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901.
902.
A general approach to isosteric phosphonate analogues of ulose-l-phosphates is described. A base-catalysed chain elongation via a Michael addition of 1-deoxy-1-nitro-sugars 4, 8 , and 16 to the vinylphosphonate 18 followed by hydrolysis of the nitro adducts gave the analogues of D -ribulose-1-phosphate, D -fructose-1-phosphate, and D -sedoheptulose-1,7-diphosphate 21, 23 , and 27 , respectively, in high yields. 相似文献
903.
Harald Hagendorfer Christiane Lorenz Ralf Kaegi Brian Sinnet Robert Gehrig Natalie V. Goetz Martin Scheringer Christian Ludwig Andrea Ulrich 《Journal of nanoparticle research》2010,12(7):2481-2494
This study describes methods developed for reliable quantification of size- and element-specific release of engineered nanoparticles
(ENP) from consumer spray products. A modified glove box setup was designed to allow controlled spray experiments in a particle-minimized
environment. Time dependence of the particle size distribution in a size range of 10–500 nm and ENP release rates were studied
using a scanning mobility particle sizer (SMPS). In parallel, the aerosol was transferred to a size-calibrated electrostatic
TEM sampler. The deposited particles were investigated using electron microscopy techniques in combination with image processing
software. This approach enables the chemical and morphological characterization as well as quantification of released nanoparticles
from a spray product. The differentiation of solid ENP from the released nano-sized droplets was achieved by applying a thermo-desorbing
unit. After optimization, the setup was applied to investigate different spray situations using both pump and gas propellant
spray dispensers for a commercially available water-based nano-silver spray. The pump spray situation showed no measurable
nanoparticle release, whereas in the case of the gas spray, a significant release was observed. From the results it can be
assumed that the homogeneously distributed ENP from the original dispersion grow in size and change morphology during and
after the spray process but still exist as nanometer particles of size <100 nm. Furthermore, it seems that the release of
ENP correlates with the generated aerosol droplet size distribution produced by the spray vessel type used. This is the first
study presenting results concerning the release of ENP from spray products. 相似文献
904.
Peter?Schwenkreis Andrea?Scherens Anne-Kathrin?R?nnau Oliver?H?ffken Martin?Tegenthoff Christoph?Maier 《BMC neuroscience》2010,11(1):73
Background
The aim of this study was to examine the relationship between chronic neuropathic pain after incomplete peripheral nerve lesion, chronic nociceptive pain due to osteoarthritis, and the excitability of the motor cortex assessed by transcranial magnetic stimulation (TMS). Hence in 26 patients with neuropathic pain resulting from an isolated incomplete lesion of the median or ulnar nerve (neuralgia), 20 patients with painful osteoarthritis of the hand, and 14 healthy control subjects, the excitability of the motor cortex was tested using paired-pulse TMS to assess intracortical inhibition and facilitation. These excitability parameters were compared between groups, and the relationship between excitability parameters and clinical parameters was examined. 相似文献905.
Highly proficient German users of English as a second language, and native speakers of American English, listened to nonsense sequences and responded whenever they detected an embedded English word. The responses of both groups were equivalently facilitated by preceding context that both by English and by German phonotactic constraints forced a boundary at word onset (e.g., lecture was easier to detect in moinlecture than in gorklecture, and wish in yarlwish than in plookwish). The American L1 speakers' responses were strongly facilitated, and the German listeners' responses almost as strongly facilitated, by contexts that forced a boundary in English but not in German (thrarshlecture, glarshwish). The German listeners' responses were significantly facilitated also by contexts that forced a boundary in German but not in English (moycelecture, loitwish), while L1 listeners were sensitive to acoustic boundary cues in these materials but not to the phonotactic sequences. The pattern of results suggests that proficient L2 listeners can acquire the phonotactic probabilities of an L2 and use them to good effect in segmenting continuous speech, but at the same time they may not be able to prevent interference from L1 constraints in their L2 listening. 相似文献
906.
Biver T Lombardi D Secco F Tiné MR Venturini M Bencini A Bianchi A Valtancoli B 《Dalton transactions (Cambridge, England : 2003)》2006,(12):1524-1533
The macrocyclic polyamine 2,5,8,11,14-pentaaza[15]-[15](2,9)[1,10]phenanthrolinophane (neotetren) is studied in its ability to coordinate Cu(ii) even at very low pH values and to interact, as a metal complex, with DNA. The kinetics and equilibria for 1 : 1 and 2 : 1 metal-ligand complexes formation are studied by the stopped-flow method and UV spectrophotometry. Differently protonated complexes are formed, with rate constants much lower than that of water exchange at copper(II) and other Cu(II)/amine systems, this behaviour being ascribed to ring effects and intra-molecular hydrogen bonds. Concerning the DNA/copper(II)-neotetren complexes interaction, analysis of data suggests an intercalative mode of binding. The kinetic results for both DNA/CuL and DNA/Cu(2)L systems agree with the sequence D + S <-->D,S <-->DS where the metal complexes (D) react with the DNA sites (S) leading to fast formation of an externally bound form (D,S) which is converted into an intercalated complex (DS). A very slow process is also detected and ascribed to a conformational change in the polynucleotide secondary structure where the metal centre plays a crucial role. Chromatographic experiments demonstrate that both the investigated Cu(II)/L complexes are able to cleave DNA, but only in the presence of hydrogen peroxide. 相似文献
907.
Bencini A Beni A Costantino F Dei A Gatteschi D Sorace L 《Dalton transactions (Cambridge, England : 2003)》2006,(5):722-729
[Co(Me(4)cyclam)(tropolonate)](PF(6)) was synthesised and structurally characterised. Its electronic and W-band EPR spectra have been analysed by means of the angular overlap calculation of the Spin Hamiltonian parameters that provided also a satisfactory reproduction of the temperature dependence of the magnetic susceptibility. The present results can be interpreted assuming a pseudo-octahedral character for the Co(II) center. This prompted us to reconsider the model formerly used for the analysis of the magnetic coupling between hs-Co(II) and the paramagnetic o-semiquinonate ligand in the corresponding derivatives [Co(Me(4)cyclam)(PhenSQ)](PF(6)) and [Co(Me(4)cyclam)(DTBSQ)](PF(6)). These results indicate that the effect of the magnetic coupling is active only below 50 K and that a more refined model of exchange coupling between Co(II) and semiquinonato ligands is needed to quantitatively analyze the magnetic behaviour of this class of systems. 相似文献
908.
Chen CL Ellsworth JM Goforth AM Smith MD Su CY Zur Loye HC 《Dalton transactions (Cambridge, England : 2003)》2006,(44):5278-5286
The first monocarboxylate-substituted 4,4'-bipyridine ligand, 4,4'-bipyridine-2-carboxylic acid (4-(pyridin-4-yl)pyridine-2-carboxylic acid (PPCAH)), has been successfully synthesized from 4,4'-bipyridine. Reactions with transition metals zinc and manganese were used to establish the coordination characteristics of the product, 4,4'-bipyridine-2-carboxylic acid, and of the synthetic intermediate, 2-methyl-4,4'-bipyridine, by single-crystal X-ray diffraction. The ligand PPCAH is useful for the formation of metal-containing building blocks that can be used in the assembly of mixed-metal framework materials. The synthesis and structure of one such mixed-metal coordination polymer, Cu(PPCA)(2)HgI(2), is also presented. 相似文献
909.
We give some upper bounds on the dimension of the kernel of the cup product map $H^{1}(X,\mathbb{C}) \otimes H^{1}(X,\mathbb{C}) \to H^{2}(X,\mathbb{C})We give some upper bounds on the dimension of the kernel of the cup product map
, where X is a compact K?hler variety without Albanese fibrations. 相似文献
910.