检索结果-南通市图书馆

Stereoselective cycloaddition of N-acyliminium cations withα,β-unsaturated ketones and esters

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2009年第7期20卷 805-808页

作者： Ling Feng Qian Yue hua zhou wei Zhang State Key Laboratory of Applied Organic Chemistry Lanzhou University Lanzhou 730000 China

The cycloaddition of N-acyliminium cations with some deactivated alkenes such as α,β-unsaturate ketones and esters has been investigated. In most cases, the N-acyliminium cations produced from 3-hydroxy-2-arylisoindol-1-ones in the presence of ***2 could be reacted with α,β-unsaturated ketones and esters to afford stereoselectively the cycloaddition products 6-acylisoindolo[2,1- a]quinolin-11-ones in moderate to high yields. C 2009 wei Zhang. Published by Elsevier B.V, on behalf of Chinese Chemical Society. All rights reserved.

关键词： Cycloaddition N-acyliminium cation 3-Hydroxy-2-arylisoindol- 1-one α,β-Unsaturated ketones 6-Acylisoindolo[2,1-a]quinolin- 11- ones

Demasking Multiple Artifact in Crustal Seismic Images from Marine Reflection Data in the Southern California Borderland

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2015年第4期26卷 592-597页

作者： Christopher Gantela Aifei Bian hua-wei zhou Tom Bjorklund Department of Earth & Atmospheric Sciences University of Houston Institute of Geophysics & Geomatics China University of Geosciences

Marine seismic reflection surveys are often masked by strong water-bottom multiples that limit the use of data beyond the first multiple waves. In this study, we have successfully suppressed much of the multiple artifacts in the depth images of two of the marine seismic reflection profiles from the Los Angeles regional seismic experiment （LARSE） by applying reverse time migration （RTM）. In contrast to most seismic reflection methods that use only primary reflections and diffractions, the two-way RTM migrates both primaries and multiple reflections to their places of origination： seabed multiples to the sea bottom and primaries to the reflecting interfaces. Based on the RTM depth sections of LARSE lines 1 and 2, we recognize five stratigraphic units from the sea bottom to a depth of 6 km. These units are Pliocene and younger strata, probably Miocene syntectonic strata, two deeper sequences of unknown age and lithology as well as Miocene volcanic layers on Catalina ridge. Several inferred igneous intrusions in the upper crust comprise a sixth unit. The existence of a thick sedimentary section in the Catalina Basin, which might include Paleogene and Cretaceous fore-arc strata, has important geologic significance. If borne out by further studies, significant revisions of current structural and stratigraphic interpretations of the California borderland would be warranted.

关键词： demasking multiple artifact reverse time migration LARSE Catalina schist,hydrocarbon basin.

Evaluation of Multi-Scale Full Waveform Inversion with Marine Vertical Cable Data

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2015年第4期26卷 481-486页

作者： Aifei Bian Zhihui Zou hua-wei zhou Jin Zhang Institute of Geophysics and Geomatics China University of Geosciences Department of Earth & Atmospheric Sciences University of Houston College of Marine Geosciences Ocean University of China

Seismic illumination plays an important role in subsurface imaging. A better image can be expected either through optimizing acquisition geometry or introducing more advanced seismic mi- gration and/or tomographic inversion methods involving illumination compensation. Vertical cable survey is a potential replacement of traditional marine seismic survey for its flexibility and data quality. Conventional vertical cable data processing requires separation of primaries and multiples before migration. We proposed to use multi-scale full waveform inversion （FWI） to improve illumination coverage of vertical cable survey. A deep water velocity model is built to test the capability of multi-scale FWI in detecting low velocity anomalies below seabed. Synthetic results show that multi-scale FWI is an effective model building tool in deep-water exploration. Geometry optimization through target ori- ented illumination analysis and multi-scale FWI may help to mitigate the risks of vertical cable survey. The combination of multi-scale FWI, low-frequency data and multi-vertical-cable acquisition system may provide both high resolution and high fidelity subsurface models.

关键词： full waveform inversion vertical cable illumination multi-scale geometry optimization,low-frequency data velocity model.

Enhancing Isolated Ti(Ⅳ) Framework Sites in HMS

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2007年第2期23卷 127-130页

作者： YU wei-hua zhou Chun-hui NI Zhe-ming GE Zhong-hua College of Chemical Engineering and Materials Science Zhejiang University of Technology Hangzhou 310024 P. R. China

Ti-HMS materials were prepared by grafting titanocene onto the inner wails of hexagonal mesoporous silica （HMS）. The materials were characterized via powder X-ray diffraction, N2 adsorption-desorption isotherms, diffuse reflectance UV-Vis spectroscopy, and thermo-gravimetric analysis. The template of HMS was removed by calcination, ethanol-extraction, and ethanol-extraction followed by hydrolysis. The available grafting sites of OH groups depend on the different template removal methods of HMS. Ethanol-extraction followed by hydrolysis favors site-isolated Ti atoms in HMS. The catalytic performances of Ti-HMS materials were tested in the oxidation of 4-tert-butyholuene with aqueous hydrogen peroxide. Ti-HMS prepared from HMS via the processing of ethanol-extraction followed by hydrolysis as support gave a maximum conversion of 7. 5% and a complete selectivity to 4-tert-butyl-benzaldehyde, and showed a higher activity compared with those prepared by calcination and ethanol-extraction.

关键词： Ti-HMS Grafting Oxidation 4-tert-Butyltoluene

An Evaluation of Reverse-Time Imaging of Clustering Earthquakes

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2015年第4期26卷 548-555页

作者： Zhihui Zou hua-wei zhou Aifei Bian Jianzhong Zhang Lei Xing College of Marine Geosciences Ocean University of China Department of Earth & Atmospheric Sciences University of Houston Institute of Geophysics and Geomatics China University of Geosciences

Clustering earthquakes refer to the seismic events that occur closely with each other in time and space. Because their overlapping waveform records make it difficult to pick the first arrivals, the hypocenters of clustering earthquakes cannot be determined accurately by traveltime location methods. Here we apply a reverse-time imaging （RTI） method to map clustering earthquakes. Taking the advantage of directly using waveforms, the RTI method is capable to map either a single small earthquake or some densely distributed clustering earthquakes beneath a 2-D seismic array. In 3-D case the RTI method is successfully applied to locate the long-offset doublet earthquakes using the data from a set of sparsely distributed surface stations. However, for the same acquisition geometry, the RTI encounters challenges in mapping densely distributed clustering earthquakes. While it is obvious that improving the mapping of clustering earthquakes requires a denser receiver network with wider range of illumination angles, it is necessary to verify the actual resolution of the RTI method with synthetic data. In our study area in the Three Gorges region, our tests in 3-D case suggest that some events beneath the linear aligned sub-arrays have reasonable resolution.

关键词： clustering earthquakes reverse-time imaging hypocentral location microseismie the Three Gorges.

Impact and Solutions of Seawater Heterogeneity on Wide-Angle Tomographic Inversion of Crustal Velocities in Deep Marine Environments—Numerical Studies

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2018年第6期29卷 1380-1389页

作者： Zhihui Zou hua-wei zhou Harold Gurrola Aifei Bian Zhonglai huang Jianzhong Zhang College of Marine Geosciences Key Lab of Submarine Geosciences and Prospecting Techniques MOEOcean University of China Evaluation and Detection Technology Laboratory of Marine Mineral Resources Qingdao National Laboratory for Marine Science and Technology Department of Earth & Atmospheric Sciences University of Houston Department of Geosciences Texas Tech University Institute of Geophysics and Geomatics China University of Geosciences

The seawater column is typically taken as a homogeneous velocity layer in wide-angle crustal seismic surveys in marine environments. However, heterogeneities in salinity and temperature throughout the seawater layer result insignificant lateral variations in its seismic velocity, especially in deep marine environments. Failure to compensate for these velocity inhomogeneities will introduce significant artifacts in constructing crustal velocity models using seismic tomography. In this study, we conduct numerical experiments to investigate the impact of heterogeneous seismic velocities in seawater on tomographic inversion for crustal velocity models. Experiments that include lateral variation in seawater velocity demonstrated that the modeled crustal velocities were contaminated by artifacts from tomographic inversions when assuming a homogeneous water layer. To suppress such artifacts, we propose two strategies：（1） simultaneous inversion of water velocities and the crustal velocities;（2） layer-stripping inversion during which to first invert for seawater velocity and then correct the travel times before inverting for crustal velocities. The layer-stripping inversion significantly improves the modeling of variation in seawater velocity when preformed with seismic sensors deployed on the ocean bottom and in the water column. Such strategies improve crustal modeling via wide-angle seismic surveys in deep-marine environment.

关键词： deep water seismic tomography wide-angle seismic survey water heterogeneity OBS vertical cable

Co,K-Supported Hexagonal Mesoporous Silicas for Catalytic Oxidation of 4-t-Butyltoluene

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2010年第4期26卷 622-625页

作者： YU wei-hua zhou Chun-hui TONG Dong-shen FANG Mei ZHANG Bo Research Group for Advanced Materials ＆ Sustainable Catalysis（AMSC） College of Chemical Engineering and Materials Science Zhejiang University of Technology Hangzhou 310014 P R. China

Co,K-Supported hexagonal mesoporous silicas（HMS） have been prepared by incipient wetness impregnation with cobalt acetate tetrahydrate and potassium acetate as metal precursors, and ethylene glycol as impregnation solvent. The products have been characterized via powder X-ray diffraction, N2 adsorption-desorption isotherms and diffuse reflectance UV-Vis spectroscopy. The divalent cobalt with a tetrahedral oxygen coordination exists mainly in the calcined samples. The catalytic properties have been tested for the oxidation of 4-t-butyltoluene with dioxygen in liquid phase at mild conditions. The products offered good catalytic activities in the oxidation reactions. Co-K-HMS catalyst with loading 4% Co and 2% K（mass fraction） affords a higher yield（22.4%） of 4-t-butylbenzaldehyde at a conversion of 28.3% under the reaction conditions. Adding a proper amount of potassium in Co-HMS results in an improvement catalytic activity and stability.

关键词： Mesoporous silica Catalyst Cobalt Potassium Oxidation

Interval attenuation estimation from prestack seismic data:A case study from the Arabian Peninsula

在线全文

学校读者我要写书评

暂无评论

Applied Geophysics 2020年第4期17卷 475-488页

作者： Abdullah Alshangiti hua-wei zhou University of Houston Department of Earth and Atmospheric SciencesHoustonTexasThe United States

Accurately estimated interval attenuation(1/Q)values have several applications,such as in quantitative interpretation and seismic resolution *** Q values can be estimated by measuring the spectral ratio between seismic reflections from a target and a reference reflector,the results are influenced by factors such as overburden ***,we quantitatively analyze the overburden influence on interval Q estimations using the spectral ratio method,time-space domain prestack Q inversion(PSQI),andτ-p domain *** compare these three methods using a synthetic dataset and a field dataset acquired onshore the Arabian *** seismic gathers are generated from a three-layer model with a low-Q inclusion in the first layer to mimic overburden *** fi eld data are preconditioned image gathers from a producing oil fi *** synthetic data test shows that the small low-Q body produces a considerable error in estimated Q *** smallest error(i.e.,13.3%)is in theτ-p domain PSQI ***,τ-p domain PSQI could obtain more accurate Q values when there are overburden infl uences because of the simultaneous inversion scheme and the application in theτ-p *** fi eld data application also illustrates that theτ-p domain PSQI produces reasonable interval Q *** measured Q values are also comparable with the Q values estimated from hydrocarbon saturated carbonate reservoirs.

关键词： Attenuation quality factor Q overburden inhomogeneity spectral ratio prestack Q inversion

Modification of Sugar Chains in Glycoalkaloids and Variation of Anticancer Activity

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2007年第3期23卷 303-309页

作者： LI Sheng-yu HE Da-jun ZHANG Xu NI wei-hua zhou Yi-fa ZHANG Li-ping School of Life Sciences Northeast Normal University Changchun 130024 P. R. China

To study the effect of the sugar chains in glycoalkaloids against cancer cells, 6-0-sulfated solamargine and acidcatalyzed hydrolytic products of α-solamargine and α-solasonine were prepared. The sulfation at 0-6 of solamargine was proceeded in five steps. The 6-OH group was first selectively protected with DMT-Cl, and then the secondary hydroxyl groups on the sugar ring were acetylated. After the protective group DMTr was removed, the free 6-OH group was sulfated. Finally, the acetyl groups were removed to give 6-0-sulfated solamargine in a good yield. The hydrolyses of solamargine and solasonine were performed in diluted hydrogen chlorede. Three and two hydrolyzed products were obtained from solamargine and solasonine, respectively. The antiproliferative activities against HCT-8 tumor cells of two glycoalkaloids and their derivaties were examined via a MTT assay. The results show that α-solamargine and α-solasonine exhibit strong cytotoxic activities with an IC50 of 10. 63 and 11.97 μmol/L, respectively, wheras their derivaties seem to be less activities.

关键词： Solamargine Solasonine Anticancer Sulfation Acidic hydrolysis