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51.
青藏高原唐古拉山冬克玛底河流域水文过程特征分析 总被引:16,自引:16,他引:16
利用1993年5 ̄9月连续时间序列的资料,对青藏高原唐古拉山冬克玛底冰川区及其流域的水文过程特征进行初步分析。由于青藏高原季风环流的影响,在性质不同气团控制所产生的降水天然过程的降水量差别极大,该区域主要降水集中在6 ̄8月,Tretyakov雨量器对标准雨量器捕捉率的修正量小于天山地区的研究结果,该流域地面蒸发过程较为强盛,各种下垫面的蒸发量占流域水量平衡收入的37%,土壤蒸发量与水面蒸发和土壤含 相似文献
52.
黄河上游径流预报的灰色拓扑方法 总被引:5,自引:6,他引:5
以龙羊峡水库年平均入库流量预报为例,根据灰色系统理论的建模方法,利用龙羊峡水库入库水量代表站唐乃亥水文站的实测径流资料,建立了一个GM(1,1)拓扑预测模型,用于黄河上游径流的长期预报,并取得了较为满意的结果。 相似文献
53.
从宏观和微观两方面对不同变质程度煤所形成焦炭的结构、构造进行了深入研究。从气煤到肥煤阶段(Ro,m:0.77%~1.16%),焦炭气孔壁厚度逐渐增大;进入焦煤阶段(Ro,m>1.16%),焦炭气孔壁厚度降低。气煤、13焦煤形成的焦炭结构以各向同性体为主,焦煤、肥煤炼出的焦炭以粒状镶嵌结构为主。由气煤和高变质程度的焦煤形成的焦炭,其气孔以微孔和大孔为主,气孔分布标准差Ds最大;肥煤炼出的焦炭,其气孔分布大小较均一;13焦煤和低变质程度的焦煤成焦后,气孔分布状况介于上述二者之间 相似文献
54.
为探讨煤的显微组分的结焦性,对不同变质程度煤的镜质组、壳质组和惰性组分别进行了显微镜热台加热试验.在加热过程中,活性组分经历了3个明显不同的变化阶段,即变形阶段、胶质体形成阶段以及固化阶段.随煤变质程度的增加,镜质组的初变温度和胶质体形成时的温度逐渐增大,而固结温度变化规律不明显;壳质组在低变质阶段因受热而挥发掉,但随煤级增高其变形程度减弱;半镜质组在受热过程中也有变形和少量胶质体形成,而惰性组只发生微弱变化.在低变质阶段,活性显微组分形成的焦炭显微结构以各向同性为主;随变质程度的增高,焦炭显微结构中各向异性成分比例增大 相似文献
55.
催化褪色光度法测定痕量锰的研究及应用 总被引:2,自引:0,他引:2
本研究了在PH=4.0醋酸-醋酸钠缓冲溶液中,锰催化KIO4氧化5-Br-PADAP的褪色反应及其动力学条件,建立了一个痕量锰的高灵敏度新方法,方法灵敏度为1.32×10^-10g/ml,测定范围Mn^2+浓度为0 ̄1.5μg/ml,用于测定人发,自来水,茶叶中痕量锰,结果满意。 相似文献
56.
对板块说应持分析态度,既充分肯定它的创见,又要看到其不足。张文佑倡导的断块说强调地质演化中的陆洋地壳转化,即拉张造洋、挤压造陆。近年来提出的开合说,继承了板块说、断块说和新地槽-地台说的合理内核。笔者认为,断块-开合大地构造说是中国大地构造研究中有代表性的思潮。本文概括了其基本观点,强调了开合中的多模式、多旋回和非封闭性、不可逆性。 相似文献
57.
Jianwei Wang 《Earth and Planetary Science Letters》2004,222(2):517-527
Molecular dynamics (MD) modeling of the 10-Å phase, Mg3Si4O10(OH)2·xH2O, with x=2/3, 1.0 and 2.0 shows complex structural changes with pressure, temperature and water content and provides new insight into the structures and stabilization of these phases under subduction zone conditions. The structure(s) of this phase and its role as a reservoir of water in the mantle have been controversial, and these calculations provide specific predictions that can be tested by in situ diffraction studies. At ambient conditions, the computed structures of talc (x=0) and the 10-Å phases with x=2/3 and 1.0 are stable over the 350-ps period of the MD simulations. Under these conditions, the 10-Å phases show phlogopite-like layer stacking in good agreement with previously published structures based on powder X-ray diffraction data for samples quenched from high-pressure and high-temperature experiments. The calculations show that the 10-Å phase with x=2.0 is unstable at ambient conditions. The computed structures at P=5.5 GPa and T=750 K, well within the known stability field of the 10-Å phase, change significantly with water content, reflecting changing H-bonding configurations. For x=2/3, the layer stacking is talc-like, and for x=1.0, it is phlogopite-like. The calculations show that transformation between these two stackings occurs readily, and that the talc-like stacking for the x=2/3 composition is unlikely to be quenchable to ambient conditions. For x=2.0, the layer stacking at P=5.5 GPa and T=750 K is different than any previously proposed structure for a 10-Å phase. In this structure, the neighboring basal oxygens of adjacent magnesium silicate layers are displaced by b/3 (about 3 Å) resulting in the Si atoms of one siloxane sheet being located above the center of the six-member ring across the interlayer. The water molecules are located 1.2 Å above the center of all six-member rings and accept H-bonds from the OH groups located below the rings. The b/3-displaced structure does not readily transform to either the talc-like or phlogopite-like structure, because neither of these stackings can accommodate two water molecules per formula unit. There is likely to be a compositional discontinuity and phase transition between the b/3-displaced phase and the phase with phlogopite-like stacking. The simulations reported here are the first to use the recently developed CLAYFF force field to calculate mineral structures at elevated pressures and temperatures. 相似文献
58.
59.
SHA Liqing ZHENG Zheng TANG Jianwei Wang Yinghong ZHANG Yiping CAO Min WANG Rui Liu Guangren WANG Yuesi SUN Yang 《中国科学D辑(英文版)》2005,48(Z1)
With the static opaque chamber and gas chromatography technique, from January 2003 to January 2004 soil respiration was investigated in a tropical seasonal rain forest in Xishuangbanna, SW China. In this study three treatments were applied, each with three replicates: A (bare soil), B (soil+litter), and C (soil+litter+seedling). The results showed that soil respiration varied seasonally, low from December 2003 to February 2004, and high from June to July 2004. The annual average values of CO2 efflux from soil respiration differed among the treatments at 1% level, with the rank of C (14642 mgCO2· m-2. h-1)>B (12807 mgCO2· m-2. h-1)>A (9532 mgCO2· m-2. h-1). Diurnal variation in soil respiration was not apparent due to little diurnal temperate change in Xishuangbanna. There was a parabola relationship between soil respiration and soil moisture at 1% level. Soil respiration rates were higher when soil moisture ranged from 35% to 45%. There was an exponential relationship between soil respiration and soil temperature (at a depth of 5cm in mineral soil) at 1% level. The calculated Q1o values in this study,ranging from 2.03 to 2.36, were very near to those of tropical soil reported. The CO2 efflux in 2003was 5.34 kgCO2· m-2. a-1 from soil plus litter plus seedling, of them 3.48 kgCO2· m-2. a-1 from soil (accounting for 62.5%), 1.19 kgCO2· m-2. a-1 from litter (22.3%) and 0.67 kgCO2·m-2. a-1 from seedling (12.5%). 相似文献
60.