排序方式： 共有18条查询结果，搜索用时 31 毫秒
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A. Tejado G. Kortaberria C. Peña J. Labidi J.M. Echeverria I. Mondragon 《Industrial Crops and Products》2008,27(2):208-213
This work proposes the use of a diisocyanate as curing agent for novolac-type lignin–phenol–formaldehyde (LPF) resins, instead of typical hexamethylene–tetraamine (HMTA), with the aim of overcoming the loss of reactivity of lignophenolic resins resulting from the introduction of lignin. Curing LPF resins with methylene–diisocyanate (MDI) and HMTA has been investigated through Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and rheological analysis. The analysis of experimental results shows that the proposed curing reaction with MDI gives similar results to those for HMTA-cured systems. However, MDI curing is faster than HMTA one and proceeds easier at lower temperatures. 相似文献
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A backcrossing programme was carried out both to assess the stability of a cytoplasmic male‐sterility (CMS) source from Helianthus resinosus, designated RES1, and to incorporate it into inbred sunflower lines (HA89, RHA271, RHA801). All the progenies, grown in different environments, were completely male‐sterile. This suggests that the expression of this cytoplasm is stable. Female‐fertility of lines HA89, RHA271 and RHA801 carrying CMS RES1 were compared with those of the corresponding fertile inbred lines. There were no differences in the number of seeds per head. This indicates that female‐fertility is not affected by RES1 cytoplasm. Cytological studies showed that meiosis proceeds normally until the tetrad stage; consequently, the absence of pollen is caused by alterations that take place during postmeiotic stages. With the aim of identifying male‐fertility restorer genotypes, crosses were made between HA89 (CMS RES1) plants and different annual diploid and perennial hexaploid Helianthus species. All the diploid germplasm evaluated behaved as a CMS RES1 maintainer. However, the hexaploid species, H. resinosus, H. x laetiflorus, H. pauciflorus and H. tuberosus, restored pollen fertility in CMS RES1 plants. 相似文献
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Darwich L Cabezón O Echeverria I Pabón M Marco I Molina-López R Alarcia-Alejos O López-Gatius F Lavín S Almería S 《Veterinary parasitology》2012,183(3-4):377-381
Toxoplasma gondii infections are prevalent in many avian species and can cause mortality in some bird hosts. Although T. gondii has been isolated from various species of birds, the role of many different species of wild birds in the epidemiology of T. gondii remains unknown. Neospora caninum, a closely related parasite to T. gondii, has been recently confirmed to infect domestic chickens and wild birds such as house sparrows (Passer domesticus). The present study reports the presence of T. gondii and N. caninum DNA by PCR in brain tissues of 14 species of wild birds from Spain. From a total of 200 samples analyzed, 12 samples (6%) were positive for T. gondii [5 Eurasian jays (Garrulus glandarius), 5 magpies (Pica pica), 1 black kite (Milvus migrans) and 1 Griffon vulture (Gyps fulvus)], while 3 samples (1.5%) were positive for N. caninum [2 magpies and 1 common buzzard (Buteo buteo)]. This is the first report of detection of T. gondii in magpies, griffon vulture and black kite and of N. caninum in common buzzard and magpies, extending the list of natural intermediate hosts for T. gondii and N. caninum infections to these species. 相似文献
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Ecology. Managing water for people and nature 总被引：1，自引：0，他引：1
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Land use change and ecosystem services provision: a case study of recreation and ecotourism opportunities in southern Chile 总被引：1，自引：0，他引：1
Land use and cover change (LUCC) is among the most important factors affecting ecosystem services. This study examines the influence of LUCC on recreation and ecotourism opportunities over three decades in southern Chile. An in-depth analysis of the transition matrix was conducted based on Landsat images from 1976, 1985, 1999 and 2007. Main LUCC trajectories were linked to two ecosystem service indicators: (i) Recreation and ecotourism potential, measured in a 0–100 point scale; and (ii) Recreation and ecotourism opportunities, measured in visitors/ha. A total of 900 trajectories occurred in the landscape between 1976 and 2007. The most important trajectories in terms of area, were the recent degradation of old-growth to secondary forest between 1999 and 2007 (23,290 ha; 13.5 % of landscape), and the early clearing of shrublands for agriculture and pasture land between 1976 and 1985 (7,187 ha, 4.2 % of landscape). In turn, the single most influential trajectory on the magnitude of the indicators was early and permanent degradation of old-growth forest to secondary forest. As a result of these landscape changes, recreation and ecotourism opportunities for the entire landscape were reduced from 65,050 persons in 1976 to 25,038 persons in 1985, further declining to 22,346 and 21,608 persons in 1999 and 2007, respectively. This decrease resulted from changes in specific attributes (i.e. emblematic flora and fauna and forest structure) that were affected by forest degradation and fragmentation. These results highlight the substantial impact of LUCC on recreation opportunity decline, which mirrors biodiversity losses in the study area. 相似文献
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Ecosystem services in changing landscapes: An introduction 总被引：3，自引：3，他引：0
Louis Iverson Cristian Echeverria Laura Nahuelhual Sandra Luque 《Landscape Ecology》2014,29(2):181-186
The concept of ecosystem services from landscapes is rapidly gaining momentum as a language to communicate values and benefits to scientists and lay alike. Landscape ecology has an enormous contribution to make to this field, and one could argue, uniquely so. Tools developed or adapted for landscape ecology are being increasingly used to assist with the quantification, modelling, mapping, and valuing of ecosystem services. Several of these tools and methods encased therein are described among the eleven papers presented in this special issue, and their application has the potential to facilitate the management and promotion of services within ecosystems. Papers are associated with each of the four key categories of services that ecosystems provide to humans: supporting, provisioning, regulating, and cultural. The papers represent work conducted in eleven different countries, especially from South America. Each carries a unique approach to address a particular question pertaining to a particular set of ecosystem services. These studies are designed to inform and improve the economic, environmental and social values of the ecosystem services. This knowledge should help to develop new management alternatives for sustaining and planning ecosystems and the services they provide at different scales in space and time. We believe that these papers will create interest and inform management of some potential methods to evaluate ecosystem services at the landscape level with an integrative approach, offering new tools for management and conservation. 相似文献
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Sajad Fakhri Akram Yarmohammadi Mostafa Yarmohammadi Mohammad Hosein Farzaei Javier Echeverria 《Marine drugs》2021,19(3)
In recent decades, several neuroprotective agents have been provided in combating neuronal dysfunctions; however, no effective treatment has been found towards the complete eradication of neurodegenerative diseases. From the pathophysiological point of view, growing studies are indicating a bidirectional relationship between gut and brain termed gut-brain axis in the context of health/disease. Revealing the gut-brain axis has survived new hopes in the prevention, management, and treatment of neurodegenerative diseases. Accordingly, introducing novel alternative therapies in regulating the gut-brain axis seems to be an emerging concept to pave the road in fighting neurodegenerative diseases. Growing studies have developed marine-derived natural products as hopeful candidates in a simultaneous targeting of gut-brain dysregulated mediators towards neuroprotection. Of marine natural products, carotenoids (e.g., fucoxanthin, and astaxanthin), phytosterols (e.g., fucosterol), polysaccharides (e.g., fucoidan, chitosan, alginate, and laminarin), macrolactins (e.g., macrolactin A), diterpenes (e.g., lobocrasol, excavatolide B, and crassumol E) and sesquiterpenes (e.g., zonarol) have shown to be promising candidates in modulating gut-brain axis. The aforementioned marine natural products are potential regulators of inflammatory, apoptotic, and oxidative stress mediators towards a bidirectional regulation of the gut-brain axis. The present study aims at describing the gut-brain axis, the importance of gut microbiota in neurological diseases, as well as the modulatory role of marine natural products towards neuroprotection. 相似文献
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Maria V. Criado Irma N. Roberts Cintia G. Veliz Mariela Echeverria Flavio H. Gutierrez Boem Carla Caputo 《Archives of Agronomy and Soil Science》2018,64(4):492-504
Understanding the way in which N and P availability affects the transport of sugar and amino acids is crucial to improve grain quality and yield. Thus, in the present study, two greenhouse and field experiments were conducted with barley plants grown with different N and P availabilities to assess the dynamics of the phloem transport of assimilates in relation to the beginning of flowering and senescence. The phloem transport of assimilates decreased before the beginning of protein degradation in all treatments, but the onset of flowering and senescence varied according to the N and P availability, as evidenced by the concentrations of proteins, amino acids, and sugar and the gene expression of senescence-related proteases and all glutamine synthetase isoforms. In N-deficient plants, the phloem transport decreased before flowering, but only when P was not limiting; in N- and P-sufficient plants it decreased at flowering; and in P-deficient plants it decreased after flowering. Therefore, only N-deficient but P-sufficient plants have a post-anthesis period with high export rate of assimilates. This alteration of phenology in relation to phloem leads to important consequences in assimilate utilization, as shown by the higher yield and N content of the former compared to P-deficient plants. 相似文献