Of Halliday's three metafunctions, the textual function helps the written or spoken text organized into a coherent one as a whole. In the textual function, the thematic structure gives the clause its character as ...Of Halliday's three metafunctions, the textual function helps the written or spoken text organized into a coherent one as a whole. In the textual function, the thematic structure gives the clause its character as a message. Since tourism has become a booming industry on the global scale, introductions to scenic spots play a crucial role in attracting or persuading readers to visit the tourist destinations. This paper, by comparing the thematic structures of two English introductions to scenic spots, tries to analyze how the writer organizes the thematic structure in English tourist tests to achieve their communicative purpose of publicizing and promotion.展开更多
Fish ectoparasites are introduced to water bodies or aquaculture systems along with their hosts. Argulid fish lice can survive off-host for a given time, and in spite of quarantine measures might also be introduced vi...Fish ectoparasites are introduced to water bodies or aquaculture systems along with their hosts. Argulid fish lice can survive off-host for a given time, and in spite of quarantine measures might also be introduced via the transfer of water. However, they must cope with varying abiotic conditions without access to food. We investigated the effect of temperature （5 to 28℃） on the off-host survival time of Argulus japonicus, an invasive species which is apparently increasing its distribution, and compared this with the European A. foliaceus. A clear effect of temperature on the off-host survival time of all stages of both species was demonstrated. Larval and juvenile A. japonicus survived up to 9 days at 22℃ and in the case of adults up to 13 days at 15℃. By comparison, larval A. foliaceus survived up to 5 days at 15℃, adults up to 14 days at 9℃ and juveniles up to 7 days at 9℃ and 15℃. Thus, A. japonicus is more resistant to starvation at higher temperatures under controlled off-host conditions and A. foli- aceus is more resistant to starvation at lower temperatures. Infectivity of A. japonicus decreased linearly with the time spent off-host after 2 days for larvae and 4 days for adults. Temperature only had a significant effect on the infectivity of both develop- mental stages after 24 hours off-host between 13-23℃ for larvae and 13-18℃ for adults. In conclusion both species can potentially survive off-host pelods in water transports for up to 13-14 days as adults. Their survival is shorter as larvae. This study demonstrates that transportation of water has the potential to introduce Argulus species展开更多
At least 1,065 introduced vertebrate species have been introduced in the United States and its territories, including at least 86 mammalian, 127 avian, 179 reptilian/amphibian, and 673 fish species. Examples in each m...At least 1,065 introduced vertebrate species have been introduced in the United States and its territories, including at least 86 mammalian, 127 avian, 179 reptilian/amphibian, and 673 fish species. Examples in each major taxonomic group include domestic cat, small Indian mongoose, red fox, goat, pig, rabbit, rats, house mouse, gray squirrel, nutria, starling, Indian common myna, red-vented bulbul, brown treesnake, red-eared slider, brown trout, tilapia, and grass carp. We briefly review some of these species and the types of damage they cause. We then review the basic types of methods used for control or eradication of each taxonomic group, including physical, chemical, biological, and cultural methods. We discuss some of the challenges in managing these species, including issues with the use of toxicants, land access, public attitudes, and monitoring difficulties. Finally, we list some ongoing research and future research needs, including improved detection methods, improved attractants, improved barriers, improved capture methods, fertility control, and risk assessment methods [Current Zoology 57 （5）： 559-567, 2011].展开更多
基于106篇TED科技演讲的语料,从修辞学的角度对开场白进行了调查,探讨如何运用修辞技巧来满足听众的需求。学者Dorien Van De Mieroop的开场白模型将修辞技巧分为三个主要功能:attentium、benevolum和docilem。研究表明,attentium使用最...基于106篇TED科技演讲的语料,从修辞学的角度对开场白进行了调查,探讨如何运用修辞技巧来满足听众的需求。学者Dorien Van De Mieroop的开场白模型将修辞技巧分为三个主要功能:attentium、benevolum和docilem。研究表明,attentium使用最多,docilem次之,benevolum第三。约一半的演讲者在开场白部分使用了三类功能下的不止一种技巧,而完整运用三种修辞功能的开场白很少。该结果说明了TED科技演讲的实用性和科普功能,其技巧的选择取决于演讲的内容与主旨,以及演讲者的风格。最后对开场白模型进行了评价,并对研究的教学意义进行了讨论。展开更多
Inland waters are highly vulnerable to the introduction and spread of non-native species,due to heavy human use of aquatic ecosystems and the natural linkages among streams and lakes.This is particularly noticeable in...Inland waters are highly vulnerable to the introduction and spread of non-native species,due to heavy human use of aquatic ecosystems and the natural linkages among streams and lakes.This is particularly noticeable in freshwater fish communities.To better evaluate how these communities are affected by non-native species introductions,we conducted a fine-scale analysis of the changes in Italian freshwater fish assemblages after species introduction.For this analysis,we collected information on fish species present in 44 basins.The present Italian freshwater fish fauna is composed of 48 native and 41 established introduced species,while a further 15 introduced species have been reported but are not yet considered naturalized.The changes in the fish assemblages mostly took place in the past 2 centuries and have increased recently,with nearly 60%of the species introduced in the past 3 decades.The number of species introduced per basin ranged from 0 to 35(mean 10.85±7.77 species/basin),and in 10 basins the number of species introduced is now equal to or even higher than the number of native species.In the past,introduced species mainly originated from America,but over the past three decades,an increase of introductions from other parts of Europe and Asia has been recorded.Our results show that basins already rich in native species tend to become even richer as a consequence of the establishment of introduced species.This confirms the trend toward a biotic homogenization of ecosystems even at a local scale,due to an increase in the human-mediated spread of generalist species.展开更多
文摘Of Halliday's three metafunctions, the textual function helps the written or spoken text organized into a coherent one as a whole. In the textual function, the thematic structure gives the clause its character as a message. Since tourism has become a booming industry on the global scale, introductions to scenic spots play a crucial role in attracting or persuading readers to visit the tourist destinations. This paper, by comparing the thematic structures of two English introductions to scenic spots, tries to analyze how the writer organizes the thematic structure in English tourist tests to achieve their communicative purpose of publicizing and promotion.
文摘Fish ectoparasites are introduced to water bodies or aquaculture systems along with their hosts. Argulid fish lice can survive off-host for a given time, and in spite of quarantine measures might also be introduced via the transfer of water. However, they must cope with varying abiotic conditions without access to food. We investigated the effect of temperature （5 to 28℃） on the off-host survival time of Argulus japonicus, an invasive species which is apparently increasing its distribution, and compared this with the European A. foliaceus. A clear effect of temperature on the off-host survival time of all stages of both species was demonstrated. Larval and juvenile A. japonicus survived up to 9 days at 22℃ and in the case of adults up to 13 days at 15℃. By comparison, larval A. foliaceus survived up to 5 days at 15℃, adults up to 14 days at 9℃ and juveniles up to 7 days at 9℃ and 15℃. Thus, A. japonicus is more resistant to starvation at higher temperatures under controlled off-host conditions and A. foli- aceus is more resistant to starvation at lower temperatures. Infectivity of A. japonicus decreased linearly with the time spent off-host after 2 days for larvae and 4 days for adults. Temperature only had a significant effect on the infectivity of both develop- mental stages after 24 hours off-host between 13-23℃ for larvae and 13-18℃ for adults. In conclusion both species can potentially survive off-host pelods in water transports for up to 13-14 days as adults. Their survival is shorter as larvae. This study demonstrates that transportation of water has the potential to introduce Argulus species
文摘At least 1,065 introduced vertebrate species have been introduced in the United States and its territories, including at least 86 mammalian, 127 avian, 179 reptilian/amphibian, and 673 fish species. Examples in each major taxonomic group include domestic cat, small Indian mongoose, red fox, goat, pig, rabbit, rats, house mouse, gray squirrel, nutria, starling, Indian common myna, red-vented bulbul, brown treesnake, red-eared slider, brown trout, tilapia, and grass carp. We briefly review some of these species and the types of damage they cause. We then review the basic types of methods used for control or eradication of each taxonomic group, including physical, chemical, biological, and cultural methods. We discuss some of the challenges in managing these species, including issues with the use of toxicants, land access, public attitudes, and monitoring difficulties. Finally, we list some ongoing research and future research needs, including improved detection methods, improved attractants, improved barriers, improved capture methods, fertility control, and risk assessment methods [Current Zoology 57 （5）： 559-567, 2011].
文摘基于106篇TED科技演讲的语料,从修辞学的角度对开场白进行了调查,探讨如何运用修辞技巧来满足听众的需求。学者Dorien Van De Mieroop的开场白模型将修辞技巧分为三个主要功能:attentium、benevolum和docilem。研究表明,attentium使用最多,docilem次之,benevolum第三。约一半的演讲者在开场白部分使用了三类功能下的不止一种技巧,而完整运用三种修辞功能的开场白很少。该结果说明了TED科技演讲的实用性和科普功能,其技巧的选择取决于演讲的内容与主旨,以及演讲者的风格。最后对开场白模型进行了评价,并对研究的教学意义进行了讨论。
文摘Inland waters are highly vulnerable to the introduction and spread of non-native species,due to heavy human use of aquatic ecosystems and the natural linkages among streams and lakes.This is particularly noticeable in freshwater fish communities.To better evaluate how these communities are affected by non-native species introductions,we conducted a fine-scale analysis of the changes in Italian freshwater fish assemblages after species introduction.For this analysis,we collected information on fish species present in 44 basins.The present Italian freshwater fish fauna is composed of 48 native and 41 established introduced species,while a further 15 introduced species have been reported but are not yet considered naturalized.The changes in the fish assemblages mostly took place in the past 2 centuries and have increased recently,with nearly 60%of the species introduced in the past 3 decades.The number of species introduced per basin ranged from 0 to 35(mean 10.85±7.77 species/basin),and in 10 basins the number of species introduced is now equal to or even higher than the number of native species.In the past,introduced species mainly originated from America,but over the past three decades,an increase of introductions from other parts of Europe and Asia has been recorded.Our results show that basins already rich in native species tend to become even richer as a consequence of the establishment of introduced species.This confirms the trend toward a biotic homogenization of ecosystems even at a local scale,due to an increase in the human-mediated spread of generalist species.
