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181.
182.
Aneeqa Sabah Prabhat Kumar Waleed S. Mohammed Joydeep Dutta 《Particle & Particle Systems Characterization》2013,30(5):473-480
A directional point‐to‐point growth of microwires of gold nanoparticles (AuNPs) self‐organized on Aspergillus niger (A. niger) templates by utilizing positive phototropic fungal response to different spectral ranges of visible light is reported. A. niger serves as a living template for the self‐organization of monosodium glutamate (MSG) capped gold colloids under controlled nutrient trigger and appropriate light, temperature, and humidity conditions. The experimental results show that control of these parameters eliminates the need for any microchannels for the directional growth of microwires. The growth rate of fungal hyphae increases exponentially under light illumination compared to its growth in the dark under similar conditions. White light is found to be most suitable to trigger the directional growth. Gold microwires of about 1 to 2 μm diameter and length exceeding 1 mm are grown within a week with a maximum divergence of 40–50° from the light path regardless of the wavelength of the light irradiation. Phototropic response of fungi has been investigated intensively over the last three decades, but this is the first report on the collective use of microbial tropism and directed biomimetic self‐organization of metallic nanoparticles on living organisms. 相似文献
183.
Rodrigues C Vandenberghe LP Teodoro J Pandey A Soccol CR 《Applied biochemistry and biotechnology》2009,158(1):72-87
Citric acid (CA) production has been conducted through a careful strain selection, physical–chemical optimization and mutation.
The aim of this work was to optimize the physical–chemical conditions of CA production by solid-state fermentation (SSF) using
the Aspergillus niger LPB BC strain, which was isolated in our laboratory. The parental and mutant strain showed a good production of CA using
citric pulp (CP) as a substrate. The physical–chemical parameters were optimized and the best production was reached at 65%
moisture, 30 °C and pH 5.5. The influence of the addition of commercial and alternative sugars, nitrogen sources, salts, and
alcohols was also studied. The best results (445.4 g of CA/kg of CP) were obtained with sugarcane molasses and 4% methanol
(v/w). The mutagenesis induction of LPB BC was performed with UV irradiation. Eleven mutant strains were tested in SSF where two
mutants showed a higher CA production when compared to the parental strain. A. niger LPB B3 produced 537.6 g of CA/kg of CP on the sixth day of fermentation, while A. niger LPB B6 produced 616.5 g of CA/kg of CP on the fourth day of fermentation, representing a 19.5% and 37% gain, respectively. 相似文献
184.
Fang Liu Gang Chen Li-hua Zhang Bing Liu Shaofei Chen Huiming Hua 《Natural product research》2018,32(1):30-35
A new diphenyl ether 3-methylpentyl-2, 4-dichloroasterrate (2), along with a known diphenyl ether butyl 2, 4-dichloroasterrate (1) were isolated from the metabolites of a wetland fungus Aspergillus flavipes. PJ03-11. The structures of 1 and 2 were determined by extensive NMR and HR–ESI–MS experiments. Compounds 1 and 2 showed weak cytotoxic activity, but both of them showed no antimicrobial activity. 相似文献
185.
The successful translation from conception to practice of processes based on immobilized biocatalyst technology has been slower
than anticipated. There are severe barriers, both technical and economic, limiting the introduction of immobilized biocatalyst
technology to replace conventional processing procedures and processes for the production of chemicals by synthetic or fermentative
routes. A small number of immobilized enzyme processes are in operation commercially, the most noteworthy being in food-related
processes and in the pharmaceutical industry, where they are used for carbohydrate conversions and antibiotic transformations,
respectively. There does not, as yet, appear to be any large-scale industrial application of immobilized cell technology.
Examples from our laboratory—immobilized yeast for ethanol production andAspergillus niger for citric acid synthesis—illustrate the problems that have to be overcome. 相似文献
186.
Protoplast fusion, induced by polyethylene glycol and Ca2+, was carried out between two auxotrophic strains ofAspergillus niger. The fusion frequency ranged from 6.2 × 10-2-9.1 × 10-2. After induced haploidization of a diploid, various segregants showing combinations of the parental genetic markers were
isolated. Unlike diploids, haploid segregants exhibited greater variations in their morphology and β-glucosidase activities.
One segregant showed a 2.5-fold increase in β-glucosidase activity over those of the parents. Thus, this method appears promising
for creating new recombinant strains ofA. niger with improved β-glucosidase activities. 相似文献
187.
A method to determine phytic acid in the range 3–60 μM based on the spectrophotometric determination of inorganic phosphate with vanadate and molybdate, after liberation by enzymatic hydrolysis of phytic acid with phytase from Aspergillus ficuum at pH 2.5 and 37 °C is reported. The method has been applied successfully to determine phytic acid in wheat flour and in a pharmaceutical product. 相似文献
188.
Silvana T. Silveira Melissa S. Oliveira Jorge A. V. Costa Susana J. Kalil 《Applied biochemistry and biotechnology》2006,128(2):131-139
Glucoamylase production by Aspergillus niger in solid-state fermentation was optimized using factorial design and response surface techniques. The variables evaluated
were pH and bed thickness in tray, having as response enzyme production and productivity. The bed thickness in tray was the
most significant variable for both responses. The highest values for glucoamylase production occurred using pH 4.5 and bed
thickness in the inferior limits at 2.0–4.2 cm. For productivity, the optimal conditions were at pH 4.5 as well and bed thickness
from 4.4 to 7.5 cm. The optimal conditions for glucoamylase production while obtaining high activity without loss of productivity
were pH 4.5 and bed thickness in tray from 4.0 to 4.5 cm, which resulted in an enzyme production of 695 U/g and productivity
of 5791 U/h. 相似文献
189.
Emri T Molnár Z Pusztahelyi T Rosén S Pócsi I 《Applied biochemistry and biotechnology》2004,118(1-3):337-348
The morphologic and physiologic effects of vitamin E, a powerful antioxidant, on the autolysis and sporulation of Aspergillus nidulans FGSC26 were studied. In carbon-depleted submerged cultures, reactive oxygen species (ROS) accumulated in the cells and, concomitantly,
progressing autolysis was observed, which was characterized by decreasing dry cell masses and pellet diameters as well as
by increasing extracellular chitinase activities. Vitamin E supplemented at a concentration of 1 g/L hindered effectively
the intracellular accumulation of ROS, the autolytic loss of biomass, the disintegration of pellets, and the release of chitinase
activities. In surface cultures, vitamin E inhibited autolysis of both A. nidulans FGSC26 and a loss-of-function FlbA autolytic phenotype mutant. In addition, supplementation of the culture medium with this antioxidant also had a negative
effect on the sporulation of strain FGSC26 and the FadA
G203R
hypersporulating phenotype mutant. These results suggest that accumulation of ROS was involved in the initiation of both
sporulation and autolysis in this filamentous fungus, but that FadA/FlbA signaling was not involved in this vitamin E-dependent
regulation. Vitamin E can be recommended as a supplement in fermentations in which the disintegration of pellets and gross
autolysis should be avoided. 相似文献
190.
Réczey K. Brumbauer A. Bollók M. Szengyel Zs. Zacchi G. 《Applied biochemistry and biotechnology》1998,(1):225-235
Hydrolysis of cellulose byTrichoderma cellulases often results in a mixture of glucose, cellobiose, and low-mol-wt cellodextrins. Cellobiose is nonfermentable
for most yeasts, and therefore it has to be hydrolyzed to glucose by β-glucosidase prior to ethanol fermentation. In the present
study, the β-glucosidase production of onePenicillium and threeAspergillus strains, which were previously selected out of 24 strains, was investigated on steam pretreated willow. Both steam-pretreated
willow and hemicellulose hydrolysate, released during steam explosion of willow, were used as carbon sources. Reference cultivation
runs were performed using prehydrolyzed Solka Floc and glucose: The four strains were compared withTrichoderma reesei regarding sugar consumption and β-glucosidase production.Aspergillus niger andAspergillus phoenicis proved to be the best enzyme producers on hemicellulose hydrolysate. The maximum β-glucosidase activity, 4.60 IU/mL, was
obtained whenA. phoenicis was cultivated on the mixture of hemicellulose hydrolysate and steam-pretreated willow. The maximum yield of enzyme activity,
502 IU/g total carbohydrate, was obtained whenAspergillus foetidus was cultivated on the hemicellulose hydrolysate. 相似文献