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1.
Water level regulation causes large-scale ecological changes in the littoral areas of lakes in northern Finland. If the summertime water level is raised, intensive erosion processes begin, causing a sudden decline in shore vegetation. The need for shore protection is obvious in areas of high recreational value. At lake Ontojärvi, planting experiments with littoral helophytes and bushes were carried out during the years 1990–92. All the experiments were carried out in the eroded sandy areas, which were partly protected by mechanical barriers. Several plant species were planted on the shore which had been treated with different peat mixtures, etc. The frequencies of the different species were followed monthly. After the first summer, the average survival rates were about 45 % due to the drying of seedlings. A rapid decrease in the survival rates took place during the high water level period in 1991 at which point only 20% of the planted individuals were alive. The best results were obtained for the helophyte Carex rostrata Stokes, of which 30% had survived erosion. Tall willows (Salix phylicifolia L.) were also erosion-resistant with a survival rate of 80%. 相似文献
2.
J. Hallborn N. Meinander B. Hahn-Hëgerdal M. -F. Gorwa M. Pentillä S. Keränen 《Applied microbiology and biotechnology》1994,42(2-3):326-333
Xylitol formation by a recombinantSaccharomyces cerevisiae strain containing theXYL1 gene fromPichia stipitis CBS 6054 was investigated under three sets of conditions: (a) with glucose, ethanol, acetate, or glycerol as cosubstrates, (b) with different oxygenation levels, and (c) with different ratios of xylose to cosubstrate. With both glucose and ethanol the conversion yields were close to 1 g xylitol/g consumed xylose. Decreased aeration increased the xylitol yield on the basis of consumed cosubstrate, while the rate of xylitol formation decreased. The xylitol yield based on consumed cosubstrate also increased with increased-xylose:cosubstrate ratios. The transformant utilized the cosubstrate more efficiently than did a reference strain in terms of utilization rate and growth rate, implying that the regeneration of NAD(P)+ during xylitol formation by the transformant balanced the intracellular redox potential. 相似文献
3.
抗人铁蛋白单抗6D6和A-hF-C与肝型铁蛋白和心型铁蛋白的反应性有所不同。6D6对两种铁蛋白的反应性相似;而A-hF-C单抗与肝型铁蛋白的反应性较强。我们将6D6和A-hF-C分别制成了亲和凝胶,用来纯化人肝脏和心脏粗抽提物中的铁蛋白。此法具有操作简便,产率和产品纯度高等优点。 相似文献
4.
5.
Antti Keränen 《Chemistry and physics of lipids》1976,17(1):14-21
The fatty acid and long-chain base composition of five major gangliosides from human stomach and small and large intestine mucosa were analyzed with gas chromatography. All the gangliosides greatly resembled each other in the fatty acid pattern. The main fatty acids were C16:0, C18:0 and C24:0. No hydroxy fatty acids could be detected. In all the gangliosides 4-sphingenine was the predominant long-chain base (70–75%). About 15% of the long-chain bases had 20 carbon atoms in their chain. No trihydroxy long-chain bases could be detected. 相似文献
6.
Charng-Cherng Chyau Yaw-Bee Ker Chi-Huang Chang Shiau-Huei Huang Hui-Er Wang Chiung-Chi Peng Robert Y. Peng 《PloS one》2014,9(1)
Schisandra chinensis (Turz Baill) (S. chinensis) (SC) fruit is a hepatoprotective herb containing many lignans and a large amount of polysaccharides. A novel polysaccharide (called SC-2) was isolated from SC of MW 841 kDa, which exhibited a protein-to-polysaccharide ratio of 0.4089, and showed a characteristic FTIR spectrum of a peptidoglycan. Powder X-ray diffraction revealed microcrystalline structures within SC-2. SC-2 contained 10 monosaccharides and 15 amino acids (essential amino acids of 78.12%w/w). In a HepG2 cell model, SC-2 was shown by MTT and TUNEL assay to be completely non-cytotoxic. A kinetic analysis and fluorescence-labeling technique revealed no intracellular disposition of SC-2. Combined treatment of lignans with SC-2 enhanced the intracellular transport of schisandrin B and deoxyschisandrin but decreased that of gomisin C, resulting in alteration of cell-killing bioactivity. The Second Law of Thermodynamics allows this type of unidirectional transport. Conclusively, SC-2 alters the transport and cell killing capability by a “Catcher-Pitcher Unidirectional Transport Mechanism”. 相似文献
7.
Yan-Hui Yu Li Zhang Deng-Shu Wu Zheng Zhang Fang-Fang Huang Jian Zhang Xiao-Ping Chen De-Sheng Liang Hui Zeng Fang-Ping Chen 《PloS one》2013,8(11)
Currently, there are difficulties associated with the culturing of pluripotent human embryonic stem cells (hESCs), and knowledge regarding their regulatory mechanisms is limited. MicroRNAs (miRNAs) regulate gene expression and have critical functions in stem cell self-renewal and differentiation. Moreover, fibroblast growth factor (FGF) and the insulin-like growth factor receptor (IGF-1R) are key activators of signaling in hESCs. Based on the identification of complementary binding sites in miR-223 and IGF-1R mRNA, it is proposed that miR-223 acts as a local regulator of IGF-1R. Therefore, levels of miR-223 were detected in differentiated versus undifferentiated hESCs. In addition, proliferation, apoptosis, and differentiation were assayed in these two hESC populations and were compared in the presence of exogenous miR-223 and miR-223 inhibitor. Inhibition of miR-223 was found to maintain the undifferentiated state of hESCs, while addition of miR-223 induced differentiation. Furthermore, these effects were found to be likely dependent on IGF-1R/Akt signaling. 相似文献
8.
裸花紫珠是海南一种道地药材,具有消炎止血的功效。裸花紫珠富含黄酮类和苯乙醇苷类化学成分,它们已经被证实是天然抗氧化剂的主要来源之一。为了考察裸花紫珠药材的抗氧化活性,该研究采用DPPH.自由基清除法测定裸花紫珠醇提物、4个不同极性部位(石油醚、乙酸乙酯、正丁醇、水)及其7个主要成分的抗氧化作用。结果表明:裸花紫珠醇提物、醇提物的水部位、正丁醇部位、乙酸乙酯部位和化合物木犀草素、木犀草苷、毛蕊花糖苷具有较强的抗氧化活性,而5-羟基-3,7,3′,4′-四甲氧基黄酮的抗氧化活性则较弱。该研究结果为裸花紫珠的保健功能开发提供了依据。 相似文献
9.
Jeroen C. Verheijen Ker Yu Lourdes Toral-Barza Irwin Hollander Arie Zask 《Bioorganic & medicinal chemistry letters》2010,20(1):375-379
2-Aryl-4-morpholinothieno[3,2-d]pyrimidines are known PI3K inhibitors. This class of compounds also potently inhibited the homologous enzyme mTOR. Replacement of the morpholine group in these compounds with an 8-oxa-3-azabicyclo[3.2.1]octane group led to mTOR inhibitors with selectivity over PI3K. Optimization of the 2-aryl substituent led to the discovery of 2-(4-ureidophenyl)-thienopyrimidines as highly potent (IC50 <1 nM) mTOR inhibitors with excellent selectivity (up to >1000-fold) over PI3K and good potency in a cellular proliferation assay (IC50 <50 nM). 相似文献
10.
Reaction of mono-, di-, and trisaccharide derivatives of methyl beta-D- and octyl beta-D-mannopyranosides bearing ester groups at isolated and non-isolated positions on the same molecule, under Zemplén conditions (catalytic amount of sodium methoxide in methanol) gave partially deacylated compounds, in which the O-acyl groups were retained at isolated sites. In the case of one disaccharide, all the benzoyl groups remained intact at the reducing end, while all the acetyl functions were removable from the nonreducing end. In another case, both isolated ester groups at positions 2 and 4 were retained at the reducing end. The isolated 2-O-acyl groups on methyl alpha-D-mannopyranoside compounds were more labile than on the corresponding beta-mannosides under the same conditions. The mechanism of the reaction may be different for ester groups at isolated or non-isolated positions. In the latter case, acyl migration may take place and carry acyl groups into a less hindered position. 相似文献