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基于LV-DBSCAN算法的大坝安全监测数据异常检测 被引量:4
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作者 戴领 李少林 +2 位作者 刘光彪 纪传波 段国学 《人民长江》 北大核心 2024年第1期236-241,共6页
大坝安全监测数据原始序列中常存在异常测值,极大影响了大坝安全监测资料分析的可靠性和准确性。为此,在分析异常值特性及传统异常检测方法优缺点的基础上,分别从局部与整体角度研究监测数据异常检测方法。首先针对多重局部异常系数法... 大坝安全监测数据原始序列中常存在异常测值,极大影响了大坝安全监测资料分析的可靠性和准确性。为此,在分析异常值特性及传统异常检测方法优缺点的基础上,分别从局部与整体角度研究监测数据异常检测方法。首先针对多重局部异常系数法要求数据序列较长且数据等时间间距等缺陷,提出了局部变化异常系数法(LV)及局部方法与整体方法协同判别策略;进一步引入密度聚类算法(DBSCAN),提出了兼顾数据整体与局部特性的LV-DBSCAN异常检测方法。以某混凝土重力坝两垂线测点顺流向位移监测数据为实例,对比分析了不同方法在不同类型数据集上的检测精度。研究结果表明,所提LV-DBSCAN方法适用性更广,准确率更高,误判率更低。 展开更多
关键词 大坝安全监测 异常值 局部变化异常系数法(LV) 密度聚类算法(DBScan) 置信度
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Spatiotemporal Variability and Environmental Controls of Temperature Sensitivity of Ecosystem Respiration across the Tibetan Plateau
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作者 Danrui SHENG Xianhong MENG +8 位作者 Shaoying WANG Zhaoguo LI Lunyu SHANG Hao CHEN Lin ZHAO Mingshan DENG Hanlin NIU Pengfei XU Xiaohu WEN 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第9期1821-1842,共22页
Warming-induced carbon loss via ecosystem respiration(R_(e))is probably intensifying in the alpine grassland ecosystem of the Tibetan Plateau owing to more accelerated warming and the higher temperature sensitivity of... Warming-induced carbon loss via ecosystem respiration(R_(e))is probably intensifying in the alpine grassland ecosystem of the Tibetan Plateau owing to more accelerated warming and the higher temperature sensitivity of R_(e)(Q_(10)).However,little is known about the patterns and controlling factors of Q_(10)on the plateau,impeding the comprehension of the intensity of terrestrial carbon-climate feedbacks for these sensitive and vulnerable ecosystems.Here,we synthesized and analyzed multiyear observations from 14 sites to systematically compare the spatiotemporal variations of Q_(10)values in diverse climate zones and ecosystems,and further explore the relationships between Q_(10)and environmental factors.Moreover,structural equation modeling was utilized to identify the direct and indirect factors predicting Q_(10)values during the annual,growing,and non-growing seasons.The results indicated that the estimated Q_(10)values were strongly dependent on temperature,generally,with the average Q_(10)during different time periods increasing with air temperature and soil temperature at different measurement depths(5 cm,10 cm,20 cm).The Q_(10)values differentiated among ecosystems and climatic zones,with warming-induced Q_(10)declines being stronger in colder regions than elsewhere based on spatial patterns.NDVI was the most cardinal factor in predicting annual Q_(10)values,significantly and positively correlated with Q_(10).Soil temperature(Ts)was identified as the other powerful predictor for Q_(10),and the negative Q_(10)-Ts relationship demonstrates a larger terrestrial carbon loss potentiality in colder than in warmer regions in response to global warming.Note that the interpretations of the effect of soil moisture on Q_(10)were complicated,reflected in a significant positive relationship between Q_(10)and soil moisture during the growing season and a strong quadratic correlation between the two during the annual and non-growing season.These findings are conducive to improving our understanding of alpine grassland ecosystem carbon-climate feedbacks under warming climates. 展开更多
关键词 carbon cycle eddy covariance measurements ecosystem respiration Q_(10)value Tibetan Plateau climate change
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Spatiotemporal Evolution of Ecosystem Service Value in Caohai National Nature Reserve
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作者 Denghong HUANG Zhenzhen ZHANG Jintong REN 《Meteorological and Environmental Research》 2024年第2期14-21,共8页
Wetland ecosystems are important regulators of global climate change.Studying the spatiotemporal changes and driving mechanisms of their ecosystem service values(ESV)is beneficial for the sustainable development of we... Wetland ecosystems are important regulators of global climate change.Studying the spatiotemporal changes and driving mechanisms of their ecosystem service values(ESV)is beneficial for the sustainable development of wetlands.This paper uses the equivalent factor method,based on land use changes,to reveal the spatiotemporal evolution of the ecosystem service value in the Caohai National Nature Reserve(CNNR).The results show the following:①from 2000 to 2020,there was a significant decrease in the core zone s arable land area,with an increase in forest and water areas.Construction land mainly increased in the experimental area,and the grassland area showed a fluctuating change of first increasing and then decreasing;②in 2000,2010,and 2020,the ecosystem service value of the study area was 302 million,296 million,and 325 million yuan,respectively,showing a trend of fluctuating growth,with the value of wetland ecosystems playing a dominant role;③regulatory services are the main contributors to the ecosystem service value in the study area,with a contribution rate of 60%.Hydrological regulation is the ecosystem function with the highest value in wetland ecosystem services,contributing more than 35%to the ESV in all three periods;④in terms of spatial distribution,the core zone s ecosystem service value is dominant.Looking at the total ecosystem service value of the region,the core zone>the experimental area>the buffer zone.In terms of ESV per unit area,the core zone(89000 yuan/hm^(2))is significantly higher than the buffer zone(39100 yuan/hm^(2))and the experimental area(15800 yuan/hm^(2)).The study can provide a basis for research and spatial management of ecosystem services in wetland ecosystems and nature reserves. 展开更多
关键词 Ecosystem service value(ESV) Equivalent factor method Land use change Wetland ecosystem CNNR
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The Impact of Carbon Emissions on Asset Values and Operating Cash Flows: Evidence From Australian Listed Companies
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作者 Li Yongqing Ian Eddie Liu Jinghui 《Journal of Modern Accounting and Auditing》 2013年第1期94-111,共18页
In November 2011, the Australian government approved the legislation (Clean Energy Act 2011) to introduce a reduction plan of carbon emissions in Australia. This plan will be implemented from July 2012. This is one ... In November 2011, the Australian government approved the legislation (Clean Energy Act 2011) to introduce a reduction plan of carbon emissions in Australia. This plan will be implemented from July 2012. This is one of the first accounting studies to investigate the potential impacts of this plan on long-lived asset values and operating cash flows for Australian listed companies. A sample of Australian Securities Exchange (ASX) 200 indexed companies from 2'006 to 2010 is used. Hypotheses are tested based on Heckman's (1979) two-stage approach. Three regression models are developed to examine the association between carbon emissions and asset values/operating cash flows. This study finds that asset values and operating cash flows will be adversely affected, if the reduction plan is implemented. Specifically, this study finds that the book value of long-lived assets will decrease, if listed companies are considered to be emissions-liable. The book value of long-lived assets is further found to be negatively associated with listed companies' carbon emission levels. This study also demonstrates that operating cash flows of emissions-liable companies will be adversely affected. However, this study does not find a relationship between operating cash flows and companies' emission levels. The empirical findings from Australian listed companies provide the evidence that the reduction plan of carbon emissions will adversely affect corporate entities' asset values and operating cash flows. The results further indicate that the magnitude of the impact will be proportional to the companies' emission levels. The implications of these empirical findings for listed companies, for the accounting profession, and for carbon emission regulators are also discussed. 展开更多
关键词 carbon emissions reduction asset values operating cash flows AUSTRALIA
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Continuing Value Calculation with Discounted Cash Flows Method: An Application Example for Tekart Tourism Establishment Whose Shares Are Dealt in Istanbul Stock Exchange
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作者 Eda Rukiye Donbak Ismail Ukav 《Journal of Tourism and Hospitality Management》 2016年第3期139-145,共7页
Valuation is stated as monetary value belonging to firm assets (Verginis & Taylor, 2004). According to M. L. Rock, R. H. Rock, and Sikora (1994), valuation is the answer of the following questions: What is the m... Valuation is stated as monetary value belonging to firm assets (Verginis & Taylor, 2004). According to M. L. Rock, R. H. Rock, and Sikora (1994), valuation is the answer of the following questions: What is the maximum price that will be paid for the firm? What are the risk areas? What are the results of cash flows, profitability, and balance-sheet? Chambers (2005, p. 5), on the other hand, estimated a probable price that will be paid for the goods and service at a specific time. For the calculation of continuing value (CV), Verginis and Taylor (2004) used discounted cash flows (DCF) method and Onal, Karadeniz, and Kandlr (2005) used economic profit method. Klrh (2005) suggested Continuous and Constant Growing Model (Gordon Model), Value Driver Model, and Economic Profit Model. In this study, DCF which is suggested by Onal et al. (2005) and Verginis and Taylor (2004) is used for the aim of determining CV of the firm at issue. In this study, analyses are made by using the financial statement data of a tourism business whose shares are dealt in Istanbul Stock Exchange. In consequence of the calculations, CV of the examined firm is found to be 7,485,402 TL and firm value is found to be 15,195,366 TL. 展开更多
关键词 firm evaluation continuing value (CV) discounted cash flows (DCF) discount rates
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Early Detection of Temporal Lobe Epilepsy: Identification of Novel Candidate Genes and Potential Biomarkers Using Integrative Genomics Analysis
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作者 Vishruth Nagam 《Open Journal of Genetics》 2020年第4期65-81,共17页
Currently afflicting more than 50 million people worldwide, epilepsy is the spectrum disorder characterizing seizures that occur without other plausible medical explanations. Temporal lobe epilepsy (TLE) is one of the... Currently afflicting more than 50 million people worldwide, epilepsy is the spectrum disorder characterizing seizures that occur without other plausible medical explanations. Temporal lobe epilepsy (TLE) is one of the most common forms of epilepsy. Current clinical methods;including MRI scans, EEG tests, and doctor visits;can take upwards of several months to confirm a TLE diagnosis;during this time, patients may experience additional seizures and are at an increased risk for other psychiatric disorders. The purpose of this study is to identify candidate genetic biomarkers to facilitate the earlier detection and diagnosis of TLE through gene-based testing (e.g., genomic heatmap analysis or genetic and/or microarray testing). It was hypothesized that potential biomarkers could be identified by analyzing genes that are normally significantly overexpressed in the temporal lobe relative to the gray matter. Statistical and functional analysis was performed on significantly overexpressed genes (≥3.000 fold change) in the gene expression profiles of four donors without epilepsy. The experimental-evidence-based STRING protein interactions analysis showed associations between genes found in DAVID keyword search and other genes facilitating network interconnectivity. After evaluation of the genes’ STRING enriched functions, changes in the expression of the genes <em>CAMK2A</em>, <em>NPY</em>, <em>DLG4</em>, <em>MEF2C</em>, and<em> MAPK7</em> were concluded to be potential biomarkers for TLE, confirming the original hypothesis. Specifically, the identification of <em>MEF2C</em> and <em>MAPK7</em> for this purpose is relatively novel in the fields of bioinformatics and neurogenetics. Future work includes investigating the utility of the candidate genes in real-world gene-based diagnostic methods. 展开更多
关键词 Temporal Lobe Epilepsy (TLE) Gene Expression Fold Change values Gene Ontology candidate Genes Keyword Search Four Individual Donors STRING Enriched Functions Protein Genes Highest Fold
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Small ruminant value chain in Al-Ruwaished District,Jordan
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作者 Rula AWAD Hosam TITI +2 位作者 Aziza MOHAMED-BRAHMI Mohamed JAOUAD Aziza GASMI-BOUBAKER 《Regional Sustainability》 2023年第4期416-424,共9页
This study aims to assess the small ruminant value chain in Al-Ruwaished District,Jordan,to identify the potential intervention areas that could improve the production efficiency and guarantee the sustainability of th... This study aims to assess the small ruminant value chain in Al-Ruwaished District,Jordan,to identify the potential intervention areas that could improve the production efficiency and guarantee the sustainability of the small ruminant sector in this area.Sheep breeding is the source of livelihood for most of the people in Al-Ruwaished District,which is characterized by the large number of sheep and goats.We surveyed 5.0% of the small ruminant holders in the study area and conducted individual interviews and surveys with the potential actors in the value chain to undertake a small ruminant value chain analysis.From the survey,we found that the small ruminant value chain consists of five core functions,namely,input supply,production management,marketing,processing,and consumption.Despite the stable impression given by the large number of holdings in the small ruminant sector,the surveyed results show a clear fragility in the value chain of small ruminants in this area.The small ruminant production system is negatively impacted by climate change,especially continuous drought.In addition,the high prices of feed that the farmer cannot afford with clear and real absence of the governmental and non-governmental support activities also impact the development of the value chain.The results of strengths,weaknesses,opportunities,and threats(SWOT)analysis reveal that the major constraints faced by this value chain could be divided into external and internal threats.Specifically,the most prominent external threats are the nature of the desert land and continuous drought,while the major internal threats are the absence of appropriate infrastructure,shortage of inputs,and weakness in the production management and marketing.We proposed solutions to these challenges to ensure the sustainability and effectiveness of the sector,such as the formulation of emergency response plans to severe weather,qualifying farmers’skills,and establishment of agricultural cooperative societies. 展开更多
关键词 value chain analysis Small ruminants Strengths weaknesses opportunities and threats(SWOT)analysis Climate change Livestock production management JORDAN
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Analysis of the USD/JPY and EUR/JPY Exchange Rates Using Multifractal Analysis and Extreme Value Theory
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作者 Fumio Maruyama 《Journal of Applied Mathematics and Physics》 2023年第10期2816-2827,共12页
We performed a multifractal analysis using wavelet transform to detect the changes in the fractality of the USD/JPY and EUR/JPY exchange rates, and predicted their extreme values using extreme value theory. After the ... We performed a multifractal analysis using wavelet transform to detect the changes in the fractality of the USD/JPY and EUR/JPY exchange rates, and predicted their extreme values using extreme value theory. After the 1997 Asian financial crisis, the USD/JPY and EUR/JPY became multifractal, then the USD/JPY became monofractal and stable, and yen depreciation was observed. However, the EUR/JPY became multifractal and unstable, and a strong yen depreciation was observed. The coherence between the USD/JPY and EUR/JPY was strong between 1995 and 2000. After the 2007-2008 financial crisis, the USD/JPY became monofractal and stable, and yen appreciation was observed. However, the EUR/JPY became multifractal and unstable, and strong yen appreciation was observed. Various diagnostic plots for assessing the accuracy of the GP model fitted to USD/JPY and EUR/JPY are shown, and all the diagnostic plots support the fitted GP model. The shape parameters of USD/JPY and EUR/JPY were close to zero, therefore the USD/JPY and EUR/JPY did not have finite upper limits. We predicted the maximum return level for the return periods of 10, 20, 50, 100, 350, and 500 years and their respective 95% confidence intervals (CI). As a result, the 10-year and 100-year return levels for USD/JPY were estimated to be 149.6 and 164.8, with 95% CI [143.2, 156.0] and [149.4, 180.1], respectively. 展开更多
关键词 WAVELET MULTIFRACTAL Extreme value Theory GP USD/JPY and EUR/JPY Ex-change Rates
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中国员工工作价值观的代际变迁 被引量:1
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作者 唐宁玉 甄丹蕾 关健 《心理学报》 CSCD 北大核心 2024年第7期876-894,I0001-I0003,共22页
随着时代发展,我国工作场所中的员工队伍构成呈现出多样化趋势。多代际并存,使得理解不同代际员工的工作价值观变得迫切而重要。本文基于Inglehart的现代化演进理论,通过采用不同研究设计、不同测量工具、不同分析方法和不同研究视角的... 随着时代发展,我国工作场所中的员工队伍构成呈现出多样化趋势。多代际并存,使得理解不同代际员工的工作价值观变得迫切而重要。本文基于Inglehart的现代化演进理论,通过采用不同研究设计、不同测量工具、不同分析方法和不同研究视角的三个研究,对不同代际(改革前一代、改革一代和后改革一代)员工工作价值观的变迁展开了系统而深入的分析。研究结果显示,我国不同代际员工的工作价值观既存在差异,又存在相似之处,后改革一代的工作价值观较之其他两代差异最为明显。具体而言,相比于改革前一代与改革一代,后改革一代的物质主义工作价值观最低,后物质主义工作价值观最高;后改革一代相比于前两个代际对开放工作价值观的重视程度最高,但三代员工在自我超越工作价值观上没有显著差异。研究还发现,不同代际员工对物质主义工作价值观的重视程度仍然高于后物质主义。本研究丰富了工作价值观代际差异以及新生代员工研究的知识体系,研究结果也可以为处在大变局中的企业管理实践提供借鉴和参考。 展开更多
关键词 工作价值观 代际差异 物质主义 后物质主义 开放-保守 自我增强-自我超越 APC分析方法
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多适应症药物医保支付的理论反思与实践走向——基于制度变迁视角
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作者 伍琳 廖诗语 +2 位作者 陈嘉怡 夏静琪 陈永法 《卫生经济研究》 北大核心 2024年第6期10-15,共6页
欧洲国家经验表明,实施多适应症药物支付(MIP)需要有三个方面的支撑条件。由于政策创新空间受限,且资源基础薄弱,当前我国实施MIP的难度较大。但随着社会经济形势变化,实施MIP的需求和条件基础也会不断变化,建议从公共价值创造、制度风... 欧洲国家经验表明,实施多适应症药物支付(MIP)需要有三个方面的支撑条件。由于政策创新空间受限,且资源基础薄弱,当前我国实施MIP的难度较大。但随着社会经济形势变化,实施MIP的需求和条件基础也会不断变化,建议从公共价值创造、制度风险分担、实践效果追踪三个层面,推动我国多适应症药物支付制度变革。 展开更多
关键词 多适应症药物 制度变迁 价值 真实世界数据
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四川通济堰的历史变迁、文化遗产价值与活化利用展望
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作者 刘礼堂 刘振 李怡博 《农业考古》 北大核心 2024年第4期131-139,共9页
本文通过系统梳理四川通济堰的历史变迁,力图发掘该工程蕴涵的文化遗产价值,并在此基础上提出了保护传承及活化利用展望。通济堰初修于西汉中后期,在唐宋时期尤其是南宋时期进入治理高峰,清代以降再度兴盛。在两千年的发展过程中,通济... 本文通过系统梳理四川通济堰的历史变迁,力图发掘该工程蕴涵的文化遗产价值,并在此基础上提出了保护传承及活化利用展望。通济堰初修于西汉中后期,在唐宋时期尤其是南宋时期进入治理高峰,清代以降再度兴盛。在两千年的发展过程中,通济堰工程成为区域史的一个重要组成部分,围绕该工程诞生了一批有影响力的文学作品,同时,它所蕴涵的先进技术价值也是独树一帜。这一工程彰显了中国古代灌溉工程高超的治水智慧,为可持续灌溉发展提供了历史经验和启示。 展开更多
关键词 通济堰 变迁史 文化遗产价值 活化利用
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华南晚籼杂交稻叶片SPAD值及其一般配合力和遗传效应的动态变化
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作者 廖亦龙 柳武革 +7 位作者 王丰 刘迪林 孔乐 李金华 霍兴 付崇允 朱满山 曾学勤 《中国农学通报》 2024年第3期1-7,共7页
本研究旨在揭示华南晚籼杂交稻叶片SPAD值一般配合力及遗传参数的动态变化规律,为华南杂交水稻的高产高效新品种培育提供相关的科学依据。以华南地区生产上广泛应用的3个籼稻不育系和6个籼稻恢复系配置了18个不完全双列杂交组合,分析不... 本研究旨在揭示华南晚籼杂交稻叶片SPAD值一般配合力及遗传参数的动态变化规律,为华南杂交水稻的高产高效新品种培育提供相关的科学依据。以华南地区生产上广泛应用的3个籼稻不育系和6个籼稻恢复系配置了18个不完全双列杂交组合,分析不同发育阶段叶片SPAD值及其一般配合力及遗传效应的动态变化规律。结果表明:杂种及其亲本叶片SPAD值移栽后呈逐渐下降趋势,于幼穗分化期(栽后43或50 d)达到最低点,始穗期(60 DAT)后快速下降。不同组合以及同一组合在不同发育时期叶片SPAD值存在较大差异。灌浆结实期至蜡熟期,‘荣丰A’、‘五丰A’、‘华占’和‘广恢308’及其相应组合叶片SPAD值下降较快,而‘明恢63’和‘桂99’及其相应杂交组合依然保持相对较高的SPAD值,并与亲本SPAD值一般配合力的动态变化相一致。除分蘖始期叶片SPAD值以特殊配合力为主外,达70.76%,其余发育阶段叶片SPAD值均以一般配合力起主导作用。杂种叶片SPAD值在生殖生长阶段的遗传力(21.90%~63.89%),显著高于其营养生长阶段的遗传力(8.02%~14.79%);其遗传效应以加性效应为主,同时存在显性或/和上位性效应,始穗期至抽穗扬花期的显性或/和上位性效应增大,达18.37%和22.02%。发育前期和中期,叶片SPAD值受环境条件影响较小,后期则较大地受到环境条件影响。 展开更多
关键词 杂交稻 SPAD值 一般配合力 遗传效应 动态变化
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经济政策不确定性与企业现金持有价值——有调节的中介效应
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作者 吴以 杨夏妮 《技术经济与管理研究》 北大核心 2024年第3期86-92,共7页
随着宏观环境波动,企业受经济政策不确定性影响较大,其对现金持有价值的影响以及渠道机制值得关注。基于沪深A股2013—2021年上市公司面板经验证据,对经济政策不确定性与企业现金持有价值的关系进行探讨,分析发现:经济政策不确定性对企... 随着宏观环境波动,企业受经济政策不确定性影响较大,其对现金持有价值的影响以及渠道机制值得关注。基于沪深A股2013—2021年上市公司面板经验证据,对经济政策不确定性与企业现金持有价值的关系进行探讨,分析发现:经济政策不确定性对企业现金持有价值具有积极效应,经济政策不确定性通过加剧融资约束程度进而提高企业现金持有价值,在投资者保护度较低、非国有企业以及企业成长性较高时该正向促进作用更强,客户集中度在“经济政策不确定性—融资约束—企业现金持有价值”的整个路径和前半路径具有显著调节作用。由此,提出政府应考虑企业的风险承受能力、引导企业建立风险应对机制、促进资本市场改革、完善资金信用机制等政策建议。 展开更多
关键词 企业现金持有价值 融资约束 经济政策不确定性 企业发展
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基于价值观的气候传播:中国Z世代价值观念与气候叙事探究
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作者 曾繁旭 张智鹏 《上海交通大学学报(哲学社会科学版)》 北大核心 2024年第7期27-44,共18页
随着“双碳”目标的提出,中国正式迈入“双碳”时代,Z世代因其特殊的世代坐标,是决定未来“双碳”目标顺利实现与否的关键群体。文章以中国Z世代公众为研究对象,提出以价值观念作为气候传播中叙事设计的主要依据。研究中招募54名中国Z... 随着“双碳”目标的提出,中国正式迈入“双碳”时代,Z世代因其特殊的世代坐标,是决定未来“双碳”目标顺利实现与否的关键群体。文章以中国Z世代公众为研究对象,提出以价值观念作为气候传播中叙事设计的主要依据。研究中招募54名中国Z世代志愿者,共计开展12次焦点小组访谈,探讨他们的价值观念和气候态度,随后邀请他们进行叙事语料测试,语料的不同段落和表述暗含了对应的价值观念假设。通过对焦点小组和语料测试的质性材料分析,发现Z世代群体普遍体现出自我提升和“躺平”期待的并存、强烈的国族认同感以及平等主义倾向,同时既自我关注又有较低的自我效能感。文章尝试建立起价值取向与气候认知和态度之间的可靠关联,并总结了Z世代价值偏向对气候叙事实践的启示。 展开更多
关键词 价值观 Z世代 气候传播 气候认知与态度 气候叙事
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市场化进程、融资约束与现金持有价值
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作者 吴以 荆倩倩 杨夏妮 《科技与经济》 2024年第1期71-75,共5页
选取我国沪深A股上市企业2013—2021年财务数据为样本,运用固定效应模型检验市场化进程对企业现金持有价值的影响及其渠道机制。研究得出:市场化进程对现金持有价值具有显著负向效应,并且融资约束起中介效应;异质性分析中发现在投资者... 选取我国沪深A股上市企业2013—2021年财务数据为样本,运用固定效应模型检验市场化进程对企业现金持有价值的影响及其渠道机制。研究得出:市场化进程对现金持有价值具有显著负向效应,并且融资约束起中介效应;异质性分析中发现在投资者保护度较低、信息不对称程度较高以及企业成长性较高时该效应更明显。进一步研究得出,现金持有水平还有利于缓解企业的经营风险,促进经营业绩。渠道机制表明持有高额的现金能够发挥预防性功能,在市场化进程较低时可以提高现金持有价值;企业要制定较有弹性的现金持有政策以应对不断变化的外部市场环境;对于持有现金政策的制定不可忽略融资约束这一重要中介变量。 展开更多
关键词 现金持有价值 市场化进程 融资约束 中介效应
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基于LUCC的生态系统服务价值时空演变——以祁连山区域为例
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作者 马鑫 李广 李杰 《草业科学》 CAS CSCD 北大核心 2024年第6期1492-1505,共14页
分析祁连山区域生态系统服务价值的时空变化特征,可为该区土地高效开发利用、生态恢复与保护机制的构建提供数据支撑。基于1980年、1990年、2000年、2010年和2020年的土地利用数据,运用改进的当量因子定量评估祁连山区域不同历史时期的... 分析祁连山区域生态系统服务价值的时空变化特征,可为该区土地高效开发利用、生态恢复与保护机制的构建提供数据支撑。基于1980年、1990年、2000年、2010年和2020年的土地利用数据,运用改进的当量因子定量评估祁连山区域不同历史时期的生态系统服务价值,结合空间自相关及GIS空间统计方法,探究研究区不同乡镇的地均生态系统服务价值时空变化特征。结果表明:1)1980-2020年,研究区主要土地类型为未利用地、草地、林地、耕地,总覆盖率在93%以上。其中林地和未利用地面积减少,建设用地动态度变化最大。2)1980-2020年,祁连山区域生态系统服务总价值增加了170.8285×10^(8)元,其中草地、林地和水域的生态服务价值占78%,水文调节和气候调节的生态服务价值占60.14%。3)地均生态系统服务价值的空间正相关性较明显,空间集聚程度较高。高值聚集区有由增加向减少转变的趋势,低值聚集区逐年增加。4)1980-2010年,祁连山区域南部生态系统服务价值高于北部,北部生态系统服务价值在2010年后有增加趋势,但研究区南北间生态系统服务价值还未达到均衡和稳定。 展开更多
关键词 土地利用 生态系统服务价值 当量因子 动态度 时空变化 空间自相关 聚集区
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我国职业教育产教融合政策变迁历程与动力机制——间断-均衡理论视角
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作者 张茜 许祥云 黄志雄 《高校教育管理》 北大核心 2024年第5期74-86,共13页
产教融合是职业教育实现高质量发展的关键。以间断-均衡理论为基础,借助政策范式理论,本研究构建职业教育产教融合政策变迁分析框架,运用内容分析法对新中国成立以来职业教育产教融合政策变迁逻辑进行客观梳理与系统剖析。研究验证并拓... 产教融合是职业教育实现高质量发展的关键。以间断-均衡理论为基础,借助政策范式理论,本研究构建职业教育产教融合政策变迁分析框架,运用内容分析法对新中国成立以来职业教育产教融合政策变迁逻辑进行客观梳理与系统剖析。研究验证并拓展了间断-均衡理论的适用性,发现职业教育产教融合政策呈现渐进性均衡和突发性间断相结合的变迁样态,具有非线性发展特征。制度环境和价值理念是推动政策变迁的主要动力,焦点事件通过影响决策者注意力为政策变迁开启“机会之窗”。强化顶层设计与政策供给、建立开放包容的政策场域、完善政策试点与保障机制是推动我国职业教育产教融合高质量发展的应然路径。 展开更多
关键词 职业教育 产教融合 政策变迁 间断-均衡理论 制度环境 价值理念 焦点事件
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人工智能时代价值理论的创新逻辑与制度变革
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作者 李松龄 《经济研究参考》 2024年第8期5-16,共12页
超额剩余价值转化的利润积累为资本,有利于促进人工智能技术可持续开发和应用于生产。资本购买人工智能技术商品并应用于生产,形成的社会价值高于个别价值的超额剩余价值,不由个别劳动生产。通过出售个别商品使用价值,资本有偿占有超额... 超额剩余价值转化的利润积累为资本,有利于促进人工智能技术可持续开发和应用于生产。资本购买人工智能技术商品并应用于生产,形成的社会价值高于个别价值的超额剩余价值,不由个别劳动生产。通过出售个别商品使用价值,资本有偿占有超额剩余价值不是对个别劳动的剥削。资本支付工资购买科技劳动力,用于开发和应用人工智能技术,超额剩余价值的形成有科技劳动的贡献。构建生产资料资本化为资本所有者股份和劳动力资本化为劳动者股份相结合的新型股份制,能够保障科技劳动占有超额剩余价值。非物质生产的第三产业的劳动成为生产劳动,能够生产商品和剩余价值,增殖资本,有利于第三产业的发展和壮大,有利于扩大社会劳动和社会价值,形成超额剩余价值。 展开更多
关键词 人工智能时代 价值理论 创新逻辑 制度变革
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论美丽中国建设背景下我国环境经济学学科的发展方向
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作者 庞军 梁宇超 秦海翔 《中国环境科学》 EI CAS CSCD 北大核心 2024年第7期4084-4090,共7页
环境经济学是一门研究经济发展与环境保护之间相互关系的经济学分支学科.在全面建设美丽中国的时代背景下,环境经济学学科的发展面临新的机遇与挑战.本文分析了在美丽中国建设背景下中国环境经济学科的主要发展方向.首先,简述了环境经... 环境经济学是一门研究经济发展与环境保护之间相互关系的经济学分支学科.在全面建设美丽中国的时代背景下,环境经济学学科的发展面临新的机遇与挑战.本文分析了在美丽中国建设背景下中国环境经济学科的主要发展方向.首先,简述了环境经济学学科的诞生背景与发展的历史脉络,梳理了中国环境经济学学科的发展进程;其次,总结了环境经济学学科主要的研究领域,归纳了环境经济政策设计与评估、费用-效益分析、环境价值评估与气候变化经济学四个领域的核心研究内容;然后,阐述了环境经济学学科从哪些角度可以回应美丽中国建设中的重要任务;最后,论述了中国环境经济学学科可以从环境政策与制度、绿色金融、污染与健康、生态产品价值评估与实现、气候应对与国际合作等多个角度做出创新,助力美丽中国建设. 展开更多
关键词 美丽中国建设 环境经济学 环境经济政策 费用-效益分析 环境价值评估 气候变化经济学
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自由现金流量折现法下海尔智家企业价值评估
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作者 刘晓慧 《现代工业经济和信息化》 2024年第5期231-234,共4页
选取家电企业中更为注重智能化技术投入的海尔智家为案例,采用自由现金流量折现法对发展智能技术后海尔智家企业的价值进行评估,旨在对海尔智家进行客观评价。通过分析研究得出了海尔智家在未来5年内持续稳步增长的结论,未来的发展较为... 选取家电企业中更为注重智能化技术投入的海尔智家为案例,采用自由现金流量折现法对发展智能技术后海尔智家企业的价值进行评估,旨在对海尔智家进行客观评价。通过分析研究得出了海尔智家在未来5年内持续稳步增长的结论,未来的发展较为可观。 展开更多
关键词 智能化 海尔智家 自由现金流量折现法 企业价值
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