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1.
动态全参数自调整BP神经网络预测模型的建立   总被引:8,自引:0,他引:8  
李晓峰 《预测》2001,20(3):69-71
本文从减少干预的思想出发,提出了BP神经网络动态全参数自调整学习算法,使得隐层节点和学习速率的选取全部动态实现,实现了学习速率和网络的适应能力,最后又将改善后的BP神经网络应用到经济领域中,得到了比常规经济学模型更优的效果。  相似文献   
2.

Objectives

There is much evidence showing that childhood adversities have considerable effects on the mental and physical health of adults. It could be assumed therefore, that the disease burden of childhood adversities is high. It has not yet been examined, however, whether this is true.

Method

We used data of a large representative sample (N = 7,076) of the general population in the Netherlands. We calculated the disability weight (DW) for each respondent. The DW is a weight factor that reflects the severity of a disease or condition on a scale from 0 (perfect health) to 1 (equivalent to death). We used an algorithm based on the SF-6D to estimate DW. Because the DW indicates the proportion of a healthy life year that is reduced by the specific health state of the individual, it also possible to calculate the total number of years lost due to disability (YLD) in the population. We calculated the years lived with disability (YLD) for 9 different childhood adversities (in the areas of parental psychopathology; abuse and neglect; major life events), as well as for major categories of mental disorders and general medical disorders.

Results

All 9 adversities resulted in a significantly increased DW, except death of a parent before the age of 16. Adversities in the category of abuse and neglect are associated with the highest DWs (0.057), followed by parental psychopathology (0.031) and life events during childhood (0.012). All adversities (46.4% of the population reports one or more adversity) are associated with 20.7 YLD/1,000, which is more than all mental disorders together (12.9 YLD/1,000). The category of abuse/neglect has the highest YLD/1,000 (15.8), which is also higher than all mental disorders together. Adjustment for the presence of mental and general medical disorders resulted in comparable outcomes.

Conclusions

Childhood adversities are more important from a public health point of view than all common mental disorders together, and should be a priority for public health interventions.  相似文献   
3.
职业教育发展模式关系到职业教育体系的正常运行,从职业教育的区域结构优化的角度来看,区域职业教育的发展应因地制宜,走非均衡发展的道路。  相似文献   
4.
简要概括纳税筹划的含义、特点和原则,同时以房地产企业为真实背景,以实际筹划案例为现实基础,详细分析房地产企业的主要相关税种应当如何进行正确的纳税筹划,并指出纳税筹划是企业合理降低成本、提高竞争力的重要途径之一。  相似文献   
5.
国际体育法若干基本问题研究   总被引:2,自引:1,他引:1  
国际体育法是人类社会发展到一定阶段的产物,是一门新兴的法学分支,其调整对象就是含有国际或者跨国或者涉外因素的体育关系;其渊源应该包括国际条约、国际习惯或者国际惯例、体育组织规范、国内法以及一般法律原则;其主体包括政府间国际组织、运动员、国际和国内体育组织、国家政府和其他从事体育运动的自然人和法人;它是一个包括国际法和国内法在内的特殊法律部门。  相似文献   
6.
张凯  陆海曙  陆玉梅 《资源科学》2021,43(9):1778-1793
中国结构性缺水和资源型缺水“双缺”现象共存,亟需有效提高水资源利用效率。本文选取“资源禀赋-社会经济-生态环境”三重属性约束下的水资源承载力作为投入变量,构建无需强制性调整环境因素和统计噪音影响的RAM-SFA-RAM组合效率测度模型,基于中国31个省份2003—2017年面板数据进行实证研究。结果表明:①选取三重属性约束下的水资源承载力测度水资源利用效率更贴合研究区域的实际情况,中国水资源承载力在研究期内具有稳步增长态势,呈现东低西高、北低南高分布格局;②环境规制因素对投入变量过剩松弛和产出变量不足松弛具有不同程度的影响,R&D经费支出对劳动力投入过剩的松弛始终为负向影响,人口密度对投入和产出变量松弛的影响呈现窄幅正负波动,植被覆盖率对投入和产出变量松弛均为正向影响;③在剔除统计噪音和环境规制影响后,中国南方大部分省份的水资源利用效率值有所提升,北方大部分省份有所降低,表明统计噪音和环境规制因素对不同省份的影响具有差异性。因此,在制定政策时应当因地制宜、因省施策,同时需完善水资源管理监管制度,积极构建水权交易市场促使水资源市场化配置“流动”。  相似文献   
7.
通过对水泵和水箱联和供水系统中水箱运行状况的分析,提出水箱有效容积应分为水箱调节水量和储备水量两个部分。对储备水量的极限值进行分析,给出了水箱有效容积的计算公式。  相似文献   
8.
Mean and mean-and-variance corrections are the 2 major principles to develop test statistics with violation of conditions. In structural equation modeling (SEM), mean-rescaled and mean-and-variance-adjusted test statistics have been recommended under different contexts. However, recent studies indicated that their Type I error rates vary from 0% to 100% as the number of variables p increases. Can we still trust the 2 principles and what alternative rules can be used to develop test statistics for SEM with “big data”? This article addresses the issues by a large-scale Monte Carlo study. Results indicate that empirical means and standard deviations of each statistic can differ from their expected values many times in standardized units when p is large. Thus, the problems in Type I error control with the 2 statistics are because they do not possess the properties to which they are entitled, not because of the wrongdoing of the mean and mean-and-variance corrections. However, the 2 principles need to be implemented using small sample methodology instead of asymptotics. Results also indicate that distributions other than chi-square might better describe the behavior of test statistics in SEM with big data.  相似文献   
9.
本文根据JUKID DL8700系列高速单针平缝缝纫机使用中经常出现的故障现象,简要介绍了故障的排除方法和相关调整要领。  相似文献   
10.
Evaluative bibliometrics is concerned with comparing research units by using statistical procedures. According to Williams (2012) an empirical study should be concerned with the substantive and practical significance of the findings as well as the sign and statistical significance of effects. In this study we will explain what adjusted predictions and marginal effects are and how useful they are for institutional evaluative bibliometrics. As an illustration, we will calculate a regression model using publications (and citation data) produced by four universities in German-speaking countries from 1980 to 2010. We will show how these predictions and effects can be estimated and plotted, and how this makes it far easier to get a practical feel for the substantive meaning of results in evaluative bibliometric studies. An added benefit of this approach is that it makes it far easier to explain results obtained via sophisticated statistical techniques to a broader and sometimes non-technical audience. We will focus particularly on Average Adjusted Predictions (AAPs), Average Marginal Effects (AMEs), Adjusted Predictions at Representative Values (APRVs) and Marginal Effects at Representative Values (MERVs).  相似文献   
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