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81.
阳离子膨润土对分散染料的吸附动力学研究 总被引:13,自引:1,他引:13
研究了阳离子膨润土(EPI-DMA/Bt, PD/Bt, CTMAB/Bt)对分散染料(分散黄棕S-2RFL, 分散大红S-R, 分散蓝SBL, 分散黄SE-6GFL)的吸附动力学行为. 结果表明, 阳离子膨润土对分散染料的吸附过程符合二阶段吸附速率方程, 各阶段具有不同的吸附动力学常数(k1, k2)以及吸附活化能(Ea1, Ea2)、活化焓(ΔH*1, ΔH*2)和活化熵(ΔS*1, ΔS*2); 在阳离子膨润土对分散染料的吸附过程中, k1随着阳离子插层剂烷烃链的增加而增大, 表明较大的晶片层间距, 疏水的层间域和表面正电荷增加均有利于吸附速率增大; 对于两个吸附动力学阶段, ΔH★1<-TavΔS★1, △H★2<-TavΔS★2和ΔG★>0表明整个吸附过程活化熵的影响大于活化焓. 相似文献
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Amphoteric superabsorbent composite with semi-interpenetrating polymer networks (semi-IPN) composed of poly(acrylic acid) (PAA)/Ca-bentonite/poly(dimethyldiallylammonium chloride) (PDMDAAC) was prepared by a combination of intercalative polymerization and a sequential IPN method and the effects of reaction parameters on the swelling capacity were studied. PDMDAAC was used as a polycation to modify bentonite and form semi-IPN with lightly crosslinked PAA. FTIR and TG were used to characterize the amphoteric superabsorbent composites with semi-IPN. The thermal stability of the product was not degraded as in the case of using small molecular surfactant to modify bentonite. The contents of carboxylic groups and nitrogen had been determined. This indicated that the product with certain content of carboxylic groups and nitrogen is inclined to exhibit excellent swelling capacity. The presence of PDMDAAC improved the swelling capacity. The resulting amphoteric superabsorbent composite showed excellent swelling capacity of 1578 g/g in distilled water and 136 g/g in 0.9 wt% NaCl solution. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
83.
J. Eric D. Davies Nusrat Jabeen 《Journal of inclusion phenomena and macrocyclic chemistry》2002,43(3-4):329-336
The adsorption of isoproturon and two model compounds, N,N-dimethylurea and4-isopropylaniline, on clay minerals (bentonite,montmorillonite and kaolinite), organic matter (humic acid) and soil (with and without organic matter) has been studied using FT-infrared spectroscopy (IR), thermogravimetric analysis (TGA), high pressure liquid chromatography (HPLC) and X-ray diffraction (XRD).N,N-dimethylurea interacted with bentonite and montmorillonite by the coordination of the carbonyl group, directly or indirectly through water molecules, with exchangeable cations. Adsorption on humic acid was due to hydrogen bonding with the active sites of the adsorbent. The amino group ofN,N-dimethylurea appears tobe relatively inactive during adsorption. The mechanisms involved in the adsorption of 4-isopropylaniline were hydrogen bonding and protonation. No adsorption of 4-isopropylaniline was observed on kaolinite. The investigation of isoproturon suggested that both the carbonyl and amino groups of isoproturon were involved in interactions with the active sites of the adsorbents. Both the clay minerals and organic matter of soil contribute to the adsorption of organic compounds on soil but the clay minerals bentonite and montmorillonite play a major role in their adsorption on soil. 相似文献
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Clay-hydrogel nanocomposites are suitable material for mitigating the pollution/environmental impact because of their high adsorption capacity. In this study, the synthesis of polyacrylamide/bentonite hydrogel nanocomposite was assisted by ultrasound through successful incorporation of nanobentonite as filler and cross-linker into polyacrylamide framework. The adsorbent was characterized by FTIR, XRD, BET, SEM-EDX, and TEM in order to observe structural changes and sorption interactions. The effect of adsorbent dose, contact time, initial metal ion concentration and pH on the sequestration of Pb2+ and Cd2+ was analyzed. The adsorbent removed more than 95% Pb2+ and Cd2+ within first 20 min, which corresponds to relatively high pseudo-first order rate constant, k1 (0.240 for Pb2+ and 0.253 1/min for Cd2+) and pseudo-second order rate constant, k2 (0.031 for Pb2+ and 0.033 g/mg/min for Cd2+). The isotherm and kinetics modeling data were best described by Freundlich isotherm over the entire concentration range and pseudo-second order rate equation, respectively. The thermodynamic studies implied spontaneous and endothermic nature of adsorption process. The maximum adsorption capacity (138.33 for Pb2+ and 200.41 mg/g for Cd2+) determined using Langmuir model along with a good regeneration potential depicts that polyacrylamide/bentonite hydrogel nanocomposite could be used effectively for Pb2+ and Cd2+ uptake from aqueous solution. 相似文献
88.
Efficient photoinduced In situ preparation of clay/poly(glycidyl methacrylate) nanocomposites using hydrogen‐donor silane 下载免费PDF全文
Khouloud Jlassi Mémia Benna‐Zayani Mohamed M. Chehimi Yusuf Yagci 《Journal of polymer science. Part A, Polymer chemistry》2015,53(6):800-808
Clay/poly(glycidyl methacrylate) nanocomposites (clay/PGMA) were prepared by in situ radical photopolymerization using N,N‐dimethylaminopropyltrimethoxysilane(DMA)‐modified bentonite clay acting as hydrogen donor for benzophenone in solution. This initiating system permits to photopolymerize glycidyl methacrylate between the lamellae of the DMA‐modified clay. The approach provides exfoliated nanocomposites as judged by the measurements of X‐ray diffraction. However, a low fraction of persistent intercalated clay regions was visible by transmission electron microscopy. X‐ray photoelectron spectra analyses indicate that the nanocomposites have PGMA‐rich surface. The clay/PGMA nanocomposites can be readily dispersed in ethanol. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 800–808 相似文献
89.
Nesrine Dammak Olfa Ouledltaief Nadim Fakhfakh Mourad Benzina 《Surface and interface analysis : SIA》2014,46(7):457-464
Tunisian bentonites were used to prepare three modified clays: two organoclays by intercalating respectively didodecyldimethylammoniumbromide (DDMAC) and hexadecyltrimethylammoniumbromide (HDTMAC), and synthesis of NaX zeolite. The X‐ray diffraction, infrared and thermogravimetric analyses enabled us to differentiate between the structures obtained. Clay materials systems were used as adsorbent for the investigation of the adsorption isotherms and saturation capacity of O‐xylene, a toxic volatile organic compound, by gravimetric method at three different temperatures 20, 30, and 40 °C. The absolute values of the volatile organic compound adsorbed amounts in the intercalated clays (604 mg g?1) were higher than for the zeolite (296 mg g?1). The adsorption isotherms were analysed by the Freundlich and Langmuir equations. The latter was found to describe better the equilibrium adsorption data. Mass transfer coefficient of O‐xylene is evaluated using uptake curve method, and all values are in the order of 10?2 s?1. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
90.
Devendrapratap U. Singh 《Tetrahedron letters》2004,45(49):9079-9082
Fe-pillared bentonite (Fe-PILC) was shown to be an extremely efficient catalyst for the sulfonylation of activated as well as unactivated carbocyclic aromatic compounds and heterocyclic aromatic compounds. The catalyst was also found to be recyclable. 相似文献