首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
The atomic structure of {1?1?2} twin boundary in a specialty β-Ti alloy, gum metal, has been studied by means of conventional transmission electron microscopy, bright-field and high-angle annular dark field scanning transmission electron microscopy imaging. The observations provide direct evidence that the {1?1?2} twin boundary has a complex, multiple-layer structure, which is composed of various structural units. These structural units are formed as a result of different degrees of inner atomic-column shifting. The complex structure of the {1?1?2} twin boundary is different to the atomic structure of the previously reported ω phase.  相似文献   

2.
Abstract

Two unexpected features have been revealed by transmission electron microscopy investigations of deformed silicon bicrystals: (a) slip of a/2 〈110〉 dislocations on {001} planes and (b) non-dissociation of Lomer–Cottrell dislocations formed by intersecting slip dislocations.  相似文献   

3.
4.
Measurements of static permittivity, refractive index and density have been carried out to study possible H-bonded complexes in solutions of anisole diluted by benzene together with high-static-permittivity alcohols, i.e. cyclohexanol, n-butanol, tert-butanol, isopropyl alcohol and 1-hexanol. The experiments were performed at 303 K. Dipole moments of the mixtures are calculated from the experimental data and these are used to obtain dipolar increments. The concentration ratio of proton donor to proton acceptor is plotted against a parameter, ΩB, which is determined from experimental data. From the plot, the dipole moment of the mixture and that of the component B are determined. The order of the complex can be obtained from the nature of the graph. The investigation shows that the interaction between the two components arises solely from a polarization effect.  相似文献   

5.
Abstract

High-resolution transmission electron microscopy has been used to image the atomic structure of the (2S2)γ austenite-martensite interface. By imaging along [101]γ ∥[111]α, the interface was viewed edge-on and seen to consist of facets on the close-packed (111)γ, planes. From the correspondence of atoms in the close-packed planes across the austenite-martensite interface, the magnitude of the shear can be analysed as (a/24)<112> on every close-packed plane in the plane of projection. Comparison with theory indicates that this is an (a/12)<112> Burgers vector out of the plane of projection. Hence, each atomic facet can be viewed as a structural ledge containing an (a/12)<112> transformation dislocation.  相似文献   

6.
In this study, in order to describe fully the impact of Western scholarship, we first explore the Western-oriented study of religion in Turkey. Secondly, by making special reference to the treatment of the foreign vocabulary of the Qur'¯n by Turkish intellectuals, we investigate the extent of Western influence in the first half of the twentieth century. Thirdly, considering an institutional attempt to understand Western academia, we discuss Zeki Velidi Togan and the Institute of Islamic Studies (established in 1953). Fourthly, we examine the relationship between Western-oriented studies of religion and the classical study of Islam in Turkey, explaining the polemical nature of these studies in Turkish academic circles. The Turkish treatment of the Bible and the Turkish evaluation of the Western treatment of the Qur'¯n will provide case studies. The last part of the work discusses recent developments in Turkish scholarship dealing with the application of modern critical and linguistic methods to the Qur'¯n.  相似文献   

7.
8.
In our view, the ability to impose moral values which may be, to some extent, either shared or conflictual, influences the strategy adopted when writing argumentative texts. Our hypothesis is that the greater the socio-moral distance between the writers’ representations (the writers in this case being children) and those of the recipients (here the parents), the more likely it is that writing will be successful. Three topics derived from a preliminary experiment and corresponding to significant differences in opinion between children and parents were tested in a population of 11-year-old pupils. The pupils had to write a letter designed to convince their parents about one of these topics. We analyzed the texts in order to identify the different configurations in the frequencies of use of the pronouns (frequencies of Je (I), Tu (You), Il (He), On (One/We)) and adverbs. These frequencies differed depending on the topic that was being written about (the moral context that is mobilized).
Emmanuèle AuriacEmail: Email:
  相似文献   

9.
This longitudinal study investigated differences in beliefs and perceived behavioural control between smokers and non-smokers in a large sample of adolescents. Positive and negative instrumental beliefs, normative beliefs, perceived behavioural control (PBC) and smoking status were assessed in the same participants at 11, 13 and 15 years of age. Prospective analyses among non-smokers revealed that for boys, negative instrumental beliefs in non-smokers at age 11 predicted smoking at age 15 years. For girls, normative beliefs and PBC in non-smokers at age 11 predicted smoking status at age 13; normative beliefs at age 11 predicted smoking at age 15; and positive instrumental beliefs and normative beliefs at age 13 predicted smoking status at age 15. Cross-sectional data revealed that smokers were significantly more likely than non-smokers to endorse positive instrumental beliefs, less likely to agree with negative instrumental belief items, more likely than non-smokers to perceive social pressure to smoke, and less likely to report control over smoking, and that female smokers reported less control over smoking and fewer negative instrumental beliefs than all other groups including male smokers at age 13. The need for belief-based preventative interventions that are age- and gender-relevant is discussed.  相似文献   

10.
Developmental studies have demonstrated that cognitive processes such as attention, suppression of interference and memory develop throughout childhood and adolescence. However, little is currently known about the development of top-down control mechanisms and their influence on cognitive performance. In the present study, we used functional magnetic resonance imaging to investigate modulation of activity in the ventral visual cortex in healthy 7–11-year-old children and young adults. The participants performed tasks that required attention to either face (Fs task) or scene (Sf task) images while trying to ignore distracting scene or face images, respectively. A face-selective area in the fusiform gyrus (fusiform face area, FFA) and an area responding preferentially to scene images in the parahippocampal gyrus (parahippocampal place area, PPA) were defined using functional localizers. Children responded slower and less accurately in the tasks than adults. In children, the right FFA was less selective to face images and regulation of activity between the Fs and Sf tasks was weaker compared to adults. In the PPA, selectivity to scenes and regulation of activity, there according to the task demands were comparable between children and adults. During the tasks, children activated prefrontal cortical areas including the middle (MFG) and superior (SFG) frontal gyrus more than adults. Functional connectivity between the right FFA and left MFG was stronger in adults than children in the Fs task. Children, on the other hand, had stronger functional connectivity than adults in the Sf task between the right FFA and right PPA and between right MFG and medial SFG. There were no group differences in the functional connectivity between the PPA and the prefrontal cortex (PFC). Together the results suggest that, in 7–11-year-old children, the FFA is still immature, whereas the selectivity to scenes and regulation of activity in the PPA is comparable to adults. The results also indicated functional immaturity of the PFC in children compared to adults and weaker connectivity between the PFC and the rFFA, explaining the weaker regulation of activity in the rFFA between the Fs and Sf tasks.  相似文献   

11.
Gender differences regarding aggressive behaviour were investigated in 167 school children, 11 to 12 years of age, through peer-rating techniques supported by self-ratings and interviews. The social structure of the peer groups also was studied. The principal finding was that girls made greater use of indirect means of aggression, whereas the boys tended to employ direct means. Gender differences in verbal aggression were less pronounced. The social structure of peer groups was found to be tighter among girls, making it easier for them to exploit relationships and harm their victims by indirect manipulative aggression. Because indirect aggression has rarely been satisfactorily studied with tests of aggression, this finding may help to explain 1) the generally lower correlation found between peer-rated and self-rated aggression in girls than among boys (indirect means not being so readily recognized by the subject as a kind of aggression) and 2) the low stability of aggressiveness in girls often found in developmental studies.  相似文献   

12.
13.
14.
Brain imaging studies have identified two cortical areas, the parahippocampal place area (PPA) and the retrosplenial complex (RSC), that respond preferentially to the viewing of scenes. Contrary to the PPA, little is known about the functional maturation and cognitive control of the RSC. Here we used functional magnetic resonance imaging and tasks that required attention to scene (or face) images and suppression of face (or scene) images, respectively, to investigate task-dependent modulation of activity in the RSC and whole-brain functional connectivity (FC) of this area in 7–11-year-old children and young adults. We compared responsiveness of the RSC with that of the PPA. The RSC was selectively activated by scene images in both groups, albeit less than the PPA. Children modulated activity between the tasks similarly in the RSC and PPA, and to the same extent as adults in PPA, whereas adults modulated activity in the RSC less than in PPA. In children, the whole brain FC of the RSC was stronger in the Sf than Fs task between the left RSC and right fusiform gyrus. The between groups comparison suggested stronger FC in children than adults in the Sf task between the right RSC and the left inferior parietal lobule and intraparietal sulcus. Together the results suggest that the function of the RSC and the related networks undergo dynamic changes over the development from 7–11-year-old children to adulthood.  相似文献   

15.
The structure and development of executive functioning (EF) have been intensively studied in typically developing populations, with little attention given to those with Special Educational Needs (SEN). This study addresses this by comparing the EF structure of 132 adolescents (11–14 years-old) with SEN and 138 adolescents not requiring additional support (Non-SEN peers). Participants completed verbal and non-verbal assessments of key components of EF: inhibition, working memory and switching. Confirmatory Factor Analysis on each group tested one-, two- and three-factor models of EF. In both groups, there was statistical support for the fit of one- and two-factor models with no model being clearly better than the others; there was little support for three-factor models. Parsimony suggests that the one-factor model best represents the structure of EF. In light of our results, the implications for the nature of EF in early adolescence in both SEN and Non-SEN groups are discussed.  相似文献   

16.
17.

The atomic structure and chemical composition of a =3, [110]/{111} symmetric tilt grain boundary in an yttria-stabilized cubic zirconia bicrystal has been investigated by high-resolution transmission electron microscopy (HRTEM) and nanoprobe energy-dispersive X-ray spectroscopy. The experimental HRTEM images are compared with simulated images for a model obtained by lattice statics calculations. It is found that the grain boundary has two individual mirror symmetrical planes in cation and anion sublattices. In this case, the cations are forced to form sevenfold coordination in the vicinity of the boundary owing to the restraint of the boundary structure, while the cations in the cubic fluorite structure have eightfold coordination. The segregation of yttrium ions was experimentally detected at the = 3 boundary, a finding that is considered to be closely related to the change in the local coordination at the boundary.  相似文献   

18.
This study aimed to examine longitudinal developmental patterns in the daily amounts of screen time and technoference in infants aged 2, 4, 7, and 11 months and to examine associations with maternal sociodemographic factors across all age groups.The results showed that the amount of screen time varied between 6 and 17 min a day, while interruptions in mother-infant interactions due to maternal use of digital technology occurred between 5 and 6 times a day. There was a significant increase in infant screen time from 2 to 4 months, from 4–7 months, and from 7–11 months, and in technoference from 2 to 4 months and from 4–7 months. Maternal age and household income were not associated with infant screen time, but maternal educational level was negatively associated with infant screen time throughout the first year. No associations were found between technoference and maternal age, maternal educational level, or household income.Future research focusing on infant screen time and technoference should aim at including samples that reflect the general population, include measures of screen time and technoference that do not rely on parental report, and include measures of the effects of early infant screen time and technoference on later development.  相似文献   

19.
20.
The terrorist attacks of September 11, 2001, were traumatic for people living throughout the United States. It has been suggested that people living far from the attacks experienced increased stress because of their exposure to the terrorist events via the media, particularly via television. Following a traumatic or stressful event, individuals may have dreams that reflect that experience. As part of a course on dreaming, individuals recorded their dreams both prior to and following the terrorist attacks of September 11, 2001. On September 12, these same individuals reported their activities and media exposure the previous day. Results revealed (a) changes in dream features following the attacks and (b) a strong relation between exposure to the events on television and changes in dream features after the attacks. Because of the study's within-subjects design, the results provide evidence for a direct association between television viewing and subsequent increases in stress and trauma.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号