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Search Results: 1 - 10 of 104743 matches for " Weiwei Zhang "
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The Assessment of Ice-snow Tourism Resources Value and Its Realization Degree  [PDF]
Weiwei Wu, Yexin Zhu, Chunyan Zhang
iBusiness (IB) , 2013, DOI: 10.4236/ib.2013.53B007

The development of the ice-snow tourism needs a scientific and effective method to assess the value of ice-snow tourism resource and its realization degree effectively and reasonability. Based on the analysis of expectation value and realization value of ice-snow tourism resource, this paper designs a three-dimension assessment index system and constructs the method of assessing the value of ice-snow tourism resource and its realization degree. Finally using ISW scenic area in Heilongjiang Province as an example for empirical analysis, the results show that the method can be effective in assessing the value of ice-snow tourism resource and its realization degree.

The Bone Microenvironmental Effect in the Dormancy of Cancer  [PDF]
Weiwei Shen, Yujie Niu, Helong Zhang
Journal of Cancer Therapy (JCT) , 2014, DOI: 10.4236/jct.2014.54038

Tumors have already threatened human life and health for centuries, especially the recurrent of bone metastases is difficult to cure. Relapse can occur years to decades after resection of primary tumor. This phenomenon is common in many clinical cases and animal experimental studies. The effect of traditional radiotherapy and chemotherapy on relapse is very limited, and the patients’ prognosis is poor. Because the delayed occurrence of metastases, researchers put forward a new concept “dormancy”, including a single dormant tumor cell (growth-arrest) and tumor mass dormancy (equivalence of the proliferation rate and apoptosis rate). It is probable that dormant tumor cells are the resource of relapse and the main reason of chemotherapy resistance. The mechanisms mediated tumor cell dormancy are complex and poorly understood, and bone marrow microenvironment plays an important role in this process. This review focuses on the bone marrow microenvironmental effect in inducing cancer cells to dormancy uncovered by the latest researches.

A Simple Strategy for Capturing the Unstable Steady Solution of an Unsteady Flow  [PDF]
Weiwei Zhang, Yilang Liu, Jing Li
Open Journal of Fluid Dynamics (OJFD) , 2015, DOI: 10.4236/ojfd.2015.52021
Abstract: A simple strategy for capturing unstable steady solution is proposed in this paper. By enlarging the real time step, the unstable high frequency modes of the unsteady flow can be effectively suppressed because of the damping action on the real time level. The steady component will not be changed during real time marching. When the unsteady flow solution converges to a steady state, the partial derivatives of real time in unsteady governing equations will disappear automatically. The steady solution is the exacted unstable steady solution. The method is validated by the laminar flow past a circular cylinder and a transonic buffet of NACA0012 airfoil. This approach can acquire high-precision unstable steady solutions quickly and effectively without reducing the spatial discretization accuracy. This work provides the basis for unstable flow modeling and analysis.
Robust Stochastic Stability Analysis for Uncertain Neutral-Type Delayed Neural Networks Driven by Wiener Process
Weiwei Zhang,Linshan Wang
Journal of Applied Mathematics , 2012, DOI: 10.1155/2012/829594
Abstract: The robust stochastic stability for a class of uncertain neutral-type delayed neural networks driven by Wiener process is investigated. By utilizing the Lyapunov-Krasovskii functional and inequality technique, some sufficient criteria are presented in terms of linear matrix inequality (LMI) to ensure the stability of the system. A numerical example is given to illustrate the applicability of the result.
Development of Actively Managed Exchange Traded Funds and the Revelation to Chinese Financial Market
Haiyong Ma,Weiwei Zhang
International Journal of Financial Research , 2010, DOI: 10.5430/ijfr.v1n1p55
Abstract: In recent years, the mutual funds market grown very fast, as an innovation of ETF product, the actively management ETF has drawn so much attention. In this article, we will analysis the difference between actively management ETF and traditional mutual funds/ETF, and its current situation and challenges faced in the future. At the end of this article, the authors discussed the trends of actively managed ETF and give several advices according the actual situation of Chinese financial market.
Research on the Undergraduate Financial Engineering Education in China
Haiyong Ma,Weiwei Zhang
World Journal of Education , 2011, DOI: 10.5430/wje.v1n2p69
Abstract: The rapid development of modern economy has put forward higher requirements for financial engineering education. This paper analyzes the status and problems in undergraduate financial engineering education in china, such as indistinct training objective, rigid curriculum structure, and superficial teaching methods, etc. and puts forward suggestions to improve undergraduate financial engineering education in China.
Brief Analysis of the Issue of Cross Border Merger and Acquisition in BRICs
Haiyong Ma,Weiwei Zhang
Research in World Economy , 2010, DOI: 10.5430/rwe.v1n1p43
Abstract: Based on the theory of cross-border M&A and the general law of development of international economics, this article analysis the overall trends of BRICs' oversea M&A activity. At the end of this article, the authors summarized the challenges faced by the enterprises of BRICs and give several advices according the actual situation of China.
The Effects of Target Skeletal Muscle Cells on Dorsal Root Ganglion Neuronal Outgrowth and Migration In Vitro
Weiwei Zhang, Zhenzhong Li
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0052849
Abstract: Targets of neuronal innervations play a vital role in regulating the survival and differentiation of innervating neurotrophin-responsive neurons. During development, neurons extend axons to their targets, and then their survival become dependent on the trophic substances secreted by their target cells. Sensory endings were present on myoblasts, myotubes, and myofibers in all intrafusal bundles regardless of age. The interdependence of sensory neurons and skeletal muscle (SKM) cells during both embryonic development and the maintenance of the mature functional state has not been fully understood. In the present study, neuromuscular cocultures of organotypic dorsal root ganglion (DRG) explants and dissociate SKM cells were established. Using this culture system, the morphological relationship between DRG neurons and SKM cells, neurites growth and neuronal migration were investigated. The migrating neurons were determined by fluorescent labeling of microtubule-associated protein-2 (MAP-2) and neurofilament 200 (NF-200) or growth-associated protein 43 (GAP-43). The expression of NF-200 and GAP-43 and their mRNAs was evaluated by Western blot assay and real time-PCR analysis. The results reveal that DRG explants showed more dense neurites outgrowth in neuromuscular cocultures as compared with that in the culture of DRG explants alone. The number of total migrating neurons (the MAP-2-expressing neurons) and the percentage NF-200-immunoreactive (IR) and GAP-43-IR neurons increased significantly in the presence of SKM cells. The levels of NF-200 and GAP-43 and their mRNAs increased significantly in neuromuscular cocultures as compared with that in the culture of DRG explants alone. These results suggested that target SKM cells play an important role in regulating neuronal protein synthesis, promoting neuritis outgrowth and neuronal migration of DRG explants in vitro. These results not only provide new clues for a better understanding of the association of SKM cells with DRG sensory neurons during development, they may also have implications for axonal regeneration after nerve injury.
Improvement in Structural and Magnetic Properties of Electrospun Ni1-xCuxFe2O4 Nanofibers  [PDF]
Weiwei Pan, Xinlei Zhang, Qin-Fang Liu, Jianbo Wang
Soft Nanoscience Letters (SNL) , 2017, DOI: 10.4236/snl.2017.72002
A series of Ni1-xCuxFe2O4 (0.0 ≤ x ≤ 1.0) nanofibers have been synthesized employing electrospinning method at 650°C. The effect of Cu substitution on structural, morphology and magnetic properties of NiFe2O4 nanofibers is reported. The XRD analysis showed the formation of single-phase cubic spinel Ni-Cu ferrite and an increasing behavior of lattice constant. The surface morphology is characterized by SEM, it is investigated that nanofibers have uniform and continuous morphology. The VSM results showed Cu substitution played an important role in magnetic properties of Ni1-xCuxFe2O4. The saturation magnetization (Ms) decreases linearly with increasing Cu2+ content, while coercivity (Hc) has slowly decreased before x ≤ 0.5, and then sharply increased to 723.9 Oe for x = 1.0. The magnetic properties of Ni1-xCuxFe2O4 can be explained in Neel’s model, cation distribution and shape anisotropy.
Isolation and Phylogenetic Analysis of Chromium(VI) Reducing Bacteria of a Magnetite Mine Drainage from Hebei China
Zhitang Lu,Xiufang An,Weiwei Zhang
Modern Applied Science , 2011, DOI: 10.5539/mas.v5n2p113
Abstract: A magnetite mine drainage sample collected from Han-Xing Iron mine area in Hebei Province was domesticated with potassium dichromate. Four kinds of media supplemented with 300mg/L chromium(VI) were used to isolate chromium(VI) tolerant bacteria. 10 Cr(VI) reducing strains which can tolerant at least 350 mg/L Cr(VI) and reduce the Cr(VI) efficently are screened by observing the growth station and measuring the remaining chromium (VI) concentration in media. 16S rDNA sequencing and phylogenetic analysis showed that Brevundimonas spp. are the main group of chromium(VI) tolerant bacteria in the magnetite mine drainage water sample.
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