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排序方式: 共有877条查询结果,搜索用时 31 毫秒
51.
Sandrelli F Tauber E Pegoraro M Mazzotta G Cisotto P Landskron J Stanewsky R Piccin A Rosato E Zordan M Costa R Kyriacou CP 《Science (New York, N.Y.)》2007,316(5833):1898-1900
Diapause is a protective response to unfavorable environments that results in a suspension of insect development and is most often associated with the onset of winter. The ls-tim mutation in the Drosophila melanogaster clock gene timeless has spread in Europe over the past 10,000 years, possibly because it enhances diapause. We show that the mutant allele attenuates the photosensitivity of the circadian clock and causes decreased dimerization of the mutant TIMELESS protein isoform to CRYPTOCHROME, the circadian photoreceptor. This interaction results in a more stable TIMELESS product. These findings reveal a molecular link between diapause and circadian photoreception. 相似文献
52.
Two types of consolidated memory have been described in Drosophila, anesthesia-resistant memory (ARM), a shorter-lived form, and stabilized long-term memory (LTM). Until now, it has been thought that ARM and LTM coexist. On the contrary, we show that LTM formation leads to the extinction of ARM. Flies devoid of mushroom body vertical lobes cannot form LTM, but spaced conditioning can still erase their ARM, resulting in a remarkable situation: The more these flies are trained, the less they remember. We propose that ARM acts as a gating mechanism that ensures that LTM is formed only after repetitive and spaced training. 相似文献
53.
Pimenta BV Haddad CF Nascimento LB Cruz CA Pombal JP 《Science (New York, N.Y.)》2005,309(5743):1999; author reply 1999
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Observations of internal wave velocity fluctuations show that enhanced turbulent mixing over rough topography in the Southern Ocean is remarkably intense and widespread. Mixing rates exceeding background values by a factor of 10 to 1000 are common above complex bathymetry over a distance of 2000 to 3000 kilometers at depths greater than 500 to 1000 meters. This suggests that turbulent mixing in the Southern Ocean may contribute crucially to driving the upward transport of water closing the ocean's meridional overturning circulation, and thus needs to be represented in numerical simulations of the global ocean circulation and the spreading of biogeochemical tracers. 相似文献
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Hurtado-Fernández E Carrasco-Pancorbo A Fernández-Gutiérrez A 《Journal of agricultural and food chemistry》2011,59(6):2255-2267
A powerful HPLC-DAD-ESI-TOF MS method was established for the efficient identification of the chemical constituents in the methanolic extracts of avocado (Persea americana). Separation and detection conditions were optimized by using a standard mix containing 39 compounds belonging to phenolic acids and different categories of flavonoids, analytes that could be potentially present in the avocado extracts. Optimum LC separation was achieved on a Zorbax Eclipse Plus C18 analytical column (4.6×150 mm, 1.8 μm particle size) by gradient elution with water+acetic acid (0.5%) and acetonitrile as mobile phases, at a flow rate of 1.6 mL/min. The detection was carried out by ultraviolet-visible absorption and ESI-TOF MS. The developed method was applied to the study of 3 different varieties of avocado, and 17 compounds were unequivocally identified with standards. Moreover, around 25 analytes were tentatively identified by taking into account the accuracy and isotopic information provided by TOF MS. 相似文献
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Verardo V Arraez-Roman D Segura-Carretero A Marconi E Fernandez-Gutierrez A Caboni MF 《Journal of agricultural and food chemistry》2011,59(14):7700-7707
Nowadays there is considerable interest in the consumption of alternative crops as potential recipes for gluten-free products production. Therefore, the use of buckwheat for the production of gluten-free pasta has been investigated in the present study. RP-HPLC-ESI-TOF-MS has been applied for the separation and characterization of free and bound phenolic compounds in buckwheat flour and buckwheat spaghetti. Thus, 32 free and 24 bound phenolic compounds in buckwheat flour and spaghetti have been characterized and quantified. To the authors' knowledge, protochatechuic-4-O-glucoside acid and procyanidin A have been detected in buckwheat for the first time. The results have demonstrated a decrease of total free phenolic compounds from farm to fork (from flour to cooked spaghetti) of about 74.5%, with a range between 55.3 and 100%, for individual compounds. The decrease in bound phenols was 80.9%, with a range between 46.2 and 100%. The spaghetti-making process and the cooking caused losses of 46.1 and 49.4% of total phenolic compounds, respectively. Of the total phenolic compounds present in dried spaghetti, 11.6% were dissolved in water after cooking. 相似文献
60.
Colomer I Aguado P Medina P Heredia RM Fereres A Belda JE Viñuela E 《Pest management science》2011,67(10):1237-1244
BACKGROUND: Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) and Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) are among the most serious pests of sweet peppers in greenhouses. Chemical control is difficult because of their high reproductive rates and insecticide resistance, and seasonal inoculative releases of Orius laevigatus (Fieber) and Amblyseius swirskii (Athias‐Henriot) are commonly used to reduce their populations. As chemical treatments are often needed in the crop against other pests, the side effects of methoxyfenozide (an insect growth regulator against lepidopteran pests) and flonicamid (a selective feeding inhibitor against sucking insects) were studied in both beneficial organisms in a commercial greenhouse. RESULTS: Orius laevigatus and A. swirskii were released at commercial rates (4–5 and 100 m?2), and a strong establishment and a very homogeneous distribution were reached. One pesticide treatment with the maximum field recommended concentration of methoxyfenozide and flonicamid (96 and 100 mg AI L?1) was done when they were well established, and their population levels were not affected either immediately or up to 30 days after treatment. CONCLUSION: The results are indicative of no impact of methoxyfenozide and flonicamid on the two natural enemies in the field, and both can be considered as potential alternatives to be included in IPM programmes in sweet pepper. Copyright © 2011 Society of Chemical Industry 相似文献