989 resultados para S-29
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Objectives of the workshop included; introduction to various Marine Protected Area (MPA) tools with a focus on Management Effectiveness Assessment Tool (MEAT); report on selected MPAs in Bangladesh; undertake initial assessments using MEAT; and develop workplans for other MPAs
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The main objective of the visit was to share the success of Marine Protected Area (MPA) management in Malaysia with Bangladeshi counterparts, representatives of donor organizations, NGOs and researchers.
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记述了在中国6个典型地带土壤中鉴定到的隶属于动基片纲的29种纤毛虫,其中5种为中国土壤原生动物新记录种.这些种类是:陆生拟裸口虫,恼斜板虫,吻瓶口虫,双核管形虫,琴刀口虫,长刀口虫,长尾刀口虫,斜叶苔叶虫,神螺流苏虫,土壤肾形虫,三分肾形虫,背沟肾形虫,无规肾形虫,直立肾形虫,粗糙拟肾形虫,莫氏拟肾形虫,贪食阔庭虫,大撕拉虫,吻吴氏虫,澳洲吴氏虫,大口匙口虫,尖锐密粒虫,卡氏颠毛虫,小拟匙口虫,尖锐篮环虫,丛林拟篮环虫,有肋薄咽虫,弧形微秀体虫和凤冠齿扇虫.
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A comparative limnological study was carried out to present a snapshot of crustacean zooplankton communities and their relations to environmental factors to test whether there is a consistent relationship between crustacean biomass and trophic indicators among lake groups with similar trophic conditions. The study lakes showed a wide range of trophic status, with total phosphorus (TP) ranging from 0.008 to 1.448mgL(-1), and chlorophyll a from 0.7 to 146.1 mu g L-1, respectively. About 38 species of Crustacea were found, of which Cladocera were represented by 25 taxa (20 genera), and Copepoda by 13 taxa (I I genera). The most common and dominant species were Bosmina coregoni, Moina micrura, Diaphanosoma brachyurum, Cyclops vicinus, Thermocyclops taihokuensis, Mesocyclops notius and Sinocalanus dorrii. Daphnia was rare in abundance. Canonical correspondence analysis showed that except for four species (D. hyalina, S. dorrii, C. vicinus and M. micrura), almost all the dominant species had the same preference for environmental factors. Temperature, predatory cyclopoids and planktivorous fishes seem to be the key factors determining species distribution. TP was a relatively better trophic indicator than chlorophyll a to predict crustacean biomass. Within the three groups of lakes, however, there was no consistent relationship between crustacean biomass and trophic indicators. The possible reason might be that top-down and bottom-up control on crustaceans vary with lake trophic state. The lack of significant negative correlation between crustacean biomass and chlorophyll a suggests that there was little control of phytoplankton biomass by macrozooplankton in these shallow subtropical lakes. (c) 2007 Elsevier GmbH. All rights reserved.
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We demonstrate 1.25-1.29 mu m metamorphic laser diodes grown on GaAs by molecular beam epitaxy (MBE) using an alloy-graded buffer layer (GBL). Use of Be in the GBL is effective to reduce surface/interface roughness and improves optical quality. The RMS surface roughness of the optimized metamorphic laser is only two atomic monolayers for 1 x 1 mu m(2). Cross-sectional transmission electron microscopy (TEM) images confirm that most dislocations are blocked in the GBL. Ridge waveguide lasers with 4 mu m wide ridge were fabricated and characterized. The average threshold current under the pulsed excitation is in 170-200 mA for a cavity length of 0.9-1.5 mm. This value can be further reduced to about 100 mA by high-reflectivity coating. Lasers can work in an ambient temperature up to at least 50 degrees C. (c) 2006 Elsevier B.V. All rights reserved.
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于2010-11-23批量导入
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<正>近年来,双质子发射的现象被广泛研究。~(29)S核最外层两个质子处于2s1/2轨道,可能存在这种奇特的行为。先前的实验表明,~(29)S+~(28)Si的总反应截面有着异常大的值。这意味着~(29)S中最后2
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An experiment of a S-29 beam bombarding a Au-197 target at an energy of 49.2 MeV/u has been performed to study the two-proton correlated emission from S-29 excited states. Complete-kinematics measurements were carried out in the experiment. The relative momentum, opening angle, and relative energy of two protons, as well as the invariant mass of the final system, were deduced by relativistic-kinematics reconstruction. The Si-27-p-p coincident events were picked out under strict conditions and the phenomenon of p-p correlations was observed among these events. The mechanisms of two-proton emission were analyzed in a simple schematic model, in which the extreme decay modes like He-2 cluster emission, three-body phase-space decay, and two-body sequential emission were taken into account. Associated with the Monte Carlo simulations, the present results show that two protons emitted from the excited states between 9.6 MeV and 10.4 MeV exhibit the features of He-2 cluster decay with a branching ratio of 29(-11)(+10)%.
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L-shell X-ray spectra of Mo surface induced by Xe25+ and Xe29+ were measured. The X-ray intensity was obtained in the kinetic energy range of the incident ions from 350 to 600 keV. The relationship of X-ray intensity with kinetic energy of the projectile and its charge state were studied, and the simple explanation was given.
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A series of experiments have been performed by complete kinematics measurements to study two-proton (2p) correlated emission from the excited states of Ne-17,Ne-18 and S-28,S-29 via the Coulomb excitation by bombarding on Au-197 target. 2p and residua coincident events were picked Out under strict conditions. Visible p-p correlations were observed. It is shown that 2p can be emitted from the high-lying excited states. 2p halo may lead to 2p emission with large spectroscopy factor for the states close to or beyond the threshold.
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The nonstoichimetric Ba0.92Y2.15F8.29 submicrospheres that piled up by nanoparticles have been prepared via a solution-based method in a hydrothermal environment. The size distribution of the submicrospheres could be tuned by varying the amount of BaCl2. The fluoride source NaBF4 plays an important role in the formation of the submicrospheres. The chelator ethylenediaminetetraacetic acid regulates the growth of the primary nanoparticles as well as the aggregated submicrospheres. The photoluminescence properties of different concentrations of Eu3+-doped Ba0.92Y2.15F8.29 were investigated and the results revealed that the 8% concentration of Eu3+ ions is the optimum doping concentration and the Y3+ ions occupy the site of inversion symmetry.
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杂原子ZSM-5分子筛对某些特定的催化反应具有很高的活性和选择性,因而杂原子在分子筛中的存在状态成为人们十分关注的问题,作者曾用许多结构研究方法对杂原子ZSM-5分子筛进行了表征。本文用~(29)Si MAS NMR方法研究了M-ZSM-5 (M=Ga、B、Zn、Ni)分子筛杂原子的存在状态。