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排序方式: 共有66条查询结果,搜索用时 15 毫秒
1.
Semenov V. M. Lebedeva T. N. Pautova N. B. Khromychkina D. P. Kovalev I. V. Kovaleva N. O. 《Eurasian Soil Science》2020,53(4):454-466
Eurasian Soil Science - The distribution of total organic matter (Corg), particulate organic matter (CPOM), and potentially mineralizable organic matter (C0) in mega- (10–5 and 5–2 mm),... 相似文献
2.
Nikitin D. A. Ivanova E. A. Zhelezova A. D. Semenov M. V. Gadzhiumarov R. G. Tkhakakhova A. K. Chernov T. I. Ksenofontova N. A. Kutovaya O. V. 《Eurasian Soil Science》2020,53(12):1782-1793
Eurasian Soil Science - Quantitative characteristics of microbial communities in southern agrochernozems of the Stavropol region managed with the use of no-till technology and moldboard plowing... 相似文献
3.
The origin of jets emitted from black holes is not well understood; however, there are two possible energy sources: the accretion disk or the rotating black hole. Magnetohydrodynamic simulations show a well-defined jet that extracts energy from a black hole. If plasma near the black hole is threaded by large-scale magnetic flux, it will rotate with respect to asymptotic infinity, creating large magnetic stresses. These stresses are released as a relativistic jet at the expense of black hole rotational energy. The physics of the jet initiation in the simulations is described by the theory of black hole gravitohydromagnetics. 相似文献
4.
V. P. Rybalko V. V. Semenov O. L. Tret’yakova L. V. Kononova O. V. Pluzhnikova 《Russian Agricultural Sciences》2011,37(1):76-78
A combined index of reproductive qualities (CIRQ) is used for evaluating the reproductive productivity of sows of different genotypes, the index V 100 * for evaluating young replacement stock, and the index for evaluating fattening qualities. The best crossing variants are revealed as a result of using the index evaluations: Large White of the Grigoropolis-1 type (LW GT) × Early Maturing Meat of the steppe type (EM-1 ST) × Landrace (L); EM-1 ST × (EM-1 ST × L); and L × (EM-1 ST × L). 相似文献
5.
P.D. Jamieson I.R. Brooking M.A. Semenov G.S. McMaster J.W. White J.R. Porter 《Field Crops Research》2007
Simulation of the timing of anthesis in wheat crops is achieved using two very different approaches. The older of these simulates progress to flowering by calculating the duration of phases between significant events on the shoot apex. The alternative method tracks development through leaf appearance, using the prediction of final mainstem leaf number to control the duration of the phase from emergence to flowering. Although these methods appear to differ substantially, we show in this paper that the number of leaves on the mainstem when the stage of terminal spikelet occurs is extremely tightly coupled to final mainstem leaf number. We conclude that accurate prediction of the terminal spikelet stage or similar prediction of mainstem leaf number amount to the same thing, so reconciling the methods. 相似文献
6.
A. M. Semenov I. A. Bubnov V. M. Semenov E. V. Semenova V. V. Zelenev N. A. Semenova 《Eurasian Soil Science》2013,46(8):869-884
The daily dynamics of the number of copiotrophic and oligotrophic bacteria (in colony-forming units) and CO2 emissions from cultivated soils after short- and long-term disturbances were studied for 25–27 days in a microfield experiment. The relationship of the wavelike fluctuations of the bacterial number and CO2 emission with the succession of the soil microbial community was determined by the polymerase chain reaction method—denaturing gradient gel electrophoresis (PCR-DGGE). Short-term disturbances involved the application of organic or mineral fertilizers, pesticides, and plant residues to the soils of different plots. The long-term effect was a result of using biological and intensive farming systems for three years. The short-term disturbances resulted in increased peaks of the bacterial number, the significance of which was confirmed by harmonics analysis. The daily dynamics of the structure of the soil microbial community, which was studied for 27 days by the DGGE method, also had an oscillatory pattern. Statistical processing of the data (principal components analysis, harmonics and cross-correlation analyses) has revealed significant fluctuations in the structure of microbial communities coinciding with those of the bacterial populations. The structure of the microbial community changed within each peak of the dynamics of the bacterial number (but not from peak to peak), pointing to the cyclical character of the short-term succession. The long-term effects resulted in a less intense response of the microbiota—a lower rate of CO2 emission from the soil cultivated according to the organic farming system. 相似文献
7.
In the future, UK summers are likely to be warmer and drier. Modelling differential water redistribution and uptake, we assessed the impact of future drier climates on sugar beet yields. Weather was generated for 1961–1990 (BASE) and predictions based on low‐ and high‐emission scenarios (LO, HI) described in the most recent global climate simulations by the Hadley Centre, UK. Distributions and variability of relative soil moisture deficit (rSMD) and yield gap (drought‐related yield loss, YGdr = 1?actual yield/potential yield), and sugar yield were calculated for different time‐lines using regional weather, soil texture and management inputs. The rSMD is estimated to exceed the senescence threshold with a probability of 75% (2050sLO) to 95% (2080sHI) compared with 65% (BASE). The potential yield loss, YGdr, is likely to increase from 17% (BASE) to 22% (2050sLO) to 35% (2080sHI). However, increasing potential growth rates (CO2 × temperature) cause average sugar yields to rise by between 1.4 and 2 t ha?1 (2050sLO and 2050sHI respectively). Yield variation (CV%) may increase from 15–18% (BASE) to 18–23% (2050s) and 19–25% (2080s). Differences are small between regions but large within regions because of soil variability. In future, sugar yields on sands (8 t ha?1) are likely to increase by little (0.5–1.5 t ha?1), but on loams yields are likely to increase from 11 to 13 t ha?1 (2050sHI) and 15 t ha?1 (2080sHI). Earlier sowing and later harvest are potential tools to compensate for drought‐related losses on sandy soils. 相似文献
8.
Ariena H. C. van Bruggen Alexander M. Semenov Anne D. van Diepeningen Oscar J. de Vos Wim J. Blok 《European journal of plant pathology / European Foundation for Plant Pathology》2006,115(1):105-122
A healthy soil is often defined as a stable soil system with high levels of biological diversity and activity, internal nutrient
cycling, and resilience to disturbance. This implies that microbial fluctuations after a disturbance would dampen more quickly
in a healthy than in a chronically damaged and biologically impoverished soil. Soil could be disturbed by various processes,
for example addition of a nutrient source, tillage, or drying-rewetting. As a result of any disturbance, the numbers of heterotrophic
bacteria and of individual species start to oscillate, both in time and space. The oscillations appear as moving waves along
the path of a moving nutrient source such as a root tip. The phase and period for different trophic groups and species of
bacteria may be shifted indicating that succession occurs. DGGE, Biolog and FAME analysis of subsequent populations in oscillation
have confirmed that there is a cyclic succession in microbial communities. Microbial diversity oscillates in opposite direction
from oscillations in microbial populations. In a healthy soil, the amplitudes of these oscillations will be small, but the
background levels of microbial diversity and activity are high, so that soil-borne diseases will face more competitors and
antagonists. However, soil-borne pathogens and antagonists alike will fluctuate in time and space as a result of growing plant
roots and other disturbances, and the periods and phases of the oscillations may vary. As a consequence, biological control
by members of a single trophic group or species may never be complete, as pathogens will encounter varying populations of
the biocontrol agent on the root surface. A mixture of different trophic groups may provide more complete biological control
because peaks of different trophic groups occur at subsequent locations along a root. Alternatively, regular addition of soil
organic matter may increase background levels of microbial activity, increase nutrient cycling, lower the concentrations of
easily available nutrient sources, increase microbial diversity, and enhance natural disease suppression. 相似文献
9.
10.
Eurasian Soil Science - The taxonomic composition, abundance, and diversity of bacterial and fungal communities in the rhizosphere loci and bulk mass of the gray forest soil (Eutric Retisol... 相似文献