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381.
Methylmercury as well as mercury (II) were found to be effective inhibitors of the catalytic activity of alcohol dehydrogenase
from baker’s yeast in the reaction of ethanol oxidation by nicotinamide adenine dinucleotide. It was stated that the methylmercury
inhibitory action belonged to the non-competitive type, whereas Hg(II) inhibited the enzyme according to the mixed type. The
inversely proportional dependence of the indicator reaction rate on the concentration of methylmercury allowed to develop
an enzymatic procedure for its determination with a detection limit of 3 nM. The possibility of methylmercury determination
in presence of mercury (II) and mercury (II) determination in presence of methylmercury (concentration ratios CH3Hg+:Hg(II) were 1:1 and 1:10, respectively) was shown. In the first case masking reagents, DEDTC or thiourea, were used to form
stable complexes with Hg(II).
Received February 9, 2001; accepted August 10, 2001; published online June 24, 2002 相似文献
382.
Ethan S. Simon Raymond Plante George M. Whitesides 《Applied biochemistry and biotechnology》1989,22(2):169-179
This note compares the substrate specificity of D-lactate dehydrogenase (D-LDH, EC 1.1.1.28) to that of L-lactate dehydrogenase (L-LDH, EC 1.1.1.27), illustrates three procedures that use D-LDH in synthesis and two methods for recycling NADH, and provides experimental details illustrating the use of D-LDH in organic synthesis. 相似文献
383.
Rapid and well-reproducible methods were developed for the determination of aldose reductase and sorbitol dehydrogenase. The aldose reductase activity measurement is based on photometric o-toluidine aldose back-measurement, which is widely used in laboratories for the quantitative determination of glucose. The spectrophotometric method based on the quantitative decrease in NADH proved suitable for the measurement of sorbitol dehydrogenase activity.Both methods could well be employed for the measurement of the aldose reductase and sorbitol dehydrogenase activities of normal and diabetic tissue homogenizates, and for the comparison of the measured values. 相似文献
384.
A method for the convenient and reliable preparation of magnetizable agarose beads containing iron particles is described. The beads were treated with the triazine dye, Reactive Red 120, and the matrix was examined for the ability to extract proteins from crude preparations using lactate dehydrogenase from porcine muscle as a model. The recovery and specific activity values of enzyme obtained using this matrix and magnetic field separation were significantly greater than those for enzyme purified by centrifugation and conventional dye ligand chromatography. 相似文献
385.
In this study, a flow injection analysis (FIA) system using a cartridge of immobilized isocitrate lyase (ICL) and isocitrate dehydrogenase (ICDH) was developed to monitor the concentrations of succinic acid in biotechnological processes. The ICL and ICDH immobilized on VA-Epoxy Biosynth E3-carrier had a good operational lifetime (up to 24 h) and storage stability (up to 30 days). The FIA system with the immobilized ICL/ICDH cartridge was characterized with respect to the factors affecting the activity of the immobilized enzymes, such as pH of carrier solution, temperature, sample matrix, etc. Optimal pH value of the immobilized enzymes was slightly shifted in the alkaline range, i.e. 9.0. Some components such as 10 g l−1 lactose, 3 g l−1 malate and 3 g l−1 oxaloacetate in sample solution had significant activating effects (more than 10%) on the response of the FIA system. But the activity of the immobilized ICL and ICDH was not largely influenced by some components like imidazole (1 mM), sodium azide (10 mM) and semicarbazide (2 g l−1) added to carrier buffer solution. The FIA system with an enzyme cartridge was applied to on-line monitor the concentrations of succinic acid in a continuously stirred reactor and a fermentation process of immobilized Escherichia coli, and showed good sensitivity and reliability of the FIA system developed in this work. 相似文献
386.
《Electroanalysis》2005,17(1):73-78
The performance of enzymatic biosensors based on the immobilization of different enzymes within a carbon nanotubes paste electrode (CNTPE) prepared by dispersion of multi‐wall carbon nanotubes (MWNT) and mineral oil is reported in this work. The strong electrocatalytic activity of carbon nanotubes towards the reduction of hydrogen peroxide and quinones and the oxidation of NADH have allowed an effective low‐potential amperometric determination of lactate, phenols, catechols and ethanol, in connection with the incorporation of lactate oxidase, polyphenol oxidase and alcohol dehydrogenase/NAD+, respectively, within the composite matrix. Compared to the analogous enzymatic CPEs, a great enhancement in the response is observed at the enzymatic CNTPEs. Therefore, highly sensitive lactate, phenols, catechols and alcohols biosensors without using any metal or redox mediator can be obtained with this new composite material. 相似文献
387.
Sanghamitra Parida Ravindra Datta Jonathan S. Dordick 《Applied biochemistry and biotechnology》1992,33(1):1-14
The use of partially hydrated porous silica particles has been studied as a support for cofactor-dependent enzymatic catalysis
in organic solvents. At an optimal pore hydration corresponding to 70% pore volume, horse liver alcohol dehydrogenase catalyzes
the oxidation and reduction of alcohols and aldehydes, respectively, with rates sixfold higher than with nonporous glass beads
as the enzymatic support and with cofactor recycling numbers in excess of 105. Thus, supported aqueous-phase enzymatic catalysis makes highly effective use of the enzyme and cofactor by coimmobilization
and by providing a high interfacial area for reactions in organic media. 相似文献
388.
A fluorometric coupled enzymatic method for the determination of pyrophosphate is described. The kinetic method can determine pyrophosphate in amounts as low as 0.5 pmol. Intra- and interassay CV's were both less than 1% and recoveries were found to be quantitative. No significant interference was observed from EDTA, heparin, magnesium, or calcium. Correlation with an established method was significant (r = 0.87).Clinical studies of the applicability of the procedure were demonstrated by the measurement of pyrophosphate in plasma and platelets. Mean pyrophosphate levels in plasma and platelets of “normal” subjects were found to be 3.27 ± 0.2 μM and 2.40 ± 0.10 nmol/108 platelets or 17.59 ± 1.44 nmol/mg platelet protein, respectively.Pyrophosphate levels in plasma and platelets of patients on hemodialysis were determined and found to be significantly lower than the “normal” population. This finding may in part explain the occurrence of metastatic calcification seen in this patient population. 相似文献
389.
《Analytical letters》2012,45(13):2363-2373
Abstract We demonstrated a direct electron transfer-type enzyme electrode using thermostable FAD-glucose dehydrogenase (FADGDH) consisting of three distinct subunits (an FAD-containing catalytic subunit, a cytochrome subunit, and a chaperone-like subunit) and its application in developing a continuous glucose monitoring (CGM) system without a synthetic electron mediator. An FADGDH-immobilized electrode showed current signals according to glucose concentration in the absence of a synthetic electron mediator. The sensor containing the FADGDH complex showed a stable response for 72 h at 37°C. Furthermore, the CGM response was well fitted to the gradient change in the glucose concentration obtained from system calibration. 相似文献
390.
The in vitro and in vivo effects of corn peptides(CPs) prepared from corn gluten meal by proteolysis with an alkaline protease and fractions of CPs from Sephadex G-15 and G-10 columns on activities of alcohol dehydrogenase(ADH) were studied. The results show that CPs and fraction 3 of CPs from Sephadex G-10 column enhance in vitro ADH activity. Furthermore, the in vitro accelerating effect of the fraction 3 of CPs on ADH activity was superior to that of glutathione, which was also found even in the presence of ADH inhibitor, such as pyrazole. In the in vivo experiments, the animals were fed with different dosages of CPs and with a dose of Chinese distilled spirit orally, and sacrificed for the measurement of ADH activity. In vivo experimental results indicate that CPS enhanced hepatic ADH activities. To test the safety of CPs as health food, 30 d feeding test was performed. No obvious toxic effects were detected in treated Wistar rats. 相似文献