关于电子商务运作案例的讨论     

李超 《成都信息工程学院学报》2000,15(4):285-291

介绍了上海证券交易所、苏州商品交易所的电子商务运作。并着重讨论了中国商品交易中心系统的设计与方案 ,论述了信息发布与查询、网上谈判与合同管理的具体运作  相似文献   

Trade intervention: Not a silver bullet to address environmental externalities in global aquaculture     

《Marine Policy》2016

Aquaculture has been the world’s fastest growing food production technology in recent decades, and continued growth in aquaculture production is predicted. While creating economic opportunity, aquaculture is also a new way of using eco-systems, and there is substantial evidence that aquaculture creates negative environmental externalities. Although the most effective way to address these externalities may be improved governance, this approach is often difficult because most aquaculture production takes place in developing countries with limited management capacity. The fact that a large part of aquaculture production is traded motivates substantial interest in the use of trade measures to reduce environmental impacts. However, the wide variety of species, production practices, and governance systems present in aquaculture makes it unlikely that general trade measures will achieve environmental objectives. Rather, there is a real risk that trade measures will reduce economic opportunity, raise new equity concerns, and impinge on public health with little or no environmental impact.  相似文献   

Is the Northern Sea Route attractive to shipping companies? Some insights from recent ship traffic data     

《Marine Policy》2016

While the media vigorously propagates historic Northern Sea Route (NSR) transits and researchers demonstrate the viability of the NSR, current usage by the shipping industry has been neglected thus far. This study aims to analyse the current ship traffic at NSR using transit data and port call data. The results show that navigation season lasts for five months, and Arc4 and Arc5 vessels are used extensively. Some Asian countries are active participants in the transit activities. NSR seems to be more appealing to liquid, bulk and general cargo transportation. Currently, most activities are still domestic and destinational in nature. The paper provides real statistics that can add value to the viability analysis. It identifies key players of the transits, exhibits trade pattern at NSR, and presents facts that interest shipping companies.  相似文献   

Visa restrictions and economic globalisation     

《Applied geography (Sevenoaks, England)》2017

The cross-border mobility of people, goods and services, and capital has expanded enormously both in intensity and diversity over recent decades. States have a general interest in facilitating these flows in order to benefit from economic globalisation. Yet, mainly due to security concerns, most governments grant visa-free mobility only very selectively. Drawing on a new bilateral visa policy database covering up to 194 destination and 214 origin countries over the 1995 to 2013 period, our analysis finds that the introduction of a visa restriction by a destination country for citizens from a particular origin country deters tourism inflows by about 20 per cent. Visa restrictions also reduce bilateral trade and foreign investment, but to a smaller extent than previous studies have suggested. We further find that some of the deterred flows in tourists and goods and services are redirected to other (visa-free) destinations. This deterrence-cum-deflection effect of restrictive visa policies implies significant economic costs for both visa-issuing and visa-targeted countries, but it creates some positive externalities for countries with a more liberal visa policy. Liberalised visa policies would in particular help poorer countries to partake more in the benefits of economic globalisation.  相似文献   

Chemical contamination of the Hudson-Raritan Estuary as a result of the attack on the World Trade Center: analysis of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in mussels and sediment     

Lauenstein GG  Kimbrough KL 《Marine pollution bulletin》2007,54(3):284-294

The September 11, 2001 attack on the World Trade Center (WTC) resulted in a massive plume of dust and smoke that blanketed lower Manhattan and part of the Hudson-Raritan Estuary (HRE). The NOAA National Status and Trends Mussel Watch Program has long-term monitoring sites in the area and thus had an opportunity to assess the effect of the WTC attack on PAH and PCB contamination of the surrounding estuary. Seven additional sites were added in the Upper HRE to attain higher sampling resolution for comparison with regularly sampled Mussel Watch Project HRE sites. Elevated background levels of PCBs and PAHs in mussel tissue and sediments were high enough before the WTC attack that concentrations were not measurably changed by WTC derived contaminant input.  相似文献   

Initiation and early development of barchan dunes: A case study of the Moroccan Atlantic Sahara desert   总被引：1，自引：0，他引：1  

Hicham Elbelrhiti 《Geomorphology》2012,138(1):181-188

This paper describes field measurements that document the formation of barchan dunes in the Moroccan Atlantic Sahara desert. The first mechanism described is the transformation of patches and proto-dunes at Cap Juby beach to barchan dunes of elementary size. This transformation is discussed in relation to the wind speed and saturation length. The second mechanism is the ejection of small barchans of elementary size by other small barchans in response to the perturbation of the target barchan by two other impacting small barchans. This remote initiation is discussed in relation to the bulk flux transported by the barchan dunes involved in this interaction and to their morphology. Other modes of barchan initiation observed in the field are also presented.  相似文献   

Mesoscale Structure of Trade Wind Convection over Puerto Rico: Composite Observations and Numerical Simulation     

Mark R. Jury  Sen Chiao  Eric W. Harmsen 《Boundary-Layer Meteorology》2009,132(2):289-313

We examine the mesoscale structure of the atmospheric boundary layer (ABL), low-level circulation, and trade wind convection over the sub-tropical island of Puerto Rico in mid-summer. Shallow afternoon thunderstorms are frequently seen over the western plains of the island. Observational data include automatic weather station measurements, radiosonde profiles, infrared satellite images, and mesoscale reanalysis data with a focus on the summer of 2006. Satellite microwave radar data (TRMM and CloudSat) indicate that island clouds typically extend just above the −20°C level during afternoon hours with reflectivity values reaching 50 dBz. A singular value decomposition of 3-hourly high resolution satellite rainfall maps reveals an island mode. From this a composite is constructed for a group of ten cases. With a Froude number ≈1 the trade winds pass over the mountains and standing vortices and gravity waves are trapped in the meandering wake. The Weather and Research Forecasting (WRF) model at 1-km resolution with 51 vertical layers is used to simulate the short-lived thunderstorms for two cases: 27 June and 20 July 2006. The model correctly locates the convective cells that develop between 1400 and 1700 LST. The shallow afternoon thunderstorms are triggered by surface heat fluxes, confluent sea breezes and a mountain wake. Recommendations for enhanced observations are given.  相似文献   

版纳勐养保护区鸟类及人为影响分析   总被引：1，自引：0，他引：1  

王直军  贾知行 《云南地理环境研究》1994,6(1):78-83

切实保护和利用好西双版纳现存热带森林，是急需处理的现实问题。本文通过勐养自然保护区鸟类调查结果，揭示了西双版纳保护区管理现状。多数地区实际上未管理起来，林区居民仍滥用自然资源，对鸟类的猎捕从未停止，有的地方颇为严重；从生物多样性着眼，环境质量在下降。现已管理起来的三岔河保护区，尽管旅游开放后尚存许多问题亟待探索和改进，但鸟类保护状况已明显改善，说明自然保护区旅游在科学管理下才是可行的。就此，本文分析、评价了勐养保护区鸟类受人为影响情况，对自然保护区管理工作提出建议。  相似文献   

Benefits from increased cooperation and energy trade under CO₂ commitments—The Nordic case     

Thomas Unger  Tomas Ekvall 《Climate Policy》2003,3(3):279-294

In this paper, benefits from increasing cross-border cooperation under future CO₂ commitments in the Nordic countries are examined and evaluated. Four cooperative strategies are analyzed and valued separately: cross-border electricity trade, cross-border emission-permit trade, the introduction of a trans-Nordic natural gas transmission grid, and, finally, utilization of all these three strategies simultaneously. The valuation is done under varying CO₂ commitments and under three different scenarios for future energy demand and technological development. In conducting this analysis, the energy-systems model-generator MARKAL (MARKet ALlocation) was used to model the Nordic energy system. It is shown that all cooperative strategies do lower the abatement costs considerably, especially if the strategy including full cooperation is utilized. In this case, additional costs from meeting CO₂ targets may be at least halved for commitments less than 10% reduction until 2050 based on emissions in 1995. No significant difference between low and high CO₂ commitments could be observed in the size of the benefits from cooperation, expressed in billions (10⁹) of Swedish crowns. Benefits from cooperation are generally larger for scenarios including relatively higher future energy demand.  相似文献   

东莞工业行业特征分析及展望   总被引：1，自引：0，他引：1  

王云璇  马跃东  阎小培 《热带地理》2002,22(3):199-203

针对以往的研究普遍偏重对工业结构进行全面分析，而相对较少对行业特征进行深入研究的状况，从工业行业结构的角度，分析和总结东莞工业行业发展特征，空间分布特征，旨在探讨开放条件下，外资带动工业化发展模式的发展轨迹，为我国区域发展提供一种思路，从1985到1999年，东莞工为行业结构变化显著，主导行业向新兴行业转移且集中程度提高，仍以制造业为主，电子业突出，行业地位位不高；行业总体分布较分散。主要行业有一定的集中趋势。  相似文献