期刊文献+
共找到574篇文章
< 1 2 29 >
每页显示 20 50 100
墨西哥全球尺度土壤铜地球化学背景与异常特征
1
作者 姚春彦 姜瀚涛 +5 位作者 朱意萍 郑璐 李汉武 王天刚 刘君安 Uribe Luna JESUS 《地学前缘》 北大核心 2025年第1期236-243,共8页
墨西哥是拉丁美洲经济大国和世界重要的矿业生产国。本文首次根据墨西哥全境全球尺度地球化学填图287件深层(C层)土壤组合样品铜元素含量测试结果,制作了1∶8000000 C层土壤铜地球化学图,从全球尺度角度研究了墨西哥C层土壤铜地球化学... 墨西哥是拉丁美洲经济大国和世界重要的矿业生产国。本文首次根据墨西哥全境全球尺度地球化学填图287件深层(C层)土壤组合样品铜元素含量测试结果,制作了1∶8000000 C层土壤铜地球化学图,从全球尺度角度研究了墨西哥C层土壤铜地球化学背景和空间分布特征,圈定了墨西哥铜主要地球化学异常,主要取得如下结论:(1)墨西哥全球尺度C层土壤铜含量为3.6~129.0μg/g,铜含量平均值和中位值分别为20.3和15.9μg/g,背景值为15.6μg/g。恰帕斯高原和南马德雷岛弧带构造单元中铜的中位值显著大于其他构造单元,背景值高于全境背景值。(2)墨西哥全球尺度C层土壤铜地球化学图显示,铜含量分布不均,总体呈南高北低、西高东低的格局。(3)墨西哥全球尺度C层土壤铜地球化学异常图共圈定铜地球化学异常10处,8处达到地球化学巨省规模,两处达到地球化学省规模。从铜地球化学信息和已有矿床的套合情况来看,墨西哥南部南马德雷山脉和恰帕斯山脉可能成为墨西哥铜的重要找矿远景区。 展开更多
关键词 全球尺度 土壤 地球化学背景 异常特征 墨西哥
在线阅读 下载PDF
Learning from and Applying the Experience of the"Thousand-Village Demonstration,Ten-Thousand-Village Renovation"Project to Promote the Practice and Exploration of Building Harmonious and Beautiful Villages in Gansu Province
2
作者 Hongmei WAN 《Asian Agricultural Research》 2025年第11期7-13,共7页
The No.1 Central Document of 2024 emphasizes the need to learn from and apply the experience of the"Thousand-Village Demonstration,Ten-Thousand-Village Renovation"project to paint a new picture of livable,wo... The No.1 Central Document of 2024 emphasizes the need to learn from and apply the experience of the"Thousand-Village Demonstration,Ten-Thousand-Village Renovation"project to paint a new picture of livable,workable,harmonious,and beautiful villages,thereby accelerating agricultural and rural modernization and better advancing the construction of Chinese modernization.This paper,based on elucidating the scientific connotations and logical pathways of the"Thousand-Village Demonstration,Ten-Thousand-Village Renovation"project and"harmonious and beautiful villages",analyzes the practices of building"harmonious and beautiful villages"in Gansu Province.It proposes learning from the experience of coordinated advancement in the"Thousand-Village Demonstration,Ten-Thousand-Village Renovation"project to strengthen infrastructure and public service construction;learning from the experience of adapting to local conditions to reinforce rural industrial drive and integrated development;learning from the experience of environmental optimization and shaping to accelerate the improvement of human settlements and ecological civilization construction;and learning from the experience of co-construction,co-governance,and sharing to speed up rural governance and spiritual civilization development,thereby aiding the construction of harmonious and beautiful villages in Gansu. 展开更多
关键词 "Thousand-Village DEMONSTRATION Ten-Thousand-Village Renovation" Project HARMONIOUS and BEAUTIFUL VILLAGES Gansu Practice
在线阅读 下载PDF
Co-circulation of all four DENV serotypes during 2016 outbreak in Sinaloa,Mexico:First report of DENV-4 in patients
3
作者 Annete Itzel Apodaca-Medina JoséIsrael Torres-Avendaño +5 位作者 Hipólito Castillo-Ureta Edith Hilario Torres-Montoya Sergio Alonso Durán-Pérez Lorenzo Ulises Osuna-Martínez María Elena Báez-Flores José Guadalupe Rendón-Maldonado 《Virologica Sinica》 2025年第4期680-683,共4页
Dear Editor,Dengue virus(DENV)is a positive-sense single-stranded RNA virus belonging to the Flaviviridae family,which causes dengue—a disease affecting over 400 million people annually worldwide.DENV is transmitted ... Dear Editor,Dengue virus(DENV)is a positive-sense single-stranded RNA virus belonging to the Flaviviridae family,which causes dengue—a disease affecting over 400 million people annually worldwide.DENV is transmitted through the bite of mosquitoes from the Aedes genus,primarily Aedes aegypti,and has a wide distribution in tropical and subtropical areas(de Souza et al.,2022). 展开更多
关键词 OUTBREAK Co circulation DENV Sinaloa Mexico SEROTYPES Dengue virus
原文传递
Structural stability, optical and dielectric properties of the (Ba_(1/5)Pb_(1/5)Sr_(1/5)RE_(1/5)K_(1/5))TiO_(3) high-entropy ceramic
4
作者 C.Herbert-Galarza A.Durán 《International Journal of Minerals,Metallurgy and Materials》 2025年第11期2821-2834,共14页
A high-entropy matrix with highly polarizable elements sharing a rare-earth element at the same crystallographic site was designed using the chemical formula Ba_(1/5)Pb_(1/5)Sr_(1/5)RE_(1/5)K_(1/5)TiO_(3)(BPSREKTO),wh... A high-entropy matrix with highly polarizable elements sharing a rare-earth element at the same crystallographic site was designed using the chemical formula Ba_(1/5)Pb_(1/5)Sr_(1/5)RE_(1/5)K_(1/5)TiO_(3)(BPSREKTO),where rare-earth(RE)=La,Nb,Sm,Gd,Dy,Ho,Y,and Lu.Single-phase stability was observed only in the BPSREKTO with RE=La,Nd,and Sm high-entropy compounds.The crystal structure,optical properties,and ferroelectric nature of the single-phase ceramic compounds were investigated.Elemental and structural analyses revealed that all the cations were homogeneously distributed in a global centrosymmetric cubic structure(S.G.Pm3m).Optical absorption showed that the RE=Nd compound is more photoactive in the 200-1000 nm wavelength range,unlike the RE=La,Sm high-entropy compounds.The introduction of RE elements in high-entropy ceramic(HEC)systems affects the indirect bandgap of BPSREKTO with RE=La,Nd,and Sm.It was also found that cationic disorder increases the Urbach energy,leading to a decrease in the indirect energy bandgap in the HEC compound compared to the homologue BaTiO_(3)/SrTiO_(3) single-phase.The dielectric spectra show a broad peak in the dielectric constant and dielectric loss,which are shifted in temperatures with increasing frequencies due to a relaxor ferroelectric transition typical of the diffuse phase transitions.This relaxor behavior was unexpected,because the global crystal structure was centrosymmetric,implying an increase in the number of polar nanoregions(PNRs).These PNRs coexisting with non-polar regions(NPRs)were observed using piezo-force microscopy.Furthermore,the slim polarization loop confirmed the relaxor behavior of BPSREKTO with RE=La,Nd,and Sm.These ferroelectric features make these RE-modified HEC materials good candidates for high-energy storage applications. 展开更多
关键词 high-entropy ceramics perovskite compounds optical properties dielectric properties scanning electron microscopy relaxor ferroelectrics
在线阅读 下载PDF
No change over three decades in the realized spatial niche of a salamander population living in a subterranean habitat
5
作者 Sebastiano Salvidio Andrea Costa +2 位作者 Fabrizio Oneto Giacomo Rosa Mauro Valerio Pastorino 《Current Zoology》 2025年第5期678-681,共4页
Subterranean environments are buffered from external climatic fluctuations due to the absence of light and a delayed thermal response to surface conditions(Mammola 2019).Terrestrial salamanders are often found in subt... Subterranean environments are buffered from external climatic fluctuations due to the absence of light and a delayed thermal response to surface conditions(Mammola 2019).Terrestrial salamanders are often found in subterranean habitats,but few studies have assessed the influence of climatic effects on their long-term spatial distribution and niche breadth.In this study,we investigated the variability over 29 consecutive years of the spatial niche in a terrestrial salamander population inhabiting an artificial subterranean habitat.We hypothesized that juvenile salamanders,which are typically active near cave entrances and more exposed to climatic variability and dehydration(Peterman et al.2013),would exhibit an earlier and more variable behavioral adaptation to increasing external temperatures compared to adults. 展开更多
关键词 long-term ecological research niche breadth PLETHODONTIDAE Speleomantes subterranean habitat
原文传递
Causes of heterozygosity excess:The case of Mexican populations of Populus tremuloides
6
作者 Javier Hernandez-Velasco Jose Ciro Hernandez-Díaz +13 位作者 Sergio Leonel Simental-Rodríguez Juan P.Jaramillo-Correa David S.Gernandt Jose Jesús Vargas-Hernandez Ilga Porth Roos Goessen MSocorro Gonzalez-Elizondo Matthias Fladung Cuauhtemoc Saenz-Romero Jose Guadalupe Martínez-Avalos Artemio Carrillo-Parra Eduardo Mendoza-Maya Arnulfo Blanco-García Christian Wehenkel 《Plant Diversity》 2025年第3期415-428,共14页
The presence of heterozygous individuals in a population is crucial for maintaining genetic diversity,which can positively affect fitness and adaptability to environmental changes.While inbreeding generally reduces th... The presence of heterozygous individuals in a population is crucial for maintaining genetic diversity,which can positively affect fitness and adaptability to environmental changes.While inbreeding generally reduces the proportion of heterozygous individuals in a population,polyploidy tends to increase the proportion.North American Populus tremuloides is one of the most widely distributed and ecologically important tree species in the Northern Hemisphere.However,genetic variation in Mexican populations of P.tremuloides,including the genetic signatures of their adaptation to a variety of environments,remains largely uncharacterized.The aim of this study was to analyze how inbreeding coefficient(FIS)and ploidy are associated with clonal richness,population cover,climate and soil traits in 91 marginal to small,isolated populations of this tree species throughout its entire distribution in Mexico.Genetic variables were determined using 36,810 filtered SNPs derived from genome re-sequencing.We found that FIS was approximately between 0 and e1,indicating an extreme heterozygosity excess.One key contributor to the observed extreme heterozygosity excess was asexual reproduction,although ploidy levels cannot explain this excess.Analysis of all neutral SNPs showed that asexual reproduction was positively correlated with observed heterozygosity(Ho)but negatively correlated with expected heterozygosity(He).Analysis of outlier SNPs also showed that asexual reproductionwas positively correlated with Ho and negatively correlated with He,although this latter correlation was not significant.These findings support the presence of a Meselson effect. 展开更多
关键词 Quaking aspen DIPLOID TRIPLOID Asexual reproduction Adaptation Deleterious SNPs
在线阅读 下载PDF
Environmental Impact of Cremation in Tlalmanalco,State of Mexico
7
作者 Griselda González-Cardoso Berenice Quintana-Díaz +1 位作者 Alfonso Espitia-Cabrera Lorena Morelos-García 《Journal of Environmental Science and Engineering(A)》 2025年第2期113-120,共8页
The environmental impact of combustion gas emissions during the cremation process in the municipality of Tlalmanalco,State of Mexico,was investigated.A TESTO 340 combustion analyzer was used over nine days to evaluate... The environmental impact of combustion gas emissions during the cremation process in the municipality of Tlalmanalco,State of Mexico,was investigated.A TESTO 340 combustion analyzer was used over nine days to evaluate 30 cremation services.The average emission values obtained were 84.03 g/h for NO_(2),7,050.9 g/h for SO_(2),and 46,194.4 g/h for CO.Using this data,the dispersion of these pollutants was analyzed with HYSPLIT software and compared with air quality standards.Results showed that the gases dispersed effectively in the air within 1 h,ensuring no risk to the population.However,CO emissions exceeded the limit set by the NADF-017-AIRE-2017 standard for fixed sources,while NO_(2)emissions remained below the permissible limit. 展开更多
关键词 Pollution air combustion gas emissions air quality standards
在线阅读 下载PDF
Greenhouse Gas Emissions Inventory at an Agrochemical Production Facility
8
作者 JosuéMartínez-Sánchez Griselda González-Cardoso Berenice Quintana-Diaz 《Journal of Environmental Science and Engineering(A)》 2025年第3期151-155,共5页
Climate change is a pressing global issue primarily driven by increased concentrations of GHGs(Greenhouse Gases)in the atmosphere.GHGs such as CO₂(Carbon Dioxide),CH₄(Methane),and N₂O(Nitrous Oxide)trap solar radiatio... Climate change is a pressing global issue primarily driven by increased concentrations of GHGs(Greenhouse Gases)in the atmosphere.GHGs such as CO₂(Carbon Dioxide),CH₄(Methane),and N₂O(Nitrous Oxide)trap solar radiation,contributing to global warming.This study presents a GHG emissions inventory for an agrochemical production plant based on ISO(International Organization for Standardization)14064-1:2018.Emissions from both direct(fuel combustion)and indirect(electricity consumption)sources were quantified.Results indicate that indirect emissions from electricity use account for 91%of total GHGs,while direct emissions from fossil fuel combustion contribute 9%.Electricity consumption emerged as the primary contributor to the plant’s carbon footprint. 展开更多
关键词 Emission factor greenhouse gas activity data
在线阅读 下载PDF
Green synthesis of glycolic acid through the electrocatalytic reduction of oxalic acid over black TiO_(2): An experimental and theoretical study
9
作者 Hugo Olvera-Vargas Oscar Andrés Jaramillo-Quintero +4 位作者 Luis Darío Alarcón León Orlando Castro-Ocampo Christian A.Celaya Marina E.Rincón Jesús Muñiz 《Journal of Energy Chemistry》 2025年第1期544-556,共13页
Herein,we present the electrocatalytic four-electron hydrogenation of oxalic acid into glycolic acid using black TiO_(2)as an electrocatalyst.Oxalic acid is an abundant compound found in several sources of organic was... Herein,we present the electrocatalytic four-electron hydrogenation of oxalic acid into glycolic acid using black TiO_(2)as an electrocatalyst.Oxalic acid is an abundant compound found in several sources of organic waste.The results showed a high selectivity of black TiO_(2)toward glycolic acid,with the formation of glyoxylic acid being the rate-limiting step (glyoxylic acid is the two-electron intermediate).The highest Faradaic efficiency (FE) of 69.6%±8.3% was achieved at 10.2 mA cm^(-2)in 4 h of electrolysis using an H-type cell operated at room temperature,with 50.2%±3.8% of oxalic acid conversion (degradation kinetic constant k=0.0042±0.0001 min-1),58.8%±7.0%of reaction yield and 1.2±0.18 g L-1of glycolic acid production.A theoretical model of black TiO_(2)coming from anatase TiO_(2)was implemented by introducing Ti3+defects,which gave black TiO_(2)the theoretical capability to easily transform oxalic acid into glycolic acid as experimentally observed.The reaction mechanism was supported and described in detail by density functional theory calculations,which revealed that surface Ti^(3+)states were the main catalytic sites.This is the first time that a detailed step-by-step mechanism at the atomic level has been proposed for this electrocatalytic reaction,which represents a valuable contribution to the understanding of this process of high energy/environmental interest.This is also the first time that black TiO_(2)has been used as an electrocatalyst for this sustainable process. 展开更多
关键词 Chemical energy storage Electrochemical hydrogenation Density functional theory Renewable energy Oxalic acid
在线阅读 下载PDF
Creeping permafrost in Mexico:environmental status of“Nevado”Rock Glacier,Nevado de Toluca volcano
10
作者 Víctor SOTO Kenji YOSHIKAWA +2 位作者 Rafael TORRES-OROZCO Carlos M.WELSH-RODRÍGUEZ Hugo DELGADO-GRANADOS 《Journal of Mountain Science》 2025年第9期3154-3166,共13页
In contrast to glaciological studies in Mexico,periglacial studies are very recent and limited to the analysis of the general permafrost cover in the high mountains of the country.Although some of the studies on the r... In contrast to glaciological studies in Mexico,periglacial studies are very recent and limited to the analysis of the general permafrost cover in the high mountains of the country.Although some of the studies on the reconstruction of Pleistocene glaciers in Mexico mention the existence of rock glaciers,to date no work has been done to study their physical properties or determining their state of conservation.Since rock glaciers are the most important visible indicators of mountain permafrost(along with features such as gelifluction lobes and patterned ground)and given that the“Nevado”rock glacier is the main example of its kind in Mexico,this study analyzes its internal temperature and assesses its state of conservation.The investigation was carried out by drilling and thermal monitoring of rock profiles as well as air.The results indicate that at present,the“Nevado”seems to lack permafrost inside.Although there is evidence of surface freezing during the winter months in the upper part of the rock glacier,in the lower portion it is almost unnoticed;and in both parts the internal temperature shows a tendency towards positive values as depth increases,a situation that predominates throughout the year.In addition,according to the records of the climatological station located in the lower part of the rock glacier,although the annual rainfall regime could be favorable for the formation and feeding of interstitial or segregated ice,the air temperature conditions throughout the year prevent permanent freezing.The sum of the above determines that at present the“Nevado”could be considered as an inactive and relict-type rock glacier;the presence of vegetation on the surface of the debris that make it up corroborates its inactivity. 展开更多
关键词 Ice-rich permafrost Rock glacier Nevado de Toluca creeping permafrost Glaciogenic rock glacier Periglacial environment
原文传递
Mapping bioclimatic units of Oaxaca in Mexico:A systematic assessment
11
作者 Alejandro GONZÁLEZ-PÉREZ Gustavo RAMÍREZ-SANTIAGO +4 位作者 Yuri QUIROZ-ORTUÑO Alejandro VELAZQUEZ Sara DEL RÍO Jean F.MAS Ángel PENAS 《Journal of Mountain Science》 2025年第6期2083-2097,共15页
Bioclimatic classification(WBCS),which examines the relationship between vegetation distribution and climatic variables such as precipitation and temperature,is essential for understanding the ecological dynamics.This... Bioclimatic classification(WBCS),which examines the relationship between vegetation distribution and climatic variables such as precipitation and temperature,is essential for understanding the ecological dynamics.This research focuses on producing a detailed bioclimatic map of Oaxaca,Mexico,at a spatial resolution of 30 arc-seconds,using the methodology developed by Rivas-Martínez et al.(2011).Oaxaca,characterised by its complex topography and diverse climatic conditions,provides a unique opportunity to study bioclimatic patterns in a tropical region.Using high-resolution climate data from Chelsa database,we identified and mapped different bioclimates,variants,thermotypes and ombrotypes horizons and levels of continentality within the tropical macrobioclimate.Our analysis revealed a rich diversity of bioclimatic zones,reflecting the complex interplay between Oaxaca's physical geography and its bioclimates.The results,presented in high resolution maps,highlight the spatial variability and complexity of Oaxaca's bioclimatic landscape.These findings are crucial for several applications,including biodiversity conservation,agricultural planning and climate change adaptation strategies.By providing an accurate bioclimatic classification,this study makes a significant contribution to bioclimatology and could give valuable insights into climate-vegetation relationships in tropical regions.This detailed bioclimatic map improves our understanding of the current ecological status of Oaxaca and serves as a critical tool for future environmental planning and conservation efforts.Furthermore,it could be the basis for planning in national programs that consider agriculture and forests in Mexico such as Programa Sembrando Vida(PSV). 展开更多
关键词 Bioclimatic mapping Ecological planning Isobioclimate OAXACA Tropical macrobioclimate
原文传递
蜕皮激素对大麦虫化蛹的影响 被引量:5
12
作者 姜嫄 张翌楠 +2 位作者 李志强 王福海 姜冬云 《东北林业大学学报》 CAS CSCD 北大核心 2018年第5期93-95,100,共4页
为了解决生产中大麦虫(Zophobas atratus Fab.)化蛹时间不集中以及化蛹率低等问题,测定了3种蜕皮激素添加方式对不同体型大麦虫幼虫的化蛹时间、化蛹数量、预蛹率、化蛹率、平均蛹质量、羽化率和成虫体质量的影响。结果表明:混合使用昆... 为了解决生产中大麦虫(Zophobas atratus Fab.)化蛹时间不集中以及化蛹率低等问题,测定了3种蜕皮激素添加方式对不同体型大麦虫幼虫的化蛹时间、化蛹数量、预蛹率、化蛹率、平均蛹质量、羽化率和成虫体质量的影响。结果表明:混合使用昆虫蜕皮激素原粉与每天喷洒蜕皮激素稀释液相结合的方法(试验III)效果最好,可以显著缩短集中化蛹时间,大麦虫幼虫的预蛹率、化蛹数量、化蛹率、最大蛹质量、最小蛹质量、平均蛹质量以及成虫羽化时间、羽化率均高于其他2种蜕皮激素的添加方法(P<0.05)。方法 III中分组3的预蛹率最高,均值87.4%;化蛹数量最多,均值78.7头;化蛹率87%;最大蛹质量、最小蛹质量和平均蛹质量均最大,均值分别为856.7、606.7、693.3 mg。因此,在人工饲养大麦虫作为替代寄主化蛹时,选择体质量在0.65~0.80 g的幼虫按照方法III添加蜕皮激素,能显著缩短集中化蛹时间,提高化蛹率和蛹质量。 展开更多
关键词 大麦虫 蜕皮激素 化蛹时间 化蛹数量 羽化率
在线阅读 下载PDF
Effect of MnO_4^- and silver content on electrochemical behaviour of Pb-Ag alloy anodes during potential decay periods 被引量:4
13
作者 张伟 涂常青 +2 位作者 陈艺锋 Houlachi GEORGEOS 肖利 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第7期2174-2180,共7页
The effect of MnO4- and silver content on electrochemical behaviour of five commercial Pb-Ag alloy anodes was studied in acid zinc sulphate electrolyte with and without MnO4- ions at 38 °C during potential decay ... The effect of MnO4- and silver content on electrochemical behaviour of five commercial Pb-Ag alloy anodes was studied in acid zinc sulphate electrolyte with and without MnO4- ions at 38 °C during potential decay periods. When the anodes were immersed into acid zinc sulphate electrolyte without MnO4- ions, the Pb-0.72%Ag anode entered complete passivation state in the shortest time among the five anodes, followed by anodes Pb-0.67%Ag, Pb-0.60%Ag, Pb-0.58%Ag and Pb-0.29%Ag-0.1%Ca by measurement of open circuit potential. During immersion of the anodes, MnO4 ions accelerated the passivation and increased the corrosion current density of the anodes. After immersion in zinc electrolyte with MnO4-, the anode Pb-0.72%Ag had the best corrosion resistance, followed by anodes Pb-0.67%Ag, Pb-0.60%Ag, then the close anodes Pb-0.58%Ag and Pb-0.29%Ag-0.1%Ca by the electrochemical impedance spectroscopy (EIS) analysis. 展开更多
关键词 electrochemical behaviour Pb-Ag anode permanganate ion potential decay periods zinc sulphate electrolyte
在线阅读 下载PDF
红脂大小蠹Dendroctonus valens(Coleoptera,Scolytidae)和大唼蜡甲Rhizophagus grandis(Coleoptera,Rhizophagidae)的耐寒性(英文) 被引量:9
14
作者 赵建兴 杨忠岐 Jean-Claude Gregoire 《环境昆虫学报》 CSCD 北大核心 2009年第1期20-28,共9页
红脂大小蠹Dendroctonus valensLe Conte(Red turpentine beetle,RTB)是近年来在中国爆发的入侵生物,在我国主要以老熟幼虫在油松伐桩和立木的根部越冬。室内测定昆虫的过冷却点(SCP)和短时间致死低温(LLT)是评价昆虫耐寒能力的重要方... 红脂大小蠹Dendroctonus valensLe Conte(Red turpentine beetle,RTB)是近年来在中国爆发的入侵生物,在我国主要以老熟幼虫在油松伐桩和立木的根部越冬。室内测定昆虫的过冷却点(SCP)和短时间致死低温(LLT)是评价昆虫耐寒能力的重要方法。实验结果显示,红脂大小蠹越冬幼虫的平均过冷却点为-11.98±2.55℃,是一种耐冰冻的昆虫。红脂大小蠹的过冷却点在不同地理分布区的种群间有明显差异,老熟幼虫的过冷却点明显低于低龄幼虫,在越冬前和越冬后的幼虫间没有明显差异。红脂大小蠹幼虫在冬季至少可以忍受-23.5℃的大气温度安全越冬。从2001年开始引入我国的云杉大小蠹的捕食者大唼蜡甲(Rhizophagus grandis Gyll.)幼虫的过冷却点为-18.05±2.76℃,低于红脂大小蠹所有虫态的过冷却点,说明比红脂大小蠹有更强的耐寒能力。 展开更多
关键词 红脂大小蠹 大唼蜡甲 过冷却点 天敌 生物防治
在线阅读 下载PDF
从家庭养老到社会养老:新中国70年农村养老方式变迁 被引量:46
15
作者 舒奋 《浙江社会科学》 CSSCI 北大核心 2019年第6期83-91,157,158,共11页
养老是人类社会发展中必须妥善解决的重大问题。赡养老人既是中华民族的优良传统,也是每个公民应当具有的基本道德规范和行为准则。本文通过养老方式概念界定、养老方式划分,对新中国70年来农村养老方式变迁的四个阶段进行了历史回顾和... 养老是人类社会发展中必须妥善解决的重大问题。赡养老人既是中华民族的优良传统,也是每个公民应当具有的基本道德规范和行为准则。本文通过养老方式概念界定、养老方式划分,对新中国70年来农村养老方式变迁的四个阶段进行了历史回顾和简要分析,认为农业生产方式、经济发展程度、农村社会体制、社会政策取向和家庭人口结构等要素在养老方式的形成、发展与转变中起着十分重要的作用。当前,随着城乡一体的社会养老保险制度建立和社会养老服务的快速发展,从家庭养老走向社会养老将是中国农村养老方式发展的必然选择。 展开更多
关键词 农村养老 养老方式 变迁与发展
在线阅读 下载PDF
基于Dempster-Shafer理论的查询扩展模型(英文) 被引量:1
16
作者 王明文 聂建云 《江西师范大学学报(自然科学版)》 CAS 北大核心 2005年第3期210-216,共7页
查询扩展是提高信息检索召回率的有效方法,已有许多研究者提出了诸多扩展方法,但大多数方法均是简单地把扩展的词添加到查询中.这样如若不加区分原查询词和扩充词,则扩展后的查询就可能偏离原查询的语义.该文基于Dempster-Shafer证据理... 查询扩展是提高信息检索召回率的有效方法,已有许多研究者提出了诸多扩展方法,但大多数方法均是简单地把扩展的词添加到查询中.这样如若不加区分原查询词和扩充词,则扩展后的查询就可能偏离原查询的语义.该文基于Dempster-Shafer证据理论,提出了一个查询扩展的计算模型,该模型把原始查询项看作主证据,扩展项为原始查询项的辅助证据,为了能组合这两类证据,该文给出了两个带权重的Dempster-Shafer组合规则,实验表明该方法能有效地提高检索效率. 展开更多
关键词 DEMPSTER-SHAFER理论 DEMPSTER-SHAFER证据理论 扩展模型 查询扩展 有效方法 信息检索 扩展方法 计算模型 组合规则 检索效率 召回率 原始
在线阅读 下载PDF
海洋战略性新兴产业金融支持的路径选择与政策建议 被引量:8
17
作者 李萍 《中国发展》 2018年第1期35-39,共5页
该文力图通过对中国海洋战略性新兴产业金融支持体系现状的研究,分析当前中国海洋战略性新兴产业金融支持中存在的问题,提出海洋战略性新兴产业金融支持的政策建议,对指导海洋战略性新兴产业有效利用现有金融工具、促进高新技术成果的... 该文力图通过对中国海洋战略性新兴产业金融支持体系现状的研究,分析当前中国海洋战略性新兴产业金融支持中存在的问题,提出海洋战略性新兴产业金融支持的政策建议,对指导海洋战略性新兴产业有效利用现有金融工具、促进高新技术成果的转变具有理论意义和现实意义。 展开更多
关键词 海洋 战略性新兴产业 金融支持 政策
在线阅读 下载PDF
国企思想政治工作融入中心工作:困境与路径 被引量:12
18
作者 张书林 《治理现代化研究》 2018年第3期26-33,共8页
国企思想政治工作融入中心工作,是思想政治工作的价值依托、生命力所在。当前,国企思想政治工作融入中心工作面临着诸如观念理念错位性困境、能力本领不足性困境、动力不足性困境、环境氛围不良性困境、制度安排缺位性困境等方面的现实... 国企思想政治工作融入中心工作,是思想政治工作的价值依托、生命力所在。当前,国企思想政治工作融入中心工作面临着诸如观念理念错位性困境、能力本领不足性困境、动力不足性困境、环境氛围不良性困境、制度安排缺位性困境等方面的现实困境。推进国企思想政治工作有效融入中心工作,应自觉坚持以人为本原则、共同关注原则、渐进渗透原则、利益主导原则、有的放矢原则等原则要求。深化国企思想政治工作融入中心工作,在路径选择上应围绕"树立思想政治工作融入中心工作的正确理念、提高思想政治工作融入中心工作的本领、找准思想政治工作融入中心工作的切入点和突破口、营造思想政治工作融入中心工作的正气氛围、建构思想政治工作融入中心工作的制度安排"等基本面展开。 展开更多
关键词 国有企业 思想政治工作 中心工作 困境 路径
在线阅读 下载PDF
加强和创新社会治理的新思路与新举措 被引量:10
19
作者 向春玲 《治理现代化研究》 2018年第3期84-89,共6页
根据当前国际国内新形势,加强和创新社会治理已经成为推进我国治理体系和治理能力现代化的一项重要战略。本文探讨了社会治理的基本含义以及当前存在的突出问题,重点从党的十九大报告的新要求,探讨加强和创新社会治理的新思路与新举措。
关键词 社会管理 社会治理 社会治理新举措
在线阅读 下载PDF
论国家治理体系和治理能力的现代化 被引量:6
20
作者 刘海涛 《治理现代化研究》 2018年第1期5-10,共6页
国家治理体系和治理能力是一个国家制度和制度执行能力的集中体现,而运用社会主义制度治理社会主义国家是中国共产党人面临的一个全新的课题。完善和发展中国特色社会主义制度,推进国家治理体系和治理能力现代化,就是运用中国特色社会... 国家治理体系和治理能力是一个国家制度和制度执行能力的集中体现,而运用社会主义制度治理社会主义国家是中国共产党人面临的一个全新的课题。完善和发展中国特色社会主义制度,推进国家治理体系和治理能力现代化,就是运用中国特色社会主义制度有效治理国家,简言之就是依法治国。实现这个目标,既要坚定中国特色社会主义制度自信,也要通过推进党的建设新的伟大工程和全面从严治党提高党的执政能力,并且通过全面深化改革完善中国特色社会主义制度。 展开更多
关键词 制度 执政党 现代化
在线阅读 下载PDF
上一页 1 2 29 下一页 到第
使用帮助 返回顶部