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L-threonine (2S,3S) was obtained from easily available L-threonine (2S,3R) after four steps,then seven chiral ligands 9a-9g were prepared by the esterification,condensation,reductive alkylation,cyclization,then reduction with treatment with RMgX.All seven kinds of novel compounds were characterized by 1HNMR,13CNMR,IR and HRMS.Compound 9a was further characterized by X-ray diffraction.The X-ray structure analysis revealed that an intermolecular hydrogen bond is present.

The direct strong steric interaction between substrate substituents and ligand substituents was first discovered in asymmetric addition of diethylzinc to aldehydes catalyzed by sterically congested ferrocenyl aziridino alcohol derivatives. In addition, this nonbonded steric repulsion influenced significantly enantioselectivities of this reaction, and even led to inversion of the absolute configuration. This fact was further confirmed by the theoretical calculations and the design of a new chiral ferrocenyl aziridino alcohol ligand. A plausible mechanism for this asymmetric reaction was also proposed.

A series of new optically active [2-(1-hydroxyalkyl)pyrrolidino]methylferrocenes were conveniently prepared from commercially available L-proline and ferrocenecarboxylic acid. The crystal structure of key intermediate was obtained. They were then applied to catalyze enantioselective addition of diethylzinc to arylaldehydes with enantio- selectivity up to 99%. The effects of the ligand structures on the enantioselectivity were also studied.

Plant phenology is the best indicator of terrestrial ecosystem response to climate change and it becomes a hot issue in the study of global change. The forest in northeast of China plays an important part in global forest ecosystem. In this paper, yearly integrated Normalized Difference Vegetation Index (NDVI) of forest vegetation in northeast China was calculated based on Spot Vegetation datasets from 2001-2010, which has been filtered using Savtiky-Galoy method. And then, the yearly integrated NDVI profile was fitted using a logistic model. Two key parameters of forest phenology (start of season, SOS; end of season, EOS) were extracted according to the greatest rate of curvature of fitted cumulative NDVI and the length of forest phenology (length of season, LOS) was also analyzed. The main conclusions of this paper are (1) SOS mainly occurs in the 110th-140th day and EOS in 260th and 290th day. SOS displays a marked delayed from south to north while EOS gradually advances. However, the changes of SOS and EOS in ten years are not obvious. (2) Corresponding to the SOS and EOS, LOS of forest in study area mainly occurs in the 120th-160th day; however, it is spatially heterogeneous. LOS of forest in Greater Khingan Mountains is shorter (about 120-140 day) than forests in Xiao Hinggan Ling and Changbai Mountains (about 160 day). The results in this paper are concordant with records of phenology in situ measurements and previous researches in the same area. It indicates that forest phenophases using method in this paper from Spot Vegetation dataset is feasible.

Leaf area index (LAI) is an important structural parameter of vegetation canopy, the correct estimation of which has been the focus in the remote sensing community. As a kind of hyperspectral and multi-angle remote sensing data with higher resolution (17 m), PROBA/CHRIS has significant application value in LAI inversion. In the present paper, the analytical two-layer canopy reflectance model (ACRM) was used to simulate a series of reflectances with different LAI values. Based on this, a new vegetation index was built and successfully applied to LAI inversion of PROBA/CHRIS image data. Our results indicated that: compared with the spectral index NDVI and multi-angle index HDS, the new index could make better use of spectrum and multi-angle messages and have a better correlation with LAI of the study area; moreover, the correlation coefficient R2 reached up to 0.734 7. And in order to obtain the figure of LAI distribution of the study area, we used the optimal fit equation between LAI and HDVI to estimate LAI, and the accuracy of the RMSE was 0.619 8.

A series of novel chiral C 2 -symmetric 1,1'-disubstituted ferrocenyl aziridino alcohols have been readily synthesized and applied as catalysts to promote enantioselective addition of diethylzinc to aldehydes affording thecorresponding 1-propanols in up to 99.5% enantiomeric excess with excellent yields. The effect of the ligand structure on the enantioselectivity was examined. The results showed that the C 2 -symmetric ferrocenyl β-amino alcohol ligands could produce an excellent asymmetric environment for the asymmetric addition of diethylzinc to aldehydes. The absolute configuration of chiral C 2 -symmetric ferrocenyl aziridino alcohol ligand 8j was confirmed by X-ray diffraction analysis.

The title compound, C14H21Cl3O9·2H2O, is a disaccharide constructed from a galactose and a fructose. In the molecular structure, the tetrahydrofuran five-membered ring and tetrahydropyran six-membered ring assume envelope and chair conformations, respectively. An extensive O—H...O hydrogen-bonding network occurs in the crystal structure.