甘肃农业大学农耕特色库

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唐代西北地区政治地理格局变动研究: 作者： 魏昀 来源： 陕西师范大学 年份： 2009 文献类型： 学位论文 关键词： 唐朝疆域羁縻府州屯田交通; 描述： th about three of culture and materials the country's territory changed a lot. The country's territory was in an extending period before and the An-Shi Armed Rebellion, and once extended to the Central Asia area.At the same time, the Tang government founded the Ji-Mi-Fu-Zhou system in the Western Regions. The situation changed rapidly when the An-Shi Armed Rebellion broke out. Then the central government mobilized the troops in the Western Regions to participating in putting down the Rebellion, so the border defence was weakened. Tu-bo took the chance to occupy a large amount of territory. Almost Long You Area was oppupied by Tu-bo later in Tang Dynasty. The thesis is divided into five chapters: political geography circumstance in northwest area in early Tang Dynasty，including the situation of physical geography and the nation regime; the political geography situation in the extending period of territory from Tai Zong to Gao Zong;the political geography situation in the stable period of territory from Wu-zhou era to An-Shi Armed Rebellion;the political geography situation in the shrinking period of territory after An-Shi Armed Rebellion;relationship between the change of political geography situation and economy and traffic. Conclusion: From A.D. 7th to 9th century，Asia-Erope Continent was a place where Tang, Da-shi and Tu-bo contended for political space. The country's power of politics, economy and military strengthened before An-Shi Armed Rebellion, and part of the Central Asia area belonged to Tang government. The territory reached to an unparalleled scale at that time, which can be divided into three parts: the capital area where Chang-an and Luoyang were located in was the empire's center of politics, culture and military; the Zheng-zhou that around the captals was where the finance of central government stemmed from; the Ji-mi-fu-zhou system Tang government founded in the frontier area was the military buffer zone with nation regimes in vicnity. At the same time, Tu-bo appeared in the stage of history in A.D 7th century. After the King Song-zan-gan-bu unified the Tibet plateau, Tu-bo's power strengthed rapidly and harassed Tang's frontiers inceasingly. The Tang government put the defense police actively into effect so as to resist Tu-bo's aggression and defend country's benefit in Long-you area. When An-Shi Armed Rebellion broke out, Tu-bo took the chance to occupy vast territory of Tang Dynasty, like Minzhou, Lanzhou, Kuozhou, Guazhou, and so on. Eventually, almost all Long-you areas belonging to Tang Dynasty was occupid by Tu-bo. In the field of geopolitics, the national power strengthened in the earlier stage of Tang Dynasty and stronger than Tu-bo. Tu-bo didn't have the strength contending with Tang Dynasty, even harassed the frontier once a while. Until the An-Shi Armed Rebellion, the Tang government had no more advantage and the national power was weakened.; 全文：组织了抵抗,但面对日益强大的吐蕃,已是强弩之末。到唐后期,陇右地区几乎都被吐蕃占有,双方的边界仅维持在陇山一线。本文分为五部分,第一部分介绍唐初西北地区的政治地理格局,包括自然地理概貌和民族政权的分布

陕西白水苹果园土壤元素分布与环境研究: 作者： 董红梅 来源： 陕西师范大学 年份： 2014 文献类型： 学位论文 关键词： 人为富集土壤剖面自然富集元素分布预测模型白水苹果园; 描述： 土壤是人类赖以生存的重要自然资源,而土壤元素的丰缺情况直接影响着农产品的品质和产量。研究土壤元素的组成,不仅能认识土壤元素的垂直分布特征及成因,而且对揭示人类活动的污染强度和影响深度,对改善土壤质量实现农业可持续发展具有重要意义。黄土高原是中国乃至世界优质苹果生产基地之一,但多年种植造成果园土壤质量; 全文：模型。采用单因子和综合指数法对土壤剖面的重金属含量进行了环境评价,利用磁化率和色度对土壤重金属含量进行了快速诊断与预测。获得了以下主要结果与认识： (1)土壤以粉砂为主,pH值为7.0-8.3,呈中

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