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61.
The extent of carcinogen regulation under existing U.S. environmental statutes is assessed by developing measures of the scope and stringency of regulation. While concern about cancer risk has played an important political role in obtaining support for pollution control programs, it has not provided the predominant rationale for most regulatory actions taken to date. Less than 20% of all standards established to limit concentrations of chemicals in various media address carcinogens. Restrictions on chemical use are more frequently based on concerns about noncancer human health or ecological effects. Of the chemicals in commercial use which have been identified as potential human carcinogens on the basis of rodent bioassays, only a small proportion are regulated. There is an inverse relationship between the scope of regulatory coverage and the stringency of regulatory requirements: the largest percentages of identified carcinogens are affected by the least stringent requirements, such as information disclosure. Standards based on de minimis cancer risk levels have been established for only 10% of identified carcinogens and are restricted to one medium: water. Complete bans on use have affected very few chemicals. The general role that carcinogenicity now plays in the regulatory process is not dramatically different from that of other adverse human health effects: if a substance is identified as a hazard, it may eventually be subject to economically achievable and technically feasible restrictions.  相似文献   
62.
In this paper, with the use of linear regressions to investigate how relationship dissolution affects sexual attitudes and behaviors, the authors address the stereotype that newly single people seek multiple sexual partners. Although the newly single people surveyed did obtain new sexual partners, the rate at which they acquired new partners did not support the stereotype. Specifically, men with custody of their children seemed oriented toward finding a steady partner. Additionally, men and women with low incomes reported relatively high rates of partner acquisition after relationship dissolution. The high rates reported by disadvantaged groups may be more directly related to familial instability accompanying poverty than to cultural characteristics associated with income or race. We argue that a life stage model with categorical stages in a rigid, anachronistic progression provides insufficient means to gain an understanding of newly single people.  相似文献   
63.
美国大学本科教育研究   总被引:14,自引:0,他引:14  
本文分析了几所著名的美国大学本科教学的课程体系及教学计划 ,总结了其基本共性 ,同时分析了各大学的教学特色。通过对各大学电子工程类专业的教学计划进行剖析 ,给出了公共基础、专业基础、专业核心、专业选修课规定的课程及学分 ,并与我国的大学本科教学计划进行比较 ,提出了我国大学本科教育应改进的几个方面。  相似文献   
64.
65.
试论国有企业改革中的人力资源管理   总被引:1,自引:0,他引:1  
本文从三个方面论述国有企业改革中的人力资源管理的必要性、重要性、变革思路,①知识经济时代要求企业增强人力资源意识;②人力资源是企业增强核心竞争力的关键;③重点从五个方面阐述国有企业人力资源管理变革的思路,即把人作为资源进行开发利用;建设高新技术产业人才发展工程;加大人力资本投资力度,全面提高人才素质;建立企业"人才仓库";建立精干、高效的人力资源管理部门,强化人力资源的管理职能.  相似文献   
66.
文章从形式逻辑角度对国有经济的概念作了辩析 ,认为国有经济是资源归国家所有的经济形式。国有资产经营方式是多样化的 ,国有企业只是国有经济的一种具体形式。  相似文献   
67.
Daughters from low‐income families who did not receive Aid to Families with Dependent Children (AFDC) are compared to daughters from low‐income families who did receive assistance to better account for family income in the intergenerational association of AFDC. The research models the timing of a daughter's first birth and, for those who become mothers, the number of years a daughter receives any AFDC. Women whose families received AFDC during their childhood are more likely to receive AFDC as adults relative to those women whose families did not receive AFDC. Controlling for family income in a more careful and comprehensive way than past research explains part but not all of the effects of childhood AFDC receipt. Among daughters from chronically poor families, however, parental AFDC use is not associated with additional years of AFDC participation. Although the present research cannot confirm or deny a causal role for parental welfare use, the intergenerational transmission of financial resources does explain part of the intergenerational association of welfare use.  相似文献   
68.
马克·吐温,这位在美国文学史上开一代创作先河的小说家,为后人留下了20多篇不朽佳作.其中,令人惊讶的是:在他全部作品中,两部描写少年历险故事的著作——《汤姆·索耶历险记》和《哈克贝里·费恩历险记》,始终处于最突出的位置,并一直被中外学者公推为其代表作.于是我们不得不深思这样一个问题,作为美国文坛杰出代表人物之一的马克·吐温为什么选择了儿童的角色,而又把他们塑造很空前成功?纵观文学界对马克·吐温作品及其人物形象的有关研究成果和论述,似乎都不能够圆满地答复这个问题.  相似文献   
69.
Gini’s nuclear family   总被引:1,自引:0,他引:1  
The purpose of this paper is to justify the use of the Gini coefficient and two close relatives for summarizing the basic information of inequality in distributions of income. To this end we employ a specific transformation of the Lorenz curve, the scaled conditional mean curve, rather than the Lorenz curve as the basic formal representation of inequality in distributions of income. The scaled conditional mean curve is shown to possess several attractive properties as an alternative interpretation of the information content of the Lorenz curve and furthermore proves to yield essential information on polarization in the population. The paper also provides asymptotic distribution results for the empirical scaled conditional mean curve and the related family of empirical measures of inequality.   相似文献   
70.
American options in discrete time can be priced by solving optimal stopping problems. This can be done by computing so-called continuation values, which we represent as regression functions defined recursively by using the continuation values of the next time step. We use Monte Carlo to generate data, and then we apply smoothing spline regression estimates to estimate the continuation values from these data. All parameters of the estimate are chosen data dependent. We present results concerning consistency and the estimates’ rate of convergence.  相似文献   
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