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81.
气候变化与黄河中下游地区的早期稻作农业   总被引:1,自引:0,他引:1  
随着中国全新世大暖期的到来,黄河中下游地区迎来了温暖湿润的气候环境,这为农业生产提供了前所未有的优越条件。虽然黄河中下游地区是以旱作农业为主体的,但在粟作农业发展的同时,稻作农业也在孕育发生。从距今七八千年的裴李岗文化时期直到夏商时代,尽管其间气候状况发生过冷暖波动,稻作的发展也存在有起伏变化,但在整个全新世大暖期,稻作农业基本上都在逶迤发展着。实际上在全新世大暖期存在着一个粟稻混作区,其范围随着气候变化虽在不断波动,但大体位置在黄淮之间。这与黄河中下游地区所处的南北生态过渡带的地理环境密不可分,也是南北文化交流的重要体现。从裴李岗文化时期到夏商时代的早期稻作农业,也经历了一个发生、发展的演变过程,它对黄河流域的古代农业及社会发展产生了深远的影响,也充分显示了气候变化对农业和社会发展的重要影响及作用。  相似文献   
82.
When land parcel boundaries are surveyed for purposes of registration in most southern African countries, the cadastral survey records and diagrams prepared have to be examined and approved by the Surveyor General first before they can be registered in the Deeds Registries. For such records to be approved, their quality must conform to requirements stipulated in relevant acts and regulations. Where regulatory requirements are not met, the records are rejected and returned for corrections and resubmission. From a cross-organizational context, poor quality documents lodged upstream have the effect of congesting examination processes downstream as records are rejected and returned backwards due to quality failure. The paper proposes a quality performance measurement model to analyze quality performance in land administration work processes. The developed model is tested on 2 survey examination and approval sites and 3 deeds registration sites in Namibia, Zimbabwe and South Africa. Based on below expected quality results obtained at one of the sites, a root cause analysis was conducted to establish recurring and underlying causal factors upon which quality improvement strategies can be built on.  相似文献   
83.
目前,挖掘机正被广泛应用于基本建设的各个领域,为了适应各种不同的复杂作业需求,施工中需要频繁更换不同工作装置,挖掘机快换装置用于各类工作装置机具的快速更换,可提高工作效率实现一机多能。  相似文献   
84.
在地勘单位企业化进程中,财务部门对单位经济活动、资金运行具有极其重要的监督职能,把好财务这道闸门,对于防止国有资产流失具有举足轻重的作用。目前地勘单位财务部门财务监督尚存在对预算编制不够重视,费用支出管理制度不够健全,会计信息模糊,财务人员索质不高等问题。应从依法理财,健全内部控制制度,完善内部监督,加强社会监督,加大违法违规的处罚力度,提高会计人员素质等方面入手加强财务监督。  相似文献   
85.
This study revisits purchasing power parity (PPP) theory for 20 African countries using panel asymmetric nonlinear unit root test proposed by Emirmahmutoglu and Omay (2014), through the sequential panel selection method of Chortareas and Kapetanios (2009). While standard panel unit root tests fail to support the PPP, the empirical results from panel asymmetric nonlinear unit root test do support the PPP. However, additional tests reveal that support in all 20 African countries is mostly due to stationarity of the real effective exchange rates of Ghana and Rwanda where the adjustment process towards equilibrium is nonlinear and asymmetric.  相似文献   
86.
In this study, we aim to analyse whether Turkey's 14 major tourist source markets are converging by using monthly data over the period January 1996 to December 2012. To this aim, we use the recently developed two-step Lagrange multiplier (LM) and three-step residual augmented least squares-Lagrange multiplier (RALS-LM) unit root tests that allow for two structural breaks in data. The results indicate that 10 out of 14 markets are converging, meaning that tourism policies and strategies directed at these markets are successful. Furthermore, the break points correspond to the important political, social, natural and economic events such as crisis, earthquake, disease and terrorist attack.  相似文献   
87.
This paper investigates properties of the money demand functions of Group of Six (G6) member countries (Canada, France, Italy, Japan, U.K., and U.S.) using the estimation and inference techniques of panel cointegration. Empirical analyses are conducted by estimating money demand equations of G6 countries individually and as a whole, allowing heterogeneity in individual specific fixed effects across countries through dynamic, nonstationary panel estimation techniques. By using recently developed panel cointegration techniques, the paper contributes to the literature of money demand studies by improving the power performance of the relevant estimation and inference procedures. It reports fully modified OLS (FMOLS) estimation results of the money demand model for different data frequencies, to find varying signs and magnitudes of real income, interest rates and inflation elasticities of money demand for G6 nations.  相似文献   
88.
A thorough study of X party material flow (XPMF), its theory and its applications is conducted in this research. The X material flow concept is an extension of the material flow (MF) theory. To further elucidate that XPMF is one type of MF service model with PMF (party, material, flow) fractal structure and the characteristics of XPMF, we develop the three-pyramid synergetic operational model of XPMF. Through the analysis of several cases, we believe that OIR (Objective relational grade, Information sharing grade, and Resource complementary grade) is the set of order parameters that control and determine the formation of XPMF new structure and its degree of being ordered. Therefore it reveals the mechanism of XPMF formation and evolution. We also provide the principles and the methods for XPMF control.  相似文献   
89.
采用核密度函数和Markov随机过程理论研究了我国省区劳均收入分布的动态演变和发展趋势。研究发现,改革前我国省区劳均收入为多峰分布,其遍历分布为偏向低收入的双峰分布;改革后,劳均收入分布经历了从多峰到单峰再到双峰的演变过程,其遍历分布为偏向高收入的双峰分布。从长期发展趋势看,改革后我国多数地区将会收敛于高收入区间。  相似文献   
90.
钱学斌 《民营科技》2013,(12):124-124
本文主要是用单片机AT89S52为控制核心元件,设计了一个电子琴。核心主控为单片机,与键盘模块、扬声器模块等组成核心控制,主控模块上有16个按键和扬声器。系统稳定性良好,特点是硬件电路简单,软件功能完善,控制系统可靠,性价比较高等,具有一定的实用和参考价值。  相似文献   
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