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I Frías MT Caldeira JR Pérez-Casti?eira JP Navarro-Avi?ó FA Culia?ez-Maciá O Kuppinger H Stransky M Pagés A Hager R Serrano 《Canadian Metallurgical Quarterly》1996,8(9):1533-1544
The plasma membrane (PM) H(+)-ATPase has been proposed to play important transport and regulatory roles in plant physiology, including its participation in auxin-induced acidification in coleoptile segments. This enzyme is encoded by a family of genes differing in tissue distribution, regulation, and expression level. A major expressed isoform of the maize PM H(+)-ATPase (MHA2) has been characterized. RNA gel blot analysis indicated that MHA2 is expressed in all maize organs, with highest levels being in the roots. In situ hybridization of sections from maize seedlings indicated enriched expression of MHA2 in stomatal guard cells, phloem cells, and root epidermal cells. MHA2 mRNA was induced threefold when nonvascular parts of the coleoptile segments were treated with auxin. This induction correlates with auxin-triggered proton extrusion by the same part of the segments. The PM H(+)-ATPase in the vascular bundies does not contribute significantly to auxin-induced acidification, is not regulated by auxin, and masks the auxin effect in extracts of whole coleoptile segments. We conclude that auxin-induced acidification in coleoptile segments most often occurs in the nonvascular tissue and is mediated, at least in part, by increased levels of MHA2. 相似文献
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J. M. Zaldivar E. Molga M. A. Al s H. Hern ndez K. R. Westerterp 《Chemical Engineering and Processing: Process Intensification》1995,34(6):543-559
Aromatic nitrations by mixed acid have been selected as a specific case of a heterogeneous liquid-liquid reaction. An extensive experimental programme has been followed using adiabatic and heat-flow calorimetry and pilot reactor experiments, supported by chemical analysis. A series of nitration experiments has been carried out to study the influences of different initial and operating conditions such as temperature, stirring speed and sulphuric acid concentration. In parallel, a mathematical model to predict the overall conversion rate has been developed. In this paper the mathematical modelling and the implementation and experimental validation for benzene, toluene and chlorobenzene mononitration in the kinetic control regime (slow liquid-liquid reaction) are presented and discussed. 相似文献
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M Pan J Suárez de Lezo A Medina M Romero E Hernández J Segura F Melian F Wangüemert M Landin F Benítez M Amat F Velasco A Torres 《Canadian Metallurgical Quarterly》1997,80(10):1336-1338
Two hundred twenty-eight patients with successful coronary stent implantation were randomized either to protamine administration and femoral sheath removal (group I, n = 117) or no heparin neutralization and delayed sheath removal (group II, n = 111). The hospital stay after treatment was shorter in patients receiving protamine; therefore, protamine use for neutralizing circulating heparin may be safely administered immediately after stent implantation. 相似文献
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1. 45 myopes (-3.0 to -6.0 D) were examined before and 1 and 6 months after photorefractive keratectomy (PRK). Visual acuity (VA) was tested using Snellen and logMAR charts. Contrast sensitivity (CS) was measured using a computerized system. 2. Preoperative best corrected VA (BCVA) in myopes was significantly lower in comparison with a control group using logMAR charts only. A reduction of BCVA by both methods at 1. month and its return after 6 months nearly to original values was noted. 3. Significantly lower values of CS were found in patients before PRK compared to the control group. After 1 and 6 months stayed the values on preoperative level. 相似文献
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ADS Expert is an integrated system that (a) provides suggestions about suitable optimization algorithms for a particular structural optimization problem, (b) it offers explanations and guide lines, in the form of hypertext, that refer to the optimization strategy, optimizer and one dimensional search method, (c) it produces the required gradients for the objective function and the constraints using symbolic differentiation, (d) establishes a direct linking with ADS routines and (e) it monitors the evolution of the optimization process. The system can be used as an educational tool for structural optimization and as an efficient integrated system for small to medium size optimization problems for which the objective function and the constraints are given in the form of explicit functions of the design variables. The system is a Windows application and runs quite satisfactorily on PCs. 相似文献
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