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R. Pizzoferrato L. Lagonigro T. Ziller A. Di Carlo R. Paolesse F. Mandoj A. Ricci C. Lo Sterzo 《Chemical physics》2004,300(1-3):217-225
We study the infrared emission at 1.54 μm of an organolanthanide complex, Er(III)-tetraphenylporphyrin [Er(TPP)acac], both as a result of direct optical excitation and via energy transfer from host π-conjugate polymers of type poly(arylene–ethynylene) [PAE]. In the first case, the emission of the neat complex is characterized in inert transparent materials and a value of the quantum yield at 1.54 μm φIR=4×10−4 is measured. Then, fluorescence resonance transfer is investigated in blends of Er(TPP)acac with PAEs by monitoring the quenching of the polymer fluorescence along with the enhancement of both the visible emission of the ligand and the near-infrared band of Er3+. These different procedures allow a detailed analysis of the transfer efficiency within a specific implementation of the Förster model for polymeric donors. The experimental values of the critical radius R0, ranging from 1.3 to 2.5 nm for the different blends, are in good agreement with theory for a wide interval of the physical and spectroscopic parameters. This suggests that other mechanisms for excitation transfer do not play a significant role in these materials. 相似文献
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A new microwave dielectric method for studying photoinitiated chain radical polymerization processes
Carlo Carlini Francesco Ciardelli Pier Angelo Rolla Elpidio Tombari 《Journal of Polymer Science.Polymer Physics》1987,25(6):1253-1261
Measurements of both real and imaginary parts of the dielectric constant at a fixed microwave frequency have been performed on n-butyl acrylate/poly(n-butyl acrylate) mixtures. The dielectric constant of the mixtures has been compared with that of neat n-butyl acrylate during UV photoinitiated polymerization. The values of the imaginary part of the dielectric constant thus obtained have allowed determination of the instantaneous monomer concentration and verified the kinetic equation for the photoinitiated polymerization process. The limits of validity of the method as well as its capability of providing detailed kinetic information are also discussed. 相似文献
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Carlo Carlini Valentina De Luise Anna Maria Raspolli Galletti Glauco Sbrana 《Journal of polymer science. Part A, Polymer chemistry》2006,44(1):200-206
Novel catalytic systems, prepared in situ by the oxidative addition of 8‐hydroxyquinoline ligands to bis(1,5‐cyclooctadiene)nickel(0) and activated by methylaluminoxane, were studied in ethylene polymerization. When 8‐hydroxyquinoline was employed, only oligomeric products were obtained. On the contrary, 5,7‐dinitro‐8‐hydroxyquinoline gave linear polyethylene (PE), but with a modest activity. For the catalyst based on 5‐nitro‐8‐hydroxyquinoline, the productivity was largely dependent on the content of free trimethylaluminum (TMA) present in the commercial aluminoxane. The progressive optimization of the TMA/oligomeric methylaluminoxane ratio increased the productivity, which reached 700 kg of PE/(mol of Ni × h), by an order of magnitude. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 200–206, 2006 相似文献
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Marina Brustolon Carlo Corvaja Giovanni Giacometti 《Theoretical chemistry accounts》1971,22(1):90-104
The proton hyperfine splitting constants of a large number of positive, negative, and neutral radicals, have been examined in term of the Heller-McConnell relation a
H=Bc cos2
whose validity is discussed. B is taken as a function of the energy of the singly occupied orbital and values are calculated by first order perturbation theory for the cases of a methyl, methylene, and dimethylene group attached to the system. Substantial agreement is found between theory and experiment indicating the correctness of the postulated cause of the B behaviour.
Zusammenfassung Die Konstante der Hyperfeinaufspaltung für -Protonen einer großen Anzahl positiver, negativer und neutraler -Radikale wurde mit der Beziehung von Heller und McConnell als Grundlage untersucht; die Gültigkeit dieser Beziehung wird diskutiert. B wird als von der Energie des einfach besetzten Orbitals abhängig angenommen und seine Werte mit Hilfe der Störungstheorie erster Ordnung für die Fälle von Methyl-, Methylen- und Dimethylengruppe am -System berechnet. Aus der guten Übereinstimmung zwischen Theorie und Experiment wird auf die Richtigkeit der postulierten Ursachen für das Verhalten von B geschlossen.相似文献
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Semiempirical iterative extended Hückel calculations are performed for the dipolar ions of cystine, cysteine, methionine and their selenium analogues. An attempt has been made to interprete the wave function of cysteine in terms of localized molecular orbitals.
Work performed with the financial support of the Consiglio Nazionale delle Ricerche. 相似文献
Zusammenfassung Semiempirische iterative Rechnungen wurden nach der erweiterten Hückeltheorie für die dipolaren Ionen Cystin, Cystein, Methionin und ihre Selen-Homologen durchgeführt. Für den Fall des Cysteins wurde die Wellenfunktion auf lokalisierte Orbitale transformiert.
Résumé On a analisé les ions dipolaires de la cystine, cystéine, methionine et leurs analogues séléniates avec la méthode semiempirique de Hückel étendue itérative. On a cherché à intérpreter la fonction d'onde pour la cystéine dans le schème des orbitales moleculaires localisées.
Work performed with the financial support of the Consiglio Nazionale delle Ricerche. 相似文献
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Carlo Sempi 《Annali dell'Universita di Ferrara》1977,23(1):25-28
Riassunto Si introducono alcune operazioni sullo spazio delle funzioni di ripartizione e si studiano, in corrispondenza, le proprietà
dell’entropia con errore
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Lavoro eseguito nell’ambito del G.N.f.M. del C.N.R. 相似文献
Summary Some operations on the space of distribution functions are introduced. The corresponding invariance properties of the entropy with error , are then studied.
Lavoro eseguito nell’ambito del G.N.f.M. del C.N.R. 相似文献
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Giuseppe Fachinetti Giovanni Fochi Carlo Floriani 《Journal of organometallic chemistry》1973,57(2):C51-C54
Reactions of azobenzene with dicarbonyldicyclopentadienyltitanium(II), Ti(π-C5H5)2(CO)2, and dicyclopentadienylvanadium(II), V(π-C5H5)2, have yielded the corresponding dicyclopentadienylmetal-azobenzene complexes. 相似文献