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41.
《Journal of computational and graphical statistics》2013,22(2):299-319
Online auctions have been the subject of many empirical research efforts in the fields of economics and information systems. These research efforts are often based on analyzing data from Web sites such as eBay.com which provide public information about sequences of bids in closed auctions, typically in the form of tables on HTML pages. The existing literature on online auctions focuses on tools like summary statistics and more formal statistical methods such as regression models. However, there is a clear void in this growing body of literature in developing appropriate visualization tools. This is quite surprising, given that the sheer amount of data that can be found on sites such as eBay.com is overwhelming and can often not be displayed informatively using standard statistical graphics. In this article we introduce graphical methods for visualizing online auction data in ways that are informative and relevant to the types of research questions that are of interest. We start by using profile plots that reveal aspects of an auction such as bid values, bidding intensity, and bidder strategies. We then introduce the concept of statistical zooming (STAT-zoom) which can scale up to be used for visualizing large amounts of auctions. STAT-zoom adds the capability of looking at data summaries at various time scales interactively. Finally, we develop auction calendars and auction scene visualizations for viewing a set of many concurrent auctions. The different visualization methods are demonstrated using data on multiple auctions collected from eBay.com. 相似文献
42.
Sung Koo Kang Inhee Choi Jeongjin Lee Younghun Kim Jongheop Yi 《Current Applied Physics》2008,8(6):810-813
A variety of shapes, such as rod, tripod, -shape and cube, of Au nanocrystals were synthesized by employing different reaction conditions. The nanocrystals and their shape variation were characterized by transmission electron microscopy and UV–vis spectrophotometry. The evolution of shape was accomplished by controlling the parameters used in their synthesis, the concentration of reducing agent and surface capping agent. The effect of synthetic parameters on shape was explored, to determine suitable conditions for producing each shape of nanocrystals. Nanocrystals with different shapes have different plasmon bands in the visible region of the spectrum, which is a valuable property for sensor applications. 相似文献
43.
In the present paper, we investigate the convergence and the approximation order of the localized Szsz–Mirakjan operators, and obtain some new results to improve the results due to Omey [Note on operators of Szsz–Mirakjan type, J. Approx. Theory 47 (1986) 246–254]. 相似文献
44.
The stochastic nonlinear complementarity problem has been recently reformulated as an expected residual minimization problem which minimizes an expected residual function defined by an NCP function. In this work, we show that the expected residual function defined by the Fischer–Burmeister function is an function. 相似文献
45.
Sachiko Yoshihashi-Suzuki Izuru Sato Kunio Awazu 《International journal of mass spectrometry》2008,270(3):134-138
Matrix-assisted laser desorption and ionization by infrared laser (IR-MALDI) is expected to be an effective methods for soft-ionization of high-molecular weight proteins and intracellular proteins. IR-MALDI is not widely used because its low sensitivity, complexity, high cost, and as it does not work well on commercial MALDI time-of-flight mass spectrometers (TOFMSs). We employed a tunable mid-infrared (MIR) laser as a light source for MALDI to investigate the IR-MALDI. The laser wavelength can be tuned within a range from 5.5 to 10.0 μm, and included several biomaterial group vibration modes. We evaluated the wavelength dependence of ionization in IR-MALDI for four matrices: succinic acid, urea, 3,5-dimethoxy-4-hydroxycinnamic acid (sinapic acid) and 2,5-dihydroxybenzoic acid (DHB). These matrices contained various groups of vibration modes, and absorbed an infrared (IR) energy at a specific wavelength. The mass spectra of angiotensin II was obtained at a specific wavelength corresponding to the CO stretching and benzene ring vibration mode. In IR-MALDI, we considered the strong molecular bond attracting an electron from a neighboring hydrogen atom, possibly protonating the hydrogen atom. 相似文献
46.
Andrew Bakan 《Journal of Mathematical Analysis and Applications》2008,339(1):197-216
For the sets , 1?p<∞, of positive finite Borel measures μ on the real axis with the set of algebraic polynomials P dense in Lp(R,dμ), we establish a majorization principle of their “boundaries,” i.e. for every there exists such that dμ/dν?1. A corresponding principle holds for the sets , p>0, of non-negative upper semi-continuous on R functions (weights) w such that P is dense in the space : For every there exists such that w?ω. 相似文献
47.
Mingjin Wang 《Journal of Mathematical Analysis and Applications》2008,341(2):1487-1494
In this paper, we use the Andrews-Askey integral and the q-Chu-Vandermonde formula to derive a more general integral formula. Applications of the new integral formula are also given, which include to derive the q-Pfaff-Saalschütz formula and the terminating Sears's transformation formula. 相似文献
48.
Yusuf Nur Demet G. Colak Ioan Cianga Yusuf Yagci Jale Hacaloglu 《Polymer Degradation and Stability》2008,93(5):904-909
The thermal degradation characteristics of a new macromonomer poly(-caprolactone) with central 4,4′-dicarbaldehyde terphenyl moieties and poly(phenylene vinylene)s with well defined (-caprolactone), (PPV/PCL) as lateral substituents were investigated via direct pyrolysis mass spectrometry. The unexpectedly high thermal stability of the macromonomer was attributed to intermolecular acetylation of benzaldehyde yielding a hemiacetal and causing a crosslinked structure during the pyrolysis. Increased thermal stability of the PCL chains was detected for all samples. The increase in stability of PCL chains was much more pronounced than was detected for poly(p-phenylene)-graft-poly(-caprolactone) copolymer (PPP/PCL); the upward temperature shift was about 100 °C for PPV/PCL and only 20 °C for PPP/CL. This pronounced effect may be due to higher thermal stability of PPV compared to PPP and the decrease in steric hindrance for PPV with PCL side chains. 相似文献
49.
Kenji Uneyama 《Journal of fluorine chemistry》2008,129(7):550-576
Preparations, reactions, and synthetic applications of functionalized fluoroalkyl and alkenyl silanes have been summarized. This review focuses mainly on the chemistries of (1) 1-substituted difluoromethylsilanes (XCF2SiR3), (2) 1-substituted 2,2-difluorovinylsilanes (CF2CXSiR3), (3) trifluoroisopropenyl, trifluoroacetimidoyl, and trifluoroacetyl silanes [CF3C(SiR3)X, XCH2, NAr, O] and (4) other fluorinated alicyclic silanes. 相似文献
50.
Bin Li 《Journal of organometallic chemistry》2008,693(1):87-96
Reaction of the doubly bridged dinuclear molybdenum complex (Me2C)(Me2Si)[(η5-C5H3)Mo(CO)3]2 (1) with benzonitrile in refluxing xylene afforded complexes (Me2C)(Me2Si)[(η5-C5H3)2Mo2(CO)4(μ-η2-η2(⊥)-NCPh)] (2) (50%) and (Me2C)(Me2Si)[(η5-C5H3)2Mo2(CO)4(μ-η1-η2-NCPh)] (3) (6%) with different coordination of nitrile. The corresponding μ-η2-η2 acetonitrile and propionitrile complexes 4 and 5 could be obtained from the reactions of (Me2C)(Me2Si)(C5H4)2 with (RCN)3Mo(CO)3 (R = Me, Et) in refluxing xylene. Reactions of 1 with isonitriles generated μ-η1-η2-CNR (R = tBu, Ph, C6H11) bridged complexes 6-8 in 53-63% yields. Subsequent reaction of 4 with Ru3(CO)12 yielded two CN bond cleavaged MoRu clusters (Me2C)(Me2Si)(η5-C5H3)2Mo2Ru3(CO)10(μ-CO)(μ3-CMe)(μ4-N) (9) (7%) and [(Me2C)(Me2Si)(η5-C5H3)2]2Mo4Ru6(CO)16(μ-CO)(μ4-CO)2(μ3-η1-η2-η2-NCMe)(μ3-CMe)(μ5-N) (10) (8%). All the new complexes have been fully characterized. The molecular structures of 2, 4, 6, 9, and 10 have been determined by X-ray diffraction analysis. 相似文献