976 resultados para CHA-252
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A nickel molybdenum phosphate, (NH3CH2CH2NH3)(4).(NH3CH2CH2NH2). Na .[Ni2Mo12O30(PO4)(HPO4)(4)(H2PO4)(3)]. 6H(2)O, invoicing molybdenum present in V oxidation, has been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. Deep brown-red crystals are formed in the triclinic system, space group P (1) over bar, a = 12,011(2), b = 14,612(3), c = 21.252(4) Angstrom, alpha = 80.54(2)degrees, beta = 83.10(2)degrees, gamma = 76.29(2)degrees, V = 3561.4(12) Angstrom(3), Z = 2, lambda(MoK alpha) = 0.71073 Angstrom (R(F) = 0.0529 for 9880 reflections), Data mere collected on a Siemens P4 diffractometer at 20 degrees C in the range of 1.75 degrees < theta < 23.02 degrees using the omega-scan technique. The structure was solved by direct methods using the program SHELXTL-93 and refined with the method of fun-matrix least-squares on F-2. The structure of the title compound may be considered to be two [Mo6O15(HPO4)(H2PO4)(3)](5-) units bonded together with a nickel atom, although several P-O groups are not protonated on account of coordination with a Na+ cation, The one-dimensional tunnels were formed in the solid of the title compound. A probe reaction of the oxidation of acetaldehyde with H2O2 using the title compound as catalyst was carried out in a liquid- solid system, showing that the title compound had high catalytic activity in the reaction, (C) 1999 Academic Press.
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运用低能碰撞诱导解离(CID)研究了电子轰击(EI)、快原子轰击(FAB)电离条件下质子化亮氨酸与异亮氨酸解高产生亚稳离子[MH-CO2H2]+的单分子质谱碎裂,二种异构体呈现出了各自不同的解离特征,根据CID的特征碎片离子和氘代同位素标记实验,提出了其碎裂过程存在离子/中性(碎片)复合物中间体碎裂机理,并对有关的特征离子的形成进行了讨论.
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本文就微生物、荧火虫荧光素酶体参及荧光素体系在临床、生物化学及药物等方面分析检测中应用的最新进展进行了评述。荧光素酶既可以在溶液状态下也可以在固定/共固定状态下对各种酶、底物及辅因子进行分析检测、菌尿的测试、微生物及细菌污染检测;荧灭虫及微生物荧光素酶反应都已应用到免疫检测及诱变反应中。
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对羟基苯甲酸/对苯二甲酸/双酚A三元共聚酯的核磁共振表征吴大诚,谢新光,李瑞霞,王勇(成都科技大学纺织工学院成都610065)周子南,高新风,孝延文,张建国(中国科学院长春应用化学研究所高分子物理开放实验室长春130022)关键词对羟基苯甲酸/对苯二...
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The diffuse reflectance spectra of nanocrystalline Nd2O3 were measured in the ultraviolet-visible region, It is found that the part of f-->f transition bands were widened and red-shift occurred. The absorption tail-band in the region from 300 to 550 nm was assigned to the O-2p-->Nd-4f transition. The behavior of light-induced charge transfer and photovoltaic properties of nanocrystalline Nd2O3 were studied by the surface photovoltage spectroscopy (SPS) and electric field modulating SPS techniques. The SPS response shows two peaks at 330 nm(P-1) and 380 nm(P-2) in the UV-Vis range, The spectral features observed can be explained in terms of charge transfer and interband transition.
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The intrinsic viscosities of poly(ethylene oxide)-poly(vinyl acetate) blends (PEO-PVA) have been measured in chloroform as a function of molecular weights of blend components and compositions. The interaction parameters Delta b obtained from the modified Krigbaum and Wall theory and the differences between the intrinsic viscosities of polymer mixtures and the weight-average intrinsic viscosities of the two blend components were both used to characterize the extent of miscibility of the blend mixtures. (C) 1995 John Wiley and Sons, Inc.
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A novel modified electrode dispersed with ultrafine platinum particles on the surface of a 30-mu m carbon fibre microelectrode was investigated as an amperometric detector in capillary zone electrophoresis (CEEC) for determining hydrazines. The unique cha
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X-ray photoelectron spectra of the bioinorganic complexes of Na and La with N-acetylalanine and N-acetylvaline have been measured. It has been found that the spectra of the O 1s core level in the complexes of Na with these amino acids are very different from those in the complexes of La with the same amino acids. The results indicate that in the complexes of La with N-acetylalanine and N-acetylvaline, both the oxygen atoms from the carboxyl group and the oxygen atoms from the carbonyl group of the amino acids will directly coordinate to the La ion, whereas only the oxygen atoms from the carboxyl group of the amino acids can directly coordinate to the Na ion in the complexes of Na with N-acetylalanine and N-acetylvaline.
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利用DSC、WAXD、IR及POM等手段对梳型两亲聚合物聚(2-丙烯酰胺基十六烷磺酸)(PAMC_(16)S)的超分子结构作了研究,对其组织形式作了考察,结果表明聚合物表现出梳型聚合物典型的层状堆砌,给出了其堆砌模型,对其液晶性也作了讨论。
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本文报道了Cu(Ⅲ)配合物Na_4K[Cu(HIO_6)_2]·12H_2O和Cu(Ⅱ)配合物Na_6[Cu(HIO_6)_2]·13H_2O的电子光谱和光电子能谱。两配合物的电子光谱都有强的配体至金属的电荷迁移谱带。Cu(Ⅱ)配合物的反射光谱于615nm处具有较强的d-d吸收谱带,而Cu(Ⅲ)配合物的反射光谱在此范围内的吸收强度较弱。Cu(Ⅲ)配合物的Cu2p_(3/2)XPS的电子结合能为935.7eV,比Cu(Ⅱ)配合物的933.9eV要高1.8eV,对应于Cu3d~(10)L~2态,其中L为与Cu3d轨道对称相匹配的O2p组合轨道上的离域空穴,综合YBa_2Cu_3O_(7-δ)的Cu2pXPS,指出了用XPS对铜价态研究所得结果相异性的主要原因是由于样品表面高价态铜的易还原性所致。
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An electrochemical detector based on a polyaniline conducting polymer chemically modified electrode (PAn CME) was developed for use in flow-injection analysis and ion chromatography. Iodide, bromide, thiocyanate and thiosulphate are detected by using ion chromatography with a PAn CME electrochemical detector. The detection limits are 1, 5, 10 and 10 mgl-1, respectively. The CME response for electroinactive anions varies selectively with the mobile phase composition in flow-injection analysis. By this approach, perchlorate, sulphate, nitrate, iodide, acetate and oxalate can be detected conveniently and reproducibly over a linear concentration range of at least 3 orders of magnitude. The electrode is stable for over 2 weeks with no evidence of chemical or mechanical deterioration.
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研究了端羧基丁二烯-丙烯腈共聚物增韧环氧树脂(TER)与蓖麻油聚氨酯(PU)组成的互穿聚合物网络(IPN)的应力-应变行为、密度和溶胀行为。结果表明,在TER嵌段共聚物/PU(质量比)值为某一定值时,IPN表现出补强弹性体行为,它既有较高的强度,又有很高的伸长率,断裂能也达到最大值;IPN的密度高于按共混物加合法则计算的值,溶胀度则低于计算值,说明网络间存在着互穿。
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Arthrospira (Spirulina) (Setchell& Gardner) is an important cyanobacterium not only in its nutritional potential but in its special biological characteristics. An unbiased fosmid library of Arthrospira maxima FACHB438 that contains 4300 clones was constructed. The size distribution of insert fragments is from 15.5 to 48.9 kb and the average size is 37.6 kb. The recombination frequency is 100%. Therefore the library is 29.9 equivalents to the Arthrospira genome size of 5.4 Mb. A total of 719 sample clones were randomly chosen from the library and 602 available sequences, which consisted of 307,547 bases, covering 5.70% of the whole genome. The codon usage of A. maxima was not strongly biased. GC content at the first position of codons (46.9%) was higher than the second (39.8%) and the third (45.5%) positions. GC content of the genome was 43.6%. Of these sequences, 287 (47.7%) showed high similarities to known genes, 63 (10.5%) to hypothetical genes and the remaining 252 (41.8%) had no significant similarities. The assigned genes were classified into 22 categories with respect to different biological roles. Remarkably, the high presence of 25 sequences (4.2%) encoding reverse transcriptase indicates the RT gene may have multiple copies in the A. maxima genome and might play an important role in the evolutionary history and metabolic regulation. In addition, the sequences encoding the ATP-binding cassette transport system and the two-component signal transduction system were the second and third most frequent genes, respectively. These genomic features provide some clues as to the mechanisms by which this organism adapts to the high concentration of bicarbonate and to the high pH environment.
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Peptidoglycan recognition protein (PGRP) specifically binds to peptidoglycan and plays a crucial role in the innate immune responses as a pattern recognition receptor (PRR). The cDNA of a short type PGRP was cloned from scallop Chlamys farreri (named CfPGRP-SI) by homology cloning with degenerate primers, and confirmed by virtual Northern blots. The full length of CfPGRP-SI cDNA was 1073 bp in length, including a 5 ' untranslated region (UTR) of 59 bp, a 3 ' UTR of 255 bp, and an open reading frame (ORF) of 759 bp encoding a polypeptide of 252 amino acids with an estimated molecular mass of 27.88 kDa and a predicted isoelectric point of 8.69. BLAST analysis revealed that CfPGRP-S1 shared high identities with other known PGRPs. A conserved PGRP domain and three zinc-binding sites were present at its C-terminus. The temporal expression of QPGRP-S1 gene in healthy, Vibrio anguillarum-challenged and Micrococcus lysodeikticus-challenged scallops was measured by RT-PCR analysis. The expression of CfPGRP-S1 was upregulated initially in the first 12 h or 24 h either by M. lysodeikticus or V. anguillarum challenge and reached the maximum level at 24 h or 36 h, then dropped progressively, and recovered to the original level as the stimulation decreased at 72 h. There was no significant difference between V. anguillarum and M. lysodeikticus challenge. The results indicated that the CfPGRP-S1 was a constitutive and inducible acute-phase protein which was involved in the immune response against bacterial infection. (c) 2007 Elsevier Ltd. All rights reserved.
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The bay scallop Argopecten irradians is a hermaphroditic bivalve native to the Atlantic coast of the United States that was introduced to China for aquaculture production in 1982. It now supports a major aquaculture industry in China. Introduced species often start with limited genetic variability, which is problematic for the further selective breeding. Bay scallop aquaculture is exclusively hatchery based and as the initial introduction consisted of only 26 scallops, there have been concerns about inbreeding and inbreeding depression in cultured populations in China. In this study, eleven simple sequence repeat (SSR) markers were used to compare genetic variation in cultured populations from China with that in a natural population from the east coast of America. Although the difference in heterozygosity was small, the Chinese populations lost 9 of the 45 alleles (20%) found in the wild population. The reduced allele diversity suggests that the Chinese bay scallop populations experienced a bottleneck in genetic diversity that remains significant despite several recent introductions of new stocks aimed at expanding the gene pool. The loss of allele diversity may affect future efforts in selective breeding and domestication, and results of this study highlight the need for additional introductions, advanced breeding programs that minimize inbreeding and continued genetic monitoring. (c) 2007 Elsevier B.V. All rights reserved.