隧洞掘进机(TBM)的洞外组装

概述了隧洞掘进机(TBM)的洞外组装,包括开敞式TBM的设备组成、组装前的准备工作、组装程序及关键性的技术措施。由于场地、机具、材料、人员和技术准备充分,TBM的洞外组装十分顺利。辽宁省水利水电工程局组织国内焊工,将国外焊接技术转化为国内严寒地区的焊接技术,成功地进行了刀盘焊接,基本实现了刀盘焊接的国产化,并在国内首次采用方便快捷的TBM滚轮(Dolly)步进技术。     

考虑形位误差的装配尺寸链计算探讨

通过计算光滑圆柱体的配合间隙,分析了形位公差对加工装配精度的影响,给出包括形位公差在内的有关装配尺寸链的解法,并得出考虑形位误差在内孔轴配合间隙变大的结论。     

Packaged organic materials as monitoring tools for radionuclides

Pint-size perforated polyethylene bags were used as containers to test preserved tea, spinach, ion-exchange resin, live filamentous green algae, and dead filamentous green algae for the sorption and concentration of radionuclides from natural aquatic habitats and from a variety of laboratory controlled nutrient media. These packaged materials have been used to detect trace levels of radionuclides not found by the usual methods of analysis of the raw water itself for dissolved radionuclides.     

具有形位误差的装配尺寸链的分析计算

研究了形位误差对装配精度的影响，通过分析把形位误差作为一个减环纳入装配尺寸链内，并用表格法进行计算，保证了装配尺寸链的计算精度，为进一步提高机械产品质量提供了理论依据。     

Double perovskites as anode materials for solid-oxide fuel cells

Extensive efforts to develop a solid-oxide fuel cell for transportation, the bottoming cycle of a power plant, and distributed generation of electric energy are motivated by a need for greater fuel efficiency and reduced air pollution. Barriers to the introduction of hydrogen as the fuel have stimulated interest in developing an anode material that can be used with natural gas under operating temperatures 650 degrees C < T < 1000 degrees C. Here we report identification of the double perovskites Sr2Mg(1-x)MnxMoO(6-delta) that meet the requirements for long-term stability with tolerance to sulfur and show a superior single-cell performance in hydrogen and methane.     

Plant crops as a source of fuel and hydrocarbon-like materials

Chemical analyses have been made of a number of plant species in order to assess their suitability as renewable sources of hydrocarbon-like photosynthetic products. Yields of rubber and wax, glycerides, isoprenoids, and other terpenoids were estimated. Individual sterols were identified in latex from some species.     

Mitochondrial DNA as a genomic jigsaw puzzle

In mitochondria of the unicellular eukaryote Diplonema, genes are systematically fragmented into small pieces that are encoded on separate chromosomes, transcribed individually, and then concatenated into contiguous messenger RNA molecules.     

Reaction of the antitumor antibiotic CC-1065 with DNA: structure of a DNA adduct with DNA sequence specificity

Sequence-dependent variations in DNA revealed by x-ray crystallographic studies have suggested that certain DNA-reactive drugs may react preferentially with defined sequences in DNA. Drugs that wind around the helix and reside within one of the grooves of DNA have perhaps the greatest chance of recognizing sequence-dependent features of DNA. The antitumor antibiotic CC-1065 covalently binds through N-3 of adenine and resides within the minor groove of DNA. This drug overlaps with five base pairs for which a high sequence specificity exists.     

Mutant of Bacterium paracoli 5099 with an altered DNA: identification as a Flavobacterium

A difference in the base composition of the DNA of Bacterium paracoli 5099 and of a "mutant" (No. 1975) derived from it was found. This is in accordance with the finding of others. However, biochemical tests revealed that the "mutant" was a Flavobacterium, whereas the parent strain belonged to a species of Escherichia. The base composition of the DNA of the "mutant" is similar to that reported for the DNA of Flavobacterium.     

微卫星DNA标记技术及其应用

微卫星DNA是高等真核生物基因组中种类多、分布广、具有高度的多态性和杂合度的分子标记,由于其具有多态性检出率高、信息含量大、共显性标记、实验操作简单、结果稳定可靠等优点,已经成为种群遗传学研究中被广泛应用的分子遗传标记．微卫星DNA标记技术在动物亲缘关系的鉴定、特定基因定位、群体遗传结构的分析、物种的进化和系统发生以及遗传基因连锁图谱的构建等方面已得到了广泛的应用．因此,就微卫星DNA遗传标记的原理、特点及应用等方面进行综述。     

土壤微生物总DNA的V_3可变区PCR反应体系优化

为了优化以土壤微生物DNA为模板的PCR反应条件,采用E.Z.N.A.soil DNA kit试剂盒提取土壤微生物总DNA,对16SrDNA V3可变区的PCR反应体系和反应条件进行优化。主要从DNA模板用量、引物浓度、退火温度、热启动方式4个方面进行筛选试验,最后得出最适宜的土壤DNA扩增体系为:10.5ng模板DNA、5μL 10×buffer、4μL 2.5mmol/L dNTP、10μmol/L引物各1.5μL,2.5UTaq酶,加无菌ddH2O补足至50μL;PCR循环程序为:94℃预变性5min;94℃变性1min,52℃退火1min,72℃延伸70s,29个循环;72℃延伸5min。试验结果表明:选择热启动方式和合适的退火温度是获得高质量PCR产物的关键。     

ITS序列作为DNA条形码在虫草鉴定及系统发育关系中的研究与应用

冬虫夏草具有重要的药用价值,随着天然虫草资源的日益紧张,急需开发虫草尤其是冬虫夏草资源,首要任务便是准确快速地鉴别虫草及无性型菌种、确认虫草的系统发育地位及与其他种属的亲缘关系。由于虫草复性生活史复杂,运用传统的分类学方法并不能很好地对它进行鉴定[1]。DNA指纹技术为探讨真菌的系统发育及其进化地位提供了新的途径,近年来已成为分类研究领域的热点[2]。它是通     

Actinide topological insulator materials with strong interaction

Topological band insulators have recently been discovered in spin-orbit coupled two-and three-dimensional systems. We theoretically predict a class of topological insulators where interaction effects play a dominant role. In actinide elements, simple rocksalt compounds formed by Pu and Am lie on the boundary between metals and insulators. We show that interaction drives a quantum phase transition to a topological insulator phase with a single Dirac cone on the surface. These putative topological insulators may provide a setting for both applied and fundamental investigation.     

外源DNA直接导入玉米的分子育种技术研究初报

用玉米作为受体,以水稻、甘蔗、象草、竹子等亲缘较远的植物DNA作为供体,用花粉管通道法、种子萌动浸渍法、受体花粉携带法、未成熟籽粒微注射法将供体DNA直接导入受体.发现玉米D1代在质量性状和数量性状都产生变异,而其中以花粉管通道法效果最好,种子萌动浸渍法次之,注射法最差.     

特殊润湿性油水分离材料的研究进展

近几年,石油和有机化学品泄漏对人们的生存环境乃至生态系统造成了极为严重的损害。油水分离手段及其材料的研发已成为一个全球性的,需要众人为之努力的重要任务。受到大自然的启发,许多具有特殊润湿性的材料得以合成与发展,尤其是超疏水—超亲油、超亲水—超疏油材料已成功用于选择性油水分离,并显示出诱人的应用前景。这篇文章简要介绍了自然界的特殊浸润现象以及微—纳多级结构的制备方法;综述了以金属网、海绵、无机粉体为基材的新型油水分离材料;提出了该特殊材料存在的问题与拟解决办法;重点介绍并总结了以生物质材料如木粉、秸秆粉、滤纸、棉花、棉织物等作为基材,合成特殊润湿性油水分离生物质材料的优势与发展现状,并对该领域的研究趋势进行了展望。