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51.
Scolaro LM Plutino MR Romeo A Romeo R Ricciardi G Belviso S Albinati A 《Dalton transactions (Cambridge, England : 2003)》2006,(21):2551-2559
Reactions of the cationic complex ions [PtMe(Me2SO)(PP)]+ (PP = dppf (1,1'-bis(diphenylphosphino)ferrocene) and dppe (1,2-bis(diphenylphosphino)ethane)) with 5,10,15,20-tetrakis(4-pyridyl)-21H,23H-porphyrin (TpyP) led to the formation of the symmetrical tetraplatinated porphyrin complexes, [PtMe(PP)]4TpyP.X4 (PP = dppf, X = CF3SO3-, 3, and PP = dppe, X = BF4-, 5) containing the organometallic fragment [PtMe(PP)]. The precursor sulfoxide platinum complexes [PtMe(Me2SO)(dppf)]CF3SO3, 2 and [PtMe(Me2SO)(dppe)]BF4, 4, were prepared by halide abstraction from [PtMeCl(dppf)], 1, and by controlled protonolysis of [PtMe2(dppe)] respectively, in the presence of a small amount of dimethyl sulfoxide. All these starting platinum(II) compounds, as well as the porphyrin derivatives 3 and 5, were fully characterized through elemental analysis, 1H NMR mono- and bidimensional, 31P[1H], 31P-1H HMBC, UV/Vis absorption and photophysical measurements. The X-ray crystal structure of complex 1 has been determined. In order to ascertain the electronic influence of ferrocene, the spectroscopic and redox properties of 3 were compared with those of TPyP and of the analogous 5. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), 1H and 31P NMR data, and UV/Vis data, all suggest a certain degree of communication between the central porphyrin and the peripheral hetero-bimetallic fragments. In contrast, no detectable interaction among these peripheral groups seem to come into play. Unlikely from the porphyrin derivative 5, formation of well defined fluorescent mesoscopic ring structures was easily achieved by simple evaporation from diluted dichloromethane solutions of 3. 相似文献
52.
A Truncated Newton Method for the Solution of Large-Scale Inequality Constrained Minimization Problems 总被引:1,自引:0,他引:1
Francisco Facchinei Giampaolo Liuzzi Stefano Lucidi 《Computational Optimization and Applications》2003,25(1-3):85-122
A new active set Newton-type algorithm for the solution of inequality constrained minimization problems is proposed. The algorithm possesses the following favorable characteristics: (i) global convergence under mild assumptions; (ii) superlinear convergence of primal variables without strict complementarity; (iii) a Newton-type direction computed by means of a truncated conjugate gradient method. Preliminary computational results are reported to show viability of the approach in large scale problems having only a limited number of constraints. 相似文献
53.
De Luca L Giacomelli G Porcheddu A Salaris M Taddei M 《Journal of combinatorial chemistry》2003,5(4):465-471
The synthesis of libraries of substituted pyrazoles and isoxazoles has been developed via in situ generation of polymer-bound enaminones. The synthetic protocol makes use of commercially available aniline cellulose, a low-cost and versatile biopolymer, under very mild conditions. This new support allowed us to carry out reactions in polar solvents under both conventional heating and MW irradiation without degradation of the polymer. The reaction between cellulose-bound enaminone and hydroxylamine or hydrazines to afford the target heterocycles in high yields directly in solution is the key step. The support can be conveniently recycled. 相似文献
54.
Giovanni Meazza Giampaolo Zanardi Paolo Piccardi 《Journal of heterocyclic chemistry》1993,30(2):365-371
Trifluoromethyl-substituted pyrazoles were synthesized via 1,3-dipolar cycloaddition from sydnones 2a-j and 1-aryl-3,3,3-trifluoro-propynes 5a-f. The regioselectivity of the reaction and the spectroscopic characteristics of the products are discussed. 相似文献
55.
Barone G Duca D Silvestri A Gomez-Paloma L Riccio R Bifulco G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(14):3240-3245
Ab initio calculations at the Hartree-Fock level with full-geometry optimization using the 6-31G(d) basis set, and GIAO (gauge including atomic orbitals) (13)C NMR chemical shifts, are presented here as a support in the study of the stereochemistry of low-polar organic compounds having an open-chain structure. Four linear stereoisomers, fragments of a natural product previously characterized by experimental (13)C NMR spectra, which possesses three stereogenic centers, 11 carbon atoms, and 38 atoms in total, were considered. Conformational searches, by empirical force-field molecular dynamics, pointed out the existence of 8-13 relevant conformers per stereoisomer. Thermochemical calculations at the ab initio level in the harmonic approximation of the vibrational modes, allowed the evaluation, at 298.15 K, of the standard Gibbs free energy of the conformers. The (13)C NMR chemical shift of a given carbon atom in each stereoisomer was considered as the average chemical shift value of the same atom in the different conformers. The averages were obtained by the Boltzmann distribution, using the relative standard free energies as weighting factors. Computed parameters related to linear correlation plots of experimental (13)C chemical shifts versus the corresponding computed average data allowed us to distinguish among the four stereoisomers. 相似文献
56.
Pier Luigi Ferrarini Giuliana Biagi Oreste Livi Giampaolo Primofiore Marino Carpen 《Journal of heterocyclic chemistry》1981,18(5):1007-1010
Some 3-substituted-5,6-dihydro[1,8]naphthyrido[3,2-c][1,8]naphthyridines (V) were obtained by the condensation of 7-substituted-2,3-dihydro-1,8-naphthyridin-4-(1H)ones (IV) with 2-aminonicotinaldehyde. All of the 5,6-dihydro derivatives V were transformed into the fully aromatic compounds VI by refluxing with nitrobenzene. 相似文献
57.
Antonio Da Settimo Anna Maria Marini Giampaolo Primofiore Federico Da Settimo Daniele Bertini 《Journal of heterocyclic chemistry》1998,35(1):57-60
The synthesis of derivatives of two new heterocyclic systems, purino[8,7-b][1,3]benzothiazine and pyrido[3′,2′:5,6][1,3]thiazino[3,2-f]purine, was effected by the Ullmann reaction between 8-mercaptotheophylline or 8-bromotheophylline with the appriopriately substituted benzoic or nicotinic acid, respectively. The 8,8′-dithiobistheophylline is also reported. 相似文献
58.
Paola Caroti Carlo Ceccotti Antonio Da Settimo Fabio Palla Giampaolo Primofiore 《Journal of heterocyclic chemistry》1986,23(6):1833-1836
Reaction between 2-chloropyridine-3-carbonyl chloride and 1-alkyl-2-aminobenzimidazoles afforded the N-(1-alkylbenzimidazole-2-yl)-2-chloropyridine-3-carboxamides, which were cyclized to 5,7-dihydro-5-oxopyrido[3′,2′:5,6]pyrimido[1,2-a]benzimidazoles. The assigned structures of these hitherto unknown heterocyclic compounds were confirmed by their ir and 1H nmr spectra and chemical evidence. 相似文献
59.
Ab initio calculations were performed on the tautomers and conformers of N-hydroxyurea using a 6-31G ** basis set. The minimum-energy structures have been found and the importance of the intramolecular hydrogen bond as the stabilizing factor was pointed out. © 1996 John Wiley & Sons, Inc. 相似文献
60.
M. Barbui A. Andrighetto C. Antonucci S. Carturan F. Cervellera S. Cevolani M. Cinausero P. Colombo A. Dainelli P. Di Bernardo F. Gramegna G. Maggioni G. Meneghetti C. Petrovich L. Piga G. Prete V. Rizzi M. Santana-Leitner M. Tonezzer P. Zanonato D. Zafiropoulos 《The European physical journal. Special topics》2007,150(1):275-276
A Direct Target for a mid-term RIB ISOL-type facility is being developed at LNL, in the framework of the R&D for the SPES
project [1]. Using a 40 MeV proton beam impinging on a UCx thick target of 2.5 g/cm3 density, a production rate of 1013 in target fissions per second is expected [2]. The crucial point, when short-lived isotopes are produced in the target, is
to build systems (target + ion source) with good release properties and high efficiency.
Monte Carlo simulations were performed using the GEANT4 toolkit [3] and the RIBO code [4] in order to optimize our target
geometry and to estimate the average release time. 相似文献