变更图的边添加

证明了:对任何整数t≥6和d≥2,从一条长为d的简单路通过添加t条边后得到的图的最小直径上界为[d-2/t 1] 2,如果d∈J'(t,k)={2k(t 1) 1,2k(t 1) 2,2k(t 1)-t 1}∪{2k(t 1)-t h:h=6,7,…,t};其他情形为[d-2/t 1] 1.这个证明改进了已知结果,而且[d-2/t 1] 1是最好的上界.     

嗜盐菌的研究新进展

嗜盐菌作为一种新型微生物资源,已经在很多方面得到应用.如：为微生物生理、分类,系统发育学和生命科学研究提供新的课题,因此,嗜盐菌已引起人们的广泛关注.文章主要讨论了嗜盐菌的嗜盐机理和应用方面的研究新进展.     

The fate of injectant coal in blast furnaces: The origin of extractable materials of high molecular mass in blast furnace carryover dusts

The aim of the work was to investigate the fate of injectant coal in blast furnaces and the origin of extractable materials in blast furnace carryover dusts. Two sets of samples including injectant coal and the corresponding carryover dusts from a full sized blast furnace and a pilot scale rig have been examined. The samples were extracted using 1-methyl-2-pyrrolidinone (NMP) solvent and the extracts studied by size exclusion chromatography (SEC). The blast furnace carryover dust extracts contained high molecular weight carbonaceous material, of apparent mass corresponding to 10⁷?10⁸ u, by polystyrene calibration. In contrast, the feed coke and char prepared in a wire mesh reactor under high temperature conditions did not give any extractable material. Meanwhile, controlled combustion experiments in a high-pressure wire mesh reactor suggest that the extent of combustion of injectant coal in the blast furnace tuyeres and raceways is limited by time of exposure and very low oxygen concentration. It is thus likely that the extractable, soot-like material in the blast furnace dust originated in tars is released by the injectant coal. Our results suggest that the unburned tars were thermally altered during the upward path within the furnace, giving rise to the formation of heavy molecular weight (soot-like) materials.     

基于双Wollaston棱镜偏振干涉成像光谱仪的光通量分析

光通量是振干涉成像光谱仪的关键参量之一。该文在非理想情况下，通过分析Wollaston分束器和检偏器对入射光强的削弱作用，对基于双Wollaston棱镜的偏振干涉成像光谱仪的光通量进行了讨论，得到了较精确的光通量表达式，给出了最大调制度下的通量数值，并与近似理想条件下的光通量进行了比较。     

甘肃西部马鬃山超镁铁质杂岩岩石学地球化学信息及意义

马鬃山岩体在空间上分为有成因联系的两部分，主岩体为具有环状分异特征的辉长岩岩体，中心相为辉长岩，边缘相为闪长岩．主岩体东南子岩体为橄榄二辉岩岩体．赋存于其中的岩石学和地球化学信息暗示马鬃山杂岩体形成于活动大陆边缘张裂构造环境，为应力释放期的产物，岩浆来源于具有E—MORB性质的陆下岩石圈地幔与软流圈的边界。较大程度部分熔融产生的岩浆在上升途中同化了陆壳围岩。     

^210Pbex depth distribution in soil and calibration models for assessment of soil erosion rates from ^210Pbex measurements

Throughout the past decade, the potential for using nuclear weapon-produced 137Cs ( half-life 30.2 a) fallout to quantify soil erosion rates on both cultivated and uncul- tivated lands for medium-term timescales (≈ 40 a) has been successfully demonstrated in a wide range of envi- ronments in different regions of the world[1—6]. Because in difficulties of distinguishing Chernobyl-derived compo- nent from total 137Cs input in many parts of Europe, and in measuring low activity samples of…     

Temperature variations on the Tibetan Plateau over the last two millennia

The paleoclimate data recovered from ice cores,tree rings and lake sediments indicate regional features of cfimatic change on the Tibeta n Plateau (TP) during the last 2000 years. The composite temperature reconstructions in-dicate that several main climatic episodes, such as the “LittleIce Age“ between 1400 and 1900, the “Medieval Warm Pe-riod“ in 1150-1400, a less warm period in 800-1100, and an earlier cold period between the 3rd and 5th centuries,occurred in the TP. In addition, temperature varied from region to region. The period from AD 800 to 1100, which waswarm in northeastern TP, was contemporaneous with cool-ing in the western and southern TP. The southern TP ex-perienced warming between 1150 and 1400. For western TP,the δ^18O records of the Guliya ice core indicate that the pe-Hod 1250-1500 witnessed a clear warming. Large-scaletrends in the temperature history from northeastern TP aremore similar to those in eastern China than are the trendsfrom the Guliya ice cap far to the west and southern TP. The most prominent similarities between the temperature varia-tions of the TP and eastern China are such cold phases as 1100-1150, 1500-1550, 1650-1700 and 1800-1850, andthe latter three cold events match with three widespreadg lacial advances which occurred on the TP during the Little Ice A2e.     

A carbon- and oxygen-isotope record of recent environ- mental change from Qinghai Lake, NE Tibetan Plateau

An understanding of natural climatic variability is essential for evaluating anthropogenic impacts on recent and future climate[1—3]. Due to the lack of lengthy instrumental records, such an understanding must be gained from natural archives of climate change. Palaeolimnological indicators of past lake levels may provide a sensitive record of changes in effective precipitation in closed basins. This approach is particularly relevant on the Tibetan Plateau, where instrumental records are very…     

卷积积分的几种方法

卷积积分是信号与线性系统课程中的重要运算工具。本介绍卷积积分的图解法和性质法以外，又讨论了卷积积分的定义法和数值计算法。     

渭干河-库车河绿洲生态环境变化特征与防治对策

近50年来，渭干河-库车河三角洲绿洲地区在人类不合理活动的作用下，水与生态环境发生了一系列变化。因此,进行水资源统筹利用规划与管理，统筹兼顾各县的经济发展与生态环境建设对水的需求，以生态系统健康发展为原则，遵循生态规律来进行土地资源的开发利用，开展整个绿洲为单元的生态功能保护与建设是绿洲可持续发展能力的根本途径。