X-ray Pulsar in the Crab Nebula

X-ray pulsations have been observed in the Crab Nebula at a frequency closely matching the radio and optical pulsations. About 5 percent of the total x-ray power of the nebula appears in the pulsed component. The x-ray pulsations have the form of a main pulse and an interpulse separated by about 12 milliseconds.     

High-Resolution X-ray Observations of the Orion Nebula

Observations of the Trapezium region in the Orion Nebula obtained with the high-resolution x-ray imaging instrument on board the Einstein Observatory reveal at least 58 sources of x-ray emission. All but two of the sources can be identified with visible stars. The strongest x-ray source is the star Theta(1)C, which excites the emission nebula. Its x-ray luminosity is 6 x 10(32) ergs per second. The rest of the x-ray sources may be identified with stars of all spectral types. Strong x-ray emission is not observed from members of the infrared cluster embedded within the Orion molecular cloud.     

ROSAT X-ray detection of a young brown dwarf in the chamaeleon I dark cloud

Photometry and spectroscopy of the object Cha Halpha 1, located in the Chamaeleon I star-forming cloud, show that it is a approximately 10(6)-year-old brown dwarf with spectral type M7.5 to M8 and 0.04 +/- 0.01 solar masses. Quiescent x-ray emission was detected in a 36-kilosecond observation with 31.4 +/- 7.7 x-ray photons, obtained with the Rontgen Satellite (ROSAT), with 9final sigma detection significance. This corresponds to an x-ray luminosity of 2.57 x 10(28) ergs per second and an x-ray to bolometric luminosity ratio of 10(-3.44). These are typical values for late M-type stars. Because the interior of brown dwarfs may be similar to that of convective late-type stars, which are well-known x-ray sources, x-ray emission from brown dwarfs may indicate magnetic activity.     

A Lunar Occultation of the Dust-Scattering Halo Around GX 5-1 Observed with ROSAT

The x-ray source GX 5-1 in the galactic bulge has been observed with the position-sensitive proportional counter onboard the R?ntgen satellite (ROSAT) during and after a lunar occultation. Extended emission around the source was unambiguously discovered while the central source was behind the lunar rim. This emission is interpreted as a dust-scattering halo around GX 5-1 that has a fractional intensity of 28 percent, implying a grain column density between GX 5-1 and Earth of approximately 3 x 10(10) per square centimeter. The halo derived from imaging during the ROSAT all-sky survey is identical to that obtained from the lunar occultation, thus demonstrating that the ROSAT x-ray mirror scattering has not changed as compared with the mirror properties as measured in preflight calibrations.     

X-ray Detection of the Period-Four Cycling of the Manganese Cluster in Photosynthetic Water Oxidizing Enzyme

X-ray absorption near-edge structure spectra of the manganese (Mn) cluster in physiologically native intermediate states of photosynthetic water oxidation induced by short laser flash were measured with a compact heat-insulated chamber equipped with an x-ray detector near the sample surface. The half-height energy of the Mn Kedge showed a period-four oscillation dependent on cycling of the Joliot-Kok's oxygen clock. The flash number-dependent shift in the Mn K-edge suggests that the Mn cluster is oxidized by one electron upon the S(0)-to-S(1), S(1)-to-S(2), and S(2)-to-S(3) transitions and then reduced upon the S(3)-to-S(0) transition that releases molecular oxygen.     

谈影子价格在企业经营管理中的应用

介绍了影子价格理论在我国的发展过程、影子价格的概念及含义。结合具体实例阐述了如何运用影子价格理论指导企业经营管理。从而提高企业的经济效益．     

牛冠状病毒4H12/1D4单链基因片段在大肠杆菌中的表达

用ＥｃｏＲＩ酶切ＰＲ５Ｂ４质粒，采用“Ｖ”字形内槽电洗脱法回收约０．８０４Ｋｂ牛冠状病毒基因工程抗体４Ｈ１２／１Ｄ４单链基因片段，并将其插入载体质粒ＰＥＴ－１７ｂ的ＥｃｏＲＩ位点构成重组质粒ＰＥＴ－Ｄ４，将重组质粒转化ＤＨ５α感受态细胞，在ＩＰＴＧ的诱导下表达，细菌裂解物经ＳＤＳ－ＰＡＧＥ电泳筛选，发现含ＰＥＴ－Ｄ４细菌经诱导新增一条约２８ＫＤα蛋白带，该蛋白带与设计基因工程抗体的大小相符，经光密度扫描，表达量约占菌体总蛋白的１４％     

探析自然光影在园林景观中的艺术表达

光影是园林景观中重要的设计元素,园林中光与影的平衡可以使景致更加丰富自然。分析了自然光影与造园要素——建筑、水景、植物、小品等的艺术关系,探究了光影在创建园林空间中的作用和艺术表现,以此强调光影在园林景观中的重要价值。     

55份小麦品种（系）抗条锈病基因和1BL／1RS易位的分子检测

通过已报道的Yr5、Yr10和1BL/1RS分子标记,对55份供试小麦品种(系)进行分子检测.结果表明:供试材料中均不含抗条锈病基因Yr5;有2份含抗条锈病基因Yr10;含1BL/1RS的易位材料比例较高,占25.5%.为抵抗当前流行的条锈病病菌生理小种,小麦育种应加强抗病基因Yr5和Yr10的应用.鉴于1BL/1RS易位对面包品质的不利影响,在亲本利用上应更加谨慎.     

光影艺术在现代景观设计中的应用研究

光影作为一种艺术手段,一直以来被广泛应用在摄影、绘画、建筑设计以及室内设计中,而在现代景观设计中的应用缺乏关注。光影艺术的应用研究无疑对当代景观设计师在空间塑造、融合室内外景观和营造意境等方面有很好的启发意义。笔者着重从光影的艺术表现、功能作用及其营造方法三方面来探讨光影在现代园林景观设计中的作用及意义。     

H1N1亚型猪流感诊断方法的研究新进展

2009年,甲型H1N1流感在全球多个地方猪和人群中暴发,给人民群众的生命健康带来了巨大威胁,给经济发展和社会稳定产生了严重影响.及时快速的诊断是有效控制疫情大规模暴发的最有效途径之一.近几年随着现代分子生物学技术发展,猪流感诊断方法在快速、准确性方面有了很大提高.对H1N1猪流感概况及猪流感的诊断方法进行了综述.     

HPLC-ESI-MS/MS检测蜂蜜中林可霉素残留

[目的]建立蜂蜜中林可霉素残留的高效液相色谱-电喷雾串联质谱(HPLC-ESI-MS/MS)检测方法。[方法]样品经固相萃取净化、液相色谱分离后进行质谱分析,在多反应监测模式(MRM)下进行特征母离子、子离子对信号采集。根据保留时间、母离子和两个特征子离子进行定性分析,以离子峰度最强的基峰离子m/z126进行定量。[结果]在1.0~20.0 ng/ml线性范围内,峰强度与添加浓度的线性关系良好(r2>0.9996)。在2.5、5.01、0.0 ng/g 3个添加水平,林可霉素的平均回收率范围为(95.1±3.3)%,日内测定结果的相对标准偏差小于5.3%,日间测定结果的相对标准偏差小于8.5%,最低检测限0.1 ng/g。[结论]HPLC-ESI-MS/MS用作检测蜂蜜中林可霉素残留的方法,灵敏度高、精密度好,达到了林可霉素残留分析的要求。     

峰谷分时分季上网电价计算模式及应用

在研究制定上网电价的基本原则和方法的基础上，提出了水电厂峰谷分时上网电价和丰枯分季上网电价的计算模式。这种模式，既适用于按财务决算资料来确定分季峰谷上网电价，也适用于按现行电价水平来制定分季峰谷上网电价     

Detection of an Amplasma marginale antibody complex formed in vivo

A naturally occurring anaplasma-antibody complex was detected by exposing erythrocytes of infected cattle to fluorescein-labeled bovine antiglobulin. This technique revealed not only the classical marginal bodies but also the initial Anaplasma bodies in the erythrocytes of acutely infected animals. Singly occurring initial bodies were observed in the erythrocytes of healthy carriers.     

X-ray Structures of the Sun during the Importance 1N Flare of 8 June 1968

High-resolution solar x-ray images were obtained with a rocket-borne grazing incidence telescope. The x-ray flare is large in extent, has fine strulctuire, and follows a neutral magnetic line. X-ray emitting coronal links interconnect active regions. The general coronal emission at the limb and several faint regions on the disc are observed.     

威宁绵羊IGF-1基因外显子多态性分析

为了更好地保护和开发利用威宁绵羊这一优良地方品种,本实验利用威宁绵羊构建DNA池,设计4对引物扩增威宁绵羊IGF-1基因外显子及部分内含子序列。将PCR产物纯化并进行双向测序,通过DNAStar生物软件分析确定多态性位点。利用在线生物信息学软件分析多态位点对IGF-1基因RNA的二级结构、类胰岛素生长因子1的二级和三级结构的影响。结果表明,在扩增的IGF-1基因中筛选到3个SNPs:Intron1-A4387C、Exon2-T87C、Exon4-A27T,其中Exon4-A27T为错义突变,导致编码的精氨酸(Arg)变为丝氨酸(Ser);Exon2-T87C多态位点均未改变氨基酸的编码,为同义突变;Intron1-A4387C在内含子区,不参与氨基酸编码。     

Detection of near-atmospheric concentrations of CO2 by an olfactory subsystem in the mouse

Carbon dioxide (CO2) is an important environmental cue for many organisms but is odorless to humans. It remains unclear whether the mammalian olfactory system can detect CO2 at concentrations around the average atmospheric level (0.038%). We demonstrated the expression of carbonic anhydrase type II (CAII), an enzyme that catabolizes CO2, in a subset of mouse olfactory neurons that express guanylyl cyclase D (GC-D+ neurons) and project axons to necklace glomeruli in the olfactory bulb. Exposure to CO2 activated these GC-D+ neurons, and exposure of a mouse to CO2 activated bulbar neurons associated with necklace glomeruli. Behavioral tests revealed CO2 detection thresholds of approximately 0.066%, and this sensitive CO2 detection required CAII activity. We conclude that mice detect CO2 at near-atmospheric concentrations through the olfactory subsystem of GC-D+ neurons.     

在建设国际旅游岛背景下加快发展海南热带休闲农业的思路与对策

休闲农业是农业和服务业相结合的一种新兴休闲服务产业。海南建设国际旅游岛,加快海南农业现代化步伐,需要加快发展热带休闲农业。本文从海南发展热带休闲农业的必要性与可行性入手,分析制约其发展的诸多因素,提出加快发展海南热带休闲农业的思路与对策。     

LC-MS/MS技术在丙溴磷残留检测中的应用

采用液相色谱-串联质谱(LC-MS/MS)技术对水稻植株、稻田土壤、田水、稻壳以及糙米等样品中的丙溴磷残留进行测定。试验结果表明:丙溴磷的子离子m/z 344.8和m/z 302.8可作为丙溴磷质谱分析的定性、定量确证离子;结合各样品前处理方法,丙溴磷的添加回收率均在80%以上,相对标准偏差在1.05%~9.65%之间,检测灵敏度达μg/kg水平。这表明LC-MS/MS技术能达到我国农药残留试验准则的相关规定,可用于水稻生产中丙溴磷的残留的检测。