OALib Journal期刊

ISSN: 2333-9721




2018 ( 21 )

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2016 ( 37 )

2015 ( 333 )


匹配条件: “SHAO Nan” ,找到相关结果约12611条。
Spectral Softening in X-ray Afterglow of GRB 130925A as Predicted by Dust Scattering Model
Yi-Nan Zhao,Lang Shao
Physics , 2014, DOI: 10.1088/0004-637X/789/1/74
Abstract: Gamma-ray bursts (GRBs) usually occurs in a dense star-forming region with massive circum-burst medium. The small-angle scattering of intense prompt X-ray emission off the surrounding dust grains will have observable consequences, and sometimes can dominate the X-ray afterglow. In most of the previous studies, only Rayleigh-Gans (RG) approximation is employed for describing the scattering process, which works accurately for the typical size of grains (with radius $a\leq 0.1\,{\rm \mu m}$) in the diffuse interstellar medium. When the size of the grains may significantly increase as in a more dense region where GRBs would occur, the RG approximation may not be valid enough for modeling detailed observational data. In order to study the temporal and spectral properties of the scattered X-ray emission more accurately with potentially larger dust grains, we provide a practical approach using the series expansions of anomalous diffraction (AD) approximation based on the complicated Mie theory. We apply our calculations to understanding the puzzling X-ray afterglow of recently observed GRB~130925A which showed a significant spectral softening. We find that the X-ray scattering scenarios with either AD or RG approximation adopted could both well reproduce the temporal and spectral profile simultaneously. Given the plateau present in early X-ray light curve, a typical distribution of smaller grains as in the interstellar medium would be suggested for GRB 130925A.
Analysis of the Bacterial Communities in Lime Concretion Black Soil upon the Incorporation of Crop Residues  [PDF]
Shao-Qiang Tao, Qiang Xia, Lin Zhu, Jing-jing Chen, Ya- Nan Wang, Bing Qin
Open Journal of Soil Science (OJSS) , 2012, DOI: 10.4236/ojss.2012.23037
Abstract: To analyze the bacterial communities in lime concretion black soil upon the incorporation of crop residues for two years in wheat-maize system, total DNA was directly extracted and PCR-amplified with the F357GC and R518 primers targeting the 16S rRNA genes of V3 region. The amplified fragments were analyzed by perpendicular DGGE. Analyzing of species richness index S and Shannon diversity index H revealed that there was a high diversity of soil bacterial community compositions among all treatments after incorporation of crop residues and fertilizing under field conditions. Eleven DGGE bands recovered were re-amplified, sequenced. Phylogenetic analysis of the representative DGGE fingerprints identified four groups of the prokaryotic communities in the soil by returning wheat residues and fertilizing under field conditions. The bacterial communities belonged to gamma proteobacterium, Cupriavidus sp, halophilic eubacterium, Acidobacterium sp, Sorangium sp, delta proteobacterium, Streptococcus sp and Streptococcus agalactiae were main bacterial communities. Principal Component Analysis (PCA) showed that there were the differences in DNA profiles among the six treatments. It showed that wheat residue returning, maize residue returning and fertilizing all can improve bacterial diversity in varying degrees. As far as improvement of bacterial diversity was concerned, wheat residue returning was higher than fertilizing, and fertilizing higher than maize residue returning.
Methods for Detecting Side-Effect of Pesticides to Soil Microbial Communities
农药对土壤微生物群落的副作用的研究方法(Methods for Detecting Side-Effect of Pesticides to Soil Microbial Communities)

LI Shao-nan,

生态毒理学报 , 2010,
Abstract: 微生物群落在保持土壤肥力和对外界适应能力方面起着十分重要的作用. 随着农药的广泛应用和农药评估体系的建立与完善,人们越来越关注农药对土壤微生物群落的负面影响,并且尝试用多种方法进行研究. 虽然对其中任何一种方法的使用,均有助于提高人们对农药副作用的认识,但是使用少数几种方法所获得的信息,已能够满足风险评估的最低要求. 论文以农药风险评估的“资料要求”为依据,对“资料要求”中涉及的“碳转化”和“氮转化”两种室内试验的特点和设计思路进行了分析. 此外还简要介绍了国内外农药管理部门在土壤微生物风险评估中常用的几种模型,并探讨了这些模型与具体试验方法之间的关联. 从文中可以看出,对于农药的土壤微生物影响,现已建立起了比较规范化的室内测定方法,目前缺乏的是与风险评估模型相配套的田间试验方法或准则.
A Late Early Permian Phaeophycean Fossil from the Maokou Formation in the Boundary Area Hunan and Hubei Provinces

Feng Shao-nan,

植物学报 , 1989,
Abstract: 本文扼要地叙述湘鄂边境地区下二叠统茅口组上段含碳硅质泥岩(石煤)中褐藻类化石的发现,定名为拟墨角藻(未定种)Quasifucus sp.,并由此推测藻类是形成石煤的一种主要物质成分。
Compact, Ultra-Broadband Coplanar-Waveguide Bandpass Filter with Excellent Stopband Rejection
Shao-Ning Wang;Nan-Wei Chen
PIER B , 2009, DOI: 10.2528/PIERB09071008
Abstract: A compact, ultra-broadband coplanar-waveguide (CPW) bandpass filter (BPF) is demonstrated. The proposed CPW-BPF is essentially designed by exploiting CPW short-stub and open-stub structures. Technically, the proposed filter comprises shunt short-stub and series open-stub structures that are connected in a cascade topology. The higher and lower cutoff frequencies are mainly related to the electrical length of the shunt short stub and the series open stub, respectively. In addition, the stopband rejection is enhanced through an incorporation of CPW bandstop structures. The proposed filter design is verified through experimental demonstration. The corresponding lumped equivalent and transmission-line equivalent circuits are provided for circuit design purpose. Compared with the classical CPW-BPFs, the proposed filter is of a relatively simple and compact configuration. The demonstrated CPW-BPF has about 110% 3-dB fractional bandwidth, sharp selectivity, and great stopband rejection.
A general and facile one-pot process of isothiocyanates from amines under aqueous conditions
Nan Sun,Bin Li,Jianping Shao,Weimin Mo
Beilstein Journal of Organic Chemistry , 2012, DOI: 10.3762/bjoc.8.6
Abstract: A general and facile one-pot protocol for the preparation of a broad range of alkyl and aryl isothiocyanates has been developed from their corresponding primary amines under aqueous conditions. This synthetic process involves an in situ generation of a dithiocarbamate salt from the amine substrate by reacting with CS2 followed by elimination to form the isothiocyanate product with cyanuric acid as the desulfurylation reagent. The choice of solvent is of decisive importance for the successful formation of the dithiocarbamate salt particularly for highly electron-deficient substrates. This novel and economical method is suitable for scale-up activities.
Law Studies for the Circular Economy
Li-zhi NING,Shao-nan WANG
Cross-Cultural Communication , 2006, DOI: 10.3968/609
Abstract: The circular economy requests a feedback flow of “resource-production-reborn resource” for the economic activity, and it sparkplugs decrease, reuse and recycle. Our country should use experiences of the western country for reference, ensure development of circular economy by legislation, and accelerate the pullulating of circular economy and sustainable development of economy by perfecting the three-simultaneity system, budget and statistics system, financial subsidy system, government procurement system, taxation regulation system, producer responsibility system, and clean production system etc. Keywords: circular economy, the principle of 3R, clean production, circular-economy law Résumé L’économie cyclique demande une procédure rétroactive comprenant ressources-produits-ressources renouvelées pour organiser l’activité économique, préconise la réduction, le remploi et le recyclage. Notre pays doit , en s’inspirant des expériences avancées des pays occidentaux, assurer la construction économique par la législation, promouvoir l’économie cyclique et le développement durable de l’économie en perfectionnant le régime de trois en même temps , le système de budget et de statistique, le système des allocations financières, le système d’achats du gouvernement, le système de régulation fiscale, le système de responsabilité des producteurs, le système de production sanitaire, etc. Mots-clés: économie cyclique, principe 3R , production sanitaire, loi de l’économie cyclique 摘 要 循環經濟要求將經濟活動組織成一個“資源—產品—再生資源”的反饋式流程,倡導減量化、再利用和再循環。我國應借鑒西方先進國家經驗,以立法保障循環經濟的建設,並通過完善三同時制度、預算及統計制度、財政補貼制度、政府採購制度、稅收調節制度、生產者責任制度、清潔生產制度等,促進循環經濟的成長和經濟的可持續發展。 關鍵詞:循環經濟; 3R原則;清潔生產;循環經濟法
Adaptive Object Detection and Visibility Improvement in Foggy Image
Nan Dong,Zhen Jia,Jie Shao,Zhipeng Li
Journal of Multimedia , 2011, DOI: 10.4304/jmm.6.1.14-21
Abstract: Detecting objects of interest and obtaining their clear visual appearances are critical requirements for visual surveillance systems. In this paper we propose a novel algorithm to detect foreground objects from video sequences with fog and then enhance their visibilities. First, we propose a novel metric to measure the image fog property to decide whether the image scene is obscured by fog or not. Second, if there is heavy fog in the scene, a novel approach for object detection based on an atmospheric scattering model is proposed. This novel approach can be used to detect not only newly entering objects but also sojourned objects. Once the foreground object is detected, we enhance its visibility only to avoid processing the whole image. Our proposed algorithm is tested with some surveillance video under different fog conditions. Experimental results show that the proposed approach is efficient and efficient for foreground object detection and visibility enhancement under fog weather conditions.
Thermodynamical Metrics and Black Hole Phase Transitions
Haishan Liu,H. Lu,Mingxing Luo,Kai-Nan Shao
Physics , 2010, DOI: 10.1007/JHEP12(2010)054
Abstract: An important phase transition in black hole thermodynamics is associated with the divergence of the specific heat with fixed charge and angular momenta, yet one can demonstrate that neither Ruppeiner's entropy metric nor Weinhold's energy metric reveals this phase transition. In this paper, we introduce a new thermodynamical metric based on the Hessian matrix of several free energy. We demonstrate, by studying various charged and rotating black holes, that the divergence of the specific heat corresponds to the curvature singularity of this new metric. We further investigate metrics on all thermodynamical potentials generated by Legendre transformations and study correspondences between curvature singularities and phase transition signals. We show in general that for a system with n-pairs of intensive/extensive variables, all thermodynamical potential metrics can be embedded into a flat (n,n)-dimensional space. We also generalize the Ruppeiner metrics and they are all conformal to the metrics constructed from the relevant thermodynamical potentials.
Linearized Modes in Extended and Critical Gravities
Yi-Xin Chen,H. Lu,Kai-Nan Shao
Physics , 2011, DOI: 10.1088/0264-9381/29/8/085017
Abstract: We construct explicit solutions for the linearized massive and massless spin-2, vector and scalar modes around the AdS spacetimes in diverse dimensions. These modes may arise in extended (super)gravities with higher curvature terms in general dimensions. Log modes in critical gravities can also be straightforwardly deduced. We analyze the properties of these modes and obtain the tachyon-free condition, which allows negative mass square for these modes. However, such modes may not satisfy the standard AdS boundary condition and can be truncated out from the spectrum.

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