排序方式: 共有17条查询结果,搜索用时 15 毫秒
1.
The stable isotopic composition (delta(2)H and delta(18)O) of short-term (daily) precipitation collected from October 2002 to September 2003 at two stations in a coastal, karstic area in south-western Slovenia was investigated. In addition, monthly composite samples were collected and analysed for comparison with amount-weighted monthly means. The delta(2)H and delta(18)O values obtained show a wide range and reflect seasonal climatic variations. Deuterium excess and local meteoric water lines (LMWLs) were determined and cumulative frequency analysis and coincidence tests were performed. The statistical coincidence test showed that the LMWLs calculated from monthly data for Portoroz and Kozina are coincident, but the LMWLs calculated from daily precipitation events are not. This difference could be explained by the greater variance of the isotopic composition of daily precipitation in comparison to monthly composite samples and also to the influence of evaporation during events below<1 mm at Portoroz during the extremely dry and warm spring-summer season of 2003. Finally, synoptic maps and backward trajectories of a selected precipitation event showed that changes of isotopic composition are related to mixing of air masses originating from the continent and Mediterranean cyclogenesis. 相似文献
2.
- Download : Download high-res image (205KB)
- Download : Download full-size image
3.
Toll convexity is a variation of the so-called interval convexity. A tolled walk between two non-adjacent vertices and in a graph is a walk, in which is adjacent only to the second vertex of and is adjacent only to the second-to-last vertex of . A toll interval between is a set . A set is toll convex, if for all . A toll closure of a set is the union of toll intervals between all pairs of vertices from . The size of a smallest set whose toll closure is the whole vertex set is called a toll number of a graph , . The first part of the paper reinvestigates the characterization of convex sets in the Cartesian product of two graphs. It is proved that the toll number of the Cartesian product of two graphs equals 2. In the second part, the toll number of the lexicographic product of two graphs is studied. It is shown that if is not isomorphic to a complete graph, . We give some necessary and sufficient conditions for . Moreover, if has at least two extreme vertices, a complete characterization is given. Furthermore, graphs with are characterized. Finally, the formula for is given — it is described in terms of the so-called toll-dominating triples or, if is complete, toll-dominating pairs. 相似文献
4.
Identification of sources and production processes of bottled waters by stable hydrogen and oxygen isotope ratios 总被引:2,自引:0,他引:2
Bottled water is a food product that considerably depends on the environment from which it originates, not only at the place where it is produced, but predominantly on the conditions in the recharge area of the wells captured for bottling. According to their source and the bottling process, bottled waters can be divided into natural and artificially sparkling waters, still and flavoured waters. These waters originate from various parts of the hydrological cycle and their natural origin is reflected in their hydrogen and oxygen stable isotopic compositions (delta(2)H and delta(18)O). A total of 58 domestic and foreign brands and 16 replicates of bottled waters, randomly collected on the Slovene market in September 2004, were analysed for delta(2)H and delta(18)O. The isotopic composition varied between -83 per thousand and -46 per thousand with an average of -66 per thousand for hydrogen, and between -11.9 per thousand and -7.5 per thousand with an average of -9.6 per thousand for oxygen. This investigation helped (1) to determine and test the classification of bottled waters, (2) to determine the natural origin of bottled water, and (3) to indicate differences between the natural and production processes. The production process may influence the isotopic composition of flavoured waters and artificially sparkling waters. No such modification was observed for still and natural sparkling waters. The methods applied, together with hydrological knowledge, can be used for the authentication of bottled waters for regulatory and consumer control applications. 相似文献
5.
Polona Oblak 《Linear algebra and its applications》2008,428(7):1476-1491
In this paper we completely characterize all possible pairs of Jordan canonical forms for mutually annihilating nilpotent pairs, i.e. pairs (A,B) of nilpotent matrices such that AB=BA=0. 相似文献
6.
Polona Smrkolj Vekoslava Stibilj Ivan Kreft Emese Kapolna 《Analytical sciences》2005,21(12):1501-1504
Pumpkins were treated by spraying the leaves in the flowering period with a water solution containing 1.5 mg Se per liter in the form of Na2SeO4. The average total selenium content of seeds was found to be 0.19 microg g(-1) in nontreated pumpkins and 1.1 microg g(-1) in exposed ones. For speciation analysis, enzymatic hydrolysis with different amounts of Protease XIV was carried out. Under optimal conditions of enzymatic hydrolysis, 90% of the total selenium was found in soluble forms. Separation of species was performed using HPLC on anion and cation exchange columns and for detection UVHG-AFS was applied. In enzymatic hydrolysis extracts, the main fraction of selenium was bound as selenomethionine (SeMet), representing on average of 81 +/- 8% of the total Se content in the sample. 相似文献
7.
We calculate the diameters of commuting graphs of matrices over the binary Boolean semiring, the tropical semiring and an
arbitrary nonentire commutative semiring. We also find the lower bound for the diameter of the commuting graph of the semigroup
of matrices over an arbitrary commutative entire antinegative semiring. 相似文献
8.
Kokol Vanja Vivod Vera Peršin Zdenka Kamppuri Taina Dobnik-Dubrovski Polona 《Cellulose (London, England)》2021,28(10):6663-6678
Cellulose - Low moisture absorbency of hydrophobically coated flame-resistant (FR) fabrics do not correlate well with the thermophysiological comfort. In this frame, we were the first to study the... 相似文献
9.
Tišma M Znidaršič-Plazl P Vasić-Rački D Zelić B 《Applied biochemistry and biotechnology》2012,166(1):36-46
Laccases are very interesting biocatalysts for several industrial applications. Its production by different white-rot fungi
can be stimulated by a variety of inducing substrates, and the use of lignocellulosic wastes or industrial by-products is
one of the possible approaches to reduce production costs. In this work, various industrial wastes were tested for laccase
production by Trametes versicolor MZKI G-99. Solid waste from chemomechanical treatment facility of a paper manufacturing plant showed the highest potential
for laccase production. Enzyme production during submerged cultivation of T. versicolor on the chosen industrial waste has been further improved by medium optimization using genetic algorithm. Concentrations of
five components in the medium were optimized within 60 shake-flasks experiments, where the highest laccase activity of 2,378 U dm−3 was achieved. Waste from the paper industry containing microparticles of CaCO3 was found to stimulate the formation of freely dispersed mycelium and laccase production during submerged cultivation of
T. versicolor. It was proven to be a safe and inexpensive substrate for commercial production of laccase and might be more widely applicable
for metabolite production by filamentous fungi. 相似文献
10.
Baresić J Horvatincić N Krajcar Bronić I Obelić B Vreca P 《Isotopes in environmental and health studies》2006,42(3):239-249
Stable isotopic compositions (delta2H and delta18O) of daily precipitation collected in the period from October 2002 to March 2003 and monthly precipitation in the period from 2001 to 2003, as well as the corresponding meteorological data (temperature, amount of precipitation), all collected in Zagreb, Croatia, are presented. delta2H and delta18O values, both daily and monthly, show large variations due to large temperature variations and the different origin of the air masses. Variations are larger for daily samples than for composite monthly samples. Good correlation of delta18O with temperature is obtained for both types of samples. On the basis of the correlation between delta2H and delta18O, the local meteoric water line is close to the global meteoric water line. Deuterium excess of both daily and monthly precipitation indicates that in the Zagreb area, the influence of air masses from the Mediterranean area prevails in the autumn period. 相似文献