中国人口性别结构的区域差异及演变动态分析

人口性别构成是影响人类婚姻、人口再生产的基本因素，也影响国家经济、政治、文化、教育等方面的发展，也是编制经济、文化、教育、科技、卫生、人民生活、劳动、城乡建设等发展规划的重要依据。同时对于中国当前正在进行的和谐社会建设也具有重要意义。利用中国五次人口普查资料及2005年1％人口抽样资料分析了中国总人口性别比演变动态及地理分布特征。表明：（1）中国在历史上是一个性别比偏高的国家，新中国总人口性别比呈下降趋势；（2）1953到2005年，年龄性别比曲线越来越平稳，性别比最高峰值呈现有低龄组向中龄组及高龄组转移的趋势；（3）各省区之间及城乡之间的性别结构差异由大变小；（4）山区性别比高于平原。重工业城市高于其他城市。大城市高于小城市。     

我国农村人口出生性别比偏高的动力机制研究

B超的滥用、强烈的男孩偏好以及对非法流产行为监控的失效共同构成我国出生性别比偏高的充要条件,三者中任一条件不满足都不可能出现出生性别比偏高。尽管B超发明和滥用前出生性别比并没有异常,但也不能说出生性别比偏高与受教育水平、传统文化等因素无关。事实上,这些因素通过影响男孩偏好和B超的可获得性而影响出生性别比。由此出发,促进出生性别比回复正常,短期内应标本兼治,以治标为主———坚决禁止B超的滥用,关键是加强立法和管理;长期内则必须治本———消除男孩偏好,关键是加速农村城市化。     

高Si/C高强度铸铁中C、Si、Si/C的作用及其选择

本文叙述了高Si/C高强度灰铸铁中碳、硅元素存在的形式及其对结晶过程的影响。试验表明,当碳当量一定时,随着Si/C的升高,初生奥氏体枝晶数量增多并且细化和强化,从而构成了强度的基础。该铸铁的强度模式应为“初生奥氏+共晶团”。本文对E型石墨存在的必然性和合理性也进行了讨论。     

A class of weighted dependence measures for bivariate failure time data

This paper considers a class of summary measures of the dependence between a pair of failure time variables over a finite follow-up region. The class consists of measures that are weighted averages of local dependence measures, and includes the cross-ratio-measure and finite region version of Kendall's τ; recently proposed by the authors. Two new special cases are identified that can avoid the need to estimate the bivariate survivor function and that admit explicit variance estimators. Nonparametric estimators of such dependence measures are proposed and are shown to be consistent and asymptotically normal with variances that can be consistently estimated. Properties of selected estimators are evaluated in a simulation study, and the method is illustrated through an analysis of Australian Twin Study data.     

中德婚姻市场供需情况的比较研究

本文从概念、形成机制、度量方法、后果及其解决途径等方面探讨了婚姻挤压问题 ,考虑到婚姻挤压对婚姻寿命、初婚人数及其性别差异的影响而创立了婚姻寿命指数与初婚挤压指数两指标 ,提出了婚姻市场类型的划分标准。通过对中德两国婚姻市场的历史与现状的考察 ,揭示了中德两国婚姻挤压产生的原因、类型、差异和未来的变化趋势 ,并对如何化解中国未来婚姻市场的供求矛盾提出了对策与建议     

Hybridization and speciation in the carabid beetles of the subgenusOhomopterus (Coleoptera, Carabidae, genusCarabus)

Natural hybridization among wingless carabid beetles of the subgenusOhomopterus (Carabidae, genusCarabus) is reviewed, and its significance in the evolution of this subgenus discussed. Natural hybridization occurs between parapatric species of similar size. Two case studies of natural hybridization suggest that natural hybridization could have affected the evolution of this subgenus in different ways. When there is a large difference in genital morphology between hybridizing species, interspecific copulation often results in genital injuries that causes mortality of copulating individuals, and hence reduces the fitness of hybridizing individuals greatly. In such a case, hybridization may be effective in maintaining the parapatric distribution of the two species, and in the long term, may promote reinforcement selection for traits which are effective in prezygotic reproductive isolation. When the morphological difference in genitalia is not so large as to cause genital injury, a hybrid population may be established at the intermediate zone between two parental species, provided that the immigration rates of the two species into the intermediate zone are small. Thus, natural hybridization may have contributed to both divergence and reticulate evolution in this subgenus.     

A multivariate zero-inflated binomial model for the analysis of correlated proportional data

In this paper, a new multivariate zero-inflated binomial (MZIB) distribution is proposed to analyse the correlated proportional data with excessive zeros. The distributional properties of purposed model are studied. The Fisher scoring algorithm and EM algorithm are given for the computation of estimates of parameters in the proposed MZIB model with/without covariates. The score tests and the likelihood ratio tests are derived for assessing both the zero-inflation and the equality of multiple binomial probabilities in correlated proportional data. A limited simulation study is performed to evaluate the performance of derived EM algorithms for the estimation of parameters in the model with/without covariates and to compare the nominal levels and powers of both score tests and likelihood ratio tests. The whitefly data is used to illustrate the proposed methodologies.     

碳限额与交易约束下的企业制造/再制造生产决策

目的/意义随着再制造经济效益和环境效益凸显,越来越多的企业进入再制造领域,与原制造商进行竞争或合作。考虑到碳排放约束,企业面临的生产决策更加复杂。设计/方法基于消费者对新产品和再制造产品的异质需求,构建了制造商和再制造商之间的竞争与合作博弈模型,探讨碳税对制造/再制造决策的影响;结合数值仿真,分析了竞争与合作模式下碳税对企业利润及碳排放的影响。结论/发现不同模式下,企业可根据再制造产品碳排放强度选择不同的生产策略;碳税总是会抑制新产品的生产,当再制造产品碳排放强度低于一定数值时,碳税会促进再制造产品的生产;再制造商竞争会挤兑新产品,使制造商利润减少,再制造门槛提高;当碳税不超过一定限度时,合作模式能够实现经济效益和环境效益双赢。     

格式条款规制标准研究

目的/意义 平台经营者掌握着优势的规制权力,且可能对平台内经营者实施排他、歧视和剥削等不合理限制交易的行为,直接损害平台内经营者的合法权益,阻碍平台市场的自由和公平竞争,迫切需要法律规制。 设计/方法 通过对《电子商务法》实施前的法律规制体系梳理,可知平台经营者不合理限制交易的格式条款规制和竞争法规制兼存在漏洞。一方面,提示说明义务弱化、公平原则适用困难、平台规则备案审查作用有限,使格式条款规制体系无力应对;另一方面,不合理限制交易行为难以被《反垄断法》和《反不正当竞争法》规制体系完全覆盖。 结论/发现 《电子商务法》第35条通过设置不合理限制交易的“禁止+合理抗辩”条款,专门规定行政法律责任,是对平台经营者不合理限制交易法律规制的发展。《电子商务法》第35条所蕴含的“相对优势地位”“不合理限制”“明显不合理限制”等关键实施要点,有待进一步丰富、充实。     

中国都市密集区市际关系中存在的问题及其应对

当前，中国都市密集区市际关系中存在的问题包括产业结构趋同、恶性竞争、城市定位重复混乱、地方保护主义以及基础设施重复建设等。都市密集区市际关系中存在的复杂问题，与市际关系协调机制不成熟、不完善密切相关。创新都市密集区市际关系协调的制度和机制，实现协调主体的多元化、方式多样化、目标长期化，是当前都市密集区发展中殊为迫切的任务。