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61.
0IntroductionRareearthsarenowappliedwidelyinChina,whichcanimprovecropsyieldsandthetheirqualit-ies犤1犦.Thebeneficialeffectsmaybeduetothestimu-latoryeffectsoftheseelementsonthenutrientuptakebyplantsorontheincreasingofchlorophyllsynthesisintheplants犤2犦.Whilealotofresearcheshavebeendoneontheimprovednutritionofcropsafterapplica-tionofrareearths,muchlessattentionhasbeenpaidtothedeteriorationofsoilqualityduetotheapplicationofrareearthsforyears犤3犦.Scientistshavediscoveredthataccumula… 相似文献
62.
Cheanyeh Cheng 《中国化学会会志》1998,45(5):679-688
The activity of cellulase has traditionally been described by pH and temperature; however, the buffering medium is also an important factor, Taking plain water as a reference medium, three kinds of buffer including KH2PO4/K5HPO4, citric acid/sodium citrate, and acetic acid/sodium acetate were adopted to survey their effects on the activity of cellulase. Chromatographic assays indicated that xylose, glucose, and cellobiose were the major products and that minor products such as cellotriose and cellotetraose were present in some cases. The activities of cellulase based on glucose production showed that the phosphate buffer acted as a deactivator for cellulase and each of the two organic acid buffers acted as activators for cellulase. The concentration of activation buffer should be high to reach a high cellulase activity; however, this effect would be compensated for by the product inhibition of cellulase. The highest activity obtained was 4.16 ± 0.08 (× 10?3) IU mg?1 for the citric acid/sodium citrate buffer under pH 4.80, 40 °C and an agitation speed of 150 rpm. 相似文献
63.
玉米芯水溶性多糖的分离纯化和抗凝血活性研究 总被引:2,自引:0,他引:2
从玉米芯中提取到水提水溶性粗多糖,通过乙醇分级、冻融、凝胶过滤层析,生物测定导向等手段,分离到一种能延长体外凝血时间,而且具有外源抗凝血功能的多糖CCⅢ.CCⅢ对活化部分凝血酶原时间(APTT)无显著影响,但可显著延长体外抗凝血时间(PT).将CCⅢ纯化,经糖组成分析、甲基化、高碘酸氧化、Smith降解和GC-MS分析,确定该多糖结构为:β-(1→4)Glc,(1→3)Xyl构成主链,Glc在6-O处有分枝.平均每10个糖残基有1个分枝,支链由β-(1→3)Xyl,(1→3)Glc构成. 相似文献
64.
CHEN Shuixia LIU Jinrong ZHANG Xiaoping ZENG Hanmin Materials Science Institute Zhongshan University Guangzhou Department of Environmental Science Engineering South China University of Technology Guangzhou P. R. China 《Chinese Journal of Reactive Polymers》2002,(2)
1. INTRODUCTION Microbial pollution will bring about various problems in industry and other vital fields, such as causing decomposing of materials, harming people抯 health. In order to reduce these problems, new antibacterial materials have been demanded. Recently, much attention has been paid to inorganic materials including zinc oxide [1~4]. These inorganic antibacterial materials are now substituting for organic materials to avoid releasing noxious organic molecules harmful to humans;… 相似文献
65.
Barros N. Feijóo S. Simoni A. Critter S. A. M. Airoldi C. 《Journal of Thermal Analysis and Calorimetry》2000,63(2):577-588
The microcalorimetric method was used to calculate the metabolic enthalpy change per mol of glucose degraded by soil microorganisms,
ΔH
met. This parameter has been calculated by microcalorimetry for many organic, inorganic and biochemical reactions, but there
is only some information about its quantification for microbial growth reactions in soils. Values of ΔH
met were calculated for different soil samples collected in Galicia (Spain) and Campinas (Săo Paolo, Brazil). Exponential microbial
growth was stimulated in all soil samples by the addition of glucose and power-time curves were recorded. Results showed changes
in the values of ΔH
met calculated for all the soil samples, suggesting a dependence of this value with the microbial growth rate constant, with
the percentage of growth, with the initial number of microorganisms of soil samples, with the quantity of glucose added and
with the strain of bacteria growing in soil.
The interpretation of variations of ΔH
met provides important qualitative and quantitative information. It reports data that allow to interpret from a qualitative point
of view, the increase in biomass as a consequence of the degradation of the organic matter in soil, to understand changes
in the percentages of soil organic matter and to know if the microbial population growing in differential soil samples is
homogeneous. Therefore, to report that value would be very important in ecological studies, but beforehand, it is necessary
to solve some problems that can appear in the experiments done to make the quantification
.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
66.
Edith Gößnitzer Ales Krbavcic Winfried Wendelin Marija Krbavcic 《Monatshefte für Chemie / Chemical Monthly》2002,133(9):1177-1185
Summary. Novel N-(3-oxobutyl)-hydroxy- and acetoxypyrido[2,3-d]pyridazinones were synthesized and tested in vivo for their sedative and anticonvulsant activity. The Michael-type reaction of quinolinic acid hydrazide and methyl vinyl ketone afforded a mixture of two isomers, 5-hydroxy-N
7-(3-oxobutyl)-pyrido[2,3-d]pyridazin-8(7H)-one and 8-hydroxy-N
6-(3-oxobutyl)-pyrido[2,3,-d]pyridazin-5-(6H)-one, in a ratio of 2:1 which were separated by crystallization. Subsequent acetylation of both isomers yielded the corresponding
5- and 8-acetoxy compounds. The structures of the compounds were proven and completely assigned on the basis of 1H, 13C, 15N NMR, and 1D NOE difference spectra as well as 2D C,H-correlation experiments. Preliminary pharmacological tests showed low
acute toxicity with a LD
50 > 1000 mg/kg in the mouse and sedative activity for the title compounds. 5-Acetoxy-N
7- (3-oxobutyl)-pyrido[2,3-d]pyridazin-8(7H)-one displayed a borderline anticonvulsant activity in the metrazole test model.
Corresponding author. E-mail: edith.goessnitzer@uni-graz.at
Received March 20, 2002; accepted April 3, 2002 相似文献
67.
Ewald Haidl Daniel Krois Harald Lehner 《Monatshefte für Chemie / Chemical Monthly》1985,116(1):119-131
Biliverdins undergo appreciable self association in acidic solutions especially if solvents like benzene or chloroform are employed. The population of aggregates further depends on the concentration of both the acid and the solute. In chloroform and benzene solutions at high acidity a doubly protonated species is formed. This is concluded from a combinatory evaluation of the CD and electronic absorption spectra of chiral optically active biliverdins (1–6) in benzene, chloroform, and ethanol solutions containing trifluoroacetic acid or hydrochloric acid. The aggregates formed at medium acid concentrations exhibit largeCotton effects in the long-wavelength absorption bands and thus dominate the CD spectra. Similarly, agrregates are the main contributors to theCotton effects of achiral, protonated biliverdins in (S)-(–)-ethyl lactate (SICD) at usual concentrations. The consequence and relevance of these findings with regard to the recent literature is briefly discussed.Dedicated to Prof. Dr.Karl Schlögl on occasion of his 60th birthday. 相似文献
68.
本文综述了前列环素及其类似物的合成。类似物包括有7-羰基—、10,10-二氟—、5-氯—,4-羰基—、6,9-硫—、6,9-氮—,6 a-碳—前列环素以及苯前列环素等。前列环素及其类似物是一类具有抑制血小板聚集的生物活性化合物。 相似文献
69.
We optimized the hot water extraction of polysaccharides from the root of Henry wood betony (RHWPs) using a uniform test and explored their anti-tumor activities in vitro and in vivo. The optimal extraction conditions were as follows: 40 min extraction time, liquid/solid ratio 30 mL/g, 100 min soaking time, two extraction cycles, 100% ethanol concentration, and extraction temperature of 80 °C. The molecular weight distribution of RHWPs with MWs was 228,600 g/mol and 5001 g/mol. The IR spectrum further indicated that RHWPs are acidic polysaccharides containing pyranose and furan rings. The main monosaccharides found in RHWPs were mannose, ribose, l-rhamnose monohydrate, glucuronic acid, galacturonic acid, glucose, galactose, xylose, arabinose, and fucose. RHWPs inhibited the proliferation of S180 tumor cells and induced apoptosis in vitro. Oral administration of RHWPs to tumor-bearing mice significantly inhibited the growth of the S180 xenografts, accelerated apoptosis in tumor cells, and expanded the necrotic regions. Furthermore, RHWPs also markedly increased the levels of TNF-α, IFN-γ, and IL-2 in the sera of tumor-bearing mice, and activated immune cells such as lymphocytes, NK cells, and macrophages, thereby inducing tumor cell apoptosis. Taken together, RHWPs are a promising anti-tumor agent that ought to be explored further. 相似文献
70.
Zur Synthese von fungizid wirksamen Isocamphanderivaten: Synthesen in der Isocamphanreihe, 34. Mitt.
Gerhard Buchbauer Helmut Spreitzer Margarete Kneidinger 《Monatshefte für Chemie / Chemical Monthly》1990,121(6-7):549-554
Summary Some esters of isocamphenilanic acid (4) have been prepared and tested for their fungicidal and insecticidal activity. Esters of various acids with isocamphanyl ethylalcohol (5) have also been synthesized and included in the fungicidal/acaricidal/insecticidal screening programme. All esters bear a geminal dimethyl group at C-3 of the bicyclus which is important because of its shielding effect. 相似文献