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排序方式: 共有256条查询结果,搜索用时 15 毫秒
251.
Bibring JP Langevin Y Gendrin A Gondet B Poulet F Berthé M Soufflot A Arvidson R Mangold N Mustard J Drossart P;OMEGA team 《Science (New York, N.Y.)》2005,307(5715):1576-1581
The Observatoire pour la Minéralogie, l'Eau, les Glaces, et l'Activité (OMEGA) investigation, on board the European Space Agency Mars Express mission, is mapping the surface composition of Mars at a 0.3- to 5-kilometer resolution by means of visible-near-infrared hyperspectral reflectance imagery. The data acquired during the first 9 months of the mission already reveal a diverse and complex surface mineralogy, offering key insights into the evolution of Mars. OMEGA has identified and mapped mafic iron-bearing silicates of both the northern and southern crust, localized concentrations of hydrated phyllosilicates and sulfates but no carbonates, and ices and frosts with a water-ice composition of the north polar perennial cap, as for the south cap, covered by a thin carbon dioxide-ice veneer. 相似文献
252.
Bursztyka J Debrauwer L Perdu E Jouanin I Jaeg JP Cravedi JP 《Journal of agricultural and food chemistry》2008,56(12):4832-4839
Vinclozolin is a dicarboxymide fungicide that presents antiandrogenic properties through its two hydrolysis products M1 and M2, which bind to the androgen receptor. Because of the lack of data on the biotransformation of vinclozolin, its metabolism was investigated in vitro in precision-cut rat liver slices and in vivo in male rat using [ (14)C]-vinclozolin. Incubations were performed using different concentrations of substrate, and the kinetics of formation of the major metabolites were studied. Three male Wistar rats were fed by gavage with [ (14)C]-VZ. Urine was collected for 24 h and analyzed by radio-HPLC for metabolic profiling. Metabolite identification was carried out on a LCQ ion trap mass spectrometer. In rat liver slices and in vivo, the major primary metabolite has been identified as 3',5'-dichloro-2,3,4-trihydroxy-2-methylbutyranilide (M5) and was mainly present as glucuronoconjugates. M5 is produced by dihydroxylation of the vinyl group of M2. Other metabolites have been identified as 3-(3,5-dichlorophenyl)-5-methyl-5-(1,2-dihydroxyethyl)-1,3-oxazolidine-2,4-dione (M4), a dihydroxylated metabolite of vinclozolin, which undergoes further conjugation to glucuronic acid, and 2-[[(3,5-dichlorophenyl)-carbamoyl]oxy]-2-methyl-3,4-dihydroxy-butanoic acid (M6), a dihydroxylated metabolite of M1. 相似文献
253.
254.
OBJECTIVE: To evaluate whether bronchoalveolar lavage (BAL) alters respiratory mechanics of horses with recurrent airway obstruction (ie, heaves) over a 48-hour period. ANIMALS: 6 horses affected with heaves. PROCEDURES: Horses were subjected to a complete BAL procedure, which included sedation with xylazine and butorphanol, intratracheal administration of lidocaine, and instillation and aspiration of two 250-mL boluses of saline (0.9% NaCl) solution through an endoscope (study 1). To evaluate the effects of saline solution, horses were subjected to the same procedure without saline solution instillation and aspiration (study 2). Lastly, the endoscope was similarly introduced into the lower airways, without sedation or saline instillation and aspiration (study 3). Respiratory mechanics were performed at baseline (time 0) and at 3, 6, 12, 24, and 48 hours after each procedure. RESULTS: In study 1, BAL induced a significant decrease in pulmonary resistance lasting up to 6 hours. This may have resulted from clearance of mucus in large airways. We also observed a significant increase in lung elastance and transpulmonary pressure at 12 hours after BAL in all 3 studies, which may be attributed to a circadian effect. CONCLUSIONS AND CLINICAL RELEVANCE: Our results indicate that the temporal effects of BAL procedures on lung mechanics should be taken into account when designing research protocols involving horses with heaves. Future studies should address the immediate effects of BAL on lung function. 相似文献
255.
Weisstaub NV Zhou M Lira A Lambe E González-Maeso J Hornung JP Sibille E Underwood M Itohara S Dauer WT Ansorge MS Morelli E Mann JJ Toth M Aghajanian G Sealfon SC Hen R Gingrich JA 《Science (New York, N.Y.)》2006,313(5786):536-540
Serotonin [5-hydroxytryptamine (5-HT)] neurotransmission in the central nervous system modulates depression and anxiety-related behaviors in humans and rodents, but the responsible downstream receptors remain poorly understood. We demonstrate that global disruption of 5-HT2A receptor (5HT2AR) signaling in mice reduces inhibition in conflict anxiety paradigms without affecting fear-conditioned and depression-related behaviors. Selective restoration of 5HT2AR signaling to the cortex normalized conflict anxiety behaviors. These findings indicate a specific role for cortical 5HT2AR function in the modulation of conflict anxiety, consistent with models of cortical, "top-down" influences on risk assessment. 相似文献
256.
Astère Bararyenya Pierre-Claver Nahayo Anicet Nduwimana Pierre Niyonzima Déo Nyawakira Jean-Pierre Sindihebura Ernest Vyizigiro Vital Ndayishimiye Anton J. Haverkort 《Potato Research》2018,61(1):73-88
From 2014 through 2016, on-farm experiments were carried out in three provinces surrounding Bujumbura town in Burundi to improve the low potato (Solanum tuberosum) yields, which currently stand at about 6 t ha?1. It was hypothesised that in rain-fed conditions, improved varieties, healthier seed tubers, pre-sprouting in light, proper fertilisation and protection from late blight attack would improve yield and quality, such as tuber weight, tuber size and lower brown rot incidence. The treatments in the on-farm trials at five farms in each of three sites (15 replicates) were applied in two seasons, giving 30 replicates in 580 plots. The following treatments were compared with growers’ current practices: introduction of two new varieties, use of early generation seed from a rapid multiplication scheme, earlier harvesting of a seed crop, seed storage in a diffused light store, and research-based timing and dose rate of fertilisers and fungicides. Marginal rates of return on investments were calculated at farm level and current and tested alternative technologies were compared. Costs and benefits of applying such techniques were calculated. An improved variety contributed up to 20% yield increase and healthier seed 80%. Early harvesting reduced yield by 30% and reduced incidence of brown rot in the current season, but increased it (from 21 to 39%) in the following season when tubers were replanted. Diffused light storage, alternating contact and systemic fungicide application, and application of chemical fertilisers resulted in 30, 50 and 60% yield increases, respectively. It was shown that it is possible to double yields and economic returns (marginal rates of return) under the growing conditions in Burundi when growers plant healthy pre-sprouted seed of a new variety and apply chemical fertilisers and fungicides. 相似文献