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71.
人体骨组织有着复杂的结构和生理机制,骨重建理论经历了定性分析、定量计算和计算机定量数值模拟三个阶段。目前,存在力学模型和现象模型两类成熟的骨重建模型,力学模型的共性就是表观密度随一定的力学刺激而变化,现象模型由基本多细胞单元的损伤状态和孔隙度变化来决定。大多数股骨重建仿真模型仍然将骨量的分布看作是各向同性的,这就不能完全反映骨组织微构造的本构关系。本文是对骨重建仿真模型的控制方程进行综述。  相似文献   
72.
多参数信息融合实现非脑电的睡眠结构分期   总被引:7,自引:3,他引:7  
目前临床睡眠分析的主要手段是多导睡眠图(Polysomnograph,PSG),用仪器记录被测者整晚的脑电、眼动电和颏肌电等生理参数,计算机进行自动睡眠分期,再由技术人员依据国际标准进行校正.几十年来PSG保持着睡眠分期金标准的地位.提出在不使用脑电的条件下,利用较易获得的心动周期、呼吸、体动等基本生理参数,提取其中与睡眠过程及其变化有关的规律和信息,建立知识规则库,采用不确定推理的证据理论进行多参数睡眠信息融合计算,实现睡眠结构分期.50余例与PSG对照试验结果表明:醒睡的平均符合率达90%以上,基本睡眠结构的平均符合率达75%以上,证明该技术达到了应用的要求.  相似文献   
73.
The main purpose of the study was to compare the efficiency of the Fishbein and Ajzen and the Triandis models to predict (1) the intention to participate regularly in some physical activities during free time within a 3-week period and (2) the exercise behavior within these 3 weeks among a group of 166 subjects, aged 22 to 65 years. Our results show that the Triandis model was as efficient as the Fishbein and Ajzen model in predicting the exercise behavior. However, the results obtained from the Triandis model demonstrate the importance of the habit of exercising in predicting the exercise behavior. Moreover, the Triandis model was superior to the Fishbein and Ajzen model in explaining behavioral intention. Of particular interest was the salience of the affective, social, and personal belief components of the Triandis model. In addition, from a practical perspective, this comparative study showed that (1) to exercise regularly is perceived as hard work, and (2) individuals believe that it is their own responsibility to exercise or not to exercise.  相似文献   
74.
任务的呈现方式对孤独症儿童误念理解的影响   总被引:6,自引:0,他引:6  
目的:探讨一种更适于测试孤独症儿童误念理解能力的方法.方法:2(呈现方式)×2(被试类型)设计,采用经典误念任务,使用计算机多媒体动画呈现方式与传统图片-实物呈现方式,分别测试20名孤独症儿童和言语能力(PPVT-R)匹配的正常儿童.结果:呈现方式的主效应非常显著(P<0.001),动画呈现方式使正常儿童和孤独症儿童的误念理解成绩都有提高,孤独症儿童的提高更大.结论:孤独症儿童的误念理解能力在误念任务的传统呈现方式之下可能被低估了.充分考虑孤独症认知缺陷的多样性,使用恰当的任务方式,可能会更真实地反映他们的心理理论发展水平.  相似文献   
75.
Almost nothing is concretely known about childless elderly in cross-cultural perspective. Few published papers have appeared on this social category in the West, although childless elders make up (at least) 20% of the population of elderly in many Western nations. Little is known about childless elderly in the Third World. This paper provides some theoretical background to the study of childless elderly and articulates some social policy concerns about them. It suggests that there are five important questions to examine concerning the lives of childless elderly. These include, how childless aged are or are not provided for in societies in which a great deal of the care of the aged is undertaken by children; how kinship functions as a matrix for care; how the increasingly common phenomenon of voluntary childless may give meaning to childlessness in late life; how childlessness fits with such social science models such as the developmental cycle; and, the relationship of this phenomenon to changing opportunities for women. The paper further examines how factors such as fertility, systems of caregiving, the social meaning of childlessness, alternatives to childlessness such as adoption, and educational and economic opportunities may affect the lives of childless elders.  相似文献   
76.
Radiographic quantification of alveolar bone level changes   总被引:3,自引:0,他引:3  
The "random burst" theory has recently been proposed as an explanation of the pattern of periodontal disease progression. The theory predicts that the progression of bone loss at individual sites is not dependent upon previous bone loss and age. A longitudinal radiographic study was designed to test this hypothesis, and to describe the changes in bone level over 2 years in a group of 180 subjects (18-68 years of age) who were not under systematic periodontal treatment. The results indicated that 94% of the sites did not show significant changes in the alveolar bone level during the observation period. The mean annual bone loss for the total population was 0.11 mm. By regressing longitudinal bone loss upon age, it was shown that the rate of bone loss increased rapidly between 33 and 56 years of age while a different pattern was shown for the age intervals 18-32 and 57-68 years. Also, the rate of bone loss increased with increasing initial bone loss. This was less evident in the oldest age group. It was concluded that the progression of bone loss in the present material is consistent with a "burst" theory. However, the progression did not occur randomly with regard to previous loss of alveolar bone and time.  相似文献   
77.
Summary The bounds of the accumulation profile can be predicted on the basis of the mean disposition residence time (MDRT) of a drug. The time to reach 90% of the plateau level (t 0.9) is less than 3.7 MDRT. This prediction can be improved if, in addition, the variance of disposition residence time (VDRT, CV D 2 =VDRT/MDRT2), or the terminal exponential coefficient (), is known. For CV D 2 1 or MDRT1, the time to reach steady state (t0.9) approaches 2.3 MDRT (limiting case of monoexponential drug disposition curve). Conditions are stated under which can be regarded as the principal determinant of the accumulation rate.  相似文献   
78.
基于共生理论,从共生单位、共生环境、共生模式和共生界面4个要素入手,分析国家医联体绩效考核指标中存在问题。国家医联体绩效考核指标的横向可比性有待增强,部分指标标准未统一,指标导向性不强。由此总结出加强医联体绩效考核的导向性作用,强化指标的横向可比性,将医联体文化融合的指标纳入医联体绩效考核四项措施。  相似文献   
79.
目的:恶性肿瘤已成为严重威胁人类健康的公共卫生问题,中草药因“简、便、廉、验”,通过“多成分-多靶点-多通路”发挥抗肿瘤作用成为研究热点。该文总结近年来茯苓主要活性成分三萜类、多糖类等化合物抗肿瘤的研究进展并加以述评,以期为茯苓抗肿瘤提供客观且全面的研究参考。方法:对PubMed、谷歌学术和中国知网(CNKI)等数据库进行文献搜索,搜索时间跨度为1995至2022年,关键词定义为茯苓和恶性肿瘤,文献包括基础研究、临床观察和综述。结果:检索结果显示茯苓主要活性成分以茯苓酸为代表的三萜类、以茯苓多糖为代表的多糖类等化合物在抑制恶性肿瘤增殖与诱导凋亡、抑制侵袭转移、调节患者免疫功能及提高生活质量等方面表现出广泛的药理作用。另外,茯苓的栽培方式、用药部位、生长环境、采收周期、用药剂型、加工方式等均影响茯苓不同有效成分的含量。结论:茯苓多糖及三萜类成分在抗肿瘤方面具有较大的潜力,但仍面临着创新性不足和缺乏高质量临床试验的问题。中药茯苓各方面质控标准化的缺失可能会影响茯苓发挥其最大程度的抗肿瘤作用,亟待个性化、标准化的质控标准出台。茯苓抗肿瘤具备一定的科学性和良好的应用前景,但从基础研究到实际应用...  相似文献   
80.
Self-management of health requires skills to obtain, process, understand, and use health-related information. Assessment of adolescents’ functional health literacy requires valid, reliable, and low-burden tools. The main objective of this study was to adapt and study the psychometric properties of the Newest Vital Sign for the Portuguese adolescents’ population (NVS-PTeen). Classic psychometric indicators of reliability and validity were combined with item response theory (IRT) analyses in a cross-sectional survey, complemented with a 3-month test-retest assessment. The NVS-PTeen was self-administered to students enrolled in grades 8 to 12 (12 to 17 years old) in a school setting. Overall, 386 students (191 girls) from 16 classes of the same school participated in the study (mean age = 14.5; SD = 1.5). Internal reliability of the NVS-PTeen was α = 0.60. The NVS-PTeen total score was positively and significantly correlated with Portuguese (r = 0.28) and mathematics scores (r = 0.31), school years (r = 0.31), and age (r = 0.19). Similar to the original scale (for the U.S.), the NVS-PTeen is composed of two dimensions, reading-related literacy and numeracy. Temporal reliability is adequate, though with a learning effect. IRT analyses revealed differences in difficulty and discriminative capacity among items, all with adequate outfit and infit values. Results showed that the NVS-PTeen is valid and reliable, sensible to inter-individual educational differences, and adequate for regular screening of functional health literacy in adolescents.  相似文献   
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