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441.
442.
Futures trading is the core of futures business, and it is considered as one of the typical complex systems. To investigate the complexity of futures trading, we employ the analytical method of complex networks. First, we use real trading records from the Shanghai Futures Exchange to construct futures trading networks, in which nodes are trading participants, and two nodes have a common edge if the two corresponding investors appear simultaneously in at least one trading record as a purchaser and a seller, respectively. Then, we conduct a comprehensive statistical analysis on the constructed futures trading networks. Empirical results show that the futures trading networks exhibit features such as scale-free behavior with interesting odd-even-degree divergence in low-degree regions, small-world effect, hierarchical organization, power-law betweenness distribution, disassortative mixing, and shrinkage of both the average path length and the diameter as network size increases. To the best of our knowledge, this is the first work that uses real data to study futures trading networks, and we argue that the research results can shed light on the nature of real futures business. 相似文献
443.
In this paper, we investigate the epidemic spreading for the SIR model in weighted scale-free networks with the nonlinear infectivity and weighted transmission rate. Concretely, we introduce the infectivity exponent α and the weight exponent β into the epidemic system, then examine the impact of α and β on the epidemic spreading. We show that one can adjust the values of α and β to rebuild a nonzero finite epidemic threshold. Furthermore, we also find the infectivity exponent α has a stronger effect not only on the epidemic threshold, but also on the epidemic prevalence. In addition, it is also interesting to see that the absence of the epidemic threshold appears not very dejected, since the prevalence grows much more slowly as the transmission rate λ increases. 相似文献
444.
This article proves the logarithmically improved Serrin's criterion for solutions of the 3D generalized magneto-hydrodynamic equations in terms of the gradient of the velocity field, which can be regarded as improvement of results in [10] (Luo Y W. On the regularity of generalized MHD equations. J Math Anal Appl, 2010, 365: 806–808) and [18] (Zhang Z J. Remarks on the regularity criteria for generalized MHD equations. J Math Anal Appl, 2011, 375: 799–802). 相似文献
445.
446.
以高岭土为载体、钨粉为催化剂前驱物,过氧钨酸为催化剂活性组分,经催化H2O2-环己酮的反应合成了己二酸.利用反应过程中催化活性组分在高岭土表面的选择性吸附,在反应完成后分离出负载过氧钨酸的高岭土并重复循环使用,考察了反应条件对己二酸收率的影响,并测定了过氧钨酸-高岭土的重复使用性能.采用红外光谱分析了高岭土及循环使用的过氧钨酸-高岭土的化学结构.结果表明,载体高岭土能够在反应过程中有效负载过氧钨酸,并且过氧钨酸-高岭土第4次循环利用后其产物的收率基本不随重复利用次数增加而发生变化. 相似文献
447.
Pengwei Li Jihong Chen Weisheng Feng Xianling Wang 《Journal of the Iranian Chemical Society》2014,11(3):741-749
In this work, the CO2 and N2 adsorption properties of MIL-101 metal-organic framework (MOF) and activated carbon (AC) were investigated using a standard gravimetric method within the pressure range of 0–30 bar and at four different temperatures (298, 308, 318 and 328 K). The dual-site Langmuir–Freundlich (DSLF) model was used to describe the CO2 adsorption behaviors on these two adsorbents. The diffusion coefficients and activation energy E a for diffusion of CO2 in the MIL-101 and AC samples were estimated separately. Results showed that the isosteric heat of CO2 adsorption on the MIL-101 at zero loading was much higher than that on the AC due to a much stronger interaction between CO2 molecule and the unsaturated metal sites Cr3+ on MIL-101. Meanwhile, the dramatically decreased isosteric heats of CO2 adsorption on MIL-101 indicated a more heterogeneous surface of MIL-101. Furthermore, the adsorption kinetic behaviors of CO2 on the two samples can be well described by the micropore diffusion model. With the increase of temperature, the diffusion coefficients of CO2 in the two samples both increased. The activation energy E a for diffusion of CO2 in MIL-101 was slightly lower than that in AC, suggesting that MIL-101 was much favorable for the CO2 adsorption. The CO2/N2 selectivities on MIL-101 and AC were separately estimated to be 13.7 and 9.2 using Henry law constant, which were much higher than those on other MOFs. 相似文献
448.
电站锅炉的烟气脱硝过程同其他电站热工过程一样存在一定迟延性和惯性。本文根据目前烟气脱硝系统运行情况,总结分析了氮氧化物(NOX)排放控制过程的特点、影响因素以及控制系统。为解决锅炉运行过程中系统呈现出的大迟延和大惯性问题对整个烟气脱硝控制品质产生的影响,以及实现系统的稳定性和快速性,在原有的串级回路系统中,加入了Smith预估补偿控制器提前预估系统的动态特性并对其进行补偿。根据烟气脱硝系统对象的传递函数,设计了Smith预估补偿控制系统,采用Matlab中的Simulink对控制系统的对象和改进前后的控制系统响应曲线进行仿真分析,可以看出改进后系统动态品质变好,系统的快速性和稳定性也明显提高。 相似文献
449.
Two divalent-metal-containing aluminophosphates, (C(5)H(14)N(2))[Co(2)Al(4)P(6)O(24)] and (C(5)H(14)N(2))[Zn(2)Al(4)P(6)O(24)] (denoted as MAPO-CJ62; M = Co, Zn), have been hydrothermally synthesized by using N-methylpiperazine as the structure directing agent. Their structures are determined by single crystal X-ray diffraction and further characterized by powder X-ray diffraction, inductively coupled plasma, and thermogravimetric and diffuse reflectance spectroscopy analyses. Both of these two compounds exhibit a new zeolite framework topology. This new zeolite framework contains 1-dimensional 8-ring channels running along the [010] direction. All the metal and P atoms are tetrahedrally coordinated and alternately connected to each other through bridging O atoms. Inductively coupled plasma analysis shows that the molar ratio of M:Al in MAPO-CJ62 is 1:2. The M(2+) ions in MAPO-CJ62 selectively occupy two of the three possible crystallographically distinct positions. A pure aluminophosphate analogue of MAPO-CJ62 without M(2+)-incorporation, denoted as AlPO-CJ62, has not been obtained in our experiment so far. The necessity of introducing M(2+) ions and their ordered distribution in MAPO-CJ62 has been elucidated by analyzing the distortions of Al-centered tetrahedra in the hypothetical framework of AlPO-CJ62. 相似文献
450.
Yan Z Lu L Shi J Bao C Han W Wu Y Zhang Y 《Applied biochemistry and biotechnology》2006,133(2):149-162
Interferon-α2a (IFN-α2a) has been used for the treatment of various viral infections and cancers for many years. However some
untolerable side effects have limited its application in some aspects. To evaluate whether or not an oligopeptide containing
GFE motif can home human IFN-α2a to specific tissues, a fusion gene was constructed by fusing the coding sequence of GFE peptide
(CGFECVRQCPERC), which was screened from phage display peptide library, to the 3′ end of human IFN-α2a gene by recombinant
DNA technique. Fusion protein rhIFN-α2a-GFE was expressed in Escherichia coli as inclusion bodies using a T7 RNA polymerase expression system, pET-22b, refolded through dialysis and purified to homogeneity
to >95% of purity by affinity chromatography. Characterization by sodium dodecyl sulfate polyacrylamide gel electrophoresis
and immunoblotting demonstrated the authenticity of the fusion protein. Purified rhIFN-α2a-GFE was found to be functionally
active in terms of its antiviral activity for about 2.5×108 IU/mg in vitro. Yields of the purified fusion protein were about 200 mg/L of culture medium. Tissue distribution assay in
mouse showed that at 30 min IFN-α2a could be enriched sevenfold higher in lung in the targeted IFN group of mice than in the
standard IFN group of mice, and last for a long time. At 1 h, IFN-α2a in the targeted IFN group was still 4.02-fold higher
than that in the standard group. This confirmed that GFE peptide has the ability to selectively deliver its fusion partner
IFN-α2a to lungs. The results also showed that the IFN-α2a-GFE could be specifically enriched in kidney and liver. Its distribution
in kidney was concordant with the finding of GFE receptor, MDP, in kidney. However, the IFN-α2a-GFE in liver may imply some
significance in pharmacology and toxicology. 相似文献