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121.
Janina Rodakiewicz-Nowak PaweŁ Nowak Dorota Rutkowska-Żbik Marcin Ptaszek Oskar Michalski Grzegorz Mynarczuk 《Supramolecular chemistry》2013,25(8):643-647
The UV/Vis absorption spectra and cyclic voltammograms (CV) of the Cu(II) and Ni(II) complexes of γ,γ'-alkoxycarbonyl derivatives of α,α'- diphenyldibenzo-tetraaza[14]annulene are analyzed and compared. The observed ratio of absorption intensities at the peaks of π-π* transitions is linearly correlated with the difference of HOMO and LUMO energy levels of the substituents. Moreover, the measured values of the mid-peak potential of metal redox reactions on a Pt electrode in DMF are linearly correlated with the ionization potential values of the appropriate substituents. 相似文献
122.
123.
Wojciech Zając Dariusz Rusinek Kun Zheng Janina Molenda 《Central European Journal of Chemistry》2013,11(4):471-484
Four proton conducting oxides of perovskite structure: BaZrO3, SrZrO3, BaCeO3 and SrCeO3 doped with 5 mol.% of gadolinium are compared in terms of crystal structure, microstructure, sinterability, water sorption ability, ionic transference number, electrical conductivity and stability towards CO2. Relations between proton conductivity, structural and chemical parameters: pseudo-cubic unit cell volume, lattice free volume, tolerance factor, crystal symmetry and electronegativity are discussed. The grain boundary resistance is shown to be the limiting factor of total proton-conductivity for the materials examined. The highest proton conductivity was observed for BaCeO3, however, it turned out to be prone to degradation in CO2-containing atmosphere and reduction at high temperatures. On the other hand, Ba and Sr zirconates are found to be more chemically stable, but exhibit low electrical conductivity. Electrical conductivity relaxation upon hydration is used to calculate proton diffusion coefficient. Selected materials were tested as electrolytes in solid oxide fuel cells. 相似文献
124.
125.
Guillermo?Orts-GilEmail author Kishore?Natte Daniela?Drescher Harald?Bresch Alexandre?Mantion Janina?Kneipp Werner??sterle 《Journal of nanoparticle research》2011,13(4):1593-1604
The size, surface charge and agglomeration state of nanoparticles under physiological conditions are fundamental parameters
to be determined prior to their application in toxicological studies. Although silica-based materials are among the most promising
candidates for biomedical applications, more systematic studies concerning the characterisation before performing toxicological
studies are necessary. This interest is based on the necessity to elucidate the mechanisms affecting its toxicity. We present
here TEM, SAXS and SMPS as a combination of methods allowing an accurate determination of single nanoparticle sizes. For the
commercial material, Ludox TM50 single particle sizes around 30 nm were found in solution. DLS measurements of single particles
are rather affected by polydispersity and particles concentration but this technique is useful to monitor their agglomeration
state. Here, the influence of nanoparticle concentration, ionic strength (IS), pH and bath sonication on the agglomeration
behaviour of silica particles in solution has been systematically investigated. Moreover, the colloidal stability of silica
particles in the presence of BSA has been investigated showing a correlation between silica and protein concentrations and
the formation of agglomerates. Finally, the colloidal stability of silica particles in standard cell culture medium has been
tested, concluding the necessity of surface modification in order to preserve silica as primary particles in the presence
of serum. The results presented here have major implications on toxicity investigations because silica agglomeration will
change the probability and uptake mechanisms and thereby may affect toxicity. 相似文献
126.
The excitation wavelength dependence of the steady-state and time-resolved emission spectra of ethyl 5-(4-aminophenyl)-3-amino-2,4-dicyanobenzoate (EAADCy) in tetrahydrofuran (THF) at room temperature has been examined. It is found that the ratio of the fluorescence intensity of the long-wavelength and short-wavelength fluorescence bands strongly depends on the excitation wavelength, whereas the wavelengths of the fluorescence excitation and fluorescence bands maxima are independent on the observation/excitation wavelengths. The dynamic Stokes shift of fluorophore in locally excited (LE) and intramolecular charge transfer (ICT) states has been studied with a time resolution about 30 ps. The difference between Stokes shift in the LE and ICT states was attributed to the solvent response to the large photoinduced dipole moment of EAADCy in the fluorescent charge transfer state. On this base we can state that, the relaxation of the polar solvent molecules around the fluorophore was observed. 相似文献
127.
Joanna Biernacka Katarzyna Betlejewska-Kielak Janina Witowska-Jarosz Ewa Kłosińska-Szmurło Aleksander P. Mazurek 《Journal of inclusion phenomena and macrocyclic chemistry》2014,78(1-4):437-443
Complexation of alendronate sodium (AlnNa) with β-cyclodextrin (β-CD) was studied by means of ESI-mass spectrometry. The experimental results show that stable 1:1 inclusion complexes between selected bisphosphonates and β-CD were formed. In addition, complexes with different stoichiometry were observed. DFT/B3LYP calculations were performed to elucidate the different inclusion behavior between alendronate and β-CD. Molecular modeling showed that the inclusion complex of Aln-β-CD where the two phosphonate groups bound to the central carbon atom of bisphosphonate were inserted into the cavity of β-CD from its “top” side was thermodynamically more favorable than when they were inserted from its “bottom” side; the complexation energy was ?74.05 versus ?60.85 kcal/mol. The calculations indicated that the formation of conventional hydrogen bonds was the main factor for non-covalent β-CD:Aln complex formation and stabilization in the gas phase. 相似文献
128.
The 14N relaxation time of pyrrole in cyclohexane, carbon tetrachloride and pentafluororyridine solution has been determined at a number of temperatures through a line-shape analysis of the imido proton pmr signal of pyrrole (scalar relaxation of the second kind). The viscosity of pyrrole in the same solvents has also been measured. The results are discussed in terms of solvent effects on the association equilibria of pyrrole. 相似文献
129.
Bohdan Mroziewicz Emil Kowalczyk Lech Dobrzanski Jacek Ratajczak Stainslaw J. Lewandowski 《Optical and Quantum Electronics》2007,39(7):585-595
Performance of external cavity diode lasers with silicon gratings produced by E-beam writing and subsequent reactive ion etching
is described. Optical amplifiers used in the experiments were based on single quantum well heterostructures grown by molecular
beam epitaxy. The lasers were set up in the Littrow configuration and have been designed to allow for wavelength tuning in
the range centred at 960 nm. 相似文献
130.
This paper is a continuation of our earlier works [1,2] on the fractal structure of expanding and subexpanding meromorphic functions of the form F = H o exp o Q, where H and Q are non-constant rational maps. Under some assumptions on the forward trajectories of asymptotic values ofF we define a class of summable potentials for the maps f of the punctured cylinder induced by F. We prove the existence and uniqueness of Gibbs states for these potentials. 相似文献