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1.
DongXiangLI WanGuoHOU ShuPingLI MingTuHAO GaoYongZHANG 《中国化学快报》2004,15(2):224-227
The relation of the isoelectric point (IEP) and the point of zero net charge (PZNC) of the hydrotalcite-like compounds was discussed. It was found that the IEP does not equal to the PZNC and the IEP is higher than the PZNC. The structural positive charges existing in the HTlc,which cause the difference between the IEP and the PZNC. The effects of the structural positive charges of the HTlc on its IEP and PZNC are the same as the specific adsorption of metal cations. 相似文献
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Abdurashitov JN Gavrin VN Girin SV Gorbachev VV Ibragimova TV Kalikhov AV Khairnasov NG Knodel TV Kornoukhov VN Mirmov IN Shikhin AA Veretenkin EP Vermul VM Yants VE Zatsepin GT Bowles TJ Nico JS Teasdale WA Wark DL Cherry ML Karaulov VN Levitin VL Maev VI Nazarenko PI Shkol'nik VS Skorikov NV Cleveland BT Daily T Davis R Lande K Lee CK Wildenhain PW Khomyakov YS Zvonarev AV Elliott SR Wilkerson JF 《Physical review letters》1996,77(23):4708-4711
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A. Efraty J.A. Potenza L. Zyontz J. Daily M.H.A. Huang B. Toby 《Journal of organometallic chemistry》1978,145(3):315-327
The crystal structure on dicarbonylbis(tetraphenylcyclobutadiene)molybdenum has been determined from three-dimensional X-ray data collected by counter methods. The structure consists of monomeric units with each Mo atom bonded to two carbonyl and two Ph4C4 groups. Excluding phenyl substituents, the local symmetry about Mo is very nearly C2υ. Both cyclobutadiene (CBD) groups are asymmetrically bonded to Mo, and the spread in Mo—C(CBD) distances (2.26 to 2.38 Å;) is significantly larger than that found with other structures containing substituted cyclobutadiene groups. The carbonyl groups show several short intramolecular C?C contacts with the cyclobutadiene C atoms (2.68 to 3.03 Å;) and with each other (2.63 Å;). They appear to be wedged between the Ph4C4 groups and to be responsible for the asymmetric bonding of the cyclobutadiene groups. The mass spectrum, which shows the characteristic fragmentation pattern of cyclobutadienemetal complexes, suggests a relatively high thermal stability for the title compound. Crystallographic data are as follows: space group P21/n; unit cell a 20.15(2), b 18.82(3), c 11.03(1) Å;, β 91.59(6)°; V 4181 Å;3; dcalc for Z = 4 is 1.380 and dobs is 1.365(7) g/cm3. A total of 1659 reflections with F2 ≥ 2σ were used to refine the structure to final values of RF = 0.063 and RwF = 0.041. 相似文献
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An examination of solitary waves in 3D, time‐dependant hydrostatic and Boussinesq numerical models is presented. It is shown that waves in these models will deform and that only the acceleration term in the vertical momentum equation need be included to correct the wave propagation. Modelling of solitary waves propagating near the surface of a small to medium body of water, such as a lake, are used to illustrate the results. The results are also compared with experiments performed by other authors. Then as an improvement, an alternative numerical scheme is used which includes only the vertical acceleration term. Effects of horizontal and vertical diffusion on soliton wave structure is also discussed. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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J. O. Keller J. L. Ellzey R. W. Pitz I. G. Shepherd J. W. Daily 《Experiments in fluids》1988,6(1):33-43
The reacting two-dimensional plane mixing layer has been studied in two configurations: a rearward facing step and a two-stream mixing layer. Observations have been made of the steady state behavior, and the unsteady behavior when the flow was forced by a specific acoustic frequency. The steady behavior of the mean properties of the reacting flows is similar to that of non-reacting free shear flows except for the global effects of thermodynamic property changes. The structure of these flows is qualitatively similar to that of non-reacting flows. Vortices form by the two-dimensional Kelvin-Helmholtz instability and grow by subharmonic combination until the mixing layer interacts with the walls. Entrainment is dominated by the two-dimensional vortex motion. Three-dimensional instabilities give rise to secondary vortices which are coherent over several Kelvin-Helmholtz structures and dominate the fine scale mixing process. The mixing transition corresponds to a loss of coherence in the layer. Unsteady behavior occurs when there are resonant interactions with the Kelvin-Helmholtz instability or the instability associated with the recirculation vortex in the rearward facing step flow. Modeling efforts are reported which show promise of simulating the essential features of plane mixing layers.A version of this paper was presented at the ASME Winter Annual Meeting of 1984 and printed in AMD-Vol. 66 相似文献
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Jarvis MW Daily JW Carstensen HH Dean AM Sharma S Dayton DC Robichaud DJ Nimlos MR 《The journal of physical chemistry. A》2011,115(4):428-438
The pyrolysis of 2-phenethyl phenyl ether (PPE, C(6)H(5)C(2)H(4)OC(6)H(5)) in a hyperthermal nozzle (300-1350 °C) was studied to determine the importance of concerted and homolytic unimolecular decomposition pathways. Short residence times (<100 μs) and low concentrations in this reactor allowed the direct detection of the initial reaction products from thermolysis. Reactants, radicals, and most products were detected with photoionization (10.5 eV) time-of-flight mass spectrometry (PIMS). Detection of phenoxy radical, cyclopentadienyl radical, benzyl radical, and benzene suggest the formation of product by the homolytic scission of the C(6)H(5)C(2)H(4)-OC(6)H(5) and C(6)H(5)CH(2)-CH(2)OC(6)H(5) bonds. The detection of phenol and styrene suggests decomposition by a concerted reaction mechanism. Phenyl ethyl ether (PEE, C(6)H(5)OC(2)H(5)) pyrolysis was also studied using PIMS and using cryogenic matrix-isolated infrared spectroscopy (matrix-IR). The results for PEE also indicate the presence of both homolytic bond breaking and concerted decomposition reactions. Quantum mechanical calculations using CBS-QB3 were conducted, and the results were used with transition state theory (TST) to estimate the rate constants for the different reaction pathways. The results are consistent with the experimental measurements and suggest that the concerted retro-ene and Maccoll reactions are dominant at low temperatures (below 1000 °C), whereas the contribution of the C(6)H(5)C(2)H(4)-OC(6)H(5) homolytic bond scission reaction increases at higher temperatures (above 1000 °C). 相似文献
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