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The molecular profile of 30 Moraxella bovis strains, recovered from outbreaks of infectious bovine keratoconjunctivitis in Argentina, Brazil and Uruguay between 1974 and 2001, was determined through randomly applied polymorphic DNA (RAPD) analysis. Molecular profiles of nine strains recovered after 1990 varied from those recovered before 1990. The profiles of 13 strains (48%) differed from those of three vaccinal strains extensively used since 1984 in Argentina and Uruguay. Eight Argentinean strains, one from Brazil and two from Uruguay had identical RAPD profiles. Strains belonging to different serogroups had identical RAPD profiles, demonstrating that this technique was not able to discriminate among strains with low cross-reactivity indices. RAPD may be helpful in the primary characterization of M. bovis strains, but it does not replace serological characterization.  相似文献   
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Global mineralogical mapping of Mars by the Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activité (OMEGA) instrument on the European Space Agency's Mars Express spacecraft provides new information on Mars' geological and climatic history. Phyllosilicates formed by aqueous alteration very early in the planet's history (the "phyllocian" era) are found in the oldest terrains; sulfates were formed in a second era (the "theiikian" era) in an acidic environment. Beginning about 3.5 billion years ago, the last era (the "siderikian") is dominated by the formation of anhydrous ferric oxides in a slow superficial weathering, without liquid water playing a major role across the planet.  相似文献   
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We evaluated the water characteristics and particle sedimentation in Macrobrachium amazonicum (Heller 1862) grow‐out ponds supplied with a high inflow of nutrient‐rich water. Prawns were subject to different stocking and harvesting strategies: upper‐graded juveniles, lower‐graded juveniles, non‐graded juveniles+selective harvesting and traditional farming (non‐grading juveniles and total harvest only). Dissolved oxygen, afternoon N‐ammonia and N‐nitrate and soluble orthophosphate were lower in the ponds in comparison with inflow water through the rearing cycle. Ponds stocked with the upper population fraction of graded prawns showed higher turbidity, total suspended solids and total Kjeldahl nitrogen than the remaining treatments. An increase in the chemical oxygen demand:biochemical oxygen demand ratio from inlet (4.9) to pond (7.1–8.0) waters indicated a non‐readily biodegradable fraction enhancement in ponds. The sedimentation mean rate ranged from 0.08 to 0.16 mm day?1 and sediment contained >80% of organic matter. The major factors affecting pond ecosystem dynamic were the organic load (due to primary production and feed addition) and bioturbation caused by stocking larger animals. Data suggest that M. amazonicum grow‐out in ponds subjected to a high inflow of nutrient‐rich water produce changes in the water properties, huge accumulation of organic sediment at the pond bottom and non‐readily biodegradable material in the water column. However, the water quality remains suitable for aquaculture purposes. Therefore, nutrient‐rich waters, when available, may represent a source of unpaid nutrients, which may be incorporated into economically valued biomass if managed properly.  相似文献   
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Growth hormone (GH) can be orally administrated to fish in order to increase growth rates. Fish growth is characterized by the hyperplasia and hypertrophy of muscle fibre throughout adult life. In this respect, GH could affect directly and indirectly (by growth and metabolic factors) the development and growth of muscle fibres. Recombinant pejerrey GH (r‐pjGH) was expressed in Escherichia coli and refolded in a highly efficient batch dilution system, obtaining 0.1 g L?1 of hormone without protein precipitation during the refolding procedure. Orally administered hormone to pejerrey produced a 30% increase in mean weight and stimulated liver insulin‐like growth factor type I (IGF‐I) mRNA expression after 1 month of treatment. Histological analyses showed that muscle growth was generated mainly by hypertrophy of the fibres. A higher r‐pjGH dose increased muscle fibre hypertrophy but somatic growth was negatively affected probably due to a reduced capacity of generating new fibres.  相似文献   
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Tropical arthropod surveys generally use a combination of complementary sampling methods to increase the detection of species and individuals, and to decrease the number of singletons. However, given the high arthropod abundance and the taxonomic challenges of arthropod surveys, the combination of different sampling methods may be inefficient and may increase survey costs. Harvestmen were sampled using beating tray, nocturnal search, leaf-litter manual sorting and Winkler apparatus in 70 plots distributed in two areas in Central Amazonia. Every sampled method documented different assemblages, and only the nocturnal search method proved to be efficient in representing both harvestmen richness and composition. Given the data collected from leaf-litter manual sorting, Winkler apparatus and beating tray can be used in inventories to increase the number of species collected, but may be less useful for applied or monitoring studies. Although pooling data from three methods was effective to obtain an overview of species richness, it may not be the more efficient strategy for studies of assemblage associations with environmental variables. As each method may sample distinct assemblages that have different responses to the surrounding environment, pooling data from these different methods may obfuscate patterns of assemblage composition related to environmental factors instead of clarifying them.  相似文献   
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Araucaria forest, named due to the high abundance of Araucaria angustifolia, occurs mainly in the southern Brazilian highlands, and the abundance of A. angustifolia in the forest is a current forest issue. The present study aimed at evaluating a potential allelopathic effect of A. angustifolia needle extracts that could mediate plant successional dynamics in the Araucaria forests. Senescent araucaria needles from A. angustifolia were evaluated for their allelopathic potential on Lactuca sativa through an in vitro study. The effect was evaluated by determining the germination of seeds, length of seedling and germination rate. The allelopathic potential of the A. angustifolia was confirmed for the highest doses tested (187.5 and 250?mg of the extracts). The potential allelochemical compounds identified were ent-kaurene and phyllocladene. In conclusion, A. angustifolia showed a potential allelophatic effect that may play an important role in successional dynamics of Araucaria forests.  相似文献   
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Several studies have shown the benefit of the use of probiotics in the prevention and treatment of diseases; however, few of them have investigated the effect of probiotics on parasitosis. In this study, the effect of Saccharomyces boulardii on the intensity of infection of mice with toxocariasis was evaluated. The animals were fed with a diet supplemented with S. boulardii for 15 days before inoculation with Toxocara canis eggs and for 2 or 60 days post-inoculation. S. boulardii promoted a reduction of approximately 36% in the average number of recovered T. canis larvae, suggesting that it can be used as an alternative to help control toxocariasis.  相似文献   
10.
Abstract. This study reports the detection of antibodies against Brucella abortus and B. canis in wild neotropical carnivores kept in captivity in three zoos in northeastern Brazil. A total of 42 serum samples were examined, 17 from coatis (Nasua nasua), eight from crab-eating raccoons (Procyon cancrivorus), three from crab-eating foxes (Cerdocyon thous), three from hoary foxes (Lycalopex vetulus), two from little spotted cats (Leopardus tigrinus), five from tayras (Eira barbara), two from greater grisons (Galictis vittata), and two from neotropical river otters (Lontra longicaudis). The Rose-Bengal test and complement fixation test (CFT) were performed to detect anti-Brucella spp. antibodies, whereas the agar gel immunodiffusion test (AGID) was employed to detect anti-B. canis antibodies. The overall seroprevalence varied by species and by test; in addition, CFT and AGID seemed better able to detect antibodies against B. abortus and B. canis, respectively. This is the first study on the presence of anti-Brucella spp. antibodies in captive carnivores from Brazil, as well as the first report of antibodies to Brucella spp. in coatis, crab-eating raccoons, hoary foxes, little spotted cats, tayras, and greater grisons.  相似文献   
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