51 resultados para 839


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土壤质量维持和改良是农林业生产面临的重要问题。利用海洋枯草芽孢杆菌(Bacillus subtilis)3728、3512、海洋木霉(Trichoderma sp.)TF4和少量白三叶草(Trrifolium repens)制成海洋微生物复合制剂,对当年生桉树人工林进行了生物调控试验。结果表明:海洋微生物复合制剂对土壤微生物数量和群落结构具有调节作用;曲霉、木霉、毛霉等与纤维素分解相关的真菌数量增加,镰刀菌数量减少;细菌数量比对照增加1.0倍,其中枯草芽孢杆菌增加2.02倍,蜡样芽孢杆菌增加1.18倍;放线菌数量增加0.3倍;土壤有机质含量、铵态氮含量和速效磷含量增加,土壤中蔗糖酶、蛋白酶、脲酶的活性显著提高;施用180d后测定桉树树高和胸径变化,树高净增加量比对照高12.6%,表明海洋微生物复合制剂作为生物调控剂对桉树生长具有一定促进作用。

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采用室内培养方法研究还原型谷胱苷肽(GSH)对黑土和棕壤磷酸酶动力学特性的影响。结果显示480mgkg-1(以风干土重计)的GSH处理的黑土磷酸单酯酶、三酯酶和棕壤的二酯酶、三酯酶Vmax值显著大于对照,证明GSH是通过增大酶量实现Vmax值的增大。试验中GSH处理的棕壤磷酸单酯酶及黑土的磷酸二酯酶Km值显著低于对照,说明GSH改变了酶结构,增强了酶与底物的亲和力。

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采用盆栽试验,研究了2种含钾土壤条件下不同有机酸对茄子产量和生长发育的影响。结果表明:通过叶面喷施有机酸可提高茄子单果重,改善植株的生长发育状况。其中,有机酸钾、甲酸、柠檬酸、乙酰丙酸与对照之间有显著差异;高钾土壤高于低钾土壤产量,且差异显著。有机酸的增产效果依次为有机酸钾>甲酸>柠檬酸>乙酰丙酸>草酸>丙酸>乙酸。

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采用相似性系数和物种多样性指数对新疆博格达山地面生苔藓植物的物种多样性进行了研究 .结果表明 ,博格达山地区苔藓植物区系具有丰富性和复杂性的特点 ,共有地面生苔藓植物 32科 73属 186种 (含变种、变型 ) ;山地荒漠带和山地草原带苔藓植物物种相似性最高 ,为 0 .6 80 9,山地森林带和高山垫状植被带相似性最低 ,仅为 0 .1342 ;山地森林带苔藓植物在整个博格达山地面生苔藓植物群落中占据优势地位 ;山地森林带苔藓植物物种多样性最为丰富 ,为该山地苔藓植物多样性的分布中心 ,是苔藓植物多样性保护的关键地区

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陆地生态系统的水循环与碳循环是地球表层系统物质循环与能量交换的核心,也是最基本的耦合的两个生态学过程。区域或全球尺度生态系统的水管理与碳管理是全球变化科学与可持续发展研究的两大主题,是人类维持全球生态系统的物质与能量循环、自然资源循环再生的重要生态学途径。我们在综合评述现代应用生态学研究的发展趋势,陆地生态系统水和碳循环与生态系统管理关系的基础上,提出了陆地生态系统水循环与碳循环过程管理的内容与思路,阐述了生态系统水和碳耦合循环机制与模拟综合研究的新设想。

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An anionic water-soluble polyfluorene derivative, poly(9,9-bis(6'-phosphatehexyl)fluorene-alt-1,4-phenylene) sodium salt (PFHPNa), was synthesized by Suzuki coupling reaction in DMF/water. Polymer PFHPNa was well soluble in water with a strong blue fluorescence emission. Effect of the side chain length on fluorescence sensory properties was studied by comparing quenching efficiencies toward different quenchers of PFHPNa with a reported polymer poly(9,9-bis(3'-phosphatepropyl)fluorene-alt-1,4-phenylene) sodium salt (PFPPNa), which have different side chains in length. For small molecular quenchers (methylviologen, MV2+) and meso-5,10,15,20-tetrakis-(N-methyl-4-pyridyl)porphine (TMPyP4), polymer PFHPNa had lower sensitivity due to the much longer side chain length. The positively charged metalloprotein cytochrome c could quench fluorescence of conjugated polymers via energy transfer and electron transfer.

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The encapsulation of a rare earth (RE) complex Eu(DBM)(3)phen in modified S1-MCM-41 with 3-aminopropyltriethoxysilane is reported for the first time. The luminescence intensity of the RE complex in the modified Si-MCM-41 is about 9 times as strong as in unmodified Si-MCM-41 and the luminescence of the RE complex in the modified SI-MCM-41 has good color purity.

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It was found that at neutral pH the hydroxylation reaction rate of phenol was accelerated with an increase of the amounts of 1,4-quinone (1,4-BQ), This acceleration was ascribed to the formation of semiquinone from 1,4-BQ. The semiquinone and 1,4-BQ were suggested to play a role of actual oxidant (electron transfer) in the catalytic cycle. With further reaction, most 1,4-BQ was converted into 1,4-hydroquinone (HQ) and the corresponding mechanism was proposed.

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Crosslinkable side-chain liquid crystalline polyesters PCn from N-[n-(4-(4-nitrophenylazo)phenyloxy)alkyl]diethanolamine (Cn, n = 3, 5, 6, 10) as mesogenic monomers and maleic anhydride were synthesized and characterized. The thermal properties of PCn's were studied by means of DSC, polarized optical microscopy (POM) and wide angle X-ray diffraction (WAXD), and the results showed that all the polymers studied exhibit enantiotropic liquid crystallinity. In the molar mass independent region, the relatively high content of cis -CH=CH- groups in the polymer backbone of PC3 causes an increase of the melting temperature (T-m) and a decrease of T-g and isotropisation temperature (T-i). The crosslinking of PCn in the radical polymerization with styrene was confirmed by FTIR spectroscopy. The absorption band at 1300 cm(-1) attributed to the in-plane C-H-bending vibration of trans -CH=CH- in the polymer backbone disappeared after crosslinking, indicating that the trans -CH=CH- functions are consumed in the crosslinking polymerization of styrene.

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C_(60)及其相关衍生物的生物活性研究具有重要意义.由于C_(60)分子本身是非极性的,难溶于常见的极性溶剂,使得它在生物化学领域的研究和应用受到很大的限制.合成出水溶性的C_(60)衍生物将很好地解决这一问题.1993年Friedman等人发现水溶性C_(60)衍生物[HOCO(CH_2)_2CONH(CH_2)_2-C_6H_4]_2C_(61)具有抗HIVP的作用.黄文栋等人报道了水溶性C_(60)-脂质体对人子宫颈癌细胞具有很强的杀伤效应.最近,Chiang等人采用化学发光的方法研究了多羟基C_(60)衍生物——富勒醇吞噬超氧阴离子自由基的功效,结果表明富勒醇对黄嘌呤/黄嘌呤氧化酶产生的超氧阴离子自由基具有良好的清除作用,有关富勒醇对羟基自由基的清除作用研究未见报道.

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A new compound KMgLa(PO4)(2), isotypic with monoclinic LaPO4, is reported. Its cell parameters have been determined from X-ray powder diffraction data. Crystallization occurs in the monoclinic space group P2(1)/n (No. 14) with a = 6.839(3) Angstrom, b = 7.066(1) Angstrom, c = 6.523(3) Angstrom, beta = 103.42(4)degrees, and Z = 2. It was found that the KMgLa(PO4)(2) phase was isostructural with monoclinic LaPO4. The difference between them was that half of the La atoms in LaPO4 were couplingly substituted with the same amount of Mg and K atoms. This isomorphous substitution was confirmed by IR and Eu3+-doped excitation and emission spectra and by elemental analysis of single crystals. The spectroscopic data were compared with those of LaPO4:Eu3+. (C) 1995 Academic Press, Inc.

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Poly(2-acrylamido-hexadecylsulfonic acid) (PAMC16S) forms a stable monolayer on a pure water surface. More closely packed monolayers can be obtained when the subphase contains Cd2+ or Ca2+. Self-assembled monolayers have been formed on gold surfaces and characterized by contact angle measurement, XPS and electrochemical analysis. The results show that the monolayers are hydrophobic with the hydrophilic sulfonic acid groups adjacent to the metal surfaces and with the hydrocarbon chains extended from the surfaces. The monolayers exhibit great adsorption stability during the faradaic reactions, illustrating the advantage of polymeric LB films in potential applications.

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Complete mitochondrial genome plays an important role in the accurate revelation of phylogenetic relationships among metazoans. Here we present the complete mitochondrial genome sequence from a sea cucumber Apostichopus japonicus (Echinodermata: Holothuroidea), which is the first representative from the subclass Aspidochirotacea. The mitochondrial genome of A. japonicus is 16,096 bp in length. The heavy strand consists of 31.8% A, 20.2% C, 17.9% G, and 30.1% T bases (AT skew = 0.027: GC skew = 0.062). It contains thirteen protein-coding genes (PCGs), twenty-two transfer RNA genes, and two ribosomal RNA genes. There are a total of 3793 codons in all thirteen mitochondrial PCGs, excluding incomplete termination codons. The most frequently used amino acid is Leu (15.77%), followed by Set (9.73%), Met (8.62%), Phe (7.94%), and Ala (7.28%). Intergenetic regions in the mitochondrial genome of A. japonicus are 839 bp in total, with three relatively large regions of Unassigned Sequences (UAS) greater than 100 bp. The gene order of A. japonicus is identical to that observed in the five studied sea urchins, which confirms that the gene order shared by the two classes (Holothuroidea and Echinoidea) is a ground pattern of echinoderm mitochondrial genomes. Bayesian tree based on the cob gene supports the following relationship: (outgroup, (Crinoids, (Asteroids, Ophiuroids, (Echinoids, Holothuroids)))). (C) 2009 Elsevier B.V. All rights reserved.