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991.
Edwin C. Constable Catherine E. Housecroft Benson M. Kariuki Christopher B. Smith 《Supramolecular chemistry》2013,25(4):305-309
We have prepared two new 2,2′-bipyridine ligands bearing 3-aryl substituents at the 5 and 5′-positions using Suzuki methodology. The substituents differ only in the presence of a methoxy group or a phenolic hydroxy group. In the solid state a beautiful self-complementary hydrogen-bonded lattice incorporating one water molecule per ligand is formed with the phenolic compound. 相似文献
992.
Leonard J. Harbour Susan A. Bourne Mino R. Caira Luigi R. Nassimbeni Edwin Weber Konstantinos Skobridis 《Supramolecular chemistry》2013,25(3-4):331-336
Abstract The structures of the inclusion compounds of 2,2′-bis(9-hydroxy-9-fluorenyl)biphenyl (H) with acetonitrile (1) (1:1), cyclohexanone (2) (1:2), di-n-propylamine (3) (1:1) and dimethylformamide (4) (1:2) are reported. Crystal data: (1) monoclinic, P21/c with a=10.500(3), b=15.598(3), c=18.344(3) Å, β=96.66(2)°, Z=4, D C=1.24 g cm?3. (2) monoclinic, P21/c with a=13.980(3), b=11.768(5), c=23.49(1) Å, β=98.77(3)°, Z=4, Dc =1.24 g cm?3. (3) monoclinic, C2/c with a=29.57(1), b=13.485(4), c=18.17(1) Å, β=107.94(4)°, Z=8, D C=1.16 g cm?3. (4) monoclinic, C2/c with a=30.123(9), b=13.391(6), c=19.177(6) Å, β=111.23(4)°, Z=8, D C=1.22 g cm?3. Final R values for the four structures were 0.065, 0.120, 0.084 and 0.107 for 2937, 2830, 2071 and 3769 reflections, respectively. The host conformation is quite rigid and does not appear to be influenced by the shape and size of the guests studied. The host is held in a spiral conformation by means of an intramolecular hydrogen bond. In addition, host-guest hydrogen bonds are observed in all structures. Thermal analysis was used to evaluate the strength of binding of the guest molecules and confirmed that (1) is the most stable of the four compounds studied. 相似文献
993.
The stochastic equation of motion for a heaving cylinder subject to irregular sea waves is solved numerically with the polynomial chaos framework. Thereby, the stochastic forcing is expressed by a truncated Karhunen-Loève expansion and the hydrodynamic radiation is formulated as a state space model. We obtain the mean and the variance of the cylinder heave motion. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
994.
We study the f (R)-Maxwell black hole imposed by constant curvature and its all thermodynamic quantities, which may lead to the Reissner-Nordström-AdS black hole by redefining Newtonian constant and charge. Further, we obtain the f (R)-Yang-Mills black hole imposed by constant curvature, which is related to the Einstein-Yang-Mills black hole in AdS space. Since there is no analytic black hole solution in the presence of Yang-Mills field, we obtain asymptotic solutions. Then, we confirm the presence of these solutions in a numerical way. 相似文献
995.
A new synthesis of the cylindrocarine group of alkaloids 总被引:1,自引:0,他引:1
The Kuehne synthesis of anilinoacrylate alkaloids has been adapted to afford a new synthesis of (±)-12-demethoxy-N-acetylcylindrocarine, (±)-cylindrocarine, and (±)-N-formylcylindrocarine. 相似文献
996.
Edwin Alvarado Anna C. Badaj Timothy G. Larocque Prof. Dr. Gino G. Lavoie 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(38):12112-12121
Gold(I) complexes of 1‐[1‐(2,6‐dimethylphenylimino)alkyl]‐3‐(mesityl)imidazol‐2‐ylidene (C^ImineR), 1,3‐dimesitylimidazol‐2‐ylidene (IMes) and of the corresponding thione derivatives (S^ImineR and IMesS) were prepared and structurally characterised. The solid‐state structure of the C^ImineR and S^ImineR gold(I) complexes showed monodentate coordination of the ligand and a dangling imine group that could bind reversibly to the metal centre to stabilise otherwise unstable catalytic intermediates. Interestingly, reaction of C^IminetBu with [AuCl(SMe2)] led to the formation of [(C^IminetBu)AuCl], which rearranges upon crystallisation into the unusual complex cation [(C^IminetBu)2Au]+, with AuCl2? as the counterion. The activity of the gold complexes in the hydroamination of phenylacetylene with substituted anilines was tested and compared to control catalyst systems. The best catalytic performance was obtained with [(C^IminetBu)AuCl], with the exclusive formation of the Markovnikov addition product in excellent yield (>95 %) regardless of the substituents on aniline. 相似文献
997.
Joana L. A. Miranda Raquel B. R. Mesquita Edwin Palacio Jos M. Estela Víctor Cerd Antnio O. S. S. Rangel 《Molecules (Basel, Switzerland)》2022,27(4)
In this work, a flow-based spectrofluorimetric method for iodine determination was developed. The system consisted of a miniaturized chip-based flow manifold for solutions handling and with integrated spectrofluorimetric detection. A multi-syringe module was used as a liquid driver. Iodide was quantified from its catalytic effect on the redox reaction between Ce(IV) and As(III), based on the Sandell–Kolthoff reaction. The method was applied for the determination of iodine in salt, pharmaceuticals, supplement pills, and seaweed samples without off-line pre-treatment. An in-line oxidation process, aided by UV radiation, was implemented to analyse some samples (supplement pills and seaweed samples) to eliminate interferences and release iodine from organo-iodine compounds. This feature, combined with the fluorometric reaction, makes this method simpler, faster, and more sensitive than the classic approach of the Sandell–Kolthoff reaction. The method allowed iodine to be determined within a range of 0.20–4.0 µmol L−1, with or without the in-line UV digestion, with a limit of detection of 0.028 µmol L−1 and 0.025 µmol L−1, respectively. 相似文献
998.
Edwin C. Constable Catherine E. Housecroft Valrie Jullien Markus Neuburger Ingo Poleschak Sbastien Reymann Sina Saxer Silvia Schaffner 《Polyhedron》2007,26(18):5519-5526
The chiral ligands, 4,4′-bis{(1S,2R,4S)-(−)-bornyloxy}-2,2′-bipyridine, (1S,2R,4S)-1, and 4,4′-bis{(1R,2S,4R)-(+)-bornyloxy}-2,2′-bipyridine, (1R,2S,4R)-1, have been prepared and characterized by spectroscopic techniques and, for (1S,2R,4S)-1, by single crystal X-ray diffraction. Despite the use of enantiomerically pure ligands, the formation of the complexes [Fe((1S,2R,4S)-1)3]2+, [Ru((1S,2R,4S)-1)3]2+, [Ru((1S,2R,4S)-1)(bpy)2]2+ and [Ru((1R,2S,4R)-1)(bpy)2]2+ proceeds without preference for either the Δ or Λ-diastereoisomers. 相似文献
999.
Juarez Vicente Leandro Pereira Cappato Verônica Maria de Araújo Calado Mario Geraldo de Carvalho Edwin Elard Garcia-Rojas 《Journal of Thermal Analysis and Calorimetry》2018,131(3):2093-2104
The oxidative stability of edible oils is an important feature to know due the undesirable changes that can occur in the storage. In this way, the oxidative induction time (OIT) value is an indicative to prevent this effect. The objectives of this study were to evaluate the omega-3 content and kinetic parameters of Sacha Inchi oil (SIO) and capsules that are formed with biopolymers, in addition, there were analyzed with differential scanning calorimetry (DSC) and proton nuclear magnetic resonance (1H NMR). The SIO and capsules, formed using an emulsion, were analyzed with DSC in an oxygen atmosphere to determine the OIT value in isothermal conditions at 100, 120 and 150 °C. The kinetic parameters (activation energy, pre-exponential factor and z value) of SIO were obtained, and the stability time was predicted at different temperatures. The 1H NMR spectra enabled us to assess the identification and percentage relative before and after the isothermal DSC oxidation of omega-3 concentration and formation of their oxidized compounds. (E-E)-2,4-Alkadienals were the primary oxidized compound and is strongly correlated with the decrease in omega-3 content. Isothermal DSC is a useful to determine the OIT (min) and kinetic parameters to predict the stability oxidation in different edible oils and thus prevent the inadequate consumption of edible oils oxidized. 相似文献
1000.