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排序方式: 共有224条查询结果,搜索用时 31 毫秒
31.
Kamoun F Fguira IB Hassen NB Mejdoub H Lereclus D Jaoua S 《Applied biochemistry and biotechnology》2011,165(1):300-314
This study reports on the identification, characterization and purification of a new bacteriocin, named Bacthuricin F103,
from a Bacillus thuringiensis strain BUPM103. Bacthuricin F103 production began in the early exponential phase and reached a maximum in the middle of the
same phase. Two chromatographic methods based on high performance liquid chromatography and fast protein liquid chromatography
systems were used to purify Bacthuricin F103. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis revealed that this
bacteriocin had a molecular weight of approximately 11 kDa. It also showed a wide range of thermostability of up to 80 °C
for 60 min and a broad spectrum of antimicrobial activity over a pH range of 3.0–10.0. This bacteriocin was noted, and for
the first time, to exhibit potent antimicrobial activity against Agrobacterium subsp. strains, the major causal agents of crown gall disease in tomato and vineyard crops, and against several challenging
organisms in food, such as Listeria monocytogenes and Bacillus cereus. Complete killing with immediate impact on cells was observed within a short period of time. The sequence obtained for Bacthuricin
F103 by direct N-terminal sequencing shared considerable homology with hemolysin. Bacthuricin F103 was noted to act through
the depletion of intracellular ions, which suggest that the cell membrane was a possible target to Bacthuricin F103. 相似文献
32.
Algebraic decay and variable speeds in wavefront solutions of a scalar reaction-diffusion equation 总被引:1,自引:0,他引:1
Wavefront solutions of scalar reaction-diffusion equations havebeen intensively studied for many years. There are two basiccases, typified by quadratic and cubic kinetics. An intermediatecase is considered in this paper, namely, ul = uxx + u2(1 u). It is shown that there is a unique travelling-wave solution,with a speed 1/2, for which the decay to zero ahead of the waveis exponential with x. Moreover, numerical evidence is presentedwhich suggests that initial conditions with such exponentialdecay evolve to this travelling-wave solution, independentlyof the half-life of the initial decay. It is then shown thatfor all speeds greater than 1/2 there is also a travelling-wavesolution, but that these faster waves decay to zero algebraically,in proportion to 1/x. The numerical evidence suggests that initialconditions with such a decay rate evolve to one of these fasterwaves; the particular speed depends in a simple way on the detailsof the initial condition. Finally, initial conditions decayingalgebraically for a power law other than 1/x are considered.It is shown numerically that such initial conditions evolveeither to an algebraically decaying travelling wave, or in somecases to a wavefront whose shape and speed vary as a functionof time. This variation is monotonic and can be quite pronounced,and the speed is a function of u as well as of time. Using asimple linearization argument, an approximate formula is derivedfor the wave speed which compares extremely well with the numericalresults. Finally, the extension of the results to the more generalcase of ul = uxx + um(1 u), with m > 1, is discussed. 相似文献
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34.
Vito VeceKhadija Ben Hadj Hassen Sylvain Antoniotti Elisabet Duñach 《Tetrahedron letters》2012,53(38):5102-5105
We described herein a Sn(NTf2)4-catalysed cyclisation of gem-(dialkoxymethyl)-1,6-dienes and derivatives where cyclohexane or tetrahydrofuran rings are formed following either a 6-enexo-endo-trig process or a 5-exo-trig process, respectively, depending on substitution patterns. The latter process features an unusual dealkylative ether cyclisation, triggered by the strong Lewis acid character of the tin(IV) triflimidate catalyst. 相似文献
35.
超高效液相色谱-串联质谱联用法同步检测抗生素生产废水中螺旋霉素与新螺旋霉素残留 总被引:1,自引:0,他引:1
采用超高效液相色谱-串联质谱法同步测定了抗生素生产废水中残留的螺旋霉素(SPM-Ⅰ)和新螺旋霉素(NSPM-Ⅰ)。考察了萃取溶剂种类、水样pH值、萃取次数、水样与萃取溶剂的体积比等因素对目标物回收率的影响。以ACQUITY UPLC BEH C18(100 mm×2.1 mm i.d.,1.7 μm)为分析柱,0.1%甲酸水溶液和乙腈为流动相梯度淋洗,流速0.2 mL/min,电喷雾正离子多重反应监测模式检测。标准曲线在0.02~1.00 mg/L范围内线性关系良好,r2均大于0.999。方法回收率为70% ~ 88%,相对标准偏差小于10%,检出限(S/N=3)分别为0.03 μg/L(SPM-Ⅰ)和0.06 μg/L(NSPM-Ⅰ)。该方法应用于无锡市某制药厂抗生素生产废水中SPM-Ⅰ和NSPM-Ⅰ的检测,检出质量浓度分别为(115.6±2.7) mg/L和(5.3±0.4) mg/L。 相似文献
36.
In this paper, we introduce and study the Sobolev spaces of exponential type associated with the Weinstein operator, via some elements of harmonic analysis related to this operator. In particular, some properties, including completeness and imbedding theorem, are proved. Finally, using the theory of reproducing kernels, some applications are given for these spaces. 相似文献
37.
38.
In 2011, Berinde and Borcut [6] introduced the notion of tripled fixed point in partially ordered metric spaces. In our paper, we give some new tripled fixed point theorems by using a generalization of Meir-Keeler contraction. 相似文献
39.
Luo Shaohua Li Shaobo Yang Guanci Ouakad Hassen M. Karami Farzad 《Nonlinear dynamics》2020,101(1):293-309
Nonlinear Dynamics - This paper mainly investigates dynamical analysis and anti-oscillation-based adaptive control issues of the fractional-order (FO) arch microelectromechanical system (MEMS) with... 相似文献
40.