47 resultados para asteroids: individual: (153591) 2001 SN263


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简介并分析最近几年半导体学科基金项目申请和资助的发展趋势以及2001年半导体学科基金申请与资助概况,并附2001年半导体学科批准资助的面上及重点项目,供有关科技工作者参考。

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In this paper,the development of Individual-based Spatial Explicit Landscape Model was outlined at first.Then several issues,pertaining to develop Individual-based Spatial Explicit Landscape Models,were discussed in details.And at last,the application perspectives of such models were illustrated,including animal movement,plant competition and landscape change.This study has relatively important significance guiding roles in developing Individual-based Spatial Explicit Landscape Model in our country and in landscape management.

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Affinity chromatography is unique among separation methods as it is the only technique that permits the purification of proteins based on biological functions rather than individual physical or chemical properties. The high specificity of affinity chromatography is due to the strong interaction between the ligand and the proteins of interest. Membrane separation allows the processing of a large amount of sample in a relatively short time owing to its structure, which provides a system with rapid reaction kinetics. The integration of membrane and affinity chromatography provides a number of advantages over traditional affinity chromatography with porous-bead packed columns, especially with regard to time and recovery of activity. This review gives detailed descriptions of materials used as membrane substrates, preparation of basic membranes, coupling of affinity ligands to membrane supports, and categories of affinity membrane cartridges. It also summarizes the applications of cellulose/glycidyl methacrylate composite membranes for proteins separation developed in our laboratory. (C) 2001 Elsevier Science B.V. All rights reserved.

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根据黄土高原13条流域的降雨资料,分三种雨型即局地强对流条件引起的小范围、短历时、高强度的局地性暴雨(A型暴雨),峰面型降雨夹有局地雷暴性质的较大范围、中历时、中强度暴雨(B型暴雨),峰面型降雨引起的大面积、长历时、低强度暴雨(C型暴雨);选用流域面雨量离差系数Cv、流域降雨不均匀系数η和流域最大点与最小点降雨量比值系数α三种指标,分析了次降雨空间分布的不均匀性。

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Plant traits and individual plant biomass allocation of 57 perennial herbaceous species, belonging to three common functional groups (forbs, grasses and sedges) at subalpine (3700 m ASL), alpine (4300 m ASL) and subnival (>= 5000 m ASL) sites were examined to test the hypothesis that at high altitudes, plants reduce the proportion of aboveground parts and allocate more biomass to belowground parts, especially storage organs, as altitude increases, so as to geminate and resist environmental stress. However, results indicate that some divergence in biomass allocation exists among organs. With increasing altitude, the mean fractions of total biomass allocated to aboveground parts decreased. The mean fractions of total biomass allocation to storage organs at the subalpine site (7%+/- 2% S.E.) were distinct from those at the alpine (23%+/- 6%) and subnival (21%+/- 6%) sites, while the proportions of green leaves at all altitudes remained almost constant. At 4300 m and 5000 m, the mean fractions of flower stems decreased by 45% and 41%, respectively, while fine roots increased by 86% and 102%, respectively. Specific leaf areas and leaf areas of forbs and grasses deceased with rising elevation, while sedges showed opposite trends. For all three functional groups, leaf area ratio and leaf area root mass ratio decreased, while fine root biomass increased at higher altitudes. Biomass allocation patterns of alpine plants were characterized by a reduction in aboveground reproductive organs and enlargement of fine roots, while the proportion of leaves remained stable. It was beneficial for high altitude plants to compensate carbon gain and nutrient uptake under low temperature and limited nutrients by stabilizing biomass investment to photosynthetic structures and increasing the absorption surface area of fine roots. In contrast to forbs and grasses that had high mycorrhizal infection, sedges had higher single leaf area and more root fraction, especially fine roots.