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关键词： Alpine grassland   C/N/P stoichiometry   Grassland degradation   Root biomass   Soil carbon stock  

摘要： Purpose Degradation of grassland creates diverse vegetation patch types with plant species with different palatabilities, potentially affecting ecosystem productivity and soil organic carbon (SOC) sequestration. This study investigated variations in SOC densities and carbon/nitrogen/phosphorus (C/N/P) ratios among vegetation patch types in a degraded alpine steppe on the Qinghai-Tibetan Plateau. Materials and methods We examined soil, shoot and root C, N and P densities, and C/N/P ratios in a growing season for five vegetation patch types dominated by palatable plant species Stipa purpurea, S. purpurea and Poa litwinowiana, and unpalatable plant species Leontopodium nanum, Artemisia nanschanica, and Oxytropis glacialis. Results and discussion Soil C and N as well as shoot and root densities varied among patch types, but not soil C/N. Patches dominated by unpalatable plant species had a lower SOC density, lower soil and plant N/P ratios, and greater plant nutrient densities than those dominated by palatable plant species. Vegetation patch type strongly influenced nutrient densities and ratios in soil-plant systems, and sampling only areas dominated by palatable plant species may overestimate the C sequestration rate at the ecosystem scale. Conclusions Even though patch-level plant biomass and nutrient density may increase with increasing degradation, the decrease in palatability and SOC storage at the ecosystem scale would impair grassland sustainability as alpine grassland degradation proceeds. The palatability of plants should thus be considered for improving regional SOC stock estimate in future research.

关键词： Business ethics   Computer ethics   Financial information   Cybercrime   Computer security   Stock value  

摘要： Purpose Cybercrime is a prevalent and serious threat to publicly traded companies. Defending company information systems from cybercrime is one of the most important aspects of technology management. Cybercrime often not only results in stolen assets and lost business but also damages a company's reputation, which in turn may affect the company's stock market value. This is a serious concern to company managers, financial analysts, investors and creditors. This paper aims to examine the impact of cybercrime on stock prices of a sample of publicly traded companies. Design/methodology/approach Financial data were gathered on companies that were reported in news stories as victims of cybercrime. The market price of the company's stock was recorded for several days before the news report and several days after. The percentage change in the stock price was compared to the change in the Dow Jones Industrial average to determine whether the stock price increased or decreased along with the rest of the market. Findings Stock prices were negatively affected in all time periods examined, significantly so in one period.

关键词： 价值投资策略   股票市场   有效性  

摘要： 近年来,随着我国整体社会水平的进步和提升,经济水平也得到了稳定的提升,在此种背景下,我国股票市场也得到了十分明显的进步。文章将以价值投资策略作为主要线索,根据不同时段内对高市盈率和低市盈率的股票收益率水平展开相应研究,从而对股票组合实际发展情况进行分析对比,希望这项工作的开展对于股票市场有效性的提升提供更大的帮助作用。

关键词： 林权价值   碳汇   收益净现值法  

摘要： 由于现有的林权评估方法只考虑了林木或林地的经济价值,而忽略了其天然的生态价值,在价值评估时缺乏完整性和多样性;森林的碳汇功能创造了新的二氧化碳排放空间,所以碳汇的经济价值一定程度上反应了林业的生态价值。因此,通过创新附碳汇收益的林权价值评估方法,即结合森林蓄积量转换法对收益净现值模型进行改进,既考虑林权的经济价值,又考虑其生态价值,以实现林业产业的外部效应内部化,促进生态经济的可持续发展。

关键词： 净现值   内含报酬率   图示法  

摘要： 净现值和内含报酬率是项目投资决策的两大财务评价指标,本文运用图示法直观形象的展现了两者的关系,有效解决了两者的互判性问题,创造了联通净现值与内含报酬率的新纽带。

关键词： 天然气   管道工程   经济评价   区间费用现值差额法  

摘要： 经过对比分析常用的天然气管道工程经济评价方法及特点,发现传统方法在整条管道建设及压气站建设方案和逐年下游市场量不确定的情况下很难做出经济判断。由此,根据费用现值法公式推导出了区间费用现值差额法的判断公式,其特点是以"理性人"假设为基础,适用于输量单调递增区间,通过相邻压气站建站方案递进比选确定最优方案,不考虑投资方案的收益,仅考虑投资、经营成本或残值的现值。区间费用现值差额法可以在已知低输量运行方案而高输量运行方案不明确的情况下,对新建管道压气站的提前建设经济有效性做出判断,对新建管道下游市场波动较大或动向不明时,做出合理正确的压气站建设方案判断。

关键词： 宏观金融   利率期限结构   仿射无套利模型   动态随机一般均衡  

摘要： 以利率为桥梁,金融和宏观经济的融合研究已成为趋势,表现在宏观经济一金融利率期限结构模型的不断拓展和深化。相关研究可分三个方面:首先,在标准的金融仿射无套利期限结构模型中加入宏观经济的因素,表明标准的金融期限结构的潜在构成因素也包括宏观经济基础。其次,将宏观经济动态随机一般均衡模型(DSGE)与债券定价结合起来,发掘其金融学意义。通过引入DSGE模型,可以对资产价格进行更好的解释。再次,发展一种实证上易处理的无套利期限结构模型,有利于期限结构模型向宏观金融领域的扩展,而能识别潜在收益率曲线因子的AFNS模型就具有这种性质,并表现出很好的实证预测效果,有助于阐明很多问题。展望未来,宏观经济一金融模型在关于债券供给和债券风险溢价之间的联系这一领域将取得更大的进展。

关键词： 历史成本   现值   会计计量  

摘要： 历史成本、现值是两种重要的会计计量的属性,这两种属性有着各自的优缺点,因而也就适合不同的会计计量情形。公允价值被广泛认可为新会计准则的主要亮点,现值是公允价值的难点与核心所在,历史成本则是传统的会计核算的一种重要属性,侧重于对会计信息可靠性的解决,对历史成本与现值进行了对比分析,并提出在会计计量工作中正确使用这两种计量属性的相关策略。

关键词： 主成分   有色金属股票   投资价值  

摘要： 股票价值分析是指通过对与股票价值相关的信息进行综合,对影响股票价格的因素进行专业的分析,进而对股票价值进行判断的行为过程,是金融市场参与者投资过程中一个重要环节。本文基于上市公司的一些基本财务指标,以有色金属行业为例,利用主成分分析对有色金属股票进行了综合评价,为投资者进行价值投资提供了理论依据。

关键词： 预付年金   普通年金   终值   现值   调整  

摘要： 预付年金终值、现值计算公式推导时,可以先把预付年金调整为普通年金,计算出该普通年金的终值或现值,然后分析该普通年金终值或现值与预付年金终值或现值的区别,再将该普通年金的终值或现值调整为预付年金的终值或现值。