oalib

OALib Journal期刊

ISSN: 2333-9721

费用:99美元

投稿

时间不限

2017 ( 110 )

2016 ( 257 )

2015 ( 5201 )

2014 ( 6101 )

自定义范围…

匹配条件: “Gutiérrez V” ,找到相关结果约135834条。
列表显示的所有文章,均可免费获取
第1页/共135834条
每页显示
The Scientific Development of the Physiology of Plants in the American Tropics
V. Gutiérrez,Marco;
Revista de Biología Tropical , 2002,
Abstract: this paper is a research and journalistic work that summarizes and synthesizes the scientific development of the physiology of plants in the american tropics, also known as the neotropics. it contains the contributions of numerous biologists interested in the physiology of tropical plants. the fabulous structural and functional diversity of tropical forests is still the major driver of research in this field. classical physiological work involving tropical plants, such as the discovery of c4 photosynthesis in sugarcane, is invoked to exemplify the historical and current importance of physiological research in the tropics, and its applications in agriculture, forestry and conservation. an historical background describing the early and more recent development of a tradition on the physiological study of tropical plants is followed by a summary of the research conducted on the physiology of tropical crops. common areas of interest and influence between the fields of crop physiology and plant ecophysiology are identified and exemplified with problems on the environmental physiology of crops like coffee and cassava. the physiology of tropical forest plants is discussed in terms of its contributions to general plant physiological knowledge in areas such as photosynthetic metabolism and plant water relations. despite the impressive technical advances achieved during the past decade, the importance of continuous development of appropriate instrumentation to study and measure the physiology of plants in situ is stressed. although the basic metabolic processes that underlie the mechanisms of plant responses to the environment are probably highly conserved and qualitatively similar among tropical and temperate plants, it is also apparent that tropical plants exhibit metabolic peculiarities. these include aspects of photosynthetic metabolism, phloem transport physiology, sensitivity to low temperatures, reproduction, responses to climatic seasonality, and a large variety of bio
Figuras del sujeto
Gutiérrez V., Daniel
Iconos : Revista de Ciencias Sociales , 2002,
Abstract:
The Scientific Development of the Physiology of Plants in the American Tropics
Marco V. Gutiérrez
Revista de Biología Tropical , 2002,
Abstract: This paper is a research and journalistic work that summarizes and synthesizes the scientific development of the physiology of plants in the American tropics, also known as the Neotropics. It contains the contributions of numerous biologists interested in the physiology of tropical plants. The fabulous structural and functional diversity of tropical forests is still the major driver of research in this field. Classical physiological work involving tropical plants, such as the discovery of C4 photosynthesis in sugarcane, is invoked to exemplify the historical and current importance of physiological research in the tropics, and its applications in agriculture, forestry and conservation. An historical background describing the early and more recent development of a tradition on the physiological study of tropical plants is followed by a summary of the research conducted on the physiology of tropical crops. Common areas of interest and influence between the fields of crop physiology and plant ecophysiology are identified and exemplified with problems on the environmental physiology of crops like coffee and cassava. The physiology of tropical forest plants is discussed in terms of its contributions to general plant physiological knowledge in areas such as photosynthetic metabolism and plant water relations. Despite the impressive technical advances achieved during the past decade, the importance of continuous development of appropriate instrumentation to study and measure the physiology of plants in situ is stressed. Although the basic metabolic processes that underlie the mechanisms of plant responses to the environment are probably highly conserved and qualitatively similar among tropical and temperate plants, it is also apparent that tropical plants exhibit metabolic peculiarities. These include aspects of photosynthetic metabolism, phloem transport physiology, sensitivity to low temperatures, reproduction, responses to climatic seasonality, and a large variety of biotic interactions. Old and new paradigms are examined in light of recent evidence and comparative studies, and the conceptual and technical advances needed to foster the development of tropical plant ecophysiology are identified
CARTAS AL DIRECTOR
José Véliz Gutiérrez
Revista de Ciencias M??dicas de Pinar del R?-o , 2010,
Abstract:
Distance-dependent coherent charge transport in DNA: crossover from tunneling to free propagation  [PDF]
Natallia V. Grib, Dmitry A. Ryndyk, Rafael Gutiérrez, Gianaurelio Cuniberti
Journal of Biophysical Chemistry (JBPC) , 2010, DOI: 10.4236/jbpc.2010.12010
Abstract: Using a tight-binding model, we investigate the influence of intra- and interstand coupling parameters on the charge transport properties in a G-(T)j-GGG DNA sequence and its (G:C)-(T:A)j-(G:C)3 duplex attached to four electrodes. Dependences of the transmission function and of the corresponding conductance of the system on the number of bridging sites were obtained. Simulation results of a recently proposed two-strand superexchange (tunneling) model were reproduced and extended. It is demonstrated that the crossover from strong to weak distance-dependent charge transport is elucidated by a transition from under-barrier tunneling mechanism to free over-barrier propagation in the coherent regime, controlled by temperature and coupling parameters. The role of DNA- electrode coupling has been also considered. It was found that an asymmetry in the DNA-electrode coupling has a drastic effect on the con-ductance leading to an increase in delocaliza-tion of the electronic states in the DNA duplex.
Valoración de la garantía de pensión en las cuentas de ahorro individual en Colombia
Restrepo,José V; Gutiérrez,Juan C;
Innovar , 2011,
Abstract: the behavior of the individual as a person who contributes, and as the future beneficiary of a pension, is a determining factor to quantify the effects that his or her density has on the individual savings system and on the ability to demand the different guarantees. that is why the objective of this work is to seek a view based on personal finance other than what has been presented in different studies in this field carried out not only in colombia but at the international level, and to provide an approach to a solution for the problem of sustainability in retirement. to calculate the magnitude of the guarantees, a procedure was developed that combines stochastic models with diffuse logic models and actuarial estimates. in this way, and supported by results from other studies, it was possible to determine the individual savings potential that could be achieved by each individual in terms of their gender and salary cohort and the possible existing deficit for achieving a minimum retirement pension. the findings show that, under the conditions of low density of contributions, it is very difficult for the lower and middle income cohorts to be able to ensure a minimum pension without exhausting existing guarantees and without government participation.
A Comparison of Sap Flow Measurements and Potometry in Two Tropical Lowland Tree Species with Contrasting Wood Properties
Gutiérrez,Marco V; Santiago,Louis S;
Revista de Biología Tropical , 2006,
Abstract: we evaluated the performance of the heat dissipation technique (hdt) to measure sap flow in whole trees by comparison with potometric water uptake. two tropical lowland species, ochroma lagopus (balsa), a pioneer species with light wood and hyeronima alchorneoides (pilón), a late-successional species with hard wood were examined. diurnal courses of sap flow measured with the hdt showed good agreement with potometry. at the low sap flow rates (below 1 kg h-1) occurring during nocturnal recharge hdt consistently underestimated sap flow rates. this resulted in the failure of the current version of the hdt to measure nocturnal water uptake, an important component of the water budget of at least one of the two species examined. rev. biol. trop. 54(1): 73-81. epub 2006 mar 31.
La producción científica necesaria de la Universidad
José A Véliz Gutiérrez
Revista de Ciencias M??dicas de Pinar del R?-o , 2011,
Abstract:
A Comparison of Sap Flow Measurements and Potometry in Two Tropical Lowland Tree Species with Contrasting Wood Properties
Marco V Gutiérrez,Louis S Santiago
Revista de Biología Tropical , 2006,
Abstract: We evaluated the performance of the Heat Dissipation Technique (HDT) to measure sap flow in whole trees by comparison with potometric water uptake. Two tropical lowland species, Ochroma lagopus (balsa), a pioneer species with light wood and Hyeronima alchorneoides (pilón), a late-successional species with hard wood were examined. Diurnal courses of sap flow measured with the HDT showed good agreement with potometry. At the low sap flow rates (below 1 Kg h-1) occurring during nocturnal recharge HDT consistently underestimated sap flow rates. This resulted in the failure of the current version of the HDT to measure nocturnal water uptake, an important component of the water budget of at least one of the two species examined. Rev. Biol. Trop. 54(1): 73-81. Epub 2006 Mar 31.
Crecimiento de nueve especies de palmas ornamentales cultivadas bajo un gradiente de sombra
Marco V. Gutiérrez,Kenneth Jiménez
Agronomía Costarricense , 2007,
Abstract: Se evaluó el crecimiento de 9 especies de palmas cultivadas bajo un gradiente de sombra producido por mallas de polipropileno negro de 40, 50, 60, 70 y 80% de sombra, más un tratamiento de malla aluminizada de 70%, y uno con plantas a pleno sol. Las especies evaluadas fueron Caryota mitis (cola de pez), Chamaedorea costaricana (pacaya), Chamaedorea tepejilote (tepejilote), Dypsis lutescens (areca), Licuala elegans (licuala), Phoenix roebelenii (fénix), Ptychosperma macarthurii (palma macarthur), Roystonea regia (palma real), y Veitchia merrillii (navide a). Se midió la altura de las plantas, la longitud de las hojas maduras, y el número de hojas cosechadas, durante 5 cosechas por 2 a os. En general, la altura de las plantas y la longitud de las hojas fueron menores a 0-40% de sombra, se incrementaron a 50-70%, y decrecieron a 80%. C. mitis, C. tepejilote, L. elegans y P. macarthurii, se comportaron como especies obligadas de sombra y no sobrevivieron a pleno sol. C. costaricana y D. lutescens sobrevivieron a plena exposición solar, y su crecimiento alcanzó valores máximos a 50-60%. P. roebelenii, R. regia, y V. merrillii mostraron un crecimiento reducido a 0-40%, pero éste mejoró bajo los demás niveles de sombra a lo largo del gradiente. En general, 1-2 a os es un periodo apropiado para el cultivo de palmas de crecimiento rápido (R. regia, Chamedorea spp., D. lutescens) en casas de mallas. Palmas de lento crecimiento (L.elegans) pueden permanecer 3-5 a os en una casa de sombra. Se discute estrategias para el uso de gradientes de sombra en el tiempo y en el espacio, según la utilidad y los requerimientos de las especies, los requisitos establecidos por el mercado, y el ciclo de producción del material vegetal.
第1页/共135834条
每页显示


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.