检索结果-南通市图书馆

The spectral properties of Fermi blazars:the spectral sequence and unification of blazars

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2013年第1期13卷 5-14页

作者： Luo-En Chen huai-zhen li Ting-Feng Yi Shu-Bai Zhou Kai-Yi li Physics Department Yuxi Normal University Physics Department Yunan Normal University Physics Department Yunan University

Using a large sample of blazars of the Fermi observations presented by Abdo et al., we constructed a sample of blazars including high energy peaked BL Lac objects （HBLs）, low energy peaked BL Lac objects （LBLs） and flat-spectral ra- dio quasars （FSRQs）. These unique characteristics make it possible to unambiguously address the question of how HBLs, LBLs and FSRQs are related. In this paper, we investigated the relationship between X-ray and 7-ray spectral indices （~^-aT）, as well as the relationship between the broadband spectral indices （~ro--ar~, ~ro--~ox, OZro--O^x7 and ~r^-~xT） for this sample. The color-color diagram shows that there is a significant correlation between both quantities when all three subclasses of blazars are considered, which suggests that there is a unified scheme for blazars. On the other hand, the a^-~7 diagram reveals that three kinds of blazars have different spectral energy distributions： the trend of HBLs is different from that of FSRQs and LBLs, whereas FSRQs and LBLs have a similar trend, which hints that FSRQs and LBLs have similar spectral properties, but HBLs have distinct spectral properties. In addi- tion, the broadband energy distributions also reveal the similar spectral properties with that of the Cx-C7 diagram. The spectral properties revealed from the Fermi sample do not support the blazar sequence reported by Fossati et al. and Ghisellini et al.

关键词： galaxies: active--BL Lacertae objects: general--galaxies: fundamentalparameters -- quasars: general

Quasi-periodic Oscillation Analysis for the BL Lacertae Object 1823+568

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2022年第5期22卷 158-164页

作者： huai-zhen li Quan-Gui Gao Long-Hua Qin Ting-Feng Yi Qi-Rui Chen Physics Department Yuxi Normal UniversityYuxi 653100China Department of Physics Yunnan Normal UniversityKunming 650092China

We studied the optical band periodic variability of 1823+568 using the Jurkevich method,the Lomb-Scargle periodogram and the REDFIT38 software,and found evidence of quasi-periodic *** unprecedented variability with period P=283^(+17)_(-13) days was identified by three different analysis *** quasi-periodic variability most likely results from nonballistic helical jet motion driven by the orbital motion in a binary black hole *** the light-travel time effect,the real physical period is P_(d)=67.1 ***,we estimated that the primary black hole mass is M■1.92×10^(9) M_(⊙)to 3.43×10^(9) M_(⊙).

关键词： blazars(1823+568)-relativisticjets-non-thermalsources

A Periodicity Analysis of the light Curve of 3C 454.3

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Astronomy and Astrophysics 2006年第4期6卷 421-429页

作者： huai-zhen li Guang-Zhong Xie Shu-Bai Zhou Hong-Tao liu Guang-Wei Cha li Ma li-Sheng Mao National Astronomical Observatories / Yunnan Observatory Chinese Academy of Sciences Kunming 650011 Graduate School of Chinese Academy of Sciences Beijing 100049 Yunnan Astronomical Center Yunnan University Kunming 650091 Physics Department Yunnan University Kunming 650091 Physics Department Yunnan Normal College Kunming 650091

We analyzed the radio light curves of 3C 454.3 at frequencies 22 and 37 GHz taken from the database of Metsaeovi Radio Observatory, and found evidence of quasi-periodic activity. The light curves show great activity with very complicated non-sinusoidal variations. Two possible periods, a very weak one of 1.57 ± 0.12 yr and a very strong one of 6.15 ±0.50 yr were consistently identified by two methods, the Jurkevich method and power specmun estimation. The period of 6.15 ± 0.50 yr is consistent with results previously reported by Ciaramella et al. and Webb et al. Applying the binary black hole model to the central structure we found black hole masses of 1.53 × 10^9M⊙ and 1.86 × 10^8M⊙, and predicted that the next radio outburst is to take place in 2006 March and April.

关键词： galaxies: individual (3C 454.3)-- galaxies: fundamental parameters-- methods:data analysis

Estimates of AGN Black Hole Mass and Minimum Variability Timescale

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Astronomy and Astrophysics 2005年第5期5卷 463-470页

作者： Guang-Zhong Xie Luo-En Chen huai-zhen li li-Sheng Mao Hong Dai Zhao-Hua Xie li Ma Shu-Bai Zhou National Astronomical Observatories Yunnan Observatory Chinese Academy of ScienceKunming 650011 Yunnan Astrophysics Center Yunnan University Kunming 650091 Physics Department Yunnan Normal University Kunming 650091 Physics Department Yuxi Normal College Yuxi 653100 Graduate University of Chinese Academy of Sciences Beijing 100049

Black hole mass is one of the fundamental physical parameters of active galactic nuclei （AGNs）, for which many methods of estimation have been proposed. One set of methods assumes that the broad-line region （BLR） is gravitationally bound by the central black hole potential, so the black hole mass can be estimated from the orbital radius and the Doppler velocity. Another set of methods assumes the observed variability timescale is determined by the orbital timescale near the innermost stable orbit around the Schwarzschild black hole or the Kerr black hole, or by the characteristic timescale of the accretion disk. We collect a sample of 21 AGNs, for which the minimum variability timescales have been obtained and their black hole masses （Mσ） have been well estimated from the stellar velocity dispersion or the BLR size-luminosity relation. Using the minimum variability timescales we estimated the black hole masses for 21 objects by the three different methods, the results are denoted by Ms, Mk and Md,respectively. We compared each of them with Mσ individually and found that：（1） using the minimum variability timescale with the Kerr black hole theory leads to small differences between Mσ and Mk, none exceeding one order of magnitude, and the mean difference between them is about 0.53 dex; （2） using the minimum variability timescale with the Schwarzschild black hole theory leads to somewhat larger difference between Mσ and Ms： larger than one order of magnitude for 6 of the 21 sources, and the mean difference is 0.74 dex; （3） using the minimum variability timescale with the accretion disk theory leads to much larger differences between Mσ and Md, for 13 of the 21 sources the differences are larger than two orders of magnitude; and the mean difference is as high as about 2.01 dex.

关键词： galaxies: active - galaxies: nuclei - galaxies: fundamental parameters

Possible properties of Te V spectra in PKS 2155–304

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2021年第3期21卷 227-234页

作者： Quan-Gui Gao Fang-Wu Lu Long-Hua Qin huai-zhen li Ju Ma Ji-Yang Ren Hai-Ru Zhao Ting-Feng Yi Physics Department Yuxi Normal UniversityYuxi 653100China Key Laboratory of Astroparticle Physics of Yunnan Province Kunming 650091China Department of Physics Yunnan Normal UniversityKunming 650092China

We present a one-zone homogeneous lepton-hadronic model and obtain steady-state spectra by solving the time-dependent equations to study a plausible origin of hard TeV spectra in PKS *** this model,we assume a steady electron and proton injection rate in the source and solve the non-linear time-dependent kinematic equations that self-consistently consist of proton-photon interaction,synchrotron radiation of electron/positron pairs and proton,inverse Compton scattering,and synchrotron *** employ this model to reproduce the multi-wavelength spectrum of PKS 2155-304,then find that the possible bump located at E~1 TeV which may originate from the synchrotron radiation of secondary electrons produced by Bethe-Heitler pair production,resulting in the hard TeV spectrum.

关键词： radiation mechanisms:non-thermal BL Lacertae objects:individual(PKS 2155–304) gamma rays:galaxies

Physiological Mechanism of High and Stable Yield of No-tillage Cast-transplanted Rice

在线全文

学校读者我要写书评

暂无评论

Agricultural Sciences in China 2002年第4期1卷 404-409页

作者： liU Jun, HUANG Qing, FU Hua, LU Xiu-ming, liU huai-zhen and li Kang-huo( Rice Research Institute , Guangdong Academy of Agricultural Sciences , Guangzhou 510640 , P.R. China) Rice Research Institute Guangdong Academy of Agricultural Sciences Guangzhou 510640 P. R . China

Four years' successive comparative experiments showed that no-tillage cast-transplanted rice (NTCTR), compared with conventional tillage cast-transplanted rice (CK), grew slower and produced less tillers at the early growing stage; but, it had shorter ineffective tillering time, less nutrition consumption, stronger individual growth and more uniform growth between individuals and the colony. These characteristics contribute to the increase not only in the productive tiller percentage but also in the ear quality. Furthermore, the flag leaf of NTCTR had higher photosynthetic rate during the filling stage and no early senescence phenomenon at the late stage, which facilitated the accumulation and the transportation of carbohydrates and improved grain setting rate.

关键词： Rice No-tillage cast-transplanted rice(NTCTR) Physiology

Local magnetic moment oscillation around an Anderson impurity on graphene

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 192-201页

作者： Shuai li zhen Ma Jin-Hua Gao School of Science Hebei University of Science and Technology School of Electronics and Information Zhengzhou University of Light Industry School of Physics and Wuhan National High Magnetic Field Center Huazhong University of Science and Technology

We theoretically investigate the spin resolved Friedel oscillation （FO） and quasiparticle interference （QPI） in graphene induced by an Anderson *** the impurity becomes magnetic,the resulted FO becomes spin dependent,which gives rise to a local magnetic moment oscillation with an envelop decaying as r-2in real space in the doping ***,at half filling,the electron density and local magnetic moment will not oscillate but decay as *** spin resolved FO has both sublattice and spin ***,the local magnetic moment decay at half filling only occurs at one sublattice of graphene,which is quite like the phenomenon observed in the STM experiment (***ález-Herrero et al.,Science 352,437 （2016）).We further give an analytic formula about such spin dependent FO based on the stationary phase ***,we study the interference of quasiparticles around the magnetic impurity by calculating the spin dependent Fourier-transformed local density of states （FT-LDOS）.Our work gives a comprehensive understanding about the local magnetic moment oscillation around an Anderson impurity on graphene.

关键词： Friedel oscillation local magnetic moment graphene Anderson impurity

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

不同土地利用方式对红壤微生物多样性的影响

水土保持学报 2003年第2期17卷 51-54页

作者：姚槐应何振立黄昌勇浙江大学资源科学系杭州310029

试验采用碳素利用(BIOLOG)及磷酸酯脂肪酸(PLFA)法,研究了8种供试红壤微生物群落的功能多样性和结构多样性。两种方法均表明土地利用方式能显著影响微生物的多样性。采用磷酸酯脂肪酸法无需培养就能鉴别土壤微生物的组成结构,试验表明总... 详细信息

试验采用碳素利用(BIOLOG)及磷酸酯脂肪酸(PLFA)法,研究了8种供试红壤微生物群落的功能多样性和结构多样性。两种方法均表明土地利用方式能显著影响微生物的多样性。采用磷酸酯脂肪酸法无需培养就能鉴别土壤微生物的组成结构,试验表明总PLFA含量与微生物生物量呈显著相关。碳素利用法的研究结果显示,茶叶园土中微生物对各类碳源的利用能力均很低,呈现出非常独特的微生物功能多样性。

关键词：土地利用方式红壤土壤微生物多样性碳素利用磷酸酯脂肪酸

liver as a new target organ in Alzheimer's disease:insight from cholesterol metabolism and its role in amyloid-beta clearance

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第3期20卷 695-714页

作者： Beibei Wu Yuqing liu Hongli li Lemei Zhu lingfeng Zeng zhen Zhang Weijun Peng Department of Integrated Traditional Chinese&Western Medicine The Second Xiangya HospitalCentral South UniversityChangshaHunan ProvinceChina Academician Workstation Changsha Medical UniversityChangshaHunan ProvinceChina Yangsheng College of Traditional Chinese Medicine Guizhou University of Traditional Chinese MedicineGuiyangGuizhou ProvinceChina Qinhuangdao Shanhaiguan Pharmaceutical Co. LtdQinhuangdaoHebei ProvinceChina National Clinical Research Center for Mental Disorder The Second Xiangya HospitalCentral South UniversityChangshaHunan ProvinceChina

Alzheimer's disease,the primary cause of dementia,is characterized by neuropathologies,such as amyloid plaques,synaptic and neuronal degeneration,and neurofibrillary *** amyloid plaques are the primary characteristic of Alzheimer's disease in the central nervous system and peripheral organs,targeting amyloid-beta clearance in the central nervous system has shown limited clinical efficacy in Alzheimer's disease *** abnormalities are commonly observed in patients with Alzheimer's *** liver is the primary peripheral organ involved in amyloid-beta metabolism,playing a crucial role in the pathophysiology of Alzheimer's ***,impaired cholesterol metabolism in the liver may exacerbate the development of Alzheimer's *** this review,we explore the underlying causes of Alzheimer's disease and elucidate the role of the liver in amyloid-beta clearance and cholesterol ***,we propose that restoring normal cholesterol metabolism in the liver could represent a promising therapeutic strategy for addressing Alzheimer's disease.

关键词： ABCA1 Alzheimer's disease amyloid-beta apolipoprotein E cholesterol metabolism liver liver X receptor low-density lipoprotein receptor-related protein 1 peripheral clearance tauroursodeoxycholic acid