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1.
Nanoparticles of trivalent Eu3+-doped Nd2O3 phosphors have been prepared using a low-temperature solution combustion method with metal nitrate as precursor and oxalyldihydrazide as a fuel at a fairly low temperature (<500°C) and in a very short time (<5 min). A powder X-ray diffraction pattern reveals that cubic Nd2O3 : Eu3+ crystallites are directly obtained without the requirement of further calcinations. The crystallite size, evaluated from Scherer's formula, was found to be in the range of 20–30 nm. The microstructure and morphology were studied by scanning electron microscopy, which showed the phosphor to be foamy and fluffy in nature. Thermoluminescence characteristics of the Nd2O3 : Eu3+ have been studied using gamma irradiation. These demonstrate that the phosphor is suitable for use as a dosimeter.  相似文献   

2.
3.
An analysis of cross-sections perpendicular to the main diagonal of a cubic elementary cell of a Samson structure–β-Mg2Al3 has been conducted. It has been proved that all skeleton atoms, i.e. which occupy their positions with probability of 100%, form a framework of hexagonal planes. These planes are a part of three domains shifted with respect to each other by one-third of the length of cube's diagonal. Space between domains is filled up by clusters with partially occupied atomic positions. For hexagonal domains, the elementary cell and positions of decorating atoms have been determined.  相似文献   

4.
This article reports the construction of a typology of behavior problem patterns, as scored on the Child Behavior Profile. Hierarchical cluster analysis was used to identify reliable profile patterns that characterize clinically referred boys and girls aged 6–11 and 12–16. Procedures for classifying the profiles of individual children were developed and good agreement was obtained between classifications based on ratings by mothers and a clinician. The distribution of profile patterns was determined for each age and sex group. Children classified by different patterns were found to differ significantly in age, race, school performance, and amount and quality of participation in activities and social relationships. Issues in the application of cluster analysis to behavioral data were analyzed and various options for the classification of individual cases were compared.  相似文献   

5.
This article describes two experiments linking native-language grammar rules with implications for perception of similarity and recognition memory. In prenominal languages (e.g., English), adjectives usually precede nouns, whereas in postnominal languages (e.g., Portuguese), nouns usually precede adjectives. We explored the influence of such rules upon similarity judgments about, and recognition of, objects with multiple category attributes (one nominal attribute and one adjectival attribute). The results supported the hypothesized primacy effect of native-language word order such that nouns generally carried more weight for Portuguese speakers than for English speakers. This pattern was observed for judgments of similarity (i.e., Portuguese speakers tended to judge objects that shared a noun-designated attribute as more similar than did English speakers), as well as for false alarms in recognition memory (i.e., Portuguese speakers tended to falsely recognize more objects if they possessed a familiar noun attribute, relative to English speakers). The implications of such linguistic effects for the cognition of similarity and memory are discussed.  相似文献   

6.
Objective: The present study aimed to investigate the factor structure and psychometric properties of the Cohen–Hoberman inventory of physical symptoms (CHIPS). Construct and discriminant validity were examined by assessing associations between factors and subjective health complaints (SHC) inventory subscales in addition to measures of pain sensitivity, perceived stress and psychological distress.

Design: A cross-sectional online survey was conducted with 535 healthy individuals from the general population (80.6% female, mean age = 29.80).

Main outcome measures: Participants completed CHIPS, SHC, perceived stress scale, pain sensitivity questionnaire, and hospital anxiety and depression scale.

Results: Principal components analysis demonstrated that CHIPS comprised 8 ‘symptoms’ factors as follows; ‘sympathetic/cardiac’ (7 items; α = .827), ‘muscular’ (6 items; α = .752), ‘metabolic’ (5 items; α = .736), ‘gastrointestinal’ (5 items; α = .714), ‘vasovagal’ (4 items; α = .743), ‘cold/flu’ (2 items; α = .837), ‘headache’ (2 items; α = .690) and ‘minor haemorrhagic’ (2 items; α = .309). Significant correlations were observed between factors and SHC subscales (moderate-high), pain sensitivity (negligible-low) and levels of perceived stress and anxiety (low-moderate) indicating good construct, and discriminant validity, respectively.

Conclusions: CHIPS is a multidimensional and internally consistent measurement of physical symptoms. The postulated factor structure may be used for research purposes particularly in health psychology, to consistently differentiate between clusters of self-reported symptoms.  相似文献   


7.
Previous research has shown that good readers are superior to poor readers in their use of orthographic structure. The purpose of the present study was to assess the role of experience in determining these differences. Results showed that poor sixth-grade readers used orthographic structure to speed their matching judgments just as effectively as good sixth-grade readers. The apparent discrepancy in results between the present study and previous work is explained in terms of the “partial-information hypothesis” which states that the performance of good readers is superior to that of poor readers in situations which depend on the use of partial information. Support for this view was provided by the fact that good readers recognized significantly more items on a recognition test than did the poor readers.  相似文献   

8.
The Big Five Inventory–2 (BFI-2) uses 60 items to hierarchically assess the Big Five personality domains and 15 more-specific facet traits. The present research develops two abbreviated forms of the BFI-2—the 30-item BFI-2-S and the 15-item BFI-2-XS—and then examines their measurement properties. At the level of the Big Five domains, we find that the BFI-2-S and BFI-2-XS retain much of the full measure’s reliability and validity. At the facet level, we find that the BFI-2-S may be useful for examining facet traits in reasonably large samples, whereas the BFI-2-XS should not be used to assess facets. Finally, we discuss some key tradeoffs to consider when deciding whether to administer an abbreviated form instead of the full BFI-2.  相似文献   

9.
The ability to quickly detect and respond to visual stimuli in the environment is critical to many human activities. While such perceptual and visual–motor skills are important in a myriad of contexts, considerable variability exists between individuals in these abilities. To better understand the sources of this variability, we assessed perceptual and visual–motor skills in a large sample of 230 healthy individuals via the Nike SPARQ Sensory Station, and compared variability in their behavioral performance to demographic, state, sleep and consumption characteristics. Dimension reduction and regression analyses indicated three underlying factors: Visual–Motor Control, Visual Sensitivity, and Eye Quickness, which accounted for roughly half of the overall population variance in performance on this battery. Inter-individual variability in Visual–Motor Control was correlated with gender and circadian patters such that performance on this factor was better for males and for those who had been awake for a longer period of time before assessment. The current findings indicate that abilities involving coordinated hand movements in response to stimuli are subject to greater individual variability, while visual sensitivity and occulomotor control are largely stable across individuals.  相似文献   

10.
Abstract

It is shown that in the high-Tc YBa2 Cu3 O~7 superconductor the critical temperature is a function of the orthorhombic distortion (b–a)/a of the unit cell. From the extrapolation of the (b - a)/a ratio against Tc , a maximum critical temperature of 66 K for the tetragonal phase of YBa2 Cu3 O~7 was predicted. From the correlation between the transition width δTc and the orthorhombic distortion there was deduced an upper limit for Tc , in the orthorhombic phase of YBa2 Cu3 O~7 of 94·5K.  相似文献   

11.
It has been shown that acquired stimulus–response bindings result from at least two types of associations from the stimulus to the task (stimulus–task or stimulus–classification; S–C) and from the stimulus to the motor response (stimulus–response or stimulus–action; S–A). These types of associations have been shown to independently affect behaviour. This finding suggests that they are processed in different pathways or different parts of a pathway at the neural level. Here we test a hypothesis that such associations may be differentially affected by repetition learning and that such effects may be detected by measuring their durability against overwriting. We show that both S–C and S–A associations are in fact strengthened when learning is boosted by increasing repetitions of the primes. However, the results further suggest that associations between stimuli and actions have less durable effects on behaviour and that the durability of S–C and S–A associations is independent of repetition learning. This is an important finding for the understanding of the underlying mechanisms of associative learning and particularly raises the question of which processes may affect flexibility of learning.  相似文献   

12.
Affect, accessibility of material in memory, and behavior: a cognitive loop?   总被引:10,自引:0,他引:10  
Two studies investigated the effect of good mood on cognitive processes. In the first study, conducted in a shopping mall, a positive feeling state was induced by giving subjects a free gift, and good mood, thus induced, was found to improve subjects' evaluations of the performance and service records of products they owned. In the second study, in which affect was induced by having subjects win or lose a computer game in a laboratory setting, subjects who had won the game were found to be better able to recall positive material in memory. The results of the two studies are discussed in terms of the effect that feelings have on accessibility of cognitions. In addition, the nature of affect and the relationship between good mood and behavior (such as helping) are discussed in terms of this proposed cognitive process.  相似文献   

13.
Arbib MA  Erdi P 《The Behavioral and brain sciences》2000,23(4):513-33; discussion 533-71
NEURAL ORGANIZATION: Structure, function, and dynamics shows how theory and experiment can supplement each other in an integrated, evolving account of the brain's structure, function, and dynamics. (1) STRUCTURE: Studies of brain function and dynamics build on and contribute to an understanding of many brain regions, the neural circuits that constitute them, and their spatial relations. We emphasize Szentágothai's modular architectonics principle, but also stress the importance of the microcomplexes of cerebellar circuitry and the lamellae of hippocampus. (2) FUNCTION: Control of eye movements, reaching and grasping, cognitive maps, and the roles of vision receive a functional decomposition in terms of schemas. Hypotheses as to how each schema is implemented through the interaction of specific brain regions provide the basis for modeling the overall function by neural networks constrained by neural data. Synthetic PET integrates modeling of primate circuitry with data from human brain imaging. (3) DYNAMICS: Dynamic system theory analyzes spatiotemporal neural phenomena, such as oscillatory and chaotic activity in both single neurons and (often synchronized) neural networks, the self-organizing development and plasticity of ordered neural structures, and learning and memory phenomena associated with synaptic modification. Rhythm generation involves multiple levels of analysis, from intrinsic cellular processes to loops involving multiple brain regions. A variety of rhythms are related to memory functions. The Précis presents a multifaceted case study of the hippocampus. We conclude with the claim that language and other cognitive processes can be fruitfully studied within the framework of neural organization that the authors have charted with John Szentágothai.  相似文献   

14.
One of the high-temperature metastable phases found in the MgGa2O4–Ga2O3 system is the εMg non-stoichiometric Mg gallate. It has a one-dimensional periodic antiphase boundary (PAPB) structure based on the spinel structure. The APBs are parallel to the {3?1?0} planes and the APB vectors are of the 1/4?1 1 0? type when referred to the spinel structure. This generally leads to the existence of 12 monoclinic twin variants in the studied samples. By comparing the X-ray or electronic diffraction patterns of both phases, it will be shown that the recently discovered?λ?transition-alumina has the same type of structure.  相似文献   

15.
Brian Epstein’s The Ant Trap is a praiseworthy addition to literature on social ontology and the philosophy of social sciences. Its central aim is to challenge received views about the social world – views with which social scientists and philosophers have aimed to answer questions about the nature of social science and about those things that social sciences aim to model and explain, like social facts, objects and phenomena. The received views that Epstein critiques deal with these issues in an overly people-centered manner. After all, even though social facts and phenomena clearly involve individual people arranged in certain ways, we must still spell out how people are involved in social facts and phenomena. There are many metaphysical questions about social properties, relations, dependence, constitution, causation, and facts that cannot be answered (for instance) just be looking at individual people alone. In order to answer questions about (e.g.) how one social entity depends for its existence on another, we need different metaphysical tools. Epstein thus holds that social ontological explanations would greatly benefit from making use of the theoretical toolkit that contemporary analytical metaphysics has to offer. He focuses specifically on two metaphysical instruments: grounding and anchoring. This paper examines Epstein’s understanding and use of these tools. I contend that Epstein is exactly right to say that contemporary metaphysics contains many theoretical instruments that can be fruitfully applied to social ontological analyses. However, I am unconvinced that Epstein’s tools achieve what they set out to do. In particular, I will address two issues: (1) How is grounding for Epstein meant to work? (2) Is anchoring distinct from grounding, and a relation that we need in social ontology?  相似文献   

16.
Longitudinal linkages between intentional exposure to x-rated material and sexually aggressive behavior were examined among youth 10-15 year olds surveyed nationally in the United States. At Wave 1 in 2006, participants (n = 1,588) were queried about these exposures and outcomes in the preceding 12 months. Wave 2 data (n = 1,206) were collected approximately 12 months after Wave 1 and Wave 3 data (n = 1,159) were collected approximately 24 months after Wave 1. Thus, data for this project represent a 36-month time frame. A marginal model with generalized estimating equations was used to represent the population-average odds of sexually aggressive behavior over the 36 months as a function of exposure to x-rated material over the same time and to account for clustering in the data within person over time. An average of 5% of youth reported perpetrating sexually aggressive behavior and 23% of youth reported intentional exposure to x-rated material. After adjusting for other potentially influential proximal (i.e., sexual aggression victimization) and distal characteristics (e.g., substance use), we found that intentional exposure to violent x-rated material over time predicted an almost 6-fold increase in the odds of self-reported sexually aggressive behavior (aOR: 5.8, 95% CI: 3.2, 10.5), whereas exposure to nonviolent x-rated material was not statistically significantly related (aOR: 1.7, 95% CI: 0.94, 2.9). Associations were similar for boys and girls (boys nonviolent x-rated material aOR = 2.0, 95% CI: 0.8, 4.7; violent x-rated material aOR = 6.5, 95% CI: 2.7, 15.3; girls nonviolent x-rated material aOR = 1.2, 95% CI: 0.5, 3.2; violet x-rated material aOR = 6.1, 95% CI: 2.5, 14.8).  相似文献   

17.
We report on the manifestation and interconnected photoluminescence and electron paramagnetic resonance responses in gadolinium oxide (Gd2O3) nanorods subjected to 80 MeV carbon ion irradiation. On increasing the irradiation fluence between 1 × 1011 and 3 × 1012 ions/cm2, the emission associated with neutral oxygen vacancies (VOx), positioned at ~350 nm, undergoes a steady increase compared to that associated with singly charged vacancies (VO+), located at ~414 nm. The enhancement of spin–spin relaxation time (τss) is ascribed to a substantial changeover from VO+ to VOx defects with irradiation, the former being recognized as the major contributor to paramagnetic centres. Interconnected luminescence and spin–spin relaxation could provide insight for making advanced nanophosphors and spin valve elements.  相似文献   

18.
Forty-three medical students and 78 nursing students each filled out four copies of the Interpersonal Check List. The subjects described self, ideal self as physician or nurse, and typical and ideal work partner. For each questionnaire the two summary scores Dom and Lov were computed. The results indicate a discrepancy between concepts of self and ideal self and the results also point to considerable disagreement between medical students and nursing students about their roles on the physician-nurse team.  相似文献   

19.
Behavioral inhibition (BI) discourages children from interacting, predisposing them to isolation, social anxiety, and depression. We have created the Behavioral Inhibition Scale for Children Aged 3 to 6 (BIS 3–6) to detect this trait early. Parents and teachers of 365 preschoolers completed different versions of the BIS 3–6 and provided measures of psychopathology. Both versions are structured into 1 factor that explains over 40% of total variability and displays excellent internal consistency (α = .95). The moderate correlations with measures of internalizing symptoms (r = .50) and nonexistent correlations with externalizing measures suggest adequate convergent and discriminant validity. A new scoring system is proposed.  相似文献   

20.
Research has shown that decision-making groups with distributed information perform better when group members know which member is knowledgeable about what. Thus far research has been unable to identify the process responsible for this effect. In the present study, we propose that group members’ task representations mediate the effect of knowledge about the distribution of information on decision performance. Building on this proposition, we also propose that reflection about the task moderates the effect of knowledge about distributed information through its effect on task representations. These hypotheses were put to the test in an experimental study of decision-making groups (N = 125). As predicted, knowledge of distributed information interacted with reflection to affect decision quality. Findings confirmed the proposed mediating role of task representations and information elaboration.  相似文献   

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