M) in May 2010. In the layers 0.0-0.10, 0.10-0.20 and...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Soil compaction; Structure; Soil quality; Resilience.
Ano: 2012 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832012000200024
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A REVIEW ON SISAL FIBER REINFORCED POLYMER COMPOSITES AGRIAMBI
Joseph,Kuruvilla; Tolêdo Filho,Romildo Dias; James,Beena; Thomas,Sabu; Carvalho,Laura Hecker de.
ABSTRACT The global demand for wood as a building material is steadily growing, while the availability of this natural resource is diminishing. This situation has led to the development of alternative materials. Of the various synthetic materials that have been explored and advocated, polymer composites claim a major participation as building materials. There has been a growing interest in utilizing natural fibres as reinforcement in polymer composite for making low cost construction materials in recent years. Natural fibres are prospective reinforcing materials and their use until now has been more traditional than technical. They have long served many useful purposes but the application of the material technology for the utilization of natural fibres as...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Sisal fibre; Polymer; Composites; Structure; Properties.
Ano: 1999 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43661999000300367
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Tillering and biomass partitioning of Mombasa grass under nitrogen fertilization during regrowth R. Bras. Zootec.
Garcez Neto,Américo Fróes; Gobbi,Kátia Fernanda; Silva,Janielen da; Santos,Tiago Machado dos.
Biomass partitioning in forages is highly variable during plant development and with the rate of nutrient supply. This study was carried out with the objective to evaluate the tillering pattern and biomass partitioning of Mombasa grass (Megathyrsus maximus cv. Mombaça) subjected to rates of nitrogen (N) during regrowth. The treatments consisted of three weekly rates of N: control (without N supply), 25 and 50 mg dm-3 of N, which were evaluated by 1, 2, 4, 8, 16 and 32 days after defoliation. The design was of completely randomized blocks in a 3 × 6 factorial arrangement with three replicates. The number of tillers was measured and harvesting and weighting of the following morphological components were performed: leaf (leaf blades), pseudostem, stem base...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Forage; Morphology; Structure; Tiller.
Ano: 2012 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982012000800004
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Economic and social structures of water buffalo farming in Muş province of Turkey R. Bras. Zootec.
Işik,Mehmet; Gül,Mevlüt.
ABSTRACT The purpose of this study was to analyse the socio-economic structure of water buffalo farming in the province of Muş, in Turkey. The stratified sampling method was used to calculate sample size of buffalo farms in the Central, Korkut, and Hasköy districts of Muş province, where buffalo farming is widespread. Data were collected from the 94 farms by surveys in the 2013 production period. A single budget analysis method was used to calculate production cost and profit for water buffaloes. Plant production constituted 37.85% of the gross production value, while animal production accounted for 62.15%. The biggest share in the gross production value derived from water buffalo farming (45.71%). Fixed and variable costs were 51.44% and 48.56% of the...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Production cost; Profit; Structure.
Ano: 2016 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982016000700400
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Structure-Function Studies of EPSP Synthase from Pseudomonas aeruginosa Thai Agricultural
Sauders, J.E.; Carpenter, E.P.; Vaithanomsat, P.; Coggins, J.R.; Brown, K.A..
Palavras-chave: Structure; Function; Studies.
Ano: 2002 URL: http://anchan.lib.ku.ac.th/agnet/handle/001/5029
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THE VEGETATION OF A SEASONAL VÁRZEA FOREST IN THE LOWER SOLIMÕES RIVER, BRAZILIAN AMAZONIA Acta Amazonica
KLINGE,Hans; ADIS,Joachim; WORBES,Martin.
The species composition of the seasonal várzea forest growing on a bank of the Ilha de Marchantaria / lower Solimões-Amazonas River, Brazil was studied in an area of slightly less than one hectare. Two biomass plots were harvested. Forty-seven arboreal species representing 46 genera in 25 families were recorded. Tree density was 1086 per hectare. Total basal area was 45 m2 ha1. Mean species density was 6.5 ± 1.98 per 100 m2. The most abundant species were Crataeva benthamii(Capparidaceae), Laetia corymbutosa(Flacourtiaceae) and Vitex cymosa(Verbenaceae). The highest basal area per species was 10.2 m2 for Pseudobombax munguba(Bombacaceae). The common species are known to be typical floristic elements of the seasonal varzea forest. Above ground dry biomass...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Amazon; Bioelements; Biomass; Floodplain; Seasonal várzea forest; Species composition; Structure.
Ano: 1995 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59671995000400201
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Testa structure in Erythrina speciosa (Leguminosae): the role of the mucilaginous stratum in the acquisition of physical dormancy Acta Botanica
Magalhães,Camila Ribeiro; Oliveira,Denise Maria Trombert.
ABSTRACT Seeds of Erythrina speciosa (Papilionoideae) exhibit physical dormancy, but evidence has suggested that the proportion of impermeable seeds increases with storage. There are no records of structural variation in the testa of E. speciosa that justifies the difference in the percentage of seeds with physical dormancy. Therefore, the present study investigated the difference in permeability between mature seeds of E. speciosa that were freshly collected and those stored for 12 months. Seeds were examined for changes in testa structure that could result in differences in the percentage of seeds in physical dormancy. Thus, imbibition curves and water gaps were determined, and surface micromorphology, anatomy, and histochemistry of the testa were...
Tipo: Info:eu-repo/semantics/other Palavras-chave: Anatomy; Mucilaginous stratum; Physical dormancy; Seed coat; Structure.
Ano: 2020 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33062020000300592
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Revisiting hydropotes of Nymphaeaceae: ultrastructural features associated with glandular functions Acta Botanica
Tozin,Luiz Ricardo dos Santos; Rodrigues,Tatiane Maria.
ABSTRACT Hydropotes are specialized epidermal structures involved in water and mineral flux into and out of the plant body. We analyzed hydropote morphology of four species of Nymphaeaceae: Nymphaea caerulea, Nymphaea lotus, Nymphaea rubra, and Victoria amazonica. Leaf samples were processed following conventional techniques for plant anatomy and for scanning and transmission electron microscopy. We observed hydropotes comprising an elongated apical sharp-pointed portion with a base composed of two to three short specialized cells. In a later developmental stage the apical sharp-pointed portion was detached and the mature hydropotes comprised an upper lens-shaped cell, a bowl-shaped cell and a large foot cell. Ultrastructural analysis revealed that the...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Nymphaeae; Subcellular features; Structure; Trichomes; Victoria.
Ano: 2020 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33062020000100031
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Morfoanatomia e ontogênese dos frutos e sementes de Clusia lanceolata Cambess. (Clusiaceae) - doi: 10.4025/actascibiolsci.v32i4.3567 Biological Sciences
Campana, Regiane Cristina; UEM; Mourão, Káthia Socorro Mathias; UEM; Marzinek, Juliana; UEM.
Clusia lanceolata Cambess é espécie arbustiva da Mata Atlântica. Caracteriza-se por ser dioica, com flores estaminadas e pistiladas grandes, vistosas, de coloração rosa, apresentando a parte interna vinácea. Foram descritos aspectos morfológicos e estruturais dos frutos e sementes dessa espécie, visando classificar corretamente o seu tipo de fruto e, também, confirmar a origem do apêndice carnoso que envolve as sementes. O material botânico utilizado constou de flores em antese e frutos, em quatro estádios de desenvolvimento, coletados de dois espécimes. Os estudos morfológicos e anatômicos foram realizados segundo técnicas usuais. O fruto é cápsula septífraga, esférica, de coloração verde-avermelhado. O exocarpo é unisseriado; o mesocarpo parenquimático...
Palavras-chave: 2.03.00.00-0 Clusioideae; Desenvolvimento; Estrutura; Órgãos reprodutivos Botânica Clusioideae; Development; Reproductive organs; Structure.
Ano: 2010 URL: http://periodicos.uem.br/ojs/index.php/ActaSciBiolSci/article/view/3567
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Compressive strength of rice husk stabilized termite hill soil CIGR Journal
Adekola, Kehinde Adedeji.
Termite hills are described as the structure built by termite using soil in the surrounding or within the earth. The mound has extremely hard walls constructed from bits of soil cemented with saliva and baked by the sun. This research is to determine the compressive strength of termite hill soil stabilized with rice husk. The study investigated the compressive strength of 150 mm x 150 mm x 150 mm cubes made from termite hill soil and rice husk in the different mix ratio of 50:50, 60:40, 70:30, 80:20, 100:0 and was cured for 28 d with crushing the cubes at 7 d interval. The weight, bulk density and dry density of the cubes at different THS/RH mix ratio ages were determined. Test results showed that the compressive strength of the cubes increases with age...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Termite hill soil; Clay; Rice husk; Compressive strength; Cubes; Structure; Farm; Nigeria.
Ano: 2016 URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/3398
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Tectonics and paleogeography of the Marajó Basin, northern Brazil Anais da ABC (AABC)
COSTA,JOÃO B. S.; HASUI,YOCITERU; BEMERGUY,RUTH L.; SOARES-JÚNIOR,ADILSON V.; VILLEGAS,JAVIER M. C..
The Marajó Basin area presents geologic and geomorphologic features chiefly due to the Mesozoic extension and post-Miocene neotectonics. The extension event with an Early and a Late Cretaceous phases originated four sub-basins that constitutes the Marajó Basin, with a thick continental clastic sequence showing marine influence. NW and NNW normal faults and NE and ENE strike-slip faults controlled the basin geometry. The extension, related to the Equatorial Atlantic opening, propagated into the continent along crustal weakness zones of the Precambrian Tumucumaque, Amapá and Araguaia orogenic belts. The neotectonic event is a strike-slip regime which developed transtensional basins filled in by Upper Tertiary shallow marine (Pirabas Formation) and...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Marajó Basin; Structure; Evolution; Paleogeography; Geomorphology.
Ano: 2002 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652002000300013
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A structural perspective on the mechanisms of quorum sensing activation in bacteria Anais da ABC (AABC)
LIXA,CAROLINA; MUJO,AMANDA; ANOBOM,CRISTIANE D.; PINHEIRO,ANDERSON S..
Bacteria are able to synchronize the population behavior in order to regulate gene expression through a cell-to-cell communication mechanism called quorum sensing. This phenomenon involves the production, detection and the response to extracellular signaling molecules named autoinducers, which directly or indirectly regulate gene expression in a cell density-dependent manner. Quorum sensing may control a wide range of biological processes in bacteria, such as bioluminescence, virulence factor production, biofilm formation and antibiotic resistance. The autoinducers are recognized by specific receptors that can either be membrane-bound histidine kinase receptors, which work by activating cognate cytoplasmic response regulators, or cytoplasmic receptors...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Autoinducer; Bacteria; Quorum sensing; Receptor; Structure.
Ano: 2015 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652015000502189
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A supramolecular proposal of lignin structure and its relation with the wood properties Anais da ABC (AABC)
Abreu,Heber S.; Latorraca,João V.F.; Pereira,Regina P.W.; Monteiro,Maria Beatriz O.; Abreu,Fábio A.; Amparado,Kelysson F..
In spite of the great importance of cellulose the lignin is considered the second most abundant substance of the wood. However, little attention has been given it, mainly to wood properties. The lignin as well as other structural compounds (cellulose and hemicelluloses), has obviously an important role on the wood properties, probably due its composition and existent bonds. In general lignins have β-O-4 (Alkyl Aril Ether) as majoritary bond. This bond in a continued structure form big molecules with spiral conformation as virtual model. Based on this idea, lignins that have high/low β-O-4 content may have differentiated spiraled structures,suggesting different behaviors on the wood properties,which shows that the lignins (Guaicyl:Syringyl (GS)) of...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Lignin; Molecular conformation; Wood properties; Structure.
Ano: 2009 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652009000100014
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Leaf blade anatomy and ultrastructure of six Simira species (Rubiaceae) from the Atlantic Rain Forest, Brazil Biocell
Moraes,Tarsila Maria da Silva; Barros,Claudia Franca; Neto,Sebastião José da Silva; Gomes,Valdirene Moreira; Da Cunha,Maura.
Simira is a predominantly woody Neotropical genus comprising 41 taxa, 16 of which occur in Brazil and eight of them in the southeastern region of Brazil. Leaf blades of Simira eliezeriana Peixoto, S. glaziovii (K. Schum.) Steyerm., S. grazielae Peixoto, S. pikia (K. Schum.) Steyerm., S. rubra (Mart.) Steyerm., S. sampaioana (Standl.) Steyerm.were collected in the southeastern region of Brazil and fixed according to usual methods for light and electron microscopy. The leaf blades show typical characteristics of the Rubiaceae family as dorsiventral mesophyll and paracytic stomata. The presence of two bundle sheaths that extend to the upper epidermal layer, prismatic crystal and crystal-sand, alkaloids in the mesophyll and the organization micromorphological...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Leaf anatomy; Structure; Morph-anatomy.
Ano: 2009 URL: http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S0327-95452009000300004
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Pollen morphology of Oxalis species from Buenos Aires province (Argentina) Biocell
Rosenfeldt,Sonia; Galati,Beatriz G.
Pollen morphology and the degree of pollen variability within nine species and two varieties of Oxalis species from Buenos Aires Province (Argentina) were studied using light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Oxalis pollen grain is generally 3-colpate and the shape is prolate spheroidal, oblate spheroidal or spheroidal. The exine is microreticulate. The brochi are circular to polygonal; brochi sizes decrease near the colpi. The colpus membrane observed in unacetolysed material, is crustate or granular. The colpus length varies within a species; the largest grains are produced in stamens with long filaments and the smallest ones in stamens with short filaments. Four pollen types are distinguished...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Pollen; Oxalis; Morphology; Structure.
Ano: 2007 URL: http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S0327-95452007000100002
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Natural regeneration in a quaternary coastal plain in southern Brazilian Atlantic Rain forest BABT
Salimon,Cleber Ibraim; Negrelle,Raquel R. B..
Composition, structure and dynamics of an eight year old secondary forest was studied at Reserva Volta Velha (26°04'S; 48°38'W), southern Brazil. A 0.72ha plot was divided into 36 subplots of 20X10m, where all trees/shrubs greater than 1m tall were identified, measured (height/diameter) and evaluated (successional status). The results were: (1) 95 species collected within 68 genera and 44 families; the most species rich families were Myrtaceae and Asteraceae with 8 species each; (2) the most important species (considering biomass and density) were Psidium cattleianum, Eupatorium casarettoi, Ocotea pulchella and Ternstroemia brasiliensis; (3) the most similar area was a fallow abandoned 35 years ago; (4) the higher species diversity were found in border...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Atlantic Rain Forest; Floristics; Structure; Regeneration; Dynamics.
Ano: 2001 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132001000200008
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Structure and dynamics of phytoplankton community in the Botafogo reservoir-Pernambuco-Brazil BABT
Lira,Giulliari Alan da Silva Tavares de; Bittencourt-Oliveira,Maria do Carmo; Moura,Ariadne do Nascimento.
The aim of the present study was to investigate the structure and dynamics of the phytoplankton in the Botafogo reservoir-PE-Brazil. Phytoplankton assemblages were identified from current literature and density was estimated using an inverted microscope. Concurrently to the sampling of biotic variables, measurements of abiotic parameters, such as water temperature, dissolved oxygen and pH, were determined using field probes and transparency was determined with a Secchi disk. Total phosphorus and total nitrogen concentrations were determined in laboratory. A total of 24 taxa were identified. Chlorophyta presented the greatest number of species. Species diversity in the reservoir was low throughout the study period. Principal component analysis revealed that...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Structure; Tropical reservoir; Phytoplankton; Brazil.
Ano: 2009 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132009000200029
Registros recuperados: 69
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