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Anthropogen verursachte Stofffrachten haben seit Beginn der Industrialisierung zur Sedimentation und Anreicherung von Schwermetallen und Schadstoffen in der weitgehend naturbelassenen Flussaue der unteren Oder geführt. Für die Grünlandnutzung in diesem Bereich des heutigen Deutsch‐Polnischen Nationalpark ergeben sich folgerichtig Einschränkungen in Form des Verbots der Milchproduktion. Boden‐, Sediment‐ und Pflanzengehalte sind seit 1990 raumbezogen analysiert worden. Hohe Gehalte im Boden haben nicht zwangsläufig hohe Pflanzengehalte bewirkt, wohl aber war sichtbar, dass die Gehalte in Senkenarealen meist höher als auf den übrigen Flächen lagen. Überhöhte Gehalte in den Pflanzen im Sinne der deutschen Futtermittelverordnung traten vor allem bei Cadmium und Mangan auf. Extensive Weidehaltung mit Mutterkühen, Mast‐ und Jungrindern ist unter Ausgrenzung von Problembereichen möglich.  相似文献   
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Routine metabolic rates of green sturgeon (Acipenser medirostris) from hatching to 31 days post hatch (dph) were determined under normoxic conditions. During the endogenous feeding stage that comprised period from hatching to 15 dph, the oxygen consumption rate (MO2, μg O2 larva−1 h−1) increased 5-fold before yolk reserves became exhausted and MO2 rates steady. The allometric relationships between MO2 and body mass had mass exponents greater than 1.0 (b=1.64±0.21) and equal to 1.0 (b=1.04±0.07) during the endogenous and exogenous feeding phases, respectively. The magnitude and changes of MO2 rates in green sturgeon larvae reflected their early ontogeny, especially during the endogenous feeding phase when the increase in metabolic rates was associated with organogenesis, acquisition of organ functions, and the conversion of yolk sac into new tissues. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
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California halibut Paralichthys californicus is an important commercial species with high aquaculture potential in Baja California Sur, México. To optimize the feeding process using live prey and/or inert diets, we evaluated alkaline proteases, pepsin, trypsin, chymotrypsin, leucine aminopeptidase, lipase, α-amylase, and acid and alkaline phosphatase activities on starved larvae and larvae fed live prey. Highest activities were observed for alkaline protease, trypsin, chymotrypsin, leucine aminopeptidase, and alkaline phosphatase in feeding larvae than starved larvae on day 4 after hatching. At day 5, a sizeable increase in all enzymatic activities was detected in feeding larvae. Alkaline protease, trypsin, chymotrypsin, and alkaline phosphatase decreases progressively from day 5 until day 18. At day 18, a slight pepsin activity was observed. This was considered an indicator of the start of digestive system maturation. We concluded that total enzymatic equipment for this species is complete between day 18 and 30 after hatching. Based on this evidence, early weaning from live prey to inert feed would be possible at this time.  相似文献   
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The osmoregulation capabilities of juvenile Siberian sturgeon exposed to three experimental osmolalities (22, 250 and 387 mOsmol kg−1) were studied over a 45-day period. Growth performance, haematological parameters, ion concentrations, gill and spiral valve Na+-K+-ATPase activities, as well as gill and spiral valve histology, were measured. At the end of the period, the plasma osmolality of fish kept in 250 and 387 mOsmol kg−1 was higher than that of fish kept in 22 mOsmol kg−1. Similar trends were observed in electrolyte concentrations. Spiral valve and gill Na+-K+-ATPase activity varied with exposure time and environmental salinity. Shortly after being transferred to hyperosmotic media, spiral valve Na+-K+-ATPase activity fell, while gill Na+-K+-ATPase activity remained constant. At the end of the experiment, gill Na+-K+-ATPase activities in fish kept in isosmotic and hyperosmotic media had increased in comparison to those of the control fish. Moreover, spiral valve Na+-K+-ATPase activities recovered and were similar to those recorded in fish kept in hyposmotic environments. Although some of the morpho-physiological mechanisms were operational in juvenile Siberian sturgeon in their adaptation to hyperosmotic media, fish cannot be considered hyperosmotic regulators as they were unable to maintain their plasma osmolality and electrolyte equilibrium in salinities higher than 250 mOsmol kg−1. This suggests that the culture of juvenile Siberian sturgeon in brackish environments is unlikely to be successful. However, our data indicate that in natural environments, juvenile Siberian sturgeon in migratory populations (Ob and Lena Rivers) would be able to migrate successfully into estuarine brackish grounds with a salinity of up to 9%. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
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Langjährige Beobachtungen der Witterungsfaktoren Temperatur und Niederschlag auf Ertrag und Pflanzenbestand von zwei Dauergrünlandstandorten verschiedener Klimagebiete wurden ausgewertet. Anlaß war das Phänomen, daß im Erzgebirge der Ertrag trotz hoher Stickstoffdungung nach dem 3. Versuchsjahr sukzessive abfiel und nach dem 12. Jahr wieder anstieg. Als Vergleich bot sich nahezu gleich bewirtschaftetes Grünland im Havelländischen Luch an.

Die Ursache fur die Ertragsdepression wurde zunächst in einer Umschichtung der Pflanzenbestände vermutet. Schließlich wurde ein Zusammenhang zwischen Witterung und Ertrag am Beispiel der Abweichungen von den Mittelwerten gefunden.  相似文献   
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ELISPOT and ELISA were standardised for pig interferon-gamma (IFN-gamma), interleukin-10 (IL-10) and interleukin-4 (IL-4) with the aim to study the evolution of the immune response in conventional pigs from birth to 6 months of age and also to compare results of both techniques. Five pigs were bled at 1, 6, 9, 12 and 22 weeks of age and peripheral blood mononuclear cells (PBMC) were stimulated with phytohemagglutinin. The frequencies of cytokine secreting cells (CSC) and the levels of secreted cytokines were compared. For IFN-gamma the mean of CSC increased with age (p<0.05) from an average of 486/10(6) PBMC at first week of age to 1256/10(6) PBMC at 22 weeks of age. No correlation was found between the number of IFN-gamma CSC and the cytokine levels obtained by ELISA. For IL-10, frequencies of CSC did not increase with age of pigs, having a low of 315/10(6) PBMC at first week of age and a high of 1485/10(6) PBMC at six weeks. Comparison of ELISA and ELISPOT results for IL-10 showed a certain degree of correlation (r=0.74; p<0.05). Spontaneous secretion was observed in unstimulated cultures. For IL-4, frequencies of CSC were low (50-70/10(6) PBMC). In this case, comparison of ELISA and ELISPOT could not be done because cytokine levels in culture supernatants were often below the detection limit of the IL-4 ELISA. All these values can serve as a reference for future studies and also, our observations suggest that ELISPOT and ELISA should be carefully interpreted and do not necessarily correlate.  相似文献   
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