放牧和封育条件下科尔沁沙地小叶锦鸡儿群落土壤种子库特征

以科尔沁沙地小叶锦鸡儿群落为研究对象,对比分析了放牧干扰和不同封育年限下土壤种子库特征。结果表明:①放牧和封育样地土壤种子库均以一年生植物为主,物种丰富度没有明显差异;②放牧样地土壤种子库密度为(3 475±519)粒/m2,封育6年和封育12年样地土壤种子库密度分别为(20 241±1 714)粒/m2和(28 777±3 946)粒/m2,显著高于放牧样地;③Shannon-W iener多样性指数、S impson多样性指数和P ielou均匀度指数在放牧样地分别为1.36,0.68和0.56,并随着封育年限的增加而降低;④放牧和封育样地土壤种子库主要分布于0~2 cm的土壤表层,封育样地各层的种子库密度均显著高于放牧样地;⑤放牧和封育样地土壤种子库均为聚集分布,但放牧样地种子库的空间异质性高于封育样地。

Molecularly imprinted monolithic stationary phases for liquid chromatographic separation of enantiomers and diastereomers

The method for preparation of molecularly imprinted monolithic stationary phase has been improved to achieve liquid chromatographic separation of enantiomers and diastereomers. By adopting low polar porogenic solvents of toluene and dodecanol and optimal polymerization conditions, the molecularly imprinted monolithic stationary phases with good flow-through properties and high resolution were prepared. Enantiomers of amino acid derivatives and diastereomers of cinchona alkaloids were completely resolved using the monolithic stationary phases. The influence of porogenic composition, monomer-template ratio and polymerization conditions on the chromatographic performance was investigated. Some chromatographic conditions such as the composition of the mobile phase and the temperature were characterized. Scanning electron microscopy showed that the molecularly imprinted monolithic stationary phase has a large through-pore structure to allow the mobile phase to flow through the column at very low backpressure. Accelerated separations of enantiomers and diastereomers were therefore achieved at elevated flow rates. Finally, the chiral recognition performance of the prepared stationary phase in aqueous media was investigated. Hydrophobic interaction, and ionic and/or hydrogen bonding interactions were proposed to be responsible for the recognition mechanism. (C) 2002 Elsevier Science B.V. All rights reserved.

海洋光合细菌Rx菌株的分离鉴定与生物学特性研究

　从大连金州区海湾养虾池底分离获得光合细菌Rx菌株的初筛菌株,并对其纯培养物进行了形态特征、培养特征、生理生化特征以及DNA中G+C摩尔百分比等生物学特性分析。结果表明,Rx菌株为革兰氏阴性菌,大小为(0.5～0.7)μm×(1.0～1.2)μm,单极生鞭毛,光合内膜为泡囊状,繁殖方式为二分分裂生殖;Rx菌株的纯培养物含细菌叶绿素a和球状素型类胡萝卜素,光照厌氧和黑暗好氧条件均能生长;Rx菌株生长盐度为5～100g/kg,生长pH为5.8～8.4;Rx菌株不能利用硫化物为电子供体,其生长受高浓度硫化物的抑制;能利用谷氨酸而不能利用柠檬酸钠、酒石酸为有机碳源或电子供体;盐酸硫胺素(t)、生物素(b)、p-对氨基苯甲酸(p-ABA)、烟酸(n)为Rx菌株生长的必需因子;Rx菌株DNA的G+C摩尔百分比为64.18%。根据以上特征,并参照《常见细菌系统鉴定手册》(2002)和《伯杰氏细菌系统学手册》第3卷(1989),将Rx菌株鉴定为小红卵菌属广海小红卵菌(Rhodovulumeuryhalinum)。

Affinity membrane chromatography for the analysis and purification of proteins

Affinity chromatography is unique among separation methods as it is the only technique that permits the purification of proteins based on biological functions rather than individual physical or chemical properties. The high specificity of affinity chromatography is due to the strong interaction between the ligand and the proteins of interest. Membrane separation allows the processing of a large amount of sample in a relatively short time owing to its structure, which provides a system with rapid reaction kinetics. The integration of membrane and affinity chromatography provides a number of advantages over traditional affinity chromatography with porous-bead packed columns, especially with regard to time and recovery of activity. This review gives detailed descriptions of materials used as membrane substrates, preparation of basic membranes, coupling of affinity ligands to membrane supports, and categories of affinity membrane cartridges. It also summarizes the applications of cellulose/glycidyl methacrylate composite membranes for proteins separation developed in our laboratory. (C) 2001 Elsevier Science B.V. All rights reserved.

缓/控释氮素肥料对土壤生物学活性的影响

采用盆栽试验方法,研究施用不同种缓/控释氮素肥料对玉米苗期土壤脲酶、硝酸还原酶活性、微生物生物量碳和氮的影响。结果表明:在玉米苗期,施用脲酶抑制剂(NBPT)涂层大颗粒尿素、硝化抑制剂(DCD)与NBPT混合涂层大颗粒尿素肥料对脲酶活性有显著的抑制作用,脲酶活性为48～50mgNH3-N·kg-1土·24h-1;施用DCD与NBPT混合涂层大颗粒尿素肥料,硝酸还原酶活性最高,为1.43μgN·g-1土·24h-1,施用含有NBPT肥料对硝酸还原酶活性没有显著影响。玉米苗期施用NBPT涂层尿素肥料微生物量碳、氮含量最高,分别为241和57mg·kg-1土,NBPT对土壤微生物量没有产生负面影响。施用不同种缓/控释氮素肥料微生物量氮变化与微生物量碳一致,施用DCD与NBPT混合涂层大颗粒尿素肥料微生物量氮与对照无显著差别,为50mg·kg-1土。施用DCD与NBPT混合涂层大颗粒尿素肥料,玉米苗期微生物固持氮素能力没有受到影响,同种膜材料包膜NBPT/DCD涂层尿素制成的控释氮肥,对土壤生物学活性影响明显强于直接包膜大颗粒尿素制成的控释氮肥的作用效果。不同种缓/控释肥料玉米苗期土壤生物学活性差异表明,丙烯酸树脂包膜尿素制成的控释氮肥,对氮素或抑制剂的控释效果显著好于醋酸酯淀粉包膜尿素制成的控释氮肥。

Transient state of chiral recognition in a binary mixture of cyclodextrins in capillary electrophoresis

The transient state (as the defined point where no enantioseparation is obtained in a dual chiral selector system) of chiral recognition of aminoglutethimide in a binary mixture of neutral cyclodextrins (CDs) was studied by capillary electrophoresis (CE). The following three dual selector systems were used: alpha-cyclodextrin (alpha-CD) and beta-cyclodextrin (beta-CD); alpha-CD and heptakis(di-O-methyl-beta-cyclodextrin) (DM-beta-CD); alpha-CD and heptakis(tri-O-methyl-beta-cyclodextrin) (TM-beta-CD). The S-(-) enantiomer of the analyte was more strongly retained in the presence of either alpha-CD or TM-beta-CD at pH 2.5, 100 mM phosphate buffer, while the R-(+) enantiomer was more strongly retained in the presence of either P-CD or DM-P-CD. In the more simple case, the elution order is invariably kept if the enantiomers have the same elution order in either one of the two hosts of the binary mixture. In contrast, the elution order may be switched by varying the concentration ratio of two hosts that produce opposite elution order for this particular analyte. In such a dual selector system, the enantioselectivity will disappear at the transient state at a certain ratio of host,:host, Moreover, the migration times of the two enantiomers with host, alone (diluted in buffer) is approximately equal to the migration times at the corresponding concentration of host, alone (diluted in buffer), where the ratio of concentrations of host,:host, is the same as in the binary mixture at the transient state. As found by nuclear magnetic resonance experiments, the analyte is forming a 1:1 complex with either one of the CDs applied. From this finding, a theoretical model based on the mobility difference of the two enantiomers was derived that was used to simulate the transient state. (C) 2000 Elsevier Science B.V. All rights reserved.

Synthesis and characteristics of the human serum albumin-triazine chiral stationary phase

Human serum albumin (HSA) was successfully bonded to silica with s-triazine as activator. The coupling reaction by this method was rapid and effective. The triazine-activated silica is relatively stable and can be installed for at least 1 month without obvious loss of reactivity when stored below 30 degreesC, pH below 7. It was observed that the amount of bound HSA reached 120 mg/g silica calculated from the UV absorbance difference of the HSA solution. d,l-tryptophan was selected as the probe solute to characterize the properties of HSA bonded s-triazine chiral stationary phase, and separation factor of 9.4 was obtained for d,l-tryptophan. Furthermore, the amount of effective HSA on silica was measured by high-performance frontal analysis, and only 16.8 mg/g silica was responsible for the resolution of d,l-tryptophan. These results indicate that the amount of both the bound and effective HSA on silica with triazine as activator was much higher than those by the Schiff base coupling method. Different kinds of enantiomers were resolved successfully on the aminopropylsilica-bonded HSA s-triazine chiral stationary phase. (C) 2000 Wiley-Liss, Inc.

科尔沁沙地南缘樟子松(Pinussylvestrisvar.mongolica)人工林天然更新障碍

针对科尔沁沙地南缘樟子松人工林不能天然更新的特征,从森林天然更新的必要条件出发,通过种子萌发、幼苗存活与生长所需条件的系列试验,探讨了科尔沁沙地南缘樟子松人工林不能天然更新的障碍特征。结果表明,沙地樟子松人工林不能天然更新的主要原因有:(1)由于土壤的干旱胁迫使沙地樟子松人工林中天然下种的种子很少有萌发的机会,尤其是在春季;(2)在水分条件相对充足的季节(秋季),樟子松种子能够萌发,但萌发产生的更新幼苗数量极少,即便这些更新幼苗得以存活,但由于沙地表层(0~5cm)与樟子松共生的外生菌根菌几乎不能存活而导致幼苗根系无法形成菌根,从而致使存活的樟子松幼苗抗旱、抗病能力非常弱,不能越冬,即不能更新。

林带疏透度模型及其应用

在应用数字图象处理法测定东北西部典型杨树林带疏透度的基础上，采用逐步回归分析和推理方法分别构筑了疏透度与林带结构因子相关的主导因子模型和因配置方式和树种而异的机理模型，并阐述了两种模型在林带结构调控中的作用．

中国大陆苔类植物新记录科─—顶苞苔科及其地理分布

在研究我国西南地区苔藓植物时，首次在中国大陆发现钝角顶苞苔（Ａｃｒｏｂｏｌｂｕｓｃｉｌｉａｔｕｓ（Ｍｉｔｔ．）Ｓｃｈｉｆｆｎ．），顶苞苔科亦为中国大陆的新记录，其地理分布也进行了探讨。

algorithms for computing weak bisimulation equivalence

IEEE Comp Soc, IFIP, Tianjin Normal Univ

Spatial-temporal characteristics of siping urban expansion based on remote sensing and GIS

Based on the RS and GIS methods, Siping city is selected as a study case with four remote sensing images in 25 years. Indices of urban morphology such as fractal dimension and compactness are employed to research the characteristics of urban expansion. Through digital processing and interpreting of the images, the process and characteristics of urban expansion are analysed using urban area change, fractal dimension and compactness. The results showed that there are three terms in this period. It expended fastest in the period of 1979~1991, and in the period of 1992~2001, the emphases on urban redevelopment made it expended slower. And this is in agreement with the Siping Statistical Yearbook. This indicates that the united of metrics of urban morphology and statistical data can be used to satisfactorily describe the process and characteristics of urban expansion. © 2008 IEEE.