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51.
景泰川灌区位于甘肃省北部,景泰县内。1974年景泰电力提水工程建成,最大提水高度406.2米,设计流量10.5米/秒,有效灌溉面积30万余亩。本区为干旱区大陆性气候,年平均降水量186毫米,蒸发量3600毫米,且风沙多。过去由于没有灌溉条件,大面积土地长期荒芜。景电工程的建成,彻底改变了本区的自然面貌和生产条件,短短的十四年间,这里建成了荒漠中的大片绿洲。但是,随着土壤灌溉,灌区的次生盐渍化已经露头。根据第二次土壤普查统计,己经盐化面积30482亩,占总耕地面积的10.16%。因此,充分发挥提黄河水灌溉的效益,并防治土  相似文献   
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53.
李天星 《安徽农业科学》2009,37(31):15624-15629
通过对云南省永仁县直苴村刀耕火种农业的景观生态学研究,发现在一个相当长的时期内,正是刀耕火种使山地民族社区人和森林都实现了自身的可持续发展,并同时实现了二者的和谐发展,但随着人口、资源和环境的变化,刀耕火种存在的条件不断消失,刀耕火种也必然消失,这说明任何一种物质生产方式都有其时空尺度的局限性,都必须以一定的环境条件和资源条件为基础,以区域内生态系统的健康、持续性发展为前提,  相似文献   
54.
Objective To provide information on changes in the social and educational backgrounds of veterinary students over a 10 year period in an effort to determine the extent to which they are representative of the community.
Methods Questionnaires were completed by first-year veterinary students at The University of Queensland in 1985 and 1986 (152 students), and 1995 and 1996 (154), and the data were analysed using the SAS System for Windows.
Results The gender ratio of first-year veterinary students was 50:50 (male:female) in 1985 and 1986 but 10 years later it had changed to 38:62. In 1985 and 1986 77% had come directly from school, with 43% of the total coming from government schools, 17% from Catholic schools and 34% from other private (Independent) schools. A decade later the percentage coming directly from school had decreased to 40%, that from Independent schools increased to 45% and that from cities increased from 53% to 64%. The educational backgrounds of parents varied widely though a high percentage had university degrees; mothers had received less formal education than fathers, and the educational attainments of both parents were higher at the beginning than at the end of the study. More than half (57% initially; 67% 10 years later) the fathers were in professional or managerial occupations, and a similar number (50% initially; 48% 10 years later) of mothers were teachers, nurses or clerks. The number of males from country areas decreased from 26 to 16 over this period.
Conclusion These veterinary students differed from the community generally in that progressively more were female, more were from Independent schools, their parents had more formal education and more of their parents were in professional, managerial or clerical occupations.  相似文献   
55.
自主学习能力对于学习者而言是一项重要技能,是实现终身教育所必备。文中分析了自主学习能力的培养对于少数民族外语学习者的重要性,探讨了在现代信息技术日益改变着教学模式的背景下如何培养少数民族学生的外语自主学习能力。笔者认为,树立以学生为中心的教学理念是实现自主学习能力培养的关键,培养学习动机、学习策略以及利用网络资源的能力是提高学习者自主学习能力的三个重点。  相似文献   
56.
边疆少数民族大学生进入大学后由于言语交流的障碍,导致心理问题的产生。通过对边疆少数民族大学生汉语言语使用情况的抽样调查,进一步了解使其产生交流障碍的言语因素,并对这些因素加以分析,找出边疆少数民族大学生使用汉语言语的难点、排斥情况和言语对心理健康的影响方式,从而更好地培养边疆少数民族大学生进入更大、更先进的言语环境的适应性,使其健康成长。  相似文献   
57.
This study of the pruning of néré (Parking biglobosa) trees in central Burkina Faso included detailed surveys of 83 trees and their owners in 21 villages. Pruning is not widespread, but appears to be a practice with various motives and techniques. The motives are mainly aimed at deliberate management of the trees, in order to enhance their fruit production, and are rarely aimed at reducing tree impact on crop productivity. The characteristics of tree pruning techniques (e.g., frequency, intensity and seasonality) and their corresponding motives appear to change as an adaptation to land degradation processes and the deterioration of tree condition. The results demonstrate that indigenous silvicultural management techniques contribute to a sustainable use of tree resources.
Résumé Cette étude sur la taille du néré (Parkia biglobosa) a été faite par des observations détaillées de 80 nérés et les entretiens avec leurs propriétaires dans 21 villages au Plateau Central du Burkina Faso. La taille du néré n'est pas générale, mais révèle diverses motivations et techniques. La plupart des motivations est orientée vers une gestion consciente de l'arbre en vue d'une amélioration de la production furitière, et rerament en vue d'une reduction de l'influence de l'arbre sur les cultures. Les caracteristiques des techniques de taille (fréquence, intensité, période de taille) et les motivations impliquées paraissent s'adapter à la dégradation de l'environnement et al détérioration de la viabilité des arbres. Les résultats montrent la durabilité des pratiques concernant la gestion des arbres.
  相似文献   
58.
The effects of anthropogenic disturbances on forest structure and plant diversity of secondary forest ecosystems were evaluated based on the classification by site factors in the montane regions of northeastern China. Forty-five sample plots containing 720 sub-plots of overstory species (8 m × 8 m), 1,440 quadrats of understory species (2 m × 2 m), and 1,440 quadrats of herbaceous layer species (1 m × 1 m) were clustered into five groups (G1, G2, G3, G4 and G5) by site variables with Hierarchical Cluster Analysis. Meanwhile, the disturbance levels corresponding to the five groups were determined according to the factors influencing human disturbances (D0-G2, D1-G1, D2-G3, D3-G5, and D4-G4). Species diversities of overstory, understory, herbaceous layer and overall species were evaluated using species number, Margalef index, Pielou index, Shannon–Wiener index, and Simpson index; and β-diversities (Whittaker index, Cody index). Basal area of stands exhibited a decreasing trend along the disturbance level due to a gradual increase in the extraction of timber by the human disturbances. The indices of species diversity suggested that overstory and understory species were distributed evenly among the groups or disturbance levels. There were no absolutely dominant tree species in the secondary forest ecosystems. The differences in site factors and the current disturbance intensities were not intense enough to lead to loose changes in overstory and understory species. The species diversity indices exhibited the maximum values at D3 (G5) for herbaceous layer species; this may suggest that the current disturbance intensities were intense enough to lead the changes of herbaceous layer species. Three rare and endangered species (Juglans mandshurica, Fraxinus mandshurica and Acanthopanax senticosus) were found within the secondary forests. These rare and endangered species appeared in each clustered group or disturbance level, which suggested that the current disturbance intensity in the study area was not strong enough to influence the distribution of rare and endangered species. The current disturbances in the secondary forests may not lead to a decrease in stability and complexity of the overstory and understory species, but the higher disturbance level may be intense enough to change the habitat fitness for the herbaceous species. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized authors.  相似文献   
59.
翟晶晶 《绿色科技》2021,(5):247-249
指出了少数民族地区地处偏僻、地方经济相对落后,要实现“为国家和地方经济发展培养适应生产、建设、管理、服务第一线需要的数以百万计的应用型技术技能人才”的教育目标、助力脱贫攻坚,则践行立德树人的根本任务更为突出。因此,探索了高职旅游英语课程思政的有效路径,并从教师、教材、教法3个角度切入,提出了教师跨学科优化团队建设、教材融合地方少数民族特色研发、教法基于产出导向(POA)拓展教学时空等有效路径。  相似文献   
60.
为给沿淮稻茬麦区小麦高产栽培及品种育种提供依据,在大田条件下,选取沿淮麦区6个高产小麦品种为供试材料,用三次多项式方程对籽粒灌浆过程进行拟合,通过相关性分析对小麦籽粒灌浆参数与粒重的关系进行探究,研究不同小麦品种间产量及其构成因素的差异。结果表明: 6个品种中,安农大1216的产量最高,为8 598.77 kg·hm-²,烟农19最低,产量为6 031.07 kg·hm-²;籽粒灌浆过程中安农大1216粒重最高,成熟期千粒重达到51.4 g,郑麦9023的千粒重最低,为47.78 g;各个品种间灌浆速率存在明显差异。不同小麦品种籽粒灌浆过程均呈“S”型变化,因品种不同,灌浆参数也有所不同,但“R²”均达到0.99以上。相关性分析表明,千粒重与理论最大粒重(W)显著相关,与平均灌浆速率(V)、最大灌浆速率(Vmax)、有效灌浆持续期平均灌浆速率(Vs)、有效灌浆持续期粒重增加值(Ws)和最大灌浆速率出现时间(T)呈正相关但未达显著水平。可见筛选的WVVmaxVs、Ws和T等灌浆参数值较高的小麦品种在该地区种植有利于提高小麦千粒重,增加产量。此外,必须考虑到小麦品种、高效栽培方式、管理手段和协调产量构成三因素,才会最大可能实现小麦高产高效。  相似文献   
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