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71.
In our previous work, we searched for superflares on different types of stars while focusing on G-type dwarfs using entire Kepler data to study statistical properties of the occurrence rate of superflares. Using these new data, as a byproduct, we found 14 cases of superflare detection on 13 slowly rotating Sun-like stars with rotation periods of24.5–44 days. This result supports the earlier conclusion by others that the Sun may possibly undergo a surprise superflare. Moreover, we found 12 and se... 相似文献
72.
GEOTAIL卫星于1994年1月15日亚暴期间,在深磁尾(x=96RE)观测到多重等离子体团及与之相对应的高能离子爆,作者以宁静磁尾平衡位形为初态,考虑介质的可压缩性,数值研究亚暴期间磁尾动力学过程.计算结果展现了等离子体团间歇性形成及其运动发展过程.体现了强亚暴事件中储存于碰尾的能量,通过多重等离子体团的排放而逐渐释放的进程.数值结果还表明:持续施加于边界上的晨昏电场及由此引发的驱动重联是导致等离子体团准周期形成的主要因素.此外,作者还考察尾瓣内任一点磁场强度及其分量随时间的演化,它与行进压缩区(TCRs)的观测特征基本相符. 相似文献
73.
I INTRODUCTIONWetland has very important effect on retainingwater and against drought, regUlating climate, controlling soil erosion and so on ac. Today men often attachimportance to economic effect of wetland reclamation,but neglect and destroy other functions and effectswhich result in blind wetland development, a lot ofwetland degeneration. The area of freshwater wetland inthe 1950s was 134 x 10'ha, but in the 1970s 70% hadchanged into farmland (MITSCH, 1993). The area ofwetland in d… 相似文献
74.
Received date: -- Revised date: -- Foundation item: Under the auspices of the National Natural Science Foundation of China 《地理学报(英文版)》2000,(3)
1 Introduction1.1 Introduction to Liaocheng PrefectureLiaocheng
Prefecture lies in northwest of Shandong Province and slightly north to the center of the Huang-Huai-Hai Plain with latitudes between 35(47'N and 37(02'N and longitudes between 115(16'E and 116(32'E. Administratively, it consists of two cities (Liaocheng and Linqing) and six counties (Yanggu, Shenxian, Chiping, Dong'e, Guanxian and Gaotang). It covers a total area of 8590 km2 with a maximum distance of 114 km from eas… 相似文献
75.
Distribution, use pattern and prospects for conservation of medicinal shrubs in Uttaranchal State, India 总被引:1,自引:0,他引:1
The present paper gives an insight into the distribution and use pattern of medicinal shrubs in Uttaranchal State. A total of 222 medicinal and aromatic shrub species have been appended based on secondary information. Euphorbiaceae, Rosaceae, Verbenaceae, and Fabaceae have the highest repre- sentatives of medicinal shrubs. Twenty one families had one species each in medicinal use. Verbenaceae and Euphorbiaceae in the sub-tropical region, Rosaceae in the temperate region, and Ericaceae and Rosaceae in the sub-alpine and alpine regions, respectively, had the highest representatives of medicinal shrubs. The distribution of medicinal shrubs was 42 % in sub-tropical, 29 % in warm temperate, 13 % in cool temperate, 9 % in sub-alpine and 7 % in the alpine region. Of the total species, 70 medicinal shrubs were native to the Himalayas and 22 native to Himalayan region including other Hima- layan countries. The most frequently used plant parts for various ailments were leaves (31 %) and roots (23 %). Most shrubs are being used for the diseases, viz. skin diseases, dysentery, cough, fever, wounds, and rheumatism. The present paper will help in the execution of strategies for promotion and cultivation of medicinal shrubs in Uttaranchal State. 相似文献
76.
1 THE NATURAL ENVIRONMENTAL CHARACTERISTICS The Sanjiang Plain is located in the northeast of Heilongjiang Province, China. Russia borders this region in the north and east. Its total area is 1.088×107ha. The area of plain occupies 61.21%of the total land area and that of hill and mountain amounts to 38.79%of the total land area. It is not only one of the most important regions with large area of fresh water wetlands and with varieties of rare migratory waterfowls, but a… 相似文献
77.
78.
河南既是农业大省又是中国重要的粮食主产区,农用地流转顺畅及适度规模经营对区域经济发展和国家粮食安全产生重要影响。借助于土地使用权评估的基本方法,并使用土地承包经营权的权属特性进行修正,构建了土地承包经营权流转价格模型,并对典型区域沁阳市西万村进行了实证分析。结果表明,土地承包经营权流转价格应该包括经济价格、社会价格和修正价格。价格模型的应用,应甄别理论价格和实际流转费用的区分,农用地流转后经营项目没有转变,流转价格为经济价格和社会保障价格是总和。农用地流转后经营项目发生转变,比如耕地改种经济作物,流转价格则是经济价格、社会价格与修正价格三者的总和。收益分配格局存在复杂性,流转收益应在流出方、流入方、管理者和所有者之间合理、公平分配。政府应建立合理有序的农用地承包经营权流转市场,并以农用地流转市场为载体,构建农用地流转价格体系。 相似文献
79.
A total of 12 indices of temperature extremes and 11 indices of precipitation ex-tremes at 111 stations in southwestern China at altitudes of 285-4700 m were examined for the period 1961-2008. Significant correlations of temperature extremes and elevation in-cluded the trends of diurnal temperature range, frost days, ice days, cold night frequency and cold day frequency. Regional trends of growing season length, warm night frequency, coldest night and warmest night displayed a statistically significant positive correlation with altitude. These characteristics indicated the obvious warming with altitude. For precipitation extreme indices, only the trends of consecutive dry days, consecutive wet days, wet day precipitation and the number of heavy precipitation days had significant correlations with increasing alti-tude owing to the complex influence of atmospheric circulation. It also indicated the increased precipitation mainly at higher altitude areas, whereas the increase of extreme precipitation events mainly at lowers altitude. In addition, the clearly local influences are also crucial on climate extremes. The analysis revealed an enhanced sensitivity of climate extremes to ele-vation in southwestern China in the context of recent warming. 相似文献
80.
土地利用变化空间模拟的进展--CLUE-S模型及其应用 总被引:24,自引:1,他引:24
土地利用变化的空间模拟是进行土地利用情景分析的重要基础。本文在介绍了国际上常用的细胞自控模型(CA)、土地利用变化及效应模型(CLUE)的基础上,重点分析了小尺度土地利用变化及效应模型(CLUE-S)的方法,并以邯郸地区为例进行了案例研究。认为CLUE-S模型采取经验模型的方法,通过建立土地利用空间分配和驱动因子之间的统计关系模拟近期土地利用变化的情景。同时也考虑了不同土地利用方式之间的竞争关系,因此可以较好地模拟小尺度地区的近期土地利用变化情景;考虑到短期或近期土地利用变化的因子主要与人类的社会经济活动有关,而社会经济因子的空间化尚存在一定难度。因此,突破这一瓶颈成为CLUE-S模型发展和应用的关键;CLUE-S模型主要解决的是不同空间尺度上的土地利用空间分配问题,在土地生产潜力评价、土地利用规划等方面具有广阔的应用前景。 相似文献