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1.
Ecological ravages, environmental pollution, and the developmental problems of regional ecology, economy, and society are not geographical restrictions. The synergistic development of the ecology-economy-society system in forestry was quantitatively assessed by system theory and synergistic dynamic models, illustration of the metering principle and corresponding theory, assessing and quantizing synergistic development status of ecology-economy-society system, and the orderliness of the subsystem of the last decade. The orderliness of the ecology and ecological subsystems developed unstably with an increasing trend. The eco-environment construction and eco-conservation achievement of forestry in China are effective and need to be maintained. The industry structure should be improved to promote the growth of the forestry economy. The society subsystem development is increasing but is not at a high level, which indicates that the public demand to ecological service was not satisfied. The theoretical analysis and numerical examples show that the development of the forestry system has a good development state. The synergy changes of forestry system in the 0 to 0.951 range, which is in the intermediate degree of synergy during this period. It still needs much improvement on efficiency of synergy. The orderliness and the relationship among the subsystems of forestry should be improved in future. 相似文献
2.
Zou Jianbo 《保鲜与加工》1992,(4)
In this paper, the concept of basic for linear vector extreme value problem is introduced in the partially ordered vector space. Some properties and results of the linear programming are generalized. And the existaence therom of basic optimal solution is proved. 相似文献
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用有界线性算子代替压缩常数,在序Banach空间中引入了几种压缩型映射,并证明了相应的不动点定理. 相似文献
4.
杉木生长过程特征和生长期划分 总被引:4,自引:0,他引:4
本文用典型分析方法研究了浙江湖州不同立地条件下杉木胸径、树高和材积的生长过程特征。在目前的栽植密度范围内,立地条件愈好,该边缘产区的杉木生长冲劲愈大,各生长指标的连年生长量高峰出现愈早,持续时间相应愈长,具有典型的“冲劲大,后劲小”的特点。而立地较差的林分,连年生长量高峰不明显,其平均生长量基本处于低水平的缓慢增长状态。用有序样本聚类法进行了杉木胸径、树高和材积的生长阶段划分。结果表明该3个生长指标均可分为4个生长阶段,即幼树阶段、速生阶段、干材阶段和滞长阶段。 相似文献
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We tested whether a ‘Lockerbraunerde’ from the heights of the Zittauer Gebirge in Eastern Saxony exhibited andic properties and classified it according to the rules of the World Reference Base for Soil Resources (WRB, 1998). To achieve this, we characterized a selected soil by means of routine soil analysis; selective dissolution procedures; X‐ray diffraction (XRD); X‐ray fluorescence (XRF), and Transmission Electron Microscopy (TEM). We used field criteria (Thixotropy; NaF‐field test) to obtain a map of the spatial distribution of soils with potential andic properties. We found that the soil fulfilled all requirements to be classified as an Andosol. The composition of the colloidal phases was exactly intermediate between sil‐andic and alu‐andic. At the same time, the soil had a spodic horizon [determined through the depth function of the Alo+½Feo criterion]. As there was no indication of vertical translocation of metal‐organic complexes, but sufficient evidence to suggest the downward movement of mobile Al/Si‐phases, we maintain to classify the soil as an Endoskeleti‐Umbric Andosol and propose the existence of a pedogenetic pathway intermediate between Podsolisation and Andosolization. We conclude that the spodic horizon in the WRB is not well defined because of the dominance of the Alo+½Feo criterion over morphological evidence. We further suggest the German soil taxonomy to be modified to better represent soils containing short range order minerals. 相似文献
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二维空间完备性基本定理的相互证明 总被引:1,自引:1,他引:0
平面上的5个定理,闭区域套定理,有限覆盖定理,聚点定理,致密性定理及Cauthy准则,刻画了R2的完备性,构成了二元函数极限理论的基础.分别以闭区域套定理,有限覆盖定理,聚点定理为基础,证明其它定理,体现了这5个定理之间的相互等价. 相似文献
10.
为保持绿豆生产的可持续发展,稳定绿豆生产者的风险态度,使其在生产中降低风险投入的同时增加生产效益,利用黑龙江省213户绿豆生产者的调研数据,运用有序Probit模型对黑龙江省绿豆生产者风险偏好的影响因素进行分析。结果表明:从事绿豆种植年限、绿豆市场价格、退休后继续从事绿豆种植、主粮(玉米、大豆、水稻)种植面积占比增加均对不同程度的风险态度有影响。为稳定生产者的风险态度,提出了提高生产者们对绿豆种植风险的意识水平,多渠道加强培训;鼓励达到退休年龄的生产者继续从事绿豆种植;建议国家农业相关部门提高对主要粮食作物的补贴或惠民政策标准及价格的调控等建议。 相似文献