Properties of the pi h(9/2)circle times nu i(13/2) oblate band in Tl-188

High spin states in Tl-188 have been investigated via the Gd-157(Cl-35,4n) reaction at beam energy of 170 MeV. A rotational band built on the pi h(9/2) circle times nu(13/2) configuration with oblate deformation has been established. Considering the similarity between the band structure observed in odd-odd Tl nuclei, spin values have been tentatively proposed for the new band in Tl-188. The pi h(9/2) circle times nu(13/2) oblate band in Tl-188 shows low-spin signature inversion, and it can be interpreted qualitatively by the two quasiparticle plus rotor model including a J-dependent p-n residual interaction.

NUCLEON-NUCLEON CROSS SECTIONS IN ISOSPIN ASYMMETRIC NUCLEAR MATTER

The in medium nucleon-nucleon (N N) cross sections in isospin asymmetric nuclear matter at various densities are investigated in the frame work of Brueckner-Hartree-Fock theory with the Bonn B two-body nucleon-nucleon inter action supplemented with a new version microscopic three-body force (TBF). The TBF depresses the amplitude of cross sections at high density region. At low densities, the proton-proton and neutron-neutron cross sections decrease while the proton-neutron one increases as the asymmetry increases. But the sensitivity of the N N cross sections to the isospin a symmetry are reduced with the increasing density.

牛蒡根际土壤致害菌Fusariumsolani分离鉴定

目的:探索牛蒡根际镰刀菌与牛蒡之间的相互关系。方法:从全国30个地区采集牛蒡根际土壤样品,进行了根际土壤真菌数量和群落的生态学研究,测定镰刀菌发酵液对牛蒡幼苗和牛蒡子萌发的影响,并对其中毒性最强的两株镰刀菌F130和F131进行了形态学和分子生物学的鉴定。结果:镰刀菌为牛蒡根际的最优势类群,贡献率为34.297%,其次为木霉,贡献率为22.519%;绝大多数镰刀菌对牛蒡有明显的毒性作用,其中F130和F131被鉴定为Fusarium solani。结论:Fusarium solani是牛蒡根际土壤中的致害菌。

区域生态建设与景观生态学的使命

区域和景观尺度上的生态建设是指一定地域、跨生态系统、适用于特定景观类型的生态建设 ,即实行科学的生态系统管理和优化环境的建设工程 .近年来国家实施了一系列重大的生态工程项目 ,如天然林保护工程、部分地区退耕还林还草、内陆河流域的生态调水等 ,取得了显著的效果 .加强区域生态建设 ,维护国土安全已成为国家的战略需求 .依据不同类型区的特点应实行不同的生态建设战略 ,如生态敏感区、脆弱区和高人口密度的生态压力区 ,可分别实施以生态安全保障、生态负荷调整和生态秩序重建为重点的生态建设战略 ,调控人类活动 ,实行有序开发 ,统筹人与自然的和谐发展 .面对转型期的国家需求 ,我国景观生态学的发展迎来了挑战与机遇并存的重要契机 .研究的关键议题包括 :景观生态安全格局 ;土地利用与生态过程 ;人类活动胁迫下的景观变化 ;区域开发人类活动生态影响的定量评价 ;区域生态安全评价与预警 ;景观生态建设的模式设计与优化组合 .

土壤重金属污染及植物修复技术综述

阐述了我国土壤重金属污染现状及其危害,重点叙述了植物修复技术在土壤重金属污染的修复过程中的作用,并归纳该技术的优缺点,结合我国具体情况,提出植物修复技术的发展趋势。

STUDIES ON ORGANOLANTHANIDE COMPLEXES .40. SYNTHESIS AND X-RAY STRUCTURE OF BIS (2-METHOXYETHYLCYCLOPENTADIENYL) YTTRIUM AND YTTERBIUM TETRAHYDROBORATES

New bis (2-methoxyethylcyclopentadienyl) yttrium and ytterbium tetrahydroborates (Ln = Y, 1; Yb, 2) have been synthesized in good yield by the reaction of bis (2-methoxyethylcyclopentadienyl) lanthanide chlorides (Ln = Y, Yb) with sodium borohydride in THF at room temperature. The title complexes were characterized by elemental analyses, MS, H-1 NMR and IR spectra. The crystal structures of 1 and 2 have been determined by X-ray diffraction. 1 crystallizes from THF-n-Hexane in space group Pna2(1) with unit cell parametert: a = 1.2390(3), b = 1.1339(2), c = 1.1919 (2) nm and V = 1.6745(6) nm3 with z = 4 for D(c) = 1.39 g.cm-3.The structure was solved by direct method and refined to final R = 0.061 (for 1730 observed reflections). The Space group of 2 is Pna2(1) with unit cell parameters: a = 1.2399(6), b = 1.1371(5), c = 1.1897(2) nm and V = 1.6773(1) nm3 with z = 4 for D(c) = 1.72 g.cm-3, R = 0.038 (for 2157 observed reflections). The X ray structures and IR reveal the bidentate yttrium and ytterbium tetrahydroborate complexes with the intramolecular coordination bonds between lanthanide metal and ligand oxygen atoms.