A local positive feedback of the tropical Pacific ocean-atmosphere system on interdecadal timescales

SINCE THE 1990S, THE CLIMATIC VARIABILITY ON INTERDE- CADAL TIME SCALES BECAME THE FOCUS OF THE INTERNATIONAL CLIMATOLOGY RESEARCH MISSIONS[1―3]. ON TIME SCALES OF A DECADE OR MORE, THE OCEAN CIRCULATION PREDOMINATEDHEAT BALANCE AND HYDROLOGICAL CYCLE, S…     

Sr-Nd isotope geochemistry of eolian dust of the arid-semiarid areas in China： Implications for loess provenance and monsoon evolution

Strontium (Sr) is a divalent alkaline earth element. Its ionic radius (0.113 nm) is slightly larger than that of calcium (0.099 nm), and Sr thus substitutes isomor- phously for Ca in many minerals. Neodymium (Nd) is a rare earth element. Its chemical prop…     

Temporal-spatial dynamics of distribution patterns of microorganism relating to biological soil crusts in the Gurbantunggut Desert

Biological soil crusts serve as an important biological factor contributing to the sand fixation. This study was conducted to investigate the temporal-spatial variability of microorganism in crusts relating to locations, soil layers of sand dunes and seasons. At moss-dominated inter-dune areas, higher soil nutrient and water concentrations were likely to maintain the microbial activities. Bacteria showed the highest capabilities of settlement and growth in inter-dunes in both spring and autumn. Soil water content reached the highest value in soil crusts in the inter-dune areas, especially in spring. Variations of quantities of actinomyces and fungi basically showed the consistent trend in different locations of sand dunes. With the deepening of soil layers, vertical distribution of quantities of each microorganism group showed different characteristics because environmental factors fluctuated in both spring and autumn. Among different microorganism groups, bacteria were predominant, actinomyces the next and fungi the least in both spring and autumn in all soil layers （0-20 cm）. The proportion of bacteria and soil water content were higher in spring than those in autumn in all soil layers （0-20 cm）. No consistent trends were found in actinomyces and fungi. The results showed that the quantities of microorganisms were significantly positive correlated with organic matter content, soil water content, total N, total P, available P, available K, pH, electrical conductivity, total salt content,catalase, urease, phosphatase and alkaline phosphatase.     

Response of downstream sediment to water resource development in mainstream of the Lancang River

The impact of hydropower cascades of the Lancang River on downstream sedimentation has become one of the key problems in the research of the transboundary water resource development and its possible environmental effects. In this paper, the newest sediment data series spanning 17 years （1987-2003） at Yunjinghong hydrometric station and Chiang Saen hydrometric station, in northern Thailand, are analyzed to reveal these effects. Monthly mean sediment concentration data of the two stations are compared in-phase and yearly series are analyzed by the method of correlation and regression analysis and causality test. The analysis result shows that, though both of them are located at lower reaches of Manwan and Dachaoshan hydropower stations which are already constructed and in use, the sediment responses of the two stations are different under the regulation of the hydropower stations Annual series at Yunjinghong station are positively correlated but do not match well with those at Chiang Saen station. In addition, the results of Granger causality test on the time series also suggest that the series of maximum monthly mean sediment concentration of the Yunjinghong station each year may give cause for the ones of Chiang Saen station, while the series of minimum monthly mean sediment concentration each year and annual mean sediment concentration of Yunjinghong do not evidently give cause for the ones of the other station. Undoubtedly, this discovery will provide new evidences to assess the impacts of cascades construction in mainstream of the Lancang River on the variation of downstream sediment and its transboundary effects.     

极大η-单调映象的广义隐拟变分包含

作者引入了Hilbert空间中一类关于极大η-单调映象的广义隐拟变分包含,并利用预解算子技术建立了这类变分包含解的迭代算法逼近,证明了其解的存在性以及由算法生成的迭代序列的收敛性.     

交换C~*-代数张量积的纯态和谱

讨论了非交换C*-代数的谱与纯态值域,得到了C*-代数张量积中两个元的本质纯态值域的表示.     

一类基于二部图的（g，f）-2-覆盖图的研究

一个图G称（g,f）-2-覆盖图，如G的任何两条边都属于它的一个（g,f）-因子．本文得到了如下结论：（i）当g≤f时一个二部图是（g,f）-2-覆盖图的一个充分必要条件；（ii）当f（x）=f（Y）时一个二部图是f-2-覆盖图的一个充分必要条件．     

双枝模糊集并-表现定理

建立了双枝模糊集并-表现定理，讨论了双枝模糊集的运算性质.结果表明：双枝模糊集表现定理是单枝模糊集表现定理的一般形式，单枝模糊集表现定理是双枝模糊集表现定理的特例.     

二分图上有限制条件的(g,f) 因子和f 因子

设图G=(X,Y,E)是二分图, g,f是定义在V(G)上的正整值函数, 且对任意的x∈V(G)有g(x)＜f(x), 证明了: 如果图G是(mg,mf-1)-图, M是G的任一含有m条边的对集, 则存在图G的一个(g,f)-因子F, 使F包含M任意给定的一条边, 并且不包含其他的m-1条边; 二分图G是(2m-1)-边连通的(mf)-图, 则图G有一个f-因子包含任意给定的一条边, 并且不包含任意其他的m-1条边.     

反相高效液相色谱法同时分离和测定多种头孢菌素

建立了同时分离测定6种临床最常用的头孢菌素(头孢他啶、头孢拉定、头孢氨苄、头孢哌酮、头孢唑林、头孢噻肟)的高效液相色谱法.采用SHIM-PACK VP-ODS(150×4.6 mmI.D.)色谱柱,以乙腈及0.05 mol.L-1HAC-NaAC缓冲溶液(pH=4.0)组成流动相梯度淋洗,254 nm紫外检测,在15 min内分离并测定了上述6种头孢菌素.6种药物最低检出限均可达到0.20μg.mL-1.将该法用于尿样中药物含量的测定取得了满意结果.6种药物在尿样中回收率为92.4%~96.1%.实验证明该方法操作简便、快速灵敏、准确.