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261.
B Seger AB Laursen PC Vesborg T Pedersen O Hansen S Dahl I Chorkendorff 《Angewandte Chemie (International ed. in English)》2012,51(36):9128-9131
A low-cost substitute: A titanium protection layer on silicon made it possible to use silicon under highly oxidizing conditions without oxidation of the silicon. Molybdenum sulfide was electrodeposited on the Ti-protected n(+) p-silicon electrode. This electrode was applied as a photocathode for water splitting and showed a greatly enhanced efficiency. 相似文献
262.
Forniés J Ibáñez S Lalinde E Martín A Moreno MT Tsipis AC 《Dalton transactions (Cambridge, England : 2003)》2012,41(12):3439-3451
The reaction between (NBu(4))[Pt(bzq)(C(6)F(5))(2)] (1, bzq = 7,8-benzoquinolate) and AgClO(4) in a 1 : 1 molar ratio, in acetone, gives the polymer [{Pt(bzq)(C(6)F(5))(2)}Ag](n) (2). The reaction of 2 with equimolecular amounts of PPh(3) and SC(4)H(8) (tht) produces the bimetallic complexes [{Pt(bzq)(C(6)F(5))(2)}AgL] (L = PPh(3) (3), tht (4)). For L = py, decomposition takes place and [Pt(bzq)(C(6)F(5))py] (5) is obtained. All these complexes have been characterized by X-ray diffraction. The most interesting features of complexes 2-4 is the presence of Pt-Ag bonds, with Pt-Ag distances of ca. 2.75 ?. Besides, the silver centres establish short η(1) bonding interactions with the C(ipso) of the bzq ligands, with distances Ag-C of ca. 2.45 ?. Complex 2 is a one-dimensional infinite chain in which the fragments "Pt(bzq)(C(6)F(5))(2)(-)" and Ag(+) alternate. On the other hand, complexes 1 and 3-5 show intermolecular pairing through π···π interactions between the aromatic rings of the bzq ligand, having interplanar separations of ca. 3.5 ?. Complex 2 dissolves in donor solvents (acetone, THF) as discrete bimetallic solvated fragments [{Pt(bzq)(C(6)F(5))(2)}AgS(n)] (S = solvent), similar to complexes 3 and 4. The persistence of the Pt-Ag bond in 2-4, supported by multinuclear NMR spectroscopy, causes a significant blue-shift in the lowest-lying absorption in relation to 1. This fact is attributed (TD-DFT) to a remarkable modification of the orbitals contributing to the HOMO, which changes the character of the transition from (1)LC/(1)MLCT in 1 to admixture (1)L'LCT/(1)MLCT in the bimetallic complexes. The low energy feature (490-530 nm) of 2 in solid state is attributed to CT from the Pt fragments to the Ag centers. Complexes 2-4 are only emissive in rigid media (solid and glasses). In the solid state, the metallic chain 2 exhibits a bright orange emission (560 nm, 298 K; 590 nm, 77 K), assigned to an excited state involving charge transfer from the platinum fragment with a remarkable contribution of C(6)F(5) (Ar(f)) rings to the Pt-Ag bond ((3)LMM'CT/(3)L'M'CT). However, 3 and 4 exhibit in solid state at 298 K a vibronic band, which is clearly resolved in two close non-equilibrated bands at 77 K in 3, tentatively ascribed to a mixture of (3)MLCT/(3)L'LCT transitions modified by the formation of the Pt-Ag bond. In glassy solution (77 K) 2-4 display a vibronic emission ascribed primarily to (3)LC character. 相似文献
263.
Kleiman-Shwarsctein A Laursen AB Cavalca F Tang W Dahl S Chorkendorff I 《Chemical communications (Cambridge, England)》2012,48(7):967-969
A novel method for the deposition of RuO(2) from RuO(4)(g) on diverse metal oxides has been developed by grafting dopamine onto the otherwise un-reactive metal oxide surface. Oxygen evolution reaction on TiO(2) and the photoelectrochemical improvement of WO(3) by deposition of RuO(2) are just a few examples where this novel deposition method can be used. 相似文献
264.
A general mapping between the energy of pertinent magnetic solutions and the diagonal terms of the spin Hamiltonian in a local representation provides the first general framework to extract accurate values for the many body terms of extended spin Hamiltonians from periodic first-principle calculations. Estimates of these terms for La2CuO4, the paradigm of high-Tc superconductor parent compounds, and for the SrCu2O3 ladder compound are reported. For La2CuO4, present results support experimental evidence by Toader et al. [Phys. Rev. Lett. 94, 197202 (2005)10.1103/PhysRevLett.94.197202]. For SrCu2O3 even larger four-body spin amplitudes are found together with Jl/Jr = 1 and non-negligible ferromagnetic interladder exchange. 相似文献
265.
The magnetic interactions in organic diradicals, dinuclear inorganic complexes and ionic solids are presented from a unified point of view. Effective Hamiltonian theory is revised to show that, for a given system, it permits the definition of a general, unbiased, spin model Hamiltonian. Mapping procedures are described which in most cases permit one to extract the relevant magnetic coupling constants from ab initio calculations of the energies of the pertinent electronic states. Density functional theory calculations within the broken symmetry approach are critically revised showing the contradictions of this procedure when applied to molecules and solids without the guidelines of the appropriate mapping. These concepts are illustrated by describing the application of state-of-the-art methods of electronic structure calculations to a series of representative molecular and solid state systems. 相似文献
266.
Liquid chromatography (LC) coupled to hybrid quadrupole time-of-flight (QTOF) mass spectrometry (MS) is a useful analytical
tool in the elucidation and confirmation of transformation products (TPs)/metabolites of pesticides with a wide range of polarity,
in both environmental and biological samples. Firstly, the versatility of LC allows the determination of very distinct TPs/metabolites
as chromatographic conditions can be easily changed and optimized depending on the analytical problem. Secondly, the mass
accuracy provided by the TOF analyser allows the assignment of a highly probable empirical formula for each compound and the
differentiation between nominal isobaric compounds. Finally, the possibility of performing MS/MS spectra with accurate mass
measurements can been used for the final characterization of the TPs/metabolites detected and for the differentiation of isomeric
compounds. In this study, the insecticide diazinon was used as model compound, and its photodegradation and metabolism have
been investigated by LC-QTOF-MS. On one hand, environmental spiked water was irradiated with a mercury lamp for 9 days, sampling
3-mL aliquots approximately every 12 h. On the other hand, both in vitro and in vivo metabolism experiments were carried out
with different substrate concentrations and incubation times. After centrifugation, and protein precipitation in the in vitro
and in vivo studies, 50-μL aliquots of both environmental and biological samples were directly injected into the LC electrospray
ionization QTOF system. The most important transformation processes were found to be hydrolysis of the ester moiety, hydroxylation
in the aromatic ring or in one of the alkylic groups, oxidation of the sulfur atom on the P=S cleavage or a combination of
these processes, with the highest number of compounds being found in the photodegradation study. Very polar compounds, such
as diethyl phosphate and diethyl thiophosphate, were detected after direct injection of the aqueous sample, which was feasible
owing to the characteristics of the LC. In MS mode, mass errors were below 3 mDa, leading to an empirical formula for each
compound. MS/MS spectra with accurate mass were used for the final elucidation of the compounds detected. 相似文献
267.
Emilio Defez Antonio Hervás Javier Ibá?ez Michael M. Tung 《Mediterranean Journal of Mathematics》2012,9(4):865-882
This paper deals with the construction of approximate solution of first-order matrix linear differential equations using higher-order matrix splines. An estimation of the approximation error, an algorithm for its implementation and some illustrative examples are included. 相似文献
268.
Francisco J. Ariza-López Domingo Barrera Salah Eddargani María José Ibáñez Juan F. Reinoso 《Mathematical Methods in the Applied Sciences》2023,46(2):1687-1698
A nonstandard low-cost spline approximation method for approximating bivariate functions is constructed. It is applied for Digital Elevation approximation and then its accuracy in the downscaling process is studied. 相似文献
269.
Determining the Physico-Chemical Composition of Biomolecular Condensates from Spatially-Resolved NMR
Christian F. Pantoja Dr. Alain Ibáñez de Opakua Maria-Sol Cima-Omori Prof. Dr. Markus Zweckstetter 《Angewandte Chemie (International ed. in English)》2023,62(17):e202218078
Liquid-Liquid phase separation has emerged as fundamental process underlying the formation of biomolecular condensates. Insights into the composition and structure of biomolecular condensates is, however, complicated by their molecular complexity and dynamics. Here, we introduce an improved spatially-resolved NMR experiment that enables quantitative analysis of the physico-chemical composition of multi-component biomolecular condensates in equilibrium and label-free. Application of spatially-resolved NMR to condensates formed by the Alzheimer's disease-associated protein Tau demonstrates decreased water content, exclusion of the molecular crowding agent dextran, presence of a specific chemical environment of the small molecule DSS, and ≈150-fold increased concentration of Tau inside the condensate. The results suggest that spatially-resolved NMR can have a major impact in understanding the composition and physical chemistry of biomolecular condensates. 相似文献