预知灵对小白鼠肝微粒体LPO及SOD活性的影响

分别给小鼠以大、中、小剂量的预知灵溶液灌胃,测定肝微粒体脂质过氧化物(LPO)及超氧化物歧化酶(SOD)的活性,来探讨预知灵对小白鼠肝微粒体LPO及SOD的影响.试验结果表明,大、中剂量的预知灵和人参煎液均能显著降低肝微粒体LPO水平并提高其SOD的活力.提示预知灵和人参煎液有抗衰老作用,并且预知灵抗衰老作用明显优于人参煎液(P<0.01).     

Stacking interaction in metal complexes with compositions of DNA and heteroaromatic N-bases

The current development in the intramolecular aromatic-ring stacking i nteractions in the complexes with compositions of DNA and heteroaromatic N-bases has been reviewed to a great extent, especially the significant contributions i n several important systems about ternary mixed-ligand complexes, including nucl eotide-metal ion-po- lyaromatic amine, amino acid-metal ion-polyaromatic amine, nucleotide-metal ion-pyridine-like aromatic amine, nucleotide-metal ion-amino ac id, nucleotide-metal ion-nucleic acid base, nucleic acid base-metal ion, and the important factors affecting the intramolecular aromatic-ring stacking interacti ons in the complexes. Based on the study of stacking interaction in the complexe s, the mechanism of interaction between DNA molecules and complexes of heteroaro matic N-bases has been established, which is crucial for the design and synthesi s of the complexes acting as molecular devices of DNA.     

过渡金属与吗啉二硫代甲酸吗啉的配合物的合成及性质

过渡金属的氯化物(或硫酸盐)与吗啉二硫代甲酸吗啉(mcrpholinedithiocarbamic aid, morpholine salt)在水溶液中反应制备出7个新配合物(M=Mn~(2+),Cu~(2+),Cu~(2+),Ni~(2+),Zn~(2+),Cd~(2+),Hg~(2+))。通过红外光谱、紫外光谱、差热—热重分析及部分配合物的溶度积常数的测定对配合物进行了性质鉴定。结果表明,所有7个配合物中配体均以二齿与金属离子蛰合配位,中心离子的配位数是4。     

后过渡金属烯烃聚合均相催化剂的负载化研究进展

综述了后过渡金属烯烃聚合均相催化剂的负载化研究进展.将高活性的后过渡金属均相催化剂负载于SiO2、Al2O3、MgCl2、聚硅氧烷、聚苯乙烯、环糊精等无机和有机载体材料上,所形成的负载催化剂一方面能够充分利用现有的烯烃多相聚合工业化装置(淤浆和气相聚合),另一方面能够发挥均相催化剂高活性的优点.近年来,后过渡金属均相催化剂的负载化日益引起学术界和工业界的重视,具有广阔的发展前景.     

Preparation of long-branched polyethylene byin situ polymerization using late transition metal and metallocene catalysts

An in situ polymerization method was investigated to prepare long-branched polyethylene (LBPE) with ethylene alone and a single cocatalyst, methylalumoxane (MAO), by using a dual functional catalytic system containing late transition metal oligomerization catalyst and metallocene copolymerization catalyst. The obtained long-branched polyethylene has the characteristics of low melting point, high activity and well-dispersed sequence distribution.     

La2Mo2O9的离子掺杂行为研究

以柠檬酸为络合剂,采用溶胶-凝胶法合成了La2Mo2O9以及La2Mo2-xMxO9(M=Fe、Mn、Ti、Co、Ni、W)掺杂的样品.应用X射线衍射(XRD)、差示扫描量热(DSC)等方法考察了离子掺杂的成相情况以及离子搀杂对La2Mo2O9结构的稳定化作用;运用双探针法测试了样品的电导率随温度的变化情况.研究结果表明Fe、Mn、Ti、Co、Ni等离子对Mo6 的取代掺杂量较少.纯La2Mo2O9在580℃左右存在相变,但Fe、Ti掺杂样品没有出现相变过程的吸热峰.W6 离子可取代部分Mo6 而进入La2Mo2O9晶格,但对抑制其相变没有作用.     

Analyses of nitrobenzene, benzene and aniline in environmental water samples by headspace solid phase microextraction coupled with gas chromatography-mass spectrometry

Nitrobenzene, benzene and aniline are widely used in chemical industries as solvents and reaction interme- diates. Their discharge or leakage to the environment will result in serious environmental pollution, so it is very important to propose a fast and …     

过渡金属掺杂的立方型ZrO_2催化剂处理含酚废水

采用共沉淀法制备了一系列过渡金属(Cu,Mn,Co,Fe,Ni,Cr)掺杂的ZrO2催化剂,XRD表征.表明属于立方型ZrO2结构.在250 mL间歇式反应釜中,反应温度150℃,初始压力为3.5 MPa,反应时间90 min的条件下,对苯酚(2.1 g/L,COD质量浓度为5 000 mg/L)的催化湿式氧化结果为:COD去除率为12.6%~83.1%.其催化活性顺序为:Cu-ZrO2>Mn-ZrO2>Co-ZrO2>Ni-ZrO2>Cr-ZrO2>Fe-ZrO2.研究了催化剂Cu-ZrO2在不同反应条件下对COD去除率的影响.     

水溶液中相转化制备六方相三氧化钼及其电化学嵌锂性质

三氧化钼(MoO3)以三种常见的物相存在:正交相、六方相和单斜相,前者为热力学稳定相,后两者为热力学介稳相.相对于稳定的正交相MoO3,介稳的六方相MoO3较难制备.笔者采用对已商品化的正交相MoO3再次结晶的方法制得了纯六方相MoO3.通过透射电镜(TEM)观察可知产物为均匀的纳米棒.实验结果表明合成的六方相MoO3的首次放电容量比商品化的正交相MoO3高.六方相MoO3有望成为理想的锂离子电池阴极材料.     

Effects of metal ions and heat shock on the expression of a metallothionein-like gene htMT2 in Helianthus tuberosus

The expression of htMT2 in tissues of Helianthus tuberosus treated with metal ions and heat shock is studied by Northern blot hybridization. The results indicate that htMT2 is not expressed in roots. The expression in leaves and stems can be reduced by Cu2+ and induced by low concentration of Zn2+. However, the expression of htMT2 can be suppressed by Zn2+ when its concentrations are above 500 μmol/L. The effects of Ca2+ on the expression of htMT2 in leaves are similar to that of Zn2+. But Ca2+ induces the expression of htMT2 in stems. The expression levels of htMT2 in various tissues are not significantly affected by heat shock. The results above demonstrate that the expression of htMT2 can be regulated by metal ions and confirm that htMT2 is a new metallothionein-like gene.     

锡替代钴对DyCo2合金的结构和磁热效应的影响

通过X射线衍射和磁性测量研究了D y(Co1-xSnx)2(x=0.025,0.040,0.050,0.075,0.080,0.100)合金的相结构和磁热性能.经分析可知Sn在D yCo2中的替代是有限的,X射线粉末衍射分析确定试样由D yCo2,D yCo3和D y5Sn3三相组成,D yCo2为主要相.随着Sn成分的增加,杂质相D yCo3和D y5Sn3的含量增加.试样D y(Co0.975Sn0.025)2保持一级磁相变,其他所有试样保持二级磁相变.Sn的替代使居里温度稍微有所提高,从142 K(x=0)到148 K(x=0.080).在外加磁场2 T的作用下,试样D y(Co1-xSnx)2(x=0.025,0.040,0.050)最大磁熵变值分别为5.46,4.10和3.96 J.kg-1.K-1.     

北京市三环沿线油松叶片重金属的累积特征、季节变化和来源解析

城市绿化植物松树能够净化城市空气和土壤重金属污染,常被作为监测城市环境质量的指示植物。分别在2009年6月、2009年9月、2009年12月和2010年3月在北京市三环沿线采集油松(Pinus tabulaeformis)松针样品,进行重金属分析,并采用主成分分析对重金属的来源进行解析。结果发现,三环地区油松样品中存在重金属Pb、Cd和Hg污染,且具明显季节变化,冬季污染最严重。源解析结果表明冬季和秋季时,植物中重金属污染源主要为土壤源、交通源和燃烧源,其源贡献率约占40%、20%和20%。春季和夏季时,植物中重金属污染源主要为土壤源和交通源,其源贡献率约占40%和20%。     

高能有效真二次电子发射系数与逸出深度和入射角的关系

根据金属二次电子发射的主要物理过程和有效真二次电子发射系数的定义,从理论上论述了高能原电子斜射入金属发射体内的金属的有效真二次电子发射系数的表达式,然后又根据高能原电子斜轰击金属并激发产生二次电子发射的特点,推导出金属的有效真二次电子发射系数与金属逸出深度和高能原电子入射角度的关系式.对结果进行了讨论并得出结论:当高能原电子斜射入金属发射体内时,金属的有效真二次电子发射系数与高能原电子的入射角的余弦函数近似成反比,金属的有效真二次电子发射系数与金属逸出深度近似成正比.     

从"草木虫鱼"看周作人创作心态的变化

从20年代到50年代，周作人以草木虫鱼为题材创作了一系列小品文，以搭建自己的文学园地。从其二十年代、三四十年代、五十年代三个不同时期的草木虫鱼创作中窥探隐藏在文字背后的真实，可从中反观周作人不同时期创作心态的变化。     

Energies, fine structures and transition wavelengths of the core-excited states in Be * ions

The fine structures of doubly excited resonances of lithium-like beryllium are calculated using the saddle-point and saddle-point complex-rotation methods. A restricted variational method is used to obtain a more accurate value for the nonrelativistic energy. Relativistic and mass polarization corrections to the resonance energy are included. Transition wavelengths are also calculated and compared with other theories and experimental results     

银硼磷玻璃系统的形成区、电导和离子传输研究

制备了AgX-Ag_2O-P_2O_5-B_2O_3(X=Br,Cl)系统快离子玻璃样品,确定了其玻璃的形成区,测量了该系统玻璃的离子电导率、迁移数、玻璃转变温度和红外光谱。提出了该系统中银离子迁移的结构模型,玻璃是BO_3、BO_4、PO_4基团和Ag~+离子、Br~-离子或Cl~-离子组成的。玻璃中AgX、Ag_2O和B_2O_3/P_2O_5含量越多,电导率就越大。电导率随组成的变化从结构和化学键的观点进行了解释。     

Bifurcation,several equilibria and multiple growth paths in the solow model with endogenous demographic transition

In this paper,the endogenous demographic transition function is integrated into the classical Solow model. It is proven that the differential equation which describes the model at least has a nonzero equilibrium. The differential equation has several equilibria when the technological level or the saving rate is not high enough and undergoes bifurcation at some specified parame-ter values. Therefore,the economy described by the model pre-sents multiple growth paths and Malthusian Poverty Trap when the technological level or the saving rate is low.