Significance of the length of the shortest tree

The distribution of lengths of phylogenetic trees under the taxonomic principle of parsimony is compared with the distribution obtained by randomizing the characters of the sequence data. This comparison allows us to define a measure of the extent to which sequence data contain significant hierarchical information. We show how to calculate this measure exactly for up to 10 taxa, and provide a good approximation for larger sets of taxa. The measure is applied to test sequences on 10 and 15 taxa.     

汉语广告英译中修辞手法的应用

广告讲究修辞技巧，广告英译时适当使用修辞手段能够体现广告的特点。从重复、头尾韵、隐喻、拟人、对比、排比、对偶、双关、套用或更改惯用句式等方面探讨了如何使用修辞手段翻译汉语广告。     

Apolipoprotein-mediated pathways of lipid antigen presentation

Peptide antigens are presented to T cells by major histocompatibility complex (MHC) molecules, with endogenous peptides presented by MHC class I and exogenous peptides presented by MHC class II. In contrast to the MHC system, CD1 molecules bind lipid antigens that are presented at the antigen-presenting cell (APC) surface to lipid antigen-reactive T cells. Because CD1 molecules survey endocytic compartments, it is self-evident that they encounter antigens from extracellular sources. However, the mechanisms of exogenous lipid antigen delivery to CD1-antigen-loading compartments are not known. Serum apolipoproteins are mediators of extracellular lipid transport for metabolic needs. Here we define the pathways mediating markedly efficient exogenous lipid antigen delivery by apolipoproteins to achieve T-cell activation. Apolipoprotein E binds lipid antigens and delivers them by receptor-mediated uptake into endosomal compartments containing CD1 in APCs. Apolipoprotein E mediates the presentation of serum-borne lipid antigens and can be secreted by APCs as a mechanism to survey the local environment to capture antigens or to transfer microbial lipids from infected cells to bystander APCs. Thus, the immune system has co-opted a component of lipid metabolism to develop immunological responses to lipid antigens.     

岗位工资制--企业内部分配改革的方向

岗位工资制是一种具有较强激励作用的新型的基本工资制度，按照建立现代企业制度的要求，并根据人力资源的特点，企业应结合实际，制订出既符合国家政策，又能最大限度地调动员工积极性的分配模式。     

CSP工艺生产低碳钢中的纳米碳化物及其对钢的强化作用

用化学相分析及X射线小角散射法研究了CSP工艺生产HSLC钢中碳化物的成分、数量及粒度分布，发现尺寸小于18nm的碳化物含量大于文献中测定的CSP含Nb的HSLA钢中尺寸小于18nm的Nb(CxNy)含量。对纳米级碳化物对钢的强化作用进行了讨论。     

热轧全波纹腹板H型钢矫直的实验研究

为解决热轧波纹腹板Ｈ型钢的矫直．通过大量实验，提出了压矫腹板带动翼缘弯曲变形的矫直方法．实验结果表明该方法是可行的．     

Chromosome-wide SNPs reveal an ancient origin for Plasmodium falciparum

The Malaria's Eve hypothesis, proposing a severe recent population bottleneck (about 3,000-5,000 years ago) of the human malaria parasite Plasmodium falciparum, has prompted a debate about the origin and evolution of the parasite. The hypothesis implies that the parasite population is relatively homogeneous, favouring malaria control measures. Other studies, however, suggested an ancient origin and large effective population size. To test the hypothesis, we analysed single nucleotide polymorphisms (SNPs) from 204 genes on chromosome 3 of P. falciparum. We have identified 403 polymorphic sites, including 238 SNPs and 165 microsatellites, from five parasite clones, establishing chromosome-wide haplotypes and a dense map with one polymorphic marker per approximately 2.3 kilobases. On the basis of synonymous SNPs and non-coding SNPs, we estimate the time to the most recent common ancestor to be approximately 100,000-180,000 years, significantly older than the proposed bottleneck. Our estimated divergence time coincides approximately with the start of human population expansion, and is consistent with a genetically complex organism able to evade host immunity and other antimalarial efforts.     

基于信息共享的上海铁路集装箱多式联运中心

提出了组建上海铁路集装箱多式联运中心 ,建成铁路国际集装箱运输信息交换系统 .以运输信息为资源 ,提高运输效率 ,促进集装箱多式联运 ,最终达到运输经济增长的效果 .     

O'-Sialon/BN和O'-Sialon/ZrO2复合材料抗熔融金属和保护渣侵蚀

研究了O′－Sialon/BN和O′－Sialon/ZrO2复合材料抗溶融金属和保护渣侵蚀,结果表明：O′－Sialon/BN复合材料抗钢水侵蚀的动力学分为两段控制：前期为界面化学反应控制,后期为扩散控制,O′－Sialon/ZrO2复合材料具有良好的保护渣侵蚀性能,这是由于ZrO2在硅酸盐溶体中的溶解度较低,随着ZrO2的增加,抑制了O′－Sialon与CO,以及渣中其他组元的反应,从而提高了O′－Sialon抗的侵蚀性。