流域水污染治理模式创新研究

我国严峻的流域水污染已成为可持续发展的严重威胁,而目前的流域水污染治理模式却难以有效地解决这一难题.针对流域水污染防治的管理体制、机制、政策体系所存在问题,提出了创新流域水污染治理模式的对策与方法.     

浅析公路桥梁建设的现状及安全对策

随着社会经济快速发展,公路也在高速发展,但在公路桥梁建设中存在不少问题.文章就公路桥梁建设中存在的问题进行深入浅出的分析,从而阐述了在建设中的安全对策.     

耗散KDV型方程的渐近吸引子

摘 要:本文考虑了耗散KDV型方程 的渐近吸引子,即构造了一个有限维解序列.首先利用数学归纳法证明了该解序列不会远离方程的整体吸引子；其次，证明了它在长时间后无限趋于方程的整体吸引子, 并且给出了渐近吸引子的维数估计.     

Chiral pyrrolidine-azole conjugates: Simple and efficient asymmetric organocatalysts for Michael addition to nitrostyrenes

Simple pyrrolidine-azole conjugates have been synthesized and found to be efficient catalysts for asymmetric Michael addition to nitrostyrenes. The identified optimal catalysts, pyrrolidine-azoles 2, 8 and 13, could catalyze the asymmetric Michael addition of a range of Michael donors and nitrostyrenes in high yields (up to 99%) and excellent stereoselectivities (up to 99:1 dr and 97% ee).     

弹性碰撞的图示分析法

通过引入牵连动量和相对动量等物理量,用图示分析法研究了弹性碰撞.研究结果表明,该方法可以形象而直观地描述弹性碰撞的过程和结果,对弹性碰撞的理论研究和实际应用都有重要的意义.     

Sinorhizobium meliloti lsrB is involved in alfalfa root nodule development and nitrogen-fixing bacteroid differentiation

Rhizobia interact with host legumes to induce the formation of nitrogen-fixing nodules, which is very important in agriculture and ecology. The development of nitrogen-fixing nodules is stringently regulated by host plants and rhizobial symbionts. In our previous work, a new Sinorhizobium meliloti LysR regulator gene (lsrB) was identified to be essential for alfalfa nodulation. However, how this gene is involved in alfalfa nodulation was not yet understood. Here, we found that this gene was associated with prevention of premature nodule senescence and abortive bacteroid formation. Heterogeneous deficient alfalfa root nodules were induced by the in-frame deletion mutant of lsrB (lsrB1-2), which was similar to the plasmid-insertion mutant, lsrB1. Irregular senescence zones earlier appeared in these nodules where bacteroid differentiation was blocked at different stages from microscopy observations. Interestingly, oxidative bursts were observed in these nodules by DAB staining. The decreased expression of lipopolysaccharide core genes (lpsCDE) was correspondingly determined in these nodules. S. meliloti lipopolysaccharide is required for suppression of oxidative bursts or host cell defense. These findings demonstrate that the S. meliloti lsrB gene is involved in alfalfa root nodule development and bacteroid differentiation by suppressing oxidative bursts or defense responses in host cells.     

Optimal portfolio selection strategies under some constraints

A portfolio selection problem for any utility function is introduced, where all the market coefficients are random and the wealth process under any admissible trading strategy is not allowed to be below a benchmark wealth process. The problem is completely solved using a decomposition approach. First, the portfolio selection problem is formulated, and its feasibility is characterized. Then, the problem is decomposed to two steps to solve. After a system of equations for a Lagrange multiplier is solved, the portfolio selection problem is derived as the replicating portfolios of contingent claims. Finally, some simulations are demonstrated. Biography: LUO Kui(1981–), female, Ph. D. candidate, research direction: financial mathematics.     

高等成人教育的革新之路——基于信息技术的现代远程教育

在信息化社会，知识经济时代即将到来之际，成人教育面临着诸多亟需解决的问题．如何利用信息技术和Internet的优势，发展现代远程教育将是成人教育革新发展的主要的途径之一．     

海泡石表面改性及其对橡胶性能补强的研究

通过对海泡石进行表面处理，探讨海泡石表面改性的最佳条件，研究了表面处理剂的种类，用量及表面处理时间及干燥温度等因素对性能的影响，结果表明，海泡石在填充橡胶综合性能指标上明显优于陶土和碳酸钙填充的橡胶，可替代作为一种新型橡胶无机填料，用于橡胶的补强，同时可简化生产工艺，降低生产成本。     

关于内部收益率与现金流量模式关系的分析

研究了内部收益率与现金流量模式的关系。 通过对折现率与现金流量结构间的相互关系的分析，探讨内部收益率的存在性与现金流量模式的关系，给出净现值法与内部收益率法具有一致性的条件；在定义修正内部收益率的基础上，给出其计算公式，并将内部收益率法的应用范围推广。