景观异质性与生物多样性关系探讨

生物多样性是人类生存和发展的基础，它决定着景观生态系统的稳定性和复杂性。景观异质性是生物多样性的前提，景观异质性有利于促进景观生态系统的能量流动和物质循环，减小扰动的传播，并是生态系统生物共生的基础。干扰影响景观异质性及生物多样性，人为的干扰使景观破碎严重，直接影响生物多样性保护，自然景观的科学管理是保护生物多样性的核心与保证。     

589nm可调谐法拉第反常色散滤光器特性分析

考虑到钠原子Ｄ２线（３Ｓ１／２→３Ｐ３／２）５８９ｎｍ的超精细结构，以及具有Ｖｏｉｇｔ线型的左右旋园偏振谱线的贡献，我们对钠原子气体的法拉第反常色散滤光器的透过率、中心频率移动、通频带宽等跟外加纵向磁场强度、原子汽室温度的关系进行了理论分析．结果表明：该滤光器的中心工作频率磁场调谐能力约为８０ＧＨｚ／Ｔ，通频带宽为０．００１～０．０１ｎｍ，透过率约可达１００％．     

双线纵向激励F^＋2型色心激光器的激励尺寸效应

探讨了双线纵向激励Ｆ＾＋２型色心激光器在不同泵浦光，辅助光和振荡光的束腰半径之经下的增益特性。研究表明，为获得较高基模比例的激光输出和较高的泵浦光利用效率，泵浦光的束腰半径应选择略小于振荡的束腰半径，辅助光的束腰半径应泵浦光的束腰半径近似相等。     

纳米硅薄膜中量子点的库仑阻塞效应

用纳米硅薄膜制成了共振隧穿量子点二极管，在77K温度下对其I－V特性进行了测量，得到了具有共振隧穿特征的实验结果。对实验结果分析表明，纳米尺寸晶粒构成的量子点具有库仑阻塞效应。     

pH effect of· OH radical induced oxidation of phosphoryl- methionine in aqueous solution

Conclusion The results of pulse radiolytical research on the · OH radical-induced oxidation of NDM in aqueous solution demonstrate that pH value has a great influence on the radiolytical mechanism of NDM. At low pH value, the product is mainly stabilization of the oxidizing sulfur centre in the three-electron-bonded cation radical NDM₂ ·⁺ [S]; with the increase of pH value, NDM₂ ·⁺ [S] gradually decays to become the reducing α-amino radical which was verified by the chemical method and whose yield was also calculated. Compared with Met₂ ·⁺ [S] produced by the · OH radical-induced oxidation in aqueous solution [1], the stability of NDM₂·⁺ [S] increases and the yield of α-amino radical decreases. This suggests that the introduction of phosphoryl group has a coordinating effect on the radioprotection of methionine to biological systems, and provides the essentially theoretical foundation for the thorough clarification of the reversible phosphorylation of proteins.     

The strong cooperativity of dioxygen binding by dicobalt (II) diporphyrin compounds in nonaqueous solution at room temperature

Thermodynamic data were determined for the reversible binding of O₂ to two compounds of dicobalt(II) di(meso-tetra-phenyl)porphyrin derivatives with different lengths of diamidoaliphatic bridge (abbreviated to Co₂PP₈ and Co₂PP₄) in N,N-dimethylformamide at room temperature. The partial pressure of dioxygen necessary for half-oxygenation (P _1/2) and hill coefficient (n) at 298 K were determined as follows:P _1/2=54.2 kPa,n=2.0 for Co₂PP₈ andP _1/2=6.8 kPa,n=1.8 for Co₂PP₄, respectively. The rate equations of reversible oxygen binding by Co₂PP₈ were determined and the reaction path was proposed. The results of ther-modynamic and kinetic studies indicate that there exists strong cooperative effect during oxygenation of the compounds. The ESR observation reveals that the dioxygen complexes formed in the solutions are of superoxo (Co-O ₂ ⁻ ) type. Supported by the Research Foundation of the State Education Commission of China Zhou Xiaohai: born in 1962, Ph.D. Associate professor     

热流模型半导体方程组的光滑解

考虑具热效应的半导体方程组的初边值问题，应用Ｓｃｈａｕｄｅｒ不动点原理和先验估计方法，证明了该问题整体光滑解的存在唯一性。