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71.
Wahyudi Aris Tri Takeyama Haruko Matsunaga Tadashi 《Applied biochemistry and biotechnology》2001,91(1-9):147-154
Nonmagnetic mutants of Magnetospirillum magneticum AMB-1 were recovered following mini-Tn5 transposon mutagenesis. Transconjugants with kanamycin resistance were obtained at
a frequency of 2.7 × 10−7 per recipient. Of 3327 transconjugants, 62 were defective for bacterial magnetic particle (BMP) synthesis. The frequency
of independent transposition events for nonmagnetic mutants was about 1.4% in transconju gants. Further analysis of DNA sequences
flanking transposon by inverted polymerase chain reaction allowed isolation of at least 10 genes or DNA sequences involved
in BMP synthesis in M. magneticum AMB-1. 相似文献
72.
The reaction of succinamic acid (H2sucm) with Ca(NO3)2·4H2O yielded compounds [Ca(Hsucm)(NO3)(H2O)]n (1) and [Ca(Hsucm)2]n (2). The succinamate(-1) ligand presents two new ligation modes and coordinates through the two carboxylato and the amide O-atoms, thus bridging three CaII ions which assemble into zig-zag 1D chains in 1 and 2D networks in 2. Intermolecular hydrogen bonding interactions in the crystal structures of 1 and 2 result in overall 3D framework structures. Both compounds have been characterized by IR and 1H NMR spectroscopy, and their thermal decomposition was monitored by TG/DTG and DSC measurements. The structural comparison of 1 and 2 with known lanthanide(III) succinamate(-1) complexes reveals differences in the coordination mode of the ligand and in the coordination number of the metal ions; the biological relevance of these differences is discussed. 相似文献
73.
Papaefstathiou GS Manessi A Raptopoulou CP Terzis A Zafiropoulos TF 《Inorganic chemistry》2006,45(22):8823-8825
Treatment of a methanolic solution of gallium(III) nitrate with lithium hydroxide in the presence of benzilic acid resulted in the decanuclear cluster [Ga(OMe)2{O2CC(OH)Ph2}]10 (1). The metal and the organic components have assembled to form a cyclic molecule that adopts the structure of a wheel. The 10 Ga(III) ions are approximately coplanar and are coordinated in a distorted octahedral manner by six oxygen atoms. The integrity of the molecular wheel is retained in solution, as evidenced by the 1NMR spectrum of 1 in DMSO-d6, while no signal in the 71Ga NMR could be detected. 相似文献
74.
In a quantum dot with three leads, the transmission matrix t12 between two of these leads is a truncation of a unitary scattering matrix S, which we treat as random. As the number of channels in the third lead is increased, the constraints from the symmetry of S become less stringent and t12 becomes closer to a matrix of complex Gaussian random numbers with no constraints. We consider the distribution of the singular values of t12, which is related to a number of physical quantities. 相似文献
75.
Replacement of NH3 by a planar amine L to give trans-[PtCl2(L)(L')] (L = NH3, L'= pyridine or substituted pyridine, quinoline, isoquinoline, thiazole; L = L'= pyridine, thiazole), greatly enhances the cytotoxicity of the transplatinum geometry. The "parent" compound trans-[PtCl2(NH3)2] is therapeutically inactive. Modification of the ligands to an [N2O2] donor set, where O represents an acetate leaving group, enhances the aqueous solubility while retaining the cytotoxicity of the parent chloride compounds. The effect of two mutual trans leaving groups with weak trans influence is to impart remarkable chemical stability on the structure. This strategy is analogous to the use of the inert dicarboxylate leaving groups in the clinical compounds carboplatin and oxaliplatin. In this paper, systematic modification of the steric effects of carrier pyridine groups and, especially, carboxylate leaving groups in trans-[Pt(O2CR)2(NH3)(pyr)] is shown to modulate aqueous solubility and hydrolysis to the activated aqua species. The results presented here demonstrate the utility of the "carboxylate strategy" in "fine-tuning" the chemical and pharmacokinetic properties in the design of clinically relevant transplatinum complexes. 相似文献
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78.
Jérôme Bolte Aris Daniilidis Adrian Lewis 《Journal of Mathematical Analysis and Applications》2006,321(2):729-740
According to the Morse-Sard theorem, any sufficiently smooth function on a Euclidean space remains constant along any arc of critical points. We prove here a theorem of Morse-Sard type suitable as a tool in variational analysis: we broaden the definition of a critical point to the standard notion in nonsmooth optimization, while we restrict the functions under consideration to be semialgebraic or subanalytic. We make no assumption of subdifferential regularity. ?ojasiewicz-type inequalities for nonsmooth functions follow quickly from tools of the kind we develop, leading to convergence theory for subgradient dynamical systems. 相似文献
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