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131.
Sotirios G. Siampanis Georgios I. Giannopoulos Nikos D. Lagaros Antonios Hatziefremidis Stelios K. Georgantzinos 《Molecules (Basel, Switzerland)》2022,27(5)
In this study, a nonlinear, spring-based finite element approach is employed in order to predict the nonlinear mechanical response of graphyne structures under shear loading. Based on Morse potential functions, suitable nonlinear spring finite elements are formulated simulating the interatomic interactions of different graphyne types. Specifically, the four well-known types of γ-graphyne, i.e., graphyne-1 also known as graphyne, graphyne-2 also known as graphdiyne, graphyne-3, and graphyne-4 rectangular sheets are numerically investigated applying appropriate boundary conditions representing shear load. The obtained finite element analysis results are employed to calculate the in-plane shear stress–strain behaviour, as well as the corresponding mechanical properties as shear modulus and shear strength. Comparisons of the present graphyne shearing response predictions with other corresponding estimations are performed to validate the present research results. 相似文献
132.
Sven van Vliet Georgios Alachouzos Folkert de Vries Lukas Pfeifer Ben L. Feringa 《Chemical science》2022,13(33):9713
Chiral optical switches, which use light to control chirality in a reversible manner, offer unique properties and fascinating prospects in the areas of molecular switching and responsive systems, new photochromic materials and molecular data processing and storage. Herein, we report visible light responsive chiroptical switches based on tetrahedral boron coordination towards an easily accessible hydrazone ligand and optically pure BINOL. Upon instalment of a non-planar dibenzo[a,d]-cycloheptene moiety in the hydrazone ligand''s lower half, the enantiopure boron complex shows major chiroptical changes in the CD read-out after visible light irradiation. The thermal isomerization barrier in these chiroptical switching systems showed to be easily adjustable by the introduction of substituents onto the olefinic bond of the cycloheptene ring, giving profound control over their thermal stability. The control over their thermal stability in combination with excellent reversibility, photochemical properties and overall robustness of the complexes makes these BINOL-derived chiroptical switches attractive candidates for usage in advanced applications, e.g. photonic materials and nanotechnology.Chiroptical switches, which use light to control chirality in a reversible manner, offer unique properties and fascinating prospects in the areas of molecular responsive systems, new photochromic materials and molecular data processing and storage. 相似文献
133.
Georgios C VougioukalakisMichael Orfanopoulos 《Tetrahedron letters》2003,44(48):8649-8652
An efficient reaction between the azafullerene dimer, (C59N)2 and 9-substituted fluorenes leads to the formation of four new azafullerene monoadducts. 相似文献
134.
Thaylan Pinheiro Araújo Jordi Morales-Vidal Dr. Georgios Giannakakis Dr. Cecilia Mondelli Henrik Eliasson Prof. Rolf Erni Dr. Joseph A. Stewart Dr. Sharon Mitchell Prof. Núria López Prof. Javier Pérez-Ramírez 《Angewandte Chemie (International ed. in English)》2023,62(42):e202306563
Ternary Pd-In2O3/ZrO2 catalysts exhibit technological potential for CO2-based methanol synthesis, but developing scalable systems and comprehending complex dynamic behaviors of the active phase, promoter, and carrier are key for achieving high productivity. Here, we show that the structure of Pd-In2O3/ZrO2 systems prepared by wet impregnation evolves under CO2 hydrogenation conditions into a selective and stable architecture, independent of the order of addition of Pd and In phases on the zirconia carrier. Detailed operando characterization and simulations reveal a rapid restructuring driven by the metal-metal oxide interaction energetics. The proximity of InPdx alloy particles decorated by InOx layers in the resulting architecture prevents performance losses associated with Pd sintering. The findings highlight the crucial role of reaction-induced restructuring in complex CO2 hydrogenation catalysts and offer insights into the optimal integration of acid-base and redox functions for practical implementation. 相似文献
135.
Ioannis Polyzos Georgios Tsigaridas Mihalis Fakis John Parthenios Anastassios Fragos Vassilis Giannetas Peter Persephonis John Mikroyannidis 《Monatshefte für Chemie / Chemical Monthly》2001,132(1):169-175
Summary. Two-photon absorption induced fluorescence microscopy was used as a tool for the examination of the spatial distribution
of a thin dye film. The two-photon absorption induced fluorescence signal is essentially the same as that produced by excitation
with a single photon of equivalent energy. When femtosecond pulses are focused into a sample there is an intrinsic spatial
selectivity of the two-photon emission signal, since it is dependent upon the square of the light intensity. This has tremendous
implications in fluorescence microscopy. Since two-photon absorption is confined in a small region at the focal waist of an
objective lens, photodamage and photobleaching of the sample are significantly reduced. In addition, the two-photon signal
has inherent z-axis spatial resolution, which facilitates the construction of 3-D images. In the present work an application of this technique
to a thin film of a dye is presented. The method can generally be applied to thin films made from photonic polymers.
Received June 23, 2000. Accepted (revised) July 31, 2000 相似文献
136.
We describe an efficient generalized Born (GB) approximation for proteins, in which the interaction energy between two amino acids depends on the whole protein structure, but can be accurately computed from residue-pairwise information. Two results make the scheme pairwise. First, an accurate expression exists for the interaction energy between two residues R and R' that depends on the product B = BRBR' of their residue Born solvation radii. Second, this expression is accurately fitted by a parabolic function of B; the (three) fitting coefficients depend only on the pair RR', not on its environment. In effect, the quantity B captures all the information that is relevant about the pair's dielectric environment. The method is tested with calculations on several hundred structures of the proteins trpcage, BPTI, ubiqutin, and thoredoxin. It yields solvation energies in better agreement with Poisson calculations than a traditional GB formulation. We also compute the effect of the protein/solvent environment on the interactions between pairs of charged residues in the active site of the enzyme aspartyl-tRNA synthetase. Our method captures this effect as accurately as traditional GB. Because it is residue-pairwise, the method can be incorporated into efficient protocols for rotamer placement and computational protein design. 相似文献
137.
The principle of sequential injection (SI) was exploited to develop a fully automated pre-column derivatization procedure combined on-line to liquid chromatography (LC). Using SI-LC derivatization 14 amino acids were determined fluorimetrically in pharmaceuticals with o-phthaldialdehyde (OPA) as the derivatization reagent. The SI system was used for the handling of samples and reagents, on-line mixing and introduction to the LC injection system. Chemical (pH and reagents concentrations) and instrumental variables (sample and reagent volumes, reaction time and flow rate) were optimized to attain the highest reaction yield and detector signal. Reversed phase chromatographic resolution of 14 amino acids was achieved within 35 min using gradient elution. The automated operation of the coupled SI-LC system resulted in very satisfactory performance. The method was applied for the simultaneous determination of amino acids in pharmaceutical formulations. 相似文献
138.
Dr. Georgios Rotas Michael B. Thomas Dr. Ruben Canton-Vitoria Prof. Dr. Francis D'Souza Prof. Dr. Nikos Tagmatarchis 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(29):6652-6661
The preparation of an entirely supramolecular, multichromophoric azaborondipyrromethene ( ABDP )/zinc tetraphenylporphyrin ( ZnTPP )/exfoliated graphene ( GR ) nanoensemble was accomplished. The ABDP derivative bears glycol chains for enhancing solubility and a pyridine functionality for allowing coordination with ZnTPP . The ABDP / ZnTPP/GR nanoensemble was characterized in terms of morphology and composition by using complementary microscopy imaging, thermogravimetric analysis, Raman as well as steady-state and time-resolved absorption and emission spectroscopy. The photophysical and electrochemical assessment of ABDP / ZnTPP/GR as well as the binding properties of the ABDP / ZnTPP complex, employed as a reference, are presented. Energy and electron transfer events were observed in ABDP / ZnTPP upon photoexcitation. However, in the case of ABDP / ZnTPP/GR , the graphene-induced aggregation of the chromophores alters their electronic interactions, enhancing the energy/electron transfer process between them. 相似文献
139.
Manolis Sofiadis Dimitris Kalaitzakis John Sarris Tamsyn Montagnon Georgios Vassilikogiannakis 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(20):6814-6818
A method for asymmetric and site selective annulations at the γ and γ′ positions of cyclic 2‐enones with α,β‐unsaturated aldehydes has been developed. The organocatalysed [3+3]‐annulations proceed with high levels of regio‐, diastereo‐, and enantioselectivity, affording a series of high value fused carbocycles. Further elaboration gave key lactones (both bridged and fused). 相似文献
140.