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21.
生态安全是国家安全体系的组成部分,也是人类维持生命和从事各种活动的物质基础。本文全面论述建设国家生态安全体系具有重要战略意义,并提出建设国家生态安全体系的法律架构思考的六项建议。  相似文献   
22.
The last observation carried forward (LOCF) approach is commonly utilized to handle missing values in the primary analysis of clinical trials. However, recent evidence suggests that likelihood‐based analyses developed under the missing at random (MAR) framework are sensible alternatives. The objective of this study was to assess the Type I error rates from a likelihood‐based MAR approach – mixed‐model repeated measures (MMRM) – compared with LOCF when estimating treatment contrasts for mean change from baseline to endpoint (Δ). Data emulating neuropsychiatric clinical trials were simulated in a 4 × 4 factorial arrangement of scenarios, using four patterns of mean changes over time and four strategies for deleting data to generate subject dropout via an MAR mechanism. In data with no dropout, estimates of Δ and SEΔ from MMRM and LOCF were identical. In data with dropout, the Type I error rates (averaged across all scenarios) for MMRM and LOCF were 5.49% and 16.76%, respectively. In 11 of the 16 scenarios, the Type I error rate from MMRM was at least 1.00% closer to the expected rate of 5.00% than the corresponding rate from LOCF. In no scenario did LOCF yield a Type I error rate that was at least 1.00% closer to the expected rate than the corresponding rate from MMRM. The average estimate of SEΔ from MMRM was greater in data with dropout than in complete data, whereas the average estimate of SEΔ from LOCF was smaller in data with dropout than in complete data, suggesting that standard errors from MMRM better reflected the uncertainty in the data. The results from this investigation support those from previous studies, which found that MMRM provided reasonable control of Type I error even in the presence of MNAR missingness. No universally best approach to analysis of longitudinal data exists. However, likelihood‐based MAR approaches have been shown to perform well in a variety of situations and are a sensible alternative to the LOCF approach. MNAR methods can be used within a sensitivity analysis framework to test the potential presence and impact of MNAR data, thereby assessing robustness of results from an MAR method. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   
23.
四川地区农民持续增收的制约因素分析   总被引:1,自引:0,他引:1  
根据四川省统计局的历年数据,本文分析了四川省农民收入增长的规律:改革来,四川农民收入总量上呈现逐年增长、增幅减缓的特征;四川农民收入水平在全国的排位下降。宏观经济分析表明,影响农民收入持续增长的主要有外部因素如制度障碍、农业投入不足、农资价格上涨等,内部因素如生产结构不合理、基础设施脆弱和农民素质不高等方面。因此,要构建农民增收的长效机制必须突破制度障碍。  相似文献   
24.
K. Goda  H. P. Hong 《Risk analysis》2008,28(2):523-537
Seismic risk can be reduced by implementing newly developed seismic provisions in design codes. Furthermore, financial protection or enhanced utility and happiness for stakeholders could be gained through the purchase of earthquake insurance. If this is not so, there would be no market for such insurance. However, perceived benefit associated with insurance is not universally shared by stakeholders partly due to their diverse risk attitudes. This study investigates the implied seismic design preference with insurance options for decisionmakers of bounded rationality whose preferences could be adequately represented by the cumulative prospect theory (CPT). The investigation is focused on assessing the sensitivity of the implied seismic design preference with insurance options to model parameters of the CPT and to fair and unfair insurance arrangements. Numerical results suggest that human cognitive limitation and risk perception can affect the implied seismic design preference by the CPT significantly. The mandatory purchase of fair insurance will lead the implied seismic design preference to the optimum design level that is dictated by the minimum expected lifecycle cost rule. Unfair insurance decreases the expected gain as well as its associated variability, which is preferred by risk-averse decisionmakers. The obtained results of the implied preference for the combination of the seismic design level and insurance option suggest that property owners, financial institutions, and municipalities can take advantage of affordable insurance to establish successful seismic risk management strategies.  相似文献   
25.
Summary.  Non-ignorable missing data, a serious problem in both clinical trials and observational studies, can lead to biased inferences. Quality-of-life measures have become increasingly popular in clinical trials. However, these measures are often incompletely observed, and investigators may suspect that missing quality-of-life data are likely to be non-ignorable. Although several recent references have addressed missing covariates in survival analysis, they all required the assumption that missingness is at random or that all covariates are discrete. We present a method for estimating the parameters in the Cox proportional hazards model when missing covariates may be non-ignorable and continuous or discrete. Our method is useful in reducing the bias and improving efficiency in the presence of missing data. The methodology clearly specifies assumptions about the missing data mechanism and, through sensitivity analysis, helps investigators to understand the potential effect of missing data on study results.  相似文献   
26.
Time, Self, and the Curiously Abstract Concept of Agency*   总被引:2,自引:0,他引:2  
The term "agency" is quite slippery and is used differently depending on the epistemological roots and goals of scholars who employ it. Distressingly, the sociological literature on the concept rarely addresses relevant social psychological research. We take a social behaviorist approach to agency by suggesting that individual temporal orientations are underutilized in conceptualizing this core sociological concept. Different temporal foci—the actor's engaged response to situational circumstances—implicate different forms of agency. This article offers a theoretical model involving four analytical types of agency ("existential,""identity,""pragmatic," and "life course") that are often conflated across treatments of the topic. Each mode of agency overlaps with established social psychological literatures, most notably about the self, enabling scholars to anchor overly abstract treatments of agency within established research literatures.  相似文献   
27.
This article provides a critical review of literature on the relationship between gender and the 'new paradigm' of health. An overview of the feminist critique of health is given, from the Women's Health Movement of the late 1960s and early feminist debates about medicalisation, to more recent discussions about structural inequalities between men and women, eating disorders, and AIDS. I then go on to explore the feminist response to the so-called 'new paradigm' of health (an approach that emphasises health promotion, individual responsibility for health, and body-monitoring). Arguments that health promotion initiatives target women and confirm their position as principal guardians of health within the family are considered, as well as literature on the breast cancer awareness campaign. I then explore the growing body of literature on masculinity and health, and its account of the relationship between gender and current ideas about healthiness. Finally, I offer up some suggestions for the direction a new feminist critique of health might take.  相似文献   
28.
俄罗斯是一个有着深刻宗教情结的民族.东正教作为文化现象和意识形态,深深根植于俄罗斯民众的意识里,浓浓地融入俄罗斯民族的精神中,深刻地影响着俄国的历史与现实.为实现国家统一并加强皇权,以君权神授为宗旨的基督教作为最有力的思想武器被罗斯统治者"请入"罗斯.至此,无论是在鞑靼蒙古人入侵时期,还是在第一、二次卫国战争等俄苏历史的紧要关头,俄罗斯东正教均发挥了其社会整合与道德教化作用,并在促进国家统一、弘扬爱国主义传统、凝聚民族精神、规范民众道德和维护社会稳定等方面做出了积极而重要的历史贡献.  相似文献   
29.
总体上看,全国各地高校在双语教学模式试点及具体实践中取得了显著的成绩,双语教学模式推广前景良好。但是,应该看到在推进双语教学模式的实践过程中,也出现了一些需要我们认真分析和思考的问题,本文首先针对我国高校双语教学模式的现状及发展特征展开分析,进而提出了相应的对策思考。  相似文献   
30.
先进制造业基本特征刍议   总被引:1,自引:0,他引:1  
本文结合当今先进制造业已具备的几个基本特征分析了我国制造业发展中存在的一些问题 ,并对如何解决这些问题提出了自己的观点与见解  相似文献   
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