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本文用对比分析和农諺所作的长期預报效果是值得重視的,在开展长期預报工作中,有显著的参考价值。其中所用的甲子、五行之說是否有科學理論根据,尚无定論,是否能用作預报依据,亦待進一步探討,本刊本着发揚敢想、敢說、敢作的精神,現将全文發表,希望大家討論、补充。 相似文献
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华北平原禹城市耕地变化与驱动力分析(英文) 总被引:2,自引:0,他引:2
Taking Yucheng, a typical agricultural county in Shandong Province as a case, this study applied Logistic regression models to spatially identify factors affecting farmland changes. Using two phases of high resolution imageries in 2001 and 2009, the study obtained the land use and farmland change data in 2001-2009. It was found that the farmland was reduced by 5.14% in the period, mainly due to the farmland conversion to forest land and built-up land, although part of forest land and unused land was converted to farmland. The results of Logistic regressions indicated that location, population growth and farmer income were main factors affecting the farmland conversion, while soil types and pro-curvature were main natural factors controlling the distribution of farmland changes. Regional differences and temporal-spatial variables of farmland changes affected fitting capability of the Logistic re-gression models. The ROC fitting test indicated that the Logistic regression models gave a good explanation of the regional land-use changes. Logistic regression analysis is a good tool to identify major factors affecting land use change by quantifying the contribution of each factor. 相似文献
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华北平原降水的长期趋势分析(英文) 总被引:4,自引:1,他引:3
The North China Plain (NCP) is the most important food grain producing area in China and has suffered from serious water shortages. To capture variation water availability, it is necessary to have an analysis of changing trends in precipitation. This study, based on daily precipitation data from 47 representative stations in NCP records passed the homogeneity test, analyzed the trend and amplitude of variation in monthly, seasonal and annual precipitation, annual maximum continuous no-rain days, annual rain days, rainfall intensity, and rainfall extremes from 1960 to 2007, using the MannKendall (M-K) test and Sen’s slope estimator. It was found that monthly precipitation in winter had a significant increasing trend in most parts, while monthly precipitation in July to September showed a decreasing trend in some parts of NCP. No significant changing trend was found for the annual, dry and wet season precipitation and rainfall extremes in the majority of NCP.A significant decreasing trend was detected for the maximum no-rain duration and annual rain days in the major part of NCP. It was concluded that the changing trend of precipitation in NCP had an apparent seasonal and regional pattern, i.e., precipitation showed an obvious increasing trend in winter, but a decreasing trend in the rainy season (July to September), and the changing trend was more apparent in the northern part than in the southern and middle parts. This implies that with global warming, seasonal variation of precipitation in NCP tends to decline with an increasing of precipitation in winter season, and a decreasing in rainy season, particularly in the sub-humid northern part. 相似文献
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本文介绍了作者研制的可独立于商品化数据库管理系统的地理信息系统(GISID)的前端软件-建库系统的数字化输入、图式符号设计、图形编辑、属性编辑和制图输出等主要内容。然后说明了该系统的主要特点和关键技术,最后讨论了该系统的应用前景、存在的问题及今后的研究方向。 相似文献
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