振动力场作用下高分子熔体表观粘度的计算

不依赖现有的本构关系，推导出了平行叠加振动条件下高分子熔体表现粘度的计算公式．建立了在自行研制的恒速型毛细管动态流变装置上计算高分子熔体表观粘度的步骤和方法．以低密度聚乙烯(LDPE)为原材料，实验测量一定振动频率和振幅下毛细管入口压力、活塞杆振动位移、入口压力与振动位移相位差的瞬态值，即可求得毛细管壁处LDPE熔体的表观粘度．     

自然科学领域著名期刊简介——Nature及其姊妹刊

Nature杂志发行 13 5年来一直是科学研究领域最具影响力的媒介之一 ,其 8种姊妹月刊和 7种综述性期刊也是科学研究成果报道的前沿阵地。本文旨在介绍Nature及其姊妹刊的办刊宗旨、征稿要求及评议程序 ,以期使大家更好地了解Nature系列期刊 ,提高投稿率和录用率 ,把我们出色的科研成果展示给世界 ;并希望通过阅读Nature系列期刊 ,把握最前沿的科研动态 ,加强我国科学家与世界科学界的联系     

基于层次分析法和集对理论的硫化矿自燃倾向性评定

采用多因素综合鉴定法对某硫铁矿的9个矿样进行了实验室自燃倾向性鉴定,得到了矿样的化学成分分析结果,矿相分析结果,矿样中水溶性铁离子、硫酸根离子含量随氧化时间的变化规律结果,自热性指标、自燃性指标。建立了硫化矿自燃倾向性判定流程的结构图,根据确定的硫化矿石倾向性分级标准,利用AHP方法和集对分析理论确定了该矿9个矿样的同一度和对立度,并进一步分析评价了指标数值与自燃倾向性分级标准之间的数量关系,得到了9个矿样的平均联系度;根据联系度的同异反态势确定联系度所属的集对态势,最后根据集对态势得到了9个矿样的氧化程度及自燃倾向性程度分级,得到了定量化的安全评价结果。该研究方法对硫化矿石自燃的安全评价具有指导意义。     

Identification and characterization of CACTA transposable elements capturing gene fragments in maize

Transposable elements (TEs)-mediated gene sequence movement is thought to play an important role in genome expansion and origin of genes with novel functions. In this study, a gene, HGGT, involved in vitamin E synthesis was used in a case study to discover and characterize transposons carrying gene fragments in maize. A total of 69 transposons that are distributed across the 10 chromosomes and have an average length of 3689 bp were identified from the maize sequence database by using the BLAST search algori...     

Characterizations of Phosphorus - containing Flame - retardant Poly (Ethylene Terephthalate) Copolyester

Copolyesters of phosphorus - containing flame - retardant poly(Ethylene Terephthalate) (PET) have been prepared and characterized with the objection of producing an effective, environmentally friendly, nonfugitive alternatives to halogen flame retardant system for practical application. With means of NMR, DSC, DTA/TGA, SEM and LOI, structure, thermal property and flam-mability are investigated which reveal that the flame -retardant PET when copolymerized with 2 - carboxyethyl (phenylphosphinic) acid (CEPP) confers excellent fire retardancy with LOI > 28, broader thermal degradation temperature and increased char formation.     

Room temperature ferromagnetism of Ni,(Ni,Li),(Ni,N)-doped ZnO thin films

Ni-doped ZnO thin films (Ni concentration up to 10 mol%) were generated on Si (100) substrates by a sol-gel technique. The films showed wurtzite structure and no other phase was found. The chemical state of Ni was found to be bivalent by X-ray photoelectron spectroscopy. The results of magnetic measurements at room temperature indicated that the films were ferromagnetic, and magnetic moment decreased with rise of Ni concentration. The magnetization of Ni (10 mol%)-doped ZnO film annealed in nitrogen was low...     

Genome-wide association study identifies a common variant associated with risk of endometrial cancer

Endometrial cancer is the most common malignancy of the female genital tract in developed countries. To identify genetic variants associated with endometrial cancer risk, we performed a genome-wide association study involving 1,265 individuals with endometrial cancer (cases) from Australia and the UK and 5,190 controls from the Wellcome Trust Case Control Consortium. We compared genotype frequencies in cases and controls for 519,655 SNPs. Forty seven SNPs that showed evidence of association with endometrial cancer in stage 1 were genotyped in 3,957 additional cases and 6,886 controls. We identified an endometrial cancer susceptibility locus close to HNF1B at 17q12 (rs4430796, P = 7.1 × 10(-10)) that is also associated with risk of prostate cancer and is inversely associated with risk of type 2 diabetes.     

线性不确定系统的约束鲁棒采样控制

针对连续系统直接设计数字控制器的采样控制理论引起了广泛的重视．目前采样控制理论不易处理系统的参数不确定性和状态的时域约束,基于实用稳定性理论给出了采样系统实用稳定的条件,在此基础上分析了线性参数不确定系统的采样控制问题,结果表示为线性矩阵不等式．提出的方法弥补了传统采样控制方法在处理系统的不确定性和时域性能约束上的不足,因此结果具有较大的理论与应用价值     

具有软起动、软停止功能的微机控制起动器

分析了软起动、软停止交流起动器的工作原理,给出了软起动、软停止起动器的设计思路.     

不结球白菜SSR引物的高效开发及其通用性研究

利用改进的ISSR-PCR分离不结球白菜基因组微卫星,进行两步PCR,分别设计出SSR两端引物IP2和IP3（即SSR引物对）,SSR引物产率为12%,明显高于传统方法.不结球白菜SSR序列以（GA）n为主,占70%.将69对SSR引物用于芸苔属其它8种作物的扩增,97%引物有显著扩增,扩增率最高的为四倍体白菜和甘蓝（85.5%）,最低的为青花菜（49.3%）.10对为通用引物,在所检测的8种作物中片段大小一致,其余的扩增片段和数目差异较大,表现出较为丰富的多态性.尤其是在C基因组的甘蓝和花椰菜上,最多可检测到5个位点,表明运用lSSR-PCR开发出的引物多态性较高.