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61.
V. Gopalaswamy J. A. Rice F. G. Miller 《The Journal of the Operational Research Society》1993,44(1):37-50
In recent years much emphasis has been placed on maintenance of transit vehicles. This is due to many reasons: inflation, availability of vehicles for maintenance, reliability of components etc. Many mathematical models have been developed to predict the replacement mileage of the components. These models usually focus on only one criterion for decision-making, namely the minimum replacement cost-rate. This concept tends to oversimplify the situation that is present in the system. In this research, mathematical models were developed for three criteria: (1) minimum replacement cost-rate, (2) maximum availability and (3) bottom-line component reliability. Optimum replacement plans were obtained using different multiple-criteria decision-making methods like Strictest Selection, Lexicographic and Waltz Lexicographic methods. 相似文献
62.
M. Capizzi G.A. Thomas F. DeRosa R.N. Bhatt T.M. Rice 《Solid State Communications》1979,31(9):611-616
Far-infrared transmission measurements on P-doped Si at donor concentrations below the metal-insulator transition show absorption bands from donor pairs. We identify the lowest energy band as charge transfer excitations from a donor to its neigbhor, forming excitons (D+D-) in the Mott-Hubbard gap. The results suggest that charge transfer states in complexes dominate the low-energy optical excitations as the insulator approaches the Mott density. 相似文献
63.
M.J. Rice 《Solid State Communications》1978,25(12):1083-1086
The amplitude and phase phonons and the frequency dependent conductivity below the mean-field Peierls-Fröhlich transition temperature Tc, and the Kohn anomaly and fluctuation induced charge-density-wave conductivity above Tc, are discussed on the basis of the many-phonon-coupling model recently introduced by Rice, Duke and Lipari. For dominant intramolecular phonon coupling an isotope effect in Tc is related to the isotopic shift in the small polaron binding energy. 相似文献
64.
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66.
Enhancing sonochemical activity in aqueous media using power-modulated pulsed ultrasound: an initial study 总被引:1,自引:0,他引:1
Relatively little is known about the effects of pulsed ultrasound on the facilitation of chemical reactivity. Previous studies have indicated that sonochemistry using pulses is generally less effective than continuous ultrasonic irradiation. However, the pulse trains employed were such that the peak power of the pulses was the same as the maximum power used in continuous irradiation. As a result, less acoustic energy was transmitted to the solutions over the same period of time. The effectiveness of ultrasound when the pulse is adjusted so that the same amount of acoustic energy is input compared to continuous irradiation over a given time has not been previously explored. In this study we have embarked on an examination of the efficacy of power-modulated pulsed (PMP) sonochemistry. Specifically, we have explored the effects of pulse type and pulse frequency on the oxidation of potassium iodide and the degradation of acid orange, a common industrial colorant. A rate increase by a factor of three was observed compared with continuous irradiation under conditions of equivalent acoustic input power. 相似文献
67.
Mast TD Makin IR Faidi W Runk MM Barthe PG Slayton MH 《The Journal of the Acoustical Society of America》2005,118(4):2715-2724
Methods for the bulk ablation of soft tissue using intense ultrasound, with potential applications in the thermal treatment of focal tumors, are presented. An approximate analytic model for bulk ablation predicts the progress of ablation based on tissue properties, spatially averaged ultrasonic heat deposition, and perfusion. The approximate model allows the prediction of threshold acoustic powers required for ablation in vivo as well as the comparison of cases with different starting temperatures and perfusion characteristics, such as typical in vivo and ex vivo experiments. In a full three-dimensional numerical model, heat deposition from array transducers is computed using the Fresnel approximation and heat transfer in tissue is computed by finite differences, accounting for heating changes caused by boiling and thermal dose-dependent absorption. Similar ablation trends due to perfusion effects are predicted by both the simple analytic model and the full numerical model. Comparisons with experimental results show the efficacy of both models in predicting tissue ablation effects. Phenomena illustrated by the simulations and experiments include power thresholds for in vivo ablation, differences between in vivo and ex vivo lesioning for comparable source conditions, the effect of tissue boiling and absorption changes on ablation depth, and the performance of a continuous rotational scanning method suitable for interstitial bulk ablation of soft tissue. 相似文献
68.
We investigate the quantum fluctuations of a single atom in a weakly driven cavity, where the center of mass motion of the atom is quantized in one dimension. We present analytic results for the second order intensity correlation function g((2))(tau) and the intensity-field correlation function h(theta)(tau), for transmitted light in the weak driving field limit. We find that the coupling of the center of mass motion to the intracavity field mode can be deleterious to nonclassical effects in photon statistics and field-intensity correlations, and compare the use of trapped atoms in a cavity to atomic beams. 相似文献
69.
This report describes the first hydrophobic nitric oxide (NO)-releasing material that utilizes light as an external on/off trigger to control the flux of NO generated from cured polymer films. Fumed silica polymer filler particles were derivatized with S-nitroso-N-acetyl-dl-penicillamine and blended into the center layer of trilayer silicone rubber films. Nitric oxide is generated upon irradiation with light, and fluxes increase with increasing power of incident light. The ability to precisely control NO generation from this material has the potential to answer fundamental questions about the levels of NO needed to achieve desired therapeutic affects in different biomedical applications. 相似文献
70.
Hashimoto A Przybyl AK Linders JT Kodato S Tian X Deschamps JR George C Flippen-Anderson JL Jacobson AE Rice KC 《The Journal of organic chemistry》2004,69(16):5322-5327
The synthesis of the ortho- and para-e isomers in the oxide-bridged 5-phenylmorphan series of rigid tetracyclic compounds was accomplished via rac-5-(2-fluoro-5-nitrophenyl)-2-methyl-2-azabicyclo[3.3.1]nonan-9beta-ol ((+/-)-10), an intermediate containing an aromatic nitro-activated fluorine atom. The fluorine atom was used as the leaving group for the formation of the strained tetracyclic trans-fused 5,6-ring system in rac-(1alpha,4aalpha,9aalpha)-1,3,4,9a-tetrahydro-2-methyl-6-nitro-2H-1,4a-propanobenzofuro[2,3-c]pyridine ((+/-)-11), although preference for cis ring fusion during the formation of tricyclic tetra- and hexahydrodibenzofurans has been well-documented. Single-crystal X-ray crystallographic study of the desired para-e isomer ((+/-)-2), as well as of two intermediates in its synthesis, provided assurance of the correct structures. The e-isomers are among the last of the 12 oxide-bridged 5-phenylmorphans to be synthesized. We envisioned the syntheses of these rigid, tetracyclic compounds in order to determine the three-dimensional pattern of a ligand that would enable interaction with opioid receptors as agonists or antagonists. 相似文献