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1.
基于CGE模型的林业碳税在森林采伐管理中的应用   总被引:1,自引:0,他引:1  
【目的】为了协调采伐限额管理及采伐许可证等现有森林采伐管理制度与林权市场化改革的矛盾,通过控制碳排放的碳税制度来改变森林采伐的行政管理制度。【方法】在现有商品林的采伐管理制度中引入“林业碳税”,并借助一般均衡(CGE)模型对在森林采伐环节中针对商品林采伐所涉及的碳排放量征收的林业碳税进行定量分析。测定了森林采伐环节中的碳排放量及林业碳税税率范围,并模拟林业碳税在5、10、20、30、40元/m35种税率情景下对林业投资、林业支出、碳排放量、各部门收益的影响。【结果】为了描述林业碳税对木材采伐量的可控性,构造的林业碳税CGE模型包括生产模块和经济主体模块两部分。生产模块由林产品流向、森林资源培育费用及市场总供给3类方程构成,经济主体模块则描述了各经济主体的收益和支出,以及相互间的转移支付,在设定的5种林业碳税税率中,20~30元/m3时,林业投资与支出、碳排放量及各部门收益等变化情况达到最佳。同时林业碳税应从征收目的、调节作用、税收归属及征税基本原则4个方面进行制度设计。【结论】林业碳税的征收能够平衡木材采伐量,获得的林业碳税收入应用于减少木材采伐行为的补偿,同时应该坚持激励和约束并重、税率设置循序渐进和动态调整、不同林区区别对待又合理借鉴的原则。  相似文献   

2.
在支持电压岛的片上网络体系结构中,考虑供应电压对数据重传的影响,提出了一种新的能耗模型,并提出了基于电压岛划分、IP核映射和路由算法设计的架构方法.该方法针对电压岛划分、IP核映射和路由算法设计等问题,不仅考虑了IP核的计算能耗,还考虑了IP核之间数据在重传下的数据通信能耗问题.实验结果表明,在考虑数据重传的情况下,该设计方法能有效地降低系统能耗.  相似文献   

3.
Deforestation in mid- to high latitudes is hypothesized to have the potential to cool the Earth's surface by altering biophysical processes. In climate models of continental-scale land clearing, the cooling is triggered by increases in surface albedo and is reinforced by a land albedo-sea ice feedback. This feedback is crucial in the model predictions; without it other biophysical processes may overwhelm the albedo effect to generate warming instead. Ongoing land-use activities, such as land management for climate mitigation, are occurring at local scales (hectares) presumably too small to generate the feedback, and it is not known whether the intrinsic biophysical mechanism on its own can change the surface temperature in a consistent manner. Nor has the effect of deforestation on climate been demonstrated over large areas from direct observations. Here we show that surface air temperature is lower in open land than in nearby forested land. The effect is 0.85 ± 0.44 K (mean ± one standard deviation) northwards of 45° N and 0.21 ± 0.53 K southwards. Below 35° N there is weak evidence that deforestation leads to warming. Results are based on comparisons of temperature at forested eddy covariance towers in the USA and Canada and, as a proxy for small areas of cleared land, nearby surface weather stations. Night-time temperature changes unrelated to changes in surface albedo are an important contributor to the overall cooling effect. The observed latitudinal dependence is consistent with theoretical expectation of changes in energy loss from convection and radiation across latitudes in both the daytime and night-time phase of the diurnal cycle, the latter of which remains uncertain in climate models.  相似文献   

4.
目的:建立CpG岛甲基化测定方法,方法:收集20例急性粒细胞性白血病(AML),18例多发性骨髓瘤(MM),14例骨髓异常增生综合征(MDS),15例慢性粒细胞性白血病(CML)及20 例正常对照组的外周血,分离单个核细胞,提取DNA,应用CpG岛思虑在化特异的方法(MSP-PCR),测定P15和P16基因甲基化情况,结果:P15和P16基因甲基化在各种白血病的表率率分别为AML 80%和70%,MM72.2%和66.7%,MDS 57.1%和50%,CML0%,结论:P15及P16基因甲基化在AML,MM及MDS中有较高表达,而在CML中不表达。  相似文献   

5.
结合科学技术与法律之间的关系,分析了如何从科学技术角度理解《海洋法公约》关于岛屿制度的规定。指出有效控制原则是国际法院解决岛屿争议的主要原则,而科学技术是实现对岛屿有效控制的重要手段。法律可以规范科学技术对岛屿问题产生的负面影响。  相似文献   

6.
盗伐、滥伐林木材积数量是对案件定性、对行为人处罚的重要依据。目前材积测算的方法较多,相关法律法规对测算方法没有统一规定,导致同一案件出现多个测算结果。笔者采用案例研究、调查访问、模拟现场调查等方法,根据涉案林木的状态,分别对几种常用的测算方法的精度进行了比较研究,提出应根据不同案情确定材积测算方法;同一案情有多种测算方法时,应优先选用精度较高的方法,使测算结果具有唯一性,并经司法机关认可取得合法性。这样对盗伐、滥伐林木案件进行定案时可减少争议的出现,缩短办案时间,提高办理毁林案件的质量。  相似文献   

7.
CpG island methylation plays important role in various biological processes. To investigate methylation landscape of all CpG islands on the human genome, we develop a model for predicting the CpG island methylation status. This model outperforms other existing methods. We apply the model on the whole human genome and predict the landscape of DNA methylation of all CpG islands. Based on the methylation profile, we find that about 31% of CpG islands are methylation-prone and CpG islands located in promoter regions are seldom methylated. There is no significant difference in the CpG island methylation level between R and G bands among the chromosomes. The occupancy of RNA polymerase II is significantly higher in methylation-resistant promoter CpG islands, indicating that genes with such promoter CpG islands tend to be more active.  相似文献   

8.
Demethylation of CpG islands in embryonic cells   总被引:16,自引:0,他引:16  
D Frank  I Keshet  M Shani  A Levine  A Razin  H Cedar 《Nature》1991,351(6323):239-241
DNA in differentiated somatic cells has a fixed pattern of methylation, which is faithfully copied after replication. By contrast, the methylation patterns of many tissue-specific and some housekeeping genes are altered during normal development. This modification of DNA methylation in the embryo has also been observed in transgenic mice and in transfection experiments. Here we report the fate in mice of an in vitro-methylated adenine phosphoribosyltransferase transgene. The entire 5' CpG island region became demethylated, whereas the 3' end of the gene remained modified and was even methylated de novo at additional sites. Transfection experiments in vitro show that the demethylation is rapid, is specific for embryonic cell-types and affects a variety of different CpG island sequences. This suggests that gene sequences can be recognized in the early embryo and imprinted with the correct methylation pattern through a combination of demethylation and de novo methylation.  相似文献   

9.
The distribution of sources and sinks of carbon among the world's ecosystems is uncertain. Some analyses show northern mid-latitude lands to be a large sink, whereas the tropics are a net source; other analyses show the tropics to be nearly neutral, whereas northern mid-latitudes are a small sink. Here we show that the annual flux of carbon from deforestation and abandonment of agricultural lands in the Brazilian Amazon was a source of about 0.2 Pg Cyr(-1) over the period 1989-1998 (1 Pg is 10(15) g). This estimate is based on annual rates of deforestation and spatially detailed estimates of deforestation, regrowing forests and biomass. Logging may add another 5-10% to this estimate, and fires may double the magnitude of the source in years following a drought. The annual source of carbon from land-use change and fire approximately offsets the sink calculated for natural ecosystems in the region. Thus this large area of tropical forest is nearly balanced with respect to carbon, but has an interannual variability of +/- 0.2 PgC yr(-1).  相似文献   

10.
采用不规则网格的有限体积海洋模型(FVCOM),建立了瓯江河口潮流数值模型,模型与实测数据在潮位、流速,流向上吻合,模型验证结果良好。以瓯江河口温州浅滩连岛工程为例,分析了无连岛工程,全围连岛工程,设1 000 m潮流通道连岛工程,只有北堤的连岛工程四种不同工况下的水动力特性,从水动力和围垦方面说明工程的合理性。  相似文献   

11.
利用Best Track资料、TRMM卫星资料和NCEP再分析资料中2001—2014年西北太平洋海域385个热带气旋(TC)的4967个观测记录, 将TC结构变化分成9类, 并分析 TC结构变化对垂直风切变和水汽场的响应。结果表明, 西北太平洋强度增大的TC主要伴随东风切变, 强度减小的TC主要伴随西风切变。在较强的垂直风切变(v > 5 m/s)作用下, TC的结构变化没有明显的水汽异常; 而在较弱的垂直风切变(v ≤ 5 m/s)作用下, “增强增大” (“缩小减弱”)的TC伴随着正(负)水汽异常。  相似文献   

12.
The fine structure of M/A islands in pipeline steel X70 has been studied by transmission electron microscope (TEM). It is shown that the M/A islands are about 1-2 μm in size and distribute at the grain boundary of irregular massive ferrite or acicular ferrite in the microstructure of the steel undergoing TMCP (thermo-mechanical controlled processing). The analysis of diffraction contrast shows that the M/A islands consist of retained austenite and some martensite lamellae different in size and orientation. The microtwinning and midrib exist in the lamella of lenticular martensite, which exhibit the typical character of high-carbon martensite. The influences of TMCP parameterson M/A islands have been studied carefully. With the increase of the cooling speed, the amount of M/A islands decrease slightly and the morphology of M/A islands changes to thin dispersive short bars from thick irregular long strips.  相似文献   

13.
浙江省海岛旅游可持续发展研究   总被引:1,自引:0,他引:1  
浙江省海岛区旅游资源丰富,是旅游发展最有潜力的区域,从海岛旅游资源特征与优势分析出发,重点探讨了海岛区旅游资源的可持续利用与旅游业的可持续发展问题。  相似文献   

14.
CpG-rich islands and the function of DNA methylation   总被引:332,自引:0,他引:332  
A P Bird 《Nature》1986,321(6067):209-213
It is likely that most vertebrate genes are associated with 'HTF islands'--DNA sequences in which CpG is abundant and non-methylated. Highly tissue-specific genes, though, usually lack islands. The contrast between islands and the remainder of the genome may identify sequences that are to be constantly available in the nucleus. DNA methylation appears to be involved in this function, rather than with activation of tissue specific genes.  相似文献   

15.
【目的】对常州市近30年热岛变化特征进行分析,并且分析城市热岛强度与植被、水体以及其他土地覆盖类型之间的关系。【方法】以整个常州市为研究对象,利用Artis&Camahan 的辐射校正温度反演法进行了地表温度反演,分析了常州市1988—2014年的城市热岛效应及空间变化。【结果】常州市在近30年来城市热岛范围,城区主要热岛区域与建成区保持一致,大量的人工下垫面、高密度建筑等扩张,造成高温区逐渐增多,热岛效应也越来越明显。【结论】常州市的热岛分布特征与常州市的土地利用类型有较好的一致性。低温区主要集中在植被和水体的区域,植被能够有效地起到降温的作用。  相似文献   

16.
风车草泡板型浮岛在污染河水中的脱氮试验   总被引:4,自引:0,他引:4  
介绍了泡板型浮岛在污染河水中的脱氮试验.实验表明浮岛植物的脱氮效能依次为:风车草>香根草>菖蒲.研究了去除负荷与覆盖率及进水负荷之间关系,结果表明以30%覆盖率为分界点,去除负荷与覆盖率之间的关系有明显的变化;去除负荷与进水负荷之间满足二次函数关系.最后得出了实验条件下的最适宜的覆盖率和进水负荷.  相似文献   

17.
利用完全耦合的气候模式进行敏感性试验, 定量研究副热带太平洋不同经度带的海表面温度异常(SSTA)对赤道太平洋的影响。研究发现, 赤道表层和温跃层海温对副热带太平洋(20°?30°N)西部、中部和东部SSTA的热力响应是相当的。 研究中强调大气?海洋耦合在副热带SSTA影响赤道温跃层过程中的决定性作用, 并提出一种间接的、较“海洋通道”机制更为快速的机制: 副热带SSTA引发局地大气的气旋性响应, 继而引起局地海洋内区的上升流和其面向赤道一侧海洋内区的下沉流, 该下沉流造成的局部温跃层暖异常向着赤道传播, 导致赤道温跃层增暖。  相似文献   

18.
Arid climatic and semi-aridclimatic conditions in Pakistan make the country’s forest deficient.This article aims to highlight the issues caused by deforestation of the country through systematicanalysis of the underlying issues.This is the first study depicting the realistic figures about the current situation of forests in the country with the contrary analysis based on the data provided by the national as well as international organizations.Empirical analysis is performed,based on the integration of the underlying causes of deforestation,primarily commercialization,growing agriculture,expanding urbanization,poverty,corruption,illegal logging,and other natural factors.Increasing population pressure and the other major causes of forest degradation are explored.Poorconservation management in most of the natural forests,as well as the high dependence of urban and rural households on wood for fuel,further impactthese issues.Moreover,grazing practices that disregard scientific limits,fires,storms,andinadequate financial investment,exacerbate these problems.Critically,a lack of stakeholder involvement in the policy making process contributes to the overall challenges faced in Pakistan’s forests.As a result oftheseissues,forests have been declining at an alarming rate in Pakistansince 2000.In 2005,the total forested area was 4.6 million hectares(Mha),around 5.77%of the overall land area of the country.By 2015,this had decreased to 4.265Mha.Concurrently,the annual rate of deforestation has increased from 1.63%in 2000 to 2.54%in 2015.Extensive deforestation has led to devastating effects,particularly floods and water erosion.This article suggests that,regardless of competing interests,stakeholders’involvement in policy making must increase if the issues of deforestation in Pakistan are to be arrested.  相似文献   

19.
2017年党的19大报告明确指出“要提高对污染排放的限制标准,强制披露环境信息”,意味着作为社会责任的重要组成部分,环境披露问题已经成为社会关注的焦点。在此背景下,研究企业环境信息披露的影响因素具有重要的现实意义。本文以采掘业中80家上市公司2010到2018年九年的有关数据为样本,从股权集中度视角实证检验了环境绩效和环境信息披露的关系,结果表明:(1)在重污染企业中,环境绩效对环境信息披露水平存在正向的引导作用;(2)股权集中度在环境绩效对环境信息披露的的影响中起到强化作用;(3)国有企业的股权集中度对环境绩效和环境信息披露的调节作用更显著。  相似文献   

20.
海南岛周边海域岛屿药用植物资源与开发利用   总被引:4,自引:0,他引:4  
通过对海南岛周边海域岛屿药用植物进行采集调查、鉴定统计,共计有478种。分别隶属于123科356属。并对药用植物资源的开发和利用提出建议,为研究和合理利用海南岛周边海域岛屿药用植物资源提供基础材料。  相似文献   

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