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排序方式: 共有482条查询结果,搜索用时 15 毫秒
461.
Fernando Ayllon Jose L. Martinez Patrick Davaine Edward Beall Eva Garcia-Vazquez 《Aquaculture (Amsterdam, Netherlands)》2004,230(1-4):81-88
In the subantarctic French territory of the Kerguelen Islands, Atlantic salmon Salmo salar was stocked to create a new population in the Korrigans drainage system. The analysis of historical scale collections showed that hybrids were inadvertently introduced with the original Atlantic salmon stocks. Later colonization of the Korrigans system by brown trout Salmo trutta was followed by interspecific hybridization between the two species. Our results highlight the importance of both routine genetic monitoring of hatchery stocks and considering the possible influence of other species when stocking is envisaged. 相似文献
462.
463.
E E Martinez W Shimoda 《Journal of the Association of Official Analytical Chemists》1988,71(3):477-480
A liquid chromatographic method for the multiresidue determination of tetracyclines (TCs) in feeds is described. The levels of quantitation were 10 ppm each for tetracycline-HCl (TC), oxytetracycline (OTC), and chlortetracycline-HCl (CTC); the detection limit was 40 ppb for each. The calibration curves were linear between 2.5 and 100 ppm. The procedure involved double extraction with pH 2.0 and pH 4.5 McIlvain buffers, cleanup on a Sephadex LH-20 column, separation on a Nova-Pak C18 column, and detection at 370 nm. Recoveries of 10 micrograms/g of each TC in multiresidue feed samples ranged from 55.8 to 75.5% for OTC, 71.6 to 100% for TC, and 22.4 to 60.6% for CTC. The identities of the TCs were confirmed by thin layer chromatography. 相似文献
464.
Miranda-Rottmann S Aspillaga AA Pérez DD Vasquez L Martinez AL Leighton F 《Journal of agricultural and food chemistry》2002,50(26):7542-7547
Oxidative modification of low-density lipoprotein (LDL) particles is a key event in the development of atherosclerosis. Oxidized LDL induces oxidative stress and modifies gene expression in endothelial cells. Berries constitute a rich dietary source of phenolic antioxidants. We found that the endemic Chilean berry Aristotelia chilensis (ach) has higher phenol content and scores better for total radical-trapping potential and total antioxidant reactivity in in vitro antioxidant capacity tests, when compared to different commercial berries. The juice of ach is also effective in inhibiting copper-induced LDL oxidation. In human endothelial cell cultures, the addition of ach juice significantly protects from hydrogen peroxide-induced intracellular oxidative stress and is dose-dependent. The aqueous, anthocyanin-rich fraction of ach juice accounts for most of ach's antioxidant properties. These results show that ach is a rich source of phenolics with high antioxidant capacity and suggest that it may have antiatherogenic properties. 相似文献
465.
Martinez I Bathen T Standal IB Halvorsen J Aursand M Gribbestad IS Axelson DE 《Journal of agricultural and food chemistry》2005,53(17):6889-6895
This work investigates the suitability of (1)H NMR spectroscopy to identify the fate of some bioactive compounds in seafood submitted to several processing conditions and examines the possibility of using (1)H NMR spectroscopy profiling to classify such products. Perchloric acid extracts of cod white muscle from newly killed and (i) unprocessed, (ii) boiled, and (iii) fried fillets and from (iv) frozen fillets, (v) the frozen fillets after thawing, and (vi) their drip loss and from (vii) rehydrated cod klippfish (n = 5) were analyzed by 500 MHz (1)H NMR spectroscopy. It was possible to identify taurine, betaine, anserine, creatine, and trimethylamine oxide (TMAO) in all extracts examined, and frozen fish was recognizable by the presence of dimethylamine (DMA). None of the heating procedures seemed to induce the loss of bioactive compounds from the fillet, but freezing and thawing did: the compounds were lost in what is known as drip loss. About 80% of the samples were correctly classified using a probabilistic neural network procedure having as inputs the scores of the first 20 principal components of the principal component analysis of a selected region of the NMR spectra. 相似文献
466.
The microfungal community of an andosol, under an acid beech forest located in a zone of the Province of Navarra (Spain) characterized by a temperate climate and high rainfall was studied. Mycelial length, number of spores and fungal biomass were eslimated by the agar-film technique. The number of fungal propagules were estimated by plate counting. There was a pronounced decrease of fungal propagules and mycelial biomass with soil depth; the highest values were obtained in the spring and the autumn. Seasonal variations were attenuated with increasing depth. In autumn the leaves of the A00 horizon contained a great number of fungal spores but there was little mycelial growth. 相似文献
467.
Matteo Garbarino Emanuele Lingua Marta Martinez Subirà Renzo Motta 《European Journal of Forest Research》2011,130(4):491-502
As a consequence of land abandonment and marginalization, open areas and traditionally managed wood pastures are disappearing
from many alpine valleys. Landscape and stand scale dynamics were analyzed in two neighboring inner valleys of central Italian
Alps (Valmalenco, SO) dominated by larch (Larix decidua Mill.) forests and experiencing different historical land use intensities. Land cover mapping obtained from object-oriented
analysis of aerial photographs was used to quantify land cover changes between 1961 and 2003. Spatial statistics were used
to quantify landscape patterns, and intensive sampling in permanent plots was employed to perform point pattern analysis at
the stand scale. Expansion of forested area at the expense of wood pastures was the main land cover transition observed. Differences
in land use intensities were responsible for different patterns at the landscape scale: (1) heavier grazing and human pressure
created a more diverse and fragmented mosaic of meadows, open woodlands, forests and wood pastures, (2) lower human impact
favored a more homogeneous and stable system. A decline in grazing pressure in the late 1970s favored the establishment of
larch and spruce in a clustered pattern, typical of the subalpine belt. Subalpine wood pastures, likewise many other semi-natural
environments, are in danger of disappearing and lose their productive and cultural characteristics, because they are developing
into more closed and dense stands. 相似文献
468.
469.
Martinez RN Sereno PC Alcober OA Colombi CE Renne PR Montañez IP Currie BS 《Science (New York, N.Y.)》2011,331(6014):206-210
Upper Triassic rocks in northwestern Argentina preserve the most complete record of dinosaurs before their rise to dominance in the Early Jurassic. Here, we describe a previously unidentified basal theropod, reassess its contemporary Eoraptor as a basal sauropodomorph, divide the faunal record of the Ischigualasto Formation with biozones, and bracket the formation with (40)Ar/(39)Ar ages. Some 230 million years ago in the Late Triassic (mid Carnian), the earliest dinosaurs were the dominant terrestrial carnivores and small herbivores in southwestern Pangaea. The extinction of nondinosaurian herbivores is sequential and is not linked to an increase in dinosaurian diversity, which weakens the predominant scenario for dinosaurian ascendancy as opportunistic replacement. 相似文献
470.