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1.
J.T. Elizalde Galindo A.H. Adair C.E. Botez V. Corral Flores D. Bueno Baques L. Fuentes Cobas J.A. Matutes-Aquino 《Applied Physics A: Materials Science & Processing》2007,87(4):743-747
Measurements of ac-susceptibility and dc-magnetization were carried out on samples of Ni1-xZnxFe2O4 nanoparticles (x=0, 0.25, 0.5, 0.75) with average diameters 〈D〉≈7 nm. Values of the superparamagnetic blocking temperature
T̄B were obtained from the characteristic temperature behavior of the imaginary susceptibility χimag. An Arrhenius-type law, which accurately describes the relationship between the observation time τobs and the blocking temperature, was used to determine the effective energy barrier to magnetization reversal Ueff. A Zn-content dependence of the energy barrier is observed, where Ueff changes little for 0≤x≤0.25, it peaks at x=0.5, and decreases back upon further Zn-doping. The large increase of Ueff at x=0.5 is attributed to an enhanced magnetic anisotropy induced by the crossover between two spatial arrangements of spins
in the A and B sub-lattices of the ferrimagnetic inverse spinel.
PACS 75.50.Bb; 75.50.Gg; 75.30.Et 相似文献
2.
R. M. Aron P. Galindo D. Garcí a M. Maestre 《Transactions of the American Mathematical Society》1996,348(2):543-559
A Banach space is known to be Arens regular if every continuous linear mapping from to is weakly compact. Let be an open subset of , and let denote the algebra of analytic functions on which are bounded on bounded subsets of lying at a positive distance from the boundary of We endow with the usual Fréchet topology. denotes the set of continuous homomorphisms . We study the relation between the Arens regularity of the space and the structure of .
3.
Fehr C Chaptal-Gradoz N Galindo J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(4):853-858
Two efficient enantioselective syntheses of the more active (S,S)-enantiomer of the powerful musk odorant Vulcanolide are described. In both syntheses, the key step is an enantioselective protonation of a ketone enolate. A third enantioselective protonation, of a thiol ester enolate, was applied for the determination of the absolute configuration of Vulcanolide by comparison with a known compound. 相似文献
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5.
The π‐Back‐Bonding Modulation and Its Impact in the Electronic Properties of CuII Antineoplastic Compounds: An Experimental and Theoretical Study
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Juan Carlos García‐Ramos Dr. Rodrigo Galindo‐Murillo Araceli Tovar‐Tovar Ana Luisa Alonso‐Saenz Virginia Gómez‐Vidales Dr. Marcos Flores‐Álamo Dr. Luis Ortiz‐Frade Dr. Fernando Cortes‐Guzmán Dr. Rafael Moreno‐Esparza Prof. Antonio Campero Prof. Lena Ruiz‐Azuara 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(42):13730-13741
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We report experimental measurements of the phase behavior of mixtures of thin (charged semiflexible fd virus) and thick (fd-PEG, fd virus covalently coated with polyethylene glycol) rods with diameter ratio varying from 3.7 to 1.1. The phase diagrams of the rod mixtures reveal isotropic-nematic, isotropic-nematic-nematic, and nematic-nematic coexisting phases with increasing concentration. In stark contrast to predictions from earlier theoretical work, we observe a nematic-nematic coexistence region bound by a lower critical point. Moreover, we show that a rescaled Onsager-type theory for binary hard-rod mixtures qualitatively describes the observed phase behavior. 相似文献
8.
Folded 2,5-diazapent-3-ene metallacycle in ene-diamido group 4 metal compounds: DFT and AIM analyses
Agustín Galindo Diego del Río Andrea Ienco 《Journal of organometallic chemistry》2004,689(18):2847-2852
Mononuclear complexes, which contain a dianionic ene-diamido ligand bound to a group 4 metal atom in the formal d0 configuration, are analyzed by the DFT method to interpret the electronic origin of the folding at the five-membered 2,5-diazapent-3-ene metallacycle moiety. Geometry optimizations were carried out for the following models, TiCl2[o-(Me3SiN)2C6H4], Ti(OPh)2(DAD), CpTiCl(DAD), CpTiMe(DAD) and Cp2Zr(DAD) (DAD = HNCHCHNH). They show some common electronic features, the nature of the HOMO, in particular. In all cases, the latter results from the donation of a filled ene-diamido level into an empty σ metal orbital, this being maximized upon the folding of the metallacycle. Such a geometric rearrangement involves the filled nitrogen pπ lobes, while the CC π bond remains essentially uninvolved. The feature is confirmed by the application of the atom in molecules (AIM) theory, that provides no evidence of critical points between the metal center and the pair of two carbon atoms. 相似文献
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10.
Grirrane A Pastor A Galindo A Ienco A Mealli C Rosa P 《Chemical communications (Cambridge, England)》2003,(4):512-513
The compound [Mn(tda)(bipy)] (tda = S(CH2COO)2(2-)) features the first structurally characterized tetra-carboxylate dimanganese antiferromagnetic system with 'copper acetate' core; the binuclear units, completed by bipyridine chelates, are doubly chained by the tda anions that adopt an unprecedented mu,mu'-eta1,eta1,eta1,eta1 coordination mode. 相似文献