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111.
Maria Jesus Yebra Jaime Arroyo Pascual Sanz Jose Antonio Prieto 《Applied biochemistry and biotechnology》1997,68(1-2):113-120
Bacillus polymyxa CECT 155 produces an extracellular neopullulanase activity that degrades pullulan to panose. This activity was stimulated
by the presence of pullulan in the culture, and repressed by glucose. The apparent mol wt determined for the enzyme was 58
kDa. The optimum pH and temperature for neopullulanase activity were pH 6.0 and 50°C, respectively. The enzyme was stable
in a pH range of 4.0–8.0, and temperatures up to 60°C. These properties make it suitable for the saccharification processes
in the starch industries. 相似文献
112.
Karl S. Noah Debby F. Bruhn Gregory A. Bala 《Applied biochemistry and biotechnology》2005,122(1-3):465-473
The biosurfactant surfactin has potential to aid in the recovery of energy resources (oil recovery) or subsurface organic
contaminants (environmental remediation). However, high medium and purification costs limit its use in these high-volume applications.
In previous work, we showed that surfactin could be produced from an inexpensive low-solids potato process effluent with minimal
amendments or pretreatments. Previous research has also shown that surfactin can be both produced in Bacillus subtilis cultures and recovered by foam fractionation in an airlift reactor. Results using both purified potato starch and unamended
low-solids potato process effluent as substrates for surfactin production indicate that the process is oxygen limited and
that recalcitrant indigenous bacteria in the potato process effluent hamper continuous surfactin production. The research
reported here features the use of a chemostat operated in batch mode for producing surfactin with concomitant use of antifoam
to prevent surfactant loss. The antifoam did not interfere with surfactin recovery by acid precipitation or its efficacy.
Initial trials took about 48 h to produce 0.9 g/L of surfactin from potato process effluent. Increasing the oxygen mass transfer
by increasing the stirring speed and adding a baffle decreased production time to 12–24 h and produced about 0.6 g/L of surfactin
from two different potato-processing facilities. 相似文献
113.
Kinetics of the Action of Na2SeO3 on Bacillus subtilis Growth as Studied by Microcalorimetry 总被引:6,自引:0,他引:6
Microcalorimetric bioassay for acute cellular toxicity is based on metabolic heat production from cultured cells.The biological response to toxicants is the inhibition of the heat production rate in cells,and toxicity is expressed as the concentration of toxicant that is 50% effective in this inhibition(IC50).In this paper,the effect of Na2SeO3 on Bacillus subtilis growth was investigated at 37℃ by microcalorimetry.The relationship between growth rate constants(k) and concentration of Na2SeO3(c) shows a logarithmic normal distribution,and IC50 is 20.3μg/mL.All these thermokinetic information is readily obtained by an LKB 2277-204 heat conduction microcalorimeter.Microcalorimetry is a quantitative,inexpensive,and versatile method for toxicology research. 相似文献
114.
Dirk Konz Andrea Klens Kurt Schörgendorfer Mohamed A. Marahiel 《Chemistry & biology》1997,4(12):927-937
Background: The branched cyclic dodecylpeptide antibiotic bacitracin, produced by special strains of Bacillus, is synthesized nonribosomally by a large multienzyme complex composed of the three bacitracin synthetases BA1, BA2 and BA3. These enzymes activate and incorporate the constituent amino acids of bacitracin by a thiotemplate mechanism in a pathway driven by a protein template. The biochemical features of these enzymes have been studied intensively but little is known about the molecular organization of their genes.Results: The entire bacitracin synthetase operon containing the genes bacA-bacC was cloned and sequenced, identifying a modular structure typical of peptide synthetases. The bacA gene product (BA1, 598 kDa) contains five modules, with an internal epimerization domain attached to the fourth; bacB encodes BA2 (297 kDa), and has two modules and a carboxy-terminal epimerization domain; bacC encodes BA3, five modules (723 kDa) with additional internal epimerization domains attached to the second and fourth. A carboxy-terminal putative thioesterase domain was also detected in BA3. A putative cyclization domain was found in BA1 that may be involved in thiazoline ring formation. The adenylation/thioester-binding domains of the first two BA1 modules were overproduced and the detected amino-acid specificity coincides with the first two amino acids in bacitracin. Disruption of chromosomal bacB resulted in a bacitracin-deficient mutant.Conclusions: The genes encoding the bacitracin synthetases BA1, BA2 and BA3 are organized in an operon, the structure of which reflects the modular architecture expected of peptide synthetases. In addition, a putative thiazoline ring formation domain was identified in the BA1 gene. 相似文献
115.
Effect of ethanol on the synthesis of large-ring cyclodextrins by cyclodextrin glucanotransferases 总被引:1,自引:0,他引:1
Qingsheng Qi Mohd Noriznan Mokhtar Wolfgang Zimmermann 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):95-99
Cyclodextrin glucanotransferase (EC 2.4.1.19, CGTase) synthesizes cyclodextrins (CD) composed of 6 to more than hundred glucose
units from amylose by an intramolecular transglycosylation reaction. The addition of ethanol to the reaction medium resulted
in an increase of the yield of large-ring CD obtained with a CGTase from Bacillus sp. BT3-2 and Bacillus macerans. The presence of 15% ethanol in the reaction mixture with the CGTase from Bacillus sp. BT3-2 resulted in a 30% increase of the amounts of CD10–CD13 synthesized after 5 h of reaction. The addition of 20% ethanol increased the yield of CD14–CD21 up to 1000%. The hydrolysis of the large-ring CD by the CGTases was suppressed in the presence of ethanol. The ring-opening
coupling cyclization reactions of the CGTase were effected differently by the organic solvent which may contribute to the
observed increase of the yield and size of the CD obtained in the synthesis reactions. 相似文献
116.
N. Latha Rani T. Prashanth H. D. Gurupadaswamy K. Shaukath Ara N. K. Lokanath 《Molecular Crystals and Liquid Crystals》2016,624(1):262-270
The title compound was synthesized by reacting 2-hydroxy-4-methoxy-benzaldehyde with diethyl malonate in the presence of piperidine catalyst and ethanol as solvent. The chemical structure of the title compound was elucidated by elemental analysis, 1H-NMR, and IR. The crystal structure was determined by X-ray diffraction data. It crystallizes in monoclinic crystal system, P21/c space group with unit cell parameters, a = 12.840(2) Å, b = 24.790(4) Å, c = 7.8544(13) Å, β = 98.035(5)°, V = 2475.5(7) Å3, and Z = 8. The molecular and crystal structure of the title compound is stabilized by inter- and intramolecular interactions of the type C—H···O. The newly synthesized compound was screened for its antibacterial activity against two gram-positive and two gram-negative bacteria. 相似文献
117.
Stratis-Cullum DN Griffin GD Mobley J Vo-Dinh T 《Analytical and bioanalytical chemistry》2008,391(5):1655-1660
This paper reports the first intensified biochip system for chemiluminescence detection and the feasibility of using this
system for the analysis of biological warfare agents is demonstrated. An enzyme-linked immunosorbent assay targeting Bacillus globigii spores, a surrogate species for Bacillus anthracis, using a chemiluminescent alkaline phosphatase substrate is combined with a compact intensified biochip detection system.
The enzymatic amplification was found to be an attractive method for detection of low spore concentrations when combined with
the intensified biochip device. This system was capable of detecting approximately 1 × 105
Bacillus globigii spores. Moreover, the chemiluminescence method, combined with the self-contained biochip design, allows for a simple, compact
system that does not require laser excitation and is readily adaptable to field use.
Figure Schematic diagram of the miniature biochip detection system 相似文献
118.
Two novel isocoumarins, bacilosarcins A (1) and B (2) were isolated from a culture broth of the marine-derived bacterium Bacillus subtilis TP-B0611. The structures and absolute configurations of 1 and 2 were determined on the basis of spectroscopic analyses and chemical conversions. Compound 1 possesses an unprecedented 3-oxa-6,9-diazabicyclo[3.3.1]nonane ring system while 2 has a 2-hydroxymorpholine moiety that is rare in nature. These compounds showed growth inhibition against barnyard millet. 相似文献
119.
120.
Production of Cyclodextrins by CGTase from Bacillus clausii Using Different Starches as Substrates 总被引:1,自引:0,他引:1
Alves-Prado HF Carneiro AA Pavezzi FC Gomes E Boscolo M Franco CM da Silva R 《Applied biochemistry and biotechnology》2008,146(1-3):3-13
Cyclodextrins (CDs) are cyclic oligasaccharides composed by d-glucose monomers joined by α-1,4-d glicosidic linkages. The main types of CDs are α-, β- and γ-CDs consisting of cycles of six, seven, and eight glucose monomers,
respectively. Their ability to form inclusion complexes is the most important characteristic, allowing their wide industrial
application. The physical property of the CD-complexed compound can be altered to improve stability, volatility, solubility,
or bio-availability. The cyclomaltodextrin glucanotransferase (CGTase, EC 2.4.1.19) is an enzyme capable of converting starch
into CD molecules. In this work, the CGTase produced by Bacillus clausii strain E16 was used to produce CD from maltodextrin and different starches (commercial soluble starch, corn, cassava, sweet
potato, and waxy corn starches) as substrates. It was observed that the substrate sources influence the kind of CD obtained
and that this CGTase displays a β-CGTase action, presenting a better conversion of soluble starch at 1.0%, of which 80% was
converted in CDs. The ratio of total CD produced was 0:0.89:0.11 for α/β/γ. It was also observed that root and tuber starches
were more accessible to CGTase action than seed starch under the studied conditions. 相似文献