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Analysis of Seed-specificity of Silencing fad_2 Gene Expression in Transgenic Rapeseed Line W-4(Brassica napus L.) 被引量:3
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作者 陈松 彭琦 +5 位作者 周晓婴 高建芹 张维 张洁夫 浦惠明 戚存扣 《Agricultural Science & Technology》 CAS 2014年第8期1308-1311,1316,共5页
This study was to investigate the efficiency and specificity of RNAi silencing on the expression of endogenous fad2 gene in transgenic line W-4. [Method] The relative expression of fad2 gene in seeds at different deve... This study was to investigate the efficiency and specificity of RNAi silencing on the expression of endogenous fad2 gene in transgenic line W-4. [Method] The relative expression of fad2 gene in seeds at different developmental stages of 7th, 14th, 21st and 28th day after flowering (DAF) as wel as the root, stem, leaf at winter seedling stages of both the transgenic line W-4 and non-transgenic control Westar by real-time fluorescence quantitative PCR. [Results] The results showed the relative expression of fad2 gene was gradual y increasing with the days after flowering in the seeds of the control Westar, while it was found decreasing significantly since the 21st DAF in the seeds of the line W-4. The decline was up to 60% in comparison with the control Westar. However, no significant difference in the relative expression of fad2 gene in other organs like root, stem and leaf was observed between transgenic line W-4 and non-transgenic control Westar. Fatty acid composition analysis showed the oleic acid desaturation parameter(ODP) in seeds of the line W-4 was 0.07 in average, decreased by nearly 75% than control Westar which was 0.24 in average, while no significant difference in the seedling root, stem and leaf was measured between transgenic rapeseed and control. [Conclusion] The results above validated that RNA interference in transgenic rapeseed W-4 is at a seed-specific manner, not interfering with fad2 gene expression in organs such as the root, stem and leaf. The study also found that the period of fad2 gene expres-sion decline was wel coincided with the expression of napin gene, both appeared at the 21st DAF, indicating that the expression of dsRNA of fad2 gene is precisely control ed by the napin promoter. 展开更多
关键词 Transgenic rapeseed Real-time fluorescence quantitative PCR fad2gene Specific expression
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Selection of Reference Genes in Transcription Analysis of Gene Expression of the Mandarin Fish, Siniperca chuasti 被引量:17
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作者 周瑞雪 蒙涛 +6 位作者 孟海波 陈敦学 宾石玉 成嘉 符贵红 褚武英 张建社 《Zoological Research》 CAS CSCD 北大核心 2010年第2期141-146,共6页
At present, transcription analysis of gene expression commonly uses housekeeping genes as control for normalization. In this study, the expression levels of three housekeeping genes including GAPDH, β-actin, and 18S ... At present, transcription analysis of gene expression commonly uses housekeeping genes as control for normalization. In this study, the expression levels of three housekeeping genes including GAPDH, β-actin, and 18S rRNA in six tissues and five developmental stages of the Mandarin fish Siniperca chuatsi were assayed with quantitative real-time PCR (qPCR). Differences in expression levels were analyzed using geNorm program. The results demonstrate that β-actin is the most stable gene at developmental stages and GAPDH is the most stable in different tissues. While 18S rRNA expression during development is differentially regulated, which indicates it is suitable as an internal control for gene expression normalization at the developmental level. Overall, the data suggest that the two most stable housekeeping genes are enough to accurately calibrate gene expression in S. chuatsi. The significance of this study provided convincing references and methodology for housekeeping gene selection and normalization in gene expression analysis with regular PCR or qPCR. 展开更多
关键词 Reference genes geNorm program Gene expression Real-time PCR
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Temporal-spatial Changes in Inner Mongolian Grassland Degradation during Past Three Decades 被引量:10
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作者 张清雨 吴绍洪 +1 位作者 赵东升 戴尔阜 《Agricultural Science & Technology》 CAS 2013年第4期676-683,共8页
[Objective] This study aimed to analyze the temporal-spatial variation of Inner Mongolian grassland degradation during past three decades. [Method] The dis- tribution characteristics of grassland were described by lan... [Objective] This study aimed to analyze the temporal-spatial variation of Inner Mongolian grassland degradation during past three decades. [Method] The dis- tribution characteristics of grassland were described by land use types supervised classification with TM/ETM. Then, temporal-spatial changes of grassland coverage were quantified by the mean of maximum vegetation coverage in last 30 years. Lastly, the grassland degradation reasons were explored through statistic analysis between the grassland coverage and precipitation, temperature and grazing intensity. [Result] The grassland degradation index of Inner Mongolia was increased from 1.38 to 1.68, and the smallest was 1.28 in 2005s. Grassland degradation and improve- ment were concurrent after 1980s, but grassland degradation was the major change trend for Inner Mongolia grassland. The area of grassland degradation was enlarged from 18.08×10^4 km2 in 1980s to 22.47×10^4 km2 in 2010s on the whole and distribu- tion range was shifted from central-eastern to west in Inner Mongolia that mainly distributed on Hulun Buir and Xilin Gol grassland in 1980s and Ordos and Alax grassland in 2010s. The grassland area of degradation had a rising trend form 1980s to 1995s, then reduced to 10.8x104 km2 in 2005s, and decreased in 2010s, which mainly speared in the west of Xilin Gol grassland. [Conclusion] Inner Mongo-lian grassland degradation were become more seriously in last 30 years because that temperature, precipitation and graze intensities change, which not performance on decreasing coverage but grassland areas. 展开更多
关键词 Grassland degradation Temporal-spatial change Influencing factor Inner Mongolia
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Overexpression of IGF2R and IGF1R mRNA in SCNT-produced Goats Survived to Adulthood 被引量:1
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作者 邢宝松 徐银学 +2 位作者 成勇 刘红林 杜淼 《Journal of Genetics and Genomics》 SCIE CAS CSCD 北大核心 2007年第8期709-719,共11页
The procedure of somatic cell nuclear transfer (SCNT) is likely to affect the expression level of growth-related genes especially imprinting genes. In this study, expressions of growth-related genes including three ... The procedure of somatic cell nuclear transfer (SCNT) is likely to affect the expression level of growth-related genes especially imprinting genes. In this study, expressions of growth-related genes including three imprinting genes (H19, IGF2, and IGF2R) and four non-imprinting genes (IGF1, IGFIR, GHR, and GHSR) in adult nuclear transferred (NT) goats were investigated by real-time PCR. The expressions of these genes in adult clones were found largely normal, but IGF2R and IGFIR were more highly expressed in cloned goats than in non-NT goats (P 〈 0.01). Analysis on mono-allelic expression pattern of imprinting genes indicated that mono-allelic expression patterns of H19 and IGF2 in cloned goats were similar to that in non-NT goats. In addition, the sequence of goat IGF2 gene and the putative amino acid sequence were obtained. The 986 nucleotide cDNA of goat IGF2 gene contained an open-reading frame of 540 nucleotides coding for 179 amino acids. Both cDNA sequence and amino acid sequence of IGF2 in goat showed their higher homology with that in sheep than in cattle; the partial cDNA fragments of H19, IGF2R, GHSR, IGFIR, and GHR in goat were also cloned and sequenced, which shared higher sequence identities with those in sheep than in cattle. 展开更多
关键词 GOAT nuclear transfer gene expression real-time PCR imprinting gene
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Temporal and Spatial Distribution Characteristics of Potential Evapotranspiration and Its Sensitivity to Meteorological Factors in Guizhou Province 被引量:2
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作者 于飞 谷晓平 熊华 《Agricultural Science & Technology》 CAS 2015年第12期2845-2848,共4页
[Objective] The study aims to discuss the changes of potential evapotran- spiration and its sensitivity to meteorological factors in Guizhou Province, so as to provide important references for assessment of water reso... [Objective] The study aims to discuss the changes of potential evapotran- spiration and its sensitivity to meteorological factors in Guizhou Province, so as to provide important references for assessment of water resources, research of agri- cultural water conservancy and climate change. [Method] Temporal and spatial dis- tribution characteristics of potential evapotranspiration in Guizhou Province from 1961 to 2010 were analyzed, and the sensitivity of potential evapotranspiration to meteo- rological factors in Guizhou Province was studied through correlation analysis. [Re- sult] On the whole, potential evapotranspiration in Guizhou Province was higher in the southwest and the west compared with the northeast and the east. In various seasons, it was the highest in summer, followed by spring and autumn, while it was the lowest in winter. In recent 40 years, annual potential evapotranspiration showed an obvious decreasing trend in most stations of Guizhou Province. The main meteo- rological factors influencing changes of potential evapotranspiration in Guizhou Province were sunshine duration, daily maximum temperature, and daily average relative humidity. [Conclusion] Daily average temperature was not the main meteoro- logical factor affecting changes of potential evapotranspiration in Guizhou Province, while sunshine duration, daily maximum temperature, and daily average relative hu- midity had important effects on potential evapotranspiration in Guizhou Province. 展开更多
关键词 Potential evapotranspiration Temporal-and spatial distribution Sensitivefactor GUIZHOU
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大鳍鳠IgL2型基因cDNA的克隆及表达分析 被引量:1
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作者 李春涛 蒋自立 +1 位作者 曾伯平 张其中 《淡水渔业》 CSCD 北大核心 2014年第1期20-25,58,共7页
应用RT和RACE-PCR方法获得大鳍鳠(Mystus macropterus Bleeker)免疫球蛋白轻链(IgL)2型基因cDNA序列,分析了该基因在组织中的表达。该基因cDNA全长为929 bp,包含5'非编码区43 bp,3'非编码区159 bp,开放阅读框720 bp,编码239个... 应用RT和RACE-PCR方法获得大鳍鳠(Mystus macropterus Bleeker)免疫球蛋白轻链(IgL)2型基因cDNA序列,分析了该基因在组织中的表达。该基因cDNA全长为929 bp,包含5'非编码区43 bp,3'非编码区159 bp,开放阅读框720 bp,编码239个氨基酸。编码的氨基酸序列分为可变区(VL)和恒定区(CL)。系统进化树分析显示,大鳍鳠IgL蛋白质序列与斑点叉尾IgL 2型(G型)合为一支,与其它硬骨鱼类IgL2型聚为一簇。组织分布研究表明,大鳍鳠IgL2基因表达量在脾脏最高,其次是鳃和头肾,这明显与大鳍鳠IgL3型基因表达方式不同。注射嗜水气单胞菌后,大鳍鳠IgL2基因转录表达量在脾脏、鳃和头肾都随时间发生变化。IgL2基因转录表达量在脾脏4 d就到达高峰,在鳃1 d就达到峰值。这些应答规律与IgL3基因差异显著,推测,IgL2的表达主要参与鳃、肠和皮肤主导的粘膜免疫。 展开更多
关键词 大鳍鳠( Mystus macropterus) 克隆 表达
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Development of Studies on RNA Interference 被引量:1
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作者 张俐 张雅琼 +5 位作者 佘丽娜 徐文婷 贾阳映 谢世清 孙文丽 梁泉 《Agricultural Science & Technology》 CAS 2012年第9期1838-1842,共5页
RNA interference (RNAi), caused by endogenous or exogenous double- stranded RNA (dsRNA) homologous with target genes, refers to gene silencing widely existing in animals and plants. It was first found in plants, a... RNA interference (RNAi), caused by endogenous or exogenous double- stranded RNA (dsRNA) homologous with target genes, refers to gene silencing widely existing in animals and plants. It was first found in plants, and now it has developed into a kind of biotechnology as well as an important approach in post- genome era. This paper is to summarize the achievements of studies on RNAi tech- nology in basic biology, medicine, pharmacy, botany and other fields. 展开更多
关键词 RNA interference Post-genome Functional genome
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“因为时间关系”语义隐含偏向研究 被引量:1
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作者 刘宗保 《新疆大学学报(哲学社会科学版)》 CSSCI 2019年第2期138-142,共5页
"因为时间关系"表达中有偏向消极的语义隐含,这可以通过将"因为时间关系"还原为"因为时间VP"后VP的语义偏向,以及将"因为时间VP"转换为"因为时间关系"的可接受度得到证明。这一表达... "因为时间关系"表达中有偏向消极的语义隐含,这可以通过将"因为时间关系"还原为"因为时间VP"后VP的语义偏向,以及将"因为时间VP"转换为"因为时间关系"的可接受度得到证明。这一表达使用的语用动因是信息推理的可及性及"原因"信息的凸显程度,其隐含偏向的形成是"偏向常态"原则与"时间"语义偏移的语用机制合力的结果。 展开更多
关键词 因为时间关系 语义隐含偏向 “偏向常态”原则 语义偏移
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Determining the Copy Number of Exogenous Gene in Transgenic Plant by SYBR Green Real-time Quantitative PCR
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作者 裘劼人 许颖 喻富根 《Agricultural Science & Technology》 CAS 2011年第6期829-831,835,共4页
[Objective] To explore the feasibility of using SYBR Green real-time quantitative PCR technique to estimate the copy numbers of exogenous gene in a transgenic plant.[Methods] Using SYBR Green real-time quantitative PC... [Objective] To explore the feasibility of using SYBR Green real-time quantitative PCR technique to estimate the copy numbers of exogenous gene in a transgenic plant.[Methods] Using SYBR Green real-time quantitative PCR technique,we have determined the copy numbers of the exogenous CYCD3;1 in transgenic Arabidopsis by comparing an endogenous single copy reference gene with CYCD3;1 copy numbers in transgenic plant,meanwhile comparing CYCD3;1 copy numbers between wild plant and transgenic plant.[Results]The exogenous CYCD3;1 copy numbers calculated by this method is identical with results of traditional Southern blot analysis which is highly accurate.[Conclusion]This method is simple,effective and safe for estimating transgene copy numbers. 展开更多
关键词 Transgenic Arabidopsis SYBR Green real-time quantitative PCR Gene copy number
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A Method for Detecting Adhesive Related-Factors of Streptococcus suis Serotype 2 by Real-time PCR 被引量:1
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作者 汪伟 何孔旺 +9 位作者 倪艳秀 周俊明 张雪寒 俞正玉 吕立新 茅爱华 温立斌 王小敏 李彬 郭容莉 《Agricultural Science & Technology》 CAS 2013年第10期1378-1382,共5页
[Objective] This study aimed to establish a method for quantitative detection of mRNA transcriptional level of SS2 adhesive related-factors of Streptococcus suis serotype 2 (SS2) by fluorescent quantitative PCR. []V... [Objective] This study aimed to establish a method for quantitative detection of mRNA transcriptional level of SS2 adhesive related-factors of Streptococcus suis serotype 2 (SS2) by fluorescent quantitative PCR. []Vlethod] The gene fragments en- coding SS2 adhesive related-factors MRP, FBPS and CPS2J and a housekeeping gene aroA were amplified by reverse transcription PCR from the total RNA of SS2, cloned, and sequenced. The recombinant plasmids containing the target genes were constructed, and used as templates in Real-time PCR. [Result] Dynamic curves, stan- dard curves and melting curves of the adhesive related-factors and aroA were ob- tained by the optimized Real-time PCR system. The standard curves showed a good linear relationship between template copy number and circulation number, and the correlation coefficients (FF) of the standard curves were over 0.995. Also, these as- says were highly specific a^d there was single specific melting peak for every gene. Moreover, the assays were highly sensitive and had a detection limit of 1.0×102 copies in 1 μl of initial templates. Finally, it was highly repeatable and had a coeffi- cient of variation less than 2% for intra-assay. [Conclusion] This study will provide a way to reveal the adhesion mechanism of SS2 to different host cells at molecular level. 展开更多
关键词 Streptococcus suis serotype 2 Adhesive related-factors (adhesins) Real- time PCR
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Spatial-Temporal Distribution Characteristics and Limiting Factors of Medium-low Yield Farmland in Tianjin
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作者 潘洁 吕雄杰 +1 位作者 肖辉 陆文龙 《Agricultural Science & Technology》 CAS 2015年第3期578-582,共5页
[Objective] This paper aimed to understand the area change and distribu- tion of medium-low yield farmland, and offered basis to the improvement of mediumlow farmland and its increase of grain production in Tianjin. [... [Objective] This paper aimed to understand the area change and distribu- tion of medium-low yield farmland, and offered basis to the improvement of mediumlow farmland and its increase of grain production in Tianjin. [Method] Based on the statistical date of Tianjin and its relevant counties and districts, the yield standard was set up to classify high-yield, medium-yield and low-yield farmland in Tianjin. The author analyzed area change of medium-low yield farmland in six agricultural counties and districts (including Jixian County, Wuqing District, Baodi District, Ninghe County, Jinghai County and Dagang district of Binghai New Area) from 1980 to 2010. [Result] The results showed that the average yield of grain rose from 2 445 kg/hm^2 in 1980 to 5 130 kg/hm^2 in 2010, increasing 109.82%. The area of mediumlow yield farmland was reduced from 291 250.13 hm^2 in 1985 to 76 489.87 hm^2 in 2010, coming down 74%. In Tianjin, the area of medium-low yield farmland of 2010 accounted for 19% of the total farmland, of which the ratios of medium-low yield farmland of Jinghai County, Jixian County, Dagang district of Binghai New Area, Wuqing District, Baodi District and Ninghe County were 43.12%, 18.59%, 17.23%, 14.01%, 7.05% and 0, respectively. Low soil nutrient content, drought and water shortage, as well as soil salinization were the main yield limiting factors to mediumlow yield farmland in Tianjin in 2010. [Conclusion] The countermeasures to improve the medium-low yield farmland were proposed, involving enhancing the investment of the government, strengthening the construction of water conservancy infrastructure, further improving the soil fertility, as well as saline and alkaline land, optimizing the farming system and planting drought and salt tolerance crops, etc. 展开更多
关键词 Medium-low yield farmland Spatial-temporal distribution Limiting factors TIANJIN
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Real-time Quantitative PCR Analysis of Vascular Endothelial Growth Factor Receptor-2(VEGFR-2) Expression at Zebrafish Different Developmental Stages 被引量:2
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作者 孙桂金 潘杰 +2 位作者 刘可春 王雪 王思锋 《Agricultural Science & Technology》 CAS 2010年第4期118-120,共3页
[Objective]To investigate the expression of zebrafish vascular endothelial growth factor-2(VEGFR-2) at different developmental stages.[Method]Total RNAs were extracted from 12,24,48,72 and 96 hpf stage zebrafish emb... [Objective]To investigate the expression of zebrafish vascular endothelial growth factor-2(VEGFR-2) at different developmental stages.[Method]Total RNAs were extracted from 12,24,48,72 and 96 hpf stage zebrafish embryos and larvae.Real-time quantitative RT-PCR was performed to examine the expression of VEGFR-2.The data were analyzed by 2^-△△Ct method.[Result]The expression level of VEGFR-2 gene increased gradually from 12 to 72 hpf,and subsequently decreased at 96 hpf.The expression level was lowest at 12 hpf,highest at 72 hpf,and had significant differences when compared with that of other developmental stages.[Conclusion]The expression level of VEGFR-2 increases gradually before blood vessel maturation and decreases as blood vessels mature. 展开更多
关键词 ZEBRAFISH Real-time quantitative PCR VEGFR-2
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Adaptive Fuzzy Neural Control of Dynamic System
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作者 赵保军 韩月秋 毛二可 《Journal of Beijing Institute of Technology》 EI CAS 1999年第2期85-89,共5页
Aim To build an adaptive fuzzy neural controller and simulate it. Methods\ Fuzzy logic and back propagation(BP) algorithm are combined to utilize their advantages while avoiding the disadvantages. Results and Conclus... Aim To build an adaptive fuzzy neural controller and simulate it. Methods\ Fuzzy logic and back propagation(BP) algorithm are combined to utilize their advantages while avoiding the disadvantages. Results and Conclusion\ Simulation results of the third order plant with disturbances and dead times show the validity of the presented controller. The presented controller can control cases that preceding controllers were unable to control. 展开更多
关键词 error back propagation fuzzy logic learning rate nonlinear time varying parameter
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Analysis of Gene Expression of Seven Isoforms of ADP-glucose Pyrophosphorylase in Rice Endosperm under Different Temperature Conditions
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作者 袁定阳 孙志忠 +1 位作者 谭炎宁 段美娟 《Agricultural Science & Technology》 CAS 2012年第6期1226-1229,1233,共5页
[Objective] This study aimed to analyze the effects of temperature on the expression of AGPase isoform genes in rice endosperm during milk stage. [Method] Different temperature treatments (33 and 25 ℃ of daily mean ... [Objective] This study aimed to analyze the effects of temperature on the expression of AGPase isoform genes in rice endosperm during milk stage. [Method] Different temperature treatments (33 and 25 ℃ of daily mean temperature for high and normal temperature treatments, respectively) and the real-time fluorescence quantitative PCR ( FQPCR) were used to analyze the expression patterns of seven isoforms (AGPS1, AGPS2a, AGPS2b, AGPL1, AGPL2, AGPL3 and AGPL4) of ADPglucose pyrophosphorylase (AGPase) which was the key enzyme in starch synthesis and metabolism in rice endosperm of two rice varieties Teqing and Thai Fragrant Rice. [Result] The AGPase isoforms AGPS2b, AGPL2 and AGPL3 had much higher expression than the other four isoforms, thus they were thought to be the main expression patterns of AGPase in rice endosperm. The relative expressions of AGPL2 was the highest among all the isoforms. The relative expressions of AGPS2b, AGPL2 and AGPL3 were higher in the normal temperature treatment than in the high temperature treatment in both rice varieties. The relative expression of the three enzyme genes in milk stages in Teqing was higher than those in Thai Fragrant Rice under different temperature treatments. [Conclusion] This study provides a theoretical basis for further use of molecular biology techniques to cultivate stable high-quality rice varieties. 展开更多
关键词 RICE ADP-glucose pyrophosphorylase (AGPase) isoforms Gene expression characteristics Real-time fluorescence quantitative PCR (FQ-PCR)
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The optimal fractional Gabor transform based on the adaptive window function and its application 被引量:4
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作者 陈颖频 彭真明 +2 位作者 贺振华 田琳 张洞君 《Applied Geophysics》 SCIE CSCD 2013年第3期305-313,358,共10页
We designed the window function of the optimal Gabor transform based on the time-frequency rotation property of the fractional Fourier transform. Thus, we obtained the adaptive optimal Gabor transform in the fractiona... We designed the window function of the optimal Gabor transform based on the time-frequency rotation property of the fractional Fourier transform. Thus, we obtained the adaptive optimal Gabor transform in the fractional domain and improved the time-frequency concentration of the Gabor transform. The algorithm first searches for the optimal rotation factor, then performs the p-th FrFT of the signal and, finally, performs time and frequency analysis of the FrFT result. Finally, the algorithm rotates the plane in the fractional domain back to the normal time-frequency plane. This promotes the application of FrFT in the field of high-resolution reservoir prediction. Additionally, we proposed an adaptive search method for the optimal rotation factor using the Parseval principle in the fractional domain, which simplifies the algorithm. We carried out spectrum decomposition of the seismic signal, which showed that the instantaneous frequency slices obtained by the proposed algorithm are superior to the ones obtained by the traditional Gabor transform. The adaptive time frequency analysis is of great significance to seismic signal processing. 展开更多
关键词 FrFT generalized time bandwidth product optimal rotation factor search adaptive optimal Gabor transform spectral decomposition seismic signals
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Cloning and Expression of Pun1 Gene Controlling Pungency of Pepper (Capsicum spp.) 被引量:1
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作者 董雨薇 孙樱燃 +5 位作者 毕然 孙宁莉 阮文渊 李越 王晶莹 郭庆勋 《Agricultural Science & Technology》 CAS 2016年第11期2483-2488,共6页
[Objective] This study was conducted to investigate cloning and expression of Pun1 gene controlling pungency of pepper. [Method] With Capsicum annuum L as a material, the cDNA sequence of Capunl gene was obtained, wit... [Objective] This study was conducted to investigate cloning and expression of Pun1 gene controlling pungency of pepper. [Method] With Capsicum annuum L as a material, the cDNA sequence of Capunl gene was obtained, with a total length of 1 457 bp, coding 440 amino acids. [Result] Phylogenetic analysis showed that Capunl was closest to Pun1 of C. chinense, with a genetic distance of 0.019 3. Plant expression vector pCAM-Punl-GFP was constructed and transformed into to- bacco, and it was found that the protein coded by fusion gene Punl::GFP was lo- cated on cell membrane. Prokaryotic expression vectors were constructed, and by SDS-PAGE and Western Blot detection, an induced protein with a molecular weight of 63 ku was obtained. It was found by real-time fluorescence quantitative expres- sion that Pun1 gene was expressed at the highest level 30 d after flowering, de- creased then, and could not be detected substantially 40 and 45 d after flowering. [Conclusion] This study provides information and reference for molecular regulation mechanism of Pun1 gene. 展开更多
关键词 PUNGENCY Pun1 gene Transient expression Prokaryotic expression
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Ultrasonic attenuation estimation based on time-frequency analysis 被引量:3
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作者 Gao Feng Wei Jian-Xin Di Bang-Rang 《Applied Geophysics》 SCIE CSCD 2019年第4期414-426,559,共14页
The quality factor(or Q value)is an important parameter for characterizing the inelastic properties of rock.Achieving a Q value estimation with high accuracy and stability is still challenging.In this study,a new meth... The quality factor(or Q value)is an important parameter for characterizing the inelastic properties of rock.Achieving a Q value estimation with high accuracy and stability is still challenging.In this study,a new method for estimating ultrasonic attenuation using a spectral ratio based on an S transform(SR-ST)is presented to improve the stability and accuracy of Q estimation.The variable window of ST is used to solve the time window problem.We add two window factors to the Gaussian window function in the ST.The window factors can adjust the scale of the Gaussian window function to the ultrasonic signal,which reduces the calculation error attributed to the conventional Gaussian window function.Meanwhile,the frequency bandwidth selection rules for the linear regression of the amplitude ratio are given to further improve stability and accuracy.First,the feasibility and influencing factors of the SR-ST method are studied through numerical testing and standard sample experiments.Second,artificial samples with different Q values are used to study the adaptability and stability of the SR-ST method.Finally,a further comparison between the new method and the conventional spectral ratio method(SR)is conducted using rock field samples,again addressing stability and accuracy.The experimental results show that this method will yield an error of approximately 36%using the conventional Gaussian window function.This problem can be solved by adding the time window factors to the Gaussian window function.The frequency bandwidth selection rules and mean slope value of the amplitude ratio used in the SR-ST method can ensure that the maximum error of different Q values estimation(Q>15)is less than 10%. 展开更多
关键词 Q value estimation Time-frequency spectrum ST Window factor Ultrasonic attenuation
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Comparison of Mode Quality Factors for Equilateral Triangular, Square and Rhombus Optical Micro-Resonators
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作者 黄永箴 国伟华 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2001年第2期117-120,共4页
The mode frequencies and the quality factors for the equilateral triangular resonator (ETR), the square resonator (SR) and the rhombus resonator (RR) are numerically calculated by the finite difference time domai... The mode frequencies and the quality factors for the equilateral triangular resonator (ETR), the square resonator (SR) and the rhombus resonator (RR) are numerically calculated by the finite difference time domain technique and the Padé approximation. The numerical results show that the resonant modes confined in an equilateral triangular cavity have much higher quality factors than those in the square or the rhombus cavities. The modes in the ETR are totally confined in transverse direction while those in the SR and RR are only partly confined. For the ETR with the side length of 4μm and the refractive index of 3 2, the mode quality factor of about 5 5×10 3 at the wavelength of 1 55μm has been obtained. 展开更多
关键词 MICRORESONATOR quality factor resonant frequency finite difference time domain technique semiconductor laser
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Spatial and Temporal Variability of N, P and K Balances for Agroecosystems in China 被引量:52
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作者 SHENRun-Ping SUNBo ZHAOQi-Guo 《Pedosphere》 SCIE CAS CSCD 2005年第3期347-355,共9页
Nitrogen, phosphorus, and potassium balances for agroecosystems in China from 1993 to 2001 were calculated at national and provincial levels using statistical data and related parameters, and their spatial and tempora... Nitrogen, phosphorus, and potassium balances for agroecosystems in China from 1993 to 2001 were calculated at national and provincial levels using statistical data and related parameters, and their spatial and temporal variabilities were analyzed with GIS to estimate the potential impacts of nutrient N, P and K surpluses or deficits to soil, water and air. At the national scale, the N and P balances from 1993 to 2001 showed a surplus, with the nitrogen surplus remaining relatively stable from 1997—2001. Although during this period the P surplus pattern was similar to N, it had smaller values and kept increasing as the use of phosphate fertilizer increased year by year. However, K was deficient from 1993 to 2001 even though from 1999 to 2001 the K deficit decreased. The spatial analysis revealed higher N surpluses in the more developed southeastern provinces and lowest in the western and northern provinces where there was less chemical fertilizer input. The serious K deficit mainly occurred in Shanghai and Beijing municipalities, Jiangsu, Zhejiang and Hubei provinces, and Xinjiang autonomous regions. For the years 1992, 1996 and 2001, N surpluses and K deficits had significant positive spatial correlations with per capita gross domestic product (GDP), per capita gross industrial output value, and per capita net income of rural households. This showed that the level of economic development played an important role on nutrient balances in the agroecosystems. 展开更多
关键词 China economic factors NPK balance spatial and temporal variability
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H pylori iceA alleles are disease-specific virulence factors 被引量:8
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作者 Vildan Caner Mustafa Yilmaz +4 位作者 Nadir Yonetci Sevil Zencir Nedim Karagenc Ilknur Kaleli Huseyin Bagci 《World Journal of Gastroenterology》 SCIE CAS CSCD 2007年第18期2581-2585,共5页
AIM: To characterize and compare genotype profiles of H pylori strains isolated from patients with chronic gastritis and duodenal ulcer in western part of Turkey. METHODS: A total of 46 patients [30 chronic gastrit... AIM: To characterize and compare genotype profiles of H pylori strains isolated from patients with chronic gastritis and duodenal ulcer in western part of Turkey. METHODS: A total of 46 patients [30 chronic gastritis (CG) and 16 duodenal ulcer (DU)] who had undergone endoscopy because of dyspeptic complaints were studied. The antral biopsy specimens were evaluated for the presence of Hpylori by rapid urease test and culture, and the genotype profiles were determined by real-time PCR. RESULTS: The cagA gene was observed in 43 (93.5%) isolates. The vacA s1m2 genotype was the predominant subtype, found in 63.3% and 68.7% of isolates in patients with CG and DU, respectively. Twenty (66.6%) isolates from patients with CG were iceA2 positive while the iceA1 was predominant in those with DU (68.8%). In terms of the association of the ice,4 alleles to other genes, both alleles were significantly associated with the cagA vacA slm2 genotype. CONCLUSION: The prevalent circulating genotypes in CG and DU were cagA vacA slm2 iceA2 and cagA vacA slm2 iceA1 genotype, respectively. It was found that cagA vacA slm2 genotype seems to be common virulence factors in both CG and DU while iceA alleles show specificity for gastroduodenal pathologies in this study. 展开更多
关键词 HPYLORI Virulence genes CULTURE REAL-TIMEPCR
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