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101.
Delphine Prvot Christophe Galliot Anne-Marie Caminade Jean Pierre Majoral 《Heteroatom Chemistry》1995,6(4):313-318
Phosphorus dialdehydes RP (OC6H4CHO)2 (R = Ph, Me2N) react with phosphodihydrazides PhP(Y)-[N(CH3)NH2]2 (Y = S, O) to give macrocycles 6a–c arising from [2 + 2] cyclocondensation reactions. Treatment of phosphodihydrazone PhP(S) [OC6H4CH N–N(Me)H]2 7 with phenyldichlorophosphine affords macrocycle 8 possessing tri and tetracoordinated phosphorus atoms. Clean desulfurization of thiophosphorus macrocycles 9 and 12 gives rise selectively to new tricoordinated phosphorus containing macrocycles 11 and 13 . 相似文献
102.
Aude Marjolin Christophe Gourlaouen Carine Clavaguéra Pengyu Y. Ren Johnny C. Wu Nohad Gresh Jean-Pierre Dognon Jean-Philip Piquemal 《Theoretical chemistry accounts》2012,131(4):1198
In this contribution, we focused on the use of polarizable force fields to model the structural, energetic, and thermodynamical
properties of lanthanides and actinides in water. In a first part, we chose the particular case of the Th(IV) cation to demonstrate
the capabilities of the AMOEBA polarizable force field to reproduce both reference ab initio gas-phase energetics and experimental
data including coordination numbers and radial distribution functions. Using such model, we predicted the first polarizable
force field estimate of Th(IV) solvation free energy, which accounts for −1,638 kcal/mol. In addition, we proposed in a second
part of this work a full extension of the SIBFA (Sum of Interaction Between Fragments Ab initio computed) polarizable potential
to lanthanides (La(III) and Lu(III)) and to actinides (Th(IV)) in water. We demonstrate its capabilities to reproduce all
ab initio contributions as extracted from energy decomposition analysis computations, including many-body charge transfer
and discussed its applicability to extended molecular dynamics and its parametrization on high-level post-Hartree–Fock data. 相似文献
103.
Bui TT Iordache A Chen Z Roznyatovskiy VV Saint-Aman E Lim JM Lee BS Ghosh S Moutet JC Sessler JL Kim D Bucher C 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(19):5853-5859
A new member of the cyclo[n]pyrrole class of expanded porphyrins could be prepared from the corresponding thiophene-containing terpyrrole precursor through use of a mild electrochemical oxidative procedure. The isolated macrocycle, featuring nine heterocyclic subunits directly connected through their α,α'-positions, is the largest cyclo[n]pyrrole derivative reported to date (see figure). 相似文献
104.
A three step synthesis of various thiobarbiturate derivatives 17-24 was established. The first step is mediated by Mn(OAc)?, in order to generate a carbon-carbon bond between a terminal alkene and malonate. Derivatives 1-8 were obtained in moderate to good yields under mild conditions. This key step allows synthesis of a wide variety of lipophilic thiobarbiturates, which could be tested for their anticonvulsive or anesthesic potential. 相似文献
105.
Poumale HM Awoussong KP Randrianasolo R Simo CC Ngadjui BT Shiono Y 《Natural product research》2012,26(8):749-755
In addition to lupeol (1a), three long-chain alkanoic acid esters of lupeol, in which two were new, were isolated from the hexane and ethyl acetate twigs extract of Dorstenia harmsiana Engl. (Moraceae). The structures of the new compounds were elucidated on the basis of 1D and 2D NMR experiments. Some isolated compounds were evaluated for their antimicrobial activities. The lupeol and its three long-chain alkanoic acid esters showed antifungal and antibacterial activities. 相似文献
106.
Urchaga P Baranton S Coutanceau C Jerkiewicz G 《Langmuir : the ACS journal of surfaces and colloids》2012,28(7):3658-3663
An understanding of the oxidation of chemisorbed CO (CO(chem)) on Pt nanoparticle surfaces is of major importance to fuel cell technology. Here, we report on the relation between Pt nanoparticle surface structure and CO(chem) oxidative stripping behavior. Oxidative stripping voltammograms are obtained for CO(chem) preadsorbed on cubic, octahedral, and cuboctahedral Pt nanoparticles that possess preferentially oriented and atomically flat domains. They are compared to those obtained for etched and thermally treated Pt(poly) electrodes that possess atomically flat, ordered surface domains separated by grain boundaries as well as those obtained for spherical Pt nanoparticles. A detailed analysis of the results reveals for the first time the presence of up to four voltammetric features in CO(chem) oxidative stripping transients, a prepeak and three peaks, that are assigned to the presence of surface domains that are either preferentially oriented or disordered. The interpretation reported in this article allows one to explain all features within the voltammograms for CO(chem) oxidative stripping unambiguously. 相似文献
107.
Zagdoun A Casano G Ouari O Lapadula G Rossini AJ Lelli M Baffert M Gajan D Veyre L Maas WE Rosay M Weber RT Thieuleux C Coperet C Lesage A Tordo P Emsley L 《Journal of the American Chemical Society》2012,134(4):2284-2291
A new nitroxide-based biradical having a long electron spin-lattice relaxation time (T(1e)) has been developed as an exogenous polarization source for DNP solid-state NMR experiments. The performance of this new biradical is demonstrated on hybrid silica-based mesostructured materials impregnated with 1,1,2,2-tetrachloroethane radical containing solutions, as well as in frozen bulk solutions, yielding DNP enhancement factors (ε) of over 100 at a magnetic field of 9.4 T and sample temperatures of ~100 K. The effects of radical concentration on the DNP enhancement factors and on the overall sensitivity enhancements (Σ(?)) are reported. The relatively high DNP efficiency of the biradical is attributed to an increased T(1e), which enables more effective saturation of the electron resonance. This new biradical is shown to outperform the polarizing agents used so far in DNP surface-enhanced NMR spectroscopy of materials, yielding a 113-fold increase in overall sensitivity for silicon-29 CPMAS spectra as compared to conventional NMR experiments at room temperature. This results in a reduction in experimental times by a factor >12,700, making the acquisition of (13)C and (15)N one- and two-dimensional NMR spectra at natural isotopic abundance rapid (hours). It has been used here to monitor a series of chemical reactions carried out on the surface functionalities of a hybrid organic-silica material. 相似文献
108.
Volkringer C Henry N Grandjean S Loiseau T 《Journal of the American Chemical Society》2012,134(2):1275-1283
A series of uranyl and lanthanide (trivalent Ce, Nd) mellitates (mel) has been hydrothermally synthesized in aqueous solvent. Mixtures of these 4f and 5f elements also revealed the formation of a rare case of lanthanide-uranyl coordination polymers. Their structures, determined by XRD single-crystal analysis, exhibit three distinct architectures. The pure lanthanide mellitate Ln(2)(H(2)O)(6)(mel) possesses a 3D framework built up from the connection of isolated LnO(6)(H(2)O)(3) polyhedra (tricapped trigonal prism) through the mellitate ligand. The structure of the uranyl mellitate (UO(2))(3)(H(2)O)(6)(mel)·11.5H(2)O is lamellar and consists of 8-fold coordinated uranium atoms linked to each other through the organic ligand giving rise to the formation of a 2D 3(6) net. The third structural type, (UO(2))(2)Ln(OH)(H(2)O)(3)(mel)·2.5H(2)O, involves direct oxygen bondings between the lanthanide and uranyl centers, with the isolation of a heterometallic dinuclear motif. The 9-fold coordinated Ln cation, LnO(5)(OH)(H(2)O)(3), is linked to the 7-fold coordinated uranyl (UO(2))O(4)(OH) (pentagonal bipyramid) via one μ(2)-hydroxo group and one μ(2)-oxo group. The latter is shared between the uranyl bonding (U═O = 1.777(4)/1.779(6) ?) and a long Ln-O bonding (Ce-O = 2.822(4) ?; Nd-O = 2.792(6) ?). This unusual linkage is a unique illustration of the so-called cation-cation interaction associating 4f and 5f metals. The dinuclear motif is then further connected through the mellitate ligand, and this generates organic-inorganic layers that are linked to each other via discrete uranyl (UO(2))O(4) units (square bipyramid), which ensure the three-dimensional cohesion of the structure. The mixed U-Ln carboxylate is thermally decomposed from 260 to 280 °C and then transformed into the basic uranium oxide (U(3)O(8)) together with U-Ln oxide with the fluorite structural type ("(Ln,U)O(2)"). At 1400 °C, only fluorite type "(Ln,U)O(2)" is formed with the measured stoichiometry of U(0.63)Ce(0.37)O(2) and U(0.60)Nd(0.40)O(2-δ). 相似文献
109.
We describe the unique structural and electronic arrangement in the heptanuclear polyiodobismuthate [Bi(7)I(24)](3-) which displays striking similarities with the Anderson-type structures found in polyoxometalates. This main group element anion is part of the complex [Bi(OAc)(2)(thf)(4)](3)[Bi(7)I(24)] (1) which has been characterized by X-ray crystallography. We investigated the structure, stability, and bonding of [Bi(7)I(24)](3-) using relativistic dispersion-corrected density functional theory in combination with a quantitative energy decomposition and electron localization function analysis in order to better understand the main features of this isopolyanion. A comparative analysis of the properties of [Bi(7)I(24)](3-) and previously reported high-nuclearity [Bi(n)X(3n+m)](m-) anions, in the gas phase and in solution, has been performed, in the latter case to track the macroscopic solvent effects. [Bi(7)I(24)](3-) is the largest building block in the class of trianionic iodobismuthates and the sole heptanuclear framework in the family of iodobismuthates. 相似文献
110.
C Dussouy L Bultel J Saguez A Cherqui M Khelifa E Grand P Giordanengo J Kovensky 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(32):10021-10028
The synthesis of four GlcNAc(β1→4)Glc disaccharides containing 2-O-acetyl and/or 6-sulfate groups was performed in high yields with total 1,2-trans stereoselectivity. These disaccharides were evaluated as candidates for insect chitinase inhibition and aphicidal activity. All the compounds prepared displayed physiological effects on M. persicae aphids; however, the inhibition of chitinases of different sources (bacteria, fungus, and aphid) followed different patterns according to subtle structural characteristics. 相似文献