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131.
Masahiro Yasuda Miho Kobayashi Shinji Watanabe Hiroyasu Ogino Kosaku Ishimi Haruo Ishikawa 《Journal of polymer science. Part A, Polymer chemistry》2002,40(7):874-884
To develop monodisperse amphiphilic polymer particles on which a large amount of lipase could be immobilized, we performed seed polymerizations of glycidyl methacrylate and allyl methacrylate in the presence of nonpolar inert and polar inert solvents. The amphiphilic porous polymer particles, which had both hydrophilic guanidino groups and hydrophobic stearoyl groups, were synthesized in the presence of n‐decane and had a large amount of macropores with diameters of 50–1000 nm. The amount of lipase immobilized on the amphiphilic particles synthesized in the presence of n‐decane was 3.85 times that of the lipase immobilized on the amphiphilic particles synthesized in the absence of a solvent. The immobilized lipase prepared with the amphiphilic particles synthesized in the presence of n‐decane exhibited a high transesterification activity in n‐hexane and could be used repeatedly without a considerable activity loss. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 874–884, 2002; DOI 10.1002/pola.10178 相似文献
132.
133.
Lipase Immobilized in Organic-Inorganic Matrices 总被引:1,自引:0,他引:1
Enzyme lipase was immobilized with ferrite powder and deposited in layers on glass slides from lipase to a solution of silicone alkoxides. The highest hydrolytical activity was observed with the magnetic lipase prepared by mixing the paste of ferrite powder and lipase with tetramethoxysilane, 3-aminopropyltriethoxysilane and propyltrimethoxysilane. In a mixed reactor, the particles of the magnetic lipase were desintegrated by mechanical stirring which caused loosing the lipase linked to magnetic material and resulted in a significant drop of activity after magnetic separation. Transparent layers were prepared by dip- or spin-coating from partially hydrolyzed tetraethoxysilane and solutions containing methyltriethoxysilane with 3-aminopropyltriethoxysilane or tetraethoxysilane with 3-mercaptopropyltriethoxysilane. The lipases immobilized in films with magnetic particles were active in tests with 4-nitrophenyl butyrate and were not inhibited by 0,0-dimethyl-0-(2,2-dichlor-vinyl)-phosphate. 相似文献
134.
Sánchez A De La Casa RM Sinisterra JV Valero F Sánchez-Montero JM 《Applied biochemistry and biotechnology》1999,80(1):65-75
Different fed-batch cultures of Candida rugosa were carried out using oleic acid as the only carbon source. The crude lipases obtained under several operational conditions
and downstream processes showed different catalytic activity and isoenzymes ratio. This fact implied that the performance
of the lipase produced could be modulated by using different operational fermentation conditions. These powders were compared
with commercial lipase from Sigma (St. Louis, MO) in hydrolysis and synthesis reactions. Especially interesting was the fact
that the enantioselectivity of a crude lipase was higher than that observed with commercial lipase in the resolution of recemic
Ketoprofen. In addition, response of both lipases in the presence of water was different. 相似文献
135.
Polysiloxane-encapsulated stationary phase for reversed-phase high-performance liquid chromatography
Summary Silica beads of 6-μm average diameter were silanized with methylvinyldiethoxysilane and then subjected to encapsulation with
poly(methylvinylsiloxane). The resulting product is a new stationary phase for reversed-phase high performance liquid chromatography
(RP-HPLC) which has superior ability for the separation of polar, non-polar and basic compounds. The chromatographic peaks
are symmetric. Its stability has been studied; after continuous use for three months the carbon content and chromatographic
behaviour of the phase were unchanged. on to the silica surface to given an uniform organic film. Material prepared in this
way has both good chromatographic behaviour and superior selectivity. Because contact of the silica matrix with the mobile
phase is avoided, the alkali-resisting ability of the stationary phase is increased. The non-specific adsorption of alkaline
solutes on to the silica surface is also avoided because of the complete coverage of surface silanol groups. Reports of stationary
phases encapsulated with polystyrene [6], polybutadiene [I] and octadecylsiloxane polymers have recently appeared in the literature
[3].
In this paper we report the encapsulation of poly-(methylvinylsiloxane) (analogous to the phase SE-31 often used in GC) on
to a silica matrix previously modified with methylvinyldiethoxysilane. The resulting phase has superior performance in reversed-phase
HPLC. 相似文献
136.
Immobilized PS-C ‘Amano’ II lipase was used to catalyze the interesterification of palm olein (POo) with 30, 50, and 70% stearic acid in n-hexane at 60°C. The catalytic performance of the immobilized lipase was evaluated by determining the composition change of
fatty acyl groups and triacylglycerol (TAG) by gas liquid chromatography and high-performance liquid chromatography, respectively.
The interesterification process resulted in the formation of new TAGs, mainly tripalmitin and dipalmitostearin, both of which
were absent in the original oil. These changes in TAG composition resulted in an increase in slip melting point, from the
original 25.5°C to 36.3, 37.0, and 40.0°C in the modified POo with 30, 50, and 70% stearic acid, respectively. All the reactions
attained steady state in about 6 h. This type of work will find great applications in food industries, such as confectionery. 相似文献
137.
Lipase-catalyzed amidation of 2-[2-(ethoxycarbonyl)ethyl]-1,1′-binaphthyl [(±)-3] yielded optically active (S)-3 and 2-[2-(2-cyanoethylaminocarbonyl)ethyl]-1,1′-binaphthyl [(R)-6a] with high enantiomeric excess. For these lipase-catalyzed amidations, the optimal alkyl chain length between the binaphthyl ring and the ester group was determined to be an ethylene spacer. 相似文献
138.
Leandro N. Monsalve 《Tetrahedron》2008,64(8):1721-1730
Lipase-catalyzed transesterification of the 20 hydroxyl group in a series of pregnanes afforded novel 20-ethyl succinates that are not possible to prepare following the traditional synthetic methods. The reaction is stereoselective. The enzyme reacts selectively with the 20β epimers therefore only the 20β-succinyloxy derivatives are obtained. These compounds are obtained in variable yield, depending on the substitution in the ring A. The enzymatic approach allowed, for the first time, the synthesis of 20β-hemisuccinyloxy-5αH-pregnan-3-one, novel compound useful as a precursor of steroid-protein conjugates. 相似文献
139.
Karla A. Barrera‐Rivera Ángel Marcos‐Fernández Ricardo Vera‐Graziano Antonio Martínez‐Richa 《Journal of polymer science. Part A, Polymer chemistry》2009,47(21):5792-5805
Yarrowia lipolytica (YLL), Candida rugosa (CRL), and porcine pancreatic lipase (PPL) were employed successfully as catalysts in the enzymatic ring‐opening polymerization (ROP) of ε‐caprolactone in the presence of 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ([EMIM][BF4]), 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIM][BF4]), 1‐butylpyridinium tetrafluoroborate ([BuPy][BF4]), 1‐butylpyridinium trifluoroacetate ([BuPy][CF3COO]), 1‐ethyl‐3‐methylimidazolium nitrate ([EMIM][NO3]) ionic liquids. Poly(ε‐caprolactone)s (PCLs) with molecular weights (Mn) in the range of 300–9000 Da were obtained. 1H‐ and 13C‐NMR analyses on PCLs formed by YLL, CRL, and PPL showed asymmetric telechelic α‐hydroxy‐ω‐carboxylic acid end groups. Differences between CP‐MAS and MAS spectra are observed and discussed in terms of morphology. MALDI‐TOF spectra show the formation of at least seven species. Differential scanning calorimetry (DSC) and Wide Angle X‐Ray Scattering (WAXS) results demonstrate the high degree of crystallinity present in all the polyesters. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5792–5805, 2009 相似文献
140.
A high-yielding three-step synthesis of goniothalamin involving an enzymatic kinetic resolution in the presence of vinyl acrylate followed by ring-closing metathesis is discussed. 相似文献