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83.
In this work, a simple equation of state (EoS) has been used to predict some thermodynamic properties of air as a pseudo-pure
fluid; as a ternary mixture of nitrogen, oxygen, and argon; and as a binary mixture of nitrogen and oxygen at different temperatures
and pressures. A comparison with literature tabulated values has been made. The agreement of calculated densities with corresponding
tabulated values is good for which the average absolute deviations are better than 0.06% if we assume air as a pseudo-pure
fluid, and 0.9% and 1.2% if we consider air as a ternary mixture and as a binary mixture, respectively. To show the ability
of this equation of state to predict density, the calculated densities of air have been compared with those computed by other
methods. 相似文献
84.
《Science & Technology of Welding & Joining》2013,18(6):496-508
AbstractThe objective of this paper is to demonstrate a new simulation technique which allows fast and automatic generation of temperature fields as input for subsequent thermomechanical welding simulation. The basic idea is to decompose the process model into an empirical part based on neural networks and a phenomenological part that describes the physical phenomena. The strength of this composite modelling approach is the automatic calibration of mathematical models against experimental data without the need for manual interference by an experienced user. As an example for typical applications in laser beam and GMA–laser hybrid welding, it is shown that even 3D heat conduction models of a low complexity can approximate measured temperature fields with a sufficient accuracy. In general, any derivation of model fitting parameters from the real process adds uncertainties to the simulation independent of the complexity of the underlying phenomenological model. The modelling technique presented hybridises empirical and phenomenological models. It reduces the model uncertainties by exploiting additional information which keeps normally hidden in the data measured when the model calibration is performed against few experimental data sets. In contrast, here the optimal model parameter set corresponding to a given process parameter is computed by means of an empirical submodel based on relatively large set of experimental data. The approach allows making a contribution to an efficient compensation of modelling inaccuracies and lack of knowledge about thermophysical material properties or boundary conditions. Two illustrating examples are provided. 相似文献
85.
苯乙烯-GMA共聚物的合成及其在尼龙6/聚苯醚共混体系中的应用 总被引:1,自引:0,他引:1
采用悬浮聚合方法合成了苯乙烯-甲基丙烯酸缩水甘油酯(GMA)共聚物(SG),讨论了各种实验条件对聚合反应的影响。SG共聚物能够有效地与尼龙6分子链端的胺基、羧基和聚苯醚分子链端的羧基发生反应,生成接枝共聚物。将其用于尼龙6/聚苯醚共混体系,发现尼龙6(PA6)/聚苯醚(PPO)/SG三元合金体系与组成相同的PA6/PPO二元合金体系相比,材料的拉伸强度和断裂伸长均得到提高。这种共聚物可以作为适用于尼龙/聚苯醚合金体系的反应型增容剂。 相似文献
86.
Benzoyl peroxide is widely applied as an initiator–accelerator system in combination with tertiary amines for the polymerization of water-miscible methacrylates. However, this system is very sensitive to the ambient temperature and the evolution of exothermic heat is, especially at room temperature (293 K), difficult to control. Temperatures involved may increase beyond 373 K. A linear correlation between a graded series of benzoyl peroxide (0.2–1.0 g% benzoyl peroxide/glycol methacrylate) and the maximum temperature within the polymerizing plastic was established using a commercially-available embedding system. Commercially-available glycol methacrylates contain various concentrations of inhibitor in order to prevent spontaneous polymerization of the monomer. We tested a series of 200–300–400–800 ppm of the inhibitor hydroquinone and found a significant influence exerted upon the maximum temperature and the moment at which the maximum temperature was reached. Supplementary addition of inhibitors to the GMA monomer may effect a decrease of the maximum temperature within polymerizing GMA mixtures. Possibilities for standardizing the polymerization of glycol methacrylate by means of the benzoyl peroxide/tertiary amine initiator–accelerator system at room temperature are discussed. 相似文献
87.
88.
The kinetics of radical polymerization of glycidyl methacrylate, initiated by the free radicals formed in situ in the multi‐site phase transfer catalyst (PTC), 1,1,2,2‐tetramethyl‐1‐benzyl‐2‐n‐propylethylene‐1,2‐diammonium bromide chloride–potassium peroxydisulfate system was studied in an aqueous–organic two‐phase media at 60°C ± 1°C under inert and unstirred condition. The rate of polymerization (Rp) was determined at various concentrations of the monomer, initiator, catalyst, and volume fraction of aqueous phase. The effect of acid, ionic strength, and water‐immiscible organic solvents on the Rp was examined. The temperature dependence of the rate was studied, and activation parameters were calculated. Rp increased with an increase in the concentrations of monomer, initiator, multi‐site PTC, and increase in the polarity of solvent and temperature. The order with respect to monomer, initiator, and multi‐site PTC was found to be 0.50. A feasible free‐radical mechanism consistent with the experimental data has been proposed, and its significance was discussed. The synthesized polymer was confirmed by Fourier transform infrared spectral analysis. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
89.
采用熔融接枝法制备聚烯烃热塑弹性体(POE)接枝甲基丙烯酸缩水甘油酯(GMA),将接枝物[POE-g-(GMA-g-St))]用于聚对苯二甲酸丁二醇酯(PBT)的增韧改性。研究了接枝物含量对共混物力学性能、结构以及熔融结晶行为的影响。结果表明:POE-g-(GMA-g-St)对PBT具有良好的增韧效果,当加入弹性体30%时,共混物的冲击强度为71.97 kJ/m2。SEM图像显示:作为分散相的接枝物在PBT基体中的尺寸更小且粒径分布更均匀。DSC图像显示出现两个熔融峰且随接枝物含量的增加其结晶度逐渐降低。 相似文献
90.
M. Talha GokmenFilip E. Du Prez 《Progress in Polymer Science》2012,37(3):365-405
This review is written to fulfill the need of a comprehensive guide for the manufacture of porous polymer particles. The synthesis section discusses and for the first time compares microfluidics, membrane/microchannel, suspension, dispersion, precipitation, multistage polymerizations and a few other less known methods, microfluidics being in greater detail. The comparison includes on one hand simplicity, scaling-up possibilities and the ability to yield nonspherical particles for these methods and on the other hand size, size monodispersity, pore characteristics and chemical functionality of the obtained particles. This extensive comparison certainly makes this review also useful for the preparation of nonporous particles. In addition, functionalization/characterization techniques and applications of porous particles are also discussed, including some visionary recommendations. The review is expected not only to enable individual experts of each field to compare their methods with the other ones, but also to be a handbook for the newcomers to this field to guide them from the synthesis to the applications. 相似文献