频率不受运放参数影响的文氏桥振荡器

本文介绍一组（12个）新的正弦振荡器，这组振荡器使用两个运算放大器，其振荡频率不受单极点有源元件增益带宽之积的影响。这种特性是由本文所介绍的电路结构取得的，即不需要调节。     

Households,history and black urbanisation: response to Graaff

A critique of a recent article by J. F. de V. Graaff concerning urbanization of blacks in South Africa is presented. A reply by Graaff (pp. 402-4) is included.     

The environment for development

This overview of the World Bank 1992 World Development Report reveals some of the means to close the gap between policy and practice in linking environmental and development policy. The nature of the problem is defined and win-win policies which show mutual support for environment and development concerns are differentiated from negative links. Sound environmental management can be achieved with improved information, enhancing institutional arrangements, and involving local people. The rapid implementation of policies and programs will involve both political and financial costs and a shift in policies and priorities. The challenges ahead are tremendous and include overcoming poverty and turning population growth and environmental pollution around. World consumption of energy and manufactured goods is expected to triple; without curbs on emissions, mortality increases, water shortages, and forest and natural habitat loss will ensue. It is not entirely true that economic activity hurts the environment when positive forces of substitution, technological innovation, and structural change outweigh the negative consequences. Environmental consequences change with income levels. Some problems decline with income increases. Some problems deteriorate temporarily and then improve as incomes rise, i.e., air and water pollution and some types of deforestation and habitat dislocation. Some problems continue to grow with income increases, such as carbon and nitrogen oxide emissions. Win-win policies are ones that foster and end to excessive resource use, clarify property rights and stop open access to land, accelerate education and family planning programs, accelerate agricultural extension and research, and invest in sanitation and water supply. These policies will not sacrifice economic growth. Tradeoffs must be identified and costs and benefits of alternative policies assessed; priorities and standards must be established in consort with costs and benefits. Behavior change can be achieved with properly designed practical and cost-effective policies.     

Combining health education, risk-rated insurance and employee rebates into an integrated health care cost management strategy

Health education, risk rating and employee rebates can be combined into a comprehensive health promotion program within a benefits plan, reflecting health promotion in its truest sense.     

The Harris-Todaro model and economies of scale

The authors attempt to reanalyze the Harris-Todaro migration model in the presence of economies of scale in the manufacturing sector, focusing on economies of scale that are external to a given firm but internal to the industry.     

中日韩自由贸易区的贸易流量和福利效应分析:一个局部均衡的校准方法

校准方法作为一种确定数理经济模型中的变量和参数的手段之一,在贸易政策的建模研究中得到广泛的应用.本文以局部均衡为基础,利用中日韩三国自1990～2003年共14年的贸易额及相关数据建立校准模型,并对拟议中的中日韩自由贸易区做出比较静态分析,从产业层面来模拟中日韩自由贸易区建成后所可能带来的福利效应.分析结果表明,中日韩三国建立自由贸易区会增加彼此的国民福利水平,并会对未加入贸易协定的其他东亚国家产生影响.因此,在东亚形成更为广泛的自由贸易安排从区域合作的角度来看是一种更佳的合作方式.     

嘉兴学院大门浮雕的设计与创意

文章介绍了嘉兴学院大门浮雕的设计理念、创作原则、表现方式与方法,并以此为基础阐释了浮雕的深刻寓意。通过“岁月如歌”“人文嘉兴”两组12块浮雕展示出嘉兴学院的文化精神、历史传承及嘉兴地域主要的人文与自然景观。     

Low-cost recruiting for quality

With a little creativity, some recruiters are turning previously overlooked applicant pools into sources of low-cost, quality hires. A look at one recruiter's program for creating a partnership with state job services.