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排序方式: 共有248条查询结果,搜索用时 15 毫秒
221.
Preparation of 1-methylpyrrole-2-acetonitrile, 1-methyl-5-(4-methylbenzoyl) pyrrole-2-acetonitrile and 2-(6-methoxy-2-naphthyl)propionitrile by treatment of 1-methylpyrrole-2-carboxaldehyde, 1-methyl-5-(4-methylbenzoyl)pyrrole-2-carboxaldehyde and, respectively, 6-methoxy-2-acetylnaphthalene with tosylmethylisocyanide (TosMIC) is described. This one-step synthetic procedure is very useful to obtain the nitrile precursors of tolmetin and naproxen, two clinically important non-steroidal antiinflammatory agents (NSAIAs). 相似文献
222.
R. Albrecht T. C. Awes C. Baktash P. Beckmann F. Berger R. Bock G. Classon L. Dragon R. L. Ferguson A. Franz S. Garpman R. Glasow H. A. Gustafsson H. H. Gutbrod K. H. Kampert B. W. Kolb P. Pristiansson I. Y. Lee H. L?hner I. Lund F. E. Obenshain A. Oskarsson I. Ottrlund T. Peitzmann S. Persson F. Plasil A. M. Poskanzer M. Purschke H. G. Ritter R. Santo H. R. Schmidt T. Siemiarczuk S. P. Sorensen E. Stenlung G. R. Young WA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1988,38(1):97-103
Transverse momentum (p T) distributions fo inclusive photons and neutral pions at midrapidity are measured with a lead glass calorimeter in 60 and are measured with a lead glass calorimeter in 60 and 200A·Gev16O+nucleus and and proton+nucleus reactions. Inclusive photon distributions are compared for central and peripheral reactions. The degree of centrality is determined either from the charged particle multiplicity or from the remaining projectile energy in the forward direction. Deviations from a nucleus+nucleus interaction model based upon linear extrapolation from p+p reactions are observed in central16O+Au data. The variation of theaverage transverse momentum is investigated as function of centrality. The target-mass and energy dependence of π0 p T distributions are presented. For16O+Au a change of slope in these distributions is observed atp t ≈0.8 GeV/c compatible with hydrodynamic expansion models. 相似文献
223.
Santo M Cattana R Silber JJ 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2001,57(8):1541-1553
Solvatochromic studies on quinoline (Q), 3-cyanoquinoline (CNQ), 3-bromoquinoline (BrQ) and 8-hydroxyquinoline (OHQ) in pure solvents and alcohol-cyclohexane mixtures have been performed. The results are compared with Proton Nuclear Magnetic Resonance, 1H NMR. studies and AMI calculations. Taft and Kamlet's solvatochromic comparison method was used to disclose solvent effects in pure solvents. These studies shows that the hydrogen bond acceptor ability of the Q ring is diminished and its polarity is increased by the presence of the cyano group in CNQ and the bromo group in BrQ. In OHQ, intramolecular hydrogen bonding has been observed. This interaction is weakened by the interaction with protic solvents. The studies in binary mixtures, alcohol-cyclohexane, show solute-solvent interactions, which compete with solvent self-association in the preferential solvation phenomena. Alcohols with strong ability to self-associate have less preference toward solvation of these compounds. The association constants for solute-ethanol systems were determined by 1H NMR. The results show that the solvent hydrogen bond donor ability is the main factor involved in the interaction with these solutes at the aza aromatic site. 相似文献
224.
225.
New pyridylthioether-based dendrons bearing a thiol moiety at their focal point have been prepared by a convergent synthetic approach. These dendrons were readily attached to a Fe2(CO)6 core to generate two-directional dendritic molecules incorporating an iron-carbonyl cluster. 相似文献
226.
Miyamoto R Santo R Matsushita T Nishioka T Ichimura A Teki Y Kinoshita I 《Dalton transactions (Cambridge, England : 2003)》2005,(19):3179-3186
A complete series of copper(ii) halide complexes [CuX(tptm)](X = F (), Cl (), Br (), I (); tptm = tris(2-pyridylthio)methyl) with a novel Cu(II)-C(sp(3)) bond has been prepared by the reactions of [Cu(tptm)(CH(3)CN)]PF(6)(.PF(6)) with corresponding halide sources of KF or n-Bu(4)NX (X = Cl, Br, I), and the trigonal bipyramidal structures have been confirmed by X-ray crystallography and/or EPR spectroscopy. The iodide complex easily liberates the iodide anion in acetonitrile forming the acetonitrile complex as a result. The EPR spectra of the complexes showed several superhyperfine structures that strongly indicated the presence of spin density on the halide ligands through the Cu-X bond. The results of DFT calculations essentially matched with the X-ray crystallographic and the EPR spectroscopic results. Cyclic voltammetry revealed a quasi-reversible reduction wave for Cu(II)/Cu(I) indicating a trigonal pyramidal coordination for Cu(I) states. A coincidence of the redox potential for all [CuX(tptm)](0/+) processes indicates that the main oxidation site in each complex is the tptm ligand. 相似文献
227.
Venema LB Braak H Löhner H Raschke AE Siemssen RH Sumbera M Wilschut HW Berg F Kühn W Metag V Notheisen M Novotny R Pfeiffer M Ritman J Schwalb O Gobbi A Hildenbrand KD Hlavác S Holzmann R Simon RS Sodan U Teh K Wessels JP Herrmann N Wienold T Kotte R Mösner J Neubert W Wohlfarth D Ostendorf R Schutz Y Brummund N Santo R 《Physical review letters》1993,71(6):835-838
228.
229.
M.S.F. Lima R. Riva M.G. Destro A.M.E. Santo R.A. Silva Jr. S.M. Guimaraes 《Optics & Laser Technology》2009,41(2):159-164
Electrical cable-connector sets used in airplanes have been laser soldered using a lead-free paste. These connections are usually crimped using a hand tool, which necessarily leads to variable mechanical and electrical properties in the connection. Calorimetric studies have shown that paste melting occurs within tenths of a second at laser intensities of 400 or 500 W cm−2. However, when such laser intensities strike the connector surface, some boiling occurs. In order to avoid paste losses, a stepped heating curve is applied, which allows good weldability. It was verified that a reaction layer of 2 μm length exists between the wires and the solidified solder paste, and also that there is some diffusion of copper from the wires to the paste. The soldered joints are 38% more electrically conductible and have 113% more tensile strength resistance than crimped joints. 相似文献
230.
Alzogaray RA Fontán A Camps F Masuh H Santo Orihuela P Fernández D Cork A Zerba E 《Molecules (Basel, Switzerland)》2005,10(9):1190-1196
The behavioural responses of the haematophagous bug Triatoma infestans towards some previously identified components of its faeces: 4-methylquinazoline, 2,4- dimethylquinazoline and their mixtures were evaluated using a video tracking system. Fifth instar nymphs and females but not males were significantly attracted to polyethylene glycol formulations of 4-methyl + 2,4-dimethylquinazoline (50 microg each). Fifth instar nymphs were also attracted to 4-methylquinazoline alone (50 microg) but females were only attracted by the mixture of both methyl quinazolines (50 microg each). Syntheses of both methyl quinazolines were carried out starting from 2-aminoacetophenone by modifying the conditions of reported procedures. 相似文献