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81.
82.
Malek Bendjaballah Rabah Oumeddour 《Journal of Dispersion Science and Technology》2013,34(9):1260-1272
To find an optimal formulation of oil-in-water (O/W) emulsions (φo = 0.05), the effect of emulsifier nature and concentration, agitation speed, emulsifying time, storage temperature and their mutual interactions on the properties and behavior of these dispersions is evaluated by means of an experimental design (Nemrodw software). Long-term emulsion stability is monitored by multiple light scattering (Turbiscan ags) and acoustic attenuation spectroscopy (Ultrasizer). After matching surfactant HLB and oil required HLB, a model giving the Sauter diameter as a function of emulsifier concentration, agitation speed and emulsification time is proposed. The highest stability of C12E4-stabilized O/W emulsions is observed with 1% emulsifier. 相似文献
83.
Wumanjiang Eli Wenhai Chen Qunji Xue 《Journal of Dispersion Science and Technology》2013,34(6):1659-1674
A series of triblock nonionic surfactants with different Propylene oxide and ethylene oxide chain lengths were synthesized. The triblock nonionic surfactants and poly(ethylene glycols) with different molecular weight were used, to find the effects of polymer chain length and size of the micelles on the cloud point of the surfactants. Two possible models are considered on the basis of cloud point changes of the solutions, to describe the polymer- surfactant interactions. One model suggests that flocculation depletion for the polymer chains exist between two regular micelles. This provides the driving force for the neighboring micelles to approach each other and destabilize the colloidal system. The flocculation effect is more important for polymers with a shorter chain block the approach of the micelles, since there is no typical polymer-surfactant association formed but just simple small molecule associations in which the steric and solvation effects of the polymer chains make the inter-micelles interactions repulsive. The other model considers that intra-chain micelles of polysoap are formed among the surfactant monomers and long polymer chains. The bridging attraction between two intra-chain micelles in such structures can enhance the collisions among the micelles, due to the exchange of amphiphilic monomers among the neighboring micelles. 相似文献
84.
Tingting Zhou Xiaohui Xu Xiangying Wang Guojun Dong 《Journal of Dispersion Science and Technology》2013,34(9):1189-1194
Nonionic gemini surfactants HBA(EO)80 were synthesized and characterized by means of surface tension measurements. CMCs of two mixed system, nonionic gemini mixed with anionic gemini (HBA(EO)80/C11pPHCNa) and nonionic gemini mixed with anionic monomeric (HBA(EO)80/SL) and the effect of salt on the two mixed system were investigated. Freeze-fracture transmission electron microscopy and scanning electron microscopy were used to investigate the mixed aggregates' morphologies. The results show that large spherical aggregates were formed in the mixed solution, which trend to transfer into micelles with the increases of the salt concentration. 相似文献
85.
Ayman M. Atta Adel A.-H. Abdel-Rahman Nora A. Hamad 《Journal of Dispersion Science and Technology》2013,34(9):1222-1232
Water soluble nonionic surfactants based on Schiff base monomers were prepared by their etherification with β,` β- dichlorodiethylether and PEG 400 in presence of NaOH. The surface properties of the prepared surfactants were determined by measuring the surface tension at different temperatures. The prepared nonionic surfactants were evaluated as demulsifiers for synthetic water in crude-oil emulsions that were pronounced at different ratios of crude oil: water at 45°C and 60°C. The experimental results showed that the dehydration rate of the prepared demulsifiers reached 90% and 100% at some concentrations. 相似文献
86.
Pseudo-first-order rate constants, kobs, for the alkaline hydrolysis of N-hydroxyphthalimide, 1, at 0.02 M NaOH and 30°C remain essentially independent of the total concentration of C12E23, [C12E23]T, at ≤0.005 M C12E23. The increase in [C12 E23]T from 0.005 to 0.015 M causes a nonlinear decrease in kobs. The rate of hydrolysis becomes either too slow or the change in absorbance values becomes significantly small to allow a reliable observed data fit to a first-order kinetic equation at ≥0.020 M C12E23 in the absence and presence of total concentration of cetyltrimethylammonium bromide, [CTABr]T ranging from 0.003 to 0.020 M. The values of fraction of nonionized 1, FSH, obtained at reaction time t = 0 and 0.02 M NaOH, remain ~0 at ≤0.010 M C12E23 while they increase from 0.39 to 0.89 with the increase of [C12E23]T from 0.015 to 0.10 M. The values of kobs show a nonlinear decrease of ~5-fold with the increase of [C12E23]T from 0.0 to 0.010 M in the presence of 0.02 M NaOH and [CTABr]T range of 0.003 to 0.020 M. The values of FSH remain ≤~0.10 at ≤0.015 M C12E23 while they vary between 0.40 and 0.90 within a [C12E23]T range 0.02 to 0.05 M in the presence of 0.02 M NaOH and [CTABr]T ranging from 0.003 to 0.020 M. The values of FSH represent the fraction of nonionized 1 trapped almost irreversibly by pure C12E23, and mixed C12E23–CTABr micelles. 相似文献
87.
Abstract Ethoxylated alcohols are the most extensively used nonionic surfactants in detergent products. The application of QSAR to their aquatic toxicity is complicated by the fact that they are multicomponent mixtures, the parent alcohols being often mixtures of isomers and homologues, each one being ethoxylated to varying degrees. A spreadsheet method for calculation of aquatic toxicity of such nonionic surfactant mixtures is presented. The method is based on a combination of the Könemann narcosis QSAR and mixture toxicity equations based on the principle of concentration addition. Log P values used in the spreadsheet calculations are themselves calculated by spreadsheet formulae based on the Leo and Hansch method modified by incorporation of the position dependent branching factor originally applied to linear alkylbenzene sulphonates. Close agreement between calculated and experimental EC50 values (48 hr Daphnia tests) is obtained for a range of ethoxylated alcohols having a diversity of branching patterns, carbon numbers and degrees of ethoxylation. The effects of increasing carbon number (decreasing EC50), branching (increasing EC50) and increasing degree of ethoxylation (increasing EC50) are all quantified. 相似文献
88.
The surface roughness seriously affects the performance of devices after barrier CMP. Due to the high surface roughness of copper line, the local resistance of a device will be high when working, then the copper line will overheat prompting the generation of electro-migration and the circuit will lose efficacy. Reducing the surface roughness of the copper line in barrier CMP is still an important research topic. The main factors influencing the surface roughness of copper line in alkaline barrier slurry are analyzed in the paper. Aimed at influencing the law on the surface roughness of copper line, using a new type of alkaline barrier slurry with a different p H of the chelating agent and changing the content of non-ionic surfactant, we then analyze the influencing law both on the surface roughness of copper line, and the influence mechanism. The experimental results show that with a chelating agent with a low p H value in the barrier slurry, the surface roughness of the copper line is 1.03 nm and it is the lowest in all of the barrier slurries, and with the increase of non-ionic surfactant concentration, the surface roughness of copper line is reduced to 0.43 nm, meeting the demand of further development of integrated circuits. 相似文献
89.
Takao Shibusawa 《Journal of Polymer Science.Polymer Physics》1993,31(1):29-35
Diffusion of 2,4-dinitroaniline and three nonionic azo dyes in Nylon-6 film was studied by analysis of the concentration-distance curves (profiles) of penetrants in the polymer. Actual diffusivities D(c) of penetrants in polymer, diffusion coefficients as a function of the concentration Cf of penetrant in polymer, were calculated from the profile. It was found that D(c) is almost constant or decreases gradually with decreasing Cf in the range of high-medium Cf but decreases appreciably with decreasing Cf at low Cf. The change in D(c) with Cf was explained in terms of the dual-mode sorption-diffusion model. The penetrants diffuse in the polymer as two distinct species, i.e., a dissolved species and an adsorbed species. The former is the penetrant taken up by the polymer by a partition mechanism (dissolved species) and the latter is that taken up by Langmuir sorption (adsorbed species). The actual diffusivity DP(c) of the dissolved species decreases with decreasing Cf. While the actual diffusivity DL(c) of the adsorbed species normally increases gradually with decreasing Cf. DP(c) is usually larger than DL(c). © 1993 John Wiley & Sons, Inc. 相似文献
90.
Viscosities and densities of sucrose in aqueous alkali metal halide solutions of different concentrations in the temperature
range 293.5 to 313.15 K have been measured. Partial molar volumes at infinite dilution (V
2
0
) of sucrose determined from apparent molar volume (φ
v
) have been utilized to estimate partial molar volumes of transfer (V
2,tr
0
) for sucrose from water to alkali metal halide solutions. The viscosity data of alkali metal halides in purely aqueous solutions
and in the presence of sucrose at different temperatures (293.15, 303.15 and 313.5 K) have been analysed by the Jones-Dole
equation. The nature and magnitude of solute-solvent and solute-solute interactions have been discussed in terms of the values
of limiting apparent molar volume (φ
v
0
), slope (S
v
) and coefficients of the Jones-Dole equation. The structure-making and structure-breaking capacities of alkali metal halides
in pure aqueous solutions and in the presence of sucrose have been ascertained from temperature dependence ofφ
v
0
. 相似文献