基于MATLAB的信号与系统软件实验平台

基于MATLAB软件的信号与系统实验平台,弥补了教学中的不足,通过实验,加强学生对信号与系统课程的理解和掌握。     

Degradation of pyrene and characterization of<Emphasis Type="Italic">Saccharothrix</Emphasis> sp. PYX-6 from the oligotrophic Tianchi Lake in Xinjiang Uygur Autonomous Region,China

Bacterial strain PYX-6 that utilizes anthracene,phenanthrene, or pyrene for carbon and energy sources for growth was isolated from a non-polluted lake (Tianchi Lake) in Xinjiang Uygur Autonomous Region of China. Its morphology, physiological and biochemical properties, cell wall pattern and G C mol% content of DNA molecules were characterized. The 16S rRNA gene of strain PYX-6 was sequenced and analyzed for similarities to related bacterial species. Results indicated that strain PYX-6 is a member of the Genus Saccharothrix, and the strain was named Saccha-rothrix sp. PYX-6. When pyrene was the sole carbon source in cultural medium, the strain PYX-6 assimilated pyrene for growth and 0.005% of yeast extract stimulated pyrene degradation and assimilation. The optimal pH of cultural medium and the optimal shaking frequency during cultivation were 6-8 and 200 r/m, respectively. It was found that the disappearance of pyrene in medium occurred before significant growth of strain PYX-6 took place. Phthalic acid, benzylacetic acid, and benzylpropenoic acid were detected as catabolic intermediates during pyrene degradation with mass spectroscopy and this result indicated that Saccharothrix sp.PYX-6 adopted a pathway that is different from the pathway of the previously reported pyrene-degrading Mycobacterium sp. PYR-1.     

巴比妥酸互变异构的理论计算

采用B3LYP/6-311G**方法对处于优势构象时的巴比妥酸各互变异构体进行了几何全优化和频率计算,CPCM反应场溶剂模型用于水相的计算,得到它们的总能量、零点振动能和溶剂化能.计算结果表明,巴比妥酸在气相中和水相中主要以酮式结构存在.采用相同方法计算并考察了烯醇式与酮式结构进行结构互变质子迁移的2种可能途径:(a)分子内质子迁移;(b)水助质子迁移.结果还表明,途经(b)所需要的活化能较小,氢键在降低反应活化能方面起着重要作用.     

基于GIS的内蒙古中部区域洪水灾害风险评价

本文综合考虑自然以及社会的作用,从洪水危险性和社会易损性两个角度出发,选取地理高程、人口密度、人均GDP和历史灾情数据为指标,采用快易的叠加分析法对研究区(内蒙古中部)进行区域洪水灾害风险评价,实现了各种指标定性与定量的组合,得出研究区洪水灾害风险评价图.结果表明,研究区南部靠近黄河的河套平原地区,由于地势较为平缓、靠近河流、经济发达,洪水灾害风险较大.在研究区北部,由于经济不发达,人口较少,洪水灾害风险较小.与实际基本相符.     

双语创作的文化困惑及其意义(下篇)——从哈萨克女作家哈依霞、叶尔克西的创作谈起

哈萨克女作家哈依霞.塔巴热克和叶尔克西.胡尔曼别克是运用双语创作、双语思维、具有多元文化视角的优秀哈萨克女作家。在本民族与汉民族文化心理态势重铸的选择中,她们的创作既有融合、认同,又有矛盾、困惑;既充分展示了哈萨克民族文化的神韵和个性,又广采博收,汲取人类多元文化的有益养分,具有超越民族界限的哲理思考;她们的创作实绩证明了多元文化视角对于弘扬民族文化、发展民族文学有着重要意义。在对她们文学创作多元视角文化优势的充分肯定的基础上(见上篇),本文着重通过对她们文本的解读,阐释少数民族作家双语创作的文化困惑及其意义。     

Recent temperature increase recorded in an ice core in the source region of Yangtze River

Interests on climate change in the source region of Yangtze River have been raised since it is a region with the greatest warming over the Tibetan Plateau (TP). A 70-year history of precipitation δ~(18)O has been recovered using an ice core record retrieved in a plat portion of the firn area in the Guoqu Glacier (33°34′37.8″N, 91°10′35.3″E, 5720 m a.s.l.), Mt. Geladaindong (the source region of Yangtze River), in November, 2005. By using a significant positive relationship between ice core δ~(18)O record and summer air temperature (July to September) from the nearby meteorological stations, a history of summer air temperature has been reconstructed for the last 70 years. Summer temperature was relatively low in 1940s and high in 1950s to the middle of 1960s. The lowest temperature occurred in the middle of 1970s. Temperature was low in 1980s and dramatically increased since 1990s, keeping the trend to the begin-ning of the 21st century. The warming rate recorded in the ice core with 0.5℃/10 a since 1970s is much higher that that in the central TP and the Northern Hemisphere (NH), and it becomes 1.1℃/10 a since 1990s which is also higher than these from the central TP and the NH, reflecting an accelerated warm-ing and a more sensitive response to global warming in the high elevation region.     

Phylogenetic relationships of native and introduced Bemisia tabaci (Homoptera:Aleyrodidae) from China and India based on mtCOI DNA sequencing and host plant comparisons

Phylogenetic relationships for Bemisia tabaci were reconstructed by analysis of a ～780 bp fragment of the mitochondrial cytochrome oxidase I (mtCOI) gene with an emphasis on geographic range and distribution among eight eudicot plant families that are common hosts of B. tabaci worldwide to elucidate key phylogeographic linkages between populations extant in China (n=31) and India (n=34). Bootstrap values for the Maximum Parsimony tree were highly robust for all major nodes involving the major Asian clade, subgroups, and sister groups within, at 92%—100%. Between-clade distances for the Southeast Asia and three other major clades, e.g. from sub-Sahara Africa, North Africa-Mediterranean, and the Americas, were approximately >16% divergent. Two major Asian subgroups (I, II) were resolved, which represented populations indigenous to the region, comprising two (I a, I b) and five (II a—e) sister groups, respectively, which diverged by 11%. Two distinct populations from sunflower in Hyderabad grouped separately within the two Asian subgroups. All other populations grouped uniquely within Asian subgroup II or I. The “B” biotype was identified in 23 collections from China at 97.3%—99.5% nucleotide identity with “B” biotype reference sequences; it was not identified in collections from India. The majority of haplotypes were associated with 3—4 plant families, with one exception that for sister group IId (sesame, India), it might be monophagous. Thus, B. tabaci from the southeastern and near eastern regions of the Asian continent comprise of a large number of ancestral, richly divergent, mostly polyphagous populations. This region is therefore hypothesized to constitute an important Old World center of diversification for the B. tabaci complex, together with sub-Saharan Africa.     

太原旅游区位特点及气候因素分析

太原是一座具有2500年历史的古城，历史文化遗产众多，旅游资源丰富，但许多旅游资源还没有转化为旅游产品。太原市的旅游发展具有特殊的区位优势，主要表现在：可开发的客源市场充足；基础设施和环境条件日臻完善；地处山西省疆土的中央，以太原为中心2h-3h路程的“大太原”旅游格局逐渐形成，太原又位于北京与西安两大国际旅游城市连接线的中点，形成北京-山西-陕西旅游黄金通道，太原气候条件优越，文章利用温湿指数和风效指数计算分析了太原全年旅游气候舒适度，得到结论：可以开展旅游的天数可达270d，适宜旅游天数210d，适宜于旅游、休闲、渡假、疗养天数为180d。     

浅析伊通河地表水中镉迁移转化的规律

通过近4a对伊通河长春段6个地表水监测断面中重金属镉的研究，结果表明，地表水中镉的含量随流程的增加而增加，年平均含量也在递增。此外，研究区域内，镉以Cd^2＋为主，且镉有接近超标并逐年升高的趋势。     

Fe(Pd)P合金颗粒的合成及其影响因素

用化学还原法合成了Fe(Pd)P合金颗粒,详细考察了反应温度、溶液的pH值、添加剂、反应物料比以及引发剂等因素对反应速度、产率以及磷含量的影响,选择了适宜的合成条件.