转座子的起源及其和物种进化的关系

关于转座子的属性及其起源问题现在还没有解决,在这篇论文中,作者经过分析提出了转座子由病毒或逆转录病毒退化而来的观点,并且阐述了转座子与物种进化之间的关系,主要从转座子影响物种适应性和引起基因突变,染色体畸变两个方面进行了说明。     

核酸序列的模糊聚类与分子进化

将核酸序列(编码区)分成几类,求出每类的平均信息参数(D_L),用模糊聚类的方法研究它们的相似性和同源性,求出各级相似分岔值并导出动态聚类图.证明了短程相似分岔与序列进化有明显的相性,即L=2-5的一级相似分岔值与物种出现地质年代的对数保持较好的线性关系.     

发展方程Ut=aup的恒稳定的差分格式

对发展方程u_t=au_p(a是常数,u_p=■~pu/■x~p,P=1,2,…)引入稳定项,构造了一组新的带参数、相容且恒稳定的三层差分格式.其中P为偶数的格式(2.6)是显格式,是Du Fort—F■ankel格式的推广;P为奇数的格式(3.2),(3.3)及(3.4)是半显格式,可显式计算,(3.5)与(3.6)是隐格式,它们对应的线性方程组的系数矩阵为三对角线阵,可用追赶法求解.     

New structure model of oxygen-evolving center and mechanism for oxygen evolution in photosynthesis

So far, many important questions and problems concerning the structure and mechanism of photosynthetic oxygen evolution are still unsolved. On the basis of recent achievements in this field, a new structure model is proposed whereby two H2O molecules bind asymmetrically to two manganese ions (Mn1Ⅱ and Mn4Ⅲ) at the open end of "C" shaped cluster and keep rather large distance. Two histidine residues coordinate to the other two manganese ions in higher oxidation state (Mn2Ⅳ and Mn3Ⅳ ) through their nitrogen atoms of the imidazole. Cl bound as terminal ligand to Mn4Ⅲl is connected to Ca, and the latter is needed to maintain the special configuration of two Mn2O2 units by bridged-oxo and bridged-carboxylate ligands. The whole structure of oxygen evolution center is asymmetry. A new mechanism for oxygen evolution invokes predictions of asymmetric oxidation of two H2O molecules, dynamic structural changes of oxygen e-volving center and indirect proton transport, etc. Only in S2 state, could Mn1Ⅳ = O. intermediate with high oxidation potential be formed. The S2→S3 process occurs with significant structural changes, as well as intramolecular and intermolecular hydrogen transfer. The S3 state corresponds to intermediate of Mn1Ⅳ-O… H… O-Mn4Ⅳ . During S3→ [S4] →S0, the O-O bond is formed only in S4 state. The change of nucleophilic interaction between Cl and manganese ions different oxidation states has consequence for the significant structural changes in H2O oxidation process.     

法律教育的实效性研究——论学生法律思维的积淀与养成

学生法律思维的培养是提高学校法律教育实效的基础性环节。它可通过案例分析、模拟法庭训练、法律诊所等诸多方式来实现，进而提高法律教育的实效性。     

浙江金衢盆地八十年代气候变化趋势及灾害演变特征分析

本文分析了本世纪八十年代金衢盆地的气候变化趋势。与前三个年代（五十、六十、七十年代）比较，八十年代具有变冷，少光，洪涝灾害频繁的趋势特征。同时，春季“三寒”（倒春寒、种田寒、５月寒），晚春初夏异常高温危害，夏凉，冬暖等异常现象突出。着重分析了气候变化及灾害演变对农林环境的不利影响，讨论了九十年代气候变异趋势及其对策。     

综合进化论的发展现状

本文论述了综合进化论的形成和发展的几个主要阶段.着重介绍了综合进化论的发展现状和面临的挑战,并对其研究趋势进行了探讨.     

An in situ zircon Hf isotopic,U-Pb age and trace element study of banded granulite xenolith from Hannuoba basalt： Tracking the early evolution of the lower crust in the North China craton

Backscattered electron images, in situ Hf isotopes, U-Pb ages and trace elements of zircons in a banded granulite xenolith from Hannuoba basalt have been studied. The results show that the banded granulite is a sample derived from the early lower crust of the North China craton. It is difficult to explain the petrogenesis of the xenolith with a single process. Abundant information on several processes, however, is contained in the granulite. These processes in-clude the addition of mantle material, crustal remelting, metamorphic differentiation and the delamination of early lower crust. About 80% of zircons studied yield ages of 1842 ±40 Ma, except few ages of 3097-2824 Ma and 2489-2447 Ma. The zircons with ages older than 2447 Ma have high εHf (up to +18.3) and high Hf model age (2.5-2.6 Ga), indicating that the primitive materials of the granulite were derived mainly from a depleted mantle source in late Archean. Most εhf of the zircons with early Proterozoic U-Pb age vary around zero, but two have     

Possible developmental mechanisms underlying the origin of the crown lineages of arthropods

The extraordinarily preserved, diverse arthropod fauna from the Lower Cambrian Maotianshan shale, central Yunnan (southwest China), represents different evolutionary stages stepping from stem lineages towards crown arthropods (also called euarthropods), which makes this fauna extremely significant for discussion of the origin and early diversification of the arthropods. Anatomical analyses of the Maotianshan shale arthropods strongly indicate that