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The microstructure and crystallization behaviour of melt-spun Al88Ni9Ce2Fe1 amorphous alloy and nanophase composites have been studied by means of X-ray diffraction, transmission electron microscopy and scanning and isothermal calorimetry. The diffraction patterns from Al88Ni9Ce2Fe1 amorphous alloys are diffuse, indicating a basically amorphous structure but contain two rings presumed to be associated with quenched-in nuclei. In the cases of Al88Ni9Ce2Fe1 nanophase composites, nanoscale precipitated particles are homogeneously dispersed in an amorphous matrix, and the crystallite diameter and volume fraction are sensitive to quenching conditions. During thermal crystallization, a two-step phase transformation occurs in the amorphous alloy and nanocomposites, which is characterized by a diffusion-controlled precipitation of nanoscale Al particles and the growth of a Al3(Ni, Fe) nanophase prior to a Al11Ce3 nanophase. This study gives insight into structure-control for obtaining nanophases dispersed in an amorphous matrix by rapid quenching. 相似文献
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J. Hou;J. Long;J. Xiang;W. Pan;D. Li;X. Liu; 《British journal of psychology (London, England : 1953)》2024,75(5):1182-1192
To analyse the correlation between the intestinal microbiota (IM) and differential development of Quasipaa spinosa across different stages of metamorphosis, we focused on four key developmental periods (15 days post-hatch [dph; Gosner stage, GS23], 60 dph [GS25], 90 dph [GS41] and 150 dph [GS25, GS41, GS42, GS46]) and used 16S rDNA amplicon sequencing. Results showed that IM diversity in Q. spinosa was related to life history. Specifically, there was a significant difference between the aquatic and terrestrial stages, and IM diversity increased with age. Proteobacteria, Bacteroidetes and Firmicutes were the dominant phyla in tadpoles, whereas Bacteroidetes, Proteobacteria, Firmicutes and Fusobacteria were the dominant phyla at the metamorphosis stages. The composition of the IM at different stages and ages varied considerably, but the changes were not substantial among different development stages at 150 dph. This was probably because age has a greater influence than growth factors, and host selective pressure increases with age. This study provides a theoretical reference for subsequent studies on the IM, as well as for the prevention of amphibian endogenous pathogenic microbial diseases. 相似文献
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Ran MS Xiang MZ Mao WJ Hou ZJ Tang MN Chen EY Chan CL Yip PS Conwell Y 《Suicide & life-threatening behavior》2005,35(6):694-701
In this study, demographic and clinical characteristics of individuals with schizophrenia in a Chinese rural community who had attempted suicide at some time in their lives and those who had not made a suicide attempt were compared. Among individuals with schizophrenia, subjects with (n = 38) and without (n = 472) a lifetime history of suicide attempt were assessed with the Present State Examination. The results indicate that attempters had a significantly younger age, higher level of education, higher rate of lifetime depressed mood and hopelessness, and a larger number of positive symptoms than patients without suicide attempts. The logistic regression models also indicated that hopelessness, the number of positive symptoms and age were the most important predictors. Early interventions focusing on reducing hopelessness and controlling positive symptoms may help reduce the risk of suicide attempts among patients with schizophrenia. 相似文献
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How accurate are children when dating very long-term memories? Chinese and European Canadian 8-, 11-, and 14-year-olds (N=344) recalled and dated memories from before they went to school in a memory fluency task. Parents provided verification of children's memories and age estimates. Across all age and culture groups, a telescoping effect (i.e., events were dated as taking place more recently than they actually did) was found for earlier memories (before 48 months) and a reverse telescoping effect for later memories (after 48 months). Older children showed a greater tendency to telescope earlier memories and a weaker tendency to reverse telescope later memories than did younger children. Euro-Canadian children showed larger reverse telescoping than Chinese children. These are the first systematic findings concerning the accuracy of children's dating of very long-term memories. They shed new light on the phenomenon of telescoping and have implications for research on childhood amnesia. 相似文献
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The primary purpose of this study was to investigate whether the theory of planned behavior (TPB) mediated the relationship between dialectical thinking and health behaviors. A sample of 285 undergraduates was tested with a dialectical thinking styles scale, health promoting lifestyle profiles, and TPB questionnaires. Structural equation modeling was used for data analysis. Results indicated that all the three dimensions of thinking styles (belief in the connection, acceptance of change, and acceptance of contradiction) exerted significant effects on TPB constructs. Specifically, the connection and the change dimensions had positive effects on health behaviors mediated by TPB, whereas the contradiction dimension had a negative effect. Model 2 showed a satisfactory fit, demonstrating the influential pathways between dialectical thinking and health behaviors. Implications in issues of health promotion and future research are discussed. 相似文献
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In this study, we aimed to explore the impact of self-efficacy on depression – specifically, to test and verify the mediating role of dispositional optimism between the two variables. Five hundred and thirty-five undergraduates from two universities were recruited and given a Self-Efficacy Questionnaire, Revised Life Orientation Test, and Self-Rating Depression Scale. Results indicated that there are indeed significant relationships among self-efficacy, dispositional optimism, and each identified dimension of depression; structural equation modeling showed that the relationship between self-efficacy and depression is partially mediated by dispositional optimism. To this effect, we concluded that to develop and improve students’ self-efficacy will reduce their levels of depression, which may have implications in college counseling. 相似文献
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