In this paper we establish Levin type comparison theorems for certain second order differential equations. The results obtained here generalize and extend some of the earlier ones related to the Levin's comparison...In this paper we establish Levin type comparison theorems for certain second order differential equations. The results obtained here generalize and extend some of the earlier ones related to the Levin's comparison theorems.展开更多
In view of the problems of Yangzhongyan reservoir, such as relatively developed cracks on both sides of the dam site, steep terrain, general slope stability, and relative development of rock mass dissolution in elevat...In view of the problems of Yangzhongyan reservoir, such as relatively developed cracks on both sides of the dam site, steep terrain, general slope stability, and relative development of rock mass dissolution in elevation below the designed normal water level, the stress of the dam foundation shoulder and the stability of the dam will be poor. After site survey and exploration, the recommended type of dam is rockfill concrete arch dam, considering the treatment measures of dam foundation shoulder, slope excavation and support method, seepage control treatment method of dissolution zone, layout of key components (dam, drainage building and water collecting and releasing facilities), project investment and economic benefits, etc. The dam structure is designed according to the Design Code for Concrete Arch DAMS SL282-2018. The analysis results show THAT the stress OF dam body under various working conditions is within the allowable range stipulated in the code, and the bearing capacity of bedrock meets the requirements.展开更多
Several Au deposits in Guizhou Province,southwest China,described as being similar to the highly productive Carlin-type gold deposits in northern Nevada.USA,were examined to identify similarities and differences betwe...Several Au deposits in Guizhou Province,southwest China,described as being similar to the highly productive Carlin-type gold deposits in northern Nevada.USA,were examined to identify similarities and differences between the two districts.Samples were collected along transects from lowto high-grade rock,where possible,and fram stockpiles at the Shuiyindong,Zimudang,Taipingdong,Yata and Jinfeng(formerly Lannigou)deposits.Methods used to examine ore and alteration minerals included hand-sample description:reflectance spectroscopy using an ASD Terraspec spectrometer;analyses of hand samples by carbonate staining with Alizaren red and potassium ferricyanide;transmitted and reflected light petrography;chemical analyses,mineral identification,and imaging using a JEOL.JSM-5610 scanning electron microscope:and quantitative chemical analyses using a JEOL JXA-8900 electron probe microanalyzer.Geochemical analyses of hand samples for 52 elements were done by ALS Chemex.Results indicate both similarities and differences between the two districts.Both districts have similar geologic histories.and deposits at both locations appear to have formed as a result of similar tectonic events.though the district in southwest China lacks evidence of eoeval felsic igneous activity;however,the ore-stage minerals and the fluids that produced the minerals and deposits have some significant differences.The Nevada deposits were dominated by fluid-rock reaction in which host rock Fe was sulfidized to form Au-bearing pyrite.Although ore fluids sulfidized host rock Fe in the Cuizhou deposits.the timing of Fe metasomatism is unknown,so whether the deposits formed in response to sulfidation or pyritization is unclear.Fluid-rock reaction between an acidic,aqueous fluid and highly reactive calcareous rocks in Nevada caused extensive decarbonatization of host rocks,jasperoid replacemerit of carbonate minerals,and alteration of silty rock components to illite and kaolinite.In Guizhou,CO2-bearing ore fluids with temperatures and pressures approaching 100℃ and 500 bars greater than temperatures and pressures detemained for ore fluids in the Nevada deposits,deposited Aubearing pyrite.In examined Guizhou deposits these fluids carbonatized host rocks and farmed both replacement and open-space-filling ore.The fluids,which may have been immiscible,were sufficiently overpressured to fracture wall rocks and to create significant open space filled by vein quartz.While deposit architecture,tectonic setting,and host rocks in Guizhou are quite similar to northern Nevada,ore and alteration minerals suggest that ore-forming processes in examined Guizhou deposits have important similarities to processes associated with formation of orogenic Au systems.The Guizhou deposits display characteristics of both Carlin-type and orogenic systems,perhaps indicating formation at conditions somewhat intermediate to conditions for Carlin-type deposits and orogenic systems.展开更多
In order to research the capacity differences of road intersections,this paper analyzed the influence factors and calculation models of various types of capacity at intersections and then obtained simplified models th...In order to research the capacity differences of road intersections,this paper analyzed the influence factors and calculation models of various types of capacity at intersections and then obtained simplified models through reasonable assumption. 2 /2,4 /2,4 /4 intersections at which saturation and forecasted traffic volume were given were taken as examples,and an appropriate type was selected through capacity comparison. This paper can give a predictive estimation of the intersection capacity and provides theoretical data for the type selection of intersections.展开更多
Assessing the effects of vegetation on water and soil conversation is the key basis for research and management of ecological restoration on water-eroded areas.In this study,the runoff depth,soil loss and correspondin...Assessing the effects of vegetation on water and soil conversation is the key basis for research and management of ecological restoration on water-eroded areas.In this study,the runoff depth,soil loss and corresponding precipitation of five plots planted respectively with Pueraria lobata,Lespedeza bicolor Turcz,Manglietia yuyuanensis Law,Paspalum natatu Fliigge,Paspalum wettsteinii Hackel and one control plot were observed monthly from 2003 to 2010 in Hetian Town of Changting County,Fujian Province,a typical water-eroded area in southern China.Then the effects of different vegetation on water/soil conversation(RE/SE)were determined using the ratios of runoff depth/soil loss between vegetated plots to the control plot.Meanwhile,the effect of precipitation on the water and soil loss was also analyzed.The results showed that,both the water and soil conservation effects of Pueraria lobata and Manglietia yuyuanensis Law are better than Lespedeza bicolor Turcz and Paspalum natatu,while Paspalum wettsteinii Hackel are the worst.The differences of effects of water conservation are more significantly than those of soil conversation between five kinds of vegetations.The runoff depth is mainly affected by precipitation,the determination coefficients(R2)of linear regression models between precipitation and runoff depth of all planted plots are all greater than 0.9,whereas the determination coefficients of the linear regression models between precipitation and soil loss vary form 0.3 to 0.8 for different vegetated plots.These results provide a reference for vegetation reconstruction in the current and similar areas.展开更多
Since Carlson(1977), bare noun phrases(which willbe referred to as BNPs afterwards) have been a focus of linguistics in English. Gradually, the studies of bare noun phrase has also caught much attention in China. Desp...Since Carlson(1977), bare noun phrases(which willbe referred to as BNPs afterwards) have been a focus of linguistics in English. Gradually, the studies of bare noun phrase has also caught much attention in China. Despite of the extensive studies of BNPs in English and Chinese respectively, a systematic comparison between English and Chinese BNPs in semantic readings is still less developed. More detailed studies and comparisons are obviously desirable. Most linguists agree that the semantics of the predicates, syntactic distribution and pragmatic factors all have a role to play in determining the interpretation of BNPs. Thus the paper has systematically made a semantic comparison between English BNPs and Chinese BNPs in terms of different predicate types and different syntactic distributions following the four semantic readings of BNPs of Shen(2005), namely, generic reading, existential reading,definite reading and non-referential reading.展开更多
目的分析和比较儿科学专业学生不同阶段人格类型差异,为临床教学和儿科学高素质人才培养提供个性化教学参考。方法2019年7月至2021年7月,采用整群抽样方法,选择河北医科大学2016级“5+3”一体化儿科学专业(以下简称儿科学专业)29名学生...目的分析和比较儿科学专业学生不同阶段人格类型差异,为临床教学和儿科学高素质人才培养提供个性化教学参考。方法2019年7月至2021年7月,采用整群抽样方法,选择河北医科大学2016级“5+3”一体化儿科学专业(以下简称儿科学专业)29名学生为研究对象。采用迈尔斯-布里格斯类型指标(Myers-Briggs type indicator,MBTI)M版本的汉化版量表,对其进行阶段性人格类型测试,通过SPSS 26.0软件对相关数据进行统计学处理,分析和比较临床教学前后学生人格类型差异。结果男生临床教学前后内外向维度差异具有统计学意义(t=-0.064,P=0.949),临床教学后内向比例提升,外向比例无明显变化;临床教学前男生偏向感觉维度比例高于女生,临床教学后女生感觉维度倾向升高比例更为显著;男生偏向思考比例高于女生。经过2年临床见习和实习后,儿科学专业学生在内外向方面无显著性变化,而在接收信息方式和做出决策方式,以及对待不确定性的态度方面均实现了更为合乎逻辑和判断力的转变。结论将MBTI作为人格类型测试工具,可以较为真实地掌握儿科学专业学生的个性特征,并依据临床教学前后其人格类型的差异,总结反思临床教学方法和培养模式的优势与不足,据此针对性地“因材施教”,为进一步研究儿科医生人格与职业胜任的关系提供支撑。展开更多
文摘In this paper we establish Levin type comparison theorems for certain second order differential equations. The results obtained here generalize and extend some of the earlier ones related to the Levin's comparison theorems.
文摘In view of the problems of Yangzhongyan reservoir, such as relatively developed cracks on both sides of the dam site, steep terrain, general slope stability, and relative development of rock mass dissolution in elevation below the designed normal water level, the stress of the dam foundation shoulder and the stability of the dam will be poor. After site survey and exploration, the recommended type of dam is rockfill concrete arch dam, considering the treatment measures of dam foundation shoulder, slope excavation and support method, seepage control treatment method of dissolution zone, layout of key components (dam, drainage building and water collecting and releasing facilities), project investment and economic benefits, etc. The dam structure is designed according to the Design Code for Concrete Arch DAMS SL282-2018. The analysis results show THAT the stress OF dam body under various working conditions is within the allowable range stipulated in the code, and the bearing capacity of bedrock meets the requirements.
基金We would also like to acknowledge financial support from Key Project 40930423 from the National Natural Science Foun dation of China.
文摘Several Au deposits in Guizhou Province,southwest China,described as being similar to the highly productive Carlin-type gold deposits in northern Nevada.USA,were examined to identify similarities and differences between the two districts.Samples were collected along transects from lowto high-grade rock,where possible,and fram stockpiles at the Shuiyindong,Zimudang,Taipingdong,Yata and Jinfeng(formerly Lannigou)deposits.Methods used to examine ore and alteration minerals included hand-sample description:reflectance spectroscopy using an ASD Terraspec spectrometer;analyses of hand samples by carbonate staining with Alizaren red and potassium ferricyanide;transmitted and reflected light petrography;chemical analyses,mineral identification,and imaging using a JEOL.JSM-5610 scanning electron microscope:and quantitative chemical analyses using a JEOL JXA-8900 electron probe microanalyzer.Geochemical analyses of hand samples for 52 elements were done by ALS Chemex.Results indicate both similarities and differences between the two districts.Both districts have similar geologic histories.and deposits at both locations appear to have formed as a result of similar tectonic events.though the district in southwest China lacks evidence of eoeval felsic igneous activity;however,the ore-stage minerals and the fluids that produced the minerals and deposits have some significant differences.The Nevada deposits were dominated by fluid-rock reaction in which host rock Fe was sulfidized to form Au-bearing pyrite.Although ore fluids sulfidized host rock Fe in the Cuizhou deposits.the timing of Fe metasomatism is unknown,so whether the deposits formed in response to sulfidation or pyritization is unclear.Fluid-rock reaction between an acidic,aqueous fluid and highly reactive calcareous rocks in Nevada caused extensive decarbonatization of host rocks,jasperoid replacemerit of carbonate minerals,and alteration of silty rock components to illite and kaolinite.In Guizhou,CO2-bearing ore fluids with temperatures and pressures approaching 100℃ and 500 bars greater than temperatures and pressures detemained for ore fluids in the Nevada deposits,deposited Aubearing pyrite.In examined Guizhou deposits these fluids carbonatized host rocks and farmed both replacement and open-space-filling ore.The fluids,which may have been immiscible,were sufficiently overpressured to fracture wall rocks and to create significant open space filled by vein quartz.While deposit architecture,tectonic setting,and host rocks in Guizhou are quite similar to northern Nevada,ore and alteration minerals suggest that ore-forming processes in examined Guizhou deposits have important similarities to processes associated with formation of orogenic Au systems.The Guizhou deposits display characteristics of both Carlin-type and orogenic systems,perhaps indicating formation at conditions somewhat intermediate to conditions for Carlin-type deposits and orogenic systems.
基金Sponsored by the Natural Science Foundation of Heilongjiang Province ( Grant No. E2007-14)
文摘In order to research the capacity differences of road intersections,this paper analyzed the influence factors and calculation models of various types of capacity at intersections and then obtained simplified models through reasonable assumption. 2 /2,4 /2,4 /4 intersections at which saturation and forecasted traffic volume were given were taken as examples,and an appropriate type was selected through capacity comparison. This paper can give a predictive estimation of the intersection capacity and provides theoretical data for the type selection of intersections.
基金Supported by National Natural Science Foundation of China(41071281)
文摘Assessing the effects of vegetation on water and soil conversation is the key basis for research and management of ecological restoration on water-eroded areas.In this study,the runoff depth,soil loss and corresponding precipitation of five plots planted respectively with Pueraria lobata,Lespedeza bicolor Turcz,Manglietia yuyuanensis Law,Paspalum natatu Fliigge,Paspalum wettsteinii Hackel and one control plot were observed monthly from 2003 to 2010 in Hetian Town of Changting County,Fujian Province,a typical water-eroded area in southern China.Then the effects of different vegetation on water/soil conversation(RE/SE)were determined using the ratios of runoff depth/soil loss between vegetated plots to the control plot.Meanwhile,the effect of precipitation on the water and soil loss was also analyzed.The results showed that,both the water and soil conservation effects of Pueraria lobata and Manglietia yuyuanensis Law are better than Lespedeza bicolor Turcz and Paspalum natatu,while Paspalum wettsteinii Hackel are the worst.The differences of effects of water conservation are more significantly than those of soil conversation between five kinds of vegetations.The runoff depth is mainly affected by precipitation,the determination coefficients(R2)of linear regression models between precipitation and runoff depth of all planted plots are all greater than 0.9,whereas the determination coefficients of the linear regression models between precipitation and soil loss vary form 0.3 to 0.8 for different vegetated plots.These results provide a reference for vegetation reconstruction in the current and similar areas.
文摘Since Carlson(1977), bare noun phrases(which willbe referred to as BNPs afterwards) have been a focus of linguistics in English. Gradually, the studies of bare noun phrase has also caught much attention in China. Despite of the extensive studies of BNPs in English and Chinese respectively, a systematic comparison between English and Chinese BNPs in semantic readings is still less developed. More detailed studies and comparisons are obviously desirable. Most linguists agree that the semantics of the predicates, syntactic distribution and pragmatic factors all have a role to play in determining the interpretation of BNPs. Thus the paper has systematically made a semantic comparison between English BNPs and Chinese BNPs in terms of different predicate types and different syntactic distributions following the four semantic readings of BNPs of Shen(2005), namely, generic reading, existential reading,definite reading and non-referential reading.
文摘目的分析和比较儿科学专业学生不同阶段人格类型差异,为临床教学和儿科学高素质人才培养提供个性化教学参考。方法2019年7月至2021年7月,采用整群抽样方法,选择河北医科大学2016级“5+3”一体化儿科学专业(以下简称儿科学专业)29名学生为研究对象。采用迈尔斯-布里格斯类型指标(Myers-Briggs type indicator,MBTI)M版本的汉化版量表,对其进行阶段性人格类型测试,通过SPSS 26.0软件对相关数据进行统计学处理,分析和比较临床教学前后学生人格类型差异。结果男生临床教学前后内外向维度差异具有统计学意义(t=-0.064,P=0.949),临床教学后内向比例提升,外向比例无明显变化;临床教学前男生偏向感觉维度比例高于女生,临床教学后女生感觉维度倾向升高比例更为显著;男生偏向思考比例高于女生。经过2年临床见习和实习后,儿科学专业学生在内外向方面无显著性变化,而在接收信息方式和做出决策方式,以及对待不确定性的态度方面均实现了更为合乎逻辑和判断力的转变。结论将MBTI作为人格类型测试工具,可以较为真实地掌握儿科学专业学生的个性特征,并依据临床教学前后其人格类型的差异,总结反思临床教学方法和培养模式的优势与不足,据此针对性地“因材施教”,为进一步研究儿科医生人格与职业胜任的关系提供支撑。
