Ascofuranone增加HepG2细胞LDLR报告基因表达的生物活性的研究

以控制LDLR基因表达的调控元件SRE为靶位点 ,使用含有荧光素酶报告基因的转染人肝细胞系HepG2筛选模型高通量筛选微生物来源的能够增加低密度脂蛋白受体 (LDLR)基因表达的具有潜在的降胆固醇作用的生物活性物质。在筛选过程中 ,通过对一株真菌产生的化合物ascofuranone的研究发现该化合物对测活用细胞株的LDLR荧光素酶报告基因的表达有中等强度的激活作用 ,其SC150 为 40 .4μmol/L。Ascofuranone激活LDLR基因表达这一新的生物活性的发现为深入研究该化合物的降血脂作用提供了新的重要启示

The geometry of the NO2- anion: ab initio calculations and Franck-Condon analysis

Geometry optimization and harmonic vibrational frequency calculations have been performed on the (X) over bar (2)A(1) state of NO2 and (X) over bar (1)A(1) state of NO2-. Franck-Condon analyses and spectral simulations were carried out on the NO2((X) over bar (2)A(1))-NO2-((X) over bar (1)A(1)) photo detachment process. In addition, the equilibrium geometry parameters, r(NO)= 1.248 +/- 0.005 Angstrom and angle(ONO) 116.8 +/- 0.5degrees, of the (X) over bar (1)A(1) state of NO2-, are derived by employing an iterative Franck-Condon analysis procedure in the spectral simulation. Our conclusions regarding the anion geometry suggest a reinterpretation of the results of Woo et al. (C) 2004 Published by Elsevier B.V.

大兴安岭北坡林火迹地森林景观格局的变化

以黑龙江省图强林业局的育英和奋斗林场为研究区,从景观尺度上,以遥感和地理信息系统为技术手段,探讨和分析了1987年大兴安岭“5·6”特大森林火灾中,火烧强度对森林景观格局变化的影响。结果表明:火烧强度不同,导致种源、土壤理化性质等自然环境要素产生差异,并决定了火后森林景观更新与恢复的措施,进而影响森林景观格局的动态变化趋势。

东北地区药用苔藓植物资源及其开发利用前景

东北地区苔藓植物资源丰富 ,种类多 ,蕴藏量大 ,本文共记述了 4 6种药用苔藓植物 ,包括 6种苔类和 4 0种藓类 ,并对其生境、地理分布、药用功效等进行了初步讨论 ,认为东北地区药用苔藓植物资源具有巨大的潜在利用价值 ,而现有应用较为原始 ,应进行合理的开发与利用。

分期追施钾肥对烤烟生长和品质的影响

对豫西干旱区烤烟生长和品质的影响进行了研究,结果表明,团棵期和圆顶期分次施用钾肥与团棵期一次等量追施225kg·hm-2相比,上部叶片开片好,叶型趋同中部叶片,延伸叶片的宽度,降低叶片比叶重,增加了上部叶片的可用性,促进了根系活力和汲取土壤养分的能力,增加了光合速率和干物质积累,协调烤后叶片中化学成分比例,从而提高了烤烟的品质.

黑土区春小麦群体物质和能量积累研究

利用大田和实验室测定的方法,测定黑土区春小麦群体根、茎、叶、穗等物质和能量在整个生育期的积累过程,旨在为黑土区农业生态系统研究提供实测依据。结果表明,在整个生育期中,春小麦不同器官鲜物质积累的最大值出现的时期各异;除叶和20 cm以下根外,其它器官干物质累积均随生长发育而增加;各器官含水量差异较大,但都随生长而降低;每个器官能量的累积总量并不都是随生长发育而持续增长,且器官间单位干物质所含能量差异较大,变化范围为0.9×10~4 J·g~(-1)(根,孕穗期)至1.5×10~4 J·g~(-1)(叶,三叶期),根、秸秆、籽粒积累的能量分别为6.8×10~5、78.9×10~5和87.9×10~5 J·m~(-2),分别占总积累能量的3.9％、45.4％、50.7％。同实测法相比,计算法获得的秸秆能值高出31％。因此,测定法较计算法能更精确地反映能量在生态系统中的流动。

Matrix-assisted laser desorption/ionization mass spectrometry using porous silicon and silica gel as matrix

Porous silicon powder and silica gel particles have been applied as inorganic matrices for the analysis of small molecules in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOFMS). In contrast to conventional MALDI-TOFMS, the signal interference of low-molecular analytes by the matrix has been eliminated. Almost no fragmentations of the analytes were observed. Effects of various factors, such as the particle and pore size, the suspending solution, and sample preparation procedures, on the intensity of mass spectra have been investigated. The pore structure of the inorganic matrix and penetration of the analytes into the pores must be optimized for effective desorption and ionization of the analytes. Matrices (DHB and HCCA) were covalently bound to silica gel for improvement of spectrum intensity. Copyright (C) 2001 John Wiley & Sons, Ltd.

Data analysis for pump-probe experiment with femtosecond pulses

Various analytical physical models are presented to extract the photodissociation dynamics information from the data obtained in the femtosecond pump-probe experiment. The single- and double-component models are employed to explain the single- and double-channel dissociation of parent molecules. Another single-component model for fragment dissociation or deexcitation is also presented. All cases are explanatorily demonstrated on the pump-probe experimental data.