990 resultados para 341.584
Resumo:
针对东北玉米等主要作物低温冷害的防御 ,研制出了一种新型植物生长调节剂———抗低温助长剂。采用人工低温模拟试验 ,3个地点、3种浓度、不同施用期的多处理联合田间试验和示范区示范 ,证明该制剂能增加叶片可溶性糖含量 ,降低电导率 ,增加叶绿素含量 ,提高光合速率 ,增强抗低温能力。促生长、促早熟、增产效果显著 ,可使玉米等作物提早成熟 5~ 6d ,正常年增产 6 %~ 11% ,低温年增产 15 %左右。施用时以 1∶4 0 0倍液和营养生长期间两次(拔节期和大喇叭口期 )喷施为最佳方案。
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分别合成了稀土(Eu3+和Tb3+)与柠檬酸、1,10 菲咯啉配位的稀土配合物。通过元素分析和红外分析确定了配合物的组成。通过荧光光谱与荧光寿命的测试,研究了它们的荧光性质。结果表明当铽掺入配合物后,铽能极大地增强铕的特征荧光,而铽的荧光被严重猝灭,其荧光强度以指数形式衰减。铕的荧光在铽荧光猝灭最严重时,被增强的效果最好,铕的荧光强度是荧光增强效果和铕的含量共同作用的结果,当铕与铽的浓度比为6∶4时能得到相应的铕的荧光最强的配合物。
Resumo:
9,10-Phenanthrenequinone (PQ) supported on graphite powder by adsorption was dispersed in propyltrimethoxysilane-derived gels to yield a conductive composite which was used as electrode material to fabricate a PQ-modified carbon ceramic electrode. In this configuration, PQ acts as a catalyst, graphite powder guarantees conductivity by percolation, the silicate provides a rigid porous backbone, and the propyl groups endow hydrophobicity and thus limit the wetting region of the modified electrode. Square-wave voltammetry was exploited to investigate the pH-dependent electrochemical behavior of the composite electrode and an almost Nernstian response was obtained from pH 0.42 to 6.84. Because the chemically modified electrode can electrocatalyze the reduction of iodate in acidic aqueous solution (pH 2.45), it was used as an amperometric sensor for the determination of iodate in table salt. The advantages of the electrode are that it can be polished in the event of surface fouling, it is simple to prepare, has excellent chemical and mechanical stability, and the reproducibility of surface-renewal is good.
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Crystallization behavior and spherulitic structure of linear high-density polyethylene (HDPE), after being irradiated in its molten state by gamma -rays, was investigated by small-angle laser scattering (SALS) and differential scanning calorimetry (DSC). Significant changes in the crystallization of HDPE during cooling in air before and after being irradiated in the melt were observed. A critical minimum average molar mass between cross-links (200 carbon-carbon bonds) for spherulite formation in such an irradiated HDPE network was obtained.
Resumo:
The complex, K2.5Na2NH4[Mo2O2S2(cit)(2)]. 5H(2)O (1), was obtained by crystallization from a solution of (NH4)(2)MoS4, potassium citrate (K(3)cit) and hydroxyl sodium in methanol and water under an atmosphere of pure nitrogen at ambient temperature. The crystals are triclinic, space group
, a = 7.376 (3)Angstrom, b = 14.620 (2) Angstrom, c = 14.661 (1) Angstrom, alpha = 71.10 (1)degrees, beta = 81.77 (1)degrees, gamma = 78.27(2)degrees, R = 0.0584 for 2545 observed (I > 2 sigma (I)) reflections. Single crystal structure analysis reveals that citrate ligand coordinated to molybdenum atom through two carboxylato oxygens and one deprotonated hydroxyl oxygen together with two bridging sulfur atoms and a terminal oxygen atom completes distorted coordination octahedron around each molybdenum atom. Principal dimensions are: Mo = O-t, 1.707 Angstrom (av); Mo-S-b, 2.341 Angstrom (av); Mo-O-(hydroxyl), 2.021 Angstrom (av); Mo-O(alpha-carboxyl), 2.1290 Angstrom (av) and Mo-O(beta-carboxyl), 2.268(av) Angstrom. IR spectrum is in agreement with the structure.
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The aqueous complexation of lanthanide complexes of citrate in pH 7.4 solutions has been studied by using lanthanide-induced shift and relaxation times measurement methods. These results indicate that citrate coordinate via 3-hydroxyl and 3-carboxylate groups with lanthanide ions and form 1:2 (Ln/cit) isostructural complexes through lanthanide series. We suggest a new coordination geometry which is different from that described in literature.
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用稀土离子诱导位移和顺磁弛豫时间测定等NMR方法研究了稀土柠檬酸配合物在pH7.4的溶液中的配位结构.结果表明稀土离子通过3-羟基和3-羧基与柠檬酸配体形成1:2的配合物,两个端羧基没有参与配位.通过计算稀土离子和柠檬酸配体中各个碳原子间的空间距离的相对比,建立了稀土离子与柠檬酸配体配位的新模式.
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ESR和自旅捕捉技术用于研究活体动物犬心肌缺血再灌产生的自由基,PBN从冠状静脉血液中捕捉到了OH自由基,直接地证实了缺血再灌细胞膜损伤的活性氧自由基作用机制;实验还看到一种甾体皂甙药物具有保护心肌细胞.防止自由基损伤的功能.
ELECTROCHEMICAL STUDY OF ISOPOLYMOLYBDATE(VI) ANION TRANSFER ACROSS THE WATER/NITROBENZENE INTERFACE
Resumo:
Isopolymolybdate (VI) anion transfer across the water/nitrobenzene (w/n) interface was studied by cyclic voltammetry. The effect of pH and responsed kinetics of isopolymolybdate anion's formation in the water phase on the transfer behavior have been studi
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本文研究了温度和压力对五种六氟二酐(6FDA)型聚酰亚胺膜对H_2、CO_2、O_2、N_2和CH_4五种气体透过性能的影响.在30-100℃区间,五种聚酰亚胺的透气系数与温度的关系均符合Arrhenius关系式;在0.3-1.2MPa区间,压力对透气系数的影响很小.6FDA-4,4'-二氨基二苯酮(DABP)和6FDA-3,3'-二甲基二苯甲烷二胺(DMMDA)在100℃仍然具有较大的透气选择系数,是比较好的气体分离膜材料.
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本文简要地总结了近期聚苯硫醚共混物的研究结果。着重讨论了聚苯硫醚共混物的物理性能和潜在的用途。
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用电子束加热沉积法(EBD)制备了厚度420um的ZnIn2ZTe4薄膜。研究了最佳成膜工艺条件和性能,用电子能谱(XPS)分析了ZuIn2Te4薄膜的组成、结构和状态;典型ZnIn2Te4膜最佳参数为:电阻率ρ为3.2×10-1Ω·cm,Hall迁移率是79cm2V-1s-1,载流子浓度是1.58×1017cm-3,禁带宽度(Eg)是2.33eV;探讨了ZuIn2Te4膜导电机理,制作了ZuIn2Te4-Si太阳能电池。