534 resultados para 984
Resumo:
以管道理论为基础,运用主轴切割的方法,论述不同年龄小钻杨树体的结构特点。结果表明:树干生物量增加与高度的降低呈线性关系;同一层次内的叶量和枝量间存在显著的线性关系,其关系的确定性不受分层方式的影响;树冠不同层次内的累积叶量与支持的枝干总质量存在显著的线性关系;不同层次的总累积生物量与各层内的树干生物量密度之间的线性关系显著,对不同层次累积树干生物量与各层树干生物量密度进行指数回归,系数介于1.1~1.3,指数介于1~2,表明二者的关系是处于线性和指数关系之间的一种形式;在胸高以上,树干边材断面积与侧枝基部断面积总和呈线性关系,胸高之下线性关系不存在。建立不同年龄小钻杨边材与所支持叶量的树体管道模型,同时测得胸径(D1.3)与心材直径(Dx)间的关系为Dx=0.522 exp(0.169 8D1.3),r=0.984 8。
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Rare earth oxide, neodymium oxide (Nd2O3), CO-catalyzed melt grafting of maleic anhydride (MAH) onto co-polypropylene (co-PP) in the presence of dicumyl peroxide (DCP) was carried out by reactive extrusion. The experimental results reveal that the addition of Nd2O3 as a coagent leads to an enhancement in both MFR and the grafting degree of MAH, along with a simultaneous decrease in the gel content. When the Nd2O3 concentration is 6.0 mmol%, the increment of the grafting degree of MAH maximally is up to about 20% compared with the related system without adding Nd2O3, and the gel content decreases simultaneously to a very low level of about 3%. Attenuated total reflection FTIR (ATR-FTIR) indicates that the gel in the graft copolymers mainly arise from the cross-linking reaction between ethylene units of co-PP. A reasonable reaction mechanism has been put forward on the basis of our experimental results and other mechanisms reported in the literature. We also tentatively explain above results by means of synergistic effect between DCP and Nd2O3, which causes a higher concentration of the macroradical, in particular the tertiary macroradical.
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A new molybdenum-citrato cluster containing [Mo2O2(mu-S)(2)(C6H5O7)(C6H4O7)](5-) anion was synthesized and characterized by elemental analysis, IR, UV-Vis spectra, XPS and X-ray diffraction. The parameters of the crystal structure of the compound are monoclinic, space group P2(1)/c, a = 2. 376 6(5) nm, b = 1. 327 4(3) nm, c = 2. 247 1(5) nm, beta = 118. 21 degrees, V = 6. 247(2) nm(3), Z = 8, D-c = 2. 128 g/cm(3), F(000) = 3 984, mu = 1 694 cm(-1), R = 0. 083 1 and R-2,R-w = 0. 154 9. The anion is binuclear molybdenum-citrato complex with mu(2)-S bridge. Each molybdenum atom pocesesses a distorted octahedral struture, which is coordinated with a terminal oxygen, two sulfur atoms, three oxygen atoms of hydroxyl, alpha-carboxylate, beta-carboxylate from citrate.
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Two new metal-ore supported transition metal complexes, E{M(phen)(2)}(2)(Mo8O26) (M = Ni or CO; phen = 1,10-phenanthroline) are synthesized by a hydrothermal method and characterized by X-ray crystallography, showing that the octamolybdate possesses a novel unprecedented structure and that [M(phen)(2)](2+) units are covalently bonded to the [Mo8O26](4-) cluster.
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The novel poly(aryl ether ketone)s with liquid crystallinity were synthesized by nucleophilic substitution reactions of 4,4'-biphenol and substituted hydroquinone with 4,4'-difluorobenzophenone and their thermotropic liquid crystalline properties were characterized by DSC, PLM and WAXD, The copolymers containing 70% biphenol formed nematic phase while the copolymer containing 50% biphenol exhibited smectic texture, The banded textures were formed after shearing the sample in the nematic liquid crystalline state. The identification of the structures in each mesogenic phase has been carried out by combining WAXD with PLM and DSC.
Resumo:
用红外光谱、紫外可见光谱、循环伏安法等研究了三.(2,4-二特戊基苯氧基)-8-喹淋氧基酞菁铜(简称酞菁铜)和2-十八烷基-7,7,8,8-四氰二甲基苯醌(简称C18-TCNQ)在Lang-muir-Blodgett(LB)膜中的电荷转移。实验结果表明,在交替和混合LB膜中,酞菁铜和C18-TC-NQ分子之间均发生了电荷转移,其中酞菁铜为给体分子,TCNQ为受体分子。在混合LB膜中,电荷转移程度较大。电导率测量表明荷移反应使LB膜的电导率较纯酞菁铜LB膜提高了3个数量级。
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通过联苯二酚(介晶基元)、取代对苯二酚(破坏结晶基元)与4,4′-二氟二苯酮的亲核取代反应合成了一系列具有液晶性的新型聚芳醚酮.采用DSC、PLM和WAXD等方法对聚合物的研究表明:联苯含量为70%时聚合物表现为向列相,联苯含量为50%时聚合物出现近晶相.在外力场作用下,向列相液晶容易形成明暗交替的条带织构
Resumo:
A series of tensile and three-point bending studies was conducted at various temperatures and loading rates using phenolphthalein polyether ketone (PEK-C). Yield stress, Young's modulus, fracture toughness, and crack opening displacement data were obtained for various conditions. In general, both yield stress and Young's modulus increase with decreasing temperature. However, the relationships between fracture toughness, loading rate, and temperature are very complex. This behavior is due to the simultaneous intersection of viscoelasticity and localized plastic deformation. The increased yield stress is the main factor contributing to the reduction in fracture toughness and crack opening displacement. The relationship between fracture toughness and yield stress are discussed. (C) 1995 John Wiley and Sons, Inc.
Resumo:
A 700-year record (1.0-1.5 a resolution) of the East Asian winter monsoon (EAWM), based on grain-size analysis and AMS(14)C dating of Core EC2005 from the inner-shelf mud wedge of the East China Sea (ECS), was compared with the Dongge stalagmite delta O-18 record during the mid-Holocene. The upper muddy section of Core EC2005 has been formed mainly by suspended sediments derived from the Changjiang (Yangtze) River mouth since 7.3 ka BP. High precipitation and a strengthened EAWM might have played key roles in the high sedimentation rate (1 324-1 986 cm/ka) between 5.9-5.2 ka BP. The EAWM strengthened when the Asian summer monsoon weakened, especially around 5 500 a BP, which corresponded to a worldwide cold event. The EAWM during the mid-Holocene shows statistically significant solar periodicities at 62 and 11 a. The 5 500 a BP cold event might be resulted from orbital forcing and changes in solar activity.
Resumo:
角叉菜(Chondrus)是一种重要的经济红藻,广泛应用于食品行业及卡拉胶的提取工业。从种苗繁育的角度看,对角叉菜早期发育的研究意义重大。自然环境下角叉菜的生活史循环已得到阐释,但对其四分孢子及果孢子在室内条件下的早期发育过程还远远了解不够,因此有必要对其早期发育的具体特征和影响因素进行详细的分析研究。 本研究以青岛海域常见的角叉菜(Chondrus ocellatus Holm)作为实验材料,分析了实验室培养条件下温度及光强两个环境因子对其四分孢子和果孢子早期生长发育的影响,同时对整个发育过程进行了观察与记录。研究结果表明角叉菜两种孢子的早期生长发育过程基本一致,从孢子附着后萌发到长出幼苗,整个过程经历三个发育阶段:分裂期、盘状体期和直立幼苗形成期。另外,在早期发育过程中观察到多个盘状体融合的现象,这种融合使得孢子幼苗对基质的附着更加稳固,有利于其生存。通过设定6个温度梯度(10℃、15℃、20℃、22℃、25℃、28℃)及2个不同光照强度(10、60 μmol photos m-2s-1)条件,确立了角叉菜果孢子及四分孢子最适培养温度为20℃,而最适光照强度为60 μmol photos m-2s-1。角叉菜四分孢子和果孢子的早期生长发育均显示出较宽的温度耐受范围(10-25℃),但在28℃的高温条件下,两种孢子均会逐渐褪色死亡。分别采用单因素方差分析和独立样本t检验两种统计学方法分析温度和光强的影响,发现温度、光强的变化对角叉菜盘状体生长均有显著性影响。高光照可促进两种孢子的生长与发育,而低温(10℃)则会抑制孢子的的生长与发育。
Resumo:
对采自草甸、灌丛和弃耕地3种类型栖息地共27个甘肃鼠兔草堆的研究结果表明,每个草堆干重在23.8~984.2 g之间,平均184.2 g,总计含有26种双子叶植物和一些禾本科单子叶植物.分析显示,草堆大小(食物重量)与栖息地植被类型无关.在贮存干草堆时,甘肃鼠兔对不同植物成分具有强烈的选择性,其中,单子叶植物和双子叶植物分别占总重量的8.06%和84.61%,与它们各自在栖息地中的生物量百分比51.76%和39.57%形成鲜明对照.甘肃鼠兔对植物种类的选择性在一定程度上受栖息地植被类型的影响,但最喜食的几种植物却基本不变,它们是美丽风毛菊、棘豆、麻花艽、禾草、线叶龙胆.人工去除栖息地中的干草堆后,甘肃鼠兔种群越冬存活率从对照样地的51.84%下降到21.33%,表明草堆食物对其成功越冬有一定正效应.野外观察证实,甘肃鼠兔的鸣声不及同域分布的高原鼠兔发达,但前者具有贮存食物越冬的习性,而后者却不贮存越冬食物,此结果不支持"鼠兔类动物建立草堆的行为与鸣声行为平行发育"的观点.
Resumo:
对高原602双胚苗的细胞学进行了研究,有3种类型:2n-2n、2n-3n和2n-n,出现频率分别为0.16%、0.02%和0.02%。在2n-2n型里,又发现了形态上的差异,即2n(顶芒)-2n(长芒)。对单倍体育种和三倍体的起源进行了讨论。
Resumo:
Aiming at the character of Bohaii Sea area and the heterogeneity of fluvial facies reservoir, litho-geophysics experiments and integrated research of geophysical technologies are carried out. To deal with practical problems in oil fields of Bohai area, such as QHD32-6, Southern BZ25-1 and NP35-2 et al., technology of reservoir description based on seismic data and reservoir geophysical methods is built. In this dissertation, three points are emphasized: ①the integration of multidiscipline; ②the application of new methods and technologies; ③the integration of quiescent and dynamic data. At last, research of geology modeling and reservoir numerical simulation based on geophysical data are integrated. There are several innovative results and conclusion in this dissertation: (1)To deal with problems in shallow sea area where seismic data is the key data, a set of technologies for fine reservoir description based on seismic data in Bohai Sea area are built. All these technologies, including technologies of stratigraphic classification, sedimentary facies identification, structure fine characterization, reservoir description, fluid recognition and integration of geological modeling& reservoir numerical simulation, play an important role in the hydrocarbon exploration and development. In the research of lithology and hydrocarbon-bearing condition, petrophysical experiment is carried out. Outdoors inspection and experiment test data are integrated in seismic forward modeling& inversion research. Through the research, the seismic reflection rules of fluid in porosity are generated. Based on all the above research, seismic data is used to classify rock association, identify sedimentary facies belts and recognition hydrocarbon-bearing condition of reservoir. In this research, the geological meaning of geophysical information is more clear and the ambiguity of geophysical information is efficiently reduced, so the reliability in hydrocarbon forecasting is improved. The methods of multi-scales are developed in microfacies research aiming at the condition of shallow sea area in Bohai Sea: ① make the transformation from seismic information to sedimentary facies reality by discriminant analysis; ②in research of planar sedimentary facies, make microfacies research on seismic scale by technologies integration of seismic multi-attributes analysis& optimization, strata slicing and seismic waveform classification; ③descript the sedimentary facies distribution on scales below seismic resolution with the method of stochastic modeling. In the research of geological modeling and reservoir numerical simulation, the way of bilateral iteration between modeling and numerical simulation is carried out in the geological model correction. This process include several steps: ①make seismic forward modeling based on the reservoir numerical simulation results and geological models; ②get trend residual of forward modeling and real seismic data; ③make dynamic correction of the model according to the above trend residual. The modern integration technology of reservoir fine description research in Bohai Sea area, which is developed in this dissertation, is successfully used in (1)the reserve volume evaluation and development research in BZ25-1 oil field and (2)the tracing while drilling research in QHD32-6 oil field. These application researches show wide application potential in hydrocarbon exploration and development research in other oil fields.
Resumo:
Paleointensity changes of geomagnetic field help us to understand the evolutionprocess of earth completely and provide further constraints for earth interior process and geodynamo model. Marine sediments are good carriers for relative paleointensity of geomagnetic field. But in most cases, deep sea sediments that conform with magnetic "uniformity" usually have low sedimentation rate about l-2cm/ka and lie under the Carbonate Compensate Depth with little carbonate content. Therefore, the number of relative paleointensity records with detailed oxygen stratigraphy is still rare. This thesis focus on four cores from east of Ryukyu Trench which have foraminiferal content of 5-30% and sedimentation rate of lOcm/ka and wish to get centennial -millennial changes of relative paleointensity.The sediments from east of Ryukyu Trench conform with magnetic "uniformity" and remanences of four cores all show single component with stable direction and faithfully record the magnetic field. The NRM301T1T/ARM and NRMsomT/ x are still affected by grain size and concentration changes although the sediments are "uniform" , indicating the uniformity might not enough for relative paleointensity. After renomalized by grain size parameter MDF, the intensities remove the effect of grain size changes to different degrees and show coherency in 1-1 Oka scale with results from ODP983/984. The characteristics of paleointensity of geomagnetic field arefrom 32-24kaBP, paleointensity of geomagnetic field is low;24-12kaBP, paleointensity of geomagnetic field is high and shows two peaks boundary with 19kaBP.3) 12-5.3ka, paleointensity is low. Then increase from 5,3kaBP until a small trough at 2.7kaBP, then increase till now.