博弈架构下我国食品安全问题研究

界定了商品真假(食品是否安全)的一般内涵,分别对单商家、双商家、多商家商品出售进行了博弈分析,表明在无相关约束机制下,商家出售假货(问题食品)是博弈的必然结果,会使食品安全问题日益突出。提出了解决食品安全问题的博弈路径:需引入健全有效的监管机制,改变原有的博弈结构,食品安全问题自然会得到解决;另外,道德机制的引入,使全社会流淌着道德的血液,是解决该问题的一个低成本甚至无成本的补充措施。     

平朔露天矿区土地征用对搬迁农民生活水平的影响分析

采用实地调查、类比分析、系统回顾相结合的方法,对平朔矿区已搬迁的安太堡村、白辛窑村、上窑村、西易村居民的生活条件进行了调查研究,结果表明:被征地农民得到一定土地补偿后居住条件有了较大改善。采矿也给农民提供了再就业机会,农民可以依托矿区开展与矿业发展有关的煤层剥离、洗煤、运输、种植及多种经营活动,经济收入有了较大提高。但部分老少农民虽然居住条件得到了改善,但因失去了做为基本生活保障的土地,又无其它就业渠道,生活水平受到了影响。这种情况随着采矿规模的不断扩大,矛盾愈来愈突出。因此,继续开展土地复垦解决复垦土地使用权的流转,已成为保持矿区社会稳定、解决搬迁农户的再就业问题和工农业可持续发展的重要措施。     

Climate variability during the past 2,000 years and past economic and irrigation activities in the Aral Sea basin

The lake level history, here based on the relative abundance of Ca (gypsum), is used for tracing past hydrological conditions in Central Asia. Lake level was close to a minimum before approximately a.d. 300, at about a.d. 600, a.d. 1220, a.d. 1400 and since 1960s it is lowering again. Lake water level was lowest during the fourteenth or early fifteenth centuries as indicated by a coeval settlement, which today is still under water near the well-dated mausoleum of Kerderi. Pollen data from riparian vegetation indicate generally wet conditions between a.d. 400 and a.d. 900, intermitted by short intervals with drier conditions (AD 550–600; a.d. 650–700) and riverbanks were again dry from a.d. 900–1150, a.d. 1450–1550, and from a.d. 1970 onward moisture decreased steadily. Irrigation activities were at a maximum between 300 b.c. and a.d. 300 (Classical Antiquity) and between a.d. 800 and a.d. 1300 (Medieval Age) and after a.d. 1960.     

不同光合途径植物红砂和珍珠猪毛菜幼苗对氮沉降及降水变化的光合响应

氮素和水分是影响植物光合特性的重要因素,而不同光合途径植物对水、氮的响应能反映出植物与环境的关系。为探究氮沉降和降水变化对C₃植物和C₄植物生长方式的影响,以C₃植物红砂（Reaumuria soongorica）和C₄植物珍珠猪毛菜（Salaola passerina）为研究对象,利用盆栽试验,设置不同氮沉降水平（0 g·（m²·a）^-1,4 g·（m²·a）^-1,8 g·（m²·a）^-1）和不同降水处理（W-30%,W,W+30%）,比较两种植物单生和混生下的光合色素、光合气体交换参数和叶绿素荧光参数等的差异。结果表明：水氮耦合使红砂和珍珠猪毛菜光合能力均增强,且在降水增加30%和施氮量8 g·（m²·a）^-1时达最大;红砂的叶绿素、净光合速率分别最大可增加3.63倍、1.19倍,珍珠猪毛菜最大分别增加0.95倍和1.13倍。二者混生显著提高红砂的光合能力,而珍珠猪毛菜的竞争加强,氮水耦合可显著减弱竞争强度,说明在未来氮沉降和降水增加环境下,有利于红砂-珍珠猪毛菜混生群落的发展。     

清代山西乡村聚落的形态和住宅形式

清代山西乡村集居型聚落集中于山西中部、南部和东南部河谷盆地,以阶状、带状和围墙状聚落形状为多;山西北部、东南部和西部山地、黄土丘陵地带,聚落多以小规模散居型聚落为主。清代山西乡村聚落主要有窑洞、茅草屋、砖瓦房、木屋和石屋等住宅形式,以窑洞分布最为普遍,受乡村社会经济条件的制约,清代山西乡村民众的住宅总体上较为简陋。     

大直径扩底桩的沉降变形控制设计法

本文对大直径扩底桩的竖向承载力和沉降变形进行了探讨,提出了按沉降变形控制设计大直径扩底桩基础的方法和相应的计算公式,按本文提出方法得到的计算结果与工程实测值符合较好,该方法可供工程设计参考。     

农业科研单位财务结算中心运行框架新探究

随着财政管理体制的重大变革,以及单位本身加强内部控制和风险管理需要,建立一个科学合理的财务结算中心运行框架非常必要。本文以资金控制为核心,在岗位设置、流程控制等方面对如何构建财务结算中心设计了一套基本运行框架,并提出了应注意的问题。     

Allometric equations for estimating the aboveground volume of five common urban street tree species in Daegu,Korea

Quantifying urban tree biomass and carbon (C) storage by using allometric equations is required for various studies such as assessing the inventory, modelling, and measuring ecosystem services of urban trees. However, the lack of urban-specific allometric equations leads to uncertainty when estimating urban tree biomass and C storage. Therefore, we followed a nondestructive approach and developed allometric equations specifically for Acer buergerianum Miq., Ginkgo biloba L., Platanus orientalis L., Prunus yedoensis Matsum., and Zelkova serrata (Thunb.) Makino in Daegu, Korea. Diameter at breast height (DBH)-based and DBH-and-height-based allometric equations were highly accurate at estimating the aboveground volume (R² > 0.92), while the allometric equations for P. orientalis and Z. serrata developed for traditional forests overestimated volume by 68% and 427%, respectively. The addition of a height variable into the DBH-based allometric equations did not increase the reliability of the allometric equations at a local level. The mean aboveground C storage of urban street trees was 24.9 Mg C/ha except for P. orientalis with a mean of 69.7 Mg C/ha, and the total aboveground C storage of urban street trees in Daegu was 10.6 Gg C. Alternatively, a generalized allometric equation which compiled species-specific equations can be applied for large-scale estimation. The generalized equations developed in this study and those found in the literature may suggest a constant value (～2.3–2.4) for the scaling exponent in the generalized equations. Allometric equations developed from natural or artificial stands may overestimate the volume of urban street trees; therefore, estimating urban tree biomass and C storage requires urban-specific allometric equations.     

珠江三角洲沙田文化景观中的堤围与聚落研究

沙田是珠江三角洲海陆交接地带特殊的地理单元,在人力围垦与自然淤积相互作用下,构成了水网互通、顺水而居、稻作发达的文化景观。通过历史文献、田野调研、历史信息对比等研究方法,发现堤围和聚落是构成沙田文化景观的两个突出要素,呈现空间格局基本保持稳定,要素形态由单一至复杂的发展过程,即为"空间连续、要素变化"的特点,其变迁过程中凝练的生存智慧与生态智慧具有重要的现实意义,另可为有效保护和展示沙田文化景观提供参考。     

巴蜀传统古城镇景观保护措施的研究

结合实例详细解读了巴蜀城镇所具有的景观特征,针对当前城市化给城镇景观带来的消极影响,提出健全法律体系、尊重自然生态环境、延续城镇历史文化风貌、发展文化旅游产业等对策。