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The concern of this paper is to study local approximation properties of the Bernstein-Durrmeyer operators Mn. We derive the complete asymptotic expansion of the operators Mn and their derivatives as n tends to infinity. It turns out that the appropriate representation is a series of reciprocal factorials. All coefficients are calculated explicitly in a very concise form. Our main theorem contains several earlier partial results as special cases. Finally, we obtain a Voronovskaja-type formula for simultaneous approximation by linear combinations of Mn,

关键词： oscillatory integral operator multiplier singularity

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Na^+-k^+-ATPase activity of hepatocyte plasma membranes,reversible and irreversible alterations due to bile acids

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Chinese Medical Journal 1998年第1期111卷 93-93页

作者： T. You, S. Guldutuna, S. Bhatti and U. leuschner Gastroenterology Center of Internal Medical University Hospital D-60590 Frankfurt-Main Germany

Background Chenodeoxycholic acid (CDC) is an apolar bile salt and damages hepatocytes, whereas ursodeoxycholic acid (UDC) is a more polar bile salt and protects liver cell against toxic bile salts. We therefore investigated the activity of membrane associated Na + k + ATPase, a coenzyme of the sodium dependent bile salt carrier. Methods Liver plasma membranes (LPM) were isolated from rat livers according to the method of Song et al (J Cell Biol 1969; 41:124). The LPM were incubated with bile salts (TUDC, UDC, TCDC, CDC) in concentrations of 0.1 2 mmol/L for 0 30 minutes at room temperature. To study reversibility of the effect of CDC, LPM were diluted with buffer 50 times of volume after incubation. The activity of membrane associated Na + k+ ATPase was determined enzymatically at 37℃ and the phospholipid (PL) release into the supernatant was measured. Results CDC and TCDC both showed a dose dependent inhibition of the enzyme activity (Pkfurt Main, Germany (You T, Guldutuna S, Bhatti S and leuschner U)Initially TCDC induced an increase in enzyme activity at concentrations of 0.1 1 mmol/L, however, after 3 minutes activity repidly decreased to less than 30% of controls. Up to a concentration of 1 mmol/L CDC the inhibition of enzyme activity could be reversed by diluting the bile salt in the incubation medium. At a concentration of 2 mmol/L CDC activity was only partially restored and at this concentration a marked PL release into the supernatant was observed, indicating solubilization of the membranes. UDC did not decrease the enzyme activity at concentrations of 0.1 2 mmol/L. At a concentration of 2 mmol/L TUDC inhibited the Na + k + ATPase by about 20%. Solubilization of membrane PL was not observed. Conclusion CDC and TCDC inhibited Na + k + ATPase. Dilution of the bile salt with buffer reversed the inhibitory effect up to conc

关键词： ATPase activity of hepatocyte plasma membranes,reversible and irreversible alterations due to bile acids Na

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Regeneration of Nothofagus dombeyi(Mirb.)Ø*** little to moderately disturbed southern beech forests in the Andes of Patagonia(Argentina)

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森林生态系统:英文版 2023年第4期10卷 472-482页

作者： Stefan Zerbe Stefanie T.Storz Georg Leitinger Natalia Zoe Joelson JoséBava Steffi Heinrichs Christoph leuschner Gabriel Loguercio Alois Simon María F.Urretavizcaya Helge Walentowski Faculty of Agricultural Environmental and Food SciencesFree University of Bozen-BolzanoBolzanoItaly Department of Ecology University of InnsbruckInnsbruckAustria Faculty of Resource Management HAWK University of Applied Sciences and ArtsGöttingenGermany Department of Plant Ecology and Ecosystem Research Albrecht-von-Haller-Institute for Plant SciencesUniversity of GöttingenGöttingenGermany Centro de Investigación y Extensión Forestal Andino Patagónico(CIEFAP) EsquelArgentina Department of Forest Planning Tyrol Forest AdministrationOffice of the Tyrolean GovernmentInnsbruckAustria

Natural forests and stands subjected to little to moderate human impact are continuously declining worldwide and with these,their biodiversity and ecosystem *** Nothofagus forests in the south of the South American continent are in a pristine state or only moderately impacted by *** grazing by livestock,in the past and still today often practiced in a non-sustainable way is,however,increasingly under discussion to meet current environmental and socio-economic ***,we investigate the regeneration of Nothofagus dombeyi,a keystone species of the Patagonian Andes,in secondary forests in Argentinian northern Patagonia,particularly addressing the role of disturbance through grazing by livestock at various *** test the hypothesis that the regeneration of this tree species is favored by grazing impact and,thus,disturbance of the herb layer and soil *** support of our hypothesis,Nothofagus dombeyi regeneration was significantly higher in terms of individuals and height classes in moderately grazed *** analysis shows significant positive effects of moderate grazing pressure,herb layer cover,and the occurrence of bare soil on the regeneration of Nothofagus *** results show that an integration of livestock grazing and forest regeneration is possible and that agroforestry systems can be an adequate management option for stakeholders in the region.A grazing management can also be part of a forest fire prevention ***,the regeneration success and grazing pressure should be continuously monitored.

关键词： Agroforestry Disturbance Fire management Forest grazing Forest management Plant traits

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熊脱氧胆酸(UDCA)治疗慢性胆汁郁积性肝病

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德国医学 1996年第3期13卷 167-167页

作者： U.leuschner 彭慧 Johann Wolfgang Goethe-Universitt Frankfurt am MainGermany 同济医科大学附属同济医院

在肝脏疾病中,熊脱氧胆酸(ursodeoxycholicacid,UDCA)是1985年开始首次运用于治疗慢性活动性肝炎,经治疗后碱性磷酸酶,γ-谷氨酰胺转肽酶及转氨酶类这些指标发生明显改善,肝脏组织学也未见恶化。几组无对照的研究显示 UDCA

关键词：肝疾病胆汁郁积性药物疗法熊脱氧胆酸

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