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91.
92.
Yang B Chen GY Song XP Yang LQ Han CR Wu XY Li XM Zou BY 《Bioorganic & medicinal chemistry letters》2012,22(11):3828-3830
Two new daphnane diterpenoids (1 and 2), together with four known analogues (3-6) were isolated from Trigonostemon xyphophylloides. Their structures were elucidated by spectroscopic analysis. Compounds 1 and 2 were evaluated for in vitro cytotoxic activities against the SPCA-1 (human lung cancer) and BEL-7402 (human hepatocellular carcinoma) cancer cell lines. Trigoxyphin I (2) showed modest cytotoxicity against two tumor cell lines. 相似文献
93.
Simulation of sequential batch reactor (SBR) operation for simultaneous removal of nitrogen and phosphorus 总被引:3,自引:0,他引:3
Ho Nam Chang Ra Kyung Moon Byung Geon Park Seong-Jin Lim Dong Won Choi Woo Gi Lee Seok Lyong Song Yong Hee Ahn 《Bioprocess and biosystems engineering》2000,23(5):513-521
Modeling of the operation of sequential batch reactor (SBR) was performed to find out optimum design parameters for simultaneous removal of nitrogen and phosphorus in a small-scale wastewater treatment plant. The models were set up with material balances on SBR operation and Monod kinetics. The model parameters were obtained to best fit the experimental results in a small scale SBR. The models were useful in optimizing hydraulic retention time (HRT) and successfully simulated operations of SBR in a larger scale. Especially the model predicted well the reactions occurring in the filling period as well as the effect of dilution, and evaluated the performance of SBR process under diverse operating conditions. 相似文献
94.
Mg2+ can potentially influence bacterial adhesion directly through effects on electrostatic interactions and indirectly by affecting physiology-dependent attachment processes. However, the effects of Mg2+ on biofilm structure are largely unknown. In this study, Pseudomonas fluorescens was used to investigate the influence of Mg2+ concentration (0, 0.1 and 1.0 mM MgCl2) on biofilm growth. Planktonic and attached cells were enumerated (based on DAPI staining) while biofilm structures were examined via confocal laser scanning microscopy and three-dimensional structures were reconstructed. Mg2+ concentration had no influence on growth of planktonic cells but, during biofilm formation, Mg2+ increased the abundance of attached cells. For attached cells, the influence of Mg2+ concentration changed over time, suggesting that the role of Mg2+ in bacterial attachment is complex and dynamic. Biofilm structures were heterogeneous and surface colonization and depth increased with increasing Mg2+ concentrations. Overall, for P. fluorescens, Mg2+ increased initial attachment and altered subsequent biofilm formation and structure. 相似文献
95.
The objective of this study was to analyze the clinical manifestation, imaging characteristics, genotype, and the relationship
between the three aforementioned parameters in two pedigrees suffering from spinocerebellar ataxia. To evaluate the clinical
manifestation of the two pedigrees and to compare the characteristics, we performed the MRI analysis of some patients from
both pedigrees, while 2 ml of the peripheral blood sample was collected for gene analysis. The gene analysis data showed that
pedigree 1 was certified spinocerebellar ataxia type-2 (SCA2); the CAG repeats in the proband, proband’s mother, and proband’s
brother were 44, 36, and 38, respectively. The MRI revealed brainstem cerebellar atrophy and “cross sign” and “ordinate sign”
of pons. Pedigree 2 was certified SCA1; the CAG repeats of the proband, proband’s aunt, and proband’s asymptomatic cousin
were 60, 51, and 52, respectively. The MRI revealed cerebellar atrophy in these individuals. We, therefore, concluded that
it was difficult to diagnose the SCA subset solely through the clinical manifestation. The imaging characteristics analysis
and final diagnosis depended basically on gene analysis data. 相似文献
96.
97.
重金属镉、锌在菹草叶细胞中的超微定位观察 总被引:19,自引:0,他引:19
水环境污染中十分突出的是重金属的污染 ,主要来源为流入物、渗漏和大气沉降 (Larcher ,1995 )。由于重金属污染物不但不能被微生物所分解 ,而且能在生物体内富集 ,并通过水生食物链的生物放大作用而对高营养级的生物甚至人类造成危害 ,因此日益引起人们的特别关注。许多研究从超微结构损伤和生理生化的角度研究了重金属对植物的毒害机制。施国新等 (2 0 0 0 )观察了重金属汞、镉污染对水生植物黑藻叶细胞的超微结构损伤。彭鸣等 (1991)研究了重金属镉、铅诱导的玉米超微结构的变化。李荣春 (2 0 0 0 )研究了Cd、Pb及其复合污染… 相似文献
98.
不同预处理对大麦花药3种内源激素含量和过氧化物酶活性的影响 总被引:5,自引:0,他引:5
研究了大麦(Hordeum vulgare L.)花药-花粉培养中不同预处理对花药内源激素(ABA,IAA,IPA)含量和过氧化物酶活性的影响。结果表明:1. 经甘露醇预处理不同天数,同一种基因型的3种内源激素的变化和不同基因型的同一种内源激素的变化规律十分相似,均是在预处理初期含量急剧增加,最高值在0.5或1 d 处。以后开始逐渐下降;最后,保持在一定的水平上。2. 在甘露醇预处理过程中,两种基因型花药过氧化物酶活性的变化规律也十分相似。在预处理前期(从开始到第3天)活性呈直线上升,第3天达到最大值。从第3天到第5天活性减弱。最后,活性又开始增强。3. 在低温预处理过程的初期(2~5 d) 两种基因型花药过氧化物酶活性都出现第一个小峰。在第14天(“Harrington”)或第21天(“Igri”)又出现第二个峰值,但后者较高。在预处理的后期(从第28天到第35天)两种基因型花药过氧化物酶的活性又呈现上升的趋势。同甘露醇预处理后期变化一致 相似文献
99.
Ning-Ning Song Yan Zheng Shi-Jin E Duo-Chuan Li 《Journal of microbiology (Seoul, Korea)》2009,47(1):123-130
A superoxide dismutase (SOD) gene of Thermoascus aurantiacus var. levisporus, a thermophilic fungus, was cloned, sequenced, and expressed in Pichia pastoris and its gene product was characterized. The coding sequence predicted a 231 residues protein with a unique 35 amino acids
extension at the N-terminus indicating a mitochondrial-targeting sequence. The content of Mn was 2.46 μg/mg of protein and
Fe was not detected in the purified enzyme. The enzyme was found to be inhibited by NaN3, but not by KCN or H2O2. These results suggested that the SOD in Thermoascus aurantiacus var. levisporus was the manganese superoxide dismutase type. In comparison with other MnSODs, all manganese-binding sites were also conserved
in the sequence (H88, H136, D222, H226). The molecular mass of a single band of the enzyme was estimated to be 21.7 kDa. The
protein was expressed in tetramer form with molecular weight of 68.0 kDa. The activity of purified protein was 2,324 U/mg.
The optimum temperature of the enzyme was 55°C and it exhibited maximal activity at pH 7.5. The enzyme was thermostable at
50 and 60°C and the half-life at 80°C was approximately 40 min. 相似文献
100.
Effects of resuspension and eutrophication level on summer phytoplankton dynamics in two hypertrophic areas of Lake Taihu,China 总被引:1,自引:0,他引:1
The composition of summer phytoplankton communities in two highly eutrophic areas of Lake Taihu, a large, shallow water body
in China (area 2,338 km2; mean depth 2.0 m), was studied in relation to selected environmental variables. Both areas have multiple uses, including
drinking water supply, fisheries, and recreation. The first area, Meiliang Bay, is much closer to central lake and subjected
to wind-driven sediment resuspension, while the second, at Wuli Lake, is less affected by wave action but is considered more
nutrient-rich due to its proximity to human inhabitation. By comparing two lake areas, we attempt to advance the understanding
and management of different regions of shallow lakes, mainly differing in resuspension levels and eutrophication levels. A
comparison of these two lake areas indicated a higher standing crop of phytoplankton in Wuli Lake than in Meiliang Bay. Canonic
Correspondence Analysis indicated that nutrient status and sediment resuspension were the principal factors influencing phytoplankton
composition in both areas. The dominant algal group in Meiliang Bay comprised immobile R-type strategists (Reynolds in Growth and reproductive strategies of freshwater phytoplankton, 1988), including filamentous diatoms and green algae (Aulacoseira granulate and Planctonema lauterbornii), and recruitment-beneficial RS-type strategists, mainly the colonial cyanobacteria (Microcystis spp.). The community of Wuli Lake was dominated by S-strategists, principally motile flagellates (Cryptomonas spp.) and C-strategists including small nonmotile centric diatoms and chlorococcal green algae. 相似文献