排序方式： 共有22条查询结果，搜索用时 15 毫秒
1.
Gogotsi Y 《Science (New York, N.Y.)》2010,330(6009):1332-1333
2.
Remco Ursem Yury Tikunov Arnaud Bovy Ralph van Berloo Fred van Eeuwijk 《Euphytica》2008,161(1-2):181-193
Network analysis of correlations between abundances of metabolites across tomato genotypes can help in unraveling the biological
basis of organoleptic variation in tomato. We illustrate how to construct and interpret simple correlations networks using
metabolic data collected on a diverse set of tomato genotypes. Various types of correlations are calculated and displayed
in the form of networks. Interpretations on the basis of network analyses are compared to interpretations following principal
components analysis. 相似文献
3.
Brain-derived neurotrophic factor (BDNF) and other neurotrophins are critically involved in long-term potentiation (LTP). Previous reports point to a presynaptic site of neurotrophin action. By imaging dentate granule cells in mouse hippocampal slices, we identified BDNF-evoked Ca2+ transients in dendrites and spines, but not at presynaptic sites. Pairing a weak burst of synaptic stimulation with a brief dendritic BDNF application caused an immediate and robust induction of LTP. LTP induction required activation of postsynaptic Ca2+ channels and N-methyl-d-aspartate receptors and was prevented by the blockage of postsynaptic Ca2+ transients. Thus, our results suggest that BDNF-mediated LTP is induced postsynaptically. Our finding that dendritic spines are the exclusive synaptic sites for rapid BDNF-evoked Ca2+ signaling supports this conclusion. 相似文献
4.
典型黑土区村级尺度侵蚀沟演变 总被引：5，自引：0，他引：5
侵蚀沟的演变是东北水土流失过程的重要方面.利用1968和2009年亚米级遥感影像,获取典型黑土区村级尺度的侵蚀沟分布、耕地垄向和土地利用数据,基于1∶1万地形图获取等高线、坡度、坡长和垄向坡度数据,在地理信息系统和遥感技术的支持下,分析典型黑土区41 a村级尺度侵蚀沟的动态变化及其影响因素.结果表明:1)41 a间,典型黑土区侵蚀沟密度有明显增加的趋势,基于分辨率为亚米级遥感影像解译的侵蚀沟密度较以往研究结果大幅增加;2)自然坡度0.25°～1.5°范围内为该区域侵蚀沟密度变化最大的区域,8°以上区域由于实施退耕还林措施,侵蚀沟密度降低;3)300～500 m坡长区域侵蚀沟密度出现极值;4)由于实施改垄措施,41 a后垄向坡度在0～0.25°范围内耕地面积增加,大于0.25°范围内耕地面积均减少. 相似文献
5.
Marine J. Paupière Pauline van Haperen Ivo Rieu Richard G. F. Visser Yury M. Tikunov Arnaud G. Bovy 《Euphytica》2017,213(6):130
Among the abiotic stresses affecting plant reproduction, high temperature is one of the most prominent ones because it directly affects fruit set. So far, little attention has been paid to the investigation of the variation in high temperature tolerance among wild tomato (Solanum lycopersicum) germplasm. The objective of this study was to determine the tolerance of 17 different cultivated and wild tomato accessions to high temperature, using a pollen viability screening approach. Each of the 17 genotypes of tomato was analysed for their pollen quality under a 32 °C (day)/26 °C (night) regime. The total number of pollen per flower and the fraction of viable pollen were recorded. The number of pollen per flower varied between 35,547 and 109,490 whereas the fraction of viable pollen varied between 0.03 and 0.71. No correlation was found between these two traits. However, the combination of these traits could provide the best reproductive capability under high temperature. In this study, thermo-tolerant (LA2854, LA1478 and LA0417) as well as thermo-sensitive (LA1719, LA1580, and SWEET4) genotypes have been identified. Those genotypes can be used as novel genetic resources to get more insight into pollen thermo-tolerance mechanisms and be included in breeding programs. 相似文献
6.
Patricia Menéndez Paul Eilers Yury Tikunov Arnaud Bovy Fred van Eeuwijk 《Euphytica》2012,183(3):379-387
The search for models which link tomato taste attributes to their metabolic profiling, is a main challenge within the breeding
programs that aim to enhance tomato flavor. In this paper, we compared such models calculated by the traditional statistical
approach, stepwise regression, with models obtained by the new generation of regression techniques, known as penalized regression
or regularization methods. In addition, for penalized regression, different scenarios and various model selection criteria
were discussed to conclude that classical crossvalidation, selects models with many superfluous variables whereas model selection
criteria such as Bayesian information criterion, seem to be more suitable, when the goal is to find parsimonious models, to
explain tomato taste attributes based on metabolic information. An exhaustive comparison of the discussed methodology was
done for six sensory traits, showing that the most important covariates were identified by the stepwise regression as well
as by some of the penalized regression methods, despite the general disagreement on the size of the regression coefficients
between them. In particular, for stepwise regression the coefficients are inflated due to their high variance which is not
the case with penalized regression, showing that this new methodology, can be an alternative to obtain more accurate models. 相似文献
7.
Nikolai A. Provorov Yury D. Soskov Ludmila A. Lutova Olga A. Sokolova Serdar S. Bairamov 《Euphytica》1996,88(2):129-138
Summary As a result of the analysis of 31 fenugreek (Trigonella foenum-graecum L.) genotypes we demonstrated that subsp. indica surpass significantly subsp. foenum-graecum in fresh weight, seed yield, nodulation ability, resistance to coot rot and the duration of the interstage and growing periods. There was no difference between the subspecies for leafiness and biochemical composition of seeds (concentrations of diosgenin and steroid glucosides, nitrogen, fat, inhibitors of tripsin and hemotripsin). The most promising genotypes (as compared with the standard cv. Nakhichevanskaya Shambala) yield 1650–1938 g/m2 of fresh weight, 98.2–116.1 g/m2 of seeds and accumulate 1.45–1.64% of diosgenin in seeds. High positive correlations (r=+0.53 ... +0.84; Po<0.01) were found between fresh weight, seed yield, plant leafiness and height. Inoculation of the cv. Nakhichevanskaya Shambala with Rhizobium meliloti strains 851 and 852 increased its fresh weight by 94.5% and 93.6% and seed yield by 83.1% and 60.5%, respectively. Significant correlations of the nodule number with the fresh weight and seed yield (r=+0.70 and +0.77; Po<0.01) allow us to assume that selection for increased symbiotic activity may be useful for improving the fenugreek productivity. The intersubspecies hybrids (four genotypes) surpass the subsp. indica (six genotypes) for the sizes of calli formed in presence of 2.4-D and kinetin. The sizes of calli formed by ten analysed genotypes in presence of BAP and kinetin (or 2.4-D) were negatively correlated with the nodule number (or fresh weight). 相似文献
8.
Fedoreyev SA Bulgakov VP Grishchenko OV Veselova MV Krivoschekova OE Kulesh NI Denisenko VA Tchernoded GK Zhuravlev YN 《Journal of agricultural and food chemistry》2008,56(16):7023-7031
Isoflavonoids, an interesting and restricted group of secondary metabolites of legumes, exhibit estrogenic, antiangiogenic, and anticancer activities and are now popular as dietary supplements. Plant cell cultures that possess an increased ability to synthesize these metabolites were examined. During the investigation, cell cultures of the Far Eastern relict tree Maackia amurensis (Leguminosae) were established. A selection of seed-derived cell aggregates yielded the callus line designated A-18. This culture produces 20 isoflavonoids, namely, the isoflavones genistein, daidzein, formononetin, calycosin, derrone, and pseudobaptigenin and their glycosylated conjugates genistin, 6'-O-malonylgenistin, ononin, 6'-O-malonylononin, daidzin, 3'-methoxydaidzin, 4'-O-beta-D-glucopyranosyldaidzin, 4'-O-beta-D-glucopyranosylgenistin, and 7-O-beta-D-glucopyranosylcalycosin; the pterocarpans maackiain and medicarpin and their glycosylated conjugates 6'-O-malonyl-3-O-beta-D-glucopyranosylmaackiain and 6'-O-malonyl-3-O-beta-D-glucopyranosylmedicarpin; and the new pterocarpan glucoside 6'-O-malonyl-3-O-beta-D-glucopyranosyl-6,6a-dehydromaackiain. These isoflavonoids, possessing a hepatoprotective activity, were stably produced by the A-18 calli for prolonged periods of observation. 相似文献
9.
Georgiana Daian Alexander Taube Amikam Birnboim Mihai Daian Yury Shramkov 《Wood Science and Technology》2006,40(3):237-246
A method for calculating the complex dielectric permittivity of an anisotropic wood structure at microwave frequencies is
presented. A numerical model for describing the 3D wood structure containing fibers, rays, vessels and cracks with changeable
dimensions and material composition is built. This model is introduced into an efficient solver that calculates the effective
dielectric constant of any 3D structure of dielectric materials. Using our numerical model we succeeded in theoretically reproducing
the results of recent measurements of the dielectric permittivity of wood, in various directions and various moisture contents.
The qualitative agreement is realistic, reproducing all the trends of the changes in ɛ as the direction of the electric field
and the moisture content are varied. The quantitative agreement is practical and reliable for engineering calculations with
an average deviation of ±10% in ɛ′ and ±5% in ɛ′′. As microwave processing of wood involves internal temperatures as high
as 150°C and pressures of up to 5 atm, the dielectric properties of wood were also calculated with the same numerical model
by simulating high internal temperature and pressure. A comparison between the calculated and measured values shows once again
how accurate the model reproduces the empirical study. 相似文献
10.
Yury N. Samsonov Valery I. Makarov Konstantin P. Koutsenogii 《Pest management science》1998,52(3):292-302
Contamination of the atmosphere by pesticides is an inevitable consequence of their application for plant protection, and a substantial part of pesticide pollutants exists as airborne particles. Evaporation of particulate matter is often the main pathway that provides the removal of intraparticle pesticide, and, thus, the detoxication of aerosol pollutants occurs. On the other hand, evaporation causes entry of pesticide vapour into the air, and may result in pesticide contamination of the atmosphere. The known models of particle evaporation cannot be directly used for realistic multi-ingredient pesticide formulations because the data on the physico-chemical properties of particle constituents are usually absent or unavailable. A simplified model is derived which describes the evaporation of the pesticide out of both an individual particle and a polydisperse aerosol mixture, taking into account the pesticide vapour pressure-temperature dependence, initial content of pesticide in particles, aerosol sizes, and degree of particle polydispersity, etc. The temperature dependencies of evaporation rates for both the polydisperse aerosol mixtures, and the particles of diameter dm≈2 μm, and, then, of an arbitrary diameter were determined for malathion, parathion-methyl, phosalone, propiconazole, and ethaphos formultions. The unknown vapour concentration or pressure-temperature dependencies were evaluated for some pesticides, and the evaporation life-times of particles were estimated under ambient conditions. ©1998 SCI 相似文献