为了探究三频信标反演高精度电离层电子浓度总含量(total electron content, TEC)的理论过程并分析不同观测误差对反演精度产生的影响,通过仿真卫星信号多普勒频移的方法来进行三频信标技术反演TEC的研究.通过已知的卫星轨道坐标、接收...为了探究三频信标反演高精度电离层电子浓度总含量(total electron content, TEC)的理论过程并分析不同观测误差对反演精度产生的影响,通过仿真卫星信号多普勒频移的方法来进行三频信标技术反演TEC的研究.通过已知的卫星轨道坐标、接收站坐标、卫星高度角与电离层背景信息,利用信号传播规律,仿真得到信号传播过程中的多普勒频移信息,解算出相对TEC;再利用多站法估计相位积分常数,解算双频绝对TEC;而后利用多普勒相移小数部分与三频相位积分常数结合,解算高精度三频TEC.将反演的三频TEC值与先验背景电离层TEC值进行比对,在6°观测误差的情况下,三频反演的TEC差值相对平均值在4.5%以内,相对RMS在6%以内,结果表明三频信标技术可以有效提高TEC反演精度.展开更多
目的:系统评价棘白菌素类抗真菌药物预防侵袭性念珠菌血症的有效性及安全性,为临床治疗提供循证参考。方法:计算机检索PubMed、Embase、Medline、Cochrane图书馆、中国期刊全文数据库、中文科技期刊数据库、万方数据,检索时限为建库起至...目的:系统评价棘白菌素类抗真菌药物预防侵袭性念珠菌血症的有效性及安全性,为临床治疗提供循证参考。方法:计算机检索PubMed、Embase、Medline、Cochrane图书馆、中国期刊全文数据库、中文科技期刊数据库、万方数据,检索时限为建库起至2019年7月,收集棘白菌素类药物(试验组)对比常规抗真菌药物(两性霉素B及三唑类抗真菌药,对照组)预防侵袭性念珠菌血症有效性和安全性的随机对照试验(RCT),对符合纳入标准的临床研究进行资料提取并采用Cochrane系统评价员手册5.0.2进行质量评价后,采用Rev Man 5.2统计软件对突破性侵袭性真菌感染率、真菌感染死亡率、全因死亡率及因不良反应停药的发生率进行Meta分析。结果:共纳入7项RCT,合计3 219例患者。Meta分析结果显示,试验组患者突破性侵袭性真菌感染发生率[OR=0.58,95%CI(0.40,0.85),P=0.004]、真菌感染死亡率[OR=0.68,95%CI(0.51,0.92),P=0.01]和因不良反应停药的发生率[OR=0.52,95%CI(0.40,0.67),P<0.001]均显著低于对照组,差异均有统计学意义;两组患者全因死亡率比较,差异无统计学意义[OR=0.84,95%CI(0.67,1.05),P=0.13]。结论:与两性霉素B及三唑类抗真菌药比较,棘白菌素类药物用于预防侵袭性念珠菌血症可降低突破性侵袭性真菌感染发生率、真菌感染死亡率和因不良反应停药的发生率。展开更多
In this study Chengdu Red Earth （CRE） from the Chengdu Plain （CP）,Sichuan province,was analyzed for its elemental （major and trace elements） and isotopic （Sm-Nd） geochemistry and compared with Pleistocene loes...In this study Chengdu Red Earth （CRE） from the Chengdu Plain （CP）,Sichuan province,was analyzed for its elemental （major and trace elements） and isotopic （Sm-Nd） geochemistry and compared with Pleistocene loess and paleosol samples from the Chinese Loess Plateau （CLP） in Northern China.The geochemical composition of CRE is similar to north China loess,and also resembles the average UCC.This indicates that CRE,as loess deposits in Northern China,was derived from well-mixed sedimentary protoliths that have undergone numerous upper crustal recycling processes.However,obvious differences in the geochemical characteristics of CRE and the north China loess are also revealed in our results.For chemically stable elements,CRE has higher Ti,Zr,Hf and lower ΣREE,Ba contents in comparison with loess samples from the CLP.Further analysis shows that CRE has higher TiO2/Al2O3,SiO2/Al2O3,Ba/Rb and lower Ce/Yb,Eu/Yb,LaN/YbN and ΣLREE/ ΣHREE ratios.In Sm-Nd isotopic geochemistry,Sm and Nd content and the εNd（0） value in CRE are significantly higher than those in north China loess.The higher TiO2 content in CRE coincided with a high background concentration of Ti in the Sichuan Basin and the surrounding regions.The lower ΣREE and higher Sm,Nd,εNd（0） values are related to the wide distribution of basalt in the southwest Sichuan Basin.The elemental and isotopic geochemistry of CRE indicates that eolian materials in the CP predominantly come from the Sichuan Basin and the surrounding regions,which differs from loess deposits in the CLP.展开更多
The eolian deposits distributed in the river valleys in the eastern margin of the Tibetan Plateau （TP） are very useful in neotectonic and paleoclimatic studies. Firstly, the climate in the eastern margin of the TP i...The eolian deposits distributed in the river valleys in the eastern margin of the Tibetan Plateau （TP） are very useful in neotectonic and paleoclimatic studies. Firstly, the climate in the eastern margin of the TP is mainly controlled by the Indian summer monsoon, and detailed studies on the loess-paleosol sequences in this region can provide valuable terrestrial evidence of past changes in the Indian summer monsoon. Secondly, the river terraces in the eastern margin of the TP are considered to be a sensitive recorder of neotectonism to reflect the timing and amplitude of the TP uplift.展开更多
文摘为了探究三频信标反演高精度电离层电子浓度总含量(total electron content, TEC)的理论过程并分析不同观测误差对反演精度产生的影响,通过仿真卫星信号多普勒频移的方法来进行三频信标技术反演TEC的研究.通过已知的卫星轨道坐标、接收站坐标、卫星高度角与电离层背景信息,利用信号传播规律,仿真得到信号传播过程中的多普勒频移信息,解算出相对TEC;再利用多站法估计相位积分常数,解算双频绝对TEC;而后利用多普勒相移小数部分与三频相位积分常数结合,解算高精度三频TEC.将反演的三频TEC值与先验背景电离层TEC值进行比对,在6°观测误差的情况下,三频反演的TEC差值相对平均值在4.5%以内,相对RMS在6%以内,结果表明三频信标技术可以有效提高TEC反演精度.
文摘目的:系统评价棘白菌素类抗真菌药物预防侵袭性念珠菌血症的有效性及安全性,为临床治疗提供循证参考。方法:计算机检索PubMed、Embase、Medline、Cochrane图书馆、中国期刊全文数据库、中文科技期刊数据库、万方数据,检索时限为建库起至2019年7月,收集棘白菌素类药物(试验组)对比常规抗真菌药物(两性霉素B及三唑类抗真菌药,对照组)预防侵袭性念珠菌血症有效性和安全性的随机对照试验(RCT),对符合纳入标准的临床研究进行资料提取并采用Cochrane系统评价员手册5.0.2进行质量评价后,采用Rev Man 5.2统计软件对突破性侵袭性真菌感染率、真菌感染死亡率、全因死亡率及因不良反应停药的发生率进行Meta分析。结果:共纳入7项RCT,合计3 219例患者。Meta分析结果显示,试验组患者突破性侵袭性真菌感染发生率[OR=0.58,95%CI(0.40,0.85),P=0.004]、真菌感染死亡率[OR=0.68,95%CI(0.51,0.92),P=0.01]和因不良反应停药的发生率[OR=0.52,95%CI(0.40,0.67),P<0.001]均显著低于对照组,差异均有统计学意义;两组患者全因死亡率比较,差异无统计学意义[OR=0.84,95%CI(0.67,1.05),P=0.13]。结论:与两性霉素B及三唑类抗真菌药比较,棘白菌素类药物用于预防侵袭性念珠菌血症可降低突破性侵袭性真菌感染发生率、真菌感染死亡率和因不良反应停药的发生率。
基金supported by the National Department Public Benefit Research Foundation of China (grant no. 201211077)the Mineral Resources Investigation and Appraisal Project of the Ministry of Land and Resources (grant nos. 41212011087118 and 1212010914041)
文摘In this study Chengdu Red Earth （CRE） from the Chengdu Plain （CP）,Sichuan province,was analyzed for its elemental （major and trace elements） and isotopic （Sm-Nd） geochemistry and compared with Pleistocene loess and paleosol samples from the Chinese Loess Plateau （CLP） in Northern China.The geochemical composition of CRE is similar to north China loess,and also resembles the average UCC.This indicates that CRE,as loess deposits in Northern China,was derived from well-mixed sedimentary protoliths that have undergone numerous upper crustal recycling processes.However,obvious differences in the geochemical characteristics of CRE and the north China loess are also revealed in our results.For chemically stable elements,CRE has higher Ti,Zr,Hf and lower ΣREE,Ba contents in comparison with loess samples from the CLP.Further analysis shows that CRE has higher TiO2/Al2O3,SiO2/Al2O3,Ba/Rb and lower Ce/Yb,Eu/Yb,LaN/YbN and ΣLREE/ ΣHREE ratios.In Sm-Nd isotopic geochemistry,Sm and Nd content and the εNd（0） value in CRE are significantly higher than those in north China loess.The higher TiO2 content in CRE coincided with a high background concentration of Ti in the Sichuan Basin and the surrounding regions.The lower ΣREE and higher Sm,Nd,εNd（0） values are related to the wide distribution of basalt in the southwest Sichuan Basin.The elemental and isotopic geochemistry of CRE indicates that eolian materials in the CP predominantly come from the Sichuan Basin and the surrounding regions,which differs from loess deposits in the CLP.
基金supported by the National Department Public Benefit Research Foundation of China(grant No.201211077)National Natural Science Foundation of China(Grant No.40802033)
文摘The eolian deposits distributed in the river valleys in the eastern margin of the Tibetan Plateau （TP） are very useful in neotectonic and paleoclimatic studies. Firstly, the climate in the eastern margin of the TP is mainly controlled by the Indian summer monsoon, and detailed studies on the loess-paleosol sequences in this region can provide valuable terrestrial evidence of past changes in the Indian summer monsoon. Secondly, the river terraces in the eastern margin of the TP are considered to be a sensitive recorder of neotectonism to reflect the timing and amplitude of the TP uplift.
