Browsing Facultad de Ciencias Exactas y Naturales by Title
Now showing items 1625-1644 of 2613
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Investigación educativa e investigación en educación matemática
(Universidad Nacional (Costa Rica), 2013)El presente artículo teórico tiene como propósitos exponer el punto de vista de distintos autores sobre el concepto de educación; establecer la relación entre ciencias de la educación, pedagogía y ... -
Investigación y desarrollo del Sistema Gestor de Información Estadística (S.I.G.L.E.) para la Unidad de Servicios de Información y Divulgación Estadística, del Área de Estadística y Censos del Ministerio de Economía, Industria y Comercio
(Universidad Nacional (Costa Rica), 1999)El resultado más importante obtenido en la investigación, es lograr tener un programa claro del estado actual del servicios de información que el Área presta a sus usuarios, destacando los problemas y necesidades actuales ... -
Investigating the impacts of biochar on water fluxes in 2 tropical agriculture using stable isotopes
(European Geosciences Union, 2020)Amending soils with biochar, a pyrolyzed organic material, is an emerging practice to potentially increase plant available water. However, it is not clear (1) to what extent biochar amendments increase soil water storage ... -
Irbesartan desmotropes: Solid-state characterization, thermodynamic study and dissolution properties
(Xi'an Jiaotong University, 2019-07-10)Irbesartan (IBS) is a tetrazole derivative and antihypertensive drug that has two interconvertible structures, 1H- and 2H-tautomers. The difference between them lies in the protonation of the tetrazole ring. In the ... -
Iridoids from the aerial parts of Verbena littoralis (Verbenaceae)
(Elsevier, 2004)The iridoids, 6S-hydroxy-8S-methyl-4-methylene-hexahydro-cyclopenta[c]pyran-3-one and 6S,9S-dihydroxy-8S-methyl-4- methylene-hexahydro-cyclopenta[c]pyran-3-one, were isolated from the aerial parts of Verbena littoralis. ... -
Isolation and Characterization of Nanocellulose Obtained from Industrial Crop Waste Resources by Using Mild Acid Hydrolysis
(Tech Science Press, 2018)Cellulose, microcrystalline cellulose and nanocellulose were prepared from three agricultural waste resources: pineapple leaf (PALF), banana rachis (BR), and sugarcane bagasse (SCB). Each waste resource was first converted ... -
Isolation and Characterization of Nanofibrillar Cellulose from Agave tequilana Weber Bagasse
(Hindawi Limited, 2019)The bagasse of Agave tequilana Weber is one of the most abundant agroindustrial wastes in the state of Jalisco. However, at the present time, there is no technical use for this waste, and its high availability makes it ... -
Isolation and characterization of partial insulin-like androgenic gland hormone gene from distal terminal ampoules of three marine shrimp Penaeus species from the Eastern Pacific
(2018)The expansion of the shrimp industry depends on scientific advances related to the understanding of reproductive endocrinology that allows the development of aquaculture programs based on biotechnology. An insulin ... -
Isolation and partial purification of a hemolytic sphingomyelin-inhibitable fraction from the sea anemone Anthopleura nigrescens
(2014-03)Actinoporins are highly hemolytic pore-forming proteins with a molecular mass of around 20 kDa and high affinity for sphingomyelin-containing membranes. On the crude extract of the sea anemone Anthopleura nigrescens, the ... -
Isolation of ammonium- and nitrite-oxidizing bacterial strains from soil, and their potential use in the reduction of nitrogen in household waste water
(Universidad de Costa Rica, 2017-12-01)Currently, nitrogen has become the main element of water pollution, causing riverine, lacustrine and coastal eutrophication. The continuous contamination of aquifers and the absence of planned water resource utilization, ... -
Isolation on a remote island: genetic and morphological differentiation of a cosmopolitan odonate
(Nature Publishing Group, 2019-06-01)Although low levels of genetic structure are expected in highly widespread species, geographical and/or ecological factors can limit species distributions and promote population structure and morphological differentiation. ... -
Isomerization of fatty acids: A cellular barrier mechanism in nanotechnology?
(Journal of Nanoscience and Nanotechnology Vol.17 1-9, 2017-01)This work is a kinetic study of the coupling reaction of 2-mercaptoethanol with methyl undecenoate and with methyl oleate through " click " chemistry. Reversibility and reactivity of each system were followed through Fourier ... -
Isotope hydrology and baseflow geochemistry in natural and human-altered watersheds in the Inland Pacific Northwest, USA
(2015-02-18)This study presents a stable isotope hydrology and geochemical analysis in the inland Pacific Northwest (PNW) of the USA. Isotope ratios were used to estimate mean transit times (MTTs) in natural and human-altered watersheds ... -
Isotope hydrology of a tropical coffee agroforestry watershed: Seasonal and event-based analyses
(Wiley & Sons, 2018)Stable isotope variations are extremely useful for flow partitioning within the hydrologic cycle but remain poorly understood throughout the tropics, particularly in watersheds with rapidly infiltrating soils, such as ... -
Isotopic composition and major ion concentrations of national and international bottled waters in Costa Rica
(Elsevier (Países Bajos), 2021)Global bottled water consumption has largely increased (14.35 billion gallons in 2020) [1], [2], [3], [4], [5] during the last decade since consumers are demanding healthier and safer forms of rehydration. Bottled water ... -
Isotopic composition in precipitation and groundwater in the northern mountainous region of the Central Valley of Costa Rica
(Taylor & Francis, 2016)The linkage between precipitation and recharge is still poorlyunderstood in the Central America region. This study focuses onstable isotopic composition in precipitation and groundwater in the northern mountainous region ... -
Isotopic variability (δ18O, δ2 H and d-excess) during rainfall events of the north American monsoon across the Sonora River Basin, Mexico
(Elsevier Ltd, 2021)The economic activities of the Sonora strongly depend on groundwater extraction, which is generally of recent meteoric origin. Understanding the hydrological functioning in this semi-arid region, located in northwestern Mexico, ... -
Key drivers controlling stable isotope variations in daily precipitation of Costa Rica: Caribbean Sea versus Eastern Pacific Ocean moisture sources
(Elsevier, 2016)Costa Rica is located on the Central American Isthmus, which receives moisture inputs directly from the Caribbean Sea and the Eastern Pacific Ocean. This location includes unique mountainous and lowland microclimates, but ... -
Key hydrological processes in the Del Azul Creek basin, sub-humid Pampean Plain
(Elsevier B.V., 2021-02)Groundwater plays an important role in the economic development of the Chaco-Pampean Plain (Argentina), where industry, agriculture and cattle farming are the main economic activities. The 66% of the country's population ... -
Kinetics of anaerobic degradation of screened dairy manure by upflow fixed bed digesters: Effect of natural zeolite addition
(Taylor & Francis, 2009)The effect of the hydraulic retention time (HRT) on the performance of two up-flow anaerobic fixed bed digesters (UFAFBDs) packed with waste tire rubber (D1) and waste tire rubber and zeolite (D2) as micro-organism ...