检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

弯晶X射线光学(英文)

光学精密工程 2007年第12期15卷 1823-1828页

作者： e.f.rster Institute.f.r Optics and Quantum electronics friedrich Schiller University Jena1 Max Wien Platz 07743 Jena Germany

近年来,人们付出很大精力研制新的具有独特性能的同步辐射装置和自由电子激光器,而飞秒激光等离子源可提供具有高峰值亮度的超短X射线脉冲,用来作为波荡器辐射的补充X射线源。此外,所有最新型的X射线源的诊断和应用也都需要专用X射线光... 详细信息

近年来,人们付出很大精力研制新的具有独特性能的同步辐射装置和自由电子激光器,而飞秒激光等离子源可提供具有高峰值亮度的超短X射线脉冲,用来作为波荡器辐射的补充X射线源。此外,所有最新型的X射线源的诊断和应用也都需要专用X射线光学元件或仪器。X射线光谱测量是激光聚变应用中最重要的等离子诊断方法之一,该方法根据实验目的,可获得单色X射线图像或与空间或时间分辨相组合的高分辨率图像。已经研制出拥有多达10个环状弯晶的高精单色成像仪,用以研究激光聚变实验中的内爆过程并通过获得的数据对等离子体参数的时间分辨图做出评估。大功率飞秒激光器可提供实用的相对价格不高的大功率X射线脉冲源,但需要有发光效率,能量分布,以及热电子传输方面的信息来实现理想K层辐射线或者连续X射线输出的最大化,以便得到相当于同步辐射输出的峰值亮度。把这些新的射线源与弯晶光学元件相组合,可完成亚皮秒时间量级的衍射实验。激光泵浦的X射线探针实验已经展示了若干晶体在250 fs内的结构变化。作者所在研究所使用光线追踪和布拉格反射方法设计了1D或2D或1D与2D结合的弯晶X射线光学仪器。在仪器制备过程中,非常注重晶体完整,反射选择的优化,弯曲精确,以及成像和反射特性的测量,还使用X射线形貌相机和衍射仪对分析器晶体的相关特性做了测试。

关键词： X射线光学弯晶 X射线诊断激光产生等离子体 X射线衍射

Juicy Stories on female Reproductive Tissue Development: Coordinating the Hormone.f.ows

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Plant Biology 2013年第9期55卷 847-863页

作者： Veronica A.Grieneisen Athanasius f.M.Marée Lars φstergaard Computational and Systems Biology John Innes Centre Norwich Research ParkNorwich NR4 7UH UK Crop Genetics John Innes Centre Norwich Research ParkNorwich NR4 7UH UK

In the past 20-30 years, developmental biologists have made tremendous progress in identifying genes required for the specifica-tion of individual cell types of an organ and in describing how they interact in genetic networks. In comparison, very little is known about the mechanisms that regulate tissue polarity and overall organ patterning. Gynoecia and fruits from members of the Brassicaceae.f.mily of flowering plants provide excellent model systems to study organ patterning and tissue specification because they become partitioned into distinct domains whose.f.rmation is determined by polarity establishment both at a cellular and whole tissue level. Interactions among key regulators of Arabidopsis gynoecium and fruit development have revealed a network of upstream transcription factor activities required for such tissue differentiation. Regulation of the plant hormone auxin is emerging as both an immediate downstream output and input of these activities, and here we aim to provide an overview of the current knowledge regarding the link between auxin and female reproductive development in plants. In this review, we will also demonstrate how available data can be exploited in a mathematical modeling approach to reveal and understand the.f.edback regulatory circuits that underpin the polarity establishment, necessary to guide auxin flows.

关键词： Auxin dynamics brassicaceae cell and tissue polarity fruit gynoecium mathematical modelling organ patterning ROPs wavepinning

在线全文

学校读者我要写书评

暂无评论

植物的缺铁失绿症

天津农业科学 1981年第1期 23-28页

作者： e.f.沃里海姆邢金铭

植物缺铁失绿病是石灰性土壤常见的营养缺乏病。天津地区常见的果树“黄叶病”即为此病。据译者1963—1964年调查,天津地区不同土壤类型发病情况如表。患病树生长势衰退,严重减产,一般达50％,有的甚至绝收。全年6、8、10月三次病情消长... 详细信息

植物缺铁失绿病是石灰性土壤常见的营养缺乏病。天津地区常见的果树“黄叶病”即为此病。据译者1963—1964年调查,天津地区不同土壤类型发病情况如表。患病树生长势衰退,严重减产,一般达50％,有的甚至绝收。全年6、8、10月三次病情消长调查表明,发病率通常10月最高,发病指数8—9月最高。近年此病日趋严重。其他园林植物和农作物也有发生。为进一步了解此病发生规律,特从《植物和土壤的诊断标准》一书中选译此文,供参考。

关键词：植物缺铁柑桔叶脉水果褪绿病失绿病酸性土酸性土壤石灰岩土石灰性土壤叶绿素含量

Bound in continuum states and induced transparency in mesoscopic demultiplexer with two outputs

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2020年第12期29卷 429-437页

作者： Z Labdouti T Mrabti A Mouadili e H el Boudouti f fethi B Djafari-Rouhani LPMR Dèpartement de PhysiqueFacultèdes SciencesUniversitèMohammed IOujdaMorocco LSTA Dèpartement de PhysiqueFacultèPolydisciplinaire de LaracheUniversitèAbdelmalek EssaadiTètouanMorocco LPMCeR Dèpartement de PhysiqueFacultèdes Sciences et Techniques de MohammediaUniversitèHassan IICasablancaMorocco IeMN UMR CNRS 8520UFR de PhysiqueUniversitède Lille59655 Villeneuve d'AscqFrance

We investigate the electronic transport in a simple mesoscopic cross structure made of two wires(stubs)grafted at the same point along a quantum *** show that the structure may exhibit important phenomena such as bound in continuum(BIC)*** states are transformed into electromagnetically induced transparency(eIT)resonance by detuning slightly the lengths of the *** last phenomenon is used to propose and study a mesoscopic demultiplexer device with an input waveguide and two output *** give closed-form expressions of the geometrical parameters that allow a selective transfer of a given state in the.f.rst waveguide without perturbing the second *** e.f.ct of temperature on the transmission resonances is also examined by using Landauer-Büttiker *** analytical results of the dispersion relation and transmission and reflection coe.f.cient are obtained using the Green's function method.

关键词： mesoscopic structure demultiplexer device bound states in continuum(BIC) eIT resonance

Infuence of elemental composition in environmental impacts of steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2020年第5期27卷 598-607页

作者： e.Batuecas C.Mayo R.Diaz f.J.Perez Thermal and fluid engineering Department Carlos III University of Madrid28911 LeganesMadridSpain Chemical and Materials engineering Department Complutense University of Madrid28040 MadridSpain Technical Sciences and engineering UDIMA University28400 Collado VillalbaMadridSpain。

The environmental behavior of four steels was *** the operation phase of concentrating solar power plants,steels withstand high temperature because of its contact with molten ***,choosing the steel type.f.r the molten salt tanks remains a great *** the cold tank,carbon steel is usually used although an approach with low chromium content steel is being studied for these ***,in high temperature applications,such as hot store tank,austenitic stainless steel is the most frequent ***,ferritic steel is being considered as a promising material in these *** many researchers studied the steel technical properties without considering their environmental damages,this work aimed to introduce the environmental aspects into the material choice by using the life cycle assessment *** one hand,the results showed the environmental adequacy of carbon steel against low chromium content *** the other hand,the results obtained in those steels suitable in high temperature application revealed signifcant environmental benefts from the.f.rritic steel instead of the austenitic steel.

关键词： Renewable energy Concentrating solar power Life cycle assessment Molten salt ferritic steel Austenitic steel

Luminous Activity Study of a Long Atmospheric Pressure DBD Afterglow

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Plasma Science and Technology 2007年第6期9卷 678-681页

作者： e.PANOUSIS f.CLeMeNT N.SPYROU J.f.LOISeAU C.MONGe B.HeLD Laboratory of Gas electronics and Plasmas-Pau University 64000 PanFrance Electrotechnic Materials LaboratoryUniversity of Patras26500 Patras-RioGreece Laboratory of Gas electronics and Plasmas-Pau University 64000 PanFrance electrotechnic Materials Laboratory University of Patras26500 Patras-RioGreece

The experimental work reported here is devoted to the study of the luminous activity of a long dielectric barrier discharge （DBD） afterglow at atmospheric pressure. The discharge plasma is generated in a commercially available （AcXys Technologies） reactor, using a N2 flow of a few tens SL/min, whereas the luminous afterglow when channelled into a quartz tube extends at a distance of 50 cm, finishing in a luminous arrow at the tube＇s exit. The luminous activity of the afterglow is studied by means of photomultiplier scans and optical emission spectroscopy, revealing an interesting transient phase. An attempt is made to correlate this e.f.ct with the active species＇ creation and destruction mechanisms.

关键词： DBD flowing afterglow optical emission spectroscopy

A Note on Pad Approximants Pairs as Limits of Algebraic Polynomials Pairs of Weighted Best Approximation in Orlicz Spaces

在线全文

学校读者我要写书评

暂无评论

Analysis in Theory and Applications 2015年第3期31卷 253-259页

作者： f.e.Levis Departamento de Matemtica Universidad Nacional de Río Cuarto

In this short note, we show the behavior in Orlicz spaces of best approximations by algebraic polynomials pairs on union of neighborhoods, when the measure of them tends to zero.

关键词： Best approximation pair Pad′e approximant pair Orlicz spaces.

flotation behavior and electronic simulations of rare earth minerals in the presence of dolomite supernatant using sodium oleate collector

在线全文

学校读者我要写书评

暂无评论

Journal of Rare earths 2019年第1期37卷 101-112,M0005页

作者： e.R.L.espiritu G.R.da Silva D.Azizi f.Larachi K.e.Waters Department of Mining and Materials engineering McGill University Department of Chemical engineering Université Laval

Common rare earth(Re) minerals, such as bastnasite and monazite, may be.f.rmed in deposits associated with carbonate gangue, such as calcite and dolomite. Sodium oleate is a widely used collector for the.f.otation of both Re and gangue minerals, which might, therefore, be an ine.f.cient process due to the lack of selectivity of this collector. Since these minerals are also sparingly soluble in solution, they could release their constituent ions into the solution, which could affect the.f.oatability of other minerals. In this study, the interactions of sodium oleate with bastnasite and monazite in the presence of dissolved dolomite species have been investigated. Microflotation tests were carried out to explore the e.f.cts of these dissolved species on the.f.oatability of the Re minerals. Zeta potential measurements and XPS characterization were carried out to understand how the species affect the collector adsorption. To complement these characterizations, density functional theory(DfT) simulations were conducted to investigate the collector-mineral and collector-adsorbed species(on the mineral surface) *** results show that collector-dolomite interaction energy is greater than that of collector-adsorbed species, but lower than collector-monazite interaction energy, explaining the decrease in the minerals' recovery upon exposure to the dissolved mineral species. It is also shown that oleate ions(OI^-) have the strongest interaction with the minerals compared to other oleate species such as acid soap(HOI_2^-) and oleate dimer(OI_2^(2-)). The behavior(strength and selectivity) of sodium oleate towards Re minerals and dolomite, as compared to other Re mineral collectors(such as aromatic hydroxamate), is attributed mainly to the collector's and the minerals' structure. The long hydrocarbon chain of sodium oleate which imparts hydrophobic characteristic to the minerals, makes it stronger collector than ***, sodium oleate(with linear str

关键词： Rare earth minerals Bastnsite Monazite Dolomite Sodium oleate DfT simulation

Carbon isotopes of graphite:Implications on fluid history

在线全文

学校读者我要写书评

暂无评论

Geoscience.f.ontiers 2012年第2期3卷 197-207页

作者： f.J.Luque e.Crespo-feo J.f.Barrenechea L.Ortega Departamento de Cristalografía y Mineralogía facultad de Geología Universidad Complutense de Madrid 28040 MadridSpain Instituto de Geociencias(UCM-CSIC) Jos Antonio Novais 228040 MadridSpain Departamento de Cristalografia y Mineralogia facultad de Geología Universidad Complutense de Madrid28040 MadridSpain Departamento de Cristalografía y Mineralogía facultad de Geología Universidad Complutense de Madrid28040 MadridSpain

Stable carbon isotope geochemistry provides important information for the recognition of funda- mental isotope exchange processes related to the movement of carbon in the lithosphere and permits the elab- oration of models for the global carbon cycle. Carbon isotope ratios in fluid-deposited graphite are powe.f.l tools for unravelling the ultimate origin of carbon （organic matter, mantle, or carbonates） and help to constrain the.f.uid history and the mechanisms involved in graphite deposition. Graphite precipitation in fluid-deposited occurrences results from C02- and/or CH4-bearing aqueous fluids. fluid flow can be considered as both a closed （without replenishment of the.f.uid） or an open system （with renewal of the.f.uid by successive.f.uid batches）. In closed systems, carbon isotope systematics in graphite is mainly governed by Rayleigh precipi- tation and/or by changes in temperature affecting the.f.actionation factor between fluid and graphite. Such processes result in zoned graphite crystals or in successive graphite generations showing, in both cases, isotopic variation towards progressive 13C or 12C enrichment （depending upon the dominant carbon phase in the.f.uid, C02 or CH4, respectively）. In open systems, in which carbon is episodically introduced along the.f.acture systems, the carbon systematics is more complex and individual graphite crystals may display oscillatory zoning because of Rayleigh precipitation or heterogeneous variations of 613C values when mixing of fluids or changes in the composition of the.f.uids are the mechanisms responsible.f.r graphite precipitation.

关键词： Graphite Carbon isotopes Crust C-O-H fluids