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261.
对高邮-宝应M4.9地震前湖州台定点形变资料进行了分析,发现其存在趋势异常、短期异常和临震异常。震源机制解结果显示,摆式倾斜仪的倾斜异常的方向与研究区域背景应力场方向一致,形变异常很可能是区域构造应力场改变的反映。 相似文献
262.
钻孔应变仪体应力灵敏系数的影响因素研究 总被引:1,自引:0,他引:1
分别计算了水泥弹性模量、水泥层厚度、钢筒厚度、岩石弹性模量等对钻孔应变仪体应力灵敏系数的影响,得出:1)在水泥弹性模量小于某个固定值时,体应力灵敏系数随水泥弹性模量的增大而增大,大于这个值时,体应力灵敏系数又随水泥的弹性模量增大而变小;2)当水泥层厚度比N<2时,体应力灵敏系数变化剧烈,受水泥层厚度影响较大;3)体应力灵敏系数随钢筒厚度及岩石弹性模量的增大而变小。 相似文献
263.
���������ϲ��α������Ĺ�ϵ 总被引:1,自引:0,他引:1
?????????????????????????1985??2006?????????????????????α??????????????????????????????????????????????????????????6???????????????????????????????????????????????????????л??????????????5?????????????????? 相似文献
264.
265.
Estimation on Aesthetic Value of Tourist Landscapes in a Natural Heritage Site: Kanas National Nature Reserve, Xinjiang, China 总被引:1,自引:0,他引:1
Most world natural heritage sites are designated partly by reason of their prominent aesthetic values in accordance with Article Ⅶ of World Natural Heritage Convention.In this paper, the aesthetic values of Kanas National Nature Reserve, which has potential for such designation, was analyzed quantitatively using scenic beauty estimation(SBE).The landscapes of 19 representative scenic spots in the Kanas National Nature Reserve in summer and autumn were selected as the objects of evaluation.The contributions of different landscape factors to the aesthetic value of the Kanas National Nature Reserve were revealed using a multivariate quantitative model.The main factors affecting the aesthetic value were waterscapes, vegetation, mountains, folk culture and the tourist environment.The t-test and F-test results are extremely significant.According to the results, some suggestions were given for conserving the landscapes in the Kanas National Nature Reserve. 相似文献
266.
???????????????????У?????????????????????????????????????????????????????????????????????????????????????GPS??InSAR?????????????е??????÷?????????????????????????????????Ч???????????????????????????? 相似文献
267.
Soil moisture, a critical variable in the hydrologic cycle, is highly influenced by vegetation restoration type. However, the relationship between spatial variation of soil moisture, vegetation restoration type and slope length is controversial. Therefore, soil moisture across soil layers (0-400 cm depth) was measured before and after the rainy season in severe drought (2015) and normal hydrological year (2016) in three vegetation restoration areas (artificial forestland, natural forestland and grassland), on the hillslopes of the Caijiachuan Catchment in the Loess area, China. The results showed that artificial forestland had the lowest soil moisture and most severe water deficit in 100-200 cm soil layers. Water depletion was higher in artificial and natural forestlands than in natural grassland. Moreover, soil moisture in the shallow soil layers (0-100 cm) under the three vegetation restoration types did not significantly vary with slope length, but a significant increase with slope length was observed in deep soil layers (below 100 cm). In 2015, a severe drought hydrological year, higher water depletion was observed at lower slope positions under three vegetation restoration types due to higher transpiration and evapotranspiration and unlikely recharge from upslope runoff. However, in 2016, a normal hydrological year, there was lower water depletion, even infiltration recharge at lower slope positions, indicating receiving a large amount of water from upslope. Vegetation restoration type, precipitation, slope length and soil depth during a rainy season, in descending order of influence, had significant effects on soil moisture. Generally, natural grassland is more beneficial for vegetation restoration than natural and artificial forestlands, and the results can provide useful information for understanding hydrological processes and improving vegetation restoration practices on the Loess Plateau 相似文献
268.
Stable isotope values of oxygen(~(18)O) and hydrogen(~(2)H) of surface waters were used to study the origin and environmental significances in the Issyk-Kul basin of Kyrgyzstan in Central Asia, which is the most important intermountain basin in the modern Tien Shan orogen. This study is the first analysis of hydrochemical spatial differentiation in the stable isotopes of surface waters in this watershed.75 samples were collected from rivers, springs, lakes,rain and snow during the rainy season in July and August of 2016. Stable isotopes of ~(18)O and ~(2)H were studied for all samples, and cation ratios(Sr/Ca and Mg/Ca) were also determined for lake water samples.Stable isotope values from precipitation scattered around the Local Meteoric Water Line(determined from Urumqi Station of the global network of isotopes in precipitation(GNIP)), together with values of the Deuterium excess parameter(d) from 15.3‰ to30.5‰, with an average of 19.8‰, indicating that the moisture sources are primarily from regions with low relative humidity. The δ~(18)O and δ~(2)H values were significantly different between the river and lake samples, indicating that regional evaporation caused the isotopic enrichment of lake water. Geospatial autocorrelation, measured by Moran's I coefficient,indicated weak spatial autocorrelation within stable isotopes of oxygen and hydrogen in the surface waters of the studied area, which is primarily an effect of climate during the water chemistry evolution. The cation ratios Sr/Ca and Mg/Ca in lake water samples were not correlated with the concentration of total dissolved solids, but did show correlation with stable isotopic values, which is significant for paleoenvironmental reconstruction. 相似文献
269.
Weiwei Chen Shichun Zhang Quansong Tong Xuelei Zhang Hongmei Zhao Siqi Ma Aijun Xiu Yuexin He 《中国地理科学(英文版)》2018,28(5):836-850
Northeast China experiences severe atmospheric pollution, with an increasing occurrence of heavy haze episodes. However, the underlying forces driving haze formation during different seasons are poorly understood. In this study, we explored the spatio-temporal characteristics and causes of haze events in Northeast China by combining a range of data sources(i.e., ground monitoring, satellite-based products, and meteorological products). It was found that the ‘Shenyang-Changchun-Harbin(SCH)'city belt was the most polluted area in the region on an annual scale. The spatial distribution of air quality index(AQI) values had a clear seasonality, with the worst pollution occurring in winter, an approximately oval-shaped polluted area around western Jilin Province in spring, and the best air quality occurring in summer and most of the autumn. The three periods that typically experienced intense haze events were Period I from mid-October to mid-November(i.e., late autumn and early winter), Period II from late-December to February(i.e., the coldest time in winter), and Period III from April to mid-May(i.e., spring). During Period I, strong PM_(2.5) emissions from seasonal crop residue burning and coal burning for winter heating were the dominant reasons for the occurrence of extreme haze events(AQI 300). Period II had frequent heavy haze events(200 AQI 300) in the coldest months of January and February, which were due to high PM_(2.5) emissions from coal burning and vehicle fuel consumption, a lower atmospheric boundary layer, and stagnant atmospheric conditions. Haze events in Period III, with high PM_(10) concentrations, were primarily caused by the regional transportation of windblown dust from degraded grassland in central Inner Mongolia and bare soil in western Jilin Province. Local agricultural tilling could also release PM_(10) and enhance the levels of windblown dust from tilled soil. Better control of coal burning, fuel consumption, and crop residue burning in winter and autumn is urgently needed to address the haze problem in Northeast China. 相似文献
270.
Yuanqin Xu Lejun Liu Hang Zhou Baoqi Huang Ping Li Xiudong Ma Feiyin Dong 《中国海洋大学学报(英文版)》2018,17(1):147-155
In this paper, we take DLW3101 core obtained at the top of the canyon(no landslide area) and DLW3102 core obtained at the bottom of the canyon(landslide area) on the northern continental slope of the South China Sea as research objects. The chronostratigraphic framework of the DLW3101 core and elemental strata of the DLW3101 core and the DLW3102 core since MIS5 are established by analyzing oxygen isotope, calcium carbonate content, and X-Ray Fluorescence(XRF) scanning elements. On the basis of the information obtained by analyzing the sedimentary structure and chemical elements in the landslide deposition, we found that the DLW3102 core shows four layers of submarine landslides, and each landslide layer is characterized by high Si, K, Ti, and Fe contents, thereby indicating terrigenous clastic sources. L1(2.15–2.44 m) occurred in MIS2, which is a slump sedimentary layer with a small sliding distance and scale. L2(15.48–16.00 m) occurred in MIS5 and is a debris flow-deposited layer with a scale and sliding distance that are greater than those of L1. L3(19.00–20.90 m) occurred in MIS5; its upper part(19.00–20.00 m) is a debris flow-deposited layer, and its lower part(20.00–20.90 m) is a sliding deposition layer. The landslide scale of L3 is large. L4(22.93–24.27 m) occurred in MIS5; its upper part(22.93–23.50 m) is a turbid sedimentary layer, and its lower part(23.50–24.27m) is a slump sedimentary layer. The landslide scale of L4 is large. 相似文献