高寒金露梅灌丛生物量及年周转量

采用样方调查与挖掘相结合的方法，以金露梅（Potentilla fruticosa）灌丛多年累积枝干、地下生物量和当年新生枝叶量及6-9月冠面长度、宽度和高度为参数进行线性回归分析，结合金露梅灌丛与草本植物在样地所占比例，估算其年净初级生产量及年净固碳量。结果表明：2004年金露梅灌丛地下实际周转量为53．7g／m^2，周转率为26％；当年新生枝叶量为41．0g／m^2，年净初级生产量94．7g／m^2；以草本植物与金露梅灌丛在样地所占比例为60％和40％进行估算，2004年金露梅灌丛草甸总净初级生产量为858．3g／m^2，固碳量481．9g／m^2。

Conformational analysis of 2,2 '-bithiophene under interaction of external electric field defined by point charges

Conformational analysis of 2,2'-bithiophene (BT) under the influence of an electric field (EF) constructed by point charges has been performed by using semi-empirical Austin Model 1 (AM1) and Parametric model number 3 (PM3) calculations. When the EF perpendicular to the molecular conjugation chain is applied, both AM1 and PM3 calculations show an energy increase of the anti-conformation. AM1 predicts that the global minimum shifts to syn-conformation when the EF strength is larger than a critical value. and PM predicts that the local minimum in anti-conformation vanishes. This kind of EF effect has been ascribed to the EF and dipole moment interaction.

SYNTHESIS AND X-RAY CRYSTAL-STRUCTURE OF [EU(ETA-6-C6ME6)(ALCL4)2]4 - THE 1ST CYCLOTETRAMERIC LANTHANIDE(II) COMPLEX WITH A NEUTRAL PI-LIGAND

The reaction of EuCl3, AlCl3 and C6Me6 in toluene gives the Eu(II) complex [Eu(eta-6-C6Me6)(AlCl4)2]4; X-ray crystal determination shows the molecule to be a cyclotetramer, in which the four Eu(C6Me6)AlCl4 units are connected via four groups of eta-2-AlCl4.