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351.
Waste beer yeast was modified by pyromellitic dianhydride to improve its adsorption capacity for rhodamine B (RhB). Results showed that the adsorption capacity of the modified biomass for RhB was 600 mg g?1, which was about five times than that obtained on the unmodified biomass. Dye loaded modified biomass was regenerated by (1) a common eluent: HNO3 solution and (2) a self‐cleaning eluent: TiO2 hydrosol, while the pH of both systems varied from 1 to 4. Desorption experimental results showed that low desorption rates were obtained in both systems after the first desorption cycle. A large volume of HNO3 solution was needed to obtain high desorption rate, and a concentrated solution of RhB was left, which brought a secondary pollution. As a self‐cleaning eluent, acid TiO2 hydrosol acted both as eluent and photocatalyst. The desorbed RhB could be photodegraded under sunlight irradiation and the same hydrosol could be used in the next desorption cycle without losing its activity, which could economize large volumes of solvent. The results showed an adsorption capacity of the regenerated biosorbent for RhB of 450 mg g?1 by using hydrosol with pH 2 as eluent after four desorption/photodegradation cycles. 相似文献
352.
Earthquake characteristics and building damage in high-intensity areas of Wenchuan earthquake II: Dujiangyan and Pengzhou City 总被引:1,自引:0,他引:1
On May 12, 2008, a massive earthquake occurred along the Longmen Mountain Central Fault in Sichuan Province, China, causing serious damages to buildings near the fault. As the Longmen Mountain Central Fault and the Anterior Fault both traversed Dujiangyan and Pengzhou cities, the seismic intensity in these areas reached levels IX?CXI. Therefore, these two cities were among the most seriously damaged regions. In this article, the types of damage to buildings in the two cities and their affiliated towns or villages are investigated and reported. It is found that the damage to a building is related to its structure type, distance from the faults, and so on. The results provide valuable information on the seismic resistance of buildings in similar areas. 相似文献
353.
东亚沙尘源区晴空和云上沙尘气溶胶特征 总被引:4,自引:4,他引:0
利用2006年6月至2012年12月的CALIPSO Level 2 VFM产品、5 km分辨率的Aerosol Profile、Cloud Layer产品以及MISR反演的产品,揭示了东亚地区不同高度层上沙尘的时空分布特征,重点对比分析了东亚沙尘源区晴空和云上沙尘的垂直分布特征、消光系数和光学厚度。结果表明:塔克拉玛干沙漠和戈壁沙漠是东亚沙尘的主要源区,沙尘出现频率具有显著的季节差异,春季最多,夏秋相当,冬季最少,无论在晴空还是有云条件下,前者出现频率大于后者。对于同一地区而言,云上沙尘出现的最大高度较晴空沙尘更高。塔克拉玛干沙漠云上沙尘消光系数高值区集中在2~4 km,而戈壁沙漠则集中在3~5 km,但是在云层之上晴空和云上沙尘消光系数差别不大。塔克拉玛干沙漠以沙尘气溶胶为主,约占总气溶胶光学厚度的77%,晴空和云上沙尘光学厚度平均值分别为0.22和0.15;戈壁沙尘气溶胶约占总气溶胶光学厚度的52%,晴空和云上沙尘光学厚度的平均值分别为0.09和0.06。 相似文献
354.
Nguyen Thanh Son Chi Farn Chen Cheng Ru Chen Mario Giovanni Molina Masferrer 《国际地球制图》2013,28(12):1363-1383
AbstractThis study aims to develop an approach to characterize cropland drought conditions in El Salvador, Central America. The data were processed for 2016–2017 through three main steps: (1) reconstructing MODIS land-surface temperature (LST), (2) Landsat-MODIS data fusion and (3) drought delineation using the temperature vegetation dryness index (TVDI). The results of LST reconstruction using the random forests (RF) indicated the median RMSE value of 0.5?°C. The fusion results achieved from the STARFM compared with the reference Landsat data revealed close agreement with the correlation coefficient (r) values higher than 0.84. The TVDI results verified with that from the reference Landsat data indicated r values of 0.85 and 0.75 for 2016 and 2017, respectively. The larger very dry area was observed for the 2016 primera season due to prolonged droughts. Approximately 11.5% and 10.7% of croplands were, respectively, associated with very dry moisture condition in the 2016 and 2017 primera seasons. 相似文献
355.
356.
Large-scale coronal structures (helmet streamers) observed in the white-light corona during total solar eclipses and/or with
ground-based coronagraphs are mostly located only above quiescent types of prominences. These helmet streamers are maintained
due to the magnetic fields of the Sun. Time–latitudinal distribution of prominences during a solar cycle, however, shows both
the poleward and equatorward migrations, similar to the 530.3 nm emission corona (the green corona) intensities. Distribution
of observed coronal helmet streamers during total solar eclipses, enlarged with the helmet streamers as were obtained by the
ground-based coronagraph observations, are compared with the heliographic distribution of prominences and the green corona
intensities for the first time. It is shown that the distribution of above-mentioned helmet streamers, reflects – roughly
– the time–latitudinal distribution of prominences and emission corona branches, and migrates together with them over a solar
cycle. 相似文献
357.
杨茹 《成都信息工程学院学报》2002,17(3):227-230
英语中有大量的成语谚语,语言简练,寓意深刻。着重探讨在大学英语课堂中进行英语成语谚语教学的必要性及途径,以推进大学英语课程的教学改革。 相似文献
358.
Time-latitudinal distributions of the solar-surface magnetic fields and the green corona (530.3 nm, Fe XIV) intensities in
the period 1975 – 2004 are analyzed. Meridional migration maps show that time-varying components consist of both the poleward
and equatorward belts over a solar cycle. The green-corona maps are, for the first time, directly compared with magnetic flux
charts, yielding a good association between the green corona and magnetic fields; this is most reliably seen at high latitudes. 相似文献
359.
基于CloudSat-CALIPSO(CloudSat-Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observations)卫星反演资料以及ERA5(ECMWF Reanalysis v5)月平均再分析资料,分析了北极地区总云量及其出现频率最高的层积云(Sc)的时空分布特征,并且探讨了层积云形成的可能原因。分析结果表明:秋季是北极地区全年总云量最多的季节,且喀拉海—楚科奇海区域云量增加幅度较为明显,其中海气温差较大、表面潜热通量致使边界层上升运动较强且相对湿度大是该区域云形成和维持的主要因素。另外,北极地区分布着大量Sc,主要位于常年几乎无海冰覆盖的挪威海—巴伦支海区域。此区域的低层稳定度与Sc云量呈负相关,即低层稳定度越大,Sc云量越少,此现象与热带以及中纬度等地区不同。开阔的海洋表面通过地表—大气耦合、热量和湿度的湍流表面通量降低了低层稳定度,促进了层积云的形成,增加了层积云的覆盖。 相似文献
360.
桩靴接触应力是影响插桩深度的主要因素之一,桩靴的锥尖型式可能会影响接触应力的大小及分布。以江苏省启东市某插桩试验项目为例,针对不同的桩靴端部型式基于桩靴接触应力现场实测数据,分别采用国内外规范方法及数值计算方法对插桩深度开展预测分析,揭示桩靴端部型式对插桩深度的影响规律。结果表明:在插桩过程中不同锥端类型桩靴的接触应力呈现出中央大周边小的分布特征,表明现场桩靴为柔性结构类型;采用不考虑桩靴端部形状的规范方法进行桩靴插深预测,得出的预测结果同现场实测结果基本吻合;采用小变形有限元数值方法进行插深预测也可以得出令人满意的结果,研究结果可为类似工程实践提供参考。 相似文献