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	High-frequency East Asia monsoon variability during 115000-93000 a BP in Northern China 期刊论文 OAI收割 TERRESTRIAL ATMOSPHERIC AND OCEANIC SCIENCES, 2021, 卷号: 32, 期号: 2, 页码: 159-169 作者: Wang, Fengnian; Si, Yuejun; Li, Baosheng; Niu, Dongfeng; Wen, Xiaohao \| 收藏 \| 浏览/下载：37/0 \| 提交时间：2021/12/06 Aeolian sediments Trace geochemical element Monsoonal climate changes MIS5c-d period Mu Us Desert
	An underlying clock in the extreme flip-flop state transitions of the black hole transient Swift J1658.2-4242 期刊论文 OAI收割 Astronomy and Astrophysics, 2020, 卷号: 641, 页码: A101 作者: HXMT \| 收藏 \| 浏览/下载：58/0 \| 提交时间：2022/02/08 accretion accretion disks black hole physics X-rays: binaries time Astrophysics - High Energy Astrophysical Phenomena Abstract: Aims: Flip-flops are top-hat-like X-ray flux variations, which have been observed in some transient accreting black hole binary systems, and feature simultaneous changes in the spectral hardness and the power density spectrum (PDS). They occur at a crucial time in the evolution of these systems, when the accretion disc emission starts to dominate over coronal emission. Flip-flops remain a poorly understood phenomenon, so we aim to thoroughly investigate them in a system featuring several such transitions. Methods: Within the multitude of observations of Swift J1658.2-4242 during its outburst in early 2018, we detected 15 flip-flops, enabling a detailed analysis of their individual properties and the differences between them. We present observations by XMM-Newton, NuSTAR, Astrosat, Swift, Insight-HXMT, INTEGRAL, and ATCA. We analysed their light curves, searched for periodicities, computed their PDSs, and fitted their X-ray spectra, to investigate the source behaviour during flip-flop transitions and how the interval featuring flip-flops differs from the rest of the outburst. Results: The flip-flops of Swift J1658.2-4242 are of an extreme variety, exhibiting flux differences of up to 77% within 100 s, which is much larger than what has been seen previously. We observed radical changes in the PDS simultaneous with the sharp flux variations, featuring transitions between the quasi-periodic oscillation types C and A, which have never been observed before. Changes in the PDS are delayed, but more rapid than changes in the light curve. Flip-flops occur in two intervals within the outburst, separated by about two weeks in which these phenomena were not seen. Transitions between the two flip-flop states occurred at random integer multiples of a fundamental period of 2.761 ks in the first interval and 2.61 ks in the second. Spectral analysis reveals the high and low flux flip-flop states to be very similar, but distinct from intervals lacking flip-flops. A change of the inner temperature of the accretion disc is responsible for most of the flux difference in the flip-flops. We also highlight the importance of correcting for the influence of the dust scattering halo on the X-ray spectra.
	烟台牟平海洋牧场季节性低氧对大型底栖动物群落的生态效应期刊论文 OAI收割生物多样性, 2019, 卷号: 27, 期号: 2, 页码: 200-210 作者: 李宝泉 \| 收藏 \| 浏览/下载：21/0 \| 提交时间：2020/06/17 低氧群落结构群落恢复敏感种机会种 hypoxia community structure community recovery sensitive species opportunistic species Hypoxia is a common phenomenon in the world's oceans, especially in the shallow waters of coastal zones. Rates of hypoxia are increasing due to global climatic changes and anthropogenic activities. Hypoxia can cause mass mortality of marine animals and can have severe negative impacts on marine ecosystems. To better understand the effects of hypoxia on macrobenthic communities, a survey was carried out in the Muping Marine Ranch (Yantai) during June, August and September of 2016. Results showed that seasonal hypoxia led to changes in benthic community structure, especially in terms of species composition and dominant species. The dominant species were Polychaeta Lumbrinereis latreilli, Sternaspis scutata and Mollusca Endopleura lubrica in summer. The opportunistic species Lumbrinereis latreilli increased, whereas, sensitive species such as Leptomya minuta, Glycera chirori, Upogebia major, Pontocrates altamarimus, Eriopisella sechellensis decreased during the hypoxic period of August. Hypoxia also reduced biodiversity indices. The effect of hypoxia on abundance and biomass were not significant, mainly because of the increase in the opportunistic Lumbrinereis latreilli, which counteracted the decline in abundance and biomass of other species. Individual physiological tolerance to hypoxia was different among species. Lumbrinereis latreilli showed higher tolerance to hypoxia in dissolved oxygen (DO) = 1.0 mg/L compared to other species. Some sensitive species, such as Leptomya minuta, Upogebia major, Pontocrates altamarimus and Eriopisella sechellensis showed lower tolerance when DO < 2.5 mg/L. When DO increased to 2.5 mg/L, the macrobenthic community start to recover gradually. The recovery extent and time needed were closely related to the degree of seasonal hypoxia.
	Asteroseismology of the Double-mode High-amplitude delta Scuti Star VX Hydrae 期刊论文 OAI收割 ASTROPHYSICAL JOURNAL, 2018, 卷号: 861, 期号: 2, 页码: 96 作者: Yan, HL; Xue, HF; Fu, JN; Fox-Machado, L; Shi, JR \| 收藏 \| 浏览/下载：80/0 \| 提交时间：2018/12/27 EQUATION-OF-STATE STELLAR EVOLUTION PERIOD CHANGES PULSATION OPACITIES
	Land use dynamics and landscape change pattern in Hetao irrigation district, Inner Mongolia, China 会议论文 OAI收割 6th International Symposium on Digital Earth: Data Processing and Applications, Beijing, China, September 9, 2009 - September 12,2009 Zhang, Yinhui; Luo, Yi; Zhao, Wenwu 收藏 \| 浏览/下载：27/0 \| 提交时间：2014/12/07 This study analyzed spatial and temporal changes in land use in an irrigation district covering an area of 1.7 million ha in Northern China by GIS analyses and also investigated changes in landscape pattern using the landscape structure analysis program FRAGSTATS over the study period from 1986 to 2000. The decreases in farmland and the increases in grassland area mainly resulted from the policy of grain for green and converting slope farmland into pasture from China government. In spite of the efforts to conserve the fragile ecosystem the land degradation including soil salinization and grassland degradation was spreading rapidly. The area of alkali-saline land increased by 22493 ha and about 50555 ha of dense grassland degraded into mid-density grassland. In terms of landscape fragmentation both farmland and dense grassland showed the tendency of increased fragmentation. Both adverse natural conditions and human activities are responsible for the land degradation expansion in Hetao irrigation district but the root causes are increasing population pressure and irrational human activities such as flooding irrigation method and over-grazing. To prevent land degradation from spreading population control and improvement of the management are prerequisite approaches. 2010 SPIE.