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Annual variation of adult survival of a south-temperate House Wren population in Argentina
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作者 Gustavo J.Fernandez Mariana E.Carro Paulo E.Llambías 《Avian Research》 SCIE CSCD 2024年第2期229-237,共9页
Identifying factors affecting the survival of individuals is essential for understanding the evolution of life-history traits and population dynamics.Despite numerous studies on this subject in north-temperate environ... Identifying factors affecting the survival of individuals is essential for understanding the evolution of life-history traits and population dynamics.Despite numerous studies on this subject in north-temperate environments,there is a lack of equivalent studies at similar latitudes in the south.Here,we used a 14-year dataset of capture,banding,and resighting to estimate the annual variation in the apparent adult survival probability of a south-temperate population of House Wrens(Troglodytes aedon bonariae).We evaluated temporal variation in sur-vival and the effect of environmental(climatic)and demographic variables(adult abundance,total number of fledglings produced during each breeding season)on survival estimators.We found that the probability of adult survival decreased as the abundance of breeding adults increased.This density-dependent effect could be related to the resident lifestyle of southern House Wrens,which could determine an intense competition for territories and resources that ultimately would affect their survival. 展开更多
关键词 annual variation CJS DENSITY-DEPENDENCE SURVIVAL Troglodytes aedon bonariae
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The changes in the annual distribution of mountain runoff during the period of 1965-2018 in Hexi Corridor,Northwest China
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作者 Yan Luo ZhiXiang Lu +2 位作者 Qi Feng Meng Zhu JinBo Zhang 《Research in Cold and Arid Regions》 CSCD 2024年第2期73-83,共11页
The annual distribution characteristics of river runoff in arid regions have significant implications for water resource stability and management.Based on the mountain runoff data from 1965 to 2018,this study examines... The annual distribution characteristics of river runoff in arid regions have significant implications for water resource stability and management.Based on the mountain runoff data from 1965 to 2018,this study examines the annual change characteristics of monthly runoff of the Shiyang River Basin,Heihe River Basin,and Shule River Basin in the Hexi Corridor,Northwest China.Many indexes are used and analyzed,including the coefficient of variance,the complete regulation coefficient,the concentration degree and concentration period,the magnitude of change,the skewness coefficient,and the kurtosis coefficient of the annual distribution curves.The results reveal the following:(1)The inhomogeneity of annual runoff distribution in the Taolai River and the rivers to the west of it,except the Shiyou River,show an increasing trend.Conversely,the inhomogeneity of the rivers to the east of the Taolai River generally show a downward trend,but the coefficient of variance value is still very high.(2)In the Shiyang River Basin,the annual distribution of the concentration period is characterized by a relatively discrete pattern.Conversely,the Heihe River Basin exhibits a relatively concentrated pattern,and the distribution pattern of the Shule River Basin is quite different.Notably,all concentration periods in the three basins have shifted backward after the 2000s.(3)The Shiyang River Basin exhibits disordered annual distribution curves of runoff in different years.In contrast,the Heihe River Basin presents a typical‘single-peak’pattern with a prominent right-skewed.The Shule River Basin has regular distribution curves,with a gradually significant‘double-peak’pattern from east to west.Overall,there has been a slight change in runoff in the Shiyang River Basin,while the Heihe River Basin and Shule River Basin have experienced significant increases in runoff.The annual distribution curves of runoff in the Liyuan River and the rivers to the east of it exhibit a gentle peak pattern,and the appearance probability of extreme runoff during the year is low.Conversely,the rivers to the west of the Liyuan River,excluding the Danghe River,display a sharp peak and thick tail pattern,indicating that the appearance probability of extreme runoff during the year is high.These findings have practical implications for the planning and management of water resources in the Hexi Corridor.Moreover,they provide a solid foundation for predicting future changes in regional water resources. 展开更多
关键词 Hexi Corridor Inland rivers Mountain runoff annual distribution characteristics of runoff
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Fragipan Horizon Changes Using Annual Ryegrass and Other Admendments
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作者 Lloyd Murdock Anastasios Karathanasis +2 位作者 Dottie Call Dana L. Dinnes Amitava Chatterjee 《Open Journal of Soil Science》 2024年第6期388-397,共10页
A greenhouse experiment was conducted involving intact fragipan soil cores of 50 cm thickness after removing the topsoil horizons. The cores were maintained in moist condition throughout the experiment and received se... A greenhouse experiment was conducted involving intact fragipan soil cores of 50 cm thickness after removing the topsoil horizons. The cores were maintained in moist condition throughout the experiment and received several treatments with various amendments for different periods ranging from 9 to 17 months. The amendments included annual ryegrass or Festulolium residues, powder limestone and various humate compounds alone or in combination with the grass residues. The results suggested a significant effect of ryegrass and Festulolium in reducing penetration resistance into the top 10 cm of the fragipan within 9 - 17 months, particularly when used in combination with certain humate materials such as Leonardite. Apparently, this is the result of the release of certain soluble organic compounds from the plant residues or the humate amendments that increase the solubility of Si and Al associated with the fragipan brittleness, thus decreasing the density of the compacted fragipan material. 展开更多
关键词 Fragipan Fragipan Horizon Fragipan Soils Changing the Fragipan annual Ryegrass Changes Fragipan Festulolium Changes Fragipan Amendments That Change the Fragipan
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Analysis of the Prevalence Characteristics of Lung Nodules and Their Influencing Factors in The Health Check-Up Population
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作者 Fen Yang Meijuan Ma 《Journal of Clinical and Nursing Research》 2024年第4期208-212,共5页
Objective: To study the prevalence characteristics of pulmonary nodules and their influencing factors in the health check-up population. Methods: A total of 500 cases of health checkups were selected for the data stud... Objective: To study the prevalence characteristics of pulmonary nodules and their influencing factors in the health check-up population. Methods: A total of 500 cases of health checkups were selected for the data study to analyze the detection and prevalence characteristics of pulmonary nodules. The influencing factors between the pulmonary nodules group and the no pulmonary nodules group were analyzed. Results: A total of 209 cases were detected, of which there were more males than females, and for female patients, the detection rate increased with age (P < 0.05). The distribution of gender, age, smoking, respiratory symptoms, and exposure to kitchen fumes between the two groups was compared (P < 0.05). The multifactorial analysis concluded that risk factors include, respiratory symptoms, older age, exposure to kitchen fumes, and smoking. In addition, patients who exercised more had a lower risk of developing lung nodules. Conclusion: The detection rate of pulmonary nodules was high in the health check-up population and the influencing factors analyzed involved the presence of respiratory symptoms, older age, kitchen fume exposure, and smoking, while the positive influencing factor was increased exercise. 展开更多
关键词 Health check-up population Pulmonary nodules Prevalence characteristics Influencing factors
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Investigation and Analysis of Lung Cancer Risk Factors in the Health Check-Up Population
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作者 Meijuan Ma Fen Yang 《Journal of Clinical and Nursing Research》 2024年第4期203-207,共5页
Objective: To investigate and analyze the risk factors of lung cancer in the population of health checkups. Methods: A total of 500 cases of the health check-up population were selected for data study. Surveyed showed... Objective: To investigate and analyze the risk factors of lung cancer in the population of health checkups. Methods: A total of 500 cases of the health check-up population were selected for data study. Surveyed showed that 19 cases of lung cancer were grouped as the lung cancer group and the remaining 481 cases made up the control group, and the risk factors were analyzed. Results: Among men, there was a significant proportion of individuals aged 60-69 years old, and women aged 30-39 years old. Additionally, individuals aged 60 and above were at increased risk of developing lung cancer. The results of the multifactorial analysis were that the risk factors affecting the detection of lung cancer in healthy people were smoking history, family history of lung cancer, secondhand smoke, history of respiratory diseases, psychosomatic factors, living environment, and kitchen fumes. Conclusion: People over 60 years of age were prone to early lung cancer, followed by individuals aged 30-39 years. It is important to identify the risk factors of lung cancer to strengthen the screening of high-risk groups for early detection and treatment. 展开更多
关键词 Health check-up population Lung cancer Risk factors SURVEY
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Annual check-ups for overseas funded firms Will Begin March 1st
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《China's Foreign Trade》 2002年第2期52-52,共1页
关键词 annual check-ups for overseas funded firms Will Begin March 1st
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Histology, physiology, and transcriptomic and metabolomic profiling reveal the developmental dynamics of annual shoots in tree peonies (Paeonia suffruticosa Andr.)
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作者 Ningning Tong Qingyan Shu +2 位作者 Baichen Wang Liping Peng Zheng’an Liu 《Horticulture Research》 SCIE CSCD 2023年第9期68-84,共17页
The development of tree peony annual shoots is characterized by“withering”,which is related to whether there are bud points in the leaf axillaries of annual shoots.However,the mechanism of“withering”in tree peony ... The development of tree peony annual shoots is characterized by“withering”,which is related to whether there are bud points in the leaf axillaries of annual shoots.However,the mechanism of“withering”in tree peony is still unclear.In this study,Paeonia ostii‘Fengdan’and P.suffruticosa‘Luoyanghong’were used to investigate dynamic changes of annual shoots through anatomy,physiology,transcriptome,and metabolome.The results demonstrated that the developmental dynamics of annual shoots of the two cultivars were comparable.The withering degree of P.suffruticosa‘Luoyanghong’was higher than that of P.ostii‘Fengdan’,and their upper internodes of annual flowering shoots had a lower degree of lignin deposition,cellulose,C/N ratio,showing no obvious sclerenchyma,than the bottom ones and the whole internodes of vegetative shoot,which resulted in the“withering”of upper internodes.A total of 36 phytohormone metabolites were detected,of which 33 and 31 were detected in P.ostii‘Fengdan’and P.suffruticosa‘Luoyanghong’,respectively.In addition,302 and 240 differentially expressed genes related to lignin biosynthesis,carbon and nitrogen metabolism,plant hormone signal transduction,and zeatin biosynthesis were screened from the two cultivars.Furtherly,36 structural genes and 40 transcription factors associated with the development of annual shoots were highly co-expressed,and eight hub genes involved in this developmental process were identified.Consequently,this study explained the developmental dynamic on the varied annual shoots through multi-omics,providing a theoretical foundation for germplasm innovation and the mechanized harvesting of tree peony annual shoots. 展开更多
关键词 harvesting annual DYNAMICS
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Detecting Climate Change Trend, Size, and Change Point Date on Annual Maximum Time Series Rainfall Data for Warri, Nigeria
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作者 Masi G. Sam Ify L. Nwaogazie +2 位作者 Chiedozie Ikebude Chigozie Dimgba Diaa W. El-Hourani 《Open Journal of Modern Hydrology》 2023年第3期165-179,共15页
The study focused on the detection of indicators of climate change in 24-hourly annual maximum series (AMS) rainfall data collected for 36 years (1982-2017) for Warri Township, using different statistical methods yiel... The study focused on the detection of indicators of climate change in 24-hourly annual maximum series (AMS) rainfall data collected for 36 years (1982-2017) for Warri Township, using different statistical methods yielded a statistically insignificant positive mild trend. The IMD and MCIMD downscaled model’s time series data respectively produced MK statistics varying from 1.403 to 1.4729, and 1.403 to 1.463 which were less than the critical Z-value of 1.96. Also, the slope magnitude obtained showed a mild increasing trend in variation from 0.0189 to 0.3713, and 0.0175 to 0.5426, with the rate of change in rainfall intensity at 24 hours duration as 0.4536 and 0.42 mm/hr.year (4.536 and 4.2 mm/decade) for the IMD and the MCIMD time series data, respectively. The trend change point date occurred in the year 2000 from the distribution-free CUSUM test with the trend maintaining a significant and steady increase from 2010 to 2015. Thus, this study established the existence of a trend, which is an indication of a changing climate, and satisfied the condition for rainfall Non-stationary intensity-duration-frequency (NS-IDF) modeling required for infrastructural design for combating flooding events. 展开更多
关键词 Climate Change annual Maximum Series Statistical Test Rainfall Trend and Size Change Point Date
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The Inter-Annual Variability of Rainfall Onset and Its Implication on Crop Planting in Selected East Africa Countries
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作者 Isack Baliyendeza Yonah Philemon Henry King’uza +3 位作者 Ladislaus Benedict Chang’a Mecklina Merchades Babyegeye Henry Fatael Mahoo Agnes Lawrence Kijazi 《American Journal of Climate Change》 2023年第2期268-291,共24页
The inter-annual variability of rainfall onset and crop replanting in East Africa (EA) was assessed using daily estimated rainfall data from climate hazard group infrared precipitation (CHIRPS Ver2.0) and monthly Sea ... The inter-annual variability of rainfall onset and crop replanting in East Africa (EA) was assessed using daily estimated rainfall data from climate hazard group infrared precipitation (CHIRPS Ver2.0) and monthly Sea Surface Temperature (SST) indices [Indian Ocean Dipole (IOD) and El-Ni?o Southern Oscillation (ENSO) at NINO3.4 region] from the National Center for Environmental Prediction (NCEP) and the National Center for Atmospheric Research (NCAR). The data covered a period of 40 years from1981 to 2020. The methods of cumulative of daily mean rainfall, percentage of onset date departure (PODD), Mann-Kendall (MK) trend test, student t-test, and correlation were applied in the analysis. The results showed that early onset with dry spell (WDS) consideration frequently occurs in Uganda between the first and second dekads of September, while late rainfall onset WDS occurs in the first and second dekads of December over central and Northern Kenya as well as in the Northeastern highlands, parts of the northern coast and unimodal regions in Tanzania. Rainfall onset with no dry spell (WnDS) portrayed an average of 10 days before the occurrence of true onset WDS, with maximum onset departure days (ODD) above 30 days across the Rift Valley area in Kenya and the Northeastern highlands in Tanzania. The high chance of minimum ODD is seen over entire Uganda and the area around Lake Victoria. However, few regions, such as Nakuru (Kenya) Gulu and Kibale (Uganda), and Gitega (Burundi), revealed a slight positive linear trend while others showed negative trend. Significant positive patterns for correlation between onset WDS and SST indices (IOD and NINO 3.4) were discovered in Northern and Northeastern Kenya, as well as areas along the Indian Ocean (over Tanzania’s Northern Coast). Inter-annual relationship between onset dates WDS and IOD (NINO3.4) indices exhibits a high correlation coefficient r = 0.23 (r = 0.48) in Uganda and r = 0.44 (r = 0.36) in Kenya. On the other hand, a negative correlation was revealed over Burundi and Tanzania (over a unimodal region). A high percentage of PODD was observed, ranging from 40% to 70% over the Rift Valley in Kenya and at the Northeastern highlands in Tanzania. However, a strong PODD above 70% was observed over Tanga and the Northern Pwani Region in Tanzania. These findings will help farmers to understand the appropriate time for crop planting, as well as help other socio-economic activities that strongly depend on rainfall. 展开更多
关键词 Inter-annual Variability Rainfall Onset Crop Planting East Africa
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基于第十三代国际地磁参考场模型在中国区域特征分析与研究
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作者 张秀玲 赵旭东 《地震学报》 CSCD 北大核心 2024年第1期120-128,共9页
根据最新的第十三代国际地磁参考场模型(IGRF13),计算了2015—2020年中国区域地磁场模型七要素长期变化速率,并在此基础上分析我国区域地磁场长期变化特征。通过分析计算我国28个地磁台的IGRF13模型值与实际地磁场的长期变化速率、差值... 根据最新的第十三代国际地磁参考场模型(IGRF13),计算了2015—2020年中国区域地磁场模型七要素长期变化速率,并在此基础上分析我国区域地磁场长期变化特征。通过分析计算我国28个地磁台的IGRF13模型值与实际地磁场的长期变化速率、差值及均方误差,结果显示:IGRF13模型所显示的地磁场长期变化与我国区域地磁场实际观测变化基本一致,但在局部区域也存在差异,IGRF13模型能够体现中国区域地磁场的特征。应用IGRF13模型数据时需要考虑局部区域与台站实际观测数据的误差。 展开更多
关键词 地磁参考场模型 等变线 平均年变率 长期变化速率 均方根误差
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基于地球河流扇预测模型的火星地表水径流量预测
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作者 张元福 张森 +5 位作者 黄云英 孙世坦 袁晓冬 王敏 张晓晗 陈冬 《沉积学报》 CAS CSCD 北大核心 2024年第1期52-63,共12页
【目的】火星表面的水活动地质历史一直是科学界关心的热点,直接影响着火星探测的研究方向。【方法】根据火星和地球的可对比性,建立了融合345个地球现代河流扇沉积的数据集并形成了高精度扇体面积预测模型,从而识别火星上的河流扇沉积... 【目的】火星表面的水活动地质历史一直是科学界关心的热点,直接影响着火星探测的研究方向。【方法】根据火星和地球的可对比性,建立了融合345个地球现代河流扇沉积的数据集并形成了高精度扇体面积预测模型,从而识别火星上的河流扇沉积,预测火星河流扇发育期的地表水径流量。【结果】结果表示,在火星南部高地霍尔顿陨石坑附近识别出一个面积约84.35 km^(2)的典型河流扇沉积,并反向预测出该扇体形成需要的年平均地表水径流量为1.8828×10^(6)m^(3),推测出该区域径流量不是由单一降水构成,为雪山(冰川)融水和降水多种来源。【结论】该成果是河流扇研究在行星沉积学中的应用,为进一步深入研究火星和其他天体地表水活动提供了新的方法。 展开更多
关键词 火星 水活动 河流扇 沉积体系 年径流量
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OSCE在儿科规培年度考核的应用
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作者 吴爱民 虞雄鹰 +2 位作者 艾凌云 吴崇军 张帆 《中国中医药现代远程教育》 2024年第17期191-193,共3页
目的探讨客观结构化临床考试(OSCE)在儿科住院医师规范化培训(以下简称“规培”)年度考核中的应用价值。方法选取2018年一、二年级规培学员67人及2019年二、三年级规培学员67人(与2018年相同的规培学员、只是年级产生变化)。设2018年一... 目的探讨客观结构化临床考试(OSCE)在儿科住院医师规范化培训(以下简称“规培”)年度考核中的应用价值。方法选取2018年一、二年级规培学员67人及2019年二、三年级规培学员67人(与2018年相同的规培学员、只是年级产生变化)。设2018年一年级规培学员为A组、二年级规培学员为B组,那么2019年二年级规培学员为A组、三年级规培学员为B组。对2018年及2019年A组、B组规培学员进行OSCE年度考核,进行成绩分析、问卷调查并开展点评会。结果2018年A组学员各站成绩及考试总成绩低于2018年B组学员,差异有统计学意义(P<0.05),2019年A组学员总成绩较2018年A组明显提升,差异有统计学意义(P<0.05);2019年A组总成绩和2019年B组比较,差异有统计学意义(P<0.05),2019年B组总成绩与2018年B组比较,差异有统计学意义(P<0.05)。考官及学员对OSCE考核形式100%满意,各考站设置合理,试卷难易程度适度;带教老师及规培管理人员100%肯定点评会发现教学及管理工作中的不足之处。结论规培学员低年级学习成绩提升速度最快、高年级能达到规培标准,OSCE在年度考核中的应用可以全面考查学员本年度专业知识及临床实践操作的掌握情况,同时也可以综合测评基地规培管理及临床带教工作,值得推广应用。 展开更多
关键词 客观结构化临床考试 儿科学 年度考核 住院医师 规范化培训
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“妃子笑”荔枝高产若干生长发育性状
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作者 苏钻贤 黄姜 +3 位作者 申济源 张荣 万志远 陈厚彬 《中国南方果树》 北大核心 2024年第1期110-119,共10页
“妃子笑”荔枝是我国栽培区域最广的荔枝品种,比较研究不同区域“妃子笑”生长发育特性可为树冠、养分管理和成花着果调控及区域适应性发展等参考,为荔枝品种制订高产和克服“大小年”技术方案提供借鉴。2008—2022年,调查统计华南六省... “妃子笑”荔枝是我国栽培区域最广的荔枝品种,比较研究不同区域“妃子笑”生长发育特性可为树冠、养分管理和成花着果调控及区域适应性发展等参考,为荔枝品种制订高产和克服“大小年”技术方案提供借鉴。2008—2022年,调查统计华南六省(区)北纬18°32′~28°47′的24县(区)39个示范园“妃子笑”物候期;于始花期调查海南、广东、广西和云南省(区)18个果园“妃子笑”结果树枝条、叶片和花穗生长量,并取样分析枝条、叶片、花穗主要养分含量,计算植株不同部位营养需求量。结果表明,主产区“妃子笑”末次秋梢成熟期8月下旬至11月中旬,现“白点”(花穗原基)期11月下旬至翌年2月中旬,盛花期2月上旬至4月上旬,果实成熟期4月下旬至7月底。3次秋梢生长分别约为35.9、39.5和40.2 d,秋梢老熟至现花穗原基(花诱导)约87 d,花穗与花芽分化期约56 d,果实发育期约需63 d。海南等地区“妃子笑”采果后树冠重回缩修剪至1.5 m高,形成矮化树形,而粤西等地修剪至2~3 m高,塑造高大树形。“妃子笑”结果植株采果后秋梢生长1~3次,树冠表面积的平均枝梢数16条/m2,秋梢平均长度37.7 cm,秋梢复叶数17片、叶片数104片。“妃子笑”单株不同部位年生长量,以鲜质量计分别为秋梢枝条16.8 kg,叶片40.2 kg,花穗17.2 kg;以干质量计为秋梢枝条9.50 kg,叶片23.24kg,花穗7.19kg。主要养分含量为秋梢枝条中氮0.76%、磷0.26%、钾0.72%、钙0.54%、镁0.15%;叶片中氮1.79%、磷0.17%、钾0.94%、钙0.77%、镁0.25%;花穗中氮2.20%、磷0.30%、钾1.74%、钙0.32%、镁0.29%。单株50 kg的产量,年度枝叶、花穗和果实生长所需主要元素为氮0.70 kg、磷0.10 kg、钾0.46 kg,秋梢期氮、磷、钾用量分别占比全年用量的71.4%、70.0%、63.0%。从多年产量稳定性看,海南省陵水县、琼海市、海口市,广西北海铁山港区、合浦县,广东省廉江市等地是“妃子笑”适应性表现较好的栽培区。综合而言,随着纬度北移和海拔升高,“妃子笑”物候期延后,果实成熟期持续3个月以上;各地区“妃子笑”物候期相差较大的是末次秋梢成熟期和果实成熟期,差异较小的是花芽诱导期;枝叶养分需求较大,确保秋梢生长量是支撑产量和品质的重要基础。 展开更多
关键词 “妃子笑”荔枝 物候期 高产 年生长量 氮磷钾
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断层虚位错模式揭示的2022年1月8日青海门源M_(S)6.9地震前的地电阻率变化
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作者 李新艳 解滔 +3 位作者 曾宪伟 卫定军 崔瑾 李霞 《地震学报》 CSCD 北大核心 2024年第2期292-306,共15页
选取2022年1月8日青海门源M_(S)6.9地震震中400 km范围内四个地电阻率观测台站的观测精度高、具有稳态年变、震前无显著干扰的地电阻率ρ_(s)观测数据,结合ERA5同化数据集中的多层土壤温度和土壤水分含量,在利用多项式拟合获取各台站(... 选取2022年1月8日青海门源M_(S)6.9地震震中400 km范围内四个地电阻率观测台站的观测精度高、具有稳态年变、震前无显著干扰的地电阻率ρ_(s)观测数据,结合ERA5同化数据集中的多层土壤温度和土壤水分含量,在利用多项式拟合获取各台站(或测道)地电阻率正常年动态的基础上,分析了门源地震前地电阻率的异常变化。结果显示:金银滩台EW测道、武威台NS测道和山丹台EW测道、N45°W测道震前存在超阈值的异常变化,并呈现各向异性特征。基于断层虚位错模式分析了地电阻率异常变化与孕震过程之间的联系,结果表明:金银滩台震前处于压缩区并受到NNE方向的挤压,与主压应变近似正交的EW测道于震前10个月出现负异常;同样位于压缩区的武威台,受到了ENE向的挤压,NS测道的地电阻率在孕震早期(震前13个月)以负异常为主,孕震中晚期(震前3个月)出现了正异常;山丹台,位于膨胀区,受到近似NS向的拉张,与主张应变平行的NS测道未发现异常,但EW测道震前一年地电阻率出现正异常,N45°W测道的地电阻率也在震前半年左右出现超阈值并呈正异常。此外,金银滩台、山丹台和武威台距离门源地震震中的距离分别为92 km,113 km和139 km,相应的地电阻率异常最大变化幅值分别为−3.0σ,2.2σ和−2.1σ。此外,门源地震前地电阻率异常变化的时空特征与岩石实验结果及理论模型一致,也符合震源区应力应变积累程度较高、向外围方向逐渐衰减的分布特征。由此推断,2022年门源M_(S)6.9地震前地电阻率的时空变化可能与区域介质变形及应力变化有关。 展开更多
关键词 地电阻率 土壤水分含量 土壤温度 虚位错模式 年变化
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董事会非正式层级如何影响管理层年报语调操纵?
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作者 贺宏 熊健 史璐寒 《经济与管理研究》 CSSCI 北大核心 2024年第8期125-144,共20页
非正式层级是董事会发挥监督及治理作用的隐性因素,而这一隐性治理机制对于年报文本信息披露的影响及作用机理仍鲜有研究。本文利用2010—2021年沪深A股非金融上市公司数据,在理论分析的基础上实证检验董事会非正式层级对管理层年报文... 非正式层级是董事会发挥监督及治理作用的隐性因素,而这一隐性治理机制对于年报文本信息披露的影响及作用机理仍鲜有研究。本文利用2010—2021年沪深A股非金融上市公司数据,在理论分析的基础上实证检验董事会非正式层级对管理层年报文本语调操纵的影响。研究结论表明:更为清晰的非正式层级有助于董事会高效行使治理与监督职能,进而能够对管理层操纵年报文本语调发挥抑制效应;从作用机理上看,抑制效应可能通过协调代理关系、增强披露意愿及扩大资源掌控等作用路径得以实现;此外,从横截面检验结果看,抑制效应因受到来自董事会及企业特质层面的一系列异质性因素影响而呈现出差异化表现。 展开更多
关键词 董事会非正式层级 年报文本 管理层年报语调操纵 文本信息披露 董事会治理
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黄土高原径流侵蚀功率输沙模型的改进
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作者 于坤霞 李天毅 +4 位作者 贾路 李占斌 李鹏 丛佩娟 李斌斌 《农业工程学报》 EI CAS CSCD 北大核心 2024年第10期107-116,共10页
水土流失对流域生态危害严重,输沙量模拟和预测可以为流域水土流失防治提供依据,因此精确的输沙模型是流域水土流失治理的重要工具。为了精确模拟变化环境下黄土高原年输沙量,该研究基于黄土高原19个水文站的径流和输沙数据,通过随机森... 水土流失对流域生态危害严重,输沙量模拟和预测可以为流域水土流失防治提供依据,因此精确的输沙模型是流域水土流失治理的重要工具。为了精确模拟变化环境下黄土高原年输沙量,该研究基于黄土高原19个水文站的径流和输沙数据,通过随机森林变量重要性度量方法评估年径流侵蚀功率、淤地坝指数、淤地坝相对指数、归一化植被指数、不透水地面积等因子对流域年输沙量的影响,使用非线性最小二乘法估算年输沙模型参数,对比分析不同因子组合的年输沙模型精度,提出适用性较强的黄土高原年输沙模型,据此开展年输沙量变化贡献率分析。结果表明:1)以幂函数形式构建的仅含径流侵蚀功率单因子输沙模型精度与流域面积有显著的负相关关系,相关系数为-0.505(P<0.05),模型精度随着流域面积增大而下降,在面积大于7000 km^(2)的流域适用性较差;2)年径流侵蚀功率、淤地坝指数及不透水地面积因子组合建立的多因子年输沙模型在黄土高原适用性最佳,模型在率定期纳什效率系数平均值为0.84,均方根误差平均值为0.21亿t,在验证期纳什系数平均值为0.79,均方根误差平均值为0.27亿t。3)影响研究流域年输沙量变化的因素依次是:年径流侵蚀功率、不透水地面积和淤地坝指数。研究可以为黄土高原不同区域水土流失防治和生态治理工作提供理论支撑。 展开更多
关键词 侵蚀 径流 年输沙量 径流侵蚀功率 淤地坝指数 不透水地面积 贡献率
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一种基于多目标优化的独立微电网容量配置方法
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作者 陈君 唐秀明 苏宇生 《兵工自动化》 北大核心 2024年第9期66-72,96,共8页
针对独立型微电网容量配置存在经济成本和供电可靠性难以实现同时最优的问题,提出一种实现经济成本和供电可靠性最优的独立型微电网容量多目标优化配置方法。根据独立型风光储微电网系统中各分布式电源的机理构建风机、光伏、磷酸铁锂... 针对独立型微电网容量配置存在经济成本和供电可靠性难以实现同时最优的问题,提出一种实现经济成本和供电可靠性最优的独立型微电网容量多目标优化配置方法。根据独立型风光储微电网系统中各分布式电源的机理构建风机、光伏、磷酸铁锂电池的数学模型,以等年值投资成本为评估指标构建独立微电网经济成本模型,功率偏差为评估指标构建出基于层次分析法的独立微电网可靠性模型,使用非支配排序的多目标粒子群算法求解系统最优容量配置。算例结果表明,该方法对独立型微电网容量配置在同时实现供电可靠性和经济性上更有优越性。 展开更多
关键词 独立型微电网 多目标优化 等年值投资成本 容量优化配置
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桂西北不同林龄杉木人工林微量元素积累及年净积累量
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作者 温中林 满德强 +2 位作者 黄颖 曹继钊 何斌 《广西林业科学》 2024年第4期474-480,共7页
为探究桂西北杉木(Cunninghamia lanceolata)人工林微量元素积累及其年净积累量的变化特征,为杉木人工林丰产经营提供科学依据,以广西南丹县山口林场5、10、15和20年生杉木人工林为研究对象,对不同林龄杉木人工林5种微量元素[铁(Fe)、锰... 为探究桂西北杉木(Cunninghamia lanceolata)人工林微量元素积累及其年净积累量的变化特征,为杉木人工林丰产经营提供科学依据,以广西南丹县山口林场5、10、15和20年生杉木人工林为研究对象,对不同林龄杉木人工林5种微量元素[铁(Fe)、锰(Mn)、锌(Zn)、铜(Cu)和硼(B)]含量、积累量和年净积累量及其分配特征进行分析和比较。结果表明,在不同林龄杉木人工林乔木层中,Mn或Fe含量最高,其次为Zn含量,Cu或B含量最低。5、10、15和20年生杉木人工林微量元素积累总量分别为6.868、13.445、17.662和22.087 kg/hm^(2),其中乔木层占比分别为71.03%、85.46%、79.29%和72.34%,林下植被占比分别为15.35%、5.48%、4.97%和5.65%,凋落物占比分别为13.63%、9.06%、15.75%和22.01%;乔木层微量元素积累量增长总量表现为5~10年生(6.612 kg/hm^(2))>10~15年生(2.514 kg/hm^(2))>15~20年生(1.973 kg/hm^(2))。4个林龄林分微量元素年净积累总量分别为0.976、1.149、0.975和0.811 kg·hm^(-2)·a^(-1);Mn年净积累总量均最高,其次为Fe和Zn,Cu或B年净积累总量最低。在杉木人工林5~10年生时,可施用B、Cu和Zn肥料,促进杉木生长;在杉木人工林10~20年生时,可不用施肥。 展开更多
关键词 林龄 微量元素 积累量 年净积累量 桂西北 杉木人工林
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长期有机无机外源氮素配施作物氮肥利用率及土壤剖面氮分布特征
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作者 张珂珂 宋晓 +7 位作者 郭斗斗 郭腾飞 岳克 丁世杰 张水清 黄绍敏 李杰 刘新浩 《中国土壤与肥料》 CAS CSCD 北大核心 2024年第7期79-87,共9页
探究有机无机外源氮素配施对小麦-玉米轮作体系作物产量和土壤剖面氮素分布的影响,为华北平原潮土区合理减少氮肥使用、提高氮肥利用率和科学管理土壤氮素资源提供参考。基于28年肥料定位试验,选择不施肥(CK)、单施化肥(CF)、化肥与有... 探究有机无机外源氮素配施对小麦-玉米轮作体系作物产量和土壤剖面氮素分布的影响,为华北平原潮土区合理减少氮肥使用、提高氮肥利用率和科学管理土壤氮素资源提供参考。基于28年肥料定位试验,选择不施肥(CK)、单施化肥(CF)、化肥与有机肥配施(CFM)、化肥与秸秆配施(CFS)4个处理,分析了化肥、有机肥、秸秆作为主要外源氮素长期配施对作物可持续生产能力、氮肥利用率、施肥后效及潮土氮素剖面分布的影响。结果表明,投入外源氮素能提高作物产量,小麦季CF、CFM、CFS处理平均分别增产280.49%、276.02%、286.73%,玉米季平均分别增产160.15%、170.86%、178.45%。CF、CFM、CFS处理小麦季、玉米季产量变异系数均高于CK处理,小麦季增幅更大。小麦季CFS处理产量可持续指数最高,为66.32%,玉米季CFM、CFS处理产量可持续指数基本一致,高于CF处理。与CF处理相比,CFM、CFS处理平均氮素吸收量分别提高2.11%、4.29%。CF、CFM、CFS处理氮肥累积利用率分别为61.12%、62.91%、64.78%,后效分别为0.72%、0.90%、0.60%,化肥与有机肥配施效果高于单施化肥、化肥与秸秆配施。与CF处理相比,CFM处理0~40 cm土层土壤全氮含量提高22.08%~35.94%,碱解氮含量提高12.05%~38.17%。综上,投入外源氮素可提高作物产量和氮素吸收量、提升产量稳定性和可持续性。在小麦-玉米轮作体系下,化肥配施秸秆最有利于维持可持续生产能力。化肥与有机肥配施、化肥与秸秆配施提高了土壤氮含量。 展开更多
关键词 外源氮素 产量 氮肥利用率 氮肥累积利用率 土壤剖面氮素分布
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热泵精馏耦合吸收处理含盐氨水
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作者 杨德明 杨舒壮 +1 位作者 代志先 张宇 《化学工程》 CAS CSCD 北大核心 2024年第8期25-30,共6页
针对含盐氨水的回收与处理,利用蒸发除盐、精馏脱氨并耦合吸收制备一定浓度的氨水。采用一系列节能技术对蒸发和精馏进行计算优化,即双效蒸发与塔顶蒸汽直接压缩热泵精馏耦合吸收工艺(SchemeⅠ)、热泵蒸发与塔顶蒸汽直接压缩热泵精馏耦... 针对含盐氨水的回收与处理,利用蒸发除盐、精馏脱氨并耦合吸收制备一定浓度的氨水。采用一系列节能技术对蒸发和精馏进行计算优化,即双效蒸发与塔顶蒸汽直接压缩热泵精馏耦合吸收工艺(SchemeⅠ)、热泵蒸发与塔顶蒸汽直接压缩热泵精馏耦合吸收工艺(SchemeⅡ)和热泵蒸发与塔底闪蒸再压缩热泵精馏耦合吸收工艺(SchemeⅢ)。选用ELECNRTL电解质模型计算物系的热力学数据和相平衡数据,并以年总费用、综合能耗和热力学效率等作为工艺评价指标,对提出的以上3种处理工艺进行模拟与优化。研究结果表明,与SchemeⅠ相比,SchemeⅡ和SchemeⅢ可分别节省年总费用22.18%和31.66%;节约能耗47.56%和57.87%;而热力学效率则分别提高了8.59%和2.28%。显然,SchemeⅢ在年总费用与能耗方面更具优势,SchemeⅡ在热力学效率方面更具优势。 展开更多
关键词 含盐氨水 热泵 多效蒸发 节能 年总费用
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