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201.
Suhong Zhang Jie Cheng Ying Liu Liang Xu Mark L. Trudell Sari Izenwasser Dean Wade 《Journal of heterocyclic chemistry》2007,44(6):1425-1430
A series of diol di‐(tropane‐3α‐carboxylate) esters and diol di‐(tropane‐3β‐carboxylate) esters were synthesized from 3‐tropene‐3‐carboxylic acid and tropane‐3β‐carboxylic acid, respectively. The bivalent tropane‐3‐carboxylates were evaluated for their ability to inhibit [3H]cytisine binding at rat brain nicotinic acetylcholine receptors (nAChRs). In general the (3β,3β')‐isomers were more potent than (3α,3α')‐isomer and the (3β,3β')‐decyl derivative (n = 10, Ki = 145 nM) exhibited the most potent affinity for nAChRs of the series. 相似文献
202.
Jussi Kasanen Janne Salstela Mika Suvanto Tuula T. Pakkanen 《Applied Surface Science》2011,258(5):1738
A multilayer photocatalytic TiO2 coating on a high-density polyethylene (HDPE) disk was found to degrade aqueous methylene blue in a batch reactor study. The TiO2 coating was fabricated by a low-temperature method using polyurethane resin (PU) as a barrier layer for HDPE and as a binding agent for two TiO2 layers. Adequate adhesion between the HDPE substrate and PU barrier in aqueous environment was ensured with an oxygen plasma treatment.The photocatalytic effect of immersed TiO2 coating on the degradation of methylene blue in aqueous solution was monitored by UV–vis spectrometry as a function of UV-illumination time. Samples were allowed to adsorb methylene blue in the dark for 1 h before the UV-degradation experiments were started. The percentages of methylene blue degraded during 6 h UV illumination (λ = 365 nm) varied from 80% to 92%. The degradation followed pseudo-first order reaction kinetics, and the observed rate constants (kobs) were between 0.27 and 0.43 h−1. 相似文献
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205.
Anak Agung Istri Ratnadewi Muchzainal Fanani Sari Dewi Kurniasih Makiko Sakka Eddy Bagus Wasito Kazuo Sakka Zeily Nurachman Ni Nyoman Tri Puspaningsih 《Applied biochemistry and biotechnology》2013,170(8):1950-1964
The gene encoding a thermostable β-d-xylosidase (GbtXyl43B) from Geobacillus thermoleovorans IT-08 was cloned in pET30a and expressed in Escherichia coli; additionally, characterization and kinetic analysis of GbtXyl43B were carried out. The gene product was purified to apparent homogeneity showing M r of 72 by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The enzyme exhibited an optimum temperature and pH of 60 °C and 6.0, respectively. In terms of stability, GbtXyl43B was stable at 60 °C at pH 6.0 for 1 h as well as at pH 6–8 at 4 °C for 24 h. The enzyme had a catalytic efficiency (k cat/K M) of 0.0048?±?0.0010 s?1 mM?1 on p-nitrophenyl-β-d-xylopyranoside substrate. Thin layer chromatography product analysis indicated that GbtXyl43B was exoglycosidase cleaving single xylose units from the nonreducing end of xylan. The activity of GbtXyl43B on insoluble xylan was eightfold higher than on soluble xylan. Bioinformatics analysis showed that GbtXyl43B belonging to glycoside hydrolase family 43 contained carbohydrate-binding module (CBM; residues 15 to 149 forming eight antiparallel β-strands) and catalytic module (residues 157 to 604 forming five-bladed β-propeller fold with predicted catalytic residues to be Asp287 and Glu476). CBM of GbtXyl43B dominated by the Phe residues which grip the carbohydrate is proposed as a novel CBM36 subfamily. 相似文献
206.
Sari MM 《Applied biochemistry and biotechnology》2011,163(8):1020-1037
Cupric ion-chelated poly(hydroxyethyl methacrylate-n-vinyl imidazole) (poly(HEMA-VIM)) microspheres prepared by suspension polymerization were investigated as a specific adsorbent
for immobilization of yeast invertase in a batch system. They were characterized by scanning electron microscopy, surface
area, and pore size measurements. They have spherical shape and porous structure. The specific surface area of the p(HEMA-VIM)
spheres was found to be 81.2 m2/g with a size range of 70–120 μm in diameter, and the swelling ratio was 86.9%. Then, Cu(II) ion chelated on the microspheres
(546 μmol Cu(II)/g), and they were used in the invertase adsorption. Maximum invertase adsorption was 51.2 mg/g at pH 4.5.
Cu(II) chelation increases the tendency from Freundlich-type to Langmuir-type adsorption model. The optimum activity for both
free and adsorbed invertase was observed at pH 4.5. The optimum temperature for the poly(HEMA-VIM)/Cu(II)-invertase system
was found to be at 55 °C, 10 °C higher than that of the free enzyme at 45 °C. V
max values were determined as 342 and 304 U/mg enzyme, for free and adsorbed invertase, respectively. K
m values were found to be same for free and adsorbed invertase (20 mM). Thermal and pH stability and reusability of invertase
increased with immobilization. 相似文献