XMM-LSS discovery of a  z= 1.22  galaxy cluster     

M. N. Bremer  I. Valtchanov  J. Willis  B. Altieri  S. Andreon  P. A. Duc  F. Fang  C. Jean  C. Lonsdale  F. Pacaud  M. Pierre  D. L. Shupe  J. A. Surace  I. Waddington 《Monthly notices of the Royal Astronomical Society》2006,371(3):1427-1434

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The role of non-thermal electrons in the hydrogen and calcium lines of stellar flares     

M.D. Ding  C. Fang 《Monthly notices of the Royal Astronomical Society》2001,326(3):943-949

There is observational evidence showing that stellar and solar flares occur with a similar circumstance, although the former are usually much more energetic. It is expected that the bombardment by high-energy electrons is one of the chief heating processes of the flaring atmosphere. In this paper we study how a precipitating electron beam can influence the line profiles of Ly α , H α , Ca  ii K and λ 8542. We use a model atmosphere of a dMe star and make non-LTE computations taking into account the non-thermal collisional rates owing to the electron beam. The results show that the four lines can be enhanced to different extents. The relative enhancement increases with increasing formation height of the lines. Varying the energy flux of the electron beam has different effects on the four lines. The wings of Ly α and H α become increasingly broad with the beam flux; change of the Ca  ii K and λ 8542 lines, however, is most significant in the line centre. Varying the electron energy (i.e. the low-energy cut-off for a power-law beam) has a great influence on the Ly α line, but little on the H α and Ca  ii lines. An electron beam of higher energy precipitates deeper, thus producing less enhancement of the Ly α line. The Ly α /H α flux ratio is thus sensitive to the electron energy.  相似文献   

封闭系统中CaCO_3在天然水中溶解或沉淀的水化学后果     

钱会  李雨新 《地球科学与环境学报》1994,(2)

文章在计算水溶液化学组份平衡分布及其ｐＨ值的基础上，分析和讨论了封闭系统中ＣａＣＯ３溶解或沉淀所引起的水化学后果，并依据计算数据和借助作图的办法得出了如下结论，即ＣａＣＯ３溶解会使水溶液ｐＨ值增大，Ｈ２ＣＯ３含量减少；相反，ＣａＣＯ３沉淀会使水溶液ｐＨ值减小，Ｈ２ＣＯ３含量增多。  相似文献   

P－350浸渍树脂分离富集Ag，Cd体系及其应用     

杨秀清  钱程 《国土资源》1996,(1)

以Ｐ－３５０吸附于ＤＡ＿（２０１）树脂上，制得了Ｐ－３５０浸渍树脂，通过柱层析法，试验了树脂吸附和解脱Ａｇ，Ｃｄ的条件和干扰离子的影响。建立了Ｐ－３５０浸渍树脂分离－富集Ａｇ，Ｃｄ体系，并应用于岩石样品分析中，效果较好。  相似文献   

香港揽胜太空影像地图集的设计与计算机制图     

钱金凯 《地球信息科学学报》2001,3(2):29-33

香港揽胜太空影像地图集是一本区域性综合地图集。作为信息时代的区域综合地图集的设计和编制,我们认为应该把重点放在对资源信息的深加工上,应用遥感技术、地理信息系统、计算机制图、电子制版与四色印刷技术,才能为政府决策部门提供区域可持续发展更加实用的信息产品。  相似文献   

云南天文台大气视宁度观测和初步探讨   总被引：1，自引：1，他引：0  

钱铜铃  李玉兰  尚琼珍  李景谦  许骏  岑学奋 《天文研究与技术》1996,(Z1)

介绍了为云南丽江高美古选址点作对比的云南天文台点的大气视宁度观测统计和结果，对观测过程中的有关问题作了初步探讨。对高美古和云南天文台的１９９５年５月和１９９５年１２月２０日观测资料作了对比，结果表明：高美古选址点的视宁度明显优于云南天文台。  相似文献   

祁连山区季节性积雪资源的气候分析^*   总被引：14，自引：0，他引：14  

陈乾  陈添宇 《地理研究》1991,10(1):24-38

本文采用1986年10月至1988年9月NOAA—9、10两颗卫星的AVHRR资料标准化后反演的积雪参量,对照祈连山区26个气象站1951—1988年逐日雪深、雪密度和积雪日数的资科,修正卫星反演的平均值。得到高分辨率多年平均雪深和雪盖频率的空间分布。从而估算出各流域平均雪储量,并与降雪量和春季融雪径流作对此分析。  相似文献   

长葛县规划区地下水化学特征及其成因分析     

孙芳  王磊  刘坤书  刘庆军 《河南国土资源》2001,(4)

本文根据长葛市规划区地下水化学分析资料 ,利用污染指数法对该区地下水化学特征及其成因进行了初步分析 ,指出该区局部地下水的总硬度、溶解性总固体、硝酸盐污染指数大于 1的原因是生活、工业废物处理不当和引用污水灌溉而引起 ,并提出了该市地下水污染治理的建议  相似文献   

Study on methods of land use dynamic monitoring at county level     

Lin-yi Li  Fang Huang  Zhao-li Liu  En-pu Wan 《中国地理科学(英文版)》2001,11(2):181-185

Remote sensing technique has played an important role in land use dynamic monitoring, but as for the land use dynamic monitoring at county level, traditional remote sensing methods such as satellite imagery visual interpretation and computer classification can not meet its demand for accuracy. The result of 1: 10 000 land use investigation map has high accuracy, but this method can not be used to dynamically monitor the land use because of its big expenses, long period and difficulty in updating data. In this paper, the characteristics of physiognomy, climate and the status of land use in Dehui County are taken into consideration and a set of method, which takes use of 3S techniques and applies to Northeast China Plain, is come up with. When the land use type of a land parcel changed as a whole, the date updating can be make by changing its land type ID in the attribute table in a GIS. When the land use type of an irregular area changed, GPS receivers are used to position its border. This set of method is characteristic of high accuracy and low expenses. It gets the information of land use change timely and can be used to dynamically monitor the land use. Foundation item: Under the auspices of the key project of the National Ninth Five-year Plan (96-B02-01-07). Biography: LI Lin-yi (1968 —), female, a native of Jilin, Ph. D. candidate of Changchun Institute of Geography, the Chinese Academy of Sciences. Her research interest includes land use change monitoring and crop yield estimation using “3S” techniques.  相似文献   

Radio Observations at 232 MHz and Multifrequency Spectral Studies of SNR HB21     

X.Z. Zhang  S.J. Qian  L.A. Higgs  T.L. Landecker  X.J. Wu 《Astrophysics and Space Science》2002,279(4):355-366

Radio observational results at 232 MHz and multifrequency studies of supernova remnant (SNR) HB21 are presented. Its integrated flux density at 232 MHz is about 390 ± 30 Jy. Both the integrated spectral index and the spatial variations of spectral index of the remnant were calculated by combining the new map at 232 MHz with previously published maps made at 408, 1420, 2695, and 4750 MHz. The SNR has an integrated spectral index of about α = -0.43(S _ν ∝ ν^α) between 232 and 4750 MHz. In general the spectral index varies from –0.5 in southeast and west regions of the remnant to –0.3 in the central region and near the northwest edge. The new data of 232 MHz reveals that there is interaction between the remnant and the surrounding gas along the east edge of the remnant which causes the spectrum flattening at low frequency, while the very good agreement between the structure of X-ray emission and the central flat spectrum area suggests that the existence of thermal emission is the reason of spectrum flattening in the area. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献