易旱地区褐土P、Zn形态转化特点及其与持续农业的关系

采用田间微区试验和分级提取测定的方法研究了褐土中Ｐ、Ｚｎ形态转化问题．发现褐土中Ｃａ２－Ｐ和Ｃａ８－Ｐ是转化最活跃的Ｐ素形态．而且Ｃａ８－Ｐ的流通容量很大，可超过作物需Ｐ量９倍以上；在Ｚｎ的各种形态中转化最活跃的是ＥＸ－Ｚｎ和ＣＡＲＢ－Ｚｎ，其中ＣＡＲＢ－Ｚｎ的流通容量亦很大，可超过作物需Ｚｎ量１９倍以上．Ｃａ８－Ｐ库和ＣＡＲＢ－Ｚｎ库形成了褐土中调控Ｐ、Ｚｎ养分供蓄以适应旱地水分波动的主要机构．合理施肥和培肥土壤以丰富Ｃａ８－Ｐ和ＣＡＲＢ－Ｚｎ库将有利于增强作物抵御干旱能力，提高水分养分利用效率，促使旱地农业持续向高产优质高效方向发展．

应用GUS基因研究弗氏中华根瘤菌的结瘤及效果

应用GUS(葡萄糖苷酶 )基因标记技术将标记基因GUS导入受体菌S .fredii8855,标记菌株形成的根瘤可被GUS染色缓冲液染成蓝色 ,而土著菌形成的根瘤不能着色 .由此即可十分简便地确定土著菌的影响程度 .盆栽试验表明 ,S .fredii 8855的结瘤抗酸碱能力高于土著菌 ,能在土壤中较大范围内迁移 .当它的根瘤占有率不小于 43%时 ,接种能显著提高大豆产量 ,大豆产量与根瘤占有率呈正相关 (r=0 .98) ,而与总瘤数关系不大 (r=0 .1 3) .土壤N素显著抑制其结瘤 ,补加P能缓解这种抑制作用 .

樱桃砧木根癌病敏感性评价方法

建立了樱桃砧木对农杆菌敏感性的评价方法,在5种樱桃砧木,对樱桃(Prunus.pseudocerasus)、CAB(P.cerasus)、Gisela5、Gisela6(P.cerasus×P.canescens)、colt(P.avium×P.pseudocerasus)的组培苗茎上接种野生型农杆菌(C58),40d后调查结瘤百分率和瘤重,基于结瘤百分率和病情指数评价了供试材料的敏感性,结果表明:该方法能反映不同砧木的抗性水平,可作为樱桃砧木根癌病敏感性评价、筛选抗性种质的一种有效的方法。

真菌生命之树项目(AssemblingtheFungalTreeofLife)和美国真菌系统学研究现状

<正>美国的现代真菌系统学研究始于上世纪九十年代初期,以一系列分子系统学文章的发表为标志,其中代表性的工作有Vilgalys&Gonzalez(1990),White et al.(1990),Bruns et al.(1992),

中国能源保障水平分区初探

在经济高速增长的新形势下,能源保障风险日益凸现。全国能源保障分区研究不仅是能源风险管理的基本要求,也是经济发展对能源产业提出的新要求。本文阐述了全国能源资源的基础形势,并对1996年~2005年间我国一次能源生产和消费情况进行了分析;构建了由能源储量比、对外依存度、库存增减量、能源生产弹性系数、能源消费弹性系数、运输线路长度6个指标组成的能源保障指标体系,采用因子分析法确定各个指标的权重;并根据灰色聚类方法对全国30个省(市、区)"十五"期间的能源保障能力进行了评估与分区。结果表明:我国能源保障水平具有南

Micelle-assisted synthesis of polyaniline/magnetite nanorods by in situ self-assembly process

Polyaniline/magnetite nanocomposites consisting of polyaniline (PANI) nanorods surrounded by magnetite nanoparticles were prepared via an in situ self-assembly process in the presence of PANI nanorods. The synthesis is based on the well-known chemical oxidative polymerization of aniline in an acidic environment, with ammonium persulfate (APS) as the oxidant. An organic acid (dodecylbenzenesulfonic acid, DBSA) was used to replace the conventional strong acidic (1 M HCl) environment. Here, dodecylbenzenesulfonic acid is used not only as dopant, but also as surfactant in our reaction system.

Blends based on sulfonated poly[bis(benzimidazobenzisoquinolinones)] and poly(vinylidene fluoride) for polymer electrolyte membrane fuel cell

A new blend system consisting of an amorphous sulfonated poly[bis(benzimidazobenzisoquinolinones)] (SPBIBI) and the semi-crystalline poly(vinylidene fluoride) (PVDF) was prepared for proton exchange membranes. The miscibility behavior of a series of blends of SPBIBI with PVDF at various weight ratios was studied by WXRD, DSC and FTIR. The properties of the blend membranes were investigated, and it was found that the introduction of PVDF in the SPBIBI matrix altered the morphological structure of the blend membranes, which led to the formation of improved connectivity channels. For instance, the conductivity of the blend membrane containing 10 wt% PVDF displayed the highest proton conductivity (i.e., 0.086 S cm(-1)) at room temperature, a value almost twofold that of the pristine SPBIBI membranes (i.e., 0.054S cm(-1)) under identical conditions.

Investigations of the properties of Mg-5Al-0.3Mn-xCe (x=0-3, wt.%) alloys

Mg-5Al-0.3Mn-xCe (x = 0-3, wt.%) alloys were prepared by metal mould casting method. The microstructures and mechanical properties were investigated. The results revealed that the main phases of as-cast Mg-5Al-0.3Mn alloy consist of alpha-Mg matrix and beta-Mg17Al12 phase. With the addition of Ce element, Al11Ce3 precipitates were formed and mainly aggregated along the grain boundaries. The amount of the Al11Ce3 precipitates increased with increasing addition of Ce, but the amount of beta-Mg17Al12 phase decreased. The highest tensile strength was obtained in Mg-5Al-0.3Mn-1.5Ce alloy. The ultimate tensile strength (UTS), yield strength (YS) and elongation at room temperature are 203 MPa, 88 MPa and 20%, separately.

Relaxation time and conductivity of comb-like gel polymer electrolytes

Using the copolymer of acrylonitrile (AN), methyl methacrylate (MMA), and poly(ethylene glycol) methyl ether methacrylate as a backbone and poly(ethylene glycol) methyl ether (PEGME) with 1100 molecular weight as side chains, comb-like gel polymers and their Li salt complexes were synthesized. The dynamic mechanical properties and conductivities were investigated. Results showed that the gel copolymer electrolytes possess two glass transitions: alpha-transition and beta-transition. Based on the time-temperature equivalence principle, a master curve was constructed by selecting T. as reference temperature. By reference to T-0 = 50 degrees C, the relation between log c, and c was found to be linear. The master curves are displaced progressively to higher frequencies as the content of plasticizer is increased. The relation between log tau(p) and the content of plasticizer is also linear.

Effect of cerium on microstructure and electrochemical performance of Ti-V-Cr-Ni electrode alloy

Effect of cerium on the microstructure and electrochemical performance of the Ti0.25V0.35-xCexCr0.1Ni0.3 (x = 0, 0.005) electrode alloy was investigated by X-ray diffraction (XRD), field emission scanning electron microscopy/energy dispersive X-ray spectrometry (FESEM-EDS), and electrochemical impedance spectroscopy (EIS) measurements. On the basis of XRD and FESEM-EDS analysis, the alloy was mainly composed of V-based solid solution with body-centered-cubic structure and TiNi-based secondary phase. Ce did not exist in two phases, instead, it existed as Ce-rich small white particles, with irregular edges, distributed near the grain boundaries of the V-based solid solution phase. Discharge capacity, cycle stability, and high-rate discharge ability of the alloy electrode were effectively improved with the addition of Ce at 293 K. It was very surprising that the charge retention was abnormal with larger discharge capacity after standing at the open circuit for 24 h. EIS indicated that addition of Ce improved the dynamic performance, which caused the charge transfer resistance (R-T) to decrease and exchange current density (I-0) to increase markedly. The exchange current density of the electrochemical reaction on the alloy surface with Ce addition was about 2.07 and 3.10 times larger than that of the alloy without Ce at 303 and 343 K, respectively.

CPE-g-HEA/TDI热塑性弹性体的制备和性能研究

采用氯化原位接枝法合成主链为氯化聚乙烯(CPE)、支链为丙烯酸-2-羟基乙酯（HEA）的官能化接枝聚合 物(CPE-g-HEA),制备CPE-g-HEA/2,4-二异氰酸甲苯酯（TDI）热塑性弹性体,并对其性能进行研究。结果表明, CPE-g-HEA/TDI热塑性弹性体的物理性能较好;与溶液法产物相比,共混法CPE-g-HEA/TDI热塑性弹性体的强度 较大、相对分子质量较小、相对分子质量分布较宽,热行为基本无变化;共混法CPE-g-HEA/TDI热塑性弹性体的反 应温度应控制在60～70℃,共混次数(即打三角包次数) 为150次时拉伸强度较高、80次时拉断伸长率较高,HEA/TDI摩尔比为1/0.5时拉伸强度较高。

Negative differential resistance and memory effect in diodes based on 1,4-dibenzyl C60 and zinc phthalocyanine doped polystyrene hybrid material

Negative differential resistance (NDR) and memory effect were observed in diodes based on 1,4-dibenzyl C60 (DBC) and zinc phthalocyanine doped polystyrene hybrid material. Certain negative starting sweeping voltages led to a reproducible NDR, making the hybrid material a promising candidate in memory devices. It was found that the introduction of DBC enhanced the ON/OFF current ratio and significantly improved the memory stability. The ON/OFF current ratio was up to 2 orders of magnitude. The write-read-erase-reread cycles were more than 10(6), and the retention time reached 10 000 s without current degradation.