“绿色贸易堡垒”与经济发展的“绿色通行证”

“绿色贸易堡垒”是国际贸易中非关税贸易堡垒重要的组成部分，它从保护环境的目的出发，在国际贸易中发挥着越来越重要的作用。文章通过对天津市现实状况的研究，提出克服绿色贸易堡垒，为天津市经济在入世后获得“绿色通行证”的对策建议。     

包装行业中的变频器矢量控制技术

为了更好地解决包装行业中电力拖动设备的机械性能和调速问题,选用了矢量控制型变频器．介绍了变频器矢量控制的基本原理,并且建立了异步电动机在不同坐标系下的数学模型．最后采用磁场定向控制方法,导出了异步电动机的矢量控制数学模型,方便了变频器矢量控制的实现．图1,参4．     

Contribution of the Live-Vertebrate Trade toward Taxonomic Homogenization

Abstract:  The process of taxonomic homogenization occurs through two mechanisms, extinctions and introductions, and leads to a reduction of global biodiversity. We used available U.S. trade data as a proxy for global trade in live vertebrates to assess the contribution of trade to the process of taxonomic homogenization. Data included all available U.S. importation and exportation records, estimation of extinction risk, and reports of establishment outside the native range for species within six vertebrate groups. Based on Monte Carlo sampling, the number of species traded, established outside of the native range, and threatened with extinction was not randomly distributed among vertebrate families. Twenty-eight percent of vertebrate families that were traded preferentially were also established or threatened with extinction, an unusually high percentage compared with the 7% of families that were not traded preferentially but that became established or threatened with extinction. The importance of trade in homogenization of vertebrates suggests that additional efforts should be made to prevent introductions and extinctions through this medium.     

Trade and Transboundary Pollution: Spatial Separation Reconsidered

Copeland and Taylor (1999, J. Int. Econ.47, 137–168) show that trade allows the spatial separation of two incompatible industries. Concentrating the polluting industry in one country eliminates its degenerative effects in the other. This paper extends the analysis by allowing for transboundary pollution. Thus specialization has indirect repercussions on the level of pollution in the other country. We show (i) how cross-national differences in exposure to pollution emissions can generate comparative advantage and (ii) under what condition the resulting trading pattern combined with transboundary pollution can increase pollution exposure with negative effects on productivity and welfare in both countries.     

Discrepancies in Reported Levels of International Wildlife Trade

Abstract:  The international wildlife trade is a principal cause of biodiversity loss, involving hundreds of millions of plants and animals each year, yet wildlife trade records are notoriously unreliable. We assessed the precision of wildlife trade reports for the United States, the world's largest consumer of endangered wildlife, by comparing data from the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) with U.S. Customs data. For both U.S. imports and exports, CITES and Customs reported substantially different trade volumes for all taxa in all years. Discrepancies ranged from a CITES-reported volume 376% greater than that reported by Customs (live coral imports, 2000) to a Customs' report 5202% greater than CITES (conch exports, 2000). These widely divergent data suggest widespread inaccuracies that may distort the perceived risk of targeted wildlife exploitation, leading to misallocation of management resources and less effective conservation strategies. Conservation scientists and practitioners should reexamine assumptions regarding the significance of the international wildlife trade.     

Free Trade Is Green, Protectionism Is Not

Many writers argue that free trade will lead to environmental degradation. Most environmentally pernicious public policies, however, such as subsidies of timber extraction and ranching, are also trade protectionist policies. To the extent that free trade treaties, such as the General Agreement on Tariffs and Trade, do away with such trade protectionism, free trade instead could be viewed as a major pathway to environmental reform. Furthermore, trade liberalization is associated with urbanization and industrialization, both of which reduce population growth rates and the pressures of colonization. I suggest that we, as environmentalists, can ally ourselves with free traders.     

The Horticultural Trade and Ornamental Plant Invasions in Britain

Abstract:  Ornamental horticulture has been recognized as the main pathway for plant invasions worldwide. We examined the link between propagule pressure created by the presence of ornamental plants in the market and their ability to escape from cultivation and establish in the wild. A random sample of 534 non-native ornamental species on sale in nineteenth century Britain showed that 27% of these species were recorded growing outside cultivation and 30% of those were established. Species that had escaped from cultivation were more frequently on sale both in the nineteenth century and today than nonescaping species. We used logit regression models to identify biological and socioeconomic variables that affect species' abilities to escape cultivation and become established. Frequencies in the market in the nineteenth century and today were good explanatory variables that distinguished escaping from nonescaping species, whereas for the transition from casual to established status these two socioeconomic variables were either absent or only of weak significance. Biological characteristics that increased the probability that a species would escape from cultivation were species height, a European native range, and being an annual. Climbing plants and species intolerant of low temperatures were less likely to escape. In contrast, the establishment probability was greater if the species belonged to a genus native to Britain and increased as the number of continents in a plant's native range increased. Annual plants had a reduced probability of establishment. Market presence, prices, and the date of introduction are among the socioeconomic factors that have had important effects on the observed course of invasions.     

反倾销:出口贸易的障碍及对策

改革开放以来，中国成了全球最大的反倾销受害国．频遭反倾销指控，对我国的出口贸易和国民经济造成了极大的损失．对此，我国一方面要尽力扭转国际上对我国的一系列歧视性做法，一方面深化国内外贸管理体制改革，提高出口企业的产品质量和应诉能力等，以更快适应WTO的贸易规则，在国际反倾销战中赢得主动．     

International Trade Status and Crisis for Snake Species in China

Abstract:  In recent years, the purchase of snakes for leather, food, and traditional medicine has increased in China, which has greatly reduced certain snake populations. Trade records show that since the 1990s, with respect to some species of snakes, China is changing from a net export country to a net import country. We analyzed data on international trade in snake species, concentrating, in particular, on trade dynamics and species composition. The overall number of snakes exported appears to have decreased in the last 10 years. However, the number of snakes imported during this period has increased steadily. Many species of snakes that are traded in significant numbers are endangered or threatened species. To conserve snakes in China, we recommended that the Chinese government and the international conservation community take the following actions: enhance legislation and list several species in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) appendices; register all snake farms in China; carry out population and market surveys; monitor the dynamics of trade; encourage biological research; encourage change in food habits; and enhance cooperation between Hong Kong and mainland China.     

Global Trade in Exotic Pets 2006–2012

International trade in exotic pets is an important and increasing driver of biodiversity loss and often compromises the standards required for good animal welfare. We systematically reviewed the scientific and gray literature and used the United Nations Environment Programme ‐ World Conservation Monitoring Centre (UNEP‐WCMC) Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) trade database to establish temporal and geographical trade patterns of live exotic birds, mammals, and reptiles and to describe trends in research, taxonomic representation, and level of threat and legal protection of species traded. Birds were the most species‐rich and abundant class reported in trade; reptiles were second most abundant but unusually the most studied in this context; and mammals were least abundant in trade. Mammalian and reptilian species traded as pets were more likely to be threatened than expected by random. There have been a substantial number of Appendix I listed captive‐bred mammals and birds and wild‐caught birds and reptiles reported in trade to CITES. We identified the Middle East's emerging role as a driver of demand for exotic pets of all taxa alongside the well‐established and increasing role of South America and Southeast Asia in the market. Europe, North America, and the Middle East featured most heavily in trade reports to CITES, whereas trade involving South America and Southeast Asia were given most emphasis in the literature. For effective monitoring of and appropriate response to the international exotic pet trade, it is imperative that the reliability and detail of CITES trade reports improve and that scientific research be directed toward those taxa and locations that are most vulnerable. El Mercado Global de Mascotas Exóticas 2006‐2012