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1.
C. A. Pineda P. Wenzl J. Mayer J. Mesjasz-Przybylowicz W. J. Przybylowicz V. M. Prozesky 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1997,130(1-4):362-367
A Brachiaria breeding project is being conducted at CIAT, Colombia to combine acid soil adaptation of B. decumbens with other favourable traits of Brachiaria species that are less adapted to acid soils. Micro-PIXE was applied to investigate nutrient uptake and distribution in root tips of different species grown in hydroponic culture under control and simulated acid soil stress conditions. Different sample measurement approaches were evaluated, including: (1) linear scans with single point measurements along the root axis; (2) mapping of whole root tips; and (3) mapping of root cross sections. Different tissue types could be distinguished on the base of differences in nutrient concentrations and/or Al stress. Al, if supplied under nutrient stress conditions, increased P accumulation in the central vascular tissue of the meristematic and elongation zone of B. decumbens and B. brizantha. Furthermore, a negative correlation was found between Al and Cl accumulation in the root cap of B. decumbens. 相似文献
2.
3.
This study demonstrates that the use of high field 1H NMR spectroscopy permits individual detection of phosphatidylcholine and sphingomyelin molecules at the surface of native low density lipoprotein (LDL) particles. Distinct behaviour was observed for the choline head group -N(CH3)3 resonances of these different phospholipids revealing preferential immobilisation for phosphatidylcholine. This suggests the existence of reversible and irreversible phosphatidylcholine-apolipoprotein B interactions and is consistent with microdomain formation at the surface monolayer of LDL. The novel resonance assignment and results show that 1H NMR can provide efficient and practical means for future studies on the structure and dynamics at the LDL surface. 相似文献
4.
Ten groups of 14 immunosuppressed NMRI-mice (nu/nu) were raised and kept under germ-reduced conditions. The control animals were fed a germ-reduced diet, nine other groups received the same diet with selegiline (CAS 14611-51-9, Deprenyl) or lipoic acid (thioctic acid, CAS 62-46-4) admixed at various amounts. The 50% survival rate, the total life span of each group and the areas under the curves were determined to evaluate life expectancy as compared to the controls. The racemate of lipoic acid at high dosage (350 mg/kg body weight) reduced the life span significantly. The S(-)-enantiomer of lipoic acid (75 mg/kg body weight) increased the 50% survival rate, whereas the physiologic R(+)-enantiomer (9 mg/kg body weight) expanded the total life span of its group. Alteration of only one out of three parameters was not considered significant. All other groups except for one did not differ from controls: only animals which obtained 75 micrograms selegiline per kg of body weight and per day exerted increased life expectancies by all three parameters. This group exhibited also in statistical evaluation a significantly (p < 0.05) prolongated survival time up to about 200% as compared to the control animals. 相似文献
5.
DI Timokhin AV Istomin TS Shushkova TG Voronel' IG Mikha?lov 《Canadian Metallurgical Quarterly》1997,(2):19-21
Based on generalization and analysis of instructions and guidelines for therapeutical and prophylactic diets of workers, ways of its optimization were proposed, by using bifide-containing acid dairy products as a preventive agent against possible occupational diseases caused by occupational factors. 相似文献
6.
Cancer statistics, 1993 总被引:1,自引:0,他引:1
7.
C Serveau L Juliano P Bernard T Moreau R Mayer F Gauthier 《Canadian Metallurgical Quarterly》1994,76(2):153-158
A discontinuous borate/formate buffer system is presented for horizontal polyacrylamide gel electrophoresis of DNA fragments. The resolution potential of the system could be altered by changing the total monomer concentration (5-9%T), the concentration of the crosslinker piperazine diacrylamide (2-5%CPDA), as well as the concentration of formate in the gel (40-120 mM), the leading ion of the buffer system. The separation of DNA fragments would be improved by increasing the migration distance from 22 to 28 cm. This discontinuous polyacrylamide gel electrophoresis system proved highly reproducible. 相似文献
8.
Volker Mayer 《Dynamical Systems: An International Journal》2007,22(2):169-178
We prove several essential fractal properties, such as positivity, finiteness or local infinity, of Hausdorff and packing measures of radial Julia sets for large subclasses of entire and meromorphic functions considered in our previous work: çGeometric thermodynamical formalism and real analyticity for meromorphic functions of finite order'. Most of the results proven are shown to be optimal. 相似文献
9.
M. J. Caton J. W. Jones H. Mayer S. Stanzl-Tschegg J. E. Allison 《Metallurgical and Materials Transactions A》2003,34(1):33-41
An investigation of the fatigue properties of cast W319-T7, an Al-Si-Cu alloy used in automotive engine components, was conducted
using ultrasonic testing equipment with operating frequencies of 20 kHz. The stress-life (S-N) behavior at room temperature
was determined for three solidification conditions of this alloy, where stresses for fatigue lives ranging from 105 to 109 cycles were determined. The results are compared to fatigue data acquired using servohydraulic equipment operating at 40
Hz. No influence of loading frequency has been observed. A discrete endurance limit is indicated for each of the three solidification
conditions of W319-T7. The scientific and practical implications of this result are discussed. A material model presented
previously is modified by introducing a crack growth threshold condition in order to predict the observed endurance limits.
The model is shown to effectively predict the influence of solidification time on the fatigue properties of W319-T7. 相似文献
10.
It is proposed that when solving an arithmetic word problem, unsuccessful problem solvers base their solution plan on numbers and keywords that they select from the problem (the direct translation strategy), whereas successful problem solvers construct a model of the situation described in the problem and base their solution plan on this model (the problem-model strategy). Evidence for this hypothesis was obtained in 2 experiments. In Experiment 1, the eye fixations of successful and unsuccessful problem solvers on words and numbers in the problem statement were compared. In Experiment 2, the degree to which successful and unsuccessful problem solvers remember the meaning and exact wording of word problems was examined. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献