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Digital.CSIC (57,310 recursos)
Repositorio institucional del Consejo Superior de Investigaciones Científicas. Digital.CSIC es un depósito de documentos digitales, cuyo objetivo es organizar, archivar, preservar y difundir en modo de acceso abierto la producción intelectual resultante de la actividad investigadora del CSIC.

(IRN) Artículos post-print

Mostrando recursos 1 - 20 de 83

1. Palaeoflood hydrology: insight into rare events and extreme flood discharges - Benito, Gerardo; Thorndycraft, V. R.
Les études paléohydrologiques permettent la reconstitution de chronologies de crue à partir des traces laissées par les sédiments de crue ou l'érosion du courant. Ces marques géologiques donnent une indication sur le niveau atteint par des crues anciennes, sur des périodes de quelques siècles à plusieurs millénaires. La datation des sédiments s'effectue à partir des matériaux présents dans les dépôts de crue (isotope 14 du carbone ou thermoluminescence de grains de minéraux). Les données paléohydrologiques peuvent ensuite être exploitées d'un point de vue probabiliste, en considérant que les événements recensés ont dépassé un ou plusieurs seuils de niveau. Les différentes...

2. Evaluation of soil biodesinfestation with crop and garden residues in the control of root-knot nematodes populations. - López-Cepero, J.; Piedra Buena, A.; Díez-Rojo, M. A.; Regalado, R.; Brito, E.; Hernández, Zulimar; Figueredo, M.; Almendros, G.; Bello, A.
Fresh crop and garden residues were applied both under laboratory conditions and in commercial greenhouse in order to asses their effect on soil nematodes populations and soil fertility. In the laboratory experiments, dosages of 5 to 20 g of cabbage residues, chicken manure, cabbage residues+chicken manure, grass+chicken manure, as well as leaves and stems of orange tree, pine tree, oleander, olive tree, palm tree and boxwood were mixed with 500 g soil having root-knot nematodes (Meloidogyne incognita) and soil moisture was adjusted at field capacity. A control treatment without residues was also included. The mixtures were kept into plastic bags,...

3. Nitrate uptake rates in freshwater plankton: the effect of food web structure - Rojo, Carmen; Rodrigo, María A.; Salazar, Guillem; Álvarez Cobelas, Miguel
Nitrate incorporation rates by primary producers and the transfer of nitrogen to upper planktonic food web levels in different seasons (spring and summer of different years) were studied using a microcosm experimental approach. The study communitieswere natural plankton communities from Colgada Lake (central Spain),which is heavily polluted by nitrate. Natural δ15N in phytoplankton and zooplankton was measured and experiments were performed on the 15N supply. Naturally derived δ15N varied from 7.4 to 8.6‰ and from 10.0 to 16.8‰ in phytoplankton and zooplankton respectively. Nitrogen incorporation rates ranged from 0.006 to 0.036μMh−1 and from 0.0004 to 0.0014μMh−1 in phytoplankton and zooplankton respectively. The differences in natural δ15N...

4. Microinvertebrate and plant beta diversity in dry soils of a semiarid agricultural wetland complex - Angeler, D. G.; Viedma, Olga; Cirujano, Santos; Álvarez Cobelas, Miguel; Sánchez Carrillo, Salvador
The relationship between environmental features and the β diversity of the propagule bank of dry soils of temporary wetlands has relevance to ecological theories of community structure and to the conservation of wetland biodiversity. The correlation of β diversity of microinvertebrates and macrophytes derived from propagules in dry soils with wetland habitat characteristics, catchment land-use, and the distance between wetlands in a remnant pond complex in central Spain was assessed. Redundancy analyses showed that β diversity of both groups correlated with habitat characteristics, whereas associations with catchment agricultural practices were weaker. Nestedness analyses showed that species-poor communities from degraded sites tended to form nested subsets of...

5. Effects of the Lipoxygenase enzyme on morphological changes of the ef face in the Plasmalemma of the Evernia Prunastri Phycobiont - Rapsch, S.; Ascaso, Carmen; Cifuentes, B.
Evernia prunastri (L.) Ach. thalli are subjected to the activity oía lipoxygenase enzyme (Linoleate : oxygen oxidoreductase, EC which usually takes place in phycobiont cells. This activity increases when exposed to light for a period of 9 hours. In such incubation conditions, the dimeric partióles on the EF face of the phycobiont plasmalemma are splitted by which the particle size is reduced while their distribution frequency increases.

6. Laser Flash-Induced Photoreduction of Photosynthetic Ferredoxins and Flavodoxin By 5-Deazariboflavin and by a Viologen Analogue - Navarro, José A.; Hervás, Manuel; Pueyo, José J.; Medina, Milagros; Gómez-Moreno, Carlos; Rosa, Miguel A. de la; Tollin, Gordon
Lase flash photolysis has been used to compare the kinetics of reduction of ferredoxin isoforms from the green alga Monoraphidium braunii, and the ferredoxin and flavodixin from the cyanobacterium Anabaena PCC7119, by 5-deazariboflavin semiquinone ((dRfH)

7. The effect of desiccation on Pyrenoid structure in the Oceanic lichen Parmelia Laevigata - Brown, D. H.; Ascaso, Carmen; Rapsch, S.
Phycobiont cells of Parmelia laemgata contain chloroplasts with pyrenoids penetrated by a reticulum of tubules. The occurrence and significance of such tubules in algae is discussed. Although these tubules collapsed in desiccated cells, their lumen reappeared on rehydration. However, in such desiccated cells, pyrenoglobuli did not become peripherally located within the pyrenoid, except when damage occurred to the pyrenoid matrix. Rehydration of desiccated cells reduced the number of pyrenoglobuli per pyrenoid.

8. Bioconstructions in ochreous speleothems from lava tubes on Terceira Island (Azores) - Ríos, Asunción de los; Bustillo, Mª Ángeles; Ascaso, Carmen; Carvalho, M. R.
The ochreous speleothems examined here were obtained from a lava tube on Terceira Island (Azores) and show compact mineralized areas intermixed with zones in which bacterial structures are evident. Bacterial layers of filament-like structures are common throughout the deposits but differences in microstructure among the different speleothems were observed, reflecting a broad morphological range of deposits. The structures and minerals detected in the speleothems betray their biogenic origin. Gallionella and Leptothrix were the two most frequently observed morphotypes and probably the main contributors to speleothem formation. However, DGGE analysis indicated the presence of another bacterial population (with a predominance of proteobacteria) that could also contribute to iron...

9. Impactos sobre los ecosistemas terrestres - Valladares, Fernando; Peñuelas, J.; Luis Calabuig, E. de
España presenta una gran variedad de ecosistemas terrestres, muchos de ellos únicos y todos ellos proporcionando un amplio número de bienes y servicios. Estos ecosistemas han estado sometidos a intensos cambios climáticos en el pasado pero el ritmo de estos cambios se ha acelerado de forma excepcional. El cambio climático acelerado está dando lugar a un abanico de efectos directos e indirectos que se ven acentuados por la interacción con otros motores del cambio global (cambios de uso del territorio, contaminación, intercambio biótico). Los efectos difieren para los ecosistemas de la región Atlántica, limitados por temperatura, y para los de la región Mediterránea, limitados por agua. Mientras...

10. Action of humic Acid Preparations on Leaf Development, Mineral Elements Contents and Chloroplast Ultrastructure of Ryegrass Plants - Fortun, C.; Rapsch, S.; Ascaso, Carmen
The action of humic acid preparations obtained from straw or peal fermented under controlled conditions on mineral elements contents, área and dimensions of leaves, and ultrastructure of chloroplasts of Lolium perenne L. plants was studied. The naturally fermented organic materials were the source of most effective humic acid preparations. Quantitative transmission electrón microscopy indicated that the treatment of Lolium plants with humic acid from peal incubated without additives induced the most important increase of photosynthetic structures.

11. Chloroplast Crystalloids and Other Alterations in Response to Lichen Substances - Ascaso, Carmen; Orus, I.; Estévez, P.
Many lichen phenolics act as allelopathic substances, lowering germination and growth rates of higher plants or even promoting their decay. Physiological observations previously made on the effect of Evernia prunastri (L.) Ach. lichen compounds on Quercus rotundifolia Lam. explants were correlated in this work with the ultrastructural alterations in chloroplasts. The degenerative changes included the swelling and collapse of granal and agranal thylakoids, with a peripheric display of lamellae and an increase in the number and size of plastoglobuli, though not as high as described elsewhere. Besides these eífects, that are in line with the pattern of breakdown of chloroplasts of leaves senescing under natural conditions, bundles...

12. The pedogenic action of Parmelia Conspersa, Rhizocarpon Geographicum and Unbilicaria Pustulata - Ascaso, Carmen; Galvan, J.; Ortega, C.
The weathering of rock surfaces and soil formation are the result of two clearly distinguished processes, cheluviation and soluviation (Swindale & Jackson, 1956). In the presence of chelating agents, minerals are decomposed and then eluviated (Schatz et al., 1954; Schatz, 1963). Lichens excrete various compounds the solubility of which has generally been discounted (Smith, 1921; Hale, 1961; Smith, 1962; Haynes, 1964). However, more recent studies have shown that at least certain lichen substances, namely depsides and depsidones, are in fact slightly soluble in water (Iskandar and Syers, 1971) and that the presence of electrón donor groups in their respective molecules (Ginzburg et al., 1963; Kononova et al., 1964)...

13. Ultrastructural modifications in Lichens induced by environmental humidity - Ascaso, Carmen
Ultrastructural studies of lichens have not paralleled investigations on lichen physiology and, with one exception (Harris and Kershaw, 1971), morphological changes have not been studied under controlled environmental conditions. Moreover, contradictory results on the same topic have been published. For example, Brown and Wilson (1968) and Jacobs and Ahmadjian (1971a) claimed that under damp conditions lichen thalli frequently contained starch inclusions, whereas other results (Harris and Kershaw, 1971; Ascaso and Calvan, 1976) conflicted with this observation. According to Webber and Webber (1970), starch granules do not appear in wet thalli collected in the spring because of the increased metabolic requirement of the mycobiont. The pyrenoid of green phycobionts usually contains...

14. The ultrastructure of the phycobiont of dessiccated and hydrated lichens - Ascaso, Carmen; Brown, D. H.; Rapsch, S.
Observations have been made on the effects of different storage treatments, either 100% or 0% r.h., 12 h light:12 h dark or 24 h dark for 2 days, ort the ultrastructure of the phycobionts of Lobaria amplissima and Lasallia pustulata. After storage, Myrmecia, in the more desiccation-sensitive lichen L. amplissima, showed an increased number of cytoplasmic storage bodies which had more frequently dark contents and a half-moon-like appearance. Trebouxia, from the desiccation-resistant L. pustulata, showed major cellular disorganization when stored at 100% r.h. in the light: dark regime, whereas, in the dark, reorganization of thylakoids into a parallel arrangement occurred. Treatment at 0% r.h. in the light:dark regime induced...

15. Seasonal nitrogen dynamics in a seepage lake receiving - Piña, Elisa; Álvarez Cobelas, Miguel
Studies on nitrogen dynamics in seepage lakes are seldom undertaken, yet our understanding of the complex pattern of the nitrogen (N) cycle is complicated by its temporal and spatial heterogeneity. This research investigated temporal variation inNconcentration, considering different forms ofN(NO−3 ,NO−2 ,NH+4 , dissolved organicN, particulate organic N) in a Spanish flowthrough seepage lake (Colgada Lake) receiving high N loads. The study was based on monthly data collected over the period 2003–2005 from lake inputs and outputs, vertical profiles at a single representative site in the middle of the lake and fluxes of NH+4 and NO−3 at the sediment–water interface. The distribution of total N...

16. Germinación y efecto de las bajas temperaturas sobra la nascencia, supervivencia y desarrollo del trébol subterráneo - Mendizabal, Teresa; Pastor Piñeiro, Jesús; Martín, Amalia; Oliver, Salvador
Con el fin de conocer la influencia de los factores ambientales sobre la germinación y diferentes fases del ciclo de desarrollo del trébol subterráneo en un lugar de clima mediterráneo extremado (Madrid), se ha trabajado con siete cultivares australianos y ocho poblaciones autóctonas. En las pruebas de germinación, las poblaciones españolas dieron porcentajes comprendidos entre el 31 y el 82 %. No se encontró diferencia apreciable en los porcentajes de germinación con la edad de la semilla a los dos años de su maduración. Se obtuvieron también los porcentajes de semillas germinadas después de sometidas a un proceso de escarificación, que hacemos sinónimas de «semillas duras»; cinco de las ocho poblaciones...

17. Impact of Municipal Waste on Mediterranean Dry Environments - Pastor Piñeiro, Jesús; Urcelay, A.; Oliver, Salvador; Hernández, A. J.
We studied yhe physical characteristics and the main chemical components found in sealed municipal landfills in semi-arid environments.

18. Los pastos xerofíticos de la montaña de Teruel y factores que influyen en su variación - Gómez Sal, A.; Pastor Piñeiro, Jesús; Oliver, Salvador
Se analizan las relaciones dinámicas existentes entre la composición florística de los pastos xerofíticos y los distintos factores edafoclimáticos que los condicionan. El estudio de la relación entre las especies y los estados de los diferentes factores, efectuado mediante el análisis factorial de correspondencias, permite definir grupos de especies representativos de los principales tipos de pasto, destacando los nexos existentes entre grupos de especies y grupos de estados. Este procedimiento, de carácter global, se complementa con otro de carácter analítico (perfiles ecológicos) que resalta la cuantía y nivel de significación de la relación de cada especie con cada estado. De los tres grupos observados, el primero, «pastos de loma» se ve afectado por...

19. Incidencia fitoedáfica de uso ganadero en un antiguo sistema cerealista - Pastor Piñeiro, Jesús; Hernández, A. J.; Estalrich, E.; Urcelay, A.
El cese de un cultivo, dedicado durante muchos años a la rotación de cebada-veza, en un suelo cerealista de secano representativo, perteneciente a la Comunidad de Castilla- La Mancha, en el que se propició por un lado la recuperación de la vegetación natural y por otro se sometió a un pastoreo itinerante con ovino, comenzó a poner ya de manifiesto al cabo de pocos años la variación experimentada en las condiciones físicas y químicas del suelo así como la variación del número de especies y el recubrimiento de las mismas. Así, la densidad aparente y la estabilidad estructural del suelo se incrementaron especialmente en la zona pastada....

20. Especies espontáneas anuales del género Trifolium en la zona Centro de España - Martín, Amalia; Morey, Miguel; Oliver, Salvador
Se da una panorámica de la distribución de las especies anuales del género Trifolium en la zona Centro de España, en relación con altitud, subregiones fitoclimáticas y factores edáficos (pH y contenido en carbonatas}. Las especies T. strictum y T. dubium, que se encuentran por encima de los 900 m. de altitud (900-1.500 m.) y en la subregión fitoclimática IV (VI), muestran marcadas preferencias por suelos ácidos. Las especies T. striatum y T. smyrnaeum, que se encuentran abundantemente repartidas por encima de los 900 m. de altitud y difundidas por las tres subregiones fitoclimáticas consideradas, también muestran marcadas preferencias por sucios ácidos. Las especies T. scabrum, T. tomentosum, T. cherleri y...

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