综采面扇形开采工艺技术应用

本文章详细描述了7305综采工作面在回采过程中为防止运输机下滑所采取的设备布置和扇形开采工艺,并提出了运输机在工作面推进过程中的技术指导和现场控制应用,对不规则工作面布置的生产管理有一定的借鉴作用。     

Fluidic Control System Employing Micropump and Microvalves for Cell Isolation

IntroductionMany chip- based devices ( e.g.,micropumps[17]and microvalves[815] ) have been developed afternumerous efforts in the past decades.Developments in microfabrication technology havegreatly accelerated the progress towards a micrototal analysis system (μTAS ) in whichmicrofluidics plays a significant role includingreagent mixing,sample isolation,and the controlof fluidic flow rate and direction. The fluidiccontrol system described in this paper uses aminiaturized off- chip micropump…     

拍现象及其影响因素的可视化分析

拍现象是一种由两个简谐振动合成产生的幅值随时间周期性变化的现象。从拍现象及其特征出发，分析拍产生的条件，并借助计算机绘图从圆频率、相位、幅度三个方面讨论影响拍的因素，为深刻理解拍现象提供了很好的可视化手段。     

关于解决农村饮水安全问题的思考

指出了农村存在的饮水安全问题,分析了农村水污染严重,水环境恶化的原因,提出了解决措施.     

Temperature Control System for Biochemical Reactions in Microchip-Based Devices

IntroductionIn recent years,the development of miniaturizedsystems for chemical and biochemical reactions hasrapidly progressed[1] .Most of the microdevices forconducting these reactions are made of silicon orglass using conventional microfabrication methodsused in the microelectronic industry or bymodifying the processing technologies for microelectromechanical systems ( MEMS) . Severalresearch groups have developed polymerase chainreactions ( PCR) chips with various features toperform sim…     

松扁叶蜂的生物学与防治对策

松扁叶蜂(Acantholyda posticalis Matsumura)属膜翅目,扁叶蜂科。1981年在河南省三门峡市首次发现,1984年后在该地区成灾。此虫一年发生1代,5月下旬幼虫孵出,进入为害期,为害时间35-40天,以老熟幼虫越冬越夏。本文还报道了松扁叶蜂的生活习性,并提出了防治对策。     

Insights from the genome of the biotrophic fungal plant pathogen Ustilago maydis

Ustilago maydis is a ubiquitous pathogen of maize and a well-established model organism for the study of plant-microbe interactions. This basidiomycete fungus does not use aggressive virulence strategies to kill its host. U. maydis belongs to the group of biotrophic parasites (the smuts) that depend on living tissue for proliferation and development. Here we report the genome sequence for a member of this economically important group of biotrophic fungi. The 20.5-million-base U. maydis genome assembly contains 6,902 predicted protein-encoding genes and lacks pathogenicity signatures found in the genomes of aggressive pathogenic fungi, for example a battery of cell-wall-degrading enzymes. However, we detected unexpected genomic features responsible for the pathogenicity of this organism. Specifically, we found 12 clusters of genes encoding small secreted proteins with unknown function. A significant fraction of these genes exists in small gene families. Expression analysis showed that most of the genes contained in these clusters are regulated together and induced in infected tissue. Deletion of individual clusters altered the virulence of U. maydis in five cases, ranging from a complete lack of symptoms to hypervirulence. Despite years of research into the mechanism of pathogenicity in U. maydis, no 'true' virulence factors had been previously identified. Thus, the discovery of the secreted protein gene clusters and the functional demonstration of their decisive role in the infection process illuminate previously unknown mechanisms of pathogenicity operating in biotrophic fungi. Genomic analysis is, similarly, likely to open up new avenues for the discovery of virulence determinants in other pathogens.     

Global trends of whole-genome duplications revealed by the ciliate Paramecium tetraurelia

The duplication of entire genomes has long been recognized as having great potential for evolutionary novelties, but the mechanisms underlying their resolution through gene loss are poorly understood. Here we show that in the unicellular eukaryote Paramecium tetraurelia, a ciliate, most of the nearly 40,000 genes arose through at least three successive whole-genome duplications. Phylogenetic analysis indicates that the most recent duplication coincides with an explosion of speciation events that gave rise to the P. aurelia complex of 15 sibling species. We observed that gene loss occurs over a long timescale, not as an initial massive event. Genes from the same metabolic pathway or protein complex have common patterns of gene loss, and highly expressed genes are over-retained after all duplications. The conclusion of this analysis is that many genes are maintained after whole-genome duplication not because of functional innovation but because of gene dosage constraints.     

Analysis of one million base pairs of Neanderthal DNA

Neanderthals are the extinct hominid group most closely related to contemporary humans, so their genome offers a unique opportunity to identify genetic changes specific to anatomically fully modern humans. We have identified a 38,000-year-old Neanderthal fossil that is exceptionally free of contamination from modern human DNA. Direct high-throughput sequencing of a DNA extract from this fossil has thus far yielded over one million base pairs of hominoid nuclear DNA sequences. Comparison with the human and chimpanzee genomes reveals that modern human and Neanderthal DNA sequences diverged on average about 500,000 years ago. Existing technology and fossil resources are now sufficient to initiate a Neanderthal genome-sequencing effort.