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81.
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Frederik Tielens 《Surface science》2006,600(2):357-365
Periodic-DFT has been used to study the acid-base properties of MgO(1 0 0) layers interconnected with an ice filling. The insertion of HCl by substitution of one water molecule shows that all the protons are adsorbed on the surface oxygen atoms forming hydroxyl groups; the Cl− ions are weakly bound to surface cations, generating a monolayer with the adsorbed water molecules. For the insertion of NaOH also by substitution of one water molecule, it is found that OH− ions remain in solution close to the Na+ ions, forming ion pairs or chains. Depending on the number of water molecules present, the sodium ions are bi-, tri- or tetra-coordinated. Finally, some aspects concerning corrosion have been highlighted. 相似文献
83.
Peter Lievens Peter Thoen Steven Bouckaert Wim Bouwen Erno Vandeweert Frederik Vanhoutte Horst Weidele Roger E. Silverans 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1997,42(3):231-235
We report on the production of small and medium size lithium and lithium oxide clusters by a laser vaporization cluster source. The isotopomeric distribution of natural lithium allowed to identify LikO clusters as the most abundant components in the mass spectrum. Photoionization efficiency curves of LikO clusters with photon energies from 3.4 to 4.7 eV were measured for 8 ≤ k ≤ 27. Using linear extrapolation of the increase in photoionization efficiency with photon energy, ionization potentials were extracted. With the chemical bond of the O2- anion to two Li atoms, leaving n = k-2 valence electrons in the (Li2O)Lin clusters, clear shell closure effects are present at n = 8 and n = 20. 相似文献
84.
Wim M. De Borggraeve Bie M.P. Verbist Frederik J.R. Rombouts Vijaykumar G. Pawar Wim J. Smets Laila Kamoune Jo Alen Erik V. Van der Eycken Frans Compernolle Georges J. Hoornaert 《Tetrahedron》2004,60(50):11597-11612
In this paper, a synthetic approach for functionalised 5-aminopiperidinone-2-carboxylate (APC) systems as non-pro cis-peptide bond containing external β-turn mimics is presented. The scope and limitations of the synthetic method are discussed and the potential turn inducing properties of a model compound are evaluated by means of molecular modelling and NMR analysis. 相似文献
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Experimental and Theoretical Study of the Reactivity of Gold Nanoparticles Towards Benzimidazole‐2‐ylidene Ligands
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Dr. María Rodríguez‐Castillo Gustavo Lugo‐Preciado Dr. Danielle Laurencin Dr. Frederik Tielens Dr. Arie van der Lee Dr. Sébastien Clément Dr. Yannick Guari Dr. José M. López‐de‐Luzuriaga Dr. Miguel Monge Dr. Françoise Remacle Dr. Sébastien Richeter 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(30):10446-10458
The reactivity of benzimidazol‐2‐ylidenes with respect to gold nanoparticles (AuNPs) has been investigated using a combined experimental and computational approach. First, the grafting of benzimidazol‐2‐ylidenes bearing benzyl groups on the nitrogen atoms is described, and comparisons are made with structurally similar N‐heterocyclic carbenes (NHCs) bearing other N‐groups. Similar reactivity was observed for all NHCs, with 1) the erosion of the AuNPs under the effect of the NHC and 2) the formation of bis(NHC) gold complexes. DFT calculations were performed to investigate the modes of grafting of such ligands, to determine adsorption energies, and to rationalize the spectroscopic data. Two types of computational models were developed to describe the grafting onto large or small AuNPs, with either periodic or cluster‐type DFT calculations. Calculations of NMR parameters were performed on some of these models, and discussed in light of the experimental data. 相似文献
87.
Replacement of Water Molecules in a Phosphate Binding Site by Furanoside‐Appended lin‐Benzoguanine Ligands of tRNA‐Guanine Transglycosylase (TGT)
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Dr. Luzi J. Barandun Frederik R. Ehrmann Daniel Zimmerli Dr. Florian Immekus Maude Giroud Claudio Grünenfelder Dr. W. Bernd Schweizer Dr. Bruno Bernet Michael Betz Prof. Dr. Andreas Heine Prof. Dr. Gerhard Klebe Prof. Dr. François Diederich 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):126-135
The enzyme tRNA‐guanine transglycosylase has been identified as a drug target for the foodborne illness shigellosis. A key challenge in structure‐based design for this enzyme is the filling of the polar ribose‐34 pocket. Herein, we describe a novel series of ligands consisting of furanoside‐appended lin‐benzoguanines. They were designed to replace a conserved water cluster and differ by the functional groups at C(2) and C(3) of the furanosyl moiety being either OH or OMe. The unfavorable desolvation of Asp102 and Asp280, which are located close to the ribose‐34 pocket, had a significant impact on binding affinity. While the enzyme has tRNA as its natural substrate, X‐ray co‐crystal structures revealed that the furanosyl moieties of the ligands are not accommodated in the tRNA ribose‐34 site, but at the location of the adjacent phosphate group. A remarkable similarity of the position of the oxygen atoms in these two structures suggests furanosides as a potential phosphate isoster. 相似文献
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