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41.
利用稀土配合物具有较强协同作用的优点,将自身对聚氯乙烯(PVC)具有一定热稳定作用的乙二胺双马来酰胺酸根合镧(Ⅲ)配合物(LaL)与层状矿物,如高岭土、蒙脱土、水滑石和水镁石进行复配,通过热重分析、刚果红试验和静态烘箱老化法研究了乙二胺双马来酰胺酸根合镧(Ⅲ)与高岭土、蒙脱土、水滑石和水镁石复合物对PVC热稳定性的影响。结果表明,乙二胺双马来酰胺酸根合镧(Ⅲ)与层状矿物具有良好的协同效应,且与水镁石效果最为显著,当二者质量比为1∶1时,PVC热稳定时间由2 min提升至70 min,且能有效地抑制单一稀土热稳定剂使用时的初期着色能力。复合热稳定剂的添加大幅度提高了PVC热降解的活化能,尤其是LaL-水镁石复合物(LaL-Brucite)的添加,N_2气氛下的活化能相对于纯PVC样品,由123.5 kJ/mol提升至234.7 kJ/mol,提高了111.2 kJ/mol;空气气氛下的活化能相对于纯PVC样品,由115.9 kJ/mol提升至133.0 kJ/mol,提高了17.1 kJ/mol;有效地提高了PVC的热稳定性。 相似文献
42.
N-十四烷基甘氨酸柱撑水滑石的制备、表征及在环氧胶粘剂中的应用 总被引:3,自引:1,他引:3
采用共沉淀法成功制备了N 十四烷基甘氨酸柱撑水滑石(简称N LDH)Mg4Al2(OH)12[C14H29NHCH2COO],并用XRD、FTIR对样品进行表征。结果表明,C14H29NHCH2COO-可进入水滑石层间,N LDH具有良好的层状结构,其层间距由0 759nm增加到2 418nm;实验结果表明,在E44/T31环氧胶粘剂体系中加入N LDH可有效改善其力学性质,当w(N LDH)=5%时,拉伸剪切强度提高了53 7%。 相似文献
43.
Wen‐Zhuo Li Jun Lu Jie‐Sheng Chen Guo‐Dong Li Yu‐Sheng Jiang Lian‐Sheng Li Bai‐Qu Huang 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(1):89-93
Phenoxymethylpenicillin (PMP) has been reversibly intercalated into a layered double hydroxide, and the resulting composite exhibits effective anti‐bacterial activity. Powder X‐ray diffraction studies indicate that the PMP molecules are interdigitated between the inorganic layers, and under mild acidic media, the molecules are released gradually. Therefore a sustained‐release anti‐bacterial medication is envisioned on the basis of this inorganic–drug composite. Copyright © 2005 Society of Chemical Industry 相似文献
44.
Supported Pd catalysts were prepared by solid-phase crystallization (spc) starting from MgAl hydrotalcite anionic clay minerals as the precursors, and were tested for the methanol decomposition to synthesis gas. The precursors based on [Mg6Al2(OH)16CO3
2-] · 4H2O were prepared by coprecipitation from raw materials containing Pd2+, Mg2+ and Al3+ ions as the components of hydrotalcite. The precursors were thermally decomposed and reduced to afford supported Pd catalysts on MgAl mixed oxide. Pd-supported catalysts as a reference were also prepared by the impregnation (imp) method. The spc-Pd catalysts thus prepared afforded highly dispersed Pd metal particles and showed higher activity as well as lower activation energy than the imp-Pd catalysts. When the precursor was prepared under mild conditions, finer particles of Pd metal were formed over the catalyst, resulting in a high activity. In the case of spc-Pd catalysts, carbon monoxide adsorbed on Pd easily desorbed, compared with imp-Pd catalysts. It is likely that the high activity is due to the highly dispersed and stable Pd metal particles and the easy desorption of carbon monoxide. 相似文献
45.
Selective hydrogenation of cinnamaldehyde using Pd catalysts supported on Mg/Al mixed oxides: Influence of the Pd incorporation method
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María J. Martínez‐Ortiz Miguel A. de la Rosa‐Guzmán Jorge R. Vargas‐García Jorge L. Flores‐Moreno Nancy Castillo Ariel Guzmán‐Vargas Sara Morandi Rosa M. Pérez‐Gutiérrez 《加拿大化工杂志》2018,96(1):297-306
A series of hydrotalcite‐like compounds was synthesized by varying Mg/Al molar ratio with values of 2, 3, and 4. After thermal treatment at 823 K, the corresponding mixed oxides were obtained and used as catalytic supports. The incorporation of a Pd metallic phase (0.5 g/g loading), was carried out by two methods: 1) in situ vapour phase thermal decomposition, and 2) impregnation by organic method. Fresh and calcined samples were characterized by XRD and N2 sorption experiments. The basic and metal functions were analyzed by CO2‐TPD and H2‐TPR. The Pd‐support interaction was studied by FTIR spectroscopy using CO as a probe molecule while the morphology of Pd nanoparticles on the catalysts was studied by SEM, HRTEM, and theoretical simulation using the Fast Fourier Transform (FFT) method. Finally, the catalytic activity results showed a higher conversion towards hydrocinnamaldehyde in the cinnamaldehyde hydrogenation reaction for the catalysts prepared by vapour phase thermal decomposition, compared with those prepared by organic method, showing the significant dependence on the catalytic activity and the Pd incorporation method. 相似文献
46.
Structure and analgesic properties of layered double hydroxides intercalated with low amounts of ibuprofen
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Robson Sousa Jenny Jouin Olivier Masson Fabien Remondiere Alex Lemarchand Maggy Colas Philippe Thomas Jerônimo Lameira Gilmara N. T. Bastos Anderson B. Lima José L. M. Nascimento Marcos Anicete‐Santos Waldinei R. Monteiro Cláudio N. Alves 《Journal of the American Ceramic Society》2017,100(6):2712-2721
Ibuprofen‐intercalated layered double hydroxides (LDH‐IBU) have been successfully synthesized via a coprecipitation method with a nominal [Al3+]/[Mg2+] ratio of 0.5 and a variable molar IBU/([Al3+]+[Mg2+]) ratio of 0, 0.15, 0.18, 0.24, 0.36, and 0.72. After an accurate determination of the composition, the nature of the intercalated species and the effective intercalation yield from to IBU, it is shown that the synthesis route used allows a good control of the quantity of intercalated IBU within the LDH framework. This results in different samples with full or partial IBU intercalation in the interlayer space in exchange of nitrate anions. The analysis of the X‐ray diffraction basal reflections reveals that the intercalation of IBU in the framework only increases the basal distances with no alteration of the brucite‐type layers. Also, a computational study used to model the positions and shapes of the basal reflections showed that the structure of the nonfully intercalated compounds follows a random interstratification scheme. Finally, three samples ranging from slightly to fully IBU‐intercalated galleries were selected for preliminary in vivo assays. These tests showed a strong tendency that after 24 hours the low yield of IBU‐intercalated compounds are almost as efficient as the fully intercalated sample. 相似文献
47.
向PVC糊状树脂中添加2-二置换氨基-4、6-二噻茂仲三嗪或其金属盐及水滑石等添加剂进行交联改性,可显著降低其溶胶粘度,提高透明性,改善加工耐热性。 相似文献
48.
Franois Malherbe C. Depge C. Forano J. P. Besse M. P. Atkins B. Sharma S. R. Wade 《Applied Clay Science》1998,13(5-6)
Layered double hydroxides (LDHs) are extensively studied as precursors for catalysts, following a calcination at high temperatures to yield mixed oxides. However, these materials are less used as layered materials, i.e., without undergoing thermal activation. We have focused in this work on the use of a series of as-synthesised LDHs for the catalytic preparation of glycol ethers, which is a reaction of primary commercial importance. Two main systems are considered, namely the [Cu–Cr] and [Mg–Al] LDHs. The [Cu–Cr–Cl] LDH is obtained by the coprecipitation method, then through the appropriate chimie douce exchange reactions the original chloride anions are replaced by a variety of oxo- and polyoxometallates, (CrO4)2−, (Cr2O7)2−, (V2O7)2−, (V10O28)6− and (Mo7O24)6−. On the other hand, the [Mg–Al] hydrotalcites, intercalated by (V2O7)2−, (V10O28)6− and [FeIII(CN)6]3− anions, are obtained by structure regeneration. This was done by rehydration of a commercial calcined material (Kyowa) in aqueous solutions containing the desired anion. The different materials have been fully characterised by conventional analytical techniques to evidence their lamellar properties and chemical nature. They were then tested in the catalytic reaction involving butan-1-ol and one or more units of ethylene oxide to make butyl-monoglycol ether (BMGE), di-glycol ether (BDGE), tri-glycol ether (BTGE), etc. The reactions were carried out between 80 and 120°C, temperature range in which no collapse of the lamellar structure is normally observed. In this paper it is shown that decavanadate exchanged LDHs proved to be very selective catalysts for the preparation of the monoglycol adduct, some samples achieving up to 100% selectivity in the screening tests. 相似文献
49.
S. Kannan 《Applied Clay Science》1998,13(5-6)
Catalytic decomposition of nitrous oxide into nitrogen and oxygen has been carried out on ‘in situ' thermally calcined hydrotalcites of general formula M(II)–M(III)-CHT where M(II)=Mg, Co, Ni, Cu or Zn and M(III)=Al, Fe or Cr having different M(II)/M(III) atomic ratios. The reaction was performed in a recirculatory static reactor at 50 Torr (133.3 Pa) initial pressure of N2O in the temperature range 423–773 K. Among the catalysts screened, Ni and Co containing catalysts with Al as the trivalent cation showed good activity (even at 423 K) wherein 50% and 100% conversion was achieved at 463 K and 523 K, respectively. Results on effect of composition for Co–Al system indicated that the activity increased with increase in the active metal ion concentration (Co2+), with closer dependence on the surface concentration (as determined by XPS). The observed activity pattern is explained on the basis of redox property and electronic effects. These materials were further evaluated under flow conditions (at Air Products and Chemicals, USA) simulating the industrial process streams (10% N2O, 2% H2O, 2% O2 and balance N2 and GHSV=18,500). Among the non-precious metal ions investigated, cobalt-based catalysts offered comparable activity similar to metal-exchanged zeolites for removing N2O from combustion and Nylon-6,6 processes. 相似文献
50.