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71.
Hou GL Wen H Lopata K Zheng WJ Kowalski K Govind N Wang XB Xantheas SS 《Angewandte Chemie (International ed. in English)》2012,51(26):6356-6360
Shining light on Zeise: In a study of Zeise's anion, [PtCl(3)(C(2)H(4))](-), and its bromine and iodine analogues, electronic structure information for each species, derived from spectral features, is assigned through calculations at the coupled cluster level of theory. The calculations indicate that the electron binding energies decrease with halogen size and that there is a synergistic η(2) interaction between C(2)H(4) and the PtX(3)(-) anions. 相似文献
72.
Papavassiliou G Pissas M Diamantopoulos G Belesi M Fardis M Stamopoulos D Kontos AG Hennion M Dolinsek J Ansermet JP Dimitropoulos C 《Physical review letters》2006,96(9):097201
By using nuclear magnetic resonance techniques we show that for T<30 K the La0.875Sr0.125MnO3 compound displays a nonuniform charge distribution, comprised of two interconnected Mn ion subsystems with different spin, orbital, and charge couplings. The NMR results agree very well with the two spin wave stiffness constants observed at small q values in the spin wave dispersion curves [Phys. Rev. B 67, 214430 (2003)]. This picture is probably related to a yet undetermined charge and orbital superstructure occurring in the ferromagnetic insulating state of the La0.875Sr0.125MnO3 compound. 相似文献
73.
74.
We present a revision of the flexible, polarizable, Thole-type interaction potential for water [J. Chem. Phys.2002, 116, 5115], which allows for condensed-phase simulations. The revised version (TTM2.1-F) of the potential correctly describes the individual water molecular dipole moment and alleviates problems arising at short intermolecular separations that can be sampled in the course of molecular dynamics and Monte Carlo simulations of condensed environments. Furthermore, its parallel implementation under periodic boundary conditions enables the efficient calculation of the macroscopic structural and thermodynamic properties of liquid water, as its performance scales superlinearly with up to a number of 64 processors for a simulation box of 512 molecules. We report the radial distribution functions, average energy, internal geometry, and dipole moment in the liquid as well as the density, dielectric constant, and self-diffusion coefficient at T = 300 K from (NVT) and (NPT) classical molecular dynamics simulations by using the revised version of the potential. 相似文献
75.
We examine theoretically the three channels that are associated with the detachment of a single water molecule from the aqueous clusters of the alkaline earth dications, [M(H2O) n ]2+, M = Mg, Ca, Sr, Ba, n ≤ 6. These are the unimolecular water loss (M2+(H2O) n?1 + H2O) and the two hydrolysis channels resulting the loss of hydronium ([MOH(H2O) n?2]+ + H3O+) and Zundel ([MOH(H2O) n?3]+ + H3O+(H2O)) cations. Minimum energy paths (MEPs) corresponding to those three channels were constructed at the Møller–Plesset second order perturbation (MP2) level of theory with basis sets of double- and triple-ζ quality. We furthermore investigated the water and hydronium loss channels from the mono-hydroxide water clusters with up to four water molecules, [MOH(H2O) n ]+, 1 ≤ n ≤ 4. Our results indicate the preference of the hydronium loss and possibly the Zundel-cation loss channels for the smallest size clusters, whereas the unimolecular water loss channel is preferred for the larger ones as well as the mono-hydroxide clusters. Although the charge separation (hydronium and Zundel-cation loss) channels produce more stable products when compared to the ones for the unimolecular water loss, they also require the surmounting of high-energy barriers, a fact that makes the experimental observation of fragments related to these hydrolysis channels difficult. 相似文献
76.
Manolis A. Fousteris Anna I. Koutsourea Sotiris S. Nikolaropoulos Abdelkhalek Riahi Jacques Muzart 《Journal of molecular catalysis. A, Chemical》2006,250(1-2):70-74
Various chromiumVI-catalyzed conditions have been tested to improve the oxidation of Δ5-steroids with t-BuOOH to their corresponding 5-en-7-ones. The use of PDC or the association of CrO3 with an amine as the catalyst and CH2Cl2 or PhCF3 as the solvent led usually to the best yields. A minor reaction pathway was the epoxidation of the double bond. 相似文献
77.
Dimitra Kovala‐Demertzi Aglaia Koutsodimou Angeliki Galani Sotiris K. Hadjikakou Mavroudis A. Demertzis Marianna Xanthopoulou John R. Miller Christopher S. Frampton 《应用有机金属化学》2004,18(9):501-502
The crystal structure of complex [Ph2Sn(Hpir)2 ·CH3CN] shows for the first time chelation to a metal atom of piroxicam through the keto‐enolate oxygen atoms. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
78.
The melting temperature (T(m)) of liquid water with the Becke-Lee-Yang-Parr (BLYP) density functional including dispersion corrections (BLYP-D) and the Thole-type, version 3 (TTM3-F) ab-initio based flexible, polarizable classical potential is reported via constant pressure and constant enthalpy (NPH) molecular dynamics simulations of an ice I(h)-liquid coexisting system. Dispersion corrections to BLYP lower T(m) to about 360 K, a large improvement over the value of T(m) > 400 K previously obtained with the original BLYP functional under the same simulation conditions. For TTM3-F, T(m) = 248 K from classical molecular dynamics simulations. 相似文献
79.
Quantum chemical calculations at the CASSCF level of theory on the O3‐homologous molecules CX22‐, NX2‐, X3, OX2, and FX2+ (X: O, S, Se, Te, Po) indicate that the triatomic inorganic biradicals in the FX2+ series have unusually high biradical character. 相似文献
80.
Reductions of peak-to-average power ratio and optical beat interference in cost-effective OFDMA-PONs
A. Tsokanos E. Giacoumidis G. Zardas A. Kavatzikidis N. P. Diamantopoulos I. Aldaya I. Tomkos 《Photonic Network Communications》2013,26(2-3):44-52
The peak-to-average power ratio (PAPR) and optical beat interference (OBI) effects are examined thoroughly in orthogonal frequency-division multiplexing access (OFDMA)-passive optical networks (PONs) at a signal bit rate up to $\sim 20\,\mathrm{{Gb}}/{\hbox {s}}$ per channel using cost-effective intensity-modulation and direct-detection (IM/DD). Single-channel OOFDM and upstream multichannel OFDM-PONs are investigated for up to six users. A number of techniques for mitigating the PAPR and OBI effects are presented and evaluated including adaptive-loading algorithms such as bit/power-loading, clipping for PAPR reduction, and thermal detuning (TD) for the OBI suppression. It is shown that the bit-loading algorithm is a very efficient PAPR reduction technique by reducing it at about 1.2 dB over 100 Km of transmission. It is also revealed that the optimum method for suppressing the OBI is the TD + bit-loading. For a targeted BER of $1 \times 10 ^{-3}$ , the minimum allowed channel spacing is 11 GHz when employing six users. 相似文献