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Historia del uso reciente de tierras de las sabanas de américa del sur. Estudios de casos en sabanas del orinoco
López-Hernández,Danilo; Hernández-Hernández,Rosa Mary; Brossard,Michel;
Interciencia , 2005,
Abstract: south american savannahs cover a surface of 269×106ha in brazil, colombia, venezuela, guyana and bolivia. in a world scale savannahs are one of the most important land extensions with agricultural potential for crop and forestry production. these territories also constitute the main alternative to agricultural expansion into ecologically fragile tropical areas such as tropical rainforests and hillsides. forty years ago anthropic activity had little effect on latin american savannahs, since they were used for extensive cattle raising. in the last four decades, however, the natural herbaceous vegetation with low nutrient requirements in the savannahs (llanos) of colombia and venezuela, as well as in the cerrado (brazil) has been replaced by introduced african pastures, particularly from the genera brachiaria and andropogon. furthermore, intensive reforestation programs for timber and pulpwood commercialization have introduced species able to cope with the environmental conditions, such as pinus and eucaliptus. the introduction of african pastures and annual and perennial crops has been possible with fertilization (n, p, k and lime). the landscape modifications caused by these land uses are usually far from the urban areas and are still considered to be low. however, if the entire land surface currently affected by agriculture and agroforestry use and the land yet to be incorporated into projects is taken into consideration, a profound modification is expected to occur in these biomes. herein is presented a preliminary comparative review of the agricultural colonization processes in the llanos and cerrados. in the need to generate indicators related to biogeochemical processes, three case studies from venezuelan savannahs are presented.
Spatial variability of soil phosphorus of a low productivity Brachiaria brizantha pasture
Corazza, Edemar Joaquim;Brossard, Michel;MuraokaI, Takashi;Coelho Filho, Maurício Antonio;
Scientia Agricola , 2003, DOI: 10.1590/S0103-90162003000300022
Abstract: studies on soil phosphorus (p) of low productivity cultivated pastures in cerrado (brazilian savanna) areas and surveys on other possible problems related to p are scarce. the spatial variability of soil phosphorus content of a rhodic ferralsol was studied in a low productivity pasture of brachiaria brizantha (bb) grown for 10 years, without fertilizer application, in an experimental area at planaltina (go), brazil. soil samplings were performed on a regular grid of 10 by 10 meters, with 98 sampling points before (between tussocks and under tussocks) and after the establishment of the experiment (after fertilizing). on the same grid, forage plants were collected and separated into fractions for n and p content analyses. soil available phosphate was determined by the resin method (pr) and complemented by the 32p isotopic exchange kinetics analysis. descriptive statistical and geostatistical analyses were utilized to describe the spatial variability. the pr content on soil samples under tussocks presented mean and median values 45% larger than in soil samples taken between tussocks. the higher variation is probably related to the greater concentration of bb roots, soil organic matter content and soil p recycled through the plants tussocks. the spatial variability of pr in this soil was high especially after fertilizer application. this variable did not present spatial dependence for the regular 10 m sampling. the generated knowledge on p variability of soils under low productivity cultivated pastures revealed problems related to the sampling methodology traditionally utilized and to p application.
Spatial variability of soil phosphorus of a low productivity Brachiaria brizantha pasture
Corazza Edemar Joaquim,Brossard Michel,MuraokaI Takashi,Coelho Filho Maurício Antonio
Scientia Agricola , 2003,
Abstract: Studies on soil phosphorus (P) of low productivity cultivated pastures in Cerrado (Brazilian Savanna) areas and surveys on other possible problems related to P are scarce. The spatial variability of soil phosphorus content of a Rhodic Ferralsol was studied in a low productivity pasture of Brachiaria brizantha (BB) grown for 10 years, without fertilizer application, in an experimental area at Planaltina (GO), Brazil. Soil samplings were performed on a regular grid of 10 by 10 meters, with 98 sampling points before (between tussocks and under tussocks) and after the establishment of the experiment (after fertilizing). On the same grid, forage plants were collected and separated into fractions for N and P content analyses. Soil available phosphate was determined by the resin method (Pr) and complemented by the 32P isotopic exchange kinetics analysis. Descriptive statistical and geostatistical analyses were utilized to describe the spatial variability. The Pr content on soil samples under tussocks presented mean and median values 45% larger than in soil samples taken between tussocks. The higher variation is probably related to the greater concentration of BB roots, soil organic matter content and soil P recycled through the plants tussocks. The spatial variability of Pr in this soil was high especially after fertilizer application. This variable did not present spatial dependence for the regular 10 m sampling. The generated knowledge on P variability of soils under low productivity cultivated pastures revealed problems related to the sampling methodology traditionally utilized and to P application.
Marion Coddington Bromley (1912-1996) : une militante pacifiste radicale féministe, master 2 d’histoire contemporaine, ENS Lyon (dir. Romain Huret, Université Lyon 2)
Doris Brossard
Genre & Histoire , 2012,
Abstract: Née à en 1912 à Akron dans l’état de l’Ohio, Marion Coddington s’engage dans la cause pacifiste dans les années 1930 au sein d’une organisation locale, l’Akron Council for Peace Action. Au début des années 1940, elle quitte sa région natale pour s’installer à New York où elle travaille à plein temps pour la Fellowship of Reconciliation (FOR), organisation pacifiste chrétienne créée en 1915. Elle y développe alors un pacifisme centré sur l’individu et sur la recherche d’une société juste et é...
La production des paysages au Svalbard
Thierry BROSSARD
Mappemonde , 1987,
Abstract:
Política poética
Nicole Brossard
Ilha do Desterro , 2010,
Abstract: Um dos primeiros ensaios que Brossard escreveu em inglês, "Política Poética" inicialmente surgiu em 1990, em The Politics of Poetic Form: Poetry and Public Policy, organizado pelo poeta americano Charles Bernstein. O ensaio também consta na coletanea de ensaios de Brossard, Fluid Arguments (Mercury Press, 2005). Nele, Brossard aborda o que chama de "corpo da escrita, suas motiva es, sua energias" como também a "rea o lingüística" exigida quando um escritor luta com e contra seu contexto sócio-econ mico, quando "discorda" dele. Esse ensaio cria e participa em um discurso de resistência no sentido mais fundamental, na medida em que descreve n o só como parece ou se sente um discurso de resistência, mas como um escritor inovador abre espa o para diferentes quest es, corpos e "posturas" na linguagem.
Ixodes ricinus Tick Lipocalins: Identification, Cloning, Phylogenetic Analysis and Biochemical Characterization
Jér?me Beaufays, Beno?t Adam, Yves Decrem, Pierre-Paul Prév?t, Sébastien Santini, Robert Brasseur, Michel Brossard, Laurence Lins, Luc Vanhamme, Edmond Godfroid
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0003941
Abstract: Background During their blood meal, ticks secrete a wide variety of proteins that interfere with their host's defense mechanisms. Among these proteins, lipocalins play a major role in the modulation of the inflammatory response. Methodology/Principal Findings Screening a cDNA library in association with RT-PCR and RACE methodologies allowed us to identify 14 new lipocalin genes in the salivary glands of the Ixodes ricinus hard tick. A computational in-depth structural analysis confirmed that LIRs belong to the lipocalin family. These proteins were called LIR for “Lipocalin from I. ricinus” and numbered from 1 to 14 (LIR1 to LIR14). According to their percentage identity/similarity, LIR proteins may be assigned to 6 distinct phylogenetic groups. The mature proteins have calculated pM and pI varying from 21.8 kDa to 37.2 kDa and from 4.45 to 9.57 respectively. In a western blot analysis, all recombinant LIRs appeared as a series of thin bands at 50–70 kDa, suggesting extensive glycosylation, which was experimentally confirmed by treatment with N-glycosidase F. In addition, the in vivo expression analysis of LIRs in I. ricinus, examined by RT-PCR, showed homogeneous expression profiles for certain phylogenetic groups and relatively heterogeneous profiles for other groups. Finally, we demonstrated that LIR6 codes for a protein that specifically binds leukotriene B4. Conclusions/Significance This work confirms that, regarding their biochemical properties, expression profile, and sequence signature, lipocalins in Ixodes hard tick genus, and more specifically in the Ixodes ricinus species, are segregated into distinct phylogenetic groups suggesting potential distinct function. This was particularly demonstrated by the ability of LIR6 to scavenge leukotriene B4. The other LIRs did not bind any of the ligands tested, such as 5-hydroxytryptamine, ADP, norepinephrine, platelet activating factor, prostaglandins D2 and E2, and finally leukotrienes B4 and C4.
Incidence of epigeal nest-building termites in Brachiaria pastures in the Cerrado
Oliveira, Maria Inês Lopes de;Brunet, Didier;Mitja, Danielle;Cardoso, Wellington dos Santos;Benito, Norton Pólo;Guimar?es, Maria de Fátima;Brossard, Michel;
Acta Scientiarum. Agronomy , 2011, DOI: 10.4025/actasciagron.v33i1.7075
Abstract: this study aimed to determine the number of termite epigeal nests and estimate the soil turning capacity of termites in cultivated pasture environments and in a native vegetation area. surveys were conducted in four areas: three pasture areas and a cerrado area, measuring 5 ha each. for each nest, the height, the perimeter and diameter at the base were measured. the volume of each mound was calculated. turned soil was determined by randomly sampling 30 termite mounds in a pasture area for bulk density determinations. the mean number of termite mounds per ha was 408; the highest number of termite nests (672 per ha) was found in the 10-year-old pasture. in terms of termite mound density, there was no difference between the cerrado, 3-year-old pasture, and 3-year-old intercropped pasture treatments. the total area occupied by termite nests ranged from 0.4 to 1.0%. the mean bulk density of the nest materials was 1.05 g cm-3. the total nests volume ranged from 4 to 11 m3 ha-1. the total mass of the soil turned by the termites ranged from 3.4 to 13.4 ton. ha-1.
Seasonal variability of benthic ammonium release in the surface sediments of the Gulf of Gdansk (southern Baltic Sea)
Dorota Maksymowska-Brossard
Oceanologia , 2001,
Abstract: This paper describes the seasonal and spatial variations of diffusive sediment- water ammonium fluxes in the western part of the Gulf of Gdansk (southern Baltic). It assesses the potential environmental controls of these fluxes, such as the inflow of organic matter to bottom sediments and its quality, temperature-induced degradation of organic matter, and the redox potential of sediments. Ammonium fluxes, calculated using Fick's first law, were always in the direction from the sediment into the water column and differed significantly with respect to sediment type. Fluxes were most intensive in sediments with the highest silt-clay fraction located in the deepest parts of the study area. The mean annual diffusive fluxes of ammonium from sediments to near-bottom water were estimated at 5.24 tonnes km-2 year-1 for silty-clays, 1.85 tonnes km-2 year-1 for silty-sands and 1.03 tonnes km-2 year-1 for sandy sediments. There was a high seasonal variation, with the greatest ammonium release in summer and early autumn, when the temperature of near-bottom water was the highest. On the basis of the calculated diffusive ammonium fluxes, we estimated that approximately 2700 tonnes of N-NH4+ are released annually from the surface sediments of the western part of the Gulf of Gdansk, providing a minimum of 10% of the mineral nitrogen essential for primary production in surface waters. Our results are undoubtedly underestimated, as we disregarded advective ammonium fluxes, which in some areas of the Gulf of Gdansk could well be comparable to diffusive fluxes.
Cha?nes de Markov Constructives Indexées par Z
Jean Brossard,Christophe Leuridan
Mathematics , 2007, DOI: 10.1214/009117906000000430
Abstract: Nous \'{e}tudions les cha\^{{\i}}nes de Markov $(X_n)_{n\in\mathbf{Z}}$ gouvern\'{e}es par une relation de r\'{e}currence de la forme $X_{n+1}=f(X_n,V_{n+1})$, o\`{u} $(V_n)_{n\in\mathbf{Z}}$ est une suite de variables al\'{e}atoires ind\'{e}pendantes et de m\^{e}me loi telle pour tout $n\in \mathbf{Z}$, $V_{n+1}$ est ind\'{e}pendante de la suite $((X_k,V_k))_{k\le n}$. L'objet de l'article est de donner une condition n\'{e}cessaire et suffisante pour que les innovations $(V_n)_{n\in\mathbf{Z}}$ d\'{e}terminent compl\`{e}tement la suite $(X_n)_{n\in \mathbf{Z}}$ et de d\'{e}crire l'information manquante dans le cas contraire.
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