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We use tools of the equilibrium statistical mechanics of disordered systems to study analytically the statistical properties of an ecosystem composed of N species interacting via random mutual interactions, as well as via deterministic self-interactions of order p>/=2. We show that the main effect of increasing the order of the interactions among the species is to make the system less competitive, in the sense that the fraction of extinct species is greatly reduced. In addition, we find that for p>2 there is a threshold value which gives a lower bound to the concentration of the surviving species, preventing then the existence of rare species and, consequently, increasing the robustness of the ecosystem to external perturbations. 相似文献
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A. A. Druzhinin N. E. Kaurov S. A. Nemkov V. A. Ishutin 《Journal of Analytical Chemistry》2010,65(12):1242-1244
A chemiluminescence method was developed for determining o-chlorobenzylidenemalonic acid dinitrile (o-CBMA DN) in extracts. The method is based on chemiluminescence developed in a strong alkaline solution upon the interaction between
3-aminophthalic hydrazide (luminol) with the superoxide radical formed in the reaction of atmospheric oxygen activated by
hemin with the products of the alkaline hydrolysis of o-chlorobenzylidenemalonic acid dinitrile and with the products of their condensation with p-nitrobenzaldehyde. The luminescence intensity of luminol was proportional to the concentration of o-CBMA DN in the range 1 × 10−6−1 × 10−1 mg/mL. The determination limit for o-CBMA DN was (1 ± 0.3) × 10−6 mg/mL (p = 95%, n = 5, RSD = 29%) at 293 K. 相似文献
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V. N. Kaurov 《Russian Physics Journal》1994,37(7):599-605
A semiclassical method of calculating the differential scattering cross section of electrons of a weak-current beam by a potential center is proposed, which takes into account the effect of the space charge of the beam on the scattering.Mozhaiskii Order of the Red Banner Military Engineering Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 3–10, July, 1994. 相似文献
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S. V. Burov O. A. Kaurov V. F. Martynov M. P. Smirnova 《Chemistry of Natural Compounds》1980,16(5):518-524
In order to study the influence of substituents of the aromatic ring of D-phenyl-alanine on the inhibiting capacity of luliberian
analogs, we have synthesized two new analogs:
and
luliberin. The synthesis was performed by the fragmentary condensation method using 2+(3+5) and 2+(5+3) schemes. A new and
convenient method of obtaining the amide of the C-terminal tetrapeptide of the luliberin sequence has been developed. In the
condensation of the fragments, both the azide and the carbodimide method of synthesis with the addition of l-hydroxybenzotriazole
were used. The guanidino group of arginine was protected by nitration, while the hydroxy groups of serine and of tyrosine
were not protected. The complete elimination of the protective groups from the decapeptides was performed by catalytic hydrogenation
over Pd on carbon and by anhydrous HF with the addition of anisole at 0°C. The protected octa- and decapeptides were purified
by gel filtration on Sephadex LH-20 in ethanol or by preparative thin-layer chromatography on silica gel plates. The final
peptides were purified by ion-ex-exchange chromatography on Sephadex CM-25.
A. A. Zhdanov Leningrad State University. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 706–714, September–October,
1980. 相似文献
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Allison M Fox Mike Anderson Corinne Reid Tim Smith Dorothy VM Bishop 《BMC neuroscience》2010,11(1):1-15
Background
We examined development of auditory temporal integration and inhibition by assessing electrophysiological responses to tone pairs separated by interstimulus intervals (ISIs) of 25, 50, 100, 200, 400, and 800 ms in 28 children aged 7 to 9 years, and 15 adults.Results
In adults a distinct neural response was elicited to tones presented at ISIs of 25 ms or longer, whereas in children this was only seen in response to tones presented at ISIs above 100 ms. In adults, late N1 amplitude was larger for the second tone of the tone pair when separated by ISIs as short as 100 ms, consistent with the perceptual integration of successive stimuli within the temporal window of integration. In contrast, children showed enhanced negativity only when tone pairs were separated by ISIs of 200 ms. In children, the amplitude of the P1 component was attenuated at ISIs below 200 ms, consistent with a refractory process.Conclusions
These results indicate that adults integrate sequential auditory information into smaller temporal segments than children. These results suggest that there are marked maturational changes from childhood to adulthood in the perceptual processes underpinning the grouping of incoming auditory sensory information, and that electrophysiological measures provide a sensitive, non-invasive method allowing further examination of these changes. 相似文献6.
D. O. Vetkin E. T. Gainullina S. A. Eremin N. E. Kaurov S. B. Ryzhikov V. F. Taranchenko V. I. Tsekhmister 《Journal of Analytical Chemistry》2003,58(11):1091-1094
Enzyme assay is proposed for improving the selectivity of the determination of an organophosphorus (carbamate) insecticide in the presence of a heavy-metal salt in a sample (exemplified by a model system containing proserine and mercuric bromide). The method involves the use of a substrate–indicator system based on acylthiocholine and Ellman's reagent (or its derivative). 相似文献
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The mutual drag in strongly interacting two-component superfluids in optical lattices is discussed. Two competing drag mechanisms are the vacancy-assisted motion and proximity to a quasimolecular state. In a case of strong drag, the lowest energy topological excitation (vortex or persistent current) can consist of several circulation quanta. In the SQUID-type geometry, the circulation can become fractional. We present both the mean field and Monte Carlo results. The drag effects in optical lattices are drastically different from the Galilean-invariant Andreev-Bashkin effect in liquid helium. 相似文献
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Summary 1. The separation of pentafluorophenylalanine into optical antipodes has been effected.2. Two new analogs of oxytocin — [2-L-pentafluorophenylalanine]oxytocin and [2-D-pentafluorophenylalanine]oxytocin — have been synthesized and their uterotonic activities have been studied.3. It has been shown that donor — acceptor interaction plays a fundamental role in the stimulation of the biological effect.A. A. Zhdanov Leningrad State University. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 392–398, May–June, 1977. 相似文献
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