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71.
A hectorite (H) clay sample has been modified with 2-mercaptobenzimidazole (MBI) using homogeneous and heterogeneous routes. Both modification methodologies resulted in similar products, named HHOM and HHET, respectively. These materials were characterized by CO2 gas adsorption, elemental analysis, nuclear magnetic nuclei of carbon-13 and silicon-29. The effect of two variables (contact time and metal concentration) has been studied using batch technique at room temperature and pH 2.0. After achieving the best conditions for Cr(VI) adsorption, isotherms of this adsorbate on using the chosen adsorbents were obtained, which were fitted to non-linear Sips isotherm model. The maximum number of moles adsorbed was determined to be 11.63, 12.85 and 14.01 mmol g−1 for H, HHOM and HHET, respectively, reflecting the maximum adsorption order of HHET > HHOM > H. The energetic effects (ΔintH°, ΔintG° and ΔintS°) caused by chromium ion adsorption were determined through calorimetric titrations. 相似文献
72.
73.
Josef-Christian Buhl Florian Stemme Irma Poltz 《Microporous and mesoporous materials》2009,126(3):276-282
The time dependent stability of tetrahydroborate sodalites with aluminosilicate- and gallosilicate framework was studied in water at room temperature and under hydrothermal conditions at 353 K. The experiments were carried out in different time intervals (4–48 h) using an excess of water according a solid:liquid mass ratio of 1:150. The kinetics of decomposition was followed by registration of weight loss, change of the pH-value and by X-ray powder diffraction as well as FT-IR spectroscopy.Both samples undergo remarkable time dependent decomposition. The decomposition rate is higher for the gallosilicate sodalite even though its crystal size is larger compare to the aluminosilicate sodalite. Besides formation of some X-ray amorphous material in both cases precipitation of crystalline aluminosilicate or gallosilicate was found, always connected with impurities of carbonate anions.FT-IR clearly showed that the remaining parts of sodalite structure of both samples were always pure tetrahydroborate sodalite. No borate species other than BH4− were detected. Thus, hydrolysis of the moisture sensitive BH4− anions by an entrance of water into intact cages can be excluded under the described experimental conditions. 相似文献
74.
Toward Next-Gen Mobile AR Games 总被引:1,自引:0,他引:1
Broll Wolfgang Lindt Irma Herbst Iris Ohlenburg Jan Braun Anne-Kathrin Wetzel Richard 《Computer Graphics and Applications, IEEE》2008,28(4):40-48
Mobile augmented reality games offer a new and rich game experience allowing players to move and interact in their physical environment with 3D content. The authors review existing approaches to mobile AR games and identify two major trends: small, user-modifiable AR games and larger-scale, event-based AR games that are interwoven with their physical environment. 相似文献
75.
76.
In this paper, the sol-gel synthesis and characteristic properties of kalsilite-type alumosilicates (KAlSiO4 and K0.5Na0.5AlSiO4) are reported. The polycrystalline powders were characterized by thermal analysis (TG/DTA), powder X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). Single-phase kalsilite oxides have been obtained after annealing precursor gels for 5 h in the temperature range of 750-850 °C. It was demonstrated that crystallinity of the samples slightly depends on the temperature of annealing. From the results obtained, it could be concluded that the KAlSiO4 solids are composed of the volumetric plate-like grains with no regular size (from 5 μm to 30 μm at 750 °C and around 5-50 μm at 850 °C). Larger crystallites for mixed potassium-sodium kalsilite have formed (from 10 μm to 80 μm at 750 °C and >100 μm at 850 °C) in comparison with potassium kalsilite samples). The erosion of obtained dental porcelain samples stored in saliva, beer and Coca-Cola was compared. 相似文献
77.
Zaln Czkus Andrs Kukri Kamirn ron Hamow Gabriella Szalai Irma Tari Attila
rdg Pter Por 《International journal of molecular sciences》2021,22(15)
The first line of plant defence responses against pathogens can be induced by the bacterial flg22 and can be dependent on various external and internal factors. Here, we firstly studied the effects of daytime and ethylene (ET) using Never ripe (Nr) mutants in the local and systemic defence responses of intact tomato plants after flg22 treatments. Flg22 was applied in the afternoon and at night and rapid reactions were detected. The production of hydrogen peroxide and nitric oxide was induced by flg22 locally, while superoxide was induced systemically, in wild type plants in the light period, but all remained lower at night and in Nr leaves. Flg22 elevated, locally, the ET, jasmonic acid (JA) and salicylic acid (SA) levels in the light period; these levels did not change significantly at night. Expression of Pathogenesis-related 1 (PR1), Ethylene response factor 1 (ERF1) and Defensin (DEF) showed also daytime- and ET-dependent changes. Enhanced ERF1 and DEF expression and stomatal closure were also observable in systemic leaves of wild type plants in the light. These data demonstrate that early biotic signalling in flg22-treated leaves and distal ones is an ET-dependent process and it is also determined by the time of day and inhibited in the early night phase. 相似文献
78.
Cestari AR Vieira EF Vieira GS da Costa LP Tavares AM Loh W Airoldi C 《Journal of hazardous materials》2009,161(1):307-316
The three-parameter Sips adsorption model was successfully employed to modeled equilibrium adsorption data of a yellow and a red dye onto a mesoporous aminopropyl-silica, in the presence of the surfactant sodium dodecylbenzenesulfonate (DBS) from 25 to 55 degrees C. The results were evaluated in relation to the previously reported surface tension measurements. The presence of curvatures of the van()t Hoff plots suggested the presence of non-zero heat capacities terms (Delta(ads)C(p)). For the yellow dye, it is observed that the values of Delta(ads)H are almost all positive and they decrease in endothermicity, in the absence and in the presence of DBS, from 25 to 55 degrees C. For the red dye, there is an increase in endothermicity in relation to the temperature increase. The negative Delta(ads)G values indicate spontaneous adsorption processes. Almost all adsorption entropy values (Delta(ads)S) were positive. This suggests that entropy is a driving force of adsorption. The adsorption thermodynamic parameters were also evaluated using a new 2(3) full factorial design analysis. The multivariate polynomial modelings indicated that the thermodynamic parameters are also affected by important interactive effects of the experimental factors and not by the temperature changes alone. 相似文献
79.
The synthetic Kenyaite sample was used for organofunctionalization process with N-propyldiethylenetrimethoxysilane and bis[3-(triethoxysilyl)propyl]tetrasulfide. The resulted materials were submitted to process of adsorption with arsenic solution at pH 2.0 and 298+/-1K. The adsorption isotherms were adjusted using a modified Langmuir equation with regression non-linear; the net thermal effects obtained from calorimetric titration measurements were adjusted to a modified Langmuir equation. The adsorption process was exothermic (Delta(int)H=-4.08 to -5.94 kJ mol(-1)) accompanied by increase in entropy (Delta(int)S=41.29-62.09 J K(-1)mol(-1)) and Gibbs energy (Delta(int)G=-22.33 to -24.45 kJ mol(-1)). The energetic effect caused by metal cation adsorption was determined through calorimetric titration at the solid-liquid interface and gave a net thermal effect that enabled the calculation of the exothermic values and the equilibrium constant. 相似文献
80.
The objective of this research was to prepare pregelatinized maize starches that were both completely amorphous (no crystalline structure) and unfragmented, and to apply the same method to partially depolymerized maize starches to determine the effect of fragmentation on the degree of stickiness (tackiness, adhesiveness). Amorphous pregelatinized normal maize starch could be prepared by precipitation of a paste with acetone. Precipitation with a polar organic solvent was not applicable for the preparation of amorphous, pregelatinized waxy maize starch, because a sticky, cohesive and adhesive mass was produced. Therefore, freeze drying was used to prepare amorphous pregelatinized waxy maize starch. Limited acid‐catalyzed hydrolysis of normal maize starch before pregelatinization increased stickiness up to a maximum, after which the degree of stickiness decreased. In all aspects of this research, it was clear that the behavior of waxy maize starch was rather different than that of normal maize starch. 相似文献