989 resultados para ddc:780


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对柴达木盆地的西伯利亚白刺和唐古特白刺不同部位中氨基酸含量作了分析比较,并进行了营养评价。白刺中富含蛋白质,含有18种氨基酸,其中有人体必需的8种氨基酸,白刺果汁中的必需氨基酸含量远高于沙棘果汁。两种白刺的蛋白质和各氨基酸在各部位中含量分布相似,但因种的差异,第一限制性氨基酸稍有差别。

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卡拉麦里山有蹄类自然保护区是世界著名的荒漠有蹄类自然保护区, 区内有蒙古野驴(E. hemionus)、鹅喉羚(G. subgutturosa)、盘羊(Ovis ammon)以及近期野放的普氏野马(E. przewalski)。经过多年有效保护和管理,区内蒙古野驴及鹅喉羚种群得到恢复并有较大增长。从2006年开始,我们在该保护区开展了蒙古野驴和鹅喉羚的食性构成、社群结构、种群密度、卧息及采食生境利用、季节性栖息地利用等方面的研究。主要结果如下: 采用粪样显微分析技术研究了蒙古野驴、鹅喉羚与家羊、家马和家骆驼3种家养动物春季、秋季和冬季食性组成及食物生态位。结果发现:(1) 该区域的蒙古野驴、鹅喉羚和家畜所采食的植物科数和种数都不相同,针茅、驼绒藜、蒿和梭梭在各自食谱中所占的比例不同, 但蒙古野驴、鹅喉羚和家畜主要采食针茅、驼绒藜、蒿和梭梭;(2) 春季、秋季和冬季这些野生与家养草食动物两两之间的食物生态位重叠均在0.8以上,最低为0.832(冬季:鹅喉羚和家马),最高达到0.986(秋季:蒙古野驴和家羊;秋季:家马和家羊)。五种有蹄类之间的食物生态位重叠度也达到了0.3以上。表明在卡拉麦里山有蹄类自然保护区,上述野生动物及季节性进入该自然保护区的家畜之间均存在食物竞争。冬季积雪深,食物短缺, 荒漠有蹄类易因冻饿及疾病等造成死亡。因此,应采取限制秋冬季进入该自然保护区家畜数量及调整放牧区域等保护管理措施,对该区域荒漠有蹄类实施有效保护。 对蒙古野驴和鹅喉羚的集群行为进行了初步研究。将鹅喉羚或蒙古野驴集群划分为雌性群、雄性群、母仔群、雌雄混群和独羚或独驴5种类型。共统计蒙古野驴556群次,计8235匹次。其中,雌雄混群223群次, 占40%, 为最多的集群类型;其余为雄性群(24%)、独驴(19%)、雌性群(11%)和母仔群(6% )。不同集群大小的比例差异极显著 (P=0.000)。其中2-30匹的集群占69%,独驴占18%,其余为13%。最大集群为266匹。除独驴外,其余4种集群类型的集群大小存在极显著差异。独驴作为一种特殊的集群类型,其占雄性个体的比例达63%,说明雄性个体比雌性更容易形成独驴。观察记录到鹅喉羚1286群次,计9148只次。其中,雌雄混群459群次, 占35%,为最多的集群类型;其余为独羚(18%)、母仔群(18%)、雄性群(17%)和雌性群(12%)。不同大小集群的比例差异极显著(P=0.000),其中2一15头的集群占73%, 16头以上集群占42%,独羚仅占3%,不同集群大小差异也极为显著(P=0.000)。除独羚外,其余4种集群类型的集群大小存在极显著差异。独羚作为一种特殊的集群类型,其雌性个体的比例占到55%,因此, 不能说明雄性比雌性更容易形成独羚。 分四个季节采用截线取样法,用DISTANCE5.0估计了蒙古野驴、鹅喉羚的密度和遇见率。根据DISTANCE5.0计算,该区域春季蒙古野驴种群密度为0.55±0.14匹/km2 (平均数±标准差,下同),夏季为0.60±0.13匹/km2,秋季为0.78±0.19匹/km2和冬季为0.54±0.14匹/km2。春季、夏季、秋季和冬季的鹅喉羚种群密度分别为1.14± 0.18头/km2,0.95±0.12头/km2,1.08±0.18头/km2和1.54±0.31头/km2。将这些结果与本区域不同时期及不同地域的蒙古野驴、鹅喉羚密度和遇见率数据进行了比较对比。截线取样法为研究干旱地区的有蹄类动物提供了一种标准方法,本研究结果为卡拉麦里自然保护区蒙古野驴和鹅喉羚的长期监测提供了基础数据。 采用样方法研究了鹅喉羚夏季和冬季卧息生境选择。夏季测定了49个卧迹样方,36个对照样方;冬季测定了75个卧迹样方,75个对照样方。研究发现,春季鹅喉羚主要选择平滩、下坡位和无坡位、海拔高度910米以上、与水源距离较远、远离道路、远离居民点、隐蔽级高、中低植被密度和中高草本密度的区域作为卧息生境;而冬季则主要选择山坡、阳坡和半阴半阳坡、中上坡位和下坡位、海拔900~1000m范围、离道路501~1000m以及大于2000m的距离、靠近居民点、中低隐蔽级、中厚度(1.1-3cm)雪深、中高植被密度和中高草本密度的区域作为卧息生境。主成分分析表明,卡拉麦里山鹅喉羚夏季季卧息样方前4个主成分的累积贡献率达到86.57%,第1主成分主要反映卧迹样方的植物密度、草本密度、针茅密度、至最近居民点距离、至永久水源最近距离和海拔。冬季该区域鹅喉羚卧息样方前4个主成分的累积贡献率达到73.88%,第1主成分主要反映卧迹样方的植物密度、草本密度、针茅密度和坡度。 通过设立样方研究了蒙古野驴的采食生境。研究发现,夏季和秋季两个季节蒙古野驴主要在平滩和山沟采食。集中在无坡向的平滩、1001m以上的海拔高度、与水源距离较近、远离道路、远离矿区等人类活动点、植被盖度高、草本盖度高、植物多样性高、草本多样性高(P<0.05)的区域采食。主成分分析表明,夏季影响蒙古野驴采食生境选择的环境因子是植物盖度、草本盖度、针茅盖度、植物密度、草本密度、针茅密度、植物种类、草本种类和禾本科种类。秋季影响蒙古野驴采食生境选择的环境因子是海拔、植物盖度、草本盖度、针茅盖度、植物密度、草本密度、针茅密度、植物种类、草本种类和禾本科种类。 利用卡山保护区不同季节野外种群调查数据,以3S技术为手段,评价了蒙古野驴和鹅喉羚季节性栖息地适宜性。首先把各季节蒙古野驴和鹅喉羚分布点图层,分别和固定水源点图层、道路图层、固定冬牧点图层和矿点图层进行叠加和距离查询,用Vanderploeg & Scavia’s选择指数(Ei*)分析了蒙古野驴和鹅喉羚季节性栖息地选择及其主要影响因素,建立了固定水源点、植被、道路、固定冬牧点和矿点对蒙古野驴和鹅喉羚栖息地影响强度的评价标准。通过缓冲区分析,分别研究了固定水源点、道路、固定冬牧点、矿点对蒙古野驴和鹅喉羚季节性栖息地的影响。通过缓冲区分析,综合研究了与人类活动有关的道路、固定冬牧点和矿点因子对蒙古野驴和鹅喉羚季节性栖息地的影响。最后将固定水源点、植被、道路、固定冬牧点和矿点等5个因子结合起来通过地图综合查询研究分析了这些因子对蒙古野驴和鹅喉羚季节性栖息地的综合影响,在固定水源点较适宜以上范围给出了该保护区蒙古野驴和鹅喉羚季节性不同适宜等级的生境面积。 我们建议采取以下积极措施来保护卡山保护区荒漠生态系统多样性以有效保护该区域内栖息的蒙古野驴和鹅喉羚:提高保护区周边社区政府的认识,提高公众参与自然资源和生物多样性保护的意识;加强水源地建设,积极采取飞播等措施,恢复植被,提高栖息生境质量;逐步限制进入卡拉麦里山越冬渡春的家畜数量;严格进入卡山保护区采矿制度,取缔非法矿业;加强草原围栏生态通道建设;与蒙古国合作建立跨国界的国际自然保护区;建立卡山自然保护区自然资源有偿使用机制;开展长期蒙古野驴和鹅喉羚种群监测。

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以云蒙山变质核杂岩东侧的河防口低角度正断层为研究对象,通过矿物(黑云母)的变形特征和形成环境分析,获得了该断层带上的构造热演化环境:温度为780~860℃,压力约为7.3×10^8-8.6×10^8pa。提出云蒙山变质核杂岩的成因机制是,在区域伸展背景下,处于半固结状态的云蒙山花岗岩在东南侧卷入河防口-水峪伸展型韧性剪切带,使花岗岩发生中高温条件的韧性变形;之后,该韧性剪切带在隆升过程中不断向浅层次过渡,形成了一些浅层次的脆性伸展变形构造。

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富磷过铝质岩浆是过铝质岩浆体系中的一个重要类型,它通常以富P,高ASI[铝饱和指数,Al2O3/(Na2O+K2O+CaO)摩尔比值],贫Fe、Mg、Ca,强烈亏损REE、Th、Y,与稀有金属(W、Sn、Be、Nb、Ta)矿化具有成因联系为特征。富磷过铝质岩浆体系的性状及其演化的地球化学特征、岩浆液态分离、磷酸盐-硅酸盐矿物对平衡对熔体相中磷的制约以及富磷过铝质岩浆-热液体系中微量元素(包括REE)地球化学行为等科学问题尚未得到系统解决,目前更缺乏实验地球化学的直接证据。对上述科学问题的研究、探索,将有助于了解富磷过铝质岩浆体系形成和演化的地球化学特征,有助于揭示磷对微量元素(包括稀有、稀土元素)地球化学行为的影响,这对于理解过铝质岩浆体系成岩、成矿作用过程具有重要的理论和实际意义。 本文以天然钠长花岗岩为初始物,针对上述内容,开展了不同PTX条件下高温高压下实验研究,获得了如下重要认识: 1) 确定了100 MPa条件下磷对过铝质岩浆液相线温度的影响。随着体系中P2O5的含量增大,液相线温度由1.91 wt%P2O5的780 C降至4.83 wt%P2O5的760C、7.71 wt%P2O5的740 C,即体系中每增加1 wt%P2O5,液相线温度降低约7~10 C; 2) 不同PTX条件下的实验产物中均未见不混溶球粒结构、乳滴结构或流动构造,初步推断富磷过铝质岩浆体系中可能不存在单纯由磷引起的岩浆液态分离现象; 3) 锰铝榴石-磷灰石矿物平衡反应制约着形成过铝质初始岩浆中P2O5含量,熔体相中P2O5含量在750 C的0.47~0.80 wt%、830 C的0.35~2.26 wt%范围内。熔体相中的P2O5含量与ASI之间存在二次函数关系(P2O5 wt%=3.5×ASI2-11.3×ASI+9.5 )。锰铝榴石溶解,促使体系中Al2O3活度增大,含锰氟磷灰石的溶解及其端元磷灰石结晶之间的化学平衡,导致熔体相中P2O5的降低,很可能是熔体中P2O5随体系ASI增大而降低的机制。 4) 不同PTX条件下稀有金属元素(W、Sn、Be、Nb、Ta)在流体/熔体相间的分配系数(Dif/m)<<0.1,预示着W、Sn、Be、Nb、Ta强烈富集在富磷过铝质熔体相中。由此,可推测富P过铝质岩浆体系的演化晚期,不太可能分异出富含上述成矿元素的成矿流体。随着岩浆分异演化的进行,残余熔体相中最终导致绿柱石、锆石、锡石、铌钽矿物等矿物饱和结晶,形成有经济意义的花岗岩型或伟晶岩型稀有金属矿床。 5) 不同PTX条件下REE在流体/熔体间的分配系数(DREE)随REE的原子序数增大而逐渐降低,构成右倾的平滑曲线,不存在在Nd-Pm、Gd、Ho-Er处的拐点;Y与Ho在流体/熔体相间分配系数的比值(DY/DHo)约为1,不受体系温度、压力和P2O5含量变化的影响。上述实验结果揭示,富磷过铝质量岩浆演化至岩浆-热液过渡阶段,熔体-流体作用不会导致Y-Ho间的分异,不会引起REE间的分异,因此,富磷过铝质岩浆演化晚期的熔体-流体作用过程不可能是产生稀土“四分组”效应的根本机理。

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2007

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Davison G, Gleeson M, 2006. The effect of 2 weeks vitamin C supplementation on immunoendocrine responses to 2.5 h cycling exercise in man. European Journal of Applied Physiology 97(4): 454-461 RAE2008

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Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária

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http://www.archive.org/details/somebyproductsof013993mbp

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In this thesis, the evanescent field sensing techniques of tapered optical nanofibres and microspherical resonators are investigated. This includes evanescent field spectroscopy of a silica nanofibre in a rubidium vapour; thermo-optical tuning of Er:Yb co-doped phosphate glass microspheres; optomechanical properties of microspherical pendulums; and the fabrication and characterisation of borosilicate microbubble resonators. Doppler-broadened and sub-Doppler absorption spectroscopic techniques are performed around the D2 transition (780.24 nm) of rubidium using the evanescent field produced at the waist of a tapered nanofibre with input probe powers as low as 55 nW. Doppler-broadened Zeeman shifts and a preliminary dichroic atomic vapour laser lock (DAVLL) line shape are also observed via the nanofibre waist with an applied magnetic field of 60 G. This device has the potential for laser frequency stabilisation while also studying the effects of atom-surface interactions. A non-invasive thermo-optical tuning technique of Er:Yb co-doped microspheres to specific arbitrary wavelengths is demonstrated particularly to 1294 nm and the 5S1/2F=3 to 5P3/2Fʹ=4 laser cooling transition of 85Rb. Reversible tuning ranges of up to 474 GHz and on resonance cavity timescales on the order of 100 s are reported. This procedure has prospective applications for sensing a variety of atomic or molecular species in a cavity quantum electrodynamics (QED) experiments. The mechanical characteristics of a silica microsphere pendulum with a relatively low spring constant of 10-4 Nm-1 are explored. A novel method of frequency sweeping the motion of the pendulum to determine its natural resonance frequencies while overriding its sensitivity to environmental noise is proposed. An estimated force of 0.25 N is required to actuate the pendulum by a displacement of (1-2) μm. It is suggested that this is of sufficient magnitude to be experienced between two evanescently coupled microspheres (photonic molecule) and enable spatial trapping of the micropendulum. Finally, single-input borosilicate microbubble resonators with diameters <100 μm are fabricated using a CO2 laser. Optical whispering gallery mode spectra are observed via evanescent coupling with a tapered fibre. A red-shift of (4-22) GHz of the resonance modes is detected when the hollow cavity was filled with nano-filtered water. A polarisation conversion effect, with an efficiency of 10%, is observed when the diameter of the coupling tapered fibre waist is varied. This effect is also achieved by simply varying the polarisation of the input light in the tapered fibre where the efficiency is optimised to 92%. Thus, the microbubble device acts as a reversible band-pass to band-stop optical filter for cavity-QED, integrated solid-state and semiconductor circuit applications.

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info:eu-repo/semantics/published

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Thermal-optical analysis is a conventional method for classifying carbonaceous aerosols as organic carbon (OC) and elemental carbon (EC). This article examines the effects of three different temperature protocols on the measured EC. For analyses of parallel punches from the same ambient sample, the protocol with the highest peak helium-mode temperature (870°C) gives the smallest amount of EC, while the protocol with the lowest peak helium-mode temperature (550°C) gives the largest amount of EC. These differences are observed when either sample transmission or reflectance is used to define the OC/EC split. An important issue is the effect of the peak helium-mode temperature on the relative rate at which different types of carbon with different optical properties evolve from the filter. Analyses of solvent-extracted samples are used to demonstrate that high temperatures (870°C) lead to premature EC evolution in the helium-mode. For samples collected in Pittsburgh, this causes the measured EC to be biased low because the attenuation coefficient of pyrolyzed carbon is consistently higher than that of EC. While this problem can be avoided by lowering the peak helium-mode temperature, analyses of wood smoke dominated ambient samples and levoglucosan-spiked filters indicate that too low helium-mode peak temperatures (550°C) allow non-light absorbing carbon to slip into the oxidizing mode of the analysis. If this carbon evolves after the OC/EC split, it biases the EC measurements high. Given the complexity of ambient aerosols, there is unlikely to be a single peak helium-mode temperature at which both of these biases can be avoided. Copyright © American Association for Aerosol Research.

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Subjective age--the age people think of themselves asbeing--is measured in a representative Danish sample of 1,470 adults between 20 and 97 years of age through personal, in-home interviews. On the average, adults younger than 25 have older subjective ages, and those older than 25 have younger subjective ages, favoring a lifespan-developmental view over an age-denial view of subjective age. When the discrepancy between subjective and chronological age is calculated as a proportion of chronological age, no increase is seen after age 40; older respondents feel 20% younger than their actual age. Demographic variables (gender, income, and education) account for very little variance in subjective age.

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PREMISE OF THE STUDY: We investigated the origins of 252 Southern Appalachian woody species representing 158 clades to analyze larger patterns of biogeographic connectivity around the northern hemisphere. We tested biogeographic hypotheses regarding the timing of species disjunctions to eastern Asia and among areas of North America. METHODS: We delimited species into biogeographically informative clades, compiled sister-area data, and generated graphic representations of area connections across clades. We calculated taxon diversity within clades and plotted divergence times. KEY RESULTS: Of the total taxon diversity, 45% were distributed among 25 North American endemic clades. Sister taxa within eastern North America and eastern Asia were proportionally equal in frequency, accounting for over 50% of the sister-area connections. At increasing phylogenetic depth, connections to the Old World dominated. Divergence times for 65 clades with intercontinental disjunctions were continuous, whereas 11 intracontinental disjunctions to western North America and nine to eastern Mexico were temporally congruent. CONCLUSIONS: Over one third of the clades have likely undergone speciation within the region of eastern North America. The biogeographic pattern for the region is asymmetric, consisting of mostly mixed-aged, low-diversity clades connecting to the Old World, and a minority of New World clades. Divergence time data suggest that climate change in the Late Miocene to Early Pliocene generated disjunct patterns within North America. Continuous splitting times during the last 45 million years support the hypothesis that widespread distributions formed repeatedly during favorable periods, with serial cooling trends producing pseudocongruent area disjunctions between eastern North America and eastern Asia.

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We study the generation of supercontinua in air-silica microstructured fibers by both nanosecond and femtosecond pulse excitation. In the nanosecond experiments, a 300-nm broadband visible continuum was generated in a 1.8-m length of fiber pumped at 532 nm by 0.8-ns pulses from a frequency-doubled passively Q-switched Nd:YAG microchip laser. At this wavelength, the dominant mode excited under the conditions of continuum generation is the LP 11 mode, and, with nanosecond pumping, self-phase modulation is negligible and the continuum generation is dominated by the interplay of Raman and parametric effects. The spectral extent of the continuum is well explained by calculations of the parametric gain curves for four-wave mixing about the zero-dispersion wavelength of the LP11 mode. In the femtosecond experiments, an 800-nm broad-band visible and near-infrared continuum has been generated in a 1-m length of fiber pumped at 780 nm by 100-fs pulses from a Kerr-lens model-locked Ti:sapphire laser. At this wavelength, excitation and continuum generation occur in the LP01 mode, and the spectral width of the observed continuum is shown to be consistent with the phase-matching bandwidth for parametric processes calculated for this fiber mode. In addition, numerical simulations based on an extended nonlinear Schrödinger equation were used to model supercontinuum generation in the femtosecond regime, with the simulation results reproducing the major features of the experimentally observed spectrum. © 2002 Optical Society of America.