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111.
Jih-Hsing Chang Zhimin Qiang Chin-Pao Huang Amanda V. Ellis 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,348(1-3):157-163
In this study, the remediation performance of electrokinetic (EK) technology integrated with different surfactants for removing phenanthrene from unsaturated soils was investigated. A synthetic surfactant (Triton X-100) and a biosurfactant (rhamnolipid) were used to enhance phenanthrene solubility and removal efficiency during EK process. Results indicate that the electro-osmotic flow (EOF) rate in the rhamnolipid system is higher than that in Triton X-100. Using the EK technology for the removal of phenanthrene in the presence of rhamnolipid was more efficient than in the presence of Triton X-100. In addition to the transport mechanism of phenanthrene in EK system, the presence of rhamnolipid may promote microbial growth in the soil–water system and bring about biodegradation of phenanthrene. A diffusion–advection–sorption (DAS) model was solved by MATLAB, based on the linear sorption isotherm at the non-equilibrium condition, which is feasible to simulate the movement of phenanthrene during the EK + Triton X-100 treatment. 相似文献
112.
In this work, the synthetic utility of the Ferrier reaction to access S-linked disaccharides and S-linked glycoamino acids has been probed. Significantly, entry to a range of 1,4- and 1,6-S-linked disaccharides has been achieved using glycals derived from glucose and galactose, and sulfur containing coupling partners derived from methyl α-d-glucopyranoside. Access to S-linked glycoamino acids and glycopeptides has also been achieved using protected cysteine and homocysteine coupling partners within the Ferrier reaction. Functionalisation of the Ferrier products, for example, via dihydroxylation using OsO4 or amino acid coupling, and deprotection of the targets have also been achieved. In this way, entry to materials of interest as mimics of biologically interesting disaccharides and glycopeptides has been realised, including targets derived from rare sugars such as talopyranose and gulopyranose. 相似文献
113.
Jonathan A. Batten Craig A. Ellis Thomas A. Fethertson 《Chaos, solitons, and fractals》2008,36(5):1126-1140
This study employs the classical and modified rescaled adjusted range statistic (R/S statistic) to investigate the sensitivity of the long-term return anomaly observed on the Dow Jones Industrial Average (DJIA) to sample and method bias. Daily data from 1/1/1970 to 17/3/2004 is used with sub-periods identified based on sign shifts in the mean returns as well as the October 1987 crash. The return series are also filtered to accommodate autoregressive conditional heteroskedastic (ARCH) innovations and short-term dependencies. Hurst exponent and V-statistic values for each of the filtered series for the whole sample and sub-periods are estimated, while polynomial regression techniques are applied to plot the V-statistics. These plots show oscillating cycles of varying lengths. Overall, we find the null hypothesis of no long-term dependence is accepted for the whole sample and every sub-period using the modified rescaled range test, but not necessarily using the classical rescaled adjusted range test. The later test does, however, reveal episodes of both positive and negative dependence over the various sample periods, which have been reported by other researchers. 相似文献
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115.
John Ellis 《Discrete Applied Mathematics》2008,156(5):545-555
We present proofs of lower bounds on the node search number of some grid-like graphs including two-dimensional grids, cylinders, tori and a variation we call “orb-webs”. Node search number is equivalent to pathwidth and vertex separation, which are all important graph parameters. Since matching upper bounds are not difficult to obtain, this implies that the pathwidth of these graphs is easily computed, because the bounds are simple functions of the graph dimensions. We also show matching upper and lower bounds on the node search number of equidimensional tori which are one less than the obvious upper bound. 相似文献
116.
Kshitish Patankar David A. Dillard Scott W. Case Michael W. Ellis Yongqiang Li Yeh‐Hung Lai Michael K. Budinski Craig S. Gittleman 《Journal of Polymer Science.Polymer Physics》2010,48(3):333-343
Pinhole formation in proton exchange membranes (PEM) may be caused by a process of flaw formation and crack propagation within membranes exposed to cyclic hygrothermal loading. Fracture mechanics can be used to characterize the propagation process, which is thought to occur in a slow, time‐dependent manner under cyclic loading conditions, and believed to be associated with limited plasticity. The intrinsic fracture energy has been used to characterize the fracture resistance of polymeric material with limited viscoelastic and plastic dissipation, and has been found to be associated with long‐term durability of polymeric materials. Insight into this limiting value of fracture energy may be useful in characterizing the durability of proton exchange membranes, including the formation of pinhole defects. In an effort to collect fracture data with limited plasticity, a knife slit test was adapted to measure fracture energies of PEMs, resulting in fracture energies that were two orders of magnitude smaller than those obtained with other fracture test methods. The presence of a sharp knife blade reduces crack tip plasticity, providing fracture energies that may be more representative of the intrinsic fracture energies of the thin membranes. Three commercial PEMs were tested to evaluate their fracture energies (Gc) at temperatures ranging from 40 to 90 °C and humidity levels varying from dry to 90% relative humidity (RH). Experiments were also conducted with membrane specimens immersed in water at various temperatures. The time temperature moisture superposition principle was applied to generate fracture energy master curves plotted as a function of reduced cutting rate based on the humidity and temperature conditions of the tests. The shift with respect to temperature and humidity suggests that the slitting process is viscoelastic in nature. Also such shifts were found to be consistent with those obtained from constitutive tests such as stress relaxation. The fracture energy is more sensitive to temperature than on humidity. The master curves converge at the lowest reduced cutting rates, suggesting similar intrinsic fracture energies; but diverge at higher reduced cutting rates to significantly different fracture energies. Although the relationship between Gc and ultimate mechanical durability has not been established, the test method may hold promise for investigating and comparing membrane resistance to failure in fuel cell environments. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 333–343, 2010 相似文献
117.
George Ellis 《Foundations of Physics》2018,48(10):1226-1245
The present day standard cosmological model is a great theoretical achievement. This chapter surveys the main themes that have arisen and issues that are still oustanding. 相似文献
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119.
George F. R. Ellis Roy Maartens Malcolm A. H. MacCallum 《General Relativity and Gravitation》2007,39(10):1651-1660
A usual causal requirement on a viable theory of matter is that the speed of sound be at most the speed of light. In view
of various recent papers querying this limit, the question is revisited here. We point to various issues confronting theories
that violate the usual constraint. 相似文献
120.