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排序方式: 共有1377条查询结果,搜索用时 31 毫秒
91.
Jakub Adam Koza Margitta Uhlemann Annett Gebert Ludwig Schultz 《Electrochimica acta》2008,53(27):7972-7980
The effect of an uniform magnetic field with a flux density up to 1 T and different configurations relative to the electrode surface on the electrocrystallization of Fe on polycrystalline Au(1 1 1) from acidic sulphate electrolyte has been investigated. It was found, irrespective of the applied parameters, that the deposition proceeds through successive nucleation and growth steps. The first one related to 2D growth was followed by a second nucleation and 3D diffusion controlled growth. At potential of −1500 and −1550 mVMSE nucleation proceeds via a progressive mode, while at −1650 mVMSE it follows an instantaneous mode. A strong influence of the parallel-to-electrode magnetic field on the nucleation processes was found for the progressive mode, which leads to the increase of the growth rate and as a consequence to retardation of the nucleation rate of the 3D step. Additionally, in this configuration at a sufficiently high magnetic flux density a third nucleation step could be observed (3D), which was found to be also affected by a magnetic field. No effect of a perpendicular-to-electrode magnetic field on the nucleation has been observed. The effects of a magnetic field on the nucleation and growth processes are discussed with respect to the magnetohydrodynamic effect (MHD) and confirmed by rotating disc electrode (RDE) experiments. 相似文献
92.
This study was designed to draw on clinical practice as a way of identifying priority areas for child and adolescent psychotherapy research. 1,162 psychologists and psychiatrists described several features of their clinical work and evaluated the effects of alternative treatment approaches, factors that influence therapeutic change, and the priority of alternative types of research. The majority agreed on (a) the importance of several specific child, parent, and therapist factors that contribute to outcome; (b) the utility and effectiveness of alternative treatment approaches; and (c) the high priority of research on therapeutic processes and matching cases to alternative types of treatments. In general, the factors, treatments, and types of studies identified have rarely been examined empirically. The use of practitioner views to identify lines of research may aid not only in reducing the hiatus between research and practice but also in placing clinical work on a stronger empirical footing. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
93.
MA‐NOTMP: A Triazacyclononane Trimethylphosphinate Based Bifunctional Chelator for Gallium Radiolabelling of Biomolecules 下载免费PDF全文
Sophie Poty Dr. Pauline Désogère Dr. Jakub Šimeček Dr. Claire Bernhard Dr. Victor Goncalves Dr. Christine Goze Dr. Frédéric Boschetti Dr. Johannes Notni Prof. Dr. Hans J. Wester Prof. Dr. Franck Denat 《ChemMedChem》2015,10(9):1475-1479
In the past few years, gallium‐68 has demonstrated significant potential as a radioisotope for positron emission tomography (PET), and the optimization of chelators for gallium coordination is a major goal in the development of radiopharmaceuticals. Methylaminotriazacyclononane trimethylphosphinate (MA‐NOTMP), a new C‐functionalized triazacyclononane derivative with phosphinate pendant arms, presents excellent coordination properties for 68Ga (low ligand concentration, labelling at low pH even at room temperature). A “ready‐to‐be‐grafted” bifunctional chelating agent (p‐NCS‐Bz‐MA‐NOTMP) was prepared to allow 68Ga labelling of sensitive biological vectors. Conjugation to a bombesin(7–14) derivative was performed, and preliminary in vitro experiments demonstrated the potential of MA‐NOTMP in the development of radiopharmaceuticals. This new chelator is therefore of major interest for labelling sensitive biomolecules, and further in vivo experiments will soon be performed. 相似文献
94.
Inclusion of flaxseed in turkey diets decreases the n‐6/n‐3 PUFA ratio and increases the proportion of biologically active EPA and DHA without affecting meat quality 下载免费PDF全文
95.
Sean Poust James Piety Dr. Arren Bar‐Even Dr. Catherine Louw Prof. Dr. David Baker Prof. Dr. Jay D. Keasling Prof. Dr. Justin B. Siegel 《Chembiochem : a European journal of chemical biology》2015,16(13):1950-1954
An enzyme that catalyzes the formose reaction, termed “formolase”, was recently engineered through a combination of computational protein design and directed evolution. We have investigated the kinetic role of the computationally designed residues and further characterized the enzyme's product profile. Kinetic studies illustrated that the computationally designed mutations were synergistic in their contributions towards enhancing activity. Mass spectrometry revealed that the engineered enzyme produces two products of the formose reaction—dihydroxyacetone and glycolaldehyde—with the product profile dependent on the formaldehyde concentration. We further explored the effects of this product profile on the thermodynamics and yield of the overall carbon assimilation from the formolase pathway to help guide future efforts to engineer this pathway. 相似文献
96.
The development of motion capturing devices poses new challenges in the exploitation of human‐motion data for various application fields, such as computer animation, visual surveillance, sports, or physical medicine. Recently, a number of approaches dealing with motion data have been proposed, suggesting characteristic motion features to be extracted and compared on the basis of similarity. Unfortunately, almost each approach defines its own set of motion features and comparison methods; thus, it is hard to fairly decide which similarity model is the most suitable for a given kind of human‐motion retrieval application. To cope with this problem, we propose the human motion model evaluator, which is a generic framework for assessing candidate similarity models with respect to the purpose of the target application. The application purpose is specified by a user in form of a representative sample of categorized motion data. Respecting such categorization, the similarity models are assessed from the effectiveness and efficiency points of view using a set of space‐complexity, information‐retrieval, and performance measures. The usability of the framework is demonstrated by case studies of three practical examples of retrieval applications focusing on recognition of actions, detection of similar events, and identification of subjects. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
97.
Adam C. Siegel Scott T. Phillips Michael D. Dickey Nanshu Lu Zhigang Suo George M. Whitesides 《Advanced functional materials》2010,20(1):28-35
This paper describes several low‐cost methods for fabricating flexible electronic circuits on paper. The circuits comprise i) metallic wires (e.g., tin or zinc) that are deposited on the substrate by evaporation, sputtering, or airbrushing, and ii) discrete surface‐mountable electronic components that are fastened with conductive adhesive directly to the wires. These electronic circuits—like conventional printed circuit boards—can be produced with electronic components that connect on both sides of the substrate. Unlike printed circuit boards made from fiberglass, ceramics, or polyimides, however, paper can be folded and creased (repeatedly), shaped to form three‐dimensional structures, trimmed using scissors, used to wick fluids (e.g., for microfluidic applications) and disposed of by incineration. Paper‐based electronic circuits are thin and lightweight; they should be useful for applications in consumer electronics and packaging, for disposable systems for uses in the military and homeland security, for applications in medical sensing or low‐cost portable diagnostics, for paper‐based microelectromechanical systems, and for applications involving textiles. 相似文献
98.
E. Bruce Nauman Mathew Armstrong Jakub Horak 《Chemical Engineering and Processing: Process Intensification》2010
Conventional static mixers typically require high length to diameter ratios to be effective. This paper considers static mixers design to increase first appearance times in short, fat reactors. Three types are considered: conical baffles and annular baffles for tubular reactors and axial baffles for reactors with a rectangular cross-section. Relatively simple designs allow production increases (or reactor volume decreases) on the order of 20–50%. 相似文献
99.
Aluminum control of phosphorus sorption by lake sediments 总被引:9,自引:0,他引:9
Kopácek J Borovec J Hejzlar J Ulrich KU Norton SA Amirbahman A 《Environmental science & technology》2005,39(22):8784-8789
Release of reactive (phosphate-like) phosphorus (P) from freshwater sediments represents a significant internal P source for many lakes. Hypolimnetic P release occurs under reducing conditions that cause reductive dissolution of ferric hydroxide [Fe(OH)3]. This hypolimnetic P release may be naturally low or artificially reduced by sediment with naturally high or artificially elevated concentrations of aluminum hydroxide [Al(OH)3]. We presentfield and laboratory data for a common extraction analysis of sediments from 43 lakes differing in trophic status, pH regime, climate, and P loading. The results indicate that a simple sequential extraction of sediment may be a useful predictor of sediment's ability to release P. Sequential extractions of sediment P, Al, and Fe by water (H2O), bicarbonate-dithionite (BD), and NaOH (at 25 degrees C) showed that negligible amounts of P would be released from lake sediments during hypolimnetic anoxia if either (1) the molar Al(NaOH-25):Fe(BD) ratio is > 3 or (2) the molar Al(NaOH-25):P(H2O+BD) ratio is > 25. These ratios can be used as operational targets for estimation of sediment P release potential and Al dosing of P-rich sediment to prevent hypolimnetic P release under anoxic conditions. 相似文献
100.
Y. Kalachyova O. Lyutakov V. Prajzler J. Tuma J. Siegel V. vor
ík 《Polymer Composites》2014,35(4):665-670
The aging of thin polymer films is interesting for the development of nonlinear optical media. In this study, the optical properties of porphyrin‐doped poly(methylmethacrylate) (PMMA) films are investigated before and after annealing. Both absorption and luminescence spectroscopies were used to characterize the changes that occurred during the thermal treatment. The surface and bulk characteristics of the doped films were also measured using atomic force microscopy, X‐ray‐induced photoelectron spectra, and DSC. We found that the aging of the thin polymer films led the porphyrin molecules to diffuse in the direction of the polymer surface. This led to the random formation of porphyrin aggregates on the surface, followed by absorption band shift and little luminescence quenching. These results suggest that porphyrin‐doped PMMA films could be used as long‐term stable active optical materials. POLYM. COMPOS., 35:665–670, 2014. © 2013 Society of Plastics Engineers 相似文献