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排序方式: 共有496条查询结果,搜索用时 15 毫秒
1.
Mangoes (Mangifera indica) are grown in many warm regions of the world; for example, in Australia, Brazil, India, South America, and the United States (California and Florida), and along the shores of the Mediterranean sea (Egypt, Italy, and Spain). In Egypt, many varieties yielding delicious fruits are grown in large quantities (50,000 tons annually). Mango kernels are used for feeding mammals and chickens. Starch has been isolated from mango and its physical properties studied.The aim of the present work was to study the polysaccharides present in mango kernels. 相似文献
2.
Abdel-Halim Mahmoud Mohammed El-Sayed Hans Jürgen Rehm 《Applied microbiology and biotechnology》1987,26(3):211-214
Summary The growth rates of immobilized Penicillium chrysogenum strains are important in their application to semicontinuous penicillin production. Immobilized P. chrysogenum strains produced about 10–15% less biomass but about 1–2 times more penicillin than free suspended mycelia.In a chemically defined medium an industrial P. chrysogenum strain, S1, produced about 10–12 times more penicillin than strain ATCC 12690. In a complex medium the immobilized P. chrysogenum S1 produced about 12% penicillin more than in shaken cultures. In bubble column fermentations, penicillin production was 163% higher in the complex medium than in the chemically defined medium. 相似文献
3.
The ultrastructure of a lateral organ in the head of Polyxenus lagurus which has been recently erroneously termed cerebral gland is described. It turned out to be a neurohaemal organ and not a gland, apparently homologous to the organ of Gabe of the luliformia. 相似文献
4.
We have analyzed a total of 12 different global and local multiple
protein-sequence alignment methods. The purpose of this study is to
evaluate each method's ability to correctly identify the ordered series of
motifs found among all members of a given protein family. Four
phylogenetically distributed sets of sequences from the hemoglobin, kinase,
aspartic acid protease, and ribonuclease H protein families were used to
test the methods. The performance of all 12 methods was affected by (1) the
number of sequences in the test sets, (2) the degree of similarity among
the sequences, and (3) the number of indels required to produce a multiple
alignment. Global methods generally performed better than local methods in
the detection of motif patterns.
相似文献
5.
Moxifloxacin and ofloxacin are two broad-spectrum quinolone antibiotics. They are among the most widely used antibiotics, at this time, applied to control the COVID-19 pandemic. Hydroxychloroquine is an FDA-approved drug for the treatment of COVID-19. This work describes a simple, green, selective, and sensitive spectrofluorimetric method for the assay of moxifloxacin and ofloxacin in the presence of hydroxychloroquine, two co-administered mixtures used in the treatment of hospital-acquired pneumonia in patients with COVID-19. Simultaneous assay of hydroxychloroquine and moxifloxacin was carried out in methanol using a direct spectrofluorimetric method (method I) at 375 and 550 nm, respectively, after excitation at 300 nm. The direct spectrofluorimetric assay was rectilinear over concentration ranges 50.0–400.0 and 300.0–2500.0 ng/ml for hydroxychloroquine and moxifloxacin, respectively, with limits of detection (LOD) of 6.4 and 33.64 ng/ml and limits of quantitation (LOQ) of 19.4 and 102.6 ng/ml, respectively, for the two drugs. The assay for hydroxychloroquine and ofloxacin was carried out by measuring the first derivative synchronous amplitude for hydroxychloroquine at the zero crossing point of ofloxacin and vice versa at Δλ = 140 nm (method II). Hydroxychloroquine was measured at 266 nm, while ofloxacin was measured at 340 nm over the concentration range 4–40 ng/ml for hydroxychloroquine and 200–2000 ng/ml for ofloxacin with LOD of 0.467 and 25.3 ng/ml and LOQ of 1.42 and 76.6 ng/ml, respectively, for the two drugs. The two methods were validated following International Conference on Harmonization guidelines and were applied to the analysis of the two drugs in plasma with good percentage recoveries (109.73–93.17%). 相似文献
6.
Resonance Raman kinetic spectroscopy of bacteriorhodopsin on the microsecond time scale. 总被引:1,自引:0,他引:1
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Using a rotating disk with a slit of variable width, a continuous wave argon ion laser, and an Optical Multichannel Analyzer for detection, a new technique is reported which should, in principle, be capable of recording resonance Raman spectra with time resolution of 100 ns. The resonance Raman spectra of the intermediates of the photosynthetic cycle of bacteriorhodopsin are recorded on the microsecond time scale. Both the kinetic results and the resonance enhancement profile suggest that deprotonation results in an intermediate preceding bM412 that has an optical absorption maximum at a wavelength longer than that of bM412. 相似文献
7.
In vitro stimulation of alkaline phosphatase activity in immature embryonic chick pelvic cartilage by adenosine
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Cyclic AMP content in embryonic chick pelvic cartilage increases significantly as the embryo ages from 8 to 10 d. This in ovo elevation in cyclic AMP content precedes maximal cartilage alkaline phosphatase activity by some 24 h. We studied whether this temporal relationship may be causally related, using an in vitro organ culture. Incubation of pelvic cartilage from 9- and 10-d embryos in medium containing monobutyryl cyclic AMP (BtcAMP) resulted in significant increases in alkaline phosphatase activity (220 and 66 percent, respectively) as compared to that of cartilages incubated in medium alone. This stimulation was both concentration- and time-dependent with maximal response at 0.5 mM BtcAMP and 4-h incubation, respectively. Similar incubations of cartilage in medium containing 1-methyl-3-isobutyl xanthine (MIX), 0.25 mM, also resulted in increased alkaline phosphatase activity (114 percent). However, pelvic cartilage from 11-d embryos incubated in medium containing BtcAMP or MIX showed no increase in alkaline phosphatase activity. We postulated that developmental age was the factor responsible for this difference in response and that immature cartilage (that with little or no alkaline phosphatase activity) would respond to BtcAMP whereas mature cartilage (that with significant alkaline phosphatase activity) would not. This was tested by incubating end sections of 11-d cartilage, which have little alkaline phosphatase activity, and center sections, which have significantly alkaline phosphatase activity, with both BtcAMP and MIX. Alkaline phosphatase activity in end sections (immature cartilage) was stimulated by BtcAMP and MIX, whereas it was not stimulated in the center sections. Actinomycin D and cycloheximide inhibited BtcAMP and MIX stimulation of alkaline phosphatase activity. Thus, the in vitro data suggest that cyclic AMP is a mediator for the stimulation of alkaline phosphatase activity in embryonic cartilage. 相似文献
8.
Mohamed M. El-Sayed 《Carbohydrate research》1982,110(2):277-282
Polysaccharides of the brown seaweed Turbinaria murrayana were isolated. Laminaran (3.2%) was isolated from the hot-water extract of the algae by using ion-exchange chromatography. Fucans (2.1%) were isolated from the hot-water extract, as well (4.7%) as from the extract of the algae with dilute acid. Acid hydrolsysis of the isolated fucans revealed glucose, amnnose, fucose, glucuronic acid, xylose, and galactose. Alginic acid (22.6%) was separated, and reduced to a neutral polysaccharide. The polysaccharides isolated were analyzed by methylation and Smith degradation. 相似文献
9.
Subpicosecond resonance Raman spectra of the early intermediates in the photocycle of bacteriorhodopsin 总被引:2,自引:1,他引:1
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R. van den Berg Du-Jeon-Jang Herbert C. Bitting M. A. El-Sayed 《Biophysical journal》1990,58(1):135-141
The resonance Raman spectra are presented for the species formed during the photocycle of bacteriorhodopsin (bR) on a timescale of 800-900 fs. In the ethylenic stretch region two intermediates were found with frequencies of 1,510 and 1,518 cm-1, corresponding to species with optical absorption maxima at 660 and 625 nm, respectively. This leads to the assignment of the 1,518 cm-1 band to the J625 intermediate. In the fingerprint region, the appearance of a vibration at 1,195 cm-1 strongly suggests that the isomerization indeed has taken place in a time less than the pulsewidth of our laser. This supports the previous proposals made on the basis of the optical spectra. The spectra are compared with those observed in tens of picoseconds up to nanoseconds. 相似文献
10.
The cyclic, semicontinuous production of L-phenylacetyl carbinol (L-PAC) from a benzaldehyde substrate by Saccharomyces cerevisiae ATCC 834 immobilized in calcium alginate beads was substantially enhanced to about 4.5 g/L in a second cycle by reactivation in fresh medium for 24 h, following an earlier 24-h period of production from substrate. Intermittent feeding of benzaldehyde was employed (four doses in 3 h). In subsequent similar cycles, however, the production returned to that produced in the first cycle, viz. L-PAC concentration of 2-3 g/L in the medium. Production of L-PAC was also increased by adaptation of the cells over 200 h of exposure to the benzaldehyde substrate (compared to wild-type cells) and by continuous (as compared to intermittent) feeding of the substrate. A liter as great as 10 g/L was obtained with wild-type cells by continuous feeding of benzaldehyde over 6 h. Immobilization not only protected the cells from toxic effects of substrate but also permitted them to be used during 7 cycles of semicontinuous operation over more than 200 h. 相似文献