813 resultados para Research on problem solving


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The spectrum of highly ionized titanium was studied by means of the beam-foil technique. Titanium ions were provided by the HI-13 tandem accelerator at China Institute of Atomic Energy. The experimental results are compared with those of laser-produced plasmas. Numerous lines attributed to Ti XVI to XVIII ransitions have been identified, and three of them were newly measured, which were attributed to 2s2p(24)P(3/2)-2p(32)D(3/2), 2s2p(21)S(0)-2sp(31)P(1) and 4p(1)P(0)-5d(1)P(1) transitions.

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在类氢离子能级相对论修正的基础上,依据屏蔽方法,给出了类氟体系基态电离能的一种表达式.依据原子序数9至20的元素类氟体系基态电离能的实验数据,使用Microcal Origin软件拟合出类氟体系非电离电子平均屏蔽系数与原子序数的函数关系,总结出类氟体系基态电离能遵从的关系式并进行了验证.推算了原子序数21至40的元素类氟离子的基态电离能.

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选用12C6+离子辐照诱变阿维菌素B1a产生菌ZJAV-A1,研究其诱变效应。实验结果表明,12C6+离子辐照剂量50Gy时致死率97%,正突变率最高可达到34.2%。通过12C6+离子诱变处理,结合平板培养基及斜面培养基的正突变菌株筛选,最终获得一株稳定性良好,阿维菌素B1a组分产量稳定在4460—4588μg/ml之间,较出发菌株提高11.1%—14.7%的突变株ZJAV-Y1-203。

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973 Project of China [2006CB701305]; "863" Project of China [2009AA12Z148]; National Natural Science Foundation of China [40971224]

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Storage of raster metadata is a key topic in spatial database. Although there are a few of abstract standards on raster metadata, there is not implement standard about it. This paper concludes three storage models implemented in current spatial databases and discusses their advantages and disadvantages. After that analyzing, the paper proposes a mixed storage method which is used the relational table to store structured metadata and used XML to store non-structured metadata, and gives its implementation solution. © 2010 IEEE.

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Sodium polyacrylate was synthesized with acrylic acid as the monomer, and sodium bisulfate and ammonium persulfate as the initiator, by means of aqueous solution polymerization. The factors influencing the properties of moisture absorption, such as monomer concentration, dosage of initiator, and reaction temperature were systematically investigated. The experimental results indicate that the moisture-absorbing property of this polymer was better than other traditional material, such as silica gel, and molecular sieve. The best reaction condition and formula are based on the orthogonal experiment design. The optimum moisture absorbency of sodium polyacrylate reaches 1.01 g/g. The mathematical correlation of this polymer with various factors and moisture absorbency is obtained based on the multiple regression analysis. The moisture content intuitive analysis table shows that neutralization degree has the most significant influence on moisture absorbency, followed by monomer concentration and reaction temperature, while other factors have less influence.

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An asymmetric hydrophobic microporous membrane from the copolymer of tetrafluoroethylene and vinyliden fluoride (F2.4) has been fabricated by phase inversion process. Some characteristics, such as mechanical properties and hydrophobicity, have been examined and compared with polyvinylidenefluoride (PVDF) membrane. Experimental data exhibit F2.4 membrane excellent mechanical properties and hydrophobicity. F2.4 microporous membrane was approximately 6-8 times as high as PVDF membrane in stretching strain and extension ratio at break, and contact angle to distilled water of the fore (88.5degrees) was larger than the latter (80.0degrees), too. The results from membrane distillation (MD) process were well agreed with the fundamental laws of membrane distillation.

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Polypyrrole film electrode with Co(W2O7)(6)(10-) and CuW12O406- ions were synthesised in aqueous solutions, The electrode possesses a good stability and cyclic voltammetric behavior in weakly acidic or near neutral solutions, The redox of CuW12O406- ion can be catalysed by the polypyrrole film, The ESR measurement of the polypyrrole film with Co(W2O7)(6)(10-) and CuW12O406- ions indicates that the heteropolyanions not only play the role of neutralizing electricity in the polypyrrole film, contrasted with the film containing NO3-, but also Interact with the polypyrrole molecular chain to form some additive compound, The additive compound affects the electric structure elf the polypyrrole film and is unstable at more positive or more negative potentials.

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Irradiated polyamide-1010 (PA1010) and PA1010 containing 0.5% (wt) heterogeneous nuclei were studied by ESR, WAXD, DSC and the determination of gel fractions. The fold surface of the lamellae plays an important role in the effects of radiation on crystalline PA1010. The results show that the direct radiation effects on both samples vary, while after being heated to 220 degrees C, the final radiation effects are identical, regardless of the difference in the amount of the fold surface of the lamellae. The post-radiation effects result predominantly from the fold surface.

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The heteropolyanions of the Keggin structure ZW(11)O(39)M(H2O)(n-)(Z = Si, Ge, P; M = Ni2+, Cu2+, Cr3+, Co2+, n = 4 similar to 6) and Dawson structure P(2)W(17)O(61)M(H2O)(n-)(M = Ni2+, Cu2+, Cr3+, Co2+, n = 7, 8) have been transferred into the non-polar

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in this Raper, based on distance matrix and branch vertex of atomes in a molecule, a new topological index (Y(x)) has been developed to be used in research on physical and chemical properties of alkanes. It is concluded that this index bears good structure selectivity and relativity when the results from index were compared with that of other ones.

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Mossbauer spectroscopy has been used to investigate the thermal decomposition of the bioinorganic complex of europium and L-glutamine. The Mossbauer parameters can demonstrate that the water molecules in the complex and the chlorine anion in the hydrogen chloride molecule, dissociated from the complex below 200-degrees-C, are not linked directly to the europium atom. The thermal decomposition process of the complex is discussed and a possible coordination model for the europium L-glutamine complex is also proposed on the basis of the thermogravimetric and derivative thermogravimetric curves, and from some evidence obtained from the Mossbauer effects of some decomposition products of the complex.

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Antimicrobial peptides (AMPs) are important components of the host innate immune response against microbial invasion. They are usually characterized by their small-size, heat-stability and broad range of antimicrobial activity. This review covers research advances on marine mollusc AMPs, specifically those isolated from mussels, scallops, oysters, venerid clams and abalone, which mainly include MGD, mytilin, myticin, mytimycin, big defensin, and RPD-1. Their structural characteristics, antibacterial activity, and expression pattern as well as peptide distribution and their release following microbial challenge are also discussed. In addition, the prospect of the application of AMPs as food additives or their use in immunostimulation to prevent diseases of aquatic animals, as well as their potential hazards, are also discussed.

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A mass of geological, geophysical and geochemical data and information from the Okinawa Trough area are collected for comprehensive research in the study area from East China to Okinawa Trough and then to Ryukyu Island Are region. According to the seismic tomography result (P and S wave) and the processing result of free-air and Bouguer gravity anomaly and magnetic anomaly data in the study area, the comprehensive interpretation is carried out. The Moho depth distribution of the study area is obtained by the inversion calculation based on gravity data using the Harmonious Series method. The crust properties are analyzed. Meantime, some Cenozoic basalt data from Kuandian (NE China), Hannuoba (North China), Minxi (South China), Penghu Islands (Taiwan Strait), Okinawa Trough and Japan Island Arc regions are chosen to make the comparison research on element- isotopes. The result indicates that the lithosphere thickness in the Okinawa Trough area has obviously decreased, where a Low -velocity layer of upper-mantle has reached the Moho interface and the metasometized asthenosphere has formed. The research result on element- isotopes shows that the characteristic of the crust in the Okinawa Trough area is different from that in East China area and the Ryukyu Island Arc area. It is considered that the crust in the Okinawa Trough area belongs to the transition type, which is quite similar to the feature of the oceanic crust.