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和“property”相关的论文

  • 经Opuntia dilenii haw植物提取液绿色合成制备的纳米铝酸锌的催化性质(英文) 相关:Green synthesis ZINC
  • Various nanosized zinc aluminate(ZnAl2O4) samples were prepared by a conventional and a mi- crowave method both with and without using Opuntia dilenii haw plant extract,and were charac- terized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),high resolution scanning electron microscopy(HRSEM),energy dispersion scanning(EDX),temperature dependent conductance measurements, thermoelectric power measurements, ultraviolet-visible (UV-Vis) diffuse reflectance spectroscopy,and photoluminescence spectroscopy.The formation of a pure ZnAl2O4 phase was confirmed by XRD and FT-IR.A change in morphology from nanosized plates to nanosized sheets with,respectively,the conventional and microwave heating methods was clearly shown by HRSEM.UV-Vis diffusion reflectance spectroscopy measured the band gaps of ZnAl2O4 nanosized plates and nanosized sheets as 3.5 and 3.9 eV,respectively.The synthesized ZnAl2O4 was single crystalline and has three photoluminescence emissions at 482,528,and 540 nm.ZnAl2O4 nanosized sheets prepared by the microwave method showed higher catalytic activity for the oxida- tion of benzyl alcohol(85% conversion) than ZnAl2O4 nanosized plates prepared by the convention- al method(60% conversion).
  • 非晶态金属-磷酸铝催化正庚醛和苯甲醛羟醛缩合制茉莉醛(英文) 相关:Amorphous aluminophosphate Metal-aluminoposphate
  • Amorphous aluminophosphate(AlP) and metal-aluminophosphates(MAlPs, where M = 2.5 mol%Cu, Zn, Cr, Fe, Ce, or Zr) were prepared by coprecipitation method. Their surface properties and catalytic activity for the synthesis of jasminaldehyde through the aldol condensation of nheptanal and benzaldehyde were investigated. The nitrogen adsorption-desorption isotherms showed that the microporosity exhibited by the aluminophosphate was changed to a mesoporous and macroporous structure which depended on the metal incorporated, with a concomitant change in the surface area. Temperature-programmed desorption of NHand COrevealed that the materials possessed both acidic and basic sites. The acidic strength of the material was either increased or decreased depending on the nature of the metal. The basicity was increased compared to AlP. All the materials were X-ray amorphous and powder X-ray diffraction studies indicated the absence of metal oxide phases. The Fourier transform infrared analysis confirmed the presence of phosphate groups and also the absence of any M-O moieties in the materials. The selected organic reaction occurred only in the presence of the AlP and MAlPs. The selectivity for the jasminaldehyde product was up to 75% with a yield of 65%. The best conversion of nheptanal with a high selectivity to jasminaldehyde was obtained with FeAlP as the catalyst, and this material was characterized to have less weak acid sites and more basic sites.
  • Synthesis, Crystal Structure and Catalytic Properties of a New 2D Nickel(II) Coordination Polymer Based on Flexible Bis(benzimidazole) 相关:bis(benzimidazole) CATALYTIC Property
  • A new Ni(II) coordination polymer [Ni(L)2(SCN)2]n(L = 1,4-bis(benzimidazol-1-yl)butane) was synthesized hydrothermally and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. The title compound crystallizes in the monoclinic system, space group C2/c with a = 9.4760(3), b = 24.0408(8), c = 16.5871(5) A, β = 99.832(3)°, V = 3723.2(2) A3, Z = 4, Dc = 1.348 g/cm3, F(000) = 1576, the final R = 0.0486 and w R = 0.0936 for 2938 observed reflections with I > 2σ(I) for the complex. Structural analysis shows that the coordination polymer possesses a 2D(4,4) layer structure which is composed of Ni(II) centers bridged by L ligand with two kinds of conformations and further assembled into a 3D supramolecular network via π-π stacking interactions. In addition, the fluorescence and catalytic properties, for the degradation of Congo red, of the complex were investigated.
  • Synthesis, Structure and Property of a Novel Coordination Polymer [Tb(C7H3NO4)(C6H4NO2)(H2O)] 相关:pyridine-2 5-dicarboxylic ACID
  • A novel terbium(III) coordination polymer [Tb(C7H3NO4)(C6H4NO2)(H2O)] was successfully synthesized hydrothermally and characterized by single-crystal X-ray diffraction. The complex is of monoclinic, space group P21/c with a = 9.2252(11), b = 14.1477(16), c = 10.5134(12) A, β = 95.770(2)°, V = 1365.2(3) A3, Z = 4, Dc = 2.248 g·cm-3, F(000) = 880, the final R = 0.0176 and w R = 0.0411 for 2149 observed reflections with I > 2σ(I). The complex is extended into a three-dimensional network structure with 24-atom rings which are composed of Tb, C and O atoms. The complex displays green fluorescence emission in the solid state at room temperature, which corresponds to 5D4 → 7F5 transition of the Tb(III) ion.
  • 多元回归中选择自变量的一种简单方法 相关:变量选择 回归分析 ORACLE
  • 在线性回归模型建模中,回归自变量选择是一个受到广泛关注、文献众多,具有很强的理论和实际意义的问题.回归白变量选择子集的相合性是其中一个重要问题,如果某种自变量选择方法选择的子集在样本量趋于无穷时是相合的,而且预测均方误差较小,则这种方法是可取的.利用BIC准则可以挑选相合的自变量子集,但是在自变量个数很多时计算量过大;适应lasso方法具有较高计算效率,也能找到相合的自变量子集;本文提出一种更简单的自变量选择方法,只需要计算两次普通线性回归:第一次进行全集回归,得到全集的回归系数估计,然后利用这些回归系数估计挑选子集,然后只要在挑选的自变量子集上再进行一次普通线性回归就得到了回归结果.
  • Some Ecological Properties of Pistacia atlantica Desf. in Khojir National Park of Iran 相关:PISTACIA atlantica Khojir
  • Khojir national park is one of the oldest protected areas in Iran that is greatly considerable in terms of biodiversity and ecological values.Pistachio(Pistacia atlantica Desf.) communities,which create some woodland in this park,are unique because they grow tolerantly in a dry land,in the vicinity of Tehran capital.This research is about some ecological properties of Pistachio woodlands.The dominant community of the area is Pistacia-Amygdalus lycioides.The density of Pistacia is 86 per hectare.The density of Pistachio trees was greater in the higher elevation than in the lower one.In addition,the collar diameter and the height of trees in the higher class were less.The average density of Pistacia in plots in northern slopes was significantly more than southern slopes(at 5% level),but the average collar diameter of them were more on the southern aspect.The distribution,diameter and height of pistachio trees were not significantly related to the percentage of slope.Among the soil variables,the saturated water percentage(SP),N(total nitrogen) and texture of soil were effective factors which played significant role in ordination of plots containing pistachio.Considering the important role of P.atlantica forest stands in soil and water conservation in Iran,we should attach more importance to their protection and conservation,as well as activities such as road and dam construction,and garden establishment in such unique ecosystems.
  • Exif数据格式浅析及其读取应用 相关:图形文件 分析 EXIF
  • 照片中镶嵌着丰富的Exif信息,从中可提取出拍摄位置与时间等实用数据服务于我们的工作与生活。本文分析了Exif数据格式,介绍了其读取方法,总结了Exif信息提取算法。结合具体实例,进行测试验证,对日常手机定位精度情况进行了评估。最后,通过生产实践,验证Exif信息对于提高测绘与地理信息单位的作业效率与质量控制的促进作用,同时对应用前景进行了展望。
  • Factors Affecting Sensory Quality of Cooked japonica Rice 相关:SENSORY quality PHYSICOCHEMICAL
  • The sensory quality of cooked rice is an important factor in determining its market price,as well as consumer acceptance and breeding efforts aimed at improvement of rice grain quality.In this study,the sensory quality and physicochemical properties of three japonica rice varieties harvested in two different growing locations(Xiangshui and Hangzhou of China)were compared to determine the most important factors affecting the sensory quality.All the three varieties had higher scores for overall sensory quality in Xiangshui than in Hangzhou,indicating that the growing location is a key factor in determining the sensory quality of cooked japonica rice.In addition to growing location,variety(genotype)also had an important effect.Longdao 18 scored the highest for overall sensory quality in the two locations,whereas Longdao 30 had the lowest score in Xiangshui,and both Longdao 20 and Longdao 30 had the lowest scores in Hangzhou.Many physicochemical properties,such as apparent amylose content,protein content,thermal properties and free amino acid contents,showed significant differences between the two locations.Correlation analysis showed that apparent amylose content and protein content had contrasting effects on all the sensory attributes.The overall sensory quality was negatively correlated with protein content(r=-0.89,P<0.01)and positively correlated with gel hardness(r=0.91,P<0.01),indicating that the protein content and hardness are important physicochemical properties for predicting the sensory quality of japonica rice.These findings will provide guidance for selection from the diverse genotypes available to develop new varieties with the desired eating and cooking quality.
  • Some Aspects of Physical-mechanical Properties of Apple (Malus domestica) Cultivars for High Techniques in Manufacturing 相关:APPLE HARVEST processing
  • Several mechanical and physical properties of five apple cultivars (Black, Apricot, Jester, Big Ariane and Medium Ariane) had been estimated. The results showed that there were important significant differences among the cultivars in most of the parameters that were measured. Among the cultivars, Black cultivar had the highest fruit mass (207.65 g), followed by Big Ariane (188.34 g) and Medium Ariane (137.49 g). The actual fruit volume (cm3) ranged from 61.77 (Apricot) to 269.67 (Black). The highest geometric, arithmetic, square and equivalent mean diameter values were observed for Big Ariane. The surface area and projected area of cultivars were between 14.53-69 cm2 and 45.56-165.33 cm2, respectively. The maximum coefficient of static friction was obtained on plastic followed by steel, iron and glass; the maximum coefficient of dynamic friction was obtained on glass followed by steel, plastic and iron.
  • Effects of laccase incubated from white rot fungi on the mechanical properties of fiberboard 相关:White ROT FUNGUS
  • White rot fungi were optimized to cultivate highly active laccase. The characteristics of laccase incubated by continuous culture were compared with those of direct culture. The enzyme activity of laccase incubated by continuous culture technology reached a higher value on the fifth day of the growth. The optimization incubation time of high activity laccase was the eleventh day. A large amount of highly active laccase can be obtained in a relatively short time by continuous culture to replace traditional laccase. After laccase treatment, the lignin composition of wood fibers were oxidation-catalyzed by laccase. The number of chemical-bonding points between the wood fibers was increased. The wood fibers treated by laccase were fabricated into boards and their mechanical properties improved with the laccase-incubation times.Compared with the fiberboards made from fibers that were pre-treated by laccase of incubation 5 days, the static bending strength of those that were pre-treated by laccase of incubation 11 days was increased by 18.95%, the elastic modulus was increased by 35.49%, and the internal bond strength was increased by 44.11%.