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Analysis and assessment of land desertification in Xinjiang based on RS and GIS 被引量:5
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作者 LIHu wangxiaofeng GA0Yaqi 《Journal of Geographical Sciences》 SCIE CSCD 2004年第2期159-166,共8页
The land desertification in Xinjiang was monitored and analyzed based on RS and GIS techniques. Satellite data interpretation was adopted to obtain the general situation of Xinjiang’s land desertification in assistan... The land desertification in Xinjiang was monitored and analyzed based on RS and GIS techniques. Satellite data interpretation was adopted to obtain the general situation of Xinjiang’s land desertification in assistance with the sampling method and on-the-spot investigations. Related monitoring and investigations showed that Xinjiang was facing with severe wide range land desertification, and its desertified area made up 77.08% of the total monitoring area. As for land types, the desertified farmland accounted for 1.92% of the total monitoring area, desertified woodland 4%, desertified grassland 45%, and unused land 49%. Accordingly, as for desertification degrees, non-desertified land occupied 22.92%, weak desertified land 5.69%, medium-degree desertified land 16.58%, severe desertified land 33.19% and super severe desertified land 21.61%. Finally, as for inducing factors, wind-eroded desertification made up 58.23%, water-eroded desertification 8.69%, salinization desertification 6.52% and frozen-melt eroded desertification 3.64%. Xinjiang’s land desertification tended to get worse and the harnessing mission remained hard. 展开更多
关键词 土地监测 GIS 人造卫星 沙漠化 新疆 土地调查
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Early Paleozoic Magmatism and Gold Mineralization in the Northern Altun, NW China 被引量:4
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作者 CHENXuanhua wangxiaofeng +6 位作者 GeorgeGEHRELS YANGYi QINHong CHENZhengle YANGFeng CHENBailin LIXuezhi 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2004年第2期515-523,共9页
This paper discusses the relationships between granitic magmatism and gold mineralization and the exhumation history of the Dapinggou gold deposit in northern Altun, NW China based on the geochronological data, includ... This paper discusses the relationships between granitic magmatism and gold mineralization and the exhumation history of the Dapinggou gold deposit in northern Altun, NW China based on the geochronological data, including zircon U-Pb ages, Rb-Sr isochron age and 40Ar-39Ar dating and MDD modeling data. The main granitic magmatism age in this area is attained from the ID TIMS U-Pb geochronology of zircons from the Kuoshibulak granite, the biggest granite in the northern Altun area, which gives a concordant age of 443±5 Ma in the Late Ordovician. Zircon ID TIMS U-Pb geochronology of the West Dapinggou biotite granite west of the Dapinggou gold deposit gives concordant ages around 485±10 Ma, representing the early stage of Ordovician magmatism. The Rb-Sr isochron age (487±21 Ma) of 6 quartz inclusion samples from quartz veins in this gold deposit is very close to that of the West Dapinggou granite. MDD modeling of step heating 40Ar-39Ar data of K-feldspar from the same West Dapinggou biotite granite gives a rapid cooling history from 300℃ to 150℃ during 200-185 Ma. According to the age data and the geological setting of this area, we conclude that the Dapinggou gold deposit was formed at the early stage of the Early Paleozoic granitic magmatism in northern Altun, and exhumed in the Early Jurassic due to the normal faulting of the Lapeiquan detachment. The Early Paleozoic magmatism may provide heat source and produce geological fluids, which are very important for gold mineralization. Exhumation in the Mesozoic caused the uplift of the deposit towards the ground surface. 展开更多
关键词 granite zircon U-Pb chronology gold deposit Rb-Sr chronology EXHUMATION 40Ar-39Ar dating and MDD modeling northern Altun
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4-methoxy-2,6-bis(3,5-dimethylpyrazoyl)-1,3,5-triazine modified carbon paste electrode for trace Cu(Ⅱ) determination by differential pulse volt-ammetry
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作者 YANGSheng LUXiaoquan +2 位作者 XUEZhonghua FENGXiaoqiang wangxiaofeng 《Rare Metals》 SCIE EI CAS CSCD 2003年第4期250-253,共4页
A differential pulse voltammetric method was developed for the sensitive andselective determination of Cu(II) at 4-methoxy-2,6-bis(3,5-dimethylpyrazoyl)-l,3,5-triazine modifiedcarbon paste electrode in 0.05 mol/L KHC_... A differential pulse voltammetric method was developed for the sensitive andselective determination of Cu(II) at 4-methoxy-2,6-bis(3,5-dimethylpyrazoyl)-l,3,5-triazine modifiedcarbon paste electrode in 0.05 mol/L KHC_8H_4O_4 solution (pH = 4.02). The oxidation peak of Cu(II)was observed at 0.065 V(vs Ag/AgCl) by scanning the potential in positive direction. The analysisprocedure consisted of an open circuit accumulation step in stirred sample solution. It was followedby medium exchange to a clean solution and subsequently an anodic potential scan was affected toobtain the voltammetric peak. The current was proportional to the concentration of the Cu(II) ion ina range of 1 X 10^(-7) -1 X 10^(-4) mol/L for 6 min accumulation; the most of metal ions did notinterfere with the determination. The developed method was applied to Cu (II) determination incoal-ash sample, the results agreed with that of atomic adsorption spectroscopy (AAS). 展开更多
关键词 analysis chemistry 4-Methoxy-2 6-bis (3 5-dimethylpyrazoyl)-1 3 5-triazine differential pulse voltammetry copper (II)
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The Expression of Lactoferrin in BPH-EPS,BPH-free EPS and Prostate Cancer Secretion
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作者 XuKexin wangxiaofeng +1 位作者 HouShukun WangYunchun 《中华医学全科杂志》 2003年第8期16-19,共4页
Objective:To examine the expression of lactofertin(Lf) in both the expressed prostatic seeretion(EPS)of BPH patients,normal males and the secretion of prostate cancer cell lines PC-3 and DU145.The potential correlatio... Objective:To examine the expression of lactofertin(Lf) in both the expressed prostatic seeretion(EPS)of BPH patients,normal males and the secretion of prostate cancer cell lines PC-3 and DU145.The potential correlation of Lf with prostatic carcinogenesis was also investigated.Methods:Forty EPS samples obtained from 20 BPH patients and 20 normal males as well as the secretions of prostate cancer cell lines PC-3 and DU145 were subjected to two-dimensional gel electrophoresis(2-DE).Mass spectrometry was performed to confirm the nature of the expressed proteins in EPS and prostatic cancer secretion.Results:Based on the resulting electrophoretograms and the followed mass spectrometry analysis,several differentially expressed proteins were detected and the up-regulation of Lf (MW 35KDa,pI 7-7.5)in BPH-EPS,compared with BPH-free EPS,was also observed.More importantly, Lf was absent in prostate cancer cell lines PC-3 and DU145.Condusion:The results indicate Lf may be produced specifically by benign prostatic epithelium and prostate lost its Lf secretion during the process of carcinogenesis. 展开更多
关键词 前列腺癌 乳铁传递蛋白 良性前列腺增生症 挤压前列腺分泌物
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