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101.
The primary goal of Chinese agricultural development is to guarantee national food security and supply of major agricultural products. Hence, the scientific work on agricultural monitoring and early warning as well as agricultural outlook must be strengthened. In this study, we develop the China Agricultural Monitoring and Early-warning System(CAMES) on the basis of a comparative study of domestic and international agricultural outlook models. The system is a dynamic and multi-market partial equilibrium model that integrates biological mechanisms with economic mechanisms. This system, which includes 11 categories of 953 kinds of agricultural products, could dynamically project agricultural market supply and demand, assess food security, and conduct scenario analysis at different spatial levels, time scale levels, and macro-micro levels. Based on the CAMES, the production, consumption, and trade of the major agricultural products in China over the next decade are projected. The following conclusions are drawn: i) The production of major agricultural products will continue to grow steadily, mainly because of the increase in yield. ii) The growth of agricultural consumption will be slightly higher than that of agricultural production. Meanwhile, a high self-sufficiency rate is expected for cereals such as rice, wheat, and maize, with the rate being stable at around 97%. iii) Agricultural trade will continue to thrive. The growth of soybean and milk imports will slow down, but the growth of traditional agricultural exports such as vegetables and fruits is expected to continue.  相似文献   
102.
This study aims to determine the authenticity of the geographical origin of rice using inductively coupled plasma atomic emission spectroscopy (ICP-AES) and chemometrics. The profiles of 25 elements in brown rice measured by ICP-AES were subjected to data-mining processes, including principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA). PLS-DA clearly discriminated the geographical origin of rice samples grown in three countries. Eleven elements (Cu, Ag, Zn, Cr, Ca, Ba, Cd, Bi, K, Pb, and In) significantly contributed to the ability to discriminate the geographical origin of the rice. These results demonstrate the use of multielement profiling combined with chemometrics as a tool for discriminating food origins. This study extends our knowledge about the applications of both multielement profiling and chemometrics for the determination of food authenticity, and thus can be useful for controlling the geographical origin of rice by governmental administration and protecting consumers from improper domestic labeling.  相似文献   
103.
ArcView GIS中地图要素的自动生成   总被引:2,自引:0,他引:2  
为了提高GIS输出的质量,提供了在ArcView GIS中自动生成地图数学要素的算法和程序。该程序用Avenue语言编写。为了使程序简洁、高效,采用了调用动态连接库技术,把复杂的计算部分编写为动态连接库,在ArcView GIS中调用。  相似文献   
104.
福建省森林景观资源质量评价   总被引:3,自引:0,他引:3  
应用改进的投影寻踪技术建立森林景观资源评价模型,可把各森林景观资源多维分类指标综合成一维投影值。投影值越大,表示该森林景观资源景观价值越大,因此,可以根据投影值的大小,对森林景观资源样本集进行合理区划。改进的投影寻踪技术用于景观资源分级与区划,其优化时间短、投影函数能达到最优,投影寻踪效果理想,简单可行,可操作性强。通过由样本数据驱动的改进的投影寻踪技术,建立福建省阔叶林森林景观资源评价模型,并结合聚类分析进行等级划分,福建省阔叶林景观资源等级划分为三级较为适宜。  相似文献   
105.
采用扫描图像与Photoshop图像处理软件结合的方法研究柽柳、柠条、红砂和珍珠的叶片投影面积与叶干质量之间的关系,结果表明:柽柳、柠条和红砂叶投影面积与叶干质量呈线性相关;红砂、柽柳、柠条在生长季单位叶面积所积累的叶干质量分别为(0.0840±0.0031)、(0.0610±0.0011)、(0.0366±0.0007)g/cm2,红砂和柽柳分别是柠条的2.30和1.67倍;珍珠的叶片是多浆汁叶,形状极不规则,不能利用日前的扫描仪计算出它的投影面积;柽柳在不同环境下生长时的叶片投影面积与叶干质量的关系均为线性相关且差异不显著,表明这种线形关系不受生长环境的影响。因此,可以用叶干质量代替叶面积来研究这些荒漠植物的光合作用特性。  相似文献   
106.
投影寻踪回归模型在大豆食心虫虫食率预测中的应用   总被引:5,自引:0,他引:5  
大豆食心虫的虫食率受越冬基数、气象条件等多种因素的影响,是一个复杂的非线性非正态系统,文章采用投影寻踪回归新技术,建立了大豆食心虫虫食率的预测模型,对历史值的拟合和对预留值的预测效果均令人满意,可以作为大豆虫害预测的一种新手段。  相似文献   
107.
多目标决策灰色投影法在水土保持综合效益评价中的应用   总被引:2,自引:2,他引:0  
张传珂 《中国农学通报》2013,29(11):164-167
运用灰色系统理论和矢量投影原理,建立了水土保持综合效益评价多目标决策灰色关联投影模型,旨在探讨多目标决策灰色关联投影法在水土保持综合效益评价中的应用。研究表明,利用多目标决策灰色关联投影法进行水土保持综合效益评价是有效的,具有应用和推广价值。  相似文献   
108.
Ceratocystis platani was detected at several locations in the European side of Istanbul, causing severe dieback and mortality, mainly on Platanus × acerifolia imported from Italy approximately 160 years ago, but also on Platanus orientalis. In the work reported here, the causal agent of the dieback and mortality was identified based on morphological characteristics in culture and internal transcribed spacer (ITS) sequencing, confirming the presence of C. platani in Turkey. All analysed C. platani isolates from Istanbul shared the same ITS sequence with European C. platani strains available in the NCBI, but differed from other species previously ascribed to the Ceratocystis fimbriata species complex. Pathogenicity of C. platani was proven by inoculation onto 25‐cm‐long and 4–9 mm diam. P. orientalis twigs and the causal agent reisolated from symptomatic tissues. In a survey of 976 Platanus in streets and parks of Istanbul, 26.5% of trees showed symptoms of C. platani infections, whilst 5.6% were dead. The proportion of symptomatic trees was higher where management interventions, such as topping or pruning and felling infected trees had been carried out.  相似文献   
109.
110.
Trees are able to respond to their local biotic and abiotic environment with morphological adjustments which improve resource acquisition and, thus, growth. In forests, light is broadly recognised as one of the major factors determining growth, and morphological responses comprise changes in crown architecture and stem stature. On sloping terrain, the interplay of phototropism and gravitropism may further affect morphological growth characteristics. However, different tree species are expected to show species-specific responses. In this study, we analysed three growth characteristics of tree individuals belonging to four species of two functional groups (evergreen: Schima superba, Castanopsis eyrei, deciduous: Quercus serrata var. brevipetiolata, Castanea henryi) in a species-rich Chinese subtropical forest. Crown projection area, relative crown displacement and stem inclination were related to biotic (local species richness, functional richness, competition, stand age) and abiotic (slope aspect and inclination, soil depth) variables in the local neighbourhood of the tree individuals. We hypothesised that (i) there are species-specific differences in the morphological response of crown architecture and stem stature and (ii) that crown size and asymmetry as well as stem inclination are influenced by both, biotic and abiotic factors. In contrast to our expectations we were unable to reveal any species-specific differences in any of the three growth characteristics. The results of mixed effects models showed that crown area was mainly affected by the target tree's dbh and biotic variables related to neighbours (competition, functional diversity), whereas stem inclination was mainly influenced by slope. Relative crown displacement was influenced by both, biotic and abiotic variables. We conclude that growth responses resulting in crown displacement and stem inclination seem to be an important mechanism to ameliorate foraging for light in our study area, but that these responses appear to be species-independent. The interplay of stem inclination and crown displacement allows for a plastic response of tree individuals in biotically and abiotically heterogeneous environments. Our results indicate that forest management in this region should focus on functionally diverse stands which are promoting crown area positively resulting in increased growth rates of individual trees.  相似文献   
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