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谈“产生性技能”在外语教学中能力的培养
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作者 林明萍 《海南矿冶》 2001年第2期42-43,共2页
关键词 产生性技能 外语教学 信息差 语言输入 交际活动 外语学习 可理解 “合作原则” 交际能力 语言习得
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从语言测试角度分析CET简答题的语篇和应试技巧
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作者 傅晓恒 吴冬梅 《赣南师范学院学报》 2002年第5期140-143,共4页
简短回答问题是大学英语等级考试新增设的一项测试类型 ,其测试重点为考生的语言能力和语言组织能力。文章从语言测试角度分析简答类题形对考生语篇能力的要求 。
关键词 语篇能力 产生性技能 接受技能 隐含意义 CET简答题 语言测试 大学英语等级考试
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Two Bandwidth Packing Algorithms for the Centralized Wireless Network and Their Average-case Analysis 被引量:1
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作者 陈建新 龚玲 +1 位作者 杨宇航 曾鹏 《Journal of Shanghai Jiaotong university(Science)》 EI 2007年第3期397-404,共8页
This paper presents a detail analysis of two bandwidth packing algorithms, used for processing connection requests in the centralized wireless network. Each call comes with a specific bandwidth request. A request can ... This paper presents a detail analysis of two bandwidth packing algorithms, used for processing connection requests in the centralized wireless network. Each call comes with a specific bandwidth request. A request can be satisfied only if there is sufficient bandwidth available during resource scheduling and allocation. Unsatisfied requests were held in a queue. The metric of bandwidth utilization ratio was used to quantify the performance of our algorithms. By theoretical analysis, our algorithms can improve the average bandwidth usage ratio significantly, about 8%~10% without adding much computation complexity. Moreover, our algorithms outperform next fit with fragmentation (NFF) algorithm when the bandwidth resource is scarce. In this paper, the contributions follows: Introducing bandwidth packing problem into wireless network; Proposing two new bandwidth packing algorithms for wireless network where the complicate scheduling algorithms are prohibited; Studying the average performance of our algorithms mathematically, which agree well with the simulation results. 展开更多
关键词 wireless network average performance bandwidth packing problem (BWP)
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Contribution for a Better Understanding of the Technological Sustainability in Electrical Energy Production through Photovoltaic Cells
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作者 R.P. Mendes L.C. Goncalves P.D. Gaspar 《Journal of Energy and Power Engineering》 2011年第6期542-547,共6页
The conversion of solar energyinto electricity reveals a huge importance in the production of"clean" energy, mainly when applied to decentralized production systems (micro-generation). However, there is the need t... The conversion of solar energyinto electricity reveals a huge importance in the production of"clean" energy, mainly when applied to decentralized production systems (micro-generation). However, there is the need to develop and optimize these processes in order to turn it more sustainable in economic and technological scoops. The main purpose of this work is to study the solar energy conversion into electricity through photovoltaic cells, characterizing the process efficiencies. This study intends to evaluate the energetic and exergetic efficiencies defining them as indicators in the formulation ofa sustainability index. All the procedures are in a theoretical scope with an illustrative example in the end of this work. 展开更多
关键词 Sustainability index energy EXERGY photovoltaic indicators.
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Technological Properties of Yeast Produced Surface Active Compounds in Connection with Their Application in Clean-Up Technologies
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作者 Kristina Lhotska Marek Sir +2 位作者 Jiri Mikes Zuzana Honzajkova Miroslav Minarik 《Journal of Agricultural Science and Technology(A)》 2014年第1期49-59,共11页
Biologically produced surfactants (SACs) can mobilize and solubilize non-aqueous phase liquids (NAPL) adsorbed onto soil constituents. The interest in microbial surfactants has increased during recent years due to... Biologically produced surfactants (SACs) can mobilize and solubilize non-aqueous phase liquids (NAPL) adsorbed onto soil constituents. The interest in microbial surfactants has increased during recent years due to their lower toxicity, higher biodegradability, selectivity and specific activity under extreme conditions than synthetic SACs. Main output of the project represents preparation of this yeast biosurfactant intended for washing of matrices contaminated by NAPL. The influence of cultivation media composition on biosurfactant production was studied and basic properties (critical micelle concentration (CMC), minimum surface tension) of isolated biosurfactants were compared with properties of synthetic surfactant with surface tension measurement. The interracial tension of the systems containing aqueous solutions of different concentrations and non-polar substances was measured with petroleum compounds (kerosene Jet A-l), aromatic and aliphatic hydrocarbons (represented by toluene and hexane). The solution of biosurfactant Yarrowia lipolytica (YAR) in the concentration range of 0-500 mg/L reduced interracial tension by 80% in all representative systems with model contaminants; biosurfactant Candida bombicola (CAN) was less efficient. Solubilization properties were proved with toluene and hexachlorocyclohexane (HCH) isomers alpha and gamma, and effective concentration of biosurfactants was determined as 100 mg/L for toluene and HCH. SACs produced by lipophilic yeast with non-toxic and non-pathogenic status (Yarrowia lipolytica, Candida sp., etc.) seem to be very promising. The results obtained will be used for the application of biosurfactants in the clean-up technologies as agents for the mobilization of non-polar contaminants as well as for stimulation of bioremediation processes. 展开更多
关键词 Biological surfactant lipophilic yeast carbon source soil washing.
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Advantages and Disadvantages of Transgenic Animal Technology with Genetic Engineering
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作者 Mine Dosay-Akbulut 《Journal of Agricultural Science and Technology(A)》 2014年第2期177-187,共11页
Transgenic animal technology has been one of the fastest growing biotechnology areas. The exogenous genes have been introduced into the animal genome by genetic engineering, so that these genes can be inherited and ex... Transgenic animal technology has been one of the fastest growing biotechnology areas. The exogenous genes have been introduced into the animal genome by genetic engineering, so that these genes can be inherited and expressed by offspring to produce desired traits or evaluate function in elite livestock breeds. There are several methodologies for the production of transgenic animals, i.e., (1) microinjection of genes into pronuclei of fertilized ova; (2) DNA transfer by retroviruses; (3) injection of embryonic germ (EG)/embryonic stem (ES) cells previously treated with foreign DNA; (4) DNA transfer into cells and embryos with using liposomes; (5) exogenous DNA transfer while in vitro fertilization by using sperm; (6) electroporation of DNA into sperm, embryos or ova; (7) biolistics; (8) nuclear transfer (NT) with somatic cells, EG or ES cells; (9) germ line stem cell-mediated; (10) gene targeting; (! 1) gene silencing technology with RNA interference; (12) induced pluripotent stem cell; (13) zinc-finger nuclease gene targeting technology. Gene farming is one of the newest and most promising areas in modern biotechnology. Cattle, goats, sheep, pigs and rabbits are the main farm livestock species and fish is also used in transgenic technology. The question of "why make transgenic animals?" is very important. Some of the answers to this question are: (1) to obtain new knowledge; (2) to solve the genetic code; (3) to create genetic disease models; (4) to study the genetic control of physiological systems; (5) to improve animal production traits; (6) to produce new animal products. Transgenic technology is one of the main and important tools in the finding solutions to problems of growing population with their applications to different organisms, and takes more attention and interest every day. Transgenic technology creates opportunities and areas to play with organisms to fulfill the demands of people. Because of this, this paper based on mainly transgenic applications to take people's attention and exhibit its importance. 展开更多
关键词 BIOTECHNOLOGY bioreactors LIVESTOCK TRANSGENIC ANIMAL genetic engineering
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