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排序方式: 共有698条查询结果,搜索用时 15 毫秒
1.
Annette L. West Louise V. Michaelson Elizabeth A. Miles Richard P. Haslam Karen A. Lillycrop Ramona Georgescu Lihua Han Johnathan A. Napier Philip C. Calder Graham C. Burdge 《Lipids》2021,56(2):229-242
The phospholipid composition of lipoproteins is determined by the specificity of hepatic phospholipid biosynthesis. Plasma phospholipid 20:4n-6 and 22:6n-3 concentrations are higher in women than in men. We used this sex difference in a lipidomics analysis of the impact of endocrine factors on the phospholipid class and molecular species composition of fasting plasma from young men and women. Diester species predominated in all lipid classes measured. 20/54 Phosphatidylcholine (PtdCho) species were alkyl ester, 15/48 phosphatidylethanolamine (PtdEtn) species were alkyl ester, and 12/48 PtdEtn species were alkenyl ester. There were no significant differences between sexes in the proportions of alkyl PtdCho species. The proportion of alkyl ester PtdEtn species was greater in women than men, while the proportion of alkenyl ester PtdEtn species was greater in men than women. None of the phosphatidylinositol (PtdIns) or phosphatidylserine (PtdSer) molecular species contained ether-linked fatty acids. The proportion of PtdCho16:0_22:6, and the proportions of PtdEtn O-16:0_20:4 and PtdEtn O-18:2_20:4 were greater in women than men. There were no sex differences in PtdIns and PtdSer molecular species compositions. These findings show that plasma phospholipids can be modified by sex. Such differences in lipoprotein phospholipid composition could contribute to sexual dimorphism in patterns of health and disease. 相似文献
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MRI fuzzy segmentation of brain tissue using neighborhood attraction with neural-network optimization. 总被引:11,自引:0,他引:11
Shan Shen William Sandham Malcolm Granat Annette Sterr 《IEEE transactions on information technology in biomedicine》2005,9(3):459-467
Image segmentation is an indispensable process in the visualization of human tissues, particularly during clinical analysis of magnetic resonance (MR) images. Unfortunately, MR images always contain a significant amount of noise caused by operator performance, equipment, and the environment, which can lead to serious inaccuracies with segmentation. A robust segmentation technique based on an extension to the traditional fuzzy c-means (FCM) clustering algorithm is proposed in this paper. A neighborhood attraction, which is dependent on the relative location and features of neighboring pixels, is shown to improve the segmentation performance dramatically. The degree of attraction is optimized by a neural-network model. Simulated and real brain MR images with different noise levels are segmented to demonstrate the superiority of the proposed technique compared to other FCM-based methods. This segmentation method is a key component of an MR image-based classification system for brain tumors, currently being developed. Index Terms-Improved fuzzy c-means clustering (IFCM), magnetic resonance imaging (MRI), neighborhood attraction, segmentation. 相似文献
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An increasing number of connectionist models have been proposed to explain behavioral deficits in developmental disorders. These simulations motivate serious consideration of the theoretical implications of the claim that a developmental disorder fits within the parameter space of a particular computational model of normal development. The authors examine these issues in depth with respect to a series of new simulations investigating past-tense formation in Williams syndrome. This syndrome and the past-tense domain are highly relevant because both have been used to make strong theoretical claims about the processes underlying normal language acquisition. The authors conclude that computational models have great potential to advance psychologists' understanding of developmental deficits because they focus on the developmental process itself as a pivotal causal factor in producing atypical phenotypic outcomes. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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An inulin syrup made from Jerusalem artichoke tubers, either in its commercial form or after ultrafiltration, was freeze-dried and used as a prebiotic ingredient in the small-scale manufacture of wafer crackers. The flours used for the preparation of wafer batters were from wheat, rye or spelt wheat, or 1:1 combinations of wheat flour and rye flour or wheat flour and spelt wheat flour. Batter viscosity was strongly influenced by the selection of the flour type, but remained within technologically acceptable limits. The ultrafiltration of the inulin syrup, using a 1 kDa membrane, resulted in a significant reduction of the content of free sugars and minerals which, in turn, had a significant impact on the CIE-Lab color values of the wafer crackers. Using spelt wheat flour instead of wheat flour significantly increased wafer cracker firmness measured by penetration, as did the incorporation of ultrafiltered freeze-dried instead of native freeze-dried Jerusalem artichoke syrup. Sensory analysis revealed a significant influence of product formulation on appearance, flavor and texture of the wafer crackers. It can be concluded from quality scores, which were calculated by using weighting factors assigned to the sensory attributes, that wheat flour may be partially replaced by rye flour or spelt wheat flour without negatively affecting the sensory properties of the wafer crackers. 相似文献
6.
Celin Gürler Mathias Feyen Silke Behrens Nina Matoussevitch Annette M. Schmidt 《Polymer》2008,49(9):2211-2216
Much effort is conducted to construct artificial objects that are capable of converting chemical or electromagnetic energy into a specific, predetermined motion on the nanoscale. We present results on the synthesis of core–shell nanoparticles capable to be set in rotation by the application of electromagnetic fields. The nanorotors implied in the study are based on the cobalt nanospheres decorated with a stabilizing brush shell composed of poly(?-caprolactone) that is attached by surface-initiated polymerization. The functional cores used as macroinitiators can be fabricated alternatively by a two-step or a one-step process. 相似文献
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Three training methods to improve attention management skills in process control were compared. Forty students from technical disciplines participated in a five-hour module of emphasis shift training (EST), EST combined with situation awareness training (EST/SA), and drill and practice (D&P) on a simulated process control task. Participants were then tested three times for 45 min each (immediately after training, two weeks after training, and six weeks after training) for system control performance and diagnostic performance on familiar and nonfamiliar fault states. D&P led to superior diagnostic performance on familiar system faults. EST/SA training supported the diagnosis of novel system faults. EST was less effective than expected for system control performance. Implications for training design in process control are discussed. 相似文献
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This 6-year longitudinal study examined girls' peer-nominated social preference and aggression in childhood as predictors of self- and parent-reported externalizing symptoms, substance use (i.e.. cigarette, alcohol, and marijuana use), and sexual risk behavior in adolescence. Participants were 148 girls from diverse ethnic backgrounds, who were initially assessed in Grades 4-6 and again in Grades 10-12. Results supported a moderator model, indicating that social preference changed the nature of the association between childhood aggression and adolescent outcomes. When accompanied by peer rejection, aggressive behavior was moderately stable over time and significantly associated with adolescent girls' substance use and sexual risk behavior. However, under conditions of peer acceptance, no significant association between childhood aggression and adolescent outcomes emerged. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Annette Evans Vladimir Strezov Tim J. Evans 《Renewable & Sustainable Energy Reviews》2012,16(6):4141-4147
Renewable energy technologies are expected to take the leading role in the forthcoming energy generation portfolio in order to achieve sustainable energy generation. The major constraints for increasing penetration of renewable energy sources is their availability and intermittency, which can be addressed through energy storage when available and energy use when needed. This work reviews the energy storage technologies and gives an up to date comparative summary of the performance parameters of the major energy storage options. The parameters compared here include efficiency, energy capacity, energy density, run time, capital investment costs, response time, lifetime in years and cycles, self discharge and maturity of each energy storage option. The choice of storage system will depend on individual requirements, and may even incorporate more than one energy storage system to increase the energy storage capacity and improve energy security. 相似文献