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排序方式: 共有116条查询结果,搜索用时 15 毫秒
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DN Basov SI Woods AS Katz EJ Singley RC Dynes M Xu DG Hinks CC Homes M Strongin 《Science (New York, N.Y.)》1999,283(5398):49-52
Analysis of the interlayer infrared conductivity of cuprate high-transition temperature superconductors reveals an anomalously large energy scale extending up to midinfrared frequencies that can be attributed to formation of the superconducting condensate. This unusual effect is observed in a va- riety of materials, including Tl2Ba2CuO6+x, La2-xSrxCuO4, and YBa2Cu3O6.6, which show an incoherent interlayer response in the normal state. Midinfrared range condensation was examined in the context of sum rules that can be formulated for the complex conductivity. One possible interpretation of these experiments is in terms of a kinetic energy change associated with the superconducting transition. 相似文献
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PO Wennberg TF Hanisco L Jaegle DJ Jacob EJ Hintsa EJ Lanzendorf JG Anderson R Gao ER Keim SG Donnelly LAD Negro DW Fahey SA McKeen RJ Salawitch CR Webster RD May RL Herman MH Proffitt JJ Margitan EL Atlas SM Schauffler F Flocke CT McElroy TP Bui 《Science (New York, N.Y.)》1998,279(5347):49-53
The concentrations of the hydrogen radicals OH and HO2 in the middle and upper troposphere were measured simultaneously with those of NO, O3, CO, H2O, CH4, non-methane hydrocarbons, and with the ultraviolet and visible radiation field. The data allow a direct examination of the processes that produce O3 in this region of the atmosphere. Comparison of the measured concentrations of OH and HO2 with calculations based on their production from water vapor, ozone, and methane demonstrate that these sources are insufficient to explain the observed radical concentrations in the upper troposphere. The photolysis of carbonyl and peroxide compounds transported to this region from the lower troposphere may provide the source of HOx required to sustain the measured abundances of these radical species. The mechanism by which NO affects the production of O3 is also illustrated by the measurements. In the upper tropospheric air masses sampled, the production rate for ozone (determined from the measured concentrations of HO2 and NO) is calculated to be about 1 part per billion by volume each day. This production rate is faster than previously thought and implies that anthropogenic activities that add NO to the upper troposphere, such as biomass burning and aviation, will lead to production of more O3 than expected. 相似文献
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M. A. Smith D. G. Levine L. M. Getman E. J. Parente J. B. Engiles 《Equine Veterinary Education》2009,21(1):11-16
This report describes the diagnosis and treatment of vulvar papillomatosis with carcinoma in situ in a 25‐year‐old mare. Papillomavirus was demonstrated via immunohistochemical staining of biopsies of the lesion. The papillomas were removed via laser excision and the surrounding vulvar tissue injected with 5‐fluorouracil. Additional more extensive laser excisions were required due to recurrence. 相似文献
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Zotta T Piraino P Ricciardi A McSweeney PL Parente E 《Journal of agricultural and food chemistry》2006,54(7):2567-2574
Model wheat doughs started with six different lactic acid bacteria (LAB), with or without a commercial baker's yeast culture, were used to study proteolysis in sourdough fermentations. Cell counts, pH, and free amino acid concentration were measured. Sequential extraction of dough samples was performed to separate wheat proteins. The salt-soluble protein fraction (albumins and globulins) was analyzed by RP-HPLC and SDS-PAGE, whereas propanol-soluble (gliadins) and insoluble (glutenins) protein fractions were analyzed by SDS-PAGE only. Multivariate statistical methods were used for the analysis of results. The presence of yeasts and LAB affected RP-HPLC and SDS-PAGE patterns of the salt-soluble fraction in a complex way. The only changes in the gluten proteins that could be related to the presence of LAB were the appearance of new protein fragments (20 and 27 kDa) from gliadins and the degradation of high molecular weight glutenin subunits. 相似文献
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A 23-year-old, male short-beaked echidna ( Tachyglossus aculeatus ) housed at a North American zoo was successfully treated for flea-associated anaemia, but subsequently died. Cause of death was presumptive septicaemia secondary to splenic lymphoma. This is only the fifth case of neoplasia reported in this monotreme species, and the first from outside of Australia. 相似文献
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Two polysaccharides with mean M(r)s of 2.0 x 10(6) and 3.75 x 10(5), were isolated from powdered seeds of Centrosema pubescens by fractionation on Sephacryl S-300 HR. Chemical and spectroscopic studies indicated that they have a backbone chain composed of beta-(1-->4)-linked D-galactopyranose residues having branches composed of alpha-(1-->5)-linked L-arabinofuranose residues at position 6 of D-galactose of the backbone chain. The polysaccharides showed reticuloendothelial system-potentiating activity in a carbon clearance test. 相似文献
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