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1.
Mátyás Bognár 《Acta Mathematica Hungarica》2004,102(1-2):37-84
The following generalization of the Hahn-Mazurkiewicz theorem is proved: Let (E,e) be a locally compact locally connected metric space. Let M be a continuum in this space and let d,e∈ M. Then there is a continuous mapping f: [0,1]→E such that f(0) = d, f(1)= e and M⊂f([0,1]). Also some corollaries of this theorem are proved. 相似文献
2.
The aim of the paper is to investigate the limit behaviour of the least squares estimator of the shift parameter of nearly unstable, nearly stable, and nearly explosive AR(1) models. Both zero start and stationary cases are treated. Connection with the maximum likelihood estimator of the shift parameter of continuous time AR(1) processes is also discussed. 相似文献
3.
Nitrogen bridgehead compounds part 21. Preparation of new quaternary 2,3a,6a-triazaphenalenium salts
István Bitter Béla Pete István Hermecz Gábor Tóth Kálmán Simon Mátyás Czugler Zoltán Mészáros 《Tetrahedron letters》1982,23(28):2891-2894
The first representatives of a new ring system, the 2,3a,6a-triazaphenalenium quaternary salts are prepared by the cycloaddition of tetrahydro-4H-pyrido[1,2-a] pyrimidin-4-ones containing an α-chloroenamine moiety with azomethines. 相似文献
4.
Ingeborg Csöregh Mátyás Czugler Anne Ertan Edwin Weber Jochen Ahrendt 《Journal of inclusion phenomena and macrocyclic chemistry》1990,8(3):275-287
The crystal structures of four dimethyl sulphoxide (DMSO) inclusion compounds with different carboxylic acid hosts,1–4, have been studied by single crystal X-ray analysis. Crystals of thetrans-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic acid inclusion compound (1a), [1 · DMSO (1: 1)] show monoclinic (P21/n) symmetry with the unit cell dimensionsa = 11.522(4),b = 18.658(2),c = 8.709(1) Å and = 98.92(2)°. The clathrate of the 9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic acid (2a), [2 · DMSO (1: 2)] is triclinic (P) with the cell dimensionsa = 15.043(7),b =9.657(4),c = 8.118(7) Å, = 101.81(5), = 96.05(4) and = 100.04(4)°. Triclinic (P) symmetry is shown also by the inclusion compound of 9,10-dihydro-9,10-ethanoanthracene-11-monocarboxylic acid (3a) [3 · DMSO (1:1)] with the cell dimensionsa=6.3132(1),b=7.9846(2),c=17.5314(4) Å, = 96.46(2), = 87.08(2) and = 106.02(2)°. The 9,9-bianthryl-2-monocarboxylic acid clathrate (4a) [4 · DMSO (1:1)] is monoclinic (P21/n) and the cell dimensions area = 19.625(18),b = 8.817(1),c = 14.076(8) Å and = 97.92(6)°. In all these structures, the hosts show the same basic recognition pattern for the DMSO guest, involving a strong O-H ... O bond from the COON to the S=O group, and a possible C-H ... O type interaction between the carbonyl O atom of the host and a CH3 group of the guest. The crystals consist of discrete host-guest aggregates which are mainly held together by weak intermolecular interactions of the Van der Waals' type. The stoichiometries of the aggregates are, however, different. 相似文献
5.
H. Charcosset R. Fréty G. Leclercq B. Moraweck L. Tournayan J. Varloud 《Reaction Kinetics and Catalysis Letters》1979,10(4):301-306
Stable (Pt,Ir) solid solutions, 100 to 200 Å in particle size, were obtained although the corresponding bulk phases are not stable. Ir prevents the sintering of metal particles and alumina reduction to Al during heat treatment in H2. (Pt,Ir) alloys show an increase in hydrogenolysis, compared to Pt, during n-heptane conversion.
Pt Ir 100 200 Å, , . Ir Al H2. - Pt Ir Pt.相似文献
6.
Propylphosphonic anhydride (T3P®) was successfully applied to the synthesis of an isoindolinone library by the utilization of an Ugi four-center, three-component reaction (Ugi-4C-3CR). The use of T3P® significantly shortened the required reaction time and the corresponding products were obtained in good to high yields. Moreover, a side-reaction was observed when phenylethylamine derivatives and tryptamine were used as the amine component. The latter reaction was applied to the microwave-assisted, one-pot synthesis of the isoquinoline alkaloid (±)-nuevamine. Surprisingly, the traditional Ugi four-component reaction (Ugi-4CR) was unsuccessful in the presence of T3P®. In this case an α-amino amide was produced excluding the carboxylic acid from the multicomponent reaction. 相似文献
7.
Bekesová S Kovácik V Tvaroska I Curillová Z Skultéty L Rehulka P 《European journal of mass spectrometry (Chichester, England)》2007,13(2):147-154
Fragmentation mechanisms of phytoalexin analogs, including brassitin and brassinin and their glucosylated analogs, have been studied by electrospray (ESI) ion trap (IT) multistage (MS(n), n = 1-4) mass spectrometry, matrix-assisted laser desorption/ionization time-of-flight (MALDI ToF/ToF) and ESI-Q/ToF tandem mass spectrometry techniques. At the fragmentation of sodium adducts a hitherto not described process has been elucidated The proposed mechanism of this process includes cyclization of the brassitin and brassinin cationized adducts through a six-membered cycle of the molecules and the elimination of isocyanate or isothiocyanate from the thio- or dithiocarbamate moiety, giving rise to [M + Na - 43](+) or [M + Na - 59](+) adducts. The elimination of NH=C=O or NH=C=S molecules has been confirmed by the high resolution measurement of the elemental composition of the ions produced and quantum-chemical calculations of the six-membered transition state. Other fragmentation routes include cleavage of an alkane linker, while numerous characteristic hexopyranose pathways are taking place in the glucosylated compounds. The presented theoretical data on the ESI and MALDI behavior of the saccharidic, as well as of the indole aglycon parts, can facilitate structural elucidation of the analogous compounds. 相似文献
8.
Dénes Szabó István Kapovits Árpád Kucsman Mátyás Czugler Vilmos Fülöp Alajos Kálmán 《Structural chemistry》1991,2(5):529-535
1-[2-(N-methylcarbamoyl)phenyl]-3H-2,1-naphto-(1,8-d,e)-oxathiin-1-ium chloride (2), 1-[2-(N-methylcarbamoyl)-phenyl]-2-methyl-3-oxo-3H-1, 2-naphto-(1,8-d,e)-thiazin-1-ium chloride (3), 1-[8-(N-methylcarbamoyl)naphtyl]-2-methyl-3-oxo-3H-1, 2-naphto-(1,8-d,e)-thiazin-1-ium chloride (4) and 1-(8-carboxylatonaphtyl)-2-methyl-3-oxo-3H-1,2-naphto-(1,8-d,e)-thiazin-1-ium dipolar ion (5) cyclic sulfonium salts were prepared and their chemical properties investigated (spirosulfurane-formation, hydrolysis). The molecular structures obtained from x-ray diffraction can be described with a considerably distorted trigonal bipyramidal arrangement of the ligands about the sulfonium center, with O/N—S ... O=apical angles of 173.9, 164.9, 156.6, and 159.0°, as well as with S—O/N apical bond lengths of 1.648, 1.671, 1.664, and 1.682 Å. The structures exhibit relatively short S ... O close contacts with interatomic distances of 2.253, 2.448, 2.795, and 2.619 Å. 相似文献
9.
Mátyás Milen László Hazai Pál Kolonits György Kalaus Lajos Szabó Ágnes Gömöry Csaba Szántay 《Central European Journal of Chemistry》2005,3(1):118-136
Transformation of β-carboline derivatives into optically active entities were studied and the de and ee values of the resulted compounds were detected.
Dedicated to Professor Károly Lempert on his 80th birthday. 相似文献
10.
Ferenc Faigl Ervin Kovács Dóra Balogh Tamás Holczbauer Mátyás Czugler Béla Simándi 《Central European Journal of Chemistry》2014,12(1):25-32
The first enzyme-catalyzed kinetic resolution of tert-butyl-3-hydroxy-4-phenylpyrrolidine-1-carboxylate is presented. Enzyme, solvent and temperature optimization resulted in a new resolution method with E = 40 enantioselectivity. The acetate derivative of the (+)-(3S,4R) enantiomer formed while the (?)-(3R,4S) isomer remained intact. Very good enantioselectivities (E > 200) were achieved in the enzyme-catalyzed alcoholysis of the racemic acetate in i-propanol and t-butanol where the (+)-(3S,4R) enantiomer was prepared in pure form (ee > 99.7%). Absolute configuration of the (?)-(3R,4S)-enantiomer was determined by single crystal X-ray diffraction method. 相似文献