关于丢番图方程P2z-PzDm+D2m=X2(I)

设P为素数,P鄹D>1,完全解决丢番图方程A:P2z-PzDm D2=X2。得到如下结论:(Ⅰ)若P=2,则方程(A)除D=3仅有非负整数解26-23·3 32=72和D=3·22k-4 2k-1-1(k≥3)仅有非负整数解22k-2k·(3·22k-4 2k-1-1) (3·22k-4 2k-1-1)2=(3·22k-4 1)2以及D=22k-4 2k-1-3(k≥3)仅有非负整数解22k-2k·(22k-4 2k-1-3) (22k-4 2k-1-3)2=(22k-4 3)2之外,无其他非负整数解。(Ⅱ)若P=3,则方程(A)除D=32k 1 2·3k-14(k≥1)仅有非负整数解32k-3k·32k 1 2·3k-14 (32k 1 2·3k-14)2=32k 1 14 2之外,无其他非负整数解。(Ⅲ)若P>3为奇素数熏则方程(A)除D=3P2k 2Pk-34(k≥1)仅有非负整数解P2k-Pk·P2k 2Pk-34 (P2k 2Pk-34)2=3P2k 14 2和D=P2k 2Pk-34(k≥1)仅有非负整数解P2k-Pk·P2k 2Pk-3 (P2k 2Pk-3)2=P2k 3 2之外,无其他非负整数解。     

Long-range incommensurate charge fluctuations in (Y,Nd)Ba2Cu3O(6+x)

The concept that superconductivity competes with other orders in cuprate superconductors has become increasingly apparent, but obtaining direct evidence with bulk-sensitive probes is challenging. We have used resonant soft x-ray scattering to identify two-dimensional charge fluctuations with an incommensurate periodicity of ~3.2 lattice units in the copper-oxide planes of the superconductors (Y,Nd)Ba(2)Cu(3)O(6+)(x), with hole concentrations of 0.09 to 0.13 per planar Cu ion. The intensity and correlation length of the fluctuation signal increase strongly upon cooling down to the superconducting transition temperature (T(c)); further cooling below T(c) abruptly reverses the divergence of the charge correlations. In combination with earlier observations of a large gap in the spin excitation spectrum, these data indicate an incipient charge density wave instability that competes with superconductivity.     

A Quantum State-Resolved Insertion Reaction: O((1)D) + H(2)(J = 0) --> OH((2) product operator product operator product operator, v, N) + H((2)S)

The O((1)D) + H(2) --> OH + H reaction, which proceeds mainly as an insertion reaction at a collisional energy of 1.3 kilocalories per mole, has been investigated with the high-resolution H atom Rydberg "tagging" time-of-flight technique and the quasiclassical trajectory (QCT) method. Quantum state-resolved differential cross sections were measured for this prototype reaction. Different rotationally-vibrationally excited OH products have markedly different angular distributions, whereas the total reaction products are roughly forward and backward symmetric. Theoretical results obtained from QCT calculations indicate that this reaction is dominated by the insertion mechanism, with a small contribution from the collinear abstraction mechanism through quantum tunneling.     

Ordering of V2+, Mn2+, and Fe3+ Ions in Zoisite, Ca2Al3Si3O12(OH)

The presence of very small amounts of Mn(2+), V(2+), and Fe(3+) ions in zoisite can be easily detected by the electron paramagnetic resonance technique at room temperature. The Mn(2+) and Fe(3+) ions are completely ordered and are probably located in the Ca(1)- and Al(II)-sites, respectively, whereas the V(2+) ions probably occupy both Ca(1)- and Ca(2)-sites, with a preference for the Ca(1)-site.     

Identification,Characterization, and Expression of P450 Gene Encoding CYP6BQ13v2 from the Red Flour Beetle,Tribolium castaneum （Herbst） （Coleoptera： Tenebrionidae）

An allele of CYP6BQI3, named CYP6BQ 13v2 （GenBank accession no. FJ209361）, was isolated from the red flour beetle, Tribolium castaneum （Herbst） （Coleoptera： Tenebrionidae） by RT-PCR. The cDNA sequence of CYP6BQ13v2, 1 563 bp in length, contains an open reading frame of 1 554 nucleotides encoding a putative protein of 518 amino acid residues with a predicted molecular weight of 59.92 kDa and a theoretical pl of 7.60. The putative protein contains the classic hemebinding sequence motif F××G×××C×G （residues 456-465） conserved among all P450 enzymes as well as other characteristic motifs of all cytochrome P450s. It shares 98% identity with the previously published sequence of CYP6BQ13 （GenBank accession no. XP967146） from the T. castaneum genome project. Phylogenetic analysis of amino acid sequences from members of various P450 families indicated that there was closer phylogenetic relationship of CYP6BQ 13v2 with CYP302A1 and CYP307A1 mediating synthesis of the insect molting hormone, distant relationship with CYP6B1 metabolizing plant allelochemicals, CYP6D 1 linking to pyrethroid resistance and other members of CYP6 family. Expression test of the gene in the adults and immature stages of T. castaneum by quantitative real-time PCR revealed that CYP6BQ13v2 is expressed in all life stages investigated. The mRNA expression level in 1st instar larvae was 14.9- and 3.86-fold higher than those in pupae and adults, respectively. The CYP6BQ13v2 expression levels appeared in the order of 1st instar larvae, followed by 4th instar larvae, 7th instar larvae, adult, and pupae from high to low. The more bioinformation of CYP6BQ 13v2 was also analyzed.     

State-to-State Rates for the D + H2(v = 1, j = 1) rarr HD(v', j') + H Reaction: Predictions and Measurements

A fully quantal wavepacket approach to reactive scattering in which the best available H(3) potential energy surface was used enabled a comparison with experimentally determined rates for the D + H(2)(v = 1, j = 1) --> HD(v' = 0, 1, 2; j') + H reaction at significantly higher total energies (1.4 to 2.25 electron volts) than previously possible. The theoretical results are obtained over a sufficient range of conditions that a detailed simulation of the experiment was possible, thus making this a definitive comparison of experiment and theory. Good to excellent agreement is found for the vibrational branching ratios and for the rotational distributions within each product vibrational level. However, the calculated rotational distributions are slightly hotter than the experimentally measured ones. This small discrepancy is more marked for products for which a larger fraction of the total energy appears in translation. The most likely explanation for this behavior is that refinements are needed in the potential energy surface.     

The spin excitation spectrum in superconducting YBa(2)Cu(3)O(6.85)

A comprehensive inelastic neutron scattering study of magnetic excitations in the near optimally doped high-temperature superconductor YBa(2)Cu(3)O(6.85) is presented. The spin correlations in the normal state are commensurate with the crystal lattice, and the intensity is peaked around the wave vector characterizing the antiferromagnetic state of the insulating precursor, YBa(2)Cu(3)O(6). Profound modifications of the spin excitation spectrum appear abruptly below the superconducting transition temperature T(c), where a commensurate resonant mode and a set of weaker incommensurate peaks develop. The data are consistent with models that are based on an underlying two-dimensional Fermi surface, predicting a continuous, downward dispersion relation connecting the resonant mode and the incommensurate excitations. The magnetic incommensurability in the YBa(2)Cu(3)O(6+)(x) system is thus not simply related to that of another high-temperature superconductor, La(2-)(x)Sr(x)CuO(4), where incommensurate peaks persist well above T(c). The temperature-dependent incommensurability is difficult to reconcile with interpretations based on charge stripe formation in YBa(2)Cu(3)O(6+x) near optimum doping.     

烤烟套种甘薯对烟草氮磷钾营养的影响

通过田间小区试验,研究了烤烟与甘薯套种对烟草氮磷钾素营养的影响.结果表明:烤烟套种甘薯与烤烟单作相比,甘薯吸收了土壤中过多残留的营养元素,土壤营养元素更趋于平衡;增加了土壤耕层中植株的根系,其周围营养元素有效性得以提高,相对含量增加,烟株与环境友好发展,烟株养分得以改善;对烤烟的茎粗、叶厚、株高、叶长、叶宽、有效叶片数等生物学性状未产生不良影响.     

O,O-二烷基-N-莰-2-基(硫)磷酰胺酯的合成

合成了14个含有 N-莰-2-基的磷酰胺和硫代磷酰胺类化合物,用红外、核磁及元素分析确定其结构,并探讨了~(31)Pδ值的规律性变化。初步生物试验表明,磷酰胺类化合物对水稻发芽具有明显的抑制作用,其中化合物Ⅱ1的活性大于对照药剂抗倒胺但低于多效唑。     

An Inorganic Double Helix: Hydrothermal Synthesis, Structure, and Magnetism of Chiral [(CH3)2NH2]K4[V10O10(H2O)2(OH)4(PO4)7]{middle dot}4H2O

Very complicated inorganic solids can be self-assembled from structurally simple precursors as illustrated by the hydrothermal synthesis of the vanadium phosphate, [(CH(3))(2)NH(2)]K(4)[V(10)O(10)(H(2)O)(2)(OH)(4)(PO(4))(7)].4H(2)O, 1, which contains chiral double helices formed from interpenetrating spirals of vanadium oxo pentamers bonded together by P(5+). These double helices are in turn intertwined with each other in a manner that generates unusual tunnels and cavities that are filled with (CH(3))(2)NH(2)(+) and K(+) cations, respectively. The unit cell contents of dark blue phosphate 1, which crystallizes in the enantiomorphic space group P4(3) with lattice constants a = 12.130 and c = 30.555 angstroms, are chiral; only one enantiomorph is present in a given crystal. Magnetization measurements show that 1 is paramagnetic with ten unpaired electrons per formula unit at higher temperatures and that antiferromagnetic interactions develop at lower temperatures.     

O2 activation by nonheme iron complexes: A monomeric Fe(III)-Oxo complex derived from O2

Iron species with terminal oxo ligands are implicated as key intermediates in several synthetic and biochemical catalytic cycles. However, there is a dearth of structural information regarding these types of complexes because their instability has precluded isolation under ambient conditions. The isolation and structural characterization of an iron(III) complex with a terminal oxo ligand, derived directly from dioxygen (O2), is reported. A stable structure resulted from placing the oxoiron unit within a synthetic cavity lined with hydrogen-bonding groups. The cavity creates a microenvironment around the iron center that aids in regulating O2 activation and stabilizing the oxoiron unit. These cavities share properties with the active sites of metalloproteins, where function is correlated strongly with site structure.     

Crystal Structure of Kernite, Na2B4O6(OH)2 {middle dot} 3H2

Kernite, Na(2)B(4)O(6)(OH)(2). .3H(2)0, contains parallel infinite chains of the borate polyanion[B(4)O(6)(OH)(2)](n)(2n-). The chains are composed of six-membered rings containing one boron-oxygen triangle and two boron-oxygen tetrahedra. The rings are linked through commonly shared boron-oxygen tetrahedra.     

Open Framework Structures Based on Sex2- Fragments: Synthesis of (Ph4P)[M(Se6)2] (M = Ga, In, TI) in Molten (Ph4P)2Sex

Polychalcogenide compounds with open polymeric frameworks are rare, and they represent a class of compounds in which microporosity might be achieved. Microporous frameworks that are not oxide-based are now attracting interest because of the combination of catalytic and electronic properties they may simultaneously possess. Three new compounds that may be forerunners to such materials have been discovered and are reported here. The reaction of gallium (Ga), indium (In), and thallium (TI) metal with (Ph(4)P)(2)Se(5) (Ph, phenyl) and an excess of elemental selenium (Se) in a sealed, evacuated Pyrex tube at 200 degrees C yielded small red crystals of (Ph(4)P)[Ga(Se(6))(2)] (I), (Ph(4)P)[In(Se(6))(2)] (II), and (Ph(4)P)[TI(Se(6))(2)] (III), respectively. The [M(Se(6))(2)](-) (M = Ga, In, TI) ions form a two-dimensional, open framework filled with Ph(4)P(+) ions. The [M(Se(6))(2)](n)(n-) structure consists of tetrahedral M(3+) centers and bridging Se(6)(2-) ligands, leading to an extended structure in two dimensions. These layers stack perfectly one on top of the other giving rise to one-dimensional channels running down the c axis that are filled with Ph(4)P(+) cations. These cations are situated in the layers, as opposed to between the layers, and the whole structure can be viewed as a template. Compound II shows remarkable thermal stability and melts congruently at 242 degrees C. Upon cooling to room temperature it gives a glassy phase that recrystallizes upon subsequent heating to 160 degrees C.     

Bulk Superconductivity at 122 K in T1(Ba,Ca)2Ca3Cu4O10.5+8 with Four Consecutive Copper Layers

The observed increase of superconducting transition temperature (T(c)) with the number of copper oxide planes continues in the four-[CuO(2)](-2) layer (single TI layer) oxide superconductor, which has been prepared with > 80% purity and was magnetically aligned for crystallographic identification. A master scaling curve is proposed, which ties together the T(c)'s of virtually all known Bi and Tl oxide superconductors, and shows that the Tl(Bi) layers play an essential role in the superconductivity. publication 350 of the Barnett Institute.     

Ni(NO3)2对汕优13水稻幼苗中过氧化氢酶活性的影响

在水稻幼苗2.5叶期，分别用浓度W/V0.01%,0.03%和0.04%(Ni(NO3)2溶液（含0.05%Tween20聚环氧乙烷山梨糖醇单月桂酸酯）喷雾处理，以0.5%(W/V)Tween20作对照，在4小时，24小时，48小时，72小时，96小时分别测定叶片中的过氧化氢酶（CAT）活性，结果表明，Ni(NO3)2对过氧化氢酶活性有抑制作用且随其浓度的升高，抑制作用越明显，在72小时抑制作用最强，过氧化氢酶活性比对照分析下降了21.7%,28.3%,55.8%。     

Laminar growth of ultrathin metal films on metal oxides: Co on hydroxylated alpha-Al2O3(0001)

Metals deposited in vacuum on metal oxides such as alumina normally grow as three-dimensional clusters because of weak adatom-substrate interactions. This tendency hinders our ability to form interfaces of ultrathin, laminar metal films on oxides for use in microelectronics and other technologies where nanostructural control is desired. We present experimental and theoretical results showing that room temperature Co deposition on fully hydroxylated clean sapphire (alpha-Al2O3) produces a surface chemical reaction that leads to laminar growth, despite a large mismatch in lattice constants. This process should be applicable to a wide range of metals and metal oxides.     

Dynamics of Carbonium Ions Solvated by Molecular Hydrogen: CH5+(H2)n (n = 1, 2, 3)

The dynamics of the carbonium ion (CH(5)(+)), a highly reactive intermediate with no equilibrium structure, was studied by measuring the infrared spectra for internally cold CH(5)(+)(H(2))n(n = 1, 2, 3) stored in an ion trap. First-principle molecular dynamics methods were used to directly simulate the internal motion for these ionic complexes. The combined experimental and theoretical efforts substantiated the anticipated scrambling motion in the CH(5)(+) core and revealed the effect of the solvent molecular hydrogen in slowing down the scrambling. The results indicate the feasibility of using solvent molecules to stabilize the floppy CH(5)(+) ion in order to make it amenable to spectroscopic study.     

Cytokinin from soluble RNA of Escherichia coli: 6-(3-methyl-2-butenylamino)-2-methylthio-9-beta-D-ribofuranosylpurine

We have isolated a compound responsible for the cytokinin activity of soluble RNA from Escherichia coli. The structure, indicated as 6-(3-methyl-2-butenylamino)-2-methylthio-9-beta-D-ribofuranosylpurine, C(16)H(23)N(5)0(4)S, on the basis of low-and high-reso!ution mass spectrometry, was established by unequivocal synthesis. The mass spectra, chromatographic behavior, and ultraviolet spectra of the compounds from natural and synthetic sources were identical.     

Gd在Ba_2RCu_3O(7+δ)(R=Y,HO)高温超导体表面上引起的化学反应

本文利用X射线光电子谱(XPS)对Gd原子在Ba_2RCu_3O_(7+8)(R=Y, Ho)高温超导体表面上引起的化学反应进行了研究.实验发现,在该超导样品表面上蒸镀的Gd原子被氧化,超导体中对超导特性起重要作的Cu-O链遭到破坏,其中一部分处于Cu~(2+)态的Cu元素被还原,超导体内其它各元素也不同程度地受到了影响.当样品表面上Gd覆盖度达到22A(R=Y)和30A(R=Ho)时,界面上的化学反应不再继续