Current Location:home > Browse

Subjects

Institution

1. chinaXiv:202011.00126 [pdf]

Morphological characteristics and dynamic changes of seif dunes in the eastern margin of the Kumtagh Desert, China

PANG,Yingjun; WU,Bo; LI,Yonghua; XIE,Shengbo
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

The seif dune field over the gravel desert surface in the eastern margin of the Kumtagh Desert is a valuable experimental site for the observation of dune formation and dynamics. We used high-resolution remote sensing and station observation approaches, combined with wind and grain size data, to study the characteristics of the aeolian environment and the morphologies of and dynamic changes in seif dunes. We observed the ratio of the resultant drift potential (RDP) to the drift potential (DP), which was 0.37, associated with an obtuse bimodal wind regime. The drift potentials in the west-northwest (WNW) and east-northeast (ENE) directions were dominant, and the angle between the two primary DP directions was 135.00°. The dune orientations ranged from 168.75°–213.75°, which were parallel to the resultant drift direction (186.15°). The dune lengths ranged from 51.68 to 1932.11 m with a mean value of 344.91 m. The spacings of the dunes ranged from 32.34 to 319.77 m with a mean value of 93.39 m. The mean grain size of the sediments became finer, and the sorting became better from upwind tail to downwind tip, which indicated that the sediment of the seif dunes in the study region may be transported from northward to southward. The rate of increase in the length, the mean longitudinal migration rate of the dune tail, and the mean longitudinal extension rate of the dune tip (also called elongation rate) were 4.93, 4.63, and 9.55 m/a, respectively. The mean lateral migration vector of the seif dunes was approximately 0.11 m/a towards the west (–0.11 m/a), while the mean amplitude of lateral migration was 0.53 m/a, ignoring the direction of lateral migration. We found that the seif dune field formed first beside seasonal rivers, which can provide sediment, and then expanded downwind.

submitted time 2020-11-25 From cooperative journals:《Journal of Arid Land》 Hits0Downloads0 Comment 0

2. chinaXiv:202011.00127 [pdf]

Assessing the effects of vegetation and precipitation on soil erosion in the Three-River Headwaters Region of the Qinghai-Tibet Plateau, China

HE,Qian; DAI,Xiao'ai; CHEN,Shiqi
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Soil erosion in the Three-River Headwaters Region (TRHR) of the Qinghai-Tibet Plateau in China has a significant impact on local economic development and ecological environment. Vegetation and precipitation are considered to be the main factors for the variation in soil erosion. However, it is a big challenge to analyze the impacts of precipitation and vegetation respectively as well as their combined effects on soil erosion from the pixel scale. To assess the influences of vegetation and precipitation on the variation of soil erosion from 2005 to 2015, we employed the Revised Universal Soil Loss Equation (RUSLE) model to evaluate soil erosion in the TRHR, and then developed a method using the Logarithmic Mean Divisia Index model (LMDI) which can exponentially decompose the influencing factors, to calculate the contribution values of the vegetation cover factor (C factor) and the rainfall erosivity factor (R factor) to the variation of soil erosion from the pixel scale. In general, soil erosion in the TRHR was alleviated from 2005 to 2015, of which about 54.95% of the area where soil erosion decreased was caused by the combined effects of the C factor and the R factor, and 41.31% was caused by the change in the R factor. There were relatively few areas with increased soil erosion modulus, of which 64.10% of the area where soil erosion increased was caused by the change in the C factor, and 23.88% was caused by the combined effects of the C factor and the R factor. Therefore, the combined effects of the C factor and the R factor were regarded as the main driving force for the decrease of soil erosion, while the C factor was the dominant factor for the increase of soil erosion. The area with decreased soil erosion caused by the C factor (12.10×103 km2) was larger than the area with increased soil erosion caused by the C factor (8.30×103 km2), which indicated that vegetation had a positive effect on soil erosion. This study generally put forward a new method for quantitative assessment of the impacts of the influencing factors on soil erosion, and also provided a scientific basis for the regional control of soil erosion.

submitted time 2020-11-25 From cooperative journals:《Journal of Arid Land》 Hits0Downloads0 Comment 0

3. chinaXiv:202011.00124 [pdf]

甘肃定西通渭县声调声学研究

冼诗晴
Subjects: Linguistics and Applied Linguistics >> Linguistics and Applied Linguistics

通过对通渭方言的单字和双字组语音进行声学分析,提取基频参数研究该方言的声调模式。实验结果表明,通渭方言有三个单字调平声、上声、去声诟值分别为23、52、44。双字组声调模式出去轻声之外共有13种,在前后字都有发生,其中平声连读变调模式最为复杂,能够从连读变调模式中分别阴平和阳平,上声除了首还可能在发声方法上存在与葫母相关的嘎裂特征,去声无变调。

submitted time 2020-11-25 Hits35Downloads19 Comment 0

4. chinaXiv:201711.02435 [pdf]

2-Aminopyrimidine Derivatives as New Selective Fibroblast Growth Factor Receptor 4 (FGFR4) Inhibitors

Mo, Cheng
Subjects: Biology >> Ecology

A series of 2-aminopyrimidine derivatives were designed and synthesized as highly selective FGFR4 inhibi-tors. One of the most promising compounds 2n tightly bound FGFR4 with a Kd value of 3.3 nM and potently inhibited its enzymatic activity with an IC50 value of 2.6 nM, but completely spared FGFR1/2/3. The compound selectively suppressed proliferation of breast cancer cells harboring dysregulated FGFR4 signaling with an IC50 value of 0.38 μM. Furthermore, 2n exhibited extraordinary target specificity in a Kinome-wide screen against 468 kinases, with S(35) and S(10) selectivity scores of 0.01 and 0.007 at 1.0 μM, respectively.

submitted time 2020-11-24 Hits792Downloads427 Comment 0

5. chinaXiv:202011.00114 [pdf]

精神分析的主体间转向:理论特征与分歧

张巍; 郭本禹
Subjects: Psychology >> History of Psychology

主体间理论是当代精神分析领域最重要的取向之一。与更传统的精神分析相比,其理论特征表现为从区分“内/外”空间到强调“之间”的空间、从“主体—客体”关系到“主体—主体”关系、从顿悟到行动、从基础主义和实证主义到诠释学和建构主义。当前,精神分析的主体间转向几乎遍及各个流派,广泛影响了北美洲、欧洲和拉丁美洲的诸多分析师。未来的主体间理论需要保持开放的态度,持续与先前的理论、临床资料和其他学科领域对话。

submitted time 2020-11-24 Hits91Downloads26 Comment 0

6. chinaXiv:202011.00112 [pdf]

城镇化与经济发展的时空相互作用机制研究——以新疆为例

张亚如
Subjects: Geosciences >> Geography

运用城镇化率代表新疆地区的城镇化发展水平,用人均GDP表示经济发展,选取产业结构具体分析城镇化与经济发展的相互作用情况。用地理探测器模型分析新疆的城镇化与经济发展间的相互影响及两者之间的时空相互作用机制。结果发现:(1)新疆各地州(市)的城镇化发展差异大且城镇化整体发展速率缓慢。(2)地区间的产业结构布局不均衡。(3)新疆城镇化对经济增长的影响力表现为波动增长;各地区的作用力大小存在较大差异。(4)新疆城镇化发展对经济发展的作用强于经济发展对城镇化进程的作用。

submitted time 2020-11-24 From cooperative journals:《干旱区地理》 Hits32Downloads15 Comment 0

7. chinaXiv:202011.00113 [pdf]

中国366个城市空气污染综合程度的时空演变特征分析

刘清
Subjects: Geosciences >> Geography

采用2016—2017年中国366个城市1 484个监测站点的空气质量近地监测数据,以期最大程度覆盖西部地区,填补现状对西北热点地区污染因子探讨的空白。运用空间描述性统计、空间插值、空间自相关、标准差椭圆与重心分析方法,从年度、季度、月度、日度对比的角度探讨中国空气质量的污染类型、发展趋势、集聚与迁移特征。研究发现:基于插值法,可将全国分为3个区域,临海性与山地性对空气质量优良区产生显著的正响应。山西是污染加重程度最大的省份,主要受SO2浓度升高影响,而北京与河南是污染改善效果最明显的省份,主要是PM2.5的治理成效显著。空气质量分布格局以新疆西部和冀鲁豫形成双核高值聚类模式,并且集聚深受温度分带的影响。空气质量总体分布朝向呈东北—西南方向,转移重心均分布在河南省,以向东北方向移动为主,这种分布变迁又重新定义了其季节分异。全国主要的污染类型以PM10与PM2.5为主。PM10主要分布在新疆地区,受风沙过境扬尘污染自然因素更大,PM2.5主要分布在华中、华北、苏北地区,受人为经济活动影响更大。

submitted time 2020-11-24 From cooperative journals:《干旱区地理》 Hits28Downloads14 Comment 0

8. chinaXiv:202011.00115 [pdf]

近58 a新疆巴州极端气温事件变化特征

赵明玉
Subjects: Geosciences >> Geography

选取 WMO 推荐的 15 个极端气温指数,对 1959—2016 年新疆巴州地区 7 个气象站点观测的日最高、最低气温数据,采用一元线性回归法等多种统计方法对研究区极端气温事件进行分析。结果表明:近 58 a来新疆巴州地区冷暖指数变化呈非对称性,暖指数呈不同程度的显著上升,冷指数总体呈显著下降趋势,其中 TN90P年际变化率最大,为 4.67 d?(10 a)-1。夜指数(TN10P、TN90P)和昼指数(TX10P、TX90P)变化率前者大于后者。冷指数在 20 世纪 80 和 90 年代中后期发生突变,暖指数和GSL、WSDI[WTBZ]突变时间一致为 90 年代中后期,冷指数对气候变化较敏感。发生频率:极端高温增加,极端低温降低;强度:增强;持续时间:作物生长期呈显著增加趋势,其中巴音布鲁克增加显著,幅度最大〔4.4 d?(10 a)-1〕。TNx、TXx和GSL主周期均为 28 a。高载荷指数: TEMA(0.335),TN10P(-0.313)和TN90P(0.312),是影响该地区整体气温发生变化的主要因素。

submitted time 2020-11-24 From cooperative journals:《干旱区地理》 Hits31Downloads19 Comment 0

9. chinaXiv:202011.00116 [pdf]

黄土高原塬面保护区降雨侵蚀力时空分布特征及其影响因素研究

孙从建
Subjects: Geosciences >> Geography

通过采用Mann-Kendall趋势分析法、小波分析方法、地统计插值等方法,基于黄土高原塬面保护区及临近的21个站点的逐日降水量数据,对区域内降雨侵蚀力的时空变化,趋势及主要影响因素进行了分析。结果表明:(1) 黄土塬面保护区1960—2017年多年平均降雨量为599.2 mm;多年平均降雨侵蚀力为1 871.91 MJ?mm?hm-2?h-1?a-1,降雨侵蚀力在过去60 a来呈微弱上升趋势且变化的季节差异显著。(2) 黄土高原塬面保护区降雨侵蚀力的空间分布大体呈由南部向两侧递减的趋势,MannKendall [WTBX]Z[WTBZ]值除研究区北部、东部呈下降趋势,其余区域都为上升趋势。(3) 黄土高原塬面保护区降雨侵蚀力多年存在32 a的大周期,在大周期内还存在13 a、52 a的小周期。(4) 影响北半球中高纬度地区的主要的大气环流因子中仅Cold & Warm Episodes by Season因子的波动对整个区域和陕西塬区的降雨侵蚀力有一定影响,二者存在一定的负相关性,其余环流指数与降雨侵蚀力没有显著的关联性;此外太阳黑子与陕西塬区降水侵蚀力变化规律存在一定的正相关,与其他塬区并无显著关联性。

submitted time 2020-11-24 From cooperative journals:《干旱区地理》 Hits29Downloads15 Comment 0

10. chinaXiv:202011.00117 [pdf]

新疆雪灾的时空分布特征及其等级划分

王勇; 赵战成
Subjects: Geosciences >> Geography

利用新疆1954—2018年雪灾资料分析其灾害时空特征,时间上雪灾灾损强度在90年代后出现明显加大,2010年出现跃增特点,空间上雪灾灾损强度新疆西部多于东部,北部多于南部,山区多于盆地或平原。用雪灾出现次数、房屋倒塌间数、牲畜棚圈倒塌间数、损坏大棚数、死亡牲畜数、受灾面积、经济损失等多指标综合分析法来客观构建灾损指数,符合[Γ分布的灾损指数结合F分布函数能客观的描绘出雪灾等级,分为一般、较重、严重、特重4个等级。根据构建的雪灾等级,发现新疆雪灾特重灾区集中在天山山区及其以北地区,南疆仅有喀什地区为特重灾区。

submitted time 2020-11-24 From cooperative journals:《干旱区地理》 Hits31Downloads17 Comment 0

12345678910  Last  Go  [1429 Pages/ 14288 Totals]