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关键词： 甜菜碱   生化性能   测定  

关键词： 合同法   书面形式   合同形式   联合国国际货物销售合同公约   保留   双方当事人   国际货物买卖合同   条约法公约   国际条约   效力  

摘要： 《中华人民共和国合同法》(以下简称《合同法》)已于1999年10月1日起施行。但《合同法》的实施并不能影响有关的国际条约的效力,如《联合国国际货物销售合同公约》(以下简称《公约》),在《合同法》生效以后,它作为规制国际货物买卖这一特别领域的法律依然有效。而我国在1986年12月核准《公约》时,根据《公约》第96条的规定,对《公约》作出了关于书面形式的保留。那么,在10月1日《合同法》开始实施之际,这种保留的效力又将如何呢?两者关于合同形式的不同规定会不会发生冲突?本文拟对此问题作一探讨。一、对《公约》

关键词： 书面合同形式   书面形式   当事人   《合同法》   合同成立   合同关系   行政法规   合同书   订立合同   中外合作勘探开发自然资源合同  

关键词： Parkinson's disease   apoptosis   confocal microscopy   end-labeling   chromatin condensation   DNA fragmentation  

摘要： There is considerable controversy regarding the possibility that nigral dopaminergic neurons may die via apoptosis in Parkinson's disease. It is now clear that both single- and/or double-stranded DNA breaks can be generated in the apoptotic degradative process. Since these breaks may also be present in necrotic cell death, in situ end labeling cannot be used in isolation to identify apoptotic neurons. We have developed a fluorescent double-labeling method that combines in situ end labeling with the simultaneous visualization of chromatin condensation. When viewed with laser confocal scanning microscopy, the structural detail of the nucleus is provided to unequivocally identify apoptotic nuclei. (C) 1999 Elsevier Science Ltd. All rights reserved.

关键词： Bias Epidemiology   Case-Control Studies   Cocarcinogenesis   EnvironmentalExposure  

摘要： In studies of gene-environment interactions, exposure misclassification can lead to bias in the estimation of an interaction effect and increased sample size. The magnitude of the bias and the consequent increase in sample size for fixed misclassification probabilities are highly dependent on the prevalence of the misclassified factor and on the interaction model. This paper describes a relatively simple approach to assess the impact of misclassification on bias in the estimation of multiplicative or additive interactions and on sample size requirements. Applications of this method illustrate that even small errors in the assessment of environmental or genetic factors can result in biased interaction parameters and substantially increased sample size requirements that can compromise the feasibility of the study. Also, an example is provided where nondifferential misclassification biases an additive interaction parameter away from the null value, even under conditions where a multiplicative interaction parameter will always be biased toward the null value. Efforts to improve the accuracy in measuring both genetic and environmental factors are critical for the valid assessment of gene-environment interactions in case-control studies.

关键词： mental states   mother-infant interaction   Mother-Baby Unit   postpartum   schizophrenia  

摘要： Objective: The aim of this study is to examine the role that disturbance of mental state of hospitalised mothers with a postpartum schizophrenic illness plays in determining the quality of mother-infant interactions. Method: We examined the relationship between the nature and severity of symptomatology in mothers with schizophrenia and the quality of her interactions with her infant in a sample of 15 mother-infant dyads admitted to a psychiatric Mother-Baby Unit, Data were obtained at admission and discharge. Results: Mothers with florid positive symptoms and prominent negative symptoms of schizophrenia and their infants were identified as being at particular risk of dis;playing disturbed interactions. The adverse contribution of negative symptoms was often not: evident until after the positive symptoms had resolved. Conclusions: Given that negative symptoms are often treatment resistant, optimal care of mothers with schizophrenia and their infants needs to involve ongoing therapeutic intervention which specifically addresses disturbances of mother-infant interaction. Further research is required to identify which interventions are likely to be of greatest benefit.

关键词： computer-aided diagnosis   classifier design   linear classifier   quadratic classifier   neural network   sample size   feature space dimensionality   ROC analysis  

摘要： Classifier design is one of the key steps in the development of computer-aided diagnosis (CAD) algorithms. A classifier is designed with case samples drawn from the patient population. Generally, the sample size available for classifier design is limited, which introduces variance and bias into the performance of the trained classifier, relative to that obtained with an infinite sample size. For CAD applications, a commonly used performance index for a classifier is the area, A(z), under the receiver operating characteristic (ROC) curve. We have conducted a computer simulation study to investigate the dependence of the mean performance, in terms of A(z), on design sample size for a linear discriminant and two nonlinear classifiers, the quadratic discriminant and the backpropagation neural network (ANN). The performances of the classifiers were compared for four types of class distributions that have specific properties: multivariate normal distributions with equal covariance matrices and unequal means, unequal covariance matrices and unequal means, and unequal covariance matrices and equal means, and a feature space where the two classes were uniformly distributed in disjoint checkerboard regions. We evaluated the performances of the classifiers in feature spaces of dimensionality ranging from 3 to 15, and design sample sizes from 20 to 800 per class. The dependence of the resubstitution and hold-out performance on design (training) sample size (N-t) was investigated. For multivariate normal class distributions with equal covariance matrices, the linear discriminant is the optimal classifier. It was found that its A(z)-versus-1/N-t curves can be closely approximated by linear dependences over the range of sample sizes studied. In the feature spaces with unequal covariance matrices where the quadratic discriminant is optimal, the linear discriminant is inferior to the quadratic discriminant or the ANN when the design sample size is large. However, when the design sam

关键词： space-time interaction   homicide   city-level data   crack markets   guns   youth  

摘要： This paper examines the linkage between crack market activity and gun homicide suggested by Blumstein (1995), who argues that the arrival of crack stimulated an increased availability of guns among juveniles. This greater availability of guns, the argument continues, is responsible for the sharp upswing in juvenile homicide experienced in the United States in the mid-1980s. Using city-level data on crack arrests and gun-related juvenile homicide, we fit a change-point version of the Bass (1969) model of innovation diffusion. We find that, in most large American cities, the diffusion process for crack cocaine experienced an onset of dramatic growth that was followed by a similar, slightly slower growth in gun homicides committed by juveniles. We further use cluster analysis to find that the spatial patterning of the two processes is similar, starting on the East and West Coasts and working their way toward other regions of the nation. Gun use in homicide among slightly older offenders (ages 18-24) also experienced a change at roughly the same time as the juveniles, but the rate;of diffusion was considerably milder than for the younger group;offenders ages 25 or older generally show no growth in gun-related homicide whatsoever. In addition, there is no detectable surge in juvenile nongun homicide activity. Based on these findings, we conclude that the crack cocaine markers-gun availability linkage is highly plausible, and we suggest directions for future research in clarifying the dynamics of the late-1980s surge in juvenile homicide.

关键词： 监督检验   产品质量   企业   质量监督  

关键词： 口头合同形式   书面形式   《合同法》   当事人   交易主体   意思自治   口头形式   订立合同   法律意识   合同自由