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1.
Changsha, a typical city in central China, was selected as the study area to assess the variations of ecosystem service value
on the basis of land-use change. The analysis not only included the whole city but also the urban district where the landscape
changed more rapidly in the center of the city. Two LANDSAT TM data sets in 1986 and 2000 and land use data of five urban
districts from 1995 to 2005 were used to estimate the changes in the size of six land use categories. Meanwhile, previously
published value coefficients were used to detect the changes in the value of ecosystem services delivered by each land category.
The result shows that the total value of ecosystem services in Changsha declines from 1 009.28 million per year in 1986 to1 009.28 million per year in 1986 to
938.11 million per year in 2000. This decline is largely attributable to the increase of construction land, and the conversion
from woodland and water body to cropland to keep the crop production. In the five districts, there is $6.19 million decline
in ecosystem service value between 1995 and 2005. Yuelu District has the highest unit ecosystem service value while Yuhua
District has the lowest one. This may be attributed to the greater conversion from cropland and grassland to woodland and
water body with the increase of construction land in Yuelu District. It is suggested that the increase rate of construction
land should be controlled rigorously and the area of woodland and water body should be increased or at least retained in the
study area. 相似文献
2.
1 Introduction Heavy metals like copper, mercury, chromium, cadmium, lead, nickel and zinc cause serious threat to environment, animals and human for their extreme toxicity[1]. Many industries including metal plating, mining, battery, pigment, dyestuff a… 相似文献
3.
4.
酸奶是新疆各少数民族经常食用的一种乳制品。从新疆采集的22个酸奶样品中共分离出56株乳酸菌,通过形态特征观察、生理生化实验、糖发酵实验等传统鉴定方法,结合16S r DNA序列分析对其进行鉴定。结果表明,新疆传统酸奶中菌相构成为德氏乳杆菌(Lactobacillus.delbrueckii subsp.)46株(占总分离株的82%);发酵乳杆菌(Lactobacillus.fermentum)2株(4%);瑞士乳杆菌(Lactobacillus.helveticus)2株(4%);嗜酸乳杆菌(Lactobacillus acidophilus)1株(2%);鸡乳杆菌(Lactobacillus.gallinarum)2株(4%);屎肠球菌(Enterococcus faecalis)1株(2%);耐久肠球菌(Enterococcus canis)2株(4%)。说明新疆传统酸奶中德氏乳杆菌为优势菌。 相似文献
5.
分析不同产地芋头挥发性有机化合物组成差异,并构建芋头产地溯源的可视化指纹图谱。采用气相离子迁移谱法对不同产地芋头的挥发性物质进行测定,结合主成分分析(PCA)实现样品产地的快速区分,进一步筛选芋头中差异挥发性物质。结果表明,在不同产地芋头中,共检测到45个信号峰,鉴定出26种化合物,包括单体和部分化合物的二聚体。主成分分析将芋头分为3类,其中,靖江香沙芋和奉化芋头的挥发性物质较为相似,而与荔浦芋头、沙沟芋头差别很大。异丙醇、2-甲基-乙酸丁酯、辛酸甲酯是区别不同芋头的特征标记物。该方法直观、快速,为地方特色芋头的区分提供了新方法和技术支持。 相似文献
6.
几种面粉添加剂及其作用机理 总被引:4,自引:0,他引:4
阐述了增白剂,品质改良剂(增筋剂,减筋剂,发酵剂),营养强化剂等食品添加剂的作用机理,并对增白剂和强筋剂作了安全性评价。 相似文献
7.
8.
Exploring harmonious development between urbanization and eco-environment based on climate analysis—A study in Changsha,China 总被引:1,自引:0,他引:1
The process of urbanization affects the urban warming. The change of urban warming was investigated by several urbanization
factors in Changsha, China. The data of surface temperature (minimum, maximum and mean) of Changsha were analyzed to understand
the possible effects of urbanization on the climate of this region owing to the population growth, built-up area expansion
and energy consumption increases. The weights of these three factors were calculated by the analytical hierarchy process (AHP).
Then, three weights were simulated with nonlinear method to obtain the urbanization development rate which was utilized to
reveal the influence of the urbanization factors on the surface temperature. The result shows that there is a significant
upward trend in the urban temperatures of Changsha. The temperature increase seems to be closely related to the rate of urbanization
between 1993 and 2008, and there is an evidential increase trend of the influence on urban temperature by urbanization during
16 years. It is a quantifiable approach measuring the relationship between urbanization and urban eco-environment, and can
be applied for the urban sustainability. 相似文献
9.
以高油花生宇花9号和宇花14号为研究对象,以普通花生海花1号和亲本花育20号作为对照,采用溶剂浸提法提取花生油,对花生油的感官品质、理化品质、脂肪酸组成及相对含量进行研究,并通过相关性分析和主成分分析探究花生油脂肪酸组成的关系。结果表明:试验制得的花生油均为黄色、澄清透明的液体,具有花生油固有的滋味和气味。宇花9号和宇花14号花生油酸价、碘值均显著低于亲本花育20号,酸价分别为0.08 mg/g和0.27 mg/g,碘值分别为94.20 g/100 g和93.08 g/100 g。脂肪酸检测结果表明:宇花9号、宇花14号油酸含量高,分别为42.510%和41.976%,油亚比分析结果表明宇花9号、宇花14号更耐贮藏。主成分分析和相关性分析表明,花生油主要脂肪酸为棕榈酸(C16:0)、硬脂酸(C18:0)、亚麻酸(C18:3n3)、花生酸(C20:0)、花生一烯酸(C20:1),单不饱和脂肪酸与多不饱和脂肪酸存在极显著负相关,且与饱和脂肪酸存在极显著正相关,多不饱和脂肪酸与饱和脂肪酸存在极显著负相关。综合以上分析,相对比海花1号和花育20号,推测宇花9号和宇花14号更耐储藏。 相似文献
10.
采用第一原理赝势平面波方法研究迹量元素N在γ-Ni/γ′-Ni3Al相界区域的占位趋势及其对相界断裂强度的影响。结果显示:以气态形式存在的N不易掺杂到Ni/Ni3Al相界,而以固态形式存在的N则很容易被掺进Ni/Ni3Al相界;N在Ni/Ni3Al相界中不仅能稳定存在,而且掺杂到八面体间隙比置换其中的基体原子具有更高的形成能力与结构稳定性;N掺杂将削弱Ni/Ni3Al相界的断裂强度,其中尤以间隙位掺杂最为明显。电子结构分析表明:置换型掺杂时,相界断裂强度的降低可归结为Frenkel缺陷导致的掺杂相界层间电子相互作用的减弱;而间隙位掺杂,除了基体原子间电子相互作用因掺杂原子与基体原子间的强相互作用而减弱外,晶格畸变导致的局域弹性应变能增加也是一个重要的原因。 相似文献