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61.
Umesh V. Waghmare 《Journal of Chemical Sciences》2003,115(5-6):439-446
We study structure and magnetic properties of La0.5Ba0.5CoO3(LBGO) usingab initio density functional theory (DFT) method based on pseudopotentials and a plane-wave basis. We find the cubic structure of LBCO
is ferromagnetic and lower in energy than the nonmagnetic rhombohedral structure. Through the calculation of Γ-point phonons
of LBCO in the cubic structure, we determine its structural instabilities and find that they correspond to the structural
phase transition accompanying a para-ferromagnetic transition observed recently.
Dedicated to Professor C N R Rao on his 70th birthday 相似文献
62.
Summary Nitrosyltribromide reacts with rhodium(I) complexes and with rhodiumtrichloride trihydrate in the presence of triphenylphosphine and triphenylarsine to give rhodium(III) nitrosyl complexes and rhodium(III) hyponitrite complexes which are characterized by i.r. spectra, magnetic measurements and by elemental analyses. 相似文献
63.
Abstract— Both the UV- and y-radiation survival curves of Micrococcus radiophilus are distinguished by large shoulders. However, a combination radiation treatment results in an enhanced killing effect. Pre-UV treatment is found to give a synergistic kill as compared to an additive kill when the sequence of radiation treatments is reversed. 相似文献
64.
Symmetries, vibrational instabilities, and routes to stable structures of clusters of Al, Sn, and As 总被引:2,自引:0,他引:2
We investigate the stability of small clusters using density functional theory to compute the total energy, forces, and vibrational frequencies using linear response. We exhibit an efficient and computationally low-cost route to finding stable structures, by starting with high-symmetry structures and distorting them according to their unstable modes. We illustrate this by application to 4-, 6-, and 13-atom clusters of Al, Sn, and As. This technique also naturally elucidates the origins of stability of the lower symmetry structures, which is variously due to the linear or pseudo Jahn-Teller effect, combined with a lowering of various contributions to the total energy. We show that the situation is more complex than has generally been appreciated. 相似文献
65.
66.
67.
Seema Pant Priyanka Sharma Umesh C. Pant 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):2974-2983
Six 5-substituted-2-aminobenzenethiols have been reacted with 3-(2-chlorophenyl)-1-(4-chlorophenyl)-2-propenone and 3-(2-chlorophenyl)-1-(2-thienyl)-2-propenone in dry ethanol saturated with dry HCl gas, to obtain twelve new compounds, 8-substituted-2-(2-chlorophenyl)-4-(4-chlorophenyl/2-thienyl)-2,5-dihydro-1,5-benzothiazepines in satisfactory yields. The structures of the final products have been assigned by elemental microanalyses data for elements, C, H, and N and by IR, 1 H NMR, and mass spectroscopies. The synthesized compounds have been evaluated for their relative antimicrobial activity against the gram-positive bacteria, Staphylococcus aureus, gram-negative bacteria, Pseudomonas aeruginosa and the fungus, Candida albicans. The compounds have been found to show little antibacterial activity, but interestingly, showed significant antifungal activity. 相似文献
68.
A novel approach for the synthesis of a bird-shaped bis-triquinane 3, a fascinating carbocyclic framework closely related to the skeleton of Xeromphalinone E 1 from readily available 2,6-dimethyl phenol 8 has been reported. The synthesis of bis-cyclohexadienones 6, 22a–e by oxidative acetylation of tetramethyl bisphenols 7, 20a–e has been investigated using two different reagents under varying reaction conditions. The cycloaddition of bis-cyclohexadienone 6 gives two carbocycles, bis-adduct 4b and mono-adduct 5d in a stereocontrolled manner. The photochemical sigmatropic 1,2-acyl shift in 4b furnished 3 and monotriquinane 9 linked with a 9-acetoxy-9-methyl-endo-tricyclo[5,2,2,02,6]undeca-4,10-diene-8-one system. Two different pentasubstituted phenols 13 and 14 were also isolated during an attempted oxa-di-π-methane (ODPM) rearrangement of mono-adduct 5d via aromatisation of the cyclohexadienone ring. The photochemical behaviour of bis-cyclohexadienones 6, 22a–e has also been investigated under UV irradiation and two different aromatized products were isolated for each bis-cyclohexadienone by migration and elimination of acetate groups. 相似文献
69.
Umesh B. Kosurkar Tulshiram L. Dadmal K. Appalanaidu Y. Khageswara Rao Jagadeesh B. Nanubolu Ravindra M. Kumbhare 《Tetrahedron letters》2014
A highly, efficient synthetic protocol for the synthesis of 2-aminooxazolo[4,5-b]pyridine derivatives is established via intramolecular C–O bond coupling using copper iodide as a catalyst and water as solvent. A variety of functionalized substrates were found to react under this reaction conditions to provide products in good to excellent yields. 相似文献
70.
The molecular charge complex urea picrate (UP) was synthesized and its third order nonlinear optical properties have been investigated using a single beam Z-scan technique with nanosecond laser pulses at 532 nm. Open aperture data of the compound indicates two photon absorption at this wavelength. The nonlinear refractive index n2, nonlinear absorption coefficient β, magnitude of effective third order susceptibility χ(3), the second order hyperpolarizability γh and the coupling factor ρ have been estimated. The experimentally determined values of β, n2, Re χ(3) and Im χ(3), γh and ρ of the compound UP are 2.146 cm/GW, −1.258×10−11 esu, −1.347×10−13 esu, 0.377×10−13 esu, 0.69×10−32 esu and 0.28, respectively. The compound exhibits good optical limiting at 532 nm with the limiting threshold of 80 μJ/pulse. Our studies suggest that compound UP is a potential candidate for optical device applications such as optical limiters. 相似文献