土壤腐殖质的分析化学研究进展

对土壤腐殖质的分析化学研究进展进行了综述。具体包含如下几个方面的内容：土 壤腐殖质的组成和结构的研究，土壤腐殖质的起源和形成的研究，土壤腐殖质与土壤中有机、 无机物质的相互作用的研究以及有机物料的分解、转化及其对腐殖质影响的研究。同时，对土 壤腐殖质的研究中有待进一步用分析化学方法解决的几个问题进行了探讨。

Study on the beta relaxation mechanism of thermosetting polyimide thermoplastic polyimide blends

The thermosetting polyimide PMR-I5 and its blends with thermoplastic polyimides have been studied by dynamic mechanical analysis. The results obtained indicate that the level of beta relaxations in PMR-15 are increased with an increase in cross-linking density. This phenomenon is interpreted as a change of chemical structure during the cross-linking process. Addition of thermoplastic polyimide makes the magnitude of beta relaxations increase when PMR-15 is the major component. This might be due to the strong intermolecular charge-transfer interaction between PI and PI or PMR-15 and PMR-15 molecular chains being partly replaced by the weak intermolecular interaction between PI and PMR-15 in PMR-15/PI blends, resulting in some phenylene rings or imide groups in PIs and PMR-15 chains being able to participate in beta relaxation. However, this increment in beta relaxation magnitude can be reduced by heat treatment of the sample, as a result of phase separation. Hence, it is concluded that the beta relaxation magnitude is determined by the number of groups which can participate in relaxation per unit length, i.e. the magnitude of beta relaxation increases with decreasing interaction between the molecular chains. Copyright (C) 1996 Elsevier Science Ltd

吡咯在HOPG上电聚合机理的ECSTM现场观测

电聚吡咯过程机理的研究,多年来由于仪器的限制仅限于从间接的方式获得证据,为了得到溶液中真实的电聚吡咯过程信息,我们用自制的ECSTM仪器首次对电聚吡咯成膜的全过程跟踪观测,得到了有意义的结果。 1 实验条件 ECSTM仪器是本实验室在中科院北京电子显微镜实验室制造的STM基础上

铕(Ⅱ)在氟化镁钾基质中的格位取代过程及价态稳定性

Eu~(2+)电子跃迁发射与其所处基质的晶场环境和化学键性质密切相关。实验证明,(d→ff→f)两种发射的竞争,取决于Eu~(2+)在基质中占据的晶格位置。 KMgF_3是一种典型的钙钛矿结构复合氟化物,是理想的激光基质材料。在这种基质中掺

ELECTRODEPOSITION OF POLYCRYSTALLINE CD-RICH HG1-XCDXTE AND PHOTOELECTRO-CHEMICAL BEHAVIOR OF HG0.09CD0.91TE THIN-FILM

Electrodeposition process of polycrystalline Cd-rich Hg_(1-z)Cd_xTe (x>0.5) in acidic bath of CdSO_4+HTeO_2~+HgCl_2 was investigated. The simultaneous electrodeposition technique of three kinds of ions at the same potential has been achieved. The XRD, SEM and EDAX analysis of the thin film electrodeposited on titanium substrate showed a typical cubic zinc blende polycrystalline structure and homogeneous dispersion. The photoelectrochemical behavior of (1-x)=0.09 polycrystalline thin film in a polysulfide re...

Antioxidative principals of Jussiaea repens: an edible medicinal plant

Jussiaea repens L. (JRL) is an edible medicinal plant and is also used as a vegetable by the local people in southwestern China. The crude extract and its four fractions derived from JRL were evaluated for the 1,1-diphenyl-2-picrylhydrazyl radical-scavenging ability, hydroxyl radical-scavenging capacity and the potassium ferricyanide reduction property. The ethyl acetate-soluble fraction (EAF) and EAF6 (a subfraction derived from EAF) were the most valuable fraction and subfraction, respectively. Furthermore, bioactivity-guided chromatographic fractionation revealed that three pure compounds greatly contributed to the antioxidant activities. Qualitative and quantitative analyses of the major antioxidant constituents in the extract were systematically conducted by NMR, mass spectral analyses and RP-HPLC. The result demonstrated that rosmarinic acid (2.00 mg g(-1) JRL dry weight) quercetin 3-O-beta-D-glucopyranoside (9.88 mg g(-1) JRL dry weight), and kaempferol 3-O-beta-D-glucopyranoside (1.85 mg g(-1) JRL dry weight) were the major antioxidative constituents in JRL. These compounds are reported for the first time from this plant.

ISOLATION AND CHARACTERIZATION OF CHLORELLA SOROKINIANA GXNN01 (CHLOROPHYTA) WITH THE PROPERTIES OF HETEROTROPHIC AND MICROAEROBIC GROWTH

Heterotrophic and anaerobic microalgae are of significance in both basic research and industrial application. A microalga strain was isolated from a wastewater treatment pond and identified as Chlorella sorokiniana Shihira et W. R. Krauss GXNN01 in terms of morphology, physiology, and phylogeny. The strain grows rapidly in heterotrophic or mixotrophic conditions with addition of various carbon sources, and even in anaerobic conditions. The maximum growth rate reached 0.28 d(-1) when using D,L-malate as the carbon source, and the protein content of the microalgae was 75.32% in cell dry weight. The strain was shown to be capable of (1) utilizing D, L-malate only with light, (2) inhibiting photosynthesis in mixotrophic growth, and (3) growing in anaerobic conditions with regular photosynthesis and producing oxygen internally. This study demonstrates the influence of oxygen (aerobic vs. anaerobic) and metabolic regime (autotrophy, mixotrophy, heterotrophy) on the physiological state of the cell.

海藻中α-葡萄糖苷酶抑制剂的分离鉴定及其活性机理的研究

以α-葡萄糖苷酶抑制剂筛选模型为基础，以大型海藻为研究对象，旨在发现海藻中能够预防与治疗糖尿病以及抗艾滋病的活性物质。在对青岛沿海海藻脂溶性提取物进行了普筛的基础上，以石莼为原料追踪并分离鉴定了酶活性抑制剂SQG；建立了快速准确测定海藻中SQG的方法，并测定了一些大型藻中SQG的含量及季节变化，为选择提取SQG的原料提供了依据；建立了大量制备SQG的方法，为深入研究SQG的活性机理和 SQG进入动物试验阶段进行基础研究工作；研究并提出了SQG的酶抑制活性机理，为进行药理研究提供理论依据。本文的工作由六部分组成，研究内容介绍如下：1、采用α-葡萄糖苷酶抑制剂筛选模型对青岛沿海二十种海藻的脂溶性提取物进行了初步的活性筛选；初筛结果表明，海藻中普遍含有能够抑制α-葡萄糖苷酶活性的活性物质；2、对石莼中的活性组份进行了追踪并鉴定出了酶抑制活性物质1,2-二酰基-3-(6-脱氧-6-磺酸基-α-D-吡喃型葡萄糖苷基)-sn-甘油脂（SQG）。3、建立了快速准确直接测定SQG含量的方法。通过研究表明azure A比色法灵敏度高，检测限低（0.00442μmol），线性范围宽（0.00442-0.11488μmol），重现性好。4、测定了二十二种海藻中SQG的含量以及部分海藻SQG含量的季节变化，发现石莼中SQG含量较高并且受季节影响少。5、以石莼为原料建立了规模制备SQG的方法，为进一步研究SQG的生物活性奠定了基础。6、通过对SQG的酶抑制活性研究，首次测得SQG的IC_(50)为20μM。不同SQG浓度下酶动力学研究结果表明SQG对α-葡萄糖苷酶的抑制属于非竞争性抑制，抑制常数K_i为72.31μM；研究了SQG的构效关系并提出了SQG的酶抑制活性机理。

青海高原春小麦高产育种的商榷

在青海高原生态条件下，通过增加春小麦叶片净光合速率提高同化能力，以大穗大粒增大库的贮积能力，以矮秆配合良好光合性能和大贮积能力提高收获指数，使品种的源、流、库协调发展，达到培育高产品种的目的。

Development of 10 microsatellite loci for Rheum tanguticum (Polygonaceae)

Rhubarb is an important Traditional Chinese Medicine. However, the wild resource has been declining. In order to design appropriate conservation methods for the official species across their natural distributions, it is important to characterize their genetic diversity. Here, we describe the development of 10 new microsatellite loci for AC/TG/CCA in Rheum tanguticum. The microsatellites were enriched using the combined biotin capture method. The polymorphism of each locus was further assessed in 12 individuals from four geographically distinct populations of this species. The number of alleles ranged from three to seven and the expected heterozygosity ranged from 0.53 to 0.73. All markers have been checked in the other three species in the genus and two of them together comprise the official medicinal rhubarb resource, with R. tanguticum. These microsatellite markers could. provide a useful tool for genetic and conservation studies of the rhubarb species.

末次冰盛期以来中国东部沙地空间分布特征及环境记录

The latest two extreme scenarios of last glacial maximum and Holocene climatic optimum marked extreme situations in China. This paper aims to reconstruct the fossil extensions and paleoclimate of deserts in eastern China during this typical period. Aeolian sequence responds the climate change by virtue of alternation of aeolian sand layer and sandy soil layer, which correspond aridity and humidity, respectively. There is a set of contrastive deposits made up of loose sand layer and overlying dark sandy soil below land surface. This developed soil and underlying deep aeolian sand respond to H.O. and late last glacial, i.e. LGM. The typical bottom sand layers of about 50 profiles of Hulun Buir Desert, Horqin Desert and Otindag Desert were dated using OSL to confirm that they did deposid in LGM. Based on the locations of these LGM sand, distrution of gobi-desert-loess and landform control, the distribution in LGM of the three deserts were reconstructed. For the block of eastern mountain, the extreme eastern boundary of Hulun Buir Desert and Otindag Desert are not just functioned by climate background. The east of Horqin Desert is plain, hence eastern boundary of this desert is maily controlled by climate. It is considered that quite a lot of aeolian sand of LGM origined from fluvial deposit by observing regional distribution of river and SEM of sand grains. The environment alternation of of LGM-H.O. is featured by extensive expanse of active dune in LGM and grassland in H.O. Combined grain-size, susceptibility, TOC, colour and SEM measurement, the OSL chronology of relatively continued profiles since LGM of the three deserts are divided into four periods: eolian sand (15-10ka)- sandy soil (10-5ka)- alternation of black sand and yellow sand- reworking of LGM sand as destroy of soil.