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排序方式: 共有175条查询结果,搜索用时 15 毫秒
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The metabolic pathway collection from EMP: the enzymes and metabolic pathways database. 总被引:4,自引:1,他引:3 下载免费PDF全文
E Selkov S Basmanova T Gaasterland I Goryanin Y Gretchkin N Maltsev V Nenashev R Overbeek E Panyushkina L Pronevitch E Selkov Jr I Yunus 《Nucleic acids research》1996,24(1):26-28
The Enzymes and Metabolic Pathways database (EMP) is an encoding of the contents of over 10 000 original publications on the topics of enzymology and metabolism. This large body of information has been transformed into a queryable database. An extraction of over 1800 pictorial representations of metabolic pathways from this collection is freely available on the World Wide Web. We believe that this collection will play an important role in the interpretation of genetic sequence data, as well as offering a meaningful framework for the integration of many other forms of biological data. 相似文献
3.
水分胁迫对大果沙枣光合特性及生物量分配的影响 总被引:16,自引:0,他引:16
选取大果沙枣1年生幼苗,盆栽于相对含水量分别为70%~75%(CK)、50%~55%(T1)、35%~40%(T2)和15%~20%(T3)的土壤中培养25 d,研究大果沙枣在水分胁迫下的光合特性变化和生物产量积累及其分配规律。结果显示:水分胁迫抑制了大果沙枣的光合作用,与对照相比,T2和T3处理导致净光合速率、叶片蒸腾速率和水分利用效率显著降低,气孔阻力、胞间二氧化碳浓度和叶绿素含量升高,而且光合午休明显,非气孔因素是干旱时大果沙枣净光合速率下降的主要原因;水分胁迫下,大果沙枣的生长受到抑制,地上部分和地下部分的干生物量积累同时降低,但地下干生物量降低的程度低于地上部分;干旱处理中,T3处理显著抑制大果沙枣的生长,但仍保持一定的生物量增加。结果表明:大果沙枣具有一定的自我调节与保护能力,在水分胁迫下大果沙枣趋于将更多的资源分配给根系,以提高根冠比而适应干旱的环境。 相似文献
4.
In this study, the findings of three water mite species of the family Hygrobatidae collected from different streams in Turkey were evaluated. Hygrobates (s. str.) anatolicus Esen & Pešić, sp. n. is described as new for science. Hygrobates (Rivobates) diversiporus Sokolow, 1927 and Atractides (s. str.) nikooae Pešić, 2004, which were illustrated and thoroughly discussed, are new records for the Turkish fauna. 相似文献
5.
A new water mite species Sperchon (Hispidosperchon) serapae n. sp. is described. The material was collected from a slow-flowing stream during field study on the water mite fauna of the Lakes region in southwestern Turkey. An updated list of hitherto known species of Sperchon Kramer from Turkey, including nomenclatural changes and numerous new locality records to the species, is also given. 相似文献
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Meryem Beklioglu Ayse Gul Gozen Feriha Yıldırım Pelin Zorlu Sertac Onde 《Hydrobiologia》2008,614(1):321-327
Vertical migration of Daphnia represents the best-studied predator-avoidance behaviour known; yet the mechanisms underlying the choice to migrate require
further investigation to understand the role of environmental context. To investigate the optimal habitat choice of Daphnia under fish predation pressure, first, we selected the individuals exhibiting strong migration behaviour. The animals collected
from the hypolimnion during the daytime were significantly larger, being more conspicuous, and in turn performed stronger
diel vertical migration (DVM) when exposed to fish cue. We called them strong migrants. Second, we provided the strong migrant
D. pulex with food at high and intermediate (1 and 0.4 mg C l−1, respectively) levels, which were well above the incipient limiting level and of high quality. They traded the benefits of
staying in the warm water layer and moved down to the cold water in response to fish cue indicating fish predation. The availability
of food allowed the animals to stay in the cold hypolimnion. However, at the low food level (0.1 mg C l−1), which is an additional constraint on fitness, Daphnia moved away from the cold hypolimnion. Poor food condition resulted in strong migrant Daphnia to cease migration and remain in the upper warmer water layer. Although temperature is known to be a more important cost
factor of DVM than food, our results clearly show that this is only true as long as food is available. It becomes clear that
food availability is controlling the direction of vertical positioning when daphnids experience a dilemma between optimising
temperature and food condition while being exposed to fish cue. Then they overlook the predation risk. Thus, the optimal habitat
choice of Daphnia appears to be a function of several variables including temperature, food levels and fish predation.
Handling editor: S. I. Dodson 相似文献
8.
Duygu İnci Özgür Vatan Yunus Zorlu Nilüfer Çinkılıç 《Journal of biomolecular structure & dynamics》2013,31(15):3878-3901
New binary copper(II) complexes – [Cu(4-mphen)2(NO3)]NO3·H2O (1), [Cu(5-mphen)2 (NO3)]NO3·H2O (2), the known complex [Cu(dmphen)2(NO3)]NO3 (3) and [Cu(tmphen)2 (NO3)]NO3·H2O (4) - (4-mphen: 4-methyl-1,10-phenanthroline, 5-mphen: 5-methyl-1,10-phenanthroline, dmphen: 4,7-dimethyl-1,10-phenanthroline, tmphen: 3,4,7,8-tetramethyl-1,10-phenanthroline), have been synthesized and characterized by CHN analysis, ESI-MS, FTIR and single-crystal X-ray diffraction techniques. Interaction of these complexes with calf thymus DNA (CT-DNA) has been investigated by absorption spectral titration, ethidium bromide (EB) and Hoechst 33,258 displacement assay and thermal denaturation measurement. These complexes cleaved pUC19 plasmid DNA in the absence and presence of an external agent. Notably, in the presence of H2O2 as an activator, the cleavage abilities of these complexes are obviously enhanced at low concentration. Addition of hydroxyl radical scavengers like DMSO shows significant inhibition of the DNA cleavage activity of these complexes. BSA quenching mechanism was investigated with regard to the type of quenching, binding constant, number of binding locations and the thermodynamic parameters. The experimental results suggested that the probable quenching mechanism was an unusual static process and hydrophobic forces play a dominant role. The CT-DNA and BSA binding efficiencies of these complexes follow the order: 4 > 3 > 1 > 2. Furthermore, in vitro cytotoxicities of these complexes on tumor cells lines (Caco-2, MCF-7 and A549) and healthy cell line (BEAS-2B) showed that these complexes exhibited anticancer activity with low IC50 values. The effect of hydrophobicity of the methyl-substituted phenanthrolines on DNA and protein binding activities of these complexes is discussed. 相似文献
9.
Effects of different physical pretreatments on water hyacinth for dilute acid hydrolysis process (121 ± 3 °C, 5% H2SO4, 60 min) were comparatively investigated. Untreated sample had produced 24.69 mg sugar/g dry matter. Steaming (121 ± 3 °C) and boiling (100 ± 3 °C) for 30 min had provided 35.9% and 52.4% higher sugar yield than untreated sample, respectively. The highest sugar yield (132.96 mg sugar/g dry matter) in ultrasonication was obtained at 20 min irradiation using 100% power. The highest sugar production (155.13 mg sugar/g dry matter) was obtained from pulverized samples. Hydrolysis time was reduced when using samples pretreated by drying, mechanical comminution and ultrasonication. In most methods, prolonging the pretreatment period was ineffective and led to sugar degradations. Morphology inspection and thermal analysis had provided evidences of structure disruption that led to higher sugar recovery in hydrolysis process. 相似文献
10.
Bekhit AA El-Sayed OA Aboul-Enein HY Siddiqui YM Al-Ahdal MN 《Journal of enzyme inhibition and medicinal chemistry》2004,19(1):33-38
Synthesis of a novel series of structurally related pyrazoloquinoline nucleosides is described. All the newly synthesized compounds were examined for their in vitro antiviral activity against herpes simplex type-1 as shown by two different bioassays, namely; crystal violet staining or the MTS tetrazolium dye measurement. The acute toxicity (LD50) values of the biologically active compounds were determined. 相似文献