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HOCKETT CF 《American scientist》1948,36(4):558-572
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中国和印度几乎同时出现在世界舞台表明国际事务的架构发生了史无前例的变化.这两个占世界人口40%的巨人,其人口相当于位居其后的20个人口最多国家的人口总和.在十九和二十世纪,这两个巨人长期在主宰国际事务的欧洲、日本和美国的阴影之下沉睡. 相似文献
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<正>位于利马气候大会会场F区附近的一片草坪上,人们常常能看到很多中国人的面孔。每天中午1点多的时候,中国代表团的团员们会陆陆续续来到这里领取盒饭,稀里哗啦地吃完之后,坐在塑料椅子上稍微休息一会儿。12月的利马炎热异常,草坪上的树荫下稍微凉快一点,比帐篷和板房搭起来的办公室要好多了。所以,大会没开始几天,中国角的媒体吹风会就改到了这片草坪上,几张拼起来的折叠桌和一圈塑料椅子就 相似文献
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This paper applies several well-known decision criteria to the climate change problem. The policy process is represented by a simple game against nature with two possible choices: abate or no action. The outcome is considered a compound lottery, with one representing emissions and another representing damages. Assuming that costs exceed benefits of abatement for the participant, the paper analyzes how different decision criteria affect the decision to abate. The role of expert opinion and quality of information in climate change decisions are also considered. The complexity of global warming makes it impossible to completely overlook the consequences of alternative choices. The paper discusses the question of whether the use of less information demanding alternatives to expected utility theory is indicated. It concludes that the choice of criterion is a political question, and that those in favor of abatement policies might be using one of the alternatives as basis for their advice, and suggests that if the possibility of making irreversible mistakes is of great concern, then the minimax regret criterion might have increased relevance. 相似文献
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Investigation on Fe, Mn, Zn, Cu, Pb and Cd fractions in the natural surface coating samples and surficial sediments in the Songhua River, China 总被引:3,自引:0,他引:3
Natural surface coating samples (NSCSs) from the surface of shingles and surficial sediments (SSs) in the Songhua River, China were employed to investigate the relationship between NSCSs and SSs in fractions of heavy metals (Fe, Mn, Zn, Cu, Pb, and Cd) using the modified sequential extraction procedure (MSEP). The results show that the differences between NSCSs and SSs in Fe fi'actions were insignificant and Fe was dominantly present as residual phase (76.22% for NSCSs and 80.88% for SSs) and Fe-oxides phase (20.33% for NSCSs and 16.15% for SSs). Significant variation of Mn distribution patterns between NSCSs and SSs was observed with Mn in NSCSs mainly present in Mn-oxides phase (48.27%) and that in SSs present as residual phase (45.44%). Zn, Cu, Pb and Cd were found dominantly in residual fractions (〉48%), and next in solid oxides/hydroxides for Zn, Pb and Cd and in easily oxidizable solids/compounds form for Cu, respectively. The heavy metal distribution patterns implied that Fe/Mn oxides both in NSCSs and SSs were more important sinks for binding and adsorption of Zn, Pb and Cd than organic matter (OM), and inversely, higher affinity of Cu to OM than Fe/Mn oxides in NSCSs and SSs was obtained. Meanwhile, it was found that the distributions of heavy metals in NSCSs and SSs were similar to each other and the pseudo-total concentrations of Zn, Cu, Pb and Cd in NSCSs were greater than those in SSs, highlighting the more importance for NSCSs than SSs in controlling behaviours of heavy metals in aquatic environments. 相似文献
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在旱季,亚马孙河巨龟(Podocnemis
expansa)将巢穴修筑在河槽边缘和内部的广阔沙洲上.这些巢穴在某些沙滩上的某些具体地点的大量聚集表明巢穴位置的选择不是随机的,而是与一些地质状况有关,如沙洲边缘的倾斜度和砂质高台的存在.通向高台顶端的通道或斜坡结构的存在是巢穴位置选择的决定性因素.被侵蚀的以及陡峭的沙滩边缘阻碍了亚马孙河龟到达最理想的筑巢位置.随着时间的推移,沙滩形态的变化会改变巢穴的分布. 相似文献