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211.
Dichtel WR Serin JM Edder C Fréchet JM Matuszewski M Tan LS Ohulchanskyy TY Prasad PN 《Journal of the American Chemical Society》2004,126(17):5380-5381
A new approach to two-photon excited photodynamic therapy has been developed. A dendritic array of eight donor chromophores capable of two-photon absorption (TPA) was covalently attached to a central porphyrin acceptor. Steady-state fluorescence measurements demonstrated that the donor chromophores transfer excited-state energy to the porphyrin with 97% efficiency. Two-photon excitation of the donor chromophores at 780 nm resulted in a dramatic increase in porphyrin fluorescence relative to a porphyrin model compound. Enhanced singlet oxygen luminescence was observed from oxygen-saturated solutions of the target compound under two-photon excitation conditions. 相似文献
212.
213.
Canac Y Lepetit C Abdalilah M Duhayon C Chauvin R 《Journal of the American Chemical Society》2008,130(26):8406-8413
The coordinating properties of the diaminocarbene (A) and phosphonium ylide (B) ligand types have been investigated systematically through a test family of C,C-chelating ligands containing two moieties of either kind. The overall character of o-C6H4A(a)B(b) ligands (a + b = 2) has been analyzed from the IR CO stretching frequencies of isostructural complexes [(eta(2)-C6H4A(a)B(b))Rh(CO)2][TfO]. The test moieties A = NC2H2N(+)(Me)C(-) and B = Ph2P(+)CH2(-) were first considered. While the ligands bearing at least one diaminocarbene end (AA, a = 2 and AB, a = 1) could be generated (and trapped by complexation), the bis-ylide case BB (a = 0) proved to be awkward: treatment of the dication C6H4(P(+)Ph2Me)2 with n-BuLi indeed lead to the Schmidbaur's carbodiphosphorane Ph3PCPPh2Me, through an unprecendented ylido-pentacoordinated phosphorane which could be fully characterized by NMR techniques. The bis-ylide ligand type C6H4B2 could however be generated by bridging the phosphonium methyl groups by a methylene link (B2 = (P(+)Ph2CH(-))2CH2), preventing the formation of the analogous highly strained carbodiphosphorane. The three complexes [(eta(2)-C6H4A(a)B(b))Rh(CO)2][TfO] were fully characterized, including by X-ray diffraction analysis and (103)Rh NMR spectroscopy. Comparison of their IR spectra indicated that the A2 type bis-NHC ligand is less donating than the hybrid AB type, which is itself less donating than the B2 type bis-ylide ligand. The excellent linear variation of the nu(CO) frequencies vs a (= 0, 1, 2) shows that the coordinating moieties act in a pseudoindependent way. This was confirmed by DFT calculations at the B3PW91/6-31G**/LANL2DZ*(Rh) level. It is therefore demonstrated that a phosphonium ylide ligand is a stronger donor than a diaminocarbene ligand. 相似文献
214.
Fellah FZ Costes JP Dahan F Duhayon C Novitchi G Tuchagues JP Vendier L 《Inorganic chemistry》2008,47(14):6444-6451
The study of the Cu-Gd interaction is simplified by the use of heteronuclear Cu-Gd complexes of low nuclearity, such as dinuclear Cu-Gd or trinuclear Cu-Gd-Cu complexes. In the large majority of cases published until now, this interaction presents the advantage of being ferromagnetic. Among the known examples, the complexes with the largest J values have been prepared with use of symmetric Schiff base compartmental ligands, so that the active cores of the molecules involve two phenoxo bridges between the copper and gadolinium ions. Keeping this remark in mind, we decided to synthesize simple complexes in which two different bridges link the copper and gadolinium ions. The structural determinations of a heterodinuclear Cu-Gd and a trinuclear Cu-Gd-Cu complex confirm the asymmetry of the central cores, involving phenoxo and hydroxo bridges. The magnetic studies evidence again the presence of ferromagnetic interactions. These results corroborate preponderance of the planarity of the Cu-O2-Gd core over the dissymmetry of the bridges. 相似文献
215.
Coulon Romain Broda Ryszard Cassette Philippe Courte Sammy Dupire Aldo Jerome Simon Judge Steven Kossert Karsten Liu Haoran Michotte Carine Nonis Manuel 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(8):3221-3230
Journal of Radioanalytical and Nuclear Chemistry - The Bureau International des Poids et Mesures (BIPM) is developing, with the support of national metrology institutes, an extension to the... 相似文献
216.
Dr. Nans Roques Anthony Tovar-Molle Dr. Carine Duhayon Dr. Stéphane Brandès Alex Spieß Prof. Dr. Christoph Janiak Dr. Jean-Pascal Sutter 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(61):e202201935
Five isostructural microporous supramolecular architectures prepared by H-bonded assembly between the hexa-anionic complex [Zr2(Ox)7]6− (Ox=oxalate, (C2O4)2−) and tripodal cations (H3-TripCH2-R)3+ with R=H, CH3, OH and OBn (Bn=CH2Ph) are reported. The possibility to obtain the same structure using a mixture of tripodal cations with different R group (R=OH and R=CH3) has also been successfully explored, providing a unique example of three-component H-bonded porous framework. The resulting SPA-1(R) materials feature 1D pores decorated by R groups, with apparent pore diameters ranging from 3.0 to 8.5 Å. Influence of R groups on the sorption properties of these materials is evidenced through CO2 and H2O vapor sorption/desorption experiments, as well as with I2 capture/release experiments in liquid media. This study is one of the first to demonstrate the possibility of tuning the porosity and exerting precise control over the chemical functionalization of the pores in a given H-bonded structure, without modifying the topology of the reference structure, and thus finely adjusting the sorption characteristics of the material. 相似文献
217.
The stereoselective acetylation of meso-2,2-dimethyl-1,3-cyclohexanediol by vinyl acetate in the presence of three lipases gave the (1R,3S)-monoester in high enantiomeric excess (ee > or = 98%). The hydrolysis of the corresponding meso-diacetate in the presence of Candida antarctica lipase in phosphate buffer provided the opposite enantiomer. Optically active monoacetates were converted to both enantiomers of 3-hydroxy-2,2-dimethylcyclohexanone, a versatile chiral building block. 相似文献
218.
Ruqaya Buhaibeh Oleg A. Filippov Antoine Bruneau‐Voisine Jrmy Willot Carine Duhayon Dmitry A. Valyaev Noël Lugan Yves Canac Jean‐Baptiste Sortais 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(20):6799-6803
Deprotonation of the MnI NHC‐phosphine complex fac‐[MnBr(CO)3(κ2P,C‐Ph2PCH2NHC)] ( 2 ) under a H2 atmosphere readily gives the hydride fac‐[MnH(CO)3(κ2P,C‐Ph2PCH2NHC)] ( 3 ) via the intermediacy of the highly reactive 18‐e NHC‐phosphinomethanide complex fac‐[Mn(CO)3(κ3P,C,C‐Ph2PCHNHC)] ( 6 a ). DFT calculations revealed that the preferred reaction mechanism involves the unsaturated 16‐e mangana‐substituted phosphonium ylide complex fac‐[Mn(CO)3(κ2P,C‐Ph2P=CHNHC)] ( 6 b ) as key intermediate able to activate H2 via a non‐classical mode of metal‐ligand cooperation implying a formal λ5‐P–λ3‐P phosphorus valence change. Complex 2 is shown to be one of the most efficient pre‐catalysts for ketone hydrogenation in the MnI series reported to date (TON up to 6200). 相似文献
219.
Dr. Ludmilla Guduff Dr. Patrick Berthault Dr. Carine van Heijenoort Dr. Jean-Nicolas Dumez Dr. Gaspard Huber 《Chemphyschem》2019,20(3):392-398
The analysis of complex mixtures of dissolved molecules is a major challenge, especially for systems that gradually evolve, e. g., in the course of a chemical reaction or in the case of chemical instability. 1D NMR is a fast and non-invasive method suitable for detailed molecular analysis, though of low sensitivity. Moreover, the spectral resolution of proton, the most commonly used and most sensitive stable isotope in NMR, is also quite limited. Spatially encoded (SPEN) experiments aim at creating in one acquisition a 2D data set by simultaneously performing different 1D sub-experiments on different slices of the NMR tube, at the price of an extra loss of sensitivity. Choosing translational diffusion coefficients as the additional dimension (the so-called DOSY approach) helps to recover proton spectra of each molecule in a mixture. The sensitivity limitation of SPEN NMR can, on the other hand, be addressed with hyperpolarization methods. Within hyperpolarization methods, signal amplification by reversible exchange (SABRE), based on parahydrogen, is the cheapest and the easiest one to set up, and allows multi-shot experiments. Here we show that the spectra of a mixture's components at millimolar concentration are resolved in few seconds by combining the SABRE, SPEN and DOSY concepts. 相似文献
220.
Delphine Veys-Renaux Richard Drevet Carine Petitjean Lionel Aranda Nicolas David Patrice Berthod 《Journal of Solid State Electrochemistry》2018,22(9):2821-2828
The electrochemical behavior of pure Co, pure Sb, and CoSb3 has been investigated over a large anodic potential range (0 to 40 V) in two acids, i.e., oxalic acid or sulfuric acid at different concentrations (0.01 to 1 M). Potentiodynamic polarizations performed on CoSb3 plates reveal the possible formation of a passive layer between 1 and 3 V (vs SCE), on a passivation plateau. The oxidation of CoSb3 at 2 V in sulfuric and oxalic acids results in the growth of an anodic conversion layer. This coating is mainly made of a porous layer of amorphous antimony oxides due to dealloying of CoSb3. In the specific case of oxalic acid, rods of crystallized oxalates are tangled between the oxide sheets. 相似文献