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Search Results: 1 - 10 of 127088 matches for " ZHANG Shao-ping "
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Free Radical Scavenging Activity and Characterization of Sesquiterpenoids in Four Species of Curcuma Using a TLC Bioautography Assay and GC-MS Analysis
Jing Zhao,Jiang-sheng Zhang,Bin Yang,Guang-Ping Lv,Shao-Ping Li
Molecules , 2010, DOI: 10.3390/molecules15117547
Abstract: The sesquiterpenoids are one of major groups of antioxidants in Curcuma besides curcuminoids. However, the real substances contributing to the antioxidant activity are still unknown. In this paper, the antioxidant activity of sesquiterpenoids in four species and two essential oils from Curcuma genus was determined and compared based on TLC separation and DPPH bioautography assay. Their antioxidant capacities were quantitatively evaluated using densitometry with detection at 530 nm (λreference = 800 nm) using vitamin C as reference. The results showed that Curcuma longa rhizomes had the highest antioxidant capacity while C. phaeocaulis presented the lowest one among the four species of Curcuma. Moreover, essential oil of C. wenyujin showed higher antioxidant potential than that of C. longa. The main TLC bands with antioxidant activity of the four species of Curcuma were collected and characterized using GC-MS, and thus curzerene, furanodiene, α-turmerone, β-turmerone and β-sesquiphellandrene were determined as major sesquiterpenoids with antioxidant activity in Curcuma.
Anomalous optical and electronic properties of dense sodium
Dafang Li,Hanyu Liu,Bao-Tian Wang,Hongliang Shi,Shao-Ping Zhu,Jun Yan,Ping Zhang
Physics , 2010, DOI: 10.1016/j.physleta.2010.08.079
Abstract: Based on ab initio density-functional-theory using generalized gradient approximation, we systematically study the optical and electronic properties of the insulating dense sodium phase (Na-hp4) reported recently [Ma \textit{et al.}, Nature \textbf{458}, 182 (2009)]. The structure is found optically anisotropic and transparent to visible light, which can be well interpreted using its electronic band structure and angular moment decomposed density of states. Through the bader analysis of Na-hp4 at different pressures, we conclude that ionicity exists in the structure and becomes stronger with increasing pressure. In addition, the absorption spectra in the energy range from 1.4 to 2.4 eV are compared with recent experimental results and found good agreement. It is found that the deep-lying valence electrons participate in the interband transition.
Isolation and Identification of Two New Polyynes from a North American Ethnic Medicinal Plant--Oplopanax horridus (Smith) Miq.
Wei-Hua Huang,Qing-Wen Zhang,Chong-Zhi Wang,Chun-Su Yuan,Shao-Ping Li
Molecules , 2010, DOI: 10.3390/molecules15021089
Abstract: Two new polyynes, named oplopantriol A (5) and oplopantriol B (6), were isolated from the root bark of Oplopanax horridus (Smith) Miq, an ethnic medicinal plant of North America, along with four known polyynes: (3S,8S)-falcarindiol (1), oplopandiol (2), (11S,16S,9Z)-9,17-octadecadiene-12,14-diyne-1,11,16-triol, 1-acetate (3) and oplopandiol acetate (4). The structures of the new compounds were elucidated by detailed spectroscopic analyses, including 1D and 2D NMR techniques and chemical methods. The absolute configurations of the new compounds 5 and 6 were determined by comparing their optical rotation values with the hydrolysis products of the known compounds 3 and 4, respectively, derived from the same plant. On the basis of an analysis of their physical and chemical properties we show that the alkaline hydrolysis of 3 and 4 afforded the new compounds 5 and 6, respectively.
Overview of Data Management in Wireless Sensor Networks

ZHANG Shao-ping,WANG Ying-hua,LI Guo-hui,

计算机科学 , 2010,
Abstract: Wireless sensor networks are data-centric networks in nature,they deal with continuous data streams collected by sensor nodes. Therefore, existing data management technologies view wireless sensor network as a distributed database system composed of continuous data streams which come from the physical world. Due to the limitations of Sensor nodes' computing power, storage capacity, communication capabilities and battery energy, combined with the characteristics of flash memory and data streams,these lead to some challenges that the traditional distributed database systems have not encountered for data managements.This paper introduced the database system architecture, data storage and index technologies, data models, and query processing and optimization technologies for wireless sensor networks.
An Image Retrieval Relevance Feedback Algorithm Based on the Bayesian Classifier

SU Zhong,ZHANG Hong-jiang,MA Shao-ping,

软件学报 , 2002,
Abstract: The biggest problem in content-based image retrieval (CBIR) is a big gap between high-level semantic contents and low-level features. As an effective solution, relevance feedback has been put on many efforts for the past few years. In this paper, a new relevance feedback approach with progressive learning capability is proposed. It is based on a Bayesian classifier and treats positive and negative feedback examples with different strategies. It can utilize previous users' feedback information to improve its retrieval ability. The experimental results show that this algorithm achieves high accuracy and effectiveness on real-world image collections.
DF or IDF? On the Use of Primary Feature Model for Web Information Retrieval

ZHANG Min,MA Shao-ping,SONG Rui-hua,

软件学报 , 2005,
Abstract: In Web information retrieval (IR), input queries are too short and fuzzy to describe user request, which leads to the mismatch problem between user query and the documents full of redundancy and noise. This paper first studies the feature of web documents information and proposes the concepts of primary feature word, primary feature field and primary feature space (PFS). Then a new PFS query term weighting scheme is proposed, which takes document frequency (DF) into account instead of the traditional IDF factor. Finally, a combination strategy of term weighting is given. Using this PFS model, three groups of experiments have been performed on 10G and 19G large scale Web collections with TREC9, TREC10 and TREC11 standard tests of Web tracks. Comparative studies indicate that the new DF-related PFS term weighting improves the system performance consistently and effectively in terms of recall, top n precision and mean average precision. At most 18.6% improvement has been made.
Web Key Resource Page Judgment Based on Improved Decision Tree Algorithm

LIU Yi-Qun,ZHANG Min,MA Shao-Ping,

软件学报 , 2005,
Abstract: Key resource page is one of the most important search target pages for Web search users. Decision tree learning is one of the most widely-used and practical methods for inductive inference in machine learning. Because of the difficulty in uniform sampling of Web pages, there are not enough negative instances for training a key resource decision tree. To solve the problem, the original algorithm is partly modified to learn from global instead of individual instance information. With the same evaluation method as TREC (Text Retrieval Conference) 2003, large scale retrieval experiments based on improved decision tree algorithm achieves more than 40% improvement than the ones based on the original algorithm. It not only offers an effective way for selecting Web key resource pages, but also shows a possible way to improve decision tree learning performances.
A new ignition scheme using hybrid indirect-direct drive for inertial confinement fusion
Zhengfeng Fan,Mo Chen,Zhensheng Dai,Hong-bo Cai,Shao-ping Zhu,W. Y. Zhang,X. T. He
Physics , 2013,
Abstract: A new hybrid indirect-direct-drive ignition scheme is proposed for inertial confinement fusion: a cryogenic capsule encased in a hohlraum is first compressed symmetrically by indirect-drive x-rays, and then accelerated and ignited by both direct-drive lasers and x-rays. A steady high-density plateau newly formed between the radiation and electron ablation fronts suppresses the rarefaction at the radiation ablation front and greatly enhances the drive pressure. Meanwhile, multiple shock reflections at the fuel/hot-spot interface are prevented during capsule deceleration. Thus rapid ignition and burn are realized. In comparison with the conventional indirect drive, the hybrid drive implodes the capsule with a higher velocity ($\sim4.3\times10^7$ cm/s) and a much lower convergence ratio ($\sim$25), and the growth of hydrodynamic instabilities is significantly reduced, especially at the fuel/hot-spot interface.
Distribution of endocrine-disrupting PCBs in hard roes of loaches and their potential ecological effects in Weishanhu Lake,China
Distribution of endocrine-disrupting PCBs in hard roes of loaches and their potential ecological effects in Weishanhu Lake, China

KUANG Shao-ping,

环境科学学报(英文版) , 2004,
Abstract: Preliminary study is carried out on the endocrine-disrupting organic chemicals of polychlorinated biphenyls( PCBs: PCB-28, 60, 104, 153, 190) in hard roes of loaches( Misgurnus anguillicaudatas) in Weishanhu Lake, China. Results showed that the hard roes of loaches collected from the areas near the influx(such as Pengkou T-PCB = 0.243 microg/g) or efflux(such as Hanzhuang T-PCB = 0.221 microg/g) are characterized by higher PCB contents, about 4 times that from the central lake(T-PCB = 0.066 microg/g), suggesting great difference between their pollutions. The PCB distributions indicated that PCB congeners with more chlorine are more easily accumulated in roes of loaches. The microscopic characteristics reveal that the PCB contents at present cannot lead the roes of loaches to be abnormal. However, the roes with higher PCBs in Pengkou and Hanzhuang are obviously bigger than those with lower PCBs(T-PCBs < or = 0.176 microg/g) in other localities. It is suggested that PCBs have a stronger estrogenic activity on the roes of loaches, and the phenomenon is likely premonitory for the abnormal development of the hard roes.
Influences of decoherence on the generation of a macroscopic superposition state using weak cross-Kerr effect

Wu Shao-Ping,

物理学报 , 2008,
Abstract: Considering a system in which a single photon and a coherent field propagate through a Kerr medium, when the weak cross-Kerr interaction between the coherent state and the single photon under decoherence is involved, this paper derives analytically a macroscopic superposition state by the superoperator method and investigates the influences of decoherence on the coherence properties of the obtained state. It finds that the macroscopic superposition state will experience evolution from a pure superposition state to a mixed state in a dissipative environment and the Kerr effect makes the field display a periodic revival from decoherence for a short time.
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