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基因芯片表达数据的标准化策略研究 被引量:17
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作者 伍亚舟 张彦琦 +3 位作者 黄明辉 杨梦苏 曾志雄 易东 《第三军医大学学报》 CAS CSCD 北大核心 2004年第7期594-597,共4页
目的 从统计学、数学和生物信息学相结合的角度 ,探讨针对不同密度基因芯片 (microarray ,genechip)如何进行数据标准化处理与分析 ,寻找表达上有显著性差别的基因。方法 在Excel和Spss软件中 ,采用总强度标准化法 (totalintensitynor... 目的 从统计学、数学和生物信息学相结合的角度 ,探讨针对不同密度基因芯片 (microarray ,genechip)如何进行数据标准化处理与分析 ,寻找表达上有显著性差别的基因。方法 在Excel和Spss软件中 ,采用总强度标准化法 (totalintensitynormalization ,TIN )和局部加权线性回归标准化法 (locallyweightedlinearregressionnormalization ,LWLRN)对高低密度芯片数据进行分析处理。结果 这些方法能有效地减少系统误差产生的影响 ,使处理后的数据更加具有可比性和可靠性。结论 本研究提供的分析方法在减少系统误差基础上能较好地找出芯片上有显著性差异表达的基因 ,不过标准化方法还处于起步和发展的阶段 ,需进一步完善 ;但随着非线性技术的不断完善 ,计算机软硬件的快速发展 。 展开更多
关键词 基因芯片(微阵列) 标准化因子 表达比 显著性差异
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谷氨酸棒杆菌L-天冬氨酸α-脱羧酶在大肠杆菌中的表达及酶转化生产β-丙氨酸 被引量:10
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作者 赵连真 张梁 石贵阳 《微生物学通报》 CAS CSCD 北大核心 2013年第12期2161-2170,共10页
【目的】克隆谷氨酸棒杆菌来源L-天冬氨酸α-脱羧酶基因,实现其在大肠杆菌中的异源表达,并进行酶转化L-天冬氨酸合成β-丙氨酸的研究。【方法】PCR扩增谷氨酸棒杆菌L-天冬氨酸α-脱羧酶基因pand,构建表达载体pET24a(+)-Pand,转化宿主菌... 【目的】克隆谷氨酸棒杆菌来源L-天冬氨酸α-脱羧酶基因,实现其在大肠杆菌中的异源表达,并进行酶转化L-天冬氨酸合成β-丙氨酸的研究。【方法】PCR扩增谷氨酸棒杆菌L-天冬氨酸α-脱羧酶基因pand,构建表达载体pET24a(+)-Pand,转化宿主菌大肠杆菌BL21(DE3),对重组菌进行诱导表达,表达产物经DEAE离子交换层析和G-75分子筛层析纯化后进行酶学性质研究,然后进行酶转化实验,说明底物和产物对酶转化的影响。【结果】重组菌SDS-PAGE分析表明Pand表达量可达菌体总蛋白的50%以上,AccQ·Tag法检测酶活达到94.16 U/mL。该重组酶最适反应温度为55°C,在低于37°C时保持较好的稳定性,最适pH为6.0,在pH 4.0 7.0范围内有较好的稳定性。酶转化实验说明:底物L-天冬氨酸和产物β-丙氨酸对转化反应均有抑制作用;实验建立了较优的酶转化反应方式,在加酶量为每克天冬氨酸3 000 U时,以分批加入固体底物L-天冬氨酸的形式,使100 g/L底物转化率达到97.8%。【结论】重组L-天冬氨酸α-脱羧酶在大肠杆菌中获得高效表达,研究了酶转化生产β-丙氨酸的影响因素,为其工业应用奠定了基础。 展开更多
关键词 L-天冬氨酸α-脱羧酶 Β-丙氨酸 谷氨酸棒杆菌 表达 纯化 转化率
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司法鉴定结果的表述体系与建构——基于贝叶斯定理在鉴定中的展开 被引量:9
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作者 郭华 《中国司法鉴定》 2020年第3期1-7,共7页
司法鉴定携带现代信息技术在诉讼发现真实中发挥的作用越来越显著,以信息数据为基础的概率评估已成为评价证据证明力的重要衡量尺度。然而,我国司法鉴定结果表述的不同,如DNA鉴定结果表述形式繁多,在一定程度上影响了鉴定意见作为法定... 司法鉴定携带现代信息技术在诉讼发现真实中发挥的作用越来越显著,以信息数据为基础的概率评估已成为评价证据证明力的重要衡量尺度。然而,我国司法鉴定结果表述的不同,如DNA鉴定结果表述形式繁多,在一定程度上影响了鉴定意见作为法定证据种类的证明功能。基于贝叶斯定理,探讨DNA鉴定、声纹鉴定、电子数据鉴定等司法鉴定发展及其在证据关联性、证明力上的契合,探索贝叶斯定理以及采用似然比(率)表达鉴定结果这不仅符合鉴定科学性的内在本质,也可能是未来鉴定结果表达的主要选择方式。 展开更多
关键词 司法鉴定 结果表述 贝叶斯定理 似然比 表述体系
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Predominant mucosal IL-8 mRNA expression in non-cagA Thais is risk for gastric cancer 被引量:8
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作者 Sirikan Yamada Shunji Kato +9 位作者 Takeshi Matsuhisa Luksana Makonkawkeyoon Masaru Yoshida Thiraphat Chakrabandhu Nirush Lertprasertsuk Pawit Suttharat Bandhuphat Chakrabandhu Shin Nishiumi Wilaiwan Chongraksut Takeshi Azuma 《World Journal of Gastroenterology》 SCIE CAS 2013年第19期2941-2949,共9页
AIM: To study gastric mucosal interleukine-8 (IL-8) mRNA expression, the cytotoxin-associated gene A (cagA) mutation, and serum pepsinogen (PG)?I/II ratio related risk in Thai gastric cancer.METHODS: There were consen... AIM: To study gastric mucosal interleukine-8 (IL-8) mRNA expression, the cytotoxin-associated gene A (cagA) mutation, and serum pepsinogen (PG)?I/II ratio related risk in Thai gastric cancer.METHODS: There were consent 134 Thai non-cancer volunteers who underwent endoscopic narrow band imaging examination, and 86 Thais advance gastric cancer patients who underwent endoscopic mucosal biopsies and gastric surgery. Tissue samples were taken by endoscopy with 3 points biopsies. The serum PG?I, II, and Helicobacter pylori (H. pylori) immunoglobulin G (IgG) antibody for H. pylori were tested by enzyme-linked immunosorbent assay technique. The histopathology description of gastric cancer and non-cancer with H. pylori detection was defined with modified Sydney Score System. Gastric mucosal tissue H. pylori DNA was extracted and genotyped for cagA mutation. Tissue IL-8 and cyclooxygenase-2 (COX-2) mRNA expression were conducted by real time relative quantitation polymerase chain reaction. From 17 Japanese advance gastric cancer and 12 benign gastric tissue samples, all were tested for genetic expression with same methods as well as Thai gastric mucosal tissue samples. The multivariate analysis was used for the risk study. Correlation and standardized t-test were done for quantitative data, P value < 0.05 was considered as a statistically significant.RESULTS: There is a high non cagA gene of 86.8 per cent in Thai gastric cancer although there are high yields of the East Asian type in the positive cagA. The H. pylori infection prevalence in this study is reported by combined histopathology and H. pylori IgG antibody test with 77.1% and 97.4% of sensitivity and specificity, respectively. The serum PG?I/II ratio in gastric cancer is significantly lower than in the non-cancer group, P = 0.045. The serum PG?I/II ratio of less than 3.0 and IL-8 mRNA expression ≥ 100 or log10 ≥ 2 are significant cut off risk differences between Thai cancer and non-cancer, P = 0.03 and P < 0.001, respectively. There is a significantly lower PG 展开更多
关键词 Gastric cancer CagA mutation Interleukine-8 mRNA expression Helicobacter pylori Pepsinogen I/II ratio
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2124铝合金全范围裂纹扩展速率表达式 被引量:7
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作者 严芳芳 王泓 +1 位作者 张建国 刘小山 《热加工工艺》 CSCD 北大核心 2011年第16期34-36,共3页
研究了2124铝合金TL取向不同应力比下的疲劳裂纹扩展行为、疲劳裂纹扩展门槛值,并计算了不同应力比下的临界应力强度因子。分析了应力比对疲劳裂纹扩展速率的影响,并用有效应力强度因子和有效门槛值对全范围裂纹扩展速率表达式进行修正... 研究了2124铝合金TL取向不同应力比下的疲劳裂纹扩展行为、疲劳裂纹扩展门槛值,并计算了不同应力比下的临界应力强度因子。分析了应力比对疲劳裂纹扩展速率的影响,并用有效应力强度因子和有效门槛值对全范围裂纹扩展速率表达式进行修正,得到了描述2124铝合金TL取向疲劳裂纹扩展全范围的表达式。该公式能够很好表征不同应力比下2124铝合金TL取向的疲劳裂纹扩展行为。 展开更多
关键词 疲劳裂纹扩展速率表达式 2124铝合金 应力比 有效应力强度因子 门槛值
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不同氮素形态及配比对黄瓜生长和性别分化的影响 被引量:4
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作者 寿森炎 楼惠宁 董伟敏 《浙江农业学报》 CSCD 1995年第3期226-229,共4页
采用基质培养,研究不同氮素形态及配比对黄瓜生长和性别分化的影响,结果表明:用纯NO-N营养液处理,黄瓜植株营养生长旺盛.当NH-N占25%和50%时,则明显促进黄瓜的生殖生长,表现为第一雌花比纯NO-N处理低0.4和0.6节,雌花率增... 采用基质培养,研究不同氮素形态及配比对黄瓜生长和性别分化的影响,结果表明:用纯NO-N营养液处理,黄瓜植株营养生长旺盛.当NH-N占25%和50%时,则明显促进黄瓜的生殖生长,表现为第一雌花比纯NO-N处理低0.4和0.6节,雌花率增加23.9和31.0个百分点,单株产量增加35.3%和28.7%;叶片和果实中矿物元素钾、铁、锌分别增加0.02~1.41%、0.11~1.24μg/gDW、37.6~47.0μg/gDW,镁、锰、铜差异不大.黄瓜生育期不同对氮素形态的敏感性有差异,幼苗期较生长旺期不敏感. 展开更多
关键词 黄瓜 氮素形态 性别 生长 分化
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节能压榨过滤技术的研究进展 被引量:6
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作者 都丽红 朱企新 《化工进展》 EI CAS CSCD 北大核心 2009年第8期1307-1312,共6页
从固液分离技术发展趋势及当今全球能源紧张、资源短缺的实际出发,分析了节能型压榨过滤机发展的必然,介绍了压榨过滤理论研究的进展;并用试验数据重点介绍了厢式压榨过滤机不同压力、不同压榨起始点工程应用试验的结果及比较,为选择适... 从固液分离技术发展趋势及当今全球能源紧张、资源短缺的实际出发,分析了节能型压榨过滤机发展的必然,介绍了压榨过滤理论研究的进展;并用试验数据重点介绍了厢式压榨过滤机不同压力、不同压榨起始点工程应用试验的结果及比较,为选择适宜操作条件进行了探讨;同时还介绍了国外立式压榨过滤机在工业应用中提高产量与节能方面的一些试验数据和情况。 展开更多
关键词 压榨过滤 隔膜 压榨比 脱液 可压缩滤饼
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Ki67表达比例对乳腺癌患者预后影响的Meta分析 被引量:6
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作者 张月严 李强 +1 位作者 栗海涛 张勇 《现代肿瘤医学》 CAS 2019年第11期1890-1894,共5页
目的:系统评价Ki67表达比例对乳腺癌患者预后的影响,尤其是对无病生存期(DFS)的影响。为临床应用提供循证医学依据。方法:计算机检索PubMed、Embase、Web of Science、Cochrane Library、中国期刊全文数据库(CNKI)、维普数据库(VIP)、... 目的:系统评价Ki67表达比例对乳腺癌患者预后的影响,尤其是对无病生存期(DFS)的影响。为临床应用提供循证医学依据。方法:计算机检索PubMed、Embase、Web of Science、Cochrane Library、中国期刊全文数据库(CNKI)、维普数据库(VIP)、万方数据库以及中国生物医学文献数据库(CBM)。应用RevMan 5.3软件对所纳入的数据进行统计学分析。结果:共纳入8篇文献,合计15 643例患者。Meta分析结果显示,纳入文献中的Ki67高比例表达组患者的DFS(HR=1.86,95%CI=1.31~2.65)要低于Ki67低比例表达组,差异有统计学意义。亚组分析中,以种族分亚组的结果与上述类似,差异也有统计学意义;以Ki67表达临界值分亚组,Ki67表达临界值为30%的亚组差异没有统计学意义,表达临界值为其他值的亚组差异有统计学意义。结论:本研究Meta分析显示,Ki67是乳腺癌的一种不良预后因子,Ki67高比例表达的患者有着更低的DFS。 展开更多
关键词 KI67 表达比例 乳腺癌 DFS 预后
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Regulatory Genes Through Robust-SNR for Binary Classification Within Functional Genomics Experiments
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作者 Muhammad Hamraz Dost Muhammad Khan +6 位作者 Naz Gul Amjad Ali Zardad Khan Shafiq Ahmad Mejdal Alqahtani Akber Abid Gardezi Muhammad Shafiq 《Computers, Materials & Continua》 SCIE EI 2023年第2期3663-3677,共15页
The current study proposes a novel technique for feature selection by inculcating robustness in the conventional Signal to noise Ratio(SNR).The proposed method utilizes the robust measures of location i.e.,the“Median... The current study proposes a novel technique for feature selection by inculcating robustness in the conventional Signal to noise Ratio(SNR).The proposed method utilizes the robust measures of location i.e.,the“Median”as well as the measures of variation i.e.,“Median absolute deviation(MAD)and Interquartile range(IQR)”in the SNR.By this way,two independent robust signal-to-noise ratios have been proposed.The proposed method selects the most informative genes/features by combining the minimum subset of genes or features obtained via the greedy search approach with top-ranked genes selected through the robust signal-to-noise ratio(RSNR).The results obtained via the proposed method are compared with wellknown gene/feature selection methods on the basis of performance metric i.e.,classification error rate.A total of 5 gene expression datasets have been used in this study.Different subsets of informative genes are selected by the proposed and all the other methods included in the study,and their efficacy in terms of classification is investigated by using the classifier models such as support vector machine(SVM),Random forest(RF)and k-nearest neighbors(k-NN).The results of the analysis reveal that the proposed method(RSNR)produces minimum error rates than all the other competing feature selection methods in majority of the cases.For further assessment of the method,a detailed simulation study is also conducted. 展开更多
关键词 Median absolute deviation(MAD) classification feature selection high dimensional gene expression datasets signal to noise ratio
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基于自然语言理解的电力调度文本检索方法研究及应用
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作者 张小韬 季小龙 《黑龙江电力》 CAS 2023年第5期466-470,共5页
电力调度文本中含有大量的价值信息,针对现行调度员多依靠手工方式查阅信息导致工作量大、效率低的问题,提出一种基于自然语言理解的电力调度文本检索方法。基于正则表达式建立电力调度文本解析模型,抽取电力文本关键信息及与关键信息... 电力调度文本中含有大量的价值信息,针对现行调度员多依靠手工方式查阅信息导致工作量大、效率低的问题,提出一种基于自然语言理解的电力调度文本检索方法。基于正则表达式建立电力调度文本解析模型,抽取电力文本关键信息及与关键信息对应的解释内容,将电力文本解析内容以“实体-关系-实体”方式融合,建立电力调度文本知识图谱。提出电力调度文本信息相似度计算方法,通过计算待检索电力文本信息与电力调度文本知识图谱中实体间的相似距离,判定电力文本信息检索结果。通过对某地区电力调度文本的验证,得出所提基于自然语言理解的电力调度文本检索方法具有较高的检索准确率和检索效率,具有广泛的工程应用前景。 展开更多
关键词 电力调度文本 自然语言理解 正则表达式 知识图谱 文本相似度 查准率
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Functional design of wind turbine airfoils based on roughness sensitivity characteristics 被引量:4
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作者 王旭东 Xia Hongjun 《High Technology Letters》 EI CAS 2014年第4期442-445,共4页
To improve aerodynamic performance of wind turbine airfoils,the shape profile characteristic of the airfoil is investigated.Application of conformal transformation,one functional and integrated expression of wind turb... To improve aerodynamic performance of wind turbine airfoils,the shape profile characteristic of the airfoil is investigated.Application of conformal transformation,one functional and integrated expression of wind turbine airfoils is presented.Using the boundary layer theory,the aerodynamic model with roughness of wind turbine airfoils is introduced by studying flow separation around the airfoil.Based on the shape expression and aerodynamic performance of airfoils,the function design of wind turbine airfoils is carried out that the maximum lift-drag ratio and low roughness sensitivity are designed objects.Three wind turbines airfoils with different thickness are gained which are used at tip part of blades.As an example,the aerodynamic performance of one designed airfoil with relative thickness of 15%is simulated in different conditions of clean surface,rough surface,laminar flow and turbulent flow.The comparison of aerodynamic performance between the designed airfoil and one popular NACA airfoil is completed which can verify the better performance of the designed airfoil and reliability of the designed method. 展开更多
关键词 wind turbine airfoils integrated expression lift-drag ratio roughness sensitivity function design
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The Co-Involvement of Light and Air Temperature in Regulation of Sex Expression in Monoecious Cucumber (<i>Cucumis sativus</i>L.) 被引量:1
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作者 Lina Wang Xiaoyu Yang +1 位作者 Zhonghai Ren Xiufeng Wang 《Agricultural Sciences》 2014年第10期858-863,共6页
The combination effects of light and air temperature, which were expressed as photothermal ratio (PTR), on the growth and sex expression of three monoecious cucumbers (Cucumis sativus L. cv. “Xintaimici”, “Jinyan 3... The combination effects of light and air temperature, which were expressed as photothermal ratio (PTR), on the growth and sex expression of three monoecious cucumbers (Cucumis sativus L. cv. “Xintaimici”, “Jinyan 3” and “Jinyan 4”) were studied with hydroponics in this research. The results showed that with the increase of PTR, different growth responses were observed in the three cucumber cultivars. In contrast, high PTR (H-PTR, 0.86 mol·m-2·degree-day-1) significantly increased the total number of female nodes and decreased the total number of male nodes of the three monoecious cucumber cultivars compared with cucumbers grown under low PTR (L-PTR, 0.64 mol·m-2·degree-day-1). More photoassimilate was partitioned to fruits of three cucumber cultivars with the increase of PTR, indicating that PTR-mediated femaleness of monoecious cucumber might be attributed to the enhancement of photoassimilate translocation from source organs to sink organs. 展开更多
关键词 CUCUMBER Growth PHOTOTHERMAL ratio Sex expression
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EFFECT OF THE POISSON RATIO ON THE PERFECTLY PLASTIC STRESS FIELD AT A STATIONARY PLANE-STRAIN CRACK TIP
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作者 林拜松 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1992年第3期289-295,共7页
Under the condition that all the perfectly plastic stress components at a crack tip are the functions of ? only, making use of equilibrium equations and Von-Mises yield condition containing Poisson ratio, in this pape... Under the condition that all the perfectly plastic stress components at a crack tip are the functions of ? only, making use of equilibrium equations and Von-Mises yield condition containing Poisson ratio, in this paper, we derive the generally analytical expressions of perfectly plastic stress field at a stationary plane-strain crack tip. Applying these generally analytical expressions to the concrete cracks, the analytical expressions of perfectly plastic stress fields at the stationary tips of Mode I, Mode II and Mixed-Mode I-II plane-strain cracks are obtained. These analytical expressions contain Poisson ratio. 展开更多
关键词 Poisson ratio PLANE-STRAIN stationary crack-tip perfectly-plastic stress fields generally analytical expression
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Multi-carbohydrase enzymes improve feed energy in broiler diets containing standard or low crude protein 被引量:1
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作者 Sosthene Musigwa Natalie Morgan +3 位作者 Robert A.Swick Pierre Cozannet Sarbast K.Kheravii Shu-Biao Wu 《Animal Nutrition》 SCIE CSCD 2021年第2期496-505,共10页
This study evaluated the effect of multi-carbohydrase(MC)on energy and nitrogen(N)balance and gene expression in broilers fed diets with different crude protein(CP)contents.The study employed a 2×2 factorial arra... This study evaluated the effect of multi-carbohydrase(MC)on energy and nitrogen(N)balance and gene expression in broilers fed diets with different crude protein(CP)contents.The study employed a 2×2 factorial arrangement of treatments.The factors were presence or absence of MC,and standard(SCP)or low(LCP)dietary CP concentration.A 3-phase feeding program was used,including starter(0 to 7 d),grower(8 to 17 d)and finisher(18 to 28 d)phases.The study was undertaken in closed calorimetry chambers.Each of the 4 dietary treatments was replicated 8 times in total across 2 runs,with 2 birds per replicate(n=64).Data for energy partitioning and N balance were collected from d 25 to 28.On d 28,birds were euthanized to collect muscle and intestinal tissue samples for gene expression.The results showed that the MC increased apparent metabolizable energy(AME,P<0.01)and net energy(NE,P<0.05),and reduced the feed conversion ratio(FCR,P<0.01)in all diets.The proportion of energy retained as fat per total energy retention(REf/RE)was positively correlated with feed AME and NE(r=0.541,P<0.01 and r=0.665,P<0.001,respectively),suggesting that feed energy augmented with increased fat gain.Muscle ATP synthase subunit alpha(ATPSA1W)gene expression had a positive cor-relation with REf/RE and feed NE(r=0.587,P<0.001 and r=0.430,P<0.05,respectively).Similarly,muscle peroxisome proliferator-activated receptor gamma coactivator 1 alpha(PGC-1A)expression was negatively correlated with weight gain and positively correlated with FCR(r-0.451,P<0.05 and r-0.359,P<0.05,respectively).These correlations show that over-expressions of muscle genes related to energy production reduce bird performance.This study demonstrated that MC increase dietary energy utilization,regardless of dietary CP concentration.However,the energy released by the enzymes in-creases feed energy-to-CP ratio,meaning there is excess energy that is then deposited as body fat.This suggests that supplemental MC in broiler feeds is beneficial if diets are formulated to contain margina 展开更多
关键词 Apparent metabolizable energy Net energy Nitrogen efficiency Gene expression Energy-to-protein ratio
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基于簇聚类和游程编码的正则表达式压缩算法 被引量:1
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作者 杨嘉佳 姜腊林 +2 位作者 姜磊 戴琼 谭建龙 《计算机工程》 CAS CSCD 2014年第8期282-287,292,共7页
基于簇聚类的确定型有穷自动机(DFA)压缩算法,即ClusterFA算法,解决了正则表达式匹配中的空间爆炸问题,但该算法的分组个数取理想值较为困难,且其类中心向量表的每一行中连续重复转移状态出现频率较高。针对该问题,提出一种改善ClusterF... 基于簇聚类的确定型有穷自动机(DFA)压缩算法,即ClusterFA算法,解决了正则表达式匹配中的空间爆炸问题,但该算法的分组个数取理想值较为困难,且其类中心向量表的每一行中连续重复转移状态出现频率较高。针对该问题,提出一种改善ClusterFA算法的方案En_ClusterFA。提取类中心向量表行与行之间相同的首尾部分,并对其进行游程编码以建立索引表,对类中心向量表余下部分的转移状态进行游程编码。利用该方案对Bro,Snort和L7-filter规则集进行测试,实验结果表明,除了L7_2和L7_6规则集的压缩率分别提高到96.1%和98.1%之外,其他规则集的压缩率都提高到99%以上。与ClusterFA算法的压缩率相比,En_ClusterFA平均提高了4%,证明En_ClusterFA能够有效地提高DFA的压缩效率。 展开更多
关键词 正则表达式 ClusterFA算法 确定型有穷自动机 游程编码 压缩率 吞吐率
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Normalization strategy of microarray gene expression data
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作者 伍亚舟 张玲 +2 位作者 黄明辉 杨梦苏 易东 《Journal of Medical Colleges of PLA(China)》 CAS 2007年第4期195-200,共6页
Objective: To discuss strategies and methods of normalization on how to deal with and analyze data for different chips with the combination of statistics, mathematics and bioinformatics in order to find significant d... Objective: To discuss strategies and methods of normalization on how to deal with and analyze data for different chips with the combination of statistics, mathematics and bioinformatics in order to find significant difference genes. Methods: With Excel and SPSS software, high or low density chips were analyzed through total intensity normalization (TIN) and locally weighted linear regression normalization (LWLRN). Results: These methods effectively reduced systemic errors and made data more comparable and reliable. Conclusion: These methods can search the genes of significant difference, although normalization methods are being developed and need to be improved further. Great breakthrough will be obtained in microarray data normalization analysis and transformation with the development of non-linear technology, software and hardware of computer. 展开更多
关键词 gene chip normalization factor expression ratio significant difference
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面向脸部表情识别的Gabor特征选择方法 被引量:19
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作者 姚伟 孙正兴 张岩 《计算机辅助设计与图形学学报》 EI CSCD 北大核心 2008年第1期79-84,共6页
针对人脸表情识别中Gabor特征向量的高维度信息冗余问题,提出了一个2层Gabor特征选择方法.该方法首先利用改进方差比率作为评估特征的区分能力对高维向量进行过滤,然后对过滤得到的特征子集进行Ad-aBoost特征选择,以挑选出最具区分度的... 针对人脸表情识别中Gabor特征向量的高维度信息冗余问题,提出了一个2层Gabor特征选择方法.该方法首先利用改进方差比率作为评估特征的区分能力对高维向量进行过滤,然后对过滤得到的特征子集进行Ad-aBoost特征选择,以挑选出最具区分度的特征,从而降低了Gabor特征的表示维度.实验结果验证了所提方法的有效性,在训练时间和识别性能两者之间取得了较好的平衡. 展开更多
关键词 表情识别 GABOR特征 特征选择 方差率 ADABOOST 支持向量机
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基于信噪比与邻域粗糙集的特征基因选择方法 被引量:13
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作者 徐久成 李涛 +1 位作者 孙林 李玉惠 《数据采集与处理》 CSCD 北大核心 2015年第5期973-981,共9页
鉴于传统基因选择方法会选出大量冗余基因从而导致样本预测准确率较低,提出了一种基于信噪比与邻域粗糙集的特征基因选择方法(Signal noise ration and the neighborhood rough set,SNRS)。首先采用信噪比指标获得分类能力较强的预选特... 鉴于传统基因选择方法会选出大量冗余基因从而导致样本预测准确率较低,提出了一种基于信噪比与邻域粗糙集的特征基因选择方法(Signal noise ration and the neighborhood rough set,SNRS)。首先采用信噪比指标获得分类能力较强的预选特征子集;然后利用邻域粗糙集约简算法对预选特征子集进行寻优;最后采用不同的分类器对特征基因子集进行分类。通过实验表明,该方法能够克服传统分类算法精度不高的缺陷,并且能够在较少的特征基因下取得较高的分类精度,验证了该方法的可行性和有效性。 展开更多
关键词 肿瘤基因表达谱 信噪比 邻域粗糙集 特征选择
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Optimization of Agrobacterium tumefaciens-Mediated Transformation Systems in Tea Plant(Camellia sinensis) 被引量:11
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作者 LV Qianru CHEN Changsong +5 位作者 XU Yijuan HU Shunkai WANG Le SUN Kang CHEN Xuan LI Xinghui 《Horticultural Plant Journal》 SCIE 2017年第3期105-109,共5页
In this study, an efficient plant regeneration protocol in vitro and transformation by Agrobacterium-mediated method of Camellia sinensis was achieved, which would lay the foundation for genetic improvement of tea pla... In this study, an efficient plant regeneration protocol in vitro and transformation by Agrobacterium-mediated method of Camellia sinensis was achieved, which would lay the foundation for genetic improvement of tea plant by genetic engineering technology. The cotyledon callus of C.sinensis were used as the receptors for transformation by Agrobacterium tumefaciens EHA105 containing PS1aG-3. Some factors which affected the result of Agrobacterium-mediated transformation of C. sinensis were studied on the basis of GUS transient expression system. The optimum system of Agrobacterium-mediated transformation was that the cotyledon callus were pre-cultured for 3 d, and then infected by EHA105 for 15 min followed by 3 d co-culture in the dark on the YEB medium containing 150 μmol·L^(-1) acetosyringone(AS). The transient expression rate of GUS gene was 62.6%. After being delayed selective culture for 3 d, infected callus were transferred into the differentiation medium and the root induction medium both of which were supplemented with 100 mg·L^(-1) spectinomycin, and then resistant seedlings of C. sinensis were obtained. The conversion rate was 3.6%. 展开更多
关键词 Camellia sinensis cotyledon callus AGROBACTERIUM-MEDIATED GUS transient expression transformation ratio
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基于电弧电流边际谱能量比的输电线路永久性故障识别方法 被引量:12
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作者 李博通 赵盛 +2 位作者 李斌 姚斌 李宝伟 《电力系统及其自动化学报》 CSCD 北大核心 2018年第10期61-67,共7页
为避免输电线路故障发生之后采用自动重合闸重合于永久性故障后对系统造成危害,在系统故障跳闸后准确判别故障性质以实现自适应重合闸具有重要意义。针对三相交流输电系统,分析了单相接地故障时故障电弧的特性,利用故障发生后的双端电... 为避免输电线路故障发生之后采用自动重合闸重合于永久性故障后对系统造成危害,在系统故障跳闸后准确判别故障性质以实现自适应重合闸具有重要意义。针对三相交流输电系统,分析了单相接地故障时故障电弧的特性,利用故障发生后的双端电气量推导出电弧电流的特征表达式。通过对该表达式的计算结果序列进行边际谱能量分析,提出了基于电弧电流边际谱能量比的永久性故障识别方法。仿真验证表明,该故障识别方法能够有效可靠地识别永久性故障与瞬时性故障,且不受故障位置、过渡电阻影响。 展开更多
关键词 电弧电流特征表达式 故障电弧 永久性故障 瞬时性故障 边际谱能量比 故障识别
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