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排序方式： 共有5965条查询结果，搜索用时 15 毫秒
71.
Jian Wang Angel D. Gonzalez Victor M. Ugaz 《Advanced materials (Deerfield Beach, Fla.)》2008,20(23):4482-4489
72.
Victor Wessels Gwénaël Le Mené Stefan F. Fischerauer Tanja Kraus Annelie‐Martina Weinberg Peter J. Uggowitzer Jörg F. Löffler 《Advanced Engineering Materials》2012,14(6):B357-B364
A study of Mg‐based bulk metallic glasses (BMGs) as biodegradable bone implants is presented. The implantation site can affect performance, so the BMGs were evaluated in vivo in rat femurs using µ‐CT scans at various times for more than 90 days. Estimates of H2 evolution correlate well with previous in vitro studies and bone–implant contact is similar to that for Ti pins. One potential drawback of Mg‐based BMGs in this application is embrittlement due to structural relaxation. Here, relaxation at 20 and 37 °C is examined, and an increase in the characteristic relaxation time, from 10 to 30 days at 20 °C, is observed as Zn increases from 29 to 32 at.%, correlating with dramatically reduced hydrogen evolution. 相似文献
73.
Victor D. Fachinotti Steven Le Corre Nicolas Triolet Manuel Bobadilla Michel Bellet 《International journal for numerical methods in engineering》2006,67(10):1341-1384
As an approach towards a better modelling of solidification problems, we introduce a thermo‐mechanical and macrosegregation model that considers a solidifying alloy as a binary mixture made of a liquid and a solid phase. Macroscopic conservation laws for mass, momentum and solute are obtained by spatial averaging of the respective microscopic conservation equations. Assuming local thermal equilibrium, a single equation for the conservation of the mixture energy is then written. A single equation can be obtained for the solute as well by invoking a proper microsegregation rule. The numerical implementation in a two‐dimensional finite element code is then detailed. Lastly, some examples of simulations of academic tests as well as industrial applications for continuous casting of steel slabs are discussed. They particularly enlighten the ability of the formulation to describe the formation of central macrosegregation during the secondary cooling of slab continuous casting processes. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
74.
Diarrhea is a non-specific symptom which may be associated with Addison's disease and several causes had been demonstrated in the aetiology. We describe a patient with Addison's disease who was suffering from chronic diarrhea for three months. She was diagnosed as having collagenous colitis and successfully treated with Sulphasalazine, 2 g/day. Collagenous colitis is an uncommon cause of chronic diarrhea and the association of collagenous colitis with Addison's disease has not previously been described. We think that collagenous colitis may play a role in the aetiology of diarrhea in patients with Addison's disease and therefore we suggest a full colonoscopic examination in other patients with Addison's disease and diarrhea to determine the incidence of collagenous colitis in the aetiology of diarrhea. 相似文献
75.
An alignment of all PPi-dependent phosphofructokinases and all allosteric ATP-dependent PFKs shows relatively few residues that are fully conserved. One residue that is conserved is a methionine residue that appears from the crystal structure of Escherichia coli PFK to be interacting with fructose 6-P. Very conservative substitutions for this methionine with leucine or isoleucine by site-directed mutagenesis of E. coli ATP-PFK and Entamoeba histolytica PPi-PFK produced profound decreases either in the apparent affinity for fructose 6-P or in maximal velocity, or both. Methionine provides a highly specific interaction with fructose 6-P for binding and for transition state stabilization. 相似文献
76.
77.
78.
RG Wilde JT Billheimer SJ Germain EA Hausner PC Meunier DA Munzer JK Stoltenborg PJ Gillies DL Burcham SM Huang JD Klaczkiewicz SS Ko RR Wexler 《Canadian Metallurgical Quarterly》1996,4(9):1493-1513
Acyl-CoA:cholesterol acyltransferase (ACAT) is the enzyme largely responsible for intracellular cholesterol esterification. A systemic inhibitor of ACAT is believed to be able to slow or even reverse the atherosclerotic process. Towards that goal, a series of cyclic sulfides, derived from the hetero-Diels-Alder reaction of thioaldehydes with 1,3-dienes, and bearing carboxamide substituents, were prepared and evaluated for in vitro (in several tissues and species) and ex vivo ACAT inhibition. Minor changes in subsequent structure were found to have a significant effect in optimization of the biological activity of this series of compounds. 相似文献
79.
AJ Miller RG Leisure VA Mashkov FL Galeener 《Canadian Metallurgical Quarterly》1996,53(14):R8818-R8820
80.
RG Jaeger PT de Oliveira MM Jaeger VC de Araújo 《Canadian Metallurgical Quarterly》1997,84(6):663-667
BACKGROUND: Endoscopic sclerotherapy (ST), widely used as treatment of bleeding esophageal varices, might cause motility disturbances of the esophagus as well as mucosal damage. We performed this study to evaluate the long-term effects of repeated sclerotherapy on esophageal motility and mucosa. METHODS: Ten patients with liver cirrhosis and bleeding esophageal varices treated with repeated ST were evaluated after the last ST, median 52 months, by esophageal manometry and gastroscopy where forceps biopsies were taken. RESULTS: We found a significant difference in the distal esophageal sphincter intraabdominal length. The distal esophageal sphincter pressure was somewhat lower in the ST group although the difference did not reach statistical significance. There was infiltration of neutrophil leukocytes in biopsies from four patients and normal findings in the rest. CONCLUSIONS: Long-term follow-up evaluation showed statistically longer distal esophageal intraabdominal length in the ST group. No mucosal alterations were found at the histopathological investigation. 相似文献