腐植酸复合肥在春小麦上的增产效果

<正> 目前,对化学肥料进行二次加工,发展多元复合专用肥料,是世界肥料发展的大趋势,根据FAO(联合国粮农组织)肥料年鉴的统计数字,1989年、1990年度世界发达国家以复混肥料形态的N、P_2O_5、K_2O分别占肥料消费施用总量的20.4％-87.8％、79.2％-98.3％和36.5％-99.6％,而1992年,我国复混肥料施用量占化肥总量的15.8％,尚低于世界平均水平,而且主要是依赖进口。针对上述情况以及三江平原岗平地白浆土“板、瘦、硬”的具体特点,八五二农场天华腐植酸

基模势对luxAB标记的快生型大豆根瘤菌在土壤中存活的影响

经接合转移将luxAB基因插入快生型大豆根瘤菌 (Rhizobiumfredii)染色体 ,取可高效结瘤固氮的R .frediilux3菌株用于分子生态学研究 .在不同基模势下 ,研究了lux3在土壤中的存活 ,基模势为 - 30和 - 750kPa时 ,lux3在灭菌土中的生存能力明显 (P<0 .0 5)高于未灭菌土 ,当基模势为 - 1 50 0kPa时 ,土壤是否灭菌对lux3的存活影响没有差异 .不同基模势对lux3活性影响显著 ,在 - 1 50 0kPa的未灭菌土中 ,随着饥饿时间延长 ,可恢复活性的细菌数量显著下降 .同时比较了测定微生物活性的 3种方法 (即生物发光、脱氢酶活性和微生物呼吸 ) ,发光值变化与活细胞密度变化一致 ,PLf值 (即潜在发光 ,Potentialluminescence)反映了可恢复活性的饥饿种群密度 .luxAB基因是一种比较简便而实用的标记

节杆菌K1108乙内酰脲酶产酶条件研究

研究了乙内酰脲酶产生菌节杆菌K1 1 0 8的产酶条件。该菌乙内酰脲酶为诱导酶 ,存在于细胞内 ,乙内酰脲水解酶和N 氨甲酰氨基酸水解酶是同时被诱导产生。最适诱导物为5 苄基乙内酰脲 ,而 5 吲哚甲基乙内酰脲和 5 苯基乙内酰脲等不能诱导其酶的产生。筛选到一种安慰诱导物 ,诱导活性提高了 2倍多。对产酶培养基进行了筛选和优化 ,在最适条件下 ,K1 1 0 8产酶能力可达 1 0 8U mL。

黄土丘陵沟壑区林地水文生态效应

根据安塞水土保持试验站1993～2002年林地径流小区的降雨产流产沙的定位观测资料及2002年土壤含水量资料,分析了不同树种对坡面尺度降雨产流产沙及土壤水分的影响。结果表明:场降雨径流小区的产流量、产沙量与降雨量具有较好的相关性;多元回归分析表明,场降雨产流量和产沙量与降雨量和最大30min雨强的乘积呈正相关,与植被覆盖度呈负相关,场降雨产沙量回归方程复相关系数为0.253,各处理场降雨产流量回归方程复相关系数的变化范围为0.465～0.723,均达到了极显著的水平(P<0.01)。同时,各树种均具有良好的减流减沙功能,与农地相比,年均产流量和产沙量分别减少4.8%～52.9%和26.8%～86.0%;沙棘纯林及其混交林的减流减沙效益优于油松纯林。同时,沙棘纯林及其各混交林在造林初期就表现出良好的减流减沙效益,随着树龄的增长,其作用更加明显;而油松纯林在造林初期作用不明显,甚至出现产流量和产沙量大于农地的现象,但随着树龄的增长,减流减沙作用逐渐呈现并增大。沙棘纯林及其混交林30cm以下土壤含水量在整个生长季中均呈递减趋势,生长季初(4月份)土壤含水量最高,而生长季末(10月份)降到最低值。2002年沙棘纯林的...

农林复合系统植物竞争研究进展

植物竞争是农林复合系统成功和可持续性的主要决定因素。使资源竞争最小化,资源利用最大化,是农林复合系统提高产量和总生产力的核心。本文对农林复合系统中林木-作物间对光、水分和养分的竞争作用、化感作用及与竞争相关的植物特性进行了综述。一般认为,在湿润地区,农林复合系统地上部分对光的竞争可能是系统生产力的主要决定因素;而在温带地区和半干旱热带地区,地下部分对水分的竞争可能限制着系统的生产力。在农林复合系统中,植物对光的竞争能力由叶面积、冠层结构等决定,对土壤水分和养分的竞争能力则取决于植物根系所占据的土壤空间、根系的形态和生理塑性、植物根系在土壤中的时空分布格局等。今后应加强不同区域农林复合系统中不同组分间的竞争作用的比较、竞争过程及生理机理、化感作用、菌根影响植物竞争的作用和机理、地上部分竞争和地下部分竞争的相互作用、全球变化与植物竞争等方面的研究。

Effects of nitrogen fertilization on soil respiration in temperate grassland in Inner Mongolia, China

Nitrogen addition to soil can play a vital role in influencing the losses of soil carbon by respiration in N-deficient terrestrial ecosystems. The aim of this study was to clarify the effects of different levels of nitrogen fertilization (HN, 200 kg N ha(-1) year(-1); MN, 100 kg N ha(-1) year(-1); LN, 50 kg N ha(-1) year(-1)) on soil respiration compared with non-fertilization (CK, 0 kg N ha(-1) year(-1)), from July 2007 to September 2008, in temperate grassland in Inner Mongolia, China. Results showed that N fertilization did not change the seasonal patterns of soil respiration, which were mainly controlled by soil heat-water conditions. However, N fertilization could change the relationships between soil respiration and soil temperature, and water regimes. Soil respiration dependence on soil moisture was increased by N fertilization, and the soil temperature sensitivity was similar in the treatments of HN, LN, and CK treatments (Q (10) varied within 1.70-1.74) but was slightly reduced in MN treatment (Q (10) = 1.63). N fertilization increased soil CO2 emission in the order MN > HN > LN compared with the CK treatment. The positive effects reached a significant level for HN and MN (P < 0.05) and reached a marginally significant level for LN (P = 0.059 < 0.1) based on the cumulative soil respiration during the 2007 growing season after fertilization (July-September 2007). Furthermore, the differences between the three fertilization treatments and CK reached the very significant level of 0.01 on the basis of the data during the first entire year after fertilization (July 2007-June 2008). The annual total soil respiration was 53, 57, and 24% higher than in the CK plots (465 g m(-2) year(-1)). However, the positive effects did not reach the significant level for any treatment in the 2008 growing season after the second year fertilization (July-September 2008, P > 0.05). The pairwise differences between the three N-level treatments were not significant in either year (P > 0.05).

The microstructure and mechanical properties of Mg-3Al-3RE alloys

The Mg-3Al-3RE alloys (RE, the cerium-rich or the yttrium-rich misch metal) were smelted in a resistance furnace under the protective flux from the Mg-RE master alloys and pure magnesium ingots. The microstructure and mechanical properties of samples prepared by steel mould casting method were investigated.

Electrochemiluminescence in the S2O82- system: Pt-Cd electrodes

The electrochemiluminescence (ECL) in the S2O82- system occurs under conventional cyclic voltammetry, when the Pt working electrode was coated with Cd elementary substance. The ECL mechanism was proposed, due to the reaction between the strongly oxidizing intermediate SO4 center dot- and the transitory production, CdO, generated by oxidation of Cd with SO4 center dot-. Moreover the ECL behavior was studied in different pHs and concentrations of S2O82- solution. It was showed that the ECL signal was strongest at pH 8.0, and its intensity increased with S2O82-. The experimental results verified well with the proposed ECL mechanism.

Low temperature preparation of ceria solid solutions doubly doped with rare-earth and alkali-earth and their properties as solid oxide fuel cells

A series of solid electrolytes, (Ce(0.8)Ln(0.2))(1 - x)MxO2 - delta(Ln = La, Nd, Sm, Gd, M:Alkali-earth), were prepared by amorphous citrate gel method. XRD patterns indicate that a pure fluorite phase is formed at 800 degreesC. The electrical conductivity and the AC impedance spectra were measured. XPS spectra show that the oxygen vacancies increase owing to the MO doping, which results in the increase of the oxygen ionic transport number and conductivity. The performance of ceria-based solid electrolyte is improved. The effects of rare-earth and alkali-earth ions on the electricity were discussed. The open-circuit voltages and maximum power density of planar solid oxide fuel cell using (Ce0.8Sm0.2)(1 - 0.05)Ca0.05O2 - delta as electrolyte are 0.86 V and 33 mW . cm(-2), respectively.

Local structure and valences of samariurn in SrB4O7 : Sm and SrB6O10 : Sm prepared in-air

The coordination numbers for the samarium atoms and the Sm-O bond distances in SrB4O7:Sm and SrB6O10:Sm prepared in air were determined by means of Sm-L-3 edge EXAFS. The coordination. was found to be nine-folded for both these hosts and the bond distance was 2.40-2.42 Angstrom in SrB4O7:Sm and 2.42-2.44 Angstrom in SrB6O10:Sm. For SrB4O7:Sm the coordination number is coincident with that of the strontium. atoms suggesting the substitution of the samarium atoms at the strontium sites. The coordination number of the strontium atoms in SrB6O10 was also suggested to be nine assuming the same type of substitution. The valences of samarium were determined from the luminescent spectra. Both divalent and trivalent ions were present in both SrB4O7:Sm and SrB6O10:Sm, while the fraction of Sm2+ was higher in the former than in the latter. This difference has been assigned to the difference in rigidity between the B-O networks in these structures.

Aromatic poly(ester imide)s and poly(amide imide)s having 1,1 '-binaphthyl-2,2 '-diyls in the main chain

Full Paper: Two new 1,1'-binaphthyl-2,2'-diyl-based dianhydrides, i.e., 2,2'-bis(3,4-dicarboxybenzamido)-1,1'-binaphthyl dianhydride (BNDADA) and 2,2'-bis(3,4-dicarboxybenzoyloxy)-1,1'-binaphthyl dianhydride (BNDEDA), were synthesized and polymerized with various aromatic diamines to afford polyimides through the traditional two-step method. The polyimides with inherent viscosities ranging from 0.27 to 0.70 dl . g(-1) showed excellent solubilities in polar solvents such as DMAc, DMSO and NMP etc., except of the poly(ester imide) prepared from BNDEDA and benzidine. Poly(ester imide)s based on BNDEDA can also be readily dissolved in weakly polar solvents such as THF, CH2Cl2 and CHCl3. The glass transition temperatures of these polyimides are in the range of 210-310 degrees C; the 5% weight loss temperatures are in the range of 390-465 degrees C in nitrogen and 384-447 degrees c in air. These polymers from light yellow, tough films that were transparent above 365 nm. The effects of different flexible units attached in the 2- and 2'-positions, i.e., amide, ester and ether, on the properties of the polyimides obtained are discussed.

异丁烷-丁烯烷基化反应催化剂的研究Ⅳ.Zr(SO_4)_2和Zr(SO_4)_2/Al_2O_3(SiO_2)

制备了一系列不同焙烧温度的 Zr(SO4) 2 及 Zr(SO4) 2 负载量不同的 Zr(SO4) 2 / Al2 O3(Si O2 )固体强酸催化剂 ,用 XRD、IR、BET、TG- DTA、NH3- TPD、Hamm ett指示剂等方法研究了该催化体系的晶型、结构、比表面、酸量及酸强度随负载量和焙烧温度的变化规律 .将 Zr(SO4) 2 负载在 Al2 O3和 Si O2 两种载体上呈现不同的特性 .在 Al2 O3上明显地延缓了 Zr(SO4) 2 的分解和 Zr O2的晶相转变 .并且使酸量和酸强度有所提高 .研究了异丁烷 -丁烯烷基化反应 ,结果表明 ,对 973和 10 2 3K焙烧的 Zr(SO4) 2 样品 ,活性最好 ,而对 Zr(SO4) 2 / Al2 O3,负载量在 m(Zr(SO4) 2 ) /m(Al2 O3) =0 .5 / 1.0左右时活性最好 .各种样品均具有较高的 C08选择性.

Gas-phase ion-molecule reactions of C-60 with the plasma of methyl acrylate

The gas-phase ion-molecule reactions of C-60 with the plasma generated from methyl acrylate under self-chemical ionization conditions were studied by use of a triple-quadrupole mass spectrometer. The adduct cation [C60C3H3O](+) and protonated molecular ion [C60H](+) were observed as the major product ions. The former adduct ion is formed by electrophilic reaction of C-60 with the ion [CH2=CHCO](+), a main fragment ion resulting from the methyl acrylate molecular ion [CH2=CHCOOCH3](+) through alpha cleavage. The latter ion is generated by proton transfer from protonated methyl acrylate to C-60. Semi-empirical quantum chemical calculations have been performed for the eight possible isomers of [C60C3H3O](+) at the Hartree-Fock level by use of the AMI method. The results show three types of cycloadducts as the most stable structures among the possible isomers.

Optically active poly(amide-imide)s containing axially dissymmetric 1,1 '-binaphthyl moieties

Novel optically active aromatic poly(amide-imide)s (PAIs) were prepared from newly synthesized 2,2'-bis(3,4-dicarboxybenzamido)-1,1'-binaphyl dianhydride ((+/-)-, (S)-, and (R)-BNDADA). PAIs based on dianhydride monomers with different ee % were investigated with respect to their structures and chiroptical properties. These polymers were highly soluble in polar aprotic solvents such as N,N-dimethylacetamide, N-methyl-2-pyrrolidone, pyridine, etc., and showed high glas s transition temperatures of 287-290 degrees C and 5% weight loss temperatures of 450-465 degrees C in nitrogen. Optically active PAIs exhibited high specific rotations, excellent optical stabilities, and a dependence of optical activities on temperature. Investigations on chiroptical properties indicated that chiral conformation was possessed by optically active PAIs. (C) 1999 John Wiley & Sons, Inc.