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Protective effect of Salvia miltiorrhiza and Carthamus tinctorius extract against lipopolysaccharide-induced liver injury 被引量:9
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作者 Li-Na Gao Kuo Yan +2 位作者 Yuan-Lu Cui Guan-Wei Fan yue-fei wang 《World Journal of Gastroenterology》 SCIE CAS 2015年第30期9079-9092,共14页
AIM:To investigate the hepatoprotective effects and mechanisms of an extract of Salvia miltiorrhiza and Carthamus tinctorius in vivo.METHODS:C57BL/6J mice were randomly assigned to five groups and intraperitoneally ad... AIM:To investigate the hepatoprotective effects and mechanisms of an extract of Salvia miltiorrhiza and Carthamus tinctorius in vivo.METHODS:C57BL/6J mice were randomly assigned to five groups and intraperitoneally administered 0.9% saline,Salvia miltiorrhiza and Carthamus tinctorius extract [Danhong injection(DHI),0.75 and 3 g/kg mixed extract] or reduced glutathione for injection(RGI,300 mg/kg) for 30 min before exposure to lipopolysaccharide(LPS,16 mg/kg). After intraperitoneal LPS stimulation for 90 min or 6 h,the mice were sacrificed by ether anaesthesia,and serum and liver samples were collected. Histological analysis(H&E) and terminal deoxynucleotidyl transferase-mediated d UTP nick end-labelling(TUNEL) staining were performed. Alanine transferase(ALT),aspartate transaminase(AST),total bilirubin(TBil),glutathione-S-transferase(GST),malondialdehyde(MDA),tumour necrosis factor(TNF)-α,interleukin(IL)-6,and caspase-3 levels were measured. Bax,Bcl-2,P-IκBα,IκBα,P-NF-κB p65,and NF-κB p65 protein levels were determined by Western blot. TNF-α,IL-6,caspase-3,Bax and Bcl-2 m RNA expression was measured by real-time reverse transcription-polymerase chain reaction(RT-PCR).RESULTS:Hematoxylin-eosin staining and TUNEL results suggested that DHI(3 g/kg) treatment alleviated inflammatory and apoptotic(P < 0.01) injury in the liver of mice. DHI treatment dose-dependently blunted the abnormal changes in biochemical parameters such as ALT(72.53 ± 2.83 for 3 g/kg,P < 0.01),AST(76.97 ± 5.00 for 3 g/kg,P < 0.01),TBil(1.17 ± 0.10 for 3 g/kg,P < 0.01),MDA(0.81 ± 0.36 for 3 g/kg,P < 0.01),and GST(358.86 ± 12.09 for 3 g/kg,P < 0.01). Moreover,DHI(3 g/kg) remarkably decreased LPS-induced protein expression of TNF-α(340.55 ± 10.18 for 3 g/kg,P < 0.01),IL-6(261.34 ± 10.18 for 3 g/kg,P < 0.01),and enzyme activity of caspase-3(0.93 ± 0.029 for 3 g/kg,P < 0.01). The LPS-induced m RNA expression of TNF-α,IL-6 and caspase-3 was also decreased by DHI. Western blot analysis revealed that DHI antagonised LPS-stimulated decrease of Bcl-2 and increase of Bax protein expression. Furthermore,DHI inhibited LPS-induced IκBα and NF-κB p65 phosphorylation.CONCLUSION:DHI may be a multi-function protectant against acute hepatic injury in mice through its antiinflammatory,anti-oxidative and anti-apoptotic activities. 展开更多
关键词 SALVIA miltiorrhiza CARTHAMUS tinctorius Apoptosis ANTI-INFLAMMATORY ANTIOXIDANT Acute liverinjury
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Mapping the Milky Way with LAMOSTⅠ:method and overview 被引量:5
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作者 Chao Liu Yan Xu +8 位作者 Jun-Chen Wan Hai-Feng wang Jeffrey L.Carlin Li-Cai Deng Heidi Jo Newberg Zi-Huang Cao Yong-Hui Hou yue-fei wang Yong Zhang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2017年第9期81-100,共20页
We present a statistical method to derive the stellar density profiles of the Milky Way from spectroscopic survey data, taking into account selection effects. We assume the selection function, which can be altered dur... We present a statistical method to derive the stellar density profiles of the Milky Way from spectroscopic survey data, taking into account selection effects. We assume the selection function, which can be altered during observations and data reductions, of the spectroscopic survey is based on photometric colors and magnitude. Then the underlying selection function for a line-of-sight can be recovered well by comparing the distribution of the spectroscopic stars in a color-magnitude plane with that of the photometric dataset. Subsequently, the stellar density profile along a line-of-sight can be derived from the spectroscopically measured stellar density profile multiplied by the selection function. The method is validated using Galaxia mock data with two different selection functions. We demonstrate that the derived stellar density profiles reconstruct the true ones well not only for the full set of targets, but also for sub-populations selected from the full dataset. Finally, the method is applied to map the density pro- files for the Galactic disk and halo, using the LAMOST RGB stars. The Galactic disk extends to about R = 19 kpc, where the disk still contributes about 10% to the total stellar surface density. Beyond this radius, the disk smoothly transitions to the halo without any truncation, bending or breaking. Moreover, no over-density corresponding to the Monoceros ring is found in the Galactic anti-center direction. The disk shows moderate north-south asymmetry at radii larger than 12 kpc. On the other hand, the R-Z tomographic map directly shows that the stellar halo is substantially oblate within a Galactocentric radius of 20 kpc and gradually becomes nearly spherical beyond 30 kpc. 展开更多
关键词 methods: statistical -- Galaxy structure -- Galaxy disk - Galaxy halo - surveys LAMOST
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Preliminary study of a dispersed fringe type sensing system 被引量:3
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作者 Yong Zhang Gen-Rong Liu +3 位作者 yue-fei wang Ye-Ping Li Ya-Jun Zhang Liang Zhan-g 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2009年第8期945-952,共8页
Telescopes with large aspherical primary mirrors collect more light and are therefore sought after by astronomers. Instead of using a single large one-piece mirror, smaller segments can be assembled into a useable tel... Telescopes with large aspherical primary mirrors collect more light and are therefore sought after by astronomers. Instead of using a single large one-piece mirror, smaller segments can be assembled into a useable telescopic primary. Because the segments must fit together to create the effect of a single mirror, segmented optics present unique challenges to the fabrication and testing that are absent in monolithic optics. A dispersed fringe sensor (DFS) using a broadband point source is an efficient method for cophasing and is also highly automated and robust. Unlike the widely adopted Shack- Hartmann Wavefront sensor and curvature wavefront sensor with edge sensors for calibration of relative pistons, DFS can estimate the piston between segments by only using the spectrum formed by the transmissive grating's dispersion, and therefore can replace the edge sensors, which are difficult to calibrate. We introduce the theory of the DFS and Dispersed Hartmann Sensor (DHS) for further utilization of the coarse phasing method of DFS. According to the theory, we bring out the preliminary system design of the cophasing experimental system based on DFS and DHS which is now established in our institute. Finally, a summary is reached. 展开更多
关键词 INSTRUMENTATION active optics -- techniques image processing -- tech- niques spectroscopic -- telescope cophasing sensor
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The first data release(DR1) of the LAMOST regular survey 被引量:29
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作者 A-Li Luo Yong-Heng Zhao +142 位作者 Gang Zhao Li-Cai Deng Xiao-Wei Liu Yi-Peng Jing Gang wang Hao-Tong Zhang Jian-Rong Shi Xiang-Qun Cui Yao-Quan Chu Guo-Ping Li Zhong-Rui Bai Yue Wu Yan Cai Shu-Yun Cao Zi-Huang Cao Jeffrey L.Carlin Hai-Yuan Chen Jian-Jun Chen Kun-Xin Chen Li Chen Xue-Lei Chen Xiao-Yan Chen Ying Chen Norbert Christlieb Jia-Ru Chu Chen-Zhou Cui Yi-Qiao Dong Bing Du Dong-Wei Fan Lei Feng Jian-Ning Fu Peng Gao Xue-Fei Gong Bo-Zhong Gu Yan-Xin Guo Zhan-Wen Han Bo-Liang He Jin-Liang Hou Yong-Hui Hou Wen Hou Hong-Zhuan Hu Ning-Sheng Hu Zhong-Wen Hu Zhi-Ying Huo Lei Jia Fang-Hua Jiang Xiang Jiang Zhi-Bo Jiang Ge Jin Xiao Kong Xu Kong Ya-Juan Lei Ai-Hua Li Chang-Hua Li Guang-Wei Li Hai-Ning Li Jian Li Qi Li Shuang Li Sha-Sha Li Xin-Nan Li Yan Li Yin-Bi Li Ye-Ping Li Yuan Liang Chien-Cheng Lin Chao Liu Gen-Rong Liu Guan-Qun Liu Zhi-Gang Liu Wen-Zhi Lu Yu Luo Yin-Dun Mao Heidi Newberg Ji-Jun Ni Zhao-Xiang Qi Yong-Jun Qi Shi-Yin Shen Huo-Ming Shi Jing Song Yi-Han Song Ding-Qiang Su Hong-Jun Su Zheng-Hong Tang Qing-Sheng Tao Yuan Tian Dan wang Da-Qi wang Feng-Fei wang Guo-Min wang Hai wang Hong-Chi wang Jian wang Jia-Ning wang Jian-Ling wang Jian-Ping wang Jun-Xian wang Lei wang Meng-Xin wang Shou-Guan wang Shu-Qing wang Xia wang Ya-Nan wang You wang yue-fei wang You-Fen wang Peng Wei Ming-Zhi Wei Hong Wu Ke-Fei Wu Xue-Bing Wu Yu-Zhong Wu Xiao-Zheng Xing Ling-Zhe Xu Xin-Qi Xu Yan Xu Tai-Sheng Yan De-Hua Yang Hai-Feng Yang Hui-Qin Yang Ming Yang Zheng-Qiu Yao Yong Yu Hui Yuan Hai-Bo Yuan Hai-Long Yuan Wei-Min Yuan Chao Zhai En-Peng Zhang Hua-Wei Zhang Jian-Nan Zhang Li-Pin Zhang Wei Zhang Yong Zhang Yan-Xia Zhang Zheng-Chao Zhang Ming Zhao Fang Zhou Xu Zhou Jie Zhu Yong-Tian Zhu Si-Cheng Zou Fang Zuo 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2015年第8期1095-1124,共30页
The Large sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST) general survey is a spectroscopic survey that will eventually cover approximately half of the celestial sphere and collect 10 million spectra of ... The Large sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST) general survey is a spectroscopic survey that will eventually cover approximately half of the celestial sphere and collect 10 million spectra of stars, galaxies and QSOs. Objects in both the pilot survey and the first year regular survey are included in the LAMOST DR1. The pilot survey started in October 2011 and ended in June 2012, and the data have been released to the public as the LAMOST Pilot Data Release in August 2012. The regular survey started in September 2012, and completed its first year of operation in June 2013. The LAMOST DR1 includes a total of 1202 plates containing 2 955 336 spectra, of which 1 790 879 spectra have observed signalto-noise ratio(SNR) ≥ 10. All data with SNR ≥ 2 are formally released as LAMOST DR1 under the LAMOST data policy. This data release contains a total of 2 204 696 spectra, of which 1 944 329 are stellar spectra, 12 082 are galaxy spectra and 5017 are quasars. The DR1 not only includes spectra, but also three stellar catalogs with measured parameters: late A,FGK-type stars with high quality spectra(1 061 918 entries), A-type stars(100 073 entries), and M-type stars(121 522 entries). This paper introduces the survey design, the observational and instrumental limitations, data reduction and analysis, and some caveats. A description of the FITS structure of spectral files and parameter catalogs is also provided. 展开更多
关键词 techniques: spectroscopic survey—data release—catalog
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Spectral classification of stars based on LAMOST spectra 被引量:9
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作者 Chao Liu Wen-Yuan Cui +6 位作者 Bo Zhang Jun-Chen Wan Li-Cai Deng Yong-Hui Hou yue-fei wang Ming Yang Yong Zhang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2015年第8期1137-1153,共17页
In this work, we select spectra of stars with high signal-to-noise ratio from LAMOST data and map their MK classes to the spectral features. The equivalent widths of prominent spectral lines, which play a similar role... In this work, we select spectra of stars with high signal-to-noise ratio from LAMOST data and map their MK classes to the spectral features. The equivalent widths of prominent spectral lines, which play a similar role as multi-color photometry, form a clean stellar locus well ordered by MK classes. The advantage of the stellar locus in line indices is that it gives a natural and continuous classification of stars consistent with either broadly used MK classes or stellar astrophysical parameters. We also employ an SVM-based classification algorithm to assign MK classes to LAMOST stellar spectra. We find that the completenesses of the classifications are up to 90% for A and G type stars, but they are down to about 50% for OB and K type stars. About 40% of the OB and K type stars are mis-classified as A and G type stars,respectively. This is likely due to the difference in the spectral features between late B type and early A type stars or between late G and early K type stars being very weak. The relatively poor performance of the automatic MK classification with SVM suggests that the direct use of line indices to classify stars is likely a more preferable choice. 展开更多
关键词 techniques: spectroscopic—stars: general—stars: fundamental parameters—stars: statistics—Galaxy: stellar contents
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Data release of the LAMOST pilot survey 被引量:8
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作者 A-Li Luo Hao-Tong Zhang +80 位作者 Yong-Heng Zhao Gang Zhao Xiang-Qun Cui Guo-Ping Li Yao-Quan Chu Jian-Rong Shi Gang wang Jian-Nan Zhang Zhong-Rui Bai Xiao-Yan Chen Feng-Fei wang Yan-Xin Guo Jian-Jun Chen Bing Du Xiao Kong Ya-Juan Lei Yin-Bi Li Yi-Han Song Yue Wu Yan-Xia Zhang Xin-Lin Zhou Fang Zuo Peng Du Lin He Wen Hou Yi-Qiao Dong Jian Li Guang-Wei Li Shuang Li Jing Song Yuan Tian Meng-Xin wang Yong-Hui Hou Zhi-Ying Huo Hong-Zhuan Hu Ning-Sheng Hu Zhong-Wen Hu Lei Jia Fang-Hua Jiang Xiang Jiang Zi-Bo Jiang Ge Jin Ai-Hua Li Qi Li Yin-Dun Mao Zheng-Hong Tang Qing-Sheng Tao Liang-Ping Tu Da-Qing wang Dan wang Jian-Ping wang Lei wang Shou-Guan wang Shu-Qing wang Ya-Nan wang You wang yue-fei wang Ming-Zhi Wei Xiang-Xiang Xue Xiao-Zheng Xing Ling-Zhe Xu Xin-Qi Xu Yan Xu De-Hua Yang Shi-Hai Yang Zheng-Qiu Yao Yong Yu Hui Yuan Chao Zhai En-Peng Zhang Jing Zhang Li-Ping Zhang WeiZhang Yong Zhang Zhen-Chao Zhang Ming Zhao Fang Zhou Yong-Tian Zhu Jie Zhu Si-Cheng Zou 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2012年第9期1243-1246,共4页
This paper describes the data release of the LAMOST pilot survey, which includes data reduction, calibration, spectral analysis, data products and data access. The accuracy of the released data and the information abo... This paper describes the data release of the LAMOST pilot survey, which includes data reduction, calibration, spectral analysis, data products and data access. The accuracy of the released data and the information about the FITS headers of spectra are also introduced. The released data set includes 319 000 spectra and a catalog of these objects. 展开更多
关键词 techniques: spectroscopic survey data reduction data release
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A method of measuring the [α/Fe] ratios from the spectra of the LAMOST survey 被引量:1
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作者 Ji Li Chen Han +13 位作者 Mao-Sheng Xiang Jian-Rong Shi Jing-Kun Zhao Xiao-Wei Liu Hua-Wei Zhang Hai-Bo Yuan Xuan Ci Xiao-Feng Zhang Yue-Xiang wang Yang Huang Yong Zhang Yong-Hui Hou yue-fei wang Zi-Huang Cao 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2016年第7期83-96,共14页
The [α/Fe] ratios in stars are good tracers to probe the formation history of stellar populations and the chemical evolution of the Galaxy. The spectroscopic survey of LAMOST provides a good opportunity to determine ... The [α/Fe] ratios in stars are good tracers to probe the formation history of stellar populations and the chemical evolution of the Galaxy. The spectroscopic survey of LAMOST provides a good opportunity to determine [α/Fe] of millions of stars in the Galaxy. We present a method of measuring the [α/Fe]ratios from LAMOST spectra using the template-matching technique of the LSP3 pipeline. We use three test samples of stars selected from the ELODIE and MILES libraries, as well as the LEGUE survey to validate our method. Based on the test results, we conclude that our method is valid for measuring [α/Fe]from low-resolution spectra acquired by the LAMOST survey. Within the range of the stellar parameters Teff= [5000, 7500] K, log g = [1.0, 5.0] dex and [Fe/H]= [onsistent with values derived from high-resolution spectra,-1.5, +0.5] dex, our [α/Fe] measurements are c and the accuracy of our [α/Fe] measurements from LAMOST spectra is better than 0.1 dex with spectral signal-to-noise higher than 20. 展开更多
关键词 GALAXY evolution stars abundances stars fundamental parameters techniques spectroscopy surveys methods data analysis
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A catalog of early-type emission-line stars and Hα line profiles from LAMOST DR2 被引量:1
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作者 Wen Hou A-Li Luo +9 位作者 Jing-Yao Hu Hai-Feng Yang Chang-De Du Chao Liu Chien-De Lee Chien-Cheng Lin yue-fei wang Yong Zhang Zi-Huang Cao Yong-Hui Hou 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2016年第9期39-50,共12页
We present a catalog including 11 204 spectra of 10436 early-type emission-line stars from LAMOST DR2, among which 9752 early-type emission-line spectra are newly discovered. For these early- type emissionqine stars, ... We present a catalog including 11 204 spectra of 10436 early-type emission-line stars from LAMOST DR2, among which 9752 early-type emission-line spectra are newly discovered. For these early- type emissionqine stars, we discuss the morphological and physical properties of their low-resolution spectra. In this spectral sample, the Hα emission profiles display a wide variety of shapes. Based on the Hα line profiles, these spectra are categorized into five distinct classes: single-peak emission, single-peak emission in absorption, double-peak emission, double-peak emission in absorption, and P-Cygni profiles. To better understand what causes the Hc~ line profiles, we divide these objects into four types from the perspective of physical classification, which include classical Be stars, Herbig Ae/Be stars, close binaries and spectra contaminated by H n regions. The majority of Herbig Ae/Be stars and classical Be stars are identified and separated using a (H-K, K-W1) color-color diagram. We also discuss 31 binary systems that are listed in the SIMBAD on-line catalog and identify 3600 spectra contaminated by HⅡ regions after cross-matching with positions in the Dubout-Crillon catalog. A statistical analysis of line profiles versus classifications is then conducted in order to understand the distribution of Hc~ profiles for each type in our sample. Finally, we also provide a table of 172 spectra with Fen emission lines and roughly calculate stellar wind velocities for seven spectra with P-Cygni profiles. 展开更多
关键词 STARS early-type - stars emission-line Be -- stars pre-main sequence -- binaries close
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A search for Mg-poor stars using LAMOST survey data 被引量:2
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作者 Qian-Fan Xing Gang Zhao +3 位作者 Yong Zhang Yong-Hui Hou yue-fei wang Yue Wu 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2015年第8期1275-1281,共7页
Most Galactic metal-poor stars exhibit enhanced α-abundances(e.g.[Mg/Fe] ~ +0.4) according to previous studies of stellar chemical compositions.However, a handful of metal-poor stars with large deficiencies in Mg... Most Galactic metal-poor stars exhibit enhanced α-abundances(e.g.[Mg/Fe] ~ +0.4) according to previous studies of stellar chemical compositions.However, a handful of metal-poor stars with large deficiencies in Mg(e.g. [Mg/Fe]~-0.2) show severe departures from this α-enhancement trend. The sub-solar[Mg/Fe] ratios of these anomalous stars indicate that they possess different chemical enrichment histories than the majority of Galactic metal-poor stars. In previous work,we presented a method to select Mg-poor metal-poor stars from low-resolution SDSS spectra based on a spectral matching technique. In this paper, a similar method is applied to low-resolution(R ~ 1800) LAMOST spectra. Stellar [Mg/Fe] abundances are determined by using stellar parameters delivered by the LAMOST Data Release2 catalog. From a sample of ~ 60 000 stars with atmospheric parameters in the range Teff = [5500, 6500] K and [Fe/H] = [-2.4, +0.5], we select 15 candidate Mg-poor metal-poor stars. 展开更多
关键词 methods: data analysis—stars: abundance—stars: atmospheres
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The 30-Day Oral Administration Studies of Liposoluble Tea Polyphenols in Rats 被引量:2
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作者 Liang-Peng Lin Da Sun +4 位作者 yue-fei wang Da-Wei Li Shi-Kang Zhang Yue-Jin Zhu Pu-Ming He 《茶叶》 2013年第4期325-332,共8页
Tea polyphenols is a natural antioxidant with a variety of biological activity.However,the weak liposolubility and low bioavailability limit their application.As a result,structural modification of tea polyphenols com... Tea polyphenols is a natural antioxidant with a variety of biological activity.However,the weak liposolubility and low bioavailability limit their application.As a result,structural modification of tea polyphenols comes into being.The prepared liposoluble tea polyphenols was suggested as a good candidate antioxidant for edible-oil and fats products.But,safety studies on liposoluble tea polyphenols are limited.The objective of the present study was conducted to synthesize liposoluble tea polyphenols and evaluate its toxicity in Sprague-Dawley rats on oral administration at dietary levels of 1,2 and 4% for 30 days.There were no adverse effects on general condition,growth,food intake,feed conversion efficiency,haematology parameters,clinical chemistry values and organ weights.High-dose males exhibited a higher haemoglobin concentration and a lower alanine aminotransferase levels,and high-dose females showed a lower albumin and globulin levels.These slight changes were considered of no toxicological significance.Necropsy and histopathology findings revealed no treatment-related changes in any of the organs.Thus,the results allowed us to conclude that the liposoluble tea polyphenols properly utilized in the oral administration could be devoid of any toxic risk. 展开更多
关键词 脂溶性茶多酚 口服给药 SPRAGUE-DAWLEY 大鼠 天然抗氧化剂 血红蛋白浓度 器官重量 生物利用度
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On the metallicity gradients of the Galactic disk as revealed by LSS-GAC red clump stars 被引量:2
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作者 Yang Huang Xiao-Wei Liu +10 位作者 Hua-Wei Zhang Hai-Bo Yuan Mao-Sheng Xiang Bing-Qiu Chen Juan-Juan Ren Ning-Chen Sun Chun wang Yong Zhang Yong-Hui Hou yue-fei wang Ming Yang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2015年第8期1240-1263,共24页
Using a sample of over 70 000 red clump(RC) stars with 5%–10% distance accuracy selected from the LAMOST Spectroscopic Survey of the Galactic Anti-center(LSS-GAC), we study the radial and vertical gradients of th... Using a sample of over 70 000 red clump(RC) stars with 5%–10% distance accuracy selected from the LAMOST Spectroscopic Survey of the Galactic Anti-center(LSS-GAC), we study the radial and vertical gradients of the Galactic disk(s) mainly in the anti-center direction, covering a significant volume of the disk in the range of projected Galactocentric radius 7 ≤ RGC ≤ 14 kpc and height from the Galactic midplane 0 ≤ |Z | ≤ 3 kpc. Our analysis shows that both the radial and vertical metallicity gradients are negative across much of the volume of the disk that is probed, and they exhibit significant spatial variations. Near the solar circle(7 ≤ RGC ≤ 11.5 kpc), the radial gradient has a moderately steep, negative slope of-0.08 dex kpc-1near the midplane(|Z | 〈 0.1 kpc), and the slope flattens with increasing |Z |. In the outer disk(11.5 〈 RGC ≤ 14 kpc), the radial gradients have an essentially constant, much less steep slope of-0.01 dex kpc-1at all heights above the plane, suggesting that the outer disk may have experienced an evolutionary path different from that of the inner disk. The vertical gradients are found to flatten largely with increasing RGC. However, the vertical gradient of the lower disk(0 ≤ |Z | ≤ 1 kpc)is found to flatten with RGC quicker than that of the upper disk(1 〈 |Z | ≤ 3 kpc).Our results should provide strong constraints on the theory of disk formation and evolution, as well as the underlying physical processes that shape the disk(e.g. gas flows,radial migration, and internal and external perturbations). 展开更多
关键词 Galaxy: abundances—Galaxy: disk—Galaxy: evolution—Galaxy: formation—techniques: spectroscopic
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19 low mass hypervelocity star candidates from the first data release of the LAMOST survey 被引量:2
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作者 Yin-Bi Li A-Li Luo +12 位作者 Gang Zhao You-Jun Lu Peng Wei Bing Du Xiang Li Yong-Heng Zhao Zhan-Wen Han Bo wang Yue Wu Yong Zhang Yong-Hui Hou yue-fei wang Ming Yang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2015年第8期1364-1377,共14页
Hypervelocity stars are believed to be ejected out from the Galactic center through dynamical interactions between(binary) stars and the central supermassive black hole(s). In this paper, we report 19 low mass F/G... Hypervelocity stars are believed to be ejected out from the Galactic center through dynamical interactions between(binary) stars and the central supermassive black hole(s). In this paper, we report 19 low mass F/G/K type hypervelocity star candidates from over one million stars found in the first data release of the LAMOST regular survey. We determine the unbound probability for each candidate using a MonteCarlo simulation by assuming a non-Gaussian proper-motion error distribution, and Gaussian heliocentric distance and radial velocity error distributions. The simulation results show that all the candidates have unbound possibilities over 50% as expected,and one of them may even exceed escape velocity with over 90% probability. In addition, we compare the metallicities of our candidates with the metallicity distribution functions of the Galactic bulge, disk, halo and globular clusters, and conclude that the Galactic bulge or disk is likely the birth place for our candidates. 展开更多
关键词 stars: low-mass—stars: kinematics and dynamics—Galaxy: abundances—stars: fundamental parameters—stars: distances
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Galactic disk bulk motions as revealed by the LSS-GAC DR2 被引量:2
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作者 Ning-Chen Sun Xiao-Wei Liu +10 位作者 Yang Huang Hai-Bo Yuan Mao-Sheng Xiang Hua-Wei Zhang Bing-Qiu Chen Juan-Juan Ren Chun wang Yong Zhang Yong-Hui Hou yue-fei wang Ming Yang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2015年第8期1342-1363,共22页
We report a detailed investigation of the bulk motions of the nearby Galactic stellar disk, based on three samples selected from the LSS-GAC DR2: a global sample containing 0.57 million FGK dwarfs out to ~2 kpc, a l... We report a detailed investigation of the bulk motions of the nearby Galactic stellar disk, based on three samples selected from the LSS-GAC DR2: a global sample containing 0.57 million FGK dwarfs out to ~2 kpc, a local subset of the global sample consisting of ~5400 stars within 150 pc, and an anti-center sample containing ~4400AFGK dwarfs and red clump stars within windows a few degrees wide centered on the Galactic Anti-center. The global sample is used to construct a three-dimensional map of bulk motions of the Galactic disk from the solar vicinity out to ~2 kpc with a spatial resolution of ~250 pc. Typical values of the radial and vertical components of bulk motion range from-15 km s-1to 15 km s-1; in contrast, the lag behind the circular motion dominates the azimuthal component by up to ~15 km s-1. The map reveals spatially coherent, kpc-scale stellar flows in the disk, with typical velocities of a few tens of km s-1. Bending- and breathing-mode perturbations are clearly visible,and vary smoothly across the disk plane. Our data also reveal higher-order perturbations, such as breaks and ripples, in the profiles of vertical motion versus height. From the local sample, we find that stars from different populations exhibit very different patterns of bulk motion. Finally, the anti-center sample reveals a number of peaks in stellar number density in the line-of-sight velocity versus distance distribution, with the nearer ones apparently related to the known moving groups. The "velocity bifurcation" reported by Liu et al. at Galactocentric radii 10–11 kpc is confirmed. However,just beyond this distance, our data also reveal a new triple-peaked structure. 展开更多
关键词 Galaxy: disk-Galaxy: kinematics and dynamics-Galaxy: stellar content
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M Dwarf catalog of LAMOST general survey data release one 被引量:1
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作者 Yan-Xin Guo Zhen-Ping Yi +19 位作者 A-Li Luo You-Fen wang Yu Bai Hai-Feng Yang Yi-Han Song Jian-Jun Chen Xiao-Yan Chen Fang Zuo Bing Du Jian-Nan Zhang Yin-Bi Li Xiao Kong Meng-Xin wang Yue Wu Ke-Fei Wu Yong-Heng Zhao Yong Zhang Yong-Hui Hou yue-fei wang Ming Yang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2015年第8期1182-1196,共15页
We present a spectroscopic catalog of 93 619 M dwarfs from the first data release of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)general survey. During sample selection, M giant contaminatio... We present a spectroscopic catalog of 93 619 M dwarfs from the first data release of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)general survey. During sample selection, M giant contamination was eliminated using2 MASS photometry and Ca H/TiO molecular indices. For each spectrum, the spectral subtype and values are provided including radial velocity, Hα equivalent width, a series of prominent molecular band indices, and the metal–sensitive parameter ζ, as well as distances and the space motions for high S/N objects. In addition, Hα emission lines are measured to examine the magnetic activity properties of M dwarfs and 7179 active ones are found. In particular, a subsample with significant variation in magnetic activity is revealed through observations from different epochs. Finally, statistical analysis for this sample is performed, including the metallicity classification, the distribution of molecular band indices and their errors. 展开更多
关键词 catalogs—methods: analytical—stars: statistical—stars late-type—stars: magnetic-activity—stars
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A comparison of stellar atmospheric parameters from the LAMOST and APOGEE datasets 被引量:1
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作者 Yu-Qin Chen Gang Zhao +9 位作者 Chao Liu Jing Ren Yun-Peng Jia Jing-Kun Zhao A-Li Luo Yue Wu Yong Zhang Yong-Hui Hou yue-fei wang Ming Yang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2015年第8期1125-1136,共12页
We have compared stellar parameters, including temperature, gravity and metallicity, for common stars in the LAMOST DR2 and SDSS DR12/APOGEE datasets. It is found that the LAMOST dataset provides a more well-defined r... We have compared stellar parameters, including temperature, gravity and metallicity, for common stars in the LAMOST DR2 and SDSS DR12/APOGEE datasets. It is found that the LAMOST dataset provides a more well-defined red clump feature than the APOGEE dataset in the Teff versus log g diagram. With this advantage, we have separated red clump stars from red giant stars, and attempt to establish calibrations between the two datasets for the two groups of stars. The results show that there is a good consistency in temperature with a calibration close to the one-to-one line, and we can establish a satisfactory metallicity calibration of[Fe/H]APOGEE= 1.18[Fe/H]LAMOST + 0.11 with a scatter of ~ 0.08 dex for both the red clump and red giant branch samples. For gravity, there is no correlation for red clump stars between the two datasets, and scatters around the calibrations of red giant stars are substantial. We found two main sources of scatter in log g for red giant stars. One is a group of stars with 0.00253 × Teff- 8.67 〈 log g 〈 2.6 located in the forbidden region, and the other is the contaminated red clump stars, which could be picked out from the unmatched region where stellar metallicity is not consistent with position in the Teff versus log g diagram. After excluding stars in these two regions,we have established two calibrations for red giant stars, log g APOGEE = 0.000615 ×Teff,LAMOST+ 0.697 × log g LAMOST- 2.208(σ = 0.150) for [Fe/H] 〉-1 and log gAPOGEE= 0.000874×Teff,LAMOST+0.588×log g LAMOST-3.117(σ = 0.167)for [Fe/H] 〈-1. The calibrations are valid for stars with Teff = 3800- 5400 K and log g = 0- 3.8 dex, and are useful in work aiming to combine the LAMOST and APOGEE datasets in a future study. In addition, we find that an SVM method based on asteroseismic log g is a good way to greatly improve the accuracy of gravity for these two regions, at least in the LAMOST dataset. 展开更多
关键词 stars: late type—stars: fundamental parameters—stars: atmospheres—stars: abundances
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Peculiar in-plane velocities in the outer disc of the Milky Way 被引量:1
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作者 Hai-Jun Tian Chao Liu +8 位作者 Jun-Chen Wan You-Gang wang Qiao wang Li-Cai Deng Zi-Huang Cao Yong-Hui Hou yue-fei wang Yue Wu Yong-Heng Zhao 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2017年第11期45-58,共14页
We present the peculiar in-plane velocities derived from LAMOST red clump stars, which are purified and separated by a novel approach into two groups with different ages. The samples are mostly contributed around the ... We present the peculiar in-plane velocities derived from LAMOST red clump stars, which are purified and separated by a novel approach into two groups with different ages. The samples are mostly contributed around the Galactic anti-center direction so that we are able to map the radial profiles of the radial and azimuthal velocities in the outer disc. From variations of the in-plane velocities with Galactocentric radius for the younger and older populations, we find that both radial and azimuthal velocities are not axisymmetric at 8 〈 R 〈 14 kpc. The two red clump populations show that the mean radial velocity is negative within R - 9 kpc and positive beyond. This is likely because of the perturbation induced by the rotating bar. The cross-zero radius, R -9 kpc, essentially indicates the rough location of the Outer Lindblad Resonance radius. Given the circular speed of 238 km s^-1, the pattern speed of the bar can be approximated as 45 km s^-1 kpc^-1. The young red clump stars show larger mean radial velocity than the old population by about 3km s^-1 between R-9 and 12kpc. This is possibly because the younger population is more sensitive to the perturbation than the older one. The radial profiles of the mean azimuthal velocity for the two populations show an interesting U-shape, i.e. at R 〈 10.Skpc, the azimuthal velocity declines with R by about 10km s^-1, while at R 〉 10.5 kpc it increases with R to 240 - 245 km s^-1. It is not clear why the mean azimuthal velocity shows this U-shape along the Galactic anti-center direction. Moreover, the azimuthal velocity for the younger population is slightly larger than that for the older one and the difference moderately declines with R. Beyond R0-12 kpc, the azimuthal velocities for the two populations are indistinguishable. 展开更多
关键词 Galaxy: disc -- Galaxy: structure -- Galaxy: kinematics and dynamics -- Galaxy: stellar content -- stars: kinematics and dynamics
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Radio stars observed in the LAMOST spectral survey 被引量:1
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作者 Li-Yun Zhang Qiang Yue +6 位作者 Hong-Peng Lu Xian-Ming L.Han Yong Zhang Jian-Rong Shi yue-fei wang Yong-Hui Hou Zi-Huang Cao 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2017年第10期67-82,共16页
Radio stars have attracted astronomers' attention for several decades. To better understand the physics behind stellar radio emissions, it is important to study their optical behaviors. The LAMOST survey provides a l... Radio stars have attracted astronomers' attention for several decades. To better understand the physics behind stellar radio emissions, it is important to study their optical behaviors. The LAMOST survey provides a large database for researching stellar spectroscopic properties of radio stars. In this work, we concentrate on their spectroscopic properties and infer physical properties from their spectra, such as stellar activity and variability. We mined big data from the LAMOST spectral survey Data Release 2 (DR2), published on 2016 June 30, by cross-matching them with radio stars from FIRST and other surveys. We obtained 783 good stellar spectra with high signal to noise ratio for 659 stars. The criteria for selection were positional coincidence within 1.5" and LAMOST objects classified as stars. We calculated the equivalent widths (EWs) of the Ca II H&K, HS, H'7, H/3, Ha and Ca II IRT lines by integrating the line profiles. Using the EWs of the Ha line, we detected 147 active stellar spectra of 89 objects having emissions above the Ha continuum. There were also 36 objects with repeated spectra, 28 of which showed chromospheric activity variability. Furthermore, we found 14 radio stars emitting noticeably in the Ca II IRT lines. The low value of the EWs542/EWsags ratio for these 14 radio stars possibly alludes to chromospheric plage regions. 展开更多
关键词 stars: chromosphere- stars: activity -- stars: radio -- stars: spectroscopic
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A sample of galaxy pairs identified from the LAMOST spectral survey and the Sloan Digital Sky Survey 被引量:1
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作者 Shi-Yin Shen Maria Argudo-Femandez +22 位作者 Li Chen Xiao-Yan Chen Shuai Feng Jin-Liang Hou Yong-Hui Hou Peng Jiang Yi-Peng Jing Xu Kong A-Li Luo Zhi-Jian Luo Zheng-Yi Shao Ting-Gui wang Wen-Ting wang yue-fei wang Hong Wu Xue-Bing Wu Hai-Feng Yang Ming Yang Fang-Ting Yuan Hai-Long Yuan Hao-Tong Zhang Jian-Nan Zhang Yong Zhang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2016年第3期63-72,共10页
A small fraction (〈 10%) of the SDSS main galaxy (MG) sample has not been targeted with spectroscopy due to the effect of fiber collisions. These galaxies have been compiled into the input catalog of the LAMOST E... A small fraction (〈 10%) of the SDSS main galaxy (MG) sample has not been targeted with spectroscopy due to the effect of fiber collisions. These galaxies have been compiled into the input catalog of the LAMOST ExtraGAlactic Surveys and named the complementary galaxy sample. In this paper, we introduce this project and status of the spectroscopies associated with the complementary galaxies in the first two years of the LAMOST spectral survey (till Sep. of 2014). Moreover, we present a sample of 1102 galaxy pairs identified from the LAMOST complementary galaxies and SDSS MGs, which are defined as two members that have a projected distance smaller than 100 h^-01kpc and a recessional velocity difference smaller than 500 km s-1. Compared with galaxy pairs that are only selected from SDSS, the LAMOST- SDSS pairs have the advantages of not being biased toward large separations and therefore act as a useful supplement in statistical studies of galaxy interaction and galaxy merging. 展开更多
关键词 galaxies: interactions -- galaxies: groups: general
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On the LSP3 estimates of surface gravity for LAMOST-Kepler stars with asteroseismic measurements 被引量:1
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作者 Juan-Juan Ren Xiao-Wei Liu +13 位作者 Mao-Sheng Xiang Yang Huang Saskia Hekker Chun wang Hai-Bo Yuan Alberto Rebassa-Mansergas Bing-Qiu Chen Ning-Chen Sun Hua-Wei Zhang Zhi-Ying Huo Wei Zhang Yong Zhang Yong-Hui Hou yue-fei wang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2016年第3期81-90,共10页
Asteroseismology allows for deriving precise values of the surface gravity of stars. The accurate asteroseismic determinations now available for the large number of stars in the Kepler fields can be used to check and ... Asteroseismology allows for deriving precise values of the surface gravity of stars. The accurate asteroseismic determinations now available for the large number of stars in the Kepler fields can be used to check and calibrate surface gravities that are currently being obtained spectroscopically for a huge number of stars targeted by large-scale spectroscopic surveys, such as the on-going Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Galactic survey. The LAMOST spectral surveys have obtained a large number of stellar spectra in the Kepler fields. Stellar atmospheric parameters of those stars have been determined with the LAMOST Stellar Parameter Pipeline at Peking University (LSP3), by template matching with the MILES empirical spectral library. In the current work, we compare surface gravities yielded by LSP3 with those of two asteroseismic samples-- the largest Kepler asteroseismic sample and the most accurate Kepler asteroseismic sample. We find that LSP3 surface gravities are in good agreement with asteroseismic values of Hekker et al., with a dispersion of -0.2 dex. Except for a few cases, asteroseismic surface gravities ofHuber et al. and LSP3 spectroscopic values agree for a wide range of surface gravities. However, some patterns in the differences can be identified upon close inspection. Potential ways to further improve the LSP3 spectroscopic estimation of stellar atmospheric parameters in the near future are briefly discussed. The effects of effective temperature and metallicity on asteroseismic determinations of surface gravities for giant stars are also discussed. 展开更多
关键词 methods: data analysis -- stars: fundamental parameters -- stars: spectroscopic -- stars general -- stars: oscillations
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The metallicity of K giant stars along the Sagittarius streams
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作者 Hong-Bo Ren Wei-Bin Shi +4 位作者 Xu Zhang Yan-Ke Tang Yong Zhang Yong-Hui Hou yue-fei wang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2017年第7期121-128,共8页
The Large Sky-Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Data Release 3 provided 341 691 K giant stars with stellar parameters. Based on the models of Law & Majewski, we identified 252 K giant stars i... The Large Sky-Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Data Release 3 provided 341 691 K giant stars with stellar parameters. Based on the models of Law & Majewski, we identified 252 K giant stars in the leading stream associated with the Sagittarius (Sgr) dwarf galaxy. We obtained 132 K giant stars belonging to the trailing arm of Sgr using the model of Belokurov et al. We studied the metallicity distribution of member stars along the streams and found a fiat gradient in the first wrap of the leading stream, -(0.88±0.3) × 10^-3 dex/(°) in the second wrap of the leading stream and -(1.2±0.3) × 10^-3 dex/(°) in the first wrap of the trailing stream. Moreover, we obtained a combined metallicity gradient with our sample and data from the literature. We also analyzed the properties of an overdensity, which is located in the leading stream of the Sgr. 展开更多
关键词 Galaxy halo - galaxies individual (Sagittarius) - stars K giant-branch
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