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Förster T Schunk SA Jentys A Lercher JA 《Chemical communications (Cambridge, England)》2011,47(11):3254-3256
Co and Mn polysiloxanes are unique catalyst/initiator systems for the liquid phase oxidation of o-xylene showing higher activity than Co naphthenates, which is related to the weak interaction of the polar products with the hydrophobic surface as well as the absence of hydroxyl groups and surrounding oxygenates limiting radical quenching. 相似文献
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Chen Zhao Yuan Kou Prof. Dr. Angeliki A. Lemonidou Prof. Dr. Xuebing Li Dr. Johannes A. Lercher Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(22):3987-3990
Oil and water : A new energy‐efficient and atom‐economical catalytic route for the production of alkanes and methanol by upgrading the phenolic fraction of bio‐oil has been developed. The one‐pot aqueous‐phase hydrodeoxygenation process is based on two catalysts facilitating consecutive hydrogenation, hydrolysis, and dehydration reactions.
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Roberts VM Stein V Reiner T Lemonidou A Li X Lercher JA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(21):5939-5948
The products of base-catalyzed liquid-phase hydrolysis of lignin depend markedly on the operating conditions. By varying temperature, pressure, catalyst concentration, and residence time, the yield of monomers and oligomers from depolymerized lignin can be adjusted. It is shown that monomers of phenolic derivatives are the only primary products of base-catalyzed hydrolysis and that oligomers form as secondary products. Oligomerization and polymerization of these highly reactive products, however, limit the amount of obtainable product oil containing low-molecular-weight phenolic products. Therefore, inhibition of concurrent oligomerization and polymerization reactions during hydrothermal lignin depolymerization is important to enhance product yields. Applying boric acid as a capping agent to suppress addition and condensation reactions of initially formed products is presented as a successful approach in this direction. Combination of base-catalyzed lignin hydrolysis with addition of boric acid protecting agent shifts the product distribution to lower molecular weight compounds and increases product yields beyond 85%. 相似文献
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Z.M. Babar Wan Mohd Azizi Solachuddin JA Ichwan Qamar Uddin Ahmed Abul Kalam Azad Imranul Mawa 《Natural product research》2019,33(15):2266-2270
The current study provides a way of extraction for both active NSO and WSE from Nigella sativa seeds using 98% methanol. About 1?kg of ground seeds was macerated by 1:2.5 w/v (g/mL) for 72?hours. After rotary evaporation and 7 days of continuous drying and chilling at 50 and 4?°C, NSO and WSE were obtained at the same instant. Solubility tests of 24 solvents and 11 thin layer chromatographic analyses while 2, 2-diphenyl-1-picrylhydrazyl free radical scavenging assay of NSO (73.66) , WSE (33.32) and NSO?+?WSE (78.22) against ascorbic acid (IC50?=?4.28?mg/mL) was performed. WSE was found to be highly soluble in water and 5% NaOH exhibiting the same Rf value of 0.95 for EtOH:DMSO (9:1) against the honey. WSE has revealed more than twofold higher anti-oxidant activity than others. Formulation of WSE with Tualang honey may provide better targeted hydrophilic drug delivery systems. 相似文献
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Meng Wang Yuntao Zhao Donghai Mei R. Morris Bullock Oliver Y. Gutirrez Donald M. Camaioni Johannes A. Lercher 《Angewandte Chemie (International ed. in English)》2020,59(4):1445-1449
The hydrogenolysis of the aromatic C?O bond in aryl ethers catalyzed by Ni was studied in decalin and water. Observations of a significant kinetic isotope effect (kH/kD=5.7) for the reactions of diphenyl ether under H2 and D2 atmosphere and a positive dependence of the rate on H2 chemical potential in decalin indicate that addition of H to the aromatic ring is involved in the rate‐limiting step. All kinetic evidence points to the fact that H addition occurs concerted with C?O bond scission. DFT calculations also suggest a route consistent with these observations involving hydrogen atom addition to the ipso position of the phenyl ring concerted with C?O scission. Hydrogenolysis initiated by H addition in water is more selective (ca. 75 %) than reactions in decalin (ca. 30 %). 相似文献
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