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1.
Splitting of the sun's global oscillation frequencies by large-scale flows can be used to investigate how rotation varies with radius and latitude within the solar interior. The nearly uninterrupted observations by the Global Oscillation Network Group (GONG) yield oscillation power spectra with high duty cycles and high signal-to-noise ratios. Frequency splittings derived from GONG observations confirm that the variation of rotation rate with latitude seen at the surface carries through much of the convection zone, at the base of which is an adjustment layer leading to latitudinally independent rotation at greater depths. A distinctive shear layer just below the surface is discernible at low to mid-latitudes.  相似文献   

2.
The Global Oscillation Network Group (GONG) project estimates the frequencies, amplitudes, and linewidths of more than 250,000 acoustic resonances of the sun from data sets lasting 36 days. The frequency resolution of a single data set is 0.321 microhertz. For frequencies averaged over the azimuthal order m, the median formal error is 0.044 microhertz, and the associated median fractional error is 1.6 x 10(-5). For a 3-year data set, the fractional error is expected to be 3 x 10(-6). The GONG m-averaged frequency measurements differ from other helioseismic data sets by 0.03 to 0.08 microhertz. The differences arise from a combination of systematic errors, random errors, and possible changes in solar structure.  相似文献   

3.
Data from the Global Oscillation Network Group (GONG) project and other helioseismic experiments provide a test for models of stellar interiors and for the thermodynamic and radiative properties, on which the models depend, of matter under the extreme conditions found in the sun. Current models are in agreement with the helioseismic inferences, which suggests, for example, that the disagreement between the predicted and observed fluxes of neutrinos from the sun is not caused by errors in the models. However, the GONG data reveal subtle errors in the models, such as an excess in sound speed just beneath the convection zone. These discrepancies indicate effects that have so far not been correctly accounted for; for example, it is plausible that the sound-speed differences reflect weak mixing in stellar interiors, of potential importance to the overall evolution of stars and ultimately to estimates of the age of the galaxy based on stellar evolution calculations.  相似文献   

4.
Doppler velocity observations obtained by the Global Oscillation Network Group (GONG) instruments directly measure the nearly steady flows in the solar photosphere. The sun's differential rotation is accurately determined from single observations. The rotation profile with respect to latitude agrees well with previous measures, but it also shows a slight north-south asymmetry. Rotation profiles averaged over 27-day rotations of the sun reveal the torsional oscillation signal-weak, jetlike features, with amplitudes of 5 meters per second, that are associated with the sunspot latitude activity belts. A meridional circulation with a poleward flow of about 20 meters per second is also evident. Several characteristics of the surface flows suggest the presence of large convection cells.  相似文献   

5.
本试验在离体和活体条件下,观察了宫复康-一种中药口服液对家兔子宫肌收缩活动的影响,结果表明,在以上两种情况下,宫复康均能使家兔子宫肌收缩和频率显著提高(P〈0.05)。  相似文献   

6.
Lunar samples contain mercury, which may be volatilized at lunar daytime temperatures. Such mercury may constitute part of the tenuous lunar atmosphere. If mercury can escape from the atmosphere by a nonthermal mechanism, an interior reservoir or exterior sources (such as meteorite infall or solar wind, or both) are required to replenish it. Core samples exhibit an increase in surface-related mercury with depth, which suggests that a cold trap exists below the surface. The orientation of rocks on the lunar surface may be inferred by differences in the amounts of surface-related mercury found on exterior and interior samples.  相似文献   

7.
Hydrophobic organization of membrane proteins   总被引:31,自引:0,他引:31  
Membrane-exposed residues are more hydrophobic than buried interior residues in the transmembrane regions of the photosynthetic reaction center from Rhodobacter sphaeroides. This hydrophobic organization is opposite to that of water-soluble proteins. The relative polarities of interior and surface residues of membrane and water soluble proteins are not simply reversed, however. The hydrophobicities of interior residues of both membrane and water-soluble proteins are comparable, whereas the bilayer-exposed residues of membrane proteins are more hydrophobic than the interior residues, and the aqueous-exposed residues of water-soluble proteins are more hydrophilic than the interior residues. A method of sequence analysis is described, based on the periodicity of residue replacement in homologous sequences, that extends conclusions derived from the known atomic structure of the reaction center to the more extensive database of putative transmembrane helical sequences.  相似文献   

8.
追溯了国外室内植物的起源,盆栽是一个历史性的转折。温室的出现为植物进入室内提供了条件,为室内植物创造适宜的生长环境,其中培育暖房和橙屋都是早期温室的一种形式。阐述了它的历史,在室内植物的产生过程中,植物收集者们的功劳是最大的,19世纪后半期是引进全世界各地室内植物到欧洲的鼎盛时期,植物收集者的贡献不可忽视。在所有收集者们中最有名的两个姓氏是Joseph和Veitch。室内植物令人惊奇的是,各种不同气候带的植物都可以在同一个环境中生长,使得室内的植物物种极为丰富。随着室内环境的改善,可以在室内生长的植物种类将会更多。  相似文献   

9.
园林植物对室内环境能起到很好的装饰和美化作用。该研究从人性化角度论述园林植物在室内环境设计中的作用及应用方式,总结出园林植物在人性化室内环境设计中的应用规则。  相似文献   

10.
图书馆建筑环境对人文精神的体现   总被引:7,自引:0,他引:7  
王敏 《农业图书情报学刊》2006,18(12):114-115,121
图书馆环境包括建筑外环境、内环境以度服务环境3方面。文章提出了图书馆建筑环境对人文精神的体现.应当从馆舍建筑的外环境和内环境两方面入手:应凸显人文关怀的结构设计理念;营造优美环保的绿色环境;室内环境布局、装饰要蕴涵审美情趣,设施建以致用;保障健康的室内空气质量,并提出了如何营造具有人文关怀的服务环境。  相似文献   

11.
The distinct properties of fluorous phases are practically useful for separation, purification, and reaction control in organic synthesis. Here, we report the formation of a liquid-like fluorous droplet, composed of 24 perfluoroalkyl chains confined in the interior of a 5-nanometer-sized, roughly spherical shell that spontaneously assembled in solution from 12 palladium ions and 24 bridging ligands. Crystallographic analysis confirmed the rigid shell framework and amorphous interior. Perfluoroalkanes can dissolve in this well-defined fluorous phase, whereas they can hardly dissolve in a surrounding polar organic solution, and their solubility (up to approximately eight perfluoroalkane molecules per spherical complex) can be finely controlled by tuning the length of perfluoroalkyl chains tethered to the shell.  相似文献   

12.
Hydrophobicity of amino acid residues in globular proteins   总被引:49,自引:0,他引:49  
During biosynthesis, a globular protein folds into a tight particle with an interior core that is shielded from the surrounding solvent. The hydrophobic effect is thought to play a key role in mediating this process: nonpolar residues expelled from water engender a molecular interior where they can be buried. Paradoxically, results of earlier quantitative analyses have suggested that the tendency for nonpolar residues to be buried within proteins is weak. However, such analyses merely classify residues as either "exposed" or "buried." In the experiment reported in this article proteins of known structure were used to measure the average area that each residue buries upon folding. This characteristic quantity, the average area buried, is correlated with residue hydrophobicity.  相似文献   

13.
曾丽娟  吴健平 《安徽农业科学》2010,38(18):9823-9825
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。  相似文献   

14.
The fine structure and dynamics of sunspots and the strong outflow in their outer filamentary part--the penumbra--have puzzled astronomers for more than a century. Recent theoretical models and three-dimensional numerical simulations explain the penumbral filaments and their radiative energy output as the result of overturning convection. Here, we describe the detection of ubiquitous, relatively dark downward flows of up to 1 kilometer per second (km/s) in the interior penumbra, using imaging spectropolarimetric data from the Swedish 1-meter Solar Telescope. The dark downflows are omnipresent in the interior penumbra, distinguishing them from flows in arched flux tubes, and are associated with strong (3 to 3.5 km/s) radial outflows. They are thus part of a penumbral convective flow pattern, with the Evershed flow representing the horizontal component of that convection.  相似文献   

15.
热带雨林片断植物叶温边缘效应的初步分析   总被引:4,自引:0,他引:4  
在西双版纳地区一块面积为 3hm2 热带干性季节性雨林片断的南向林缘 ,观测了林内至林外水平样带上的植物叶温及其它小气候要素 .结果表明 ,植物叶温的边缘效应影响范围从林内 2 0m至林外 16m ,这种水平变化梯度尤以林缘附近 (林内 12m至林外 8m)最大 .从林内至林外 ,植物叶温 (Tl)依次表现出气温 (Ta)型 (Ta>Tl)、中间型 (Ta=Tl)和辐射型 (Tl>Ta) .探讨了植物叶温与气温的关系 ,并讨论了植物叶温边缘效应的生态学影响 .  相似文献   

16.
Measurements by the Galileo probe support the possibility that the zonal winds in Jupiter's atmosphere originate from convection that takes place in the deep hydrogen-helium interior. However, according to models based on recent opacity data and the probe's temperature measurements, there may be radiative and nonconvective layers in the outer part of the jovian interior, raising the question of how deep convection could extend to the surface. A theoretical model is presented to demonstrate that, because of predominant rotational effects and spherical geometry, thermal convection in the deep jovian interior can penetrate into any outer nonconvective layer. These penetrative convection rolls interact nonlinearly and efficiently in the model to generate and sustain a mean zonal wind with a larger amplitude than that of the nonaxisymmetric penetrative convective motions, a characteristic of the wind field observed at the cloud level on Jupiter.  相似文献   

17.
Silicate aggregates, including large single crystals of potassium feldspar as long as 11 centimeters and sodium feldspar, are embeded in the surface of the medium octahedrite Colomera. Silicate nodules in the interior appear to be much smaller (about 0.3 centimeter). Glass nodules are abundant both on the external surface and in the interior. These observations are evidence that some iron meteorites formed as segregations within a silicate matrix and did not originate in a metallic core.  相似文献   

18.
Influence of interior packing and hydrophobicity on the stability of a protein   总被引:18,自引:0,他引:18  
Protein interiors contain many tightly packed apolar atoms in a nearly crystalline state. Both shielding of apolar atoms from solvent and efficient interior packing arrangements affect protein stability, but their relative importance is unclear. To separate these effects, the stabilities of wild-type and mutant gene V proteins from bacteriophage fl were studied by measuring resistance to denaturation. The effects of subtle interior packing changes, both separate from and combined with changes in buried side chain hydrophobicity, were measured. For the interior apolar-to-apolar substitutions studied, the two effects were of the same magnitude and alteration of packing without accompanying hydrophobicity changes substantially destabilized the protein.  相似文献   

19.
20世纪以来,多层建筑和室内空调设备出现后,室内空间与室外自然风景的联系越来越少了.而与自然的隔绝、脱离的日趋严重,导致现代人的体能下降.因此,有人提出了回归自然的主张,怀念日出而作、日落而息与自然共呼吸的生活方式,在当前引起了很大的反响.室内植物是室内坏境改造的关键因素,此文在论述了其重要作用的基础上,深入地阐述了室内植物目前的主要应用形式和设计时需要遵循的基本原则,以及提出了一些植物品种以供进行室内植物景观设计时参考.  相似文献   

20.
在返白系小麦叶色由绿变白的过程中,叶绿体结构发生退化。返白初期,出现大量的嗜饿小滴,基粒排列混乱,垛叠层数异常增多或减少,并且发现类囊体有肿大量的嗜胀现象,粒消失。返白中期,叶绿体中呈现空化现象,内部结构逐渐解体。到叶片继而,基全白时期,整个叶绿体变为低电子密度的囊泡状结构。在叶片由自复绿的过程中,叶绿体的这些变化又可逆转,内部结构又重现,基粒迅速形成,排列也较规则,整个叶绿体结构很快恢复正常。在整个返白阶段中,叶细胞中的其它内部结构如中央大液泡等也发生了一定的变化。  相似文献   

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