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371.
The secondary reaction of toluene is difficult to be suppressed in benzene alkylation with methanol over conventional acidic zeolite catalysts. Moreover, the formation of coke yet remains a challenging problem. In this study, Na-Y zeolites were modified with ammonium carbonate (AC), citric acid (CA) and caesium nitrate(CN) to evaluate the alkylation of benzene with methanol, which was also characterized by XRD, SEM, FT-IR, N2 adsorption and Py-IR. For the Na-Y treated with AC-CA-CN, not only the catalytic selectivity for the alkylation of benzene with methanol was improved (the total selectivity of toluene and xylene was 97.9% and toluene selectivity was 86.4%), but also the quantity of coke was greatly decreased. 相似文献
372.
Sonication‐Aided Formation of Hollow Hybrid Nanoparticles as High‐Efficiency Absorbents for Dissolved Toluene in Water
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A surfactant‐free emulsion polymerization process was developed to produce hollow hybrid nanoparticles (HHNP thereafter). Ultrasonication was found not only to help the generation of nanosized monomer droplets but also to generate surface active species through mediating the hydrolysis of the monomer, 3‐(methacryloyloxy) propyltrimethoxysilane (MPS), thus stabilizing the oil/water interface. The hollow structure was formed based on a soft template approach, where the partially hydrolyzed monomer served as emulsifier and polymerized at the interface to form a hybrid shell. These HHNPs were used to absorb dissolved toluene in water and it was found they could reduce the toluene level down to zero, a level hardly being achieved by other methods. Combined with their good colloidal stability in water, these HHNPs are very promising colloidal collectors for dissolved organic solvents, in order to generate high quality water from contaminated water. 相似文献
373.
Anodized TiO2 nanotube fibers using in-headspace solid-phase microextraction (SPME) with gas chromatography–mass spectrometry (GC–MS) have been exploited as an analytical method for volatile organic compounds such as benzene, toluene, ethylbenzene, and xylenes (BTEX) detection. The factors of anodizing time and annealing temperature for TiO2 nanotube production are studied and the adsorption factors (time, ionic strength, and temperature) and desorption factors (time and temperature) for BTEX analysis are optimized. The limit of detections (LODs) for benzene, toluene, ethylbenzene o-xylene, and m, p-xylene are 0.5, 0.1, 1.0, 1.0, and 2.0 μg L−1, respectively. The linear ranges for BTEX (0.5–15,000 μg L−1) and satisfactory linearity (R2 ≥ 0.9954) are obtained. This method is successfully applied in real samples with the recoveries ranging from 92% to 97%. TiO2 nanotube fiber is a promising technique for BTEX analysis. 相似文献
374.
Piyabutr Sunsap Dong-Joo Kim Tawatchai Charinpanitkul Kyo-Seon Kim 《Research on Chemical Intermediates》2008,34(4):319-329
TiO2 nanoparticles were produced in the diffusion flame reactor, and the size and anatase/rutile content of TiO2 were examined by a Particle Size Analyzer and X-ray diffraction, respectively. Increase in fuel/O2 ratio, initial concentration of TiCl4 or total gas flow rate causes the larger particle size and the higher rutile composition. The photocatalytic activities of
TiO2 powders were tested on the decompositions of phenol and toluene in the aqueous solution under UV irradiation. The degradation
rate increases as the TiO2 particle size decreases and as the initial concentration of phenol or toluene increases. The photodegradation rate of phenol
by TiO2 particles is higher than that of toluene at the same process conditions. The computational method was used to simulate the
gas temperature, velocity and species mass fractions inside the diffusion flame reactor during synthesis of TiO2 nanoparticles. The measured and simulated temperature results were compared on several positions above the burner and both
of them show good agreements. The typical contours of TiCl4, TiO2 mass fractions and gas velocities in flame reactor were presented. 相似文献
375.
采用浸渍法制备了Pd/Ce0.8Zr0.2O2/基底整体催化剂,应用热重-差示扫描量热、扫描电镜、X射线衍射、氮吸附、拉曼光谱和程序升温还原等技术手段对催化剂进行了表征,考察了不同温度焙烧的整体催化剂的甲苯催化燃烧性能.结果表明,一层均匀紧密的Ce0.8Zr0.2O2涂层很好地分散在基底表面上,该涂层具有良好的抗振荡性和较高的粘结强度.400℃焙烧的Pd/Ce0.8Zr0.2O2/基底整体催化剂的催化活性最高,甲苯转化率达97%以上的最低反应温度为210℃.此外,Pd/Ce0.8Zr0.2O2/基底整体催化剂具有良好的热稳定性,这可能是因为CeO2-ZrO2固溶体的形成和高温下PdO的稳定存在. 相似文献
376.
I. A. Romanskii 《Russian Chemical Bulletin》2008,57(9):1842-1849
A mechanism is proposed of intramolecular reorganization leading to equalization of the energies of reactants and products
in a nonequilibrium proton transfer reaction. The model proposed allows one to extend a conventional quantum chemical treatment
to gas-phase proton transfer. Taking the reaction of toluene deprotonation with the CH2CN− anion (a conjugate base of acetonitrile) as an example, it was shown that the activation energy and its components can be
determined from direct ab initio calculations. The effect of disbalance of structural changes relative to the “equilibrium” proton transfer is considered.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1808–1815, September, 2008. 相似文献
377.
378.
Hydrogen production by catalytic reforming of simulated hot coke oven gas (HCOG) with toluene as a model tar compound was investigated in a fixed bed reactor over Ni/Mg(Al)O catalysts. The catalysts were prepared by a homogeneous precipitation method using urea hydrolysis and characterized by ICP, BET, XRD, TPR, TEM and TG. XRD showed that the hydrotalcite type precursor after calcination formed (Ni, Mg)Al2O4 spinel and Ni-Mg-O solid solution structure. TPR results suggested that the increase in Ni/Mg molar ratio gave rise to the decrease in the reduction temperature of Ni2+ to Ni0 on Ni/Mg(Al)O catalysts. The reaction results indicated that toluene and CH4 could completely be converted to H2 and CO in the catalytic reforming of the simulated HCOG under atmospheric pressure and the amount of H2 in the reaction effluent gas was about 4 times more than that in original HCOG. The catalysts with lower Ni/Mg molar ratio showed better catalytic activity and resistance to coking, which may become promising catalysts in the catalytic reforming of HCOG. 相似文献
379.
Seyed Ali HOSSEINI Mohammad Taghi SADEGHI Abdolali ALEMI Aligholi NIAEI Dariush SALARI Leila KAFI-AHMADI 《催化学报》2010,31(7):747-750
Nanostructured LaFeO3 and substituted LaZnxFe1-xO3 (x = 0.01, 0.05, 0.1, 0.2, and 0.3) perovskites were synthesized by the sol-gel auto-combustion method and used in the catalytic combustion of toluene. Their structures and surface properties were investigated by X-ray diffraction, Fourier transmission infrared spectroscopy, BET surface area, and scanning electron microscopy. Characterization data revealed that the total insertion of zinc into LaFeO3 takes place when x ≤ 0.1. However, ZnO segregation occurs to some extent, especially at x > 0.1. The performance of these perovskites was evaluated by toluene combustion. The catalytic activity of the catalysts increased substantially with an increase in zinc substitution. These results can be attributed to the cooperative effect between LaZnxFe1-xO3 and the zinc oxide phases. The relative concentration of these phases determines their oxygen activation ability and reactivity. 相似文献
380.
A simple and novel SPE system for benzene, toluene, ethylbenzene, and xylene isomers (BTEX) compounds in water is proposed in which samples are directly propelled from a 15 mL glass vial through a sorbent column by means of a needle, thereby avoiding evaporative losses and the sorption of BTEX on the manifold materials. Following elution with 150 microL of ethyl acetate, 1 microL of extract is injected into a gas chromatograph-mass spectrometer system. A comparative study of various sorbent materials (C60 fullerene, Tenax TA, and RP-C18) revealed C60 fullerene to be the best choice in terms of sensitivity (a likely result of its increased sample breakthrough volume), precision (the surfactant medium used to prepare samples minimizes evaporative losses), selectivity (C60 fullerene only interacts with nonpolar aromatic compounds), and reusability (columns containing 60 mg of C60 fullerene remain serviceable for at least 6 months). This C60 fullerene-based method exhibits a linear range of 0.1-100 microg/L, a detection limit of 0.04 microg/L, and an RSD of ca. 3%. It was applied to the determination of BTEX in various types of water including sea and waste water with good precision. 相似文献