期刊文献+
共找到45篇文章
< 1 2 3 >
每页显示 20 50 100
大棚黄瓜光合特性因子的相关性分析 被引量:2
1
作者 刘振威 孙涌栋 李新峥 《甘肃农业大学学报》 CAS CSCD 北大核心 2010年第2期79-82,共4页
本试验以大棚黄瓜‘冬美11’为材料,在不同天气下采用美国LI-COR公司生产的LI-6400型便携式光合仪测定了结瓜期的净光合速率,及其与其它影响因子的相关性.结果表明:无论晴天还是阴天,大棚黄瓜的净光合速率、光合有效辐射、气孔导度和蒸... 本试验以大棚黄瓜‘冬美11’为材料,在不同天气下采用美国LI-COR公司生产的LI-6400型便携式光合仪测定了结瓜期的净光合速率,及其与其它影响因子的相关性.结果表明:无论晴天还是阴天,大棚黄瓜的净光合速率、光合有效辐射、气孔导度和蒸腾速率均呈单峰型变化,胞间CO2浓度无论晴天还是阴天均呈"U"形变化,叶温无论晴天还是阴天均呈倒"U"型变化;晴天黄瓜Pn的最优化方程为:y=24.18+0.004 1x1-0.239 0x2+15.6114x3-0.071 8x4,阴天为:y=77.740 4+0.038 6x1+8.035 1x3-2.878 6x5;偏相关分析和通径分析表明:晴天影响因子对Pn影响的顺序为:气孔导度>光合有效辐射>胞间CO2浓度>蒸腾速率.阴天顺序为:光合有效辐射>叶温>气孔导度. 展开更多
关键词 黄瓜 不同天气 光合特性因子 相关性
下载PDF
催化裂化原料特性因子的计算 被引量:2
2
作者 程从礼 《石油炼制与化工》 CAS CSCD 北大核心 2013年第9期34-37,共4页
根据诺谟图,在已知原料完整馏程数据的条件下关联出平均沸点计算式,并关联出原料密度与温度的关系式,据此可以计算特性因子。依据原料的密度和10%馏出体积时的温度数据,建立了原料立方平均沸点的关联式,可以在催化裂化装置原料日常分析... 根据诺谟图,在已知原料完整馏程数据的条件下关联出平均沸点计算式,并关联出原料密度与温度的关系式,据此可以计算特性因子。依据原料的密度和10%馏出体积时的温度数据,建立了原料立方平均沸点的关联式,可以在催化裂化装置原料日常分析数据基础上进行特性因子计算,该关联式的计算结果与实际值的相对误差小于4%,具有良好的模拟精度。 展开更多
关键词 催化裂化原料 特性因子 平均沸点 相对密度 相对分子质量
下载PDF
典型天气下嫁接黄瓜光合特性因子的研究
3
作者 孙丽 李贞霞 +1 位作者 刘振威 李新峥 《内蒙古农业大学学报(自然科学版)》 CAS 北大核心 2009年第4期39-41,共3页
本试验以大棚嫁接黄瓜和自根黄瓜为材料,在不同天气下采用美国LI-COR公司生产的LI-6400型便携式光合仪测定黄瓜结瓜期的光合特性因子并分析其相关性,从而为大棚黄瓜的栽培管理提供科学依据和指导性建议。结果表明:晴天嫁接黄瓜Pn的最优... 本试验以大棚嫁接黄瓜和自根黄瓜为材料,在不同天气下采用美国LI-COR公司生产的LI-6400型便携式光合仪测定黄瓜结瓜期的光合特性因子并分析其相关性,从而为大棚黄瓜的栽培管理提供科学依据和指导性建议。结果表明:晴天嫁接黄瓜Pn的最优化方程:Y=-137.82+0.039 3X1+1.855 5X2-44.297 4X3+0.413 1X4,阴天为:Y=-114.401 3+0.044 6X1+0.223 7X4+1.025 4X5;偏相关和通径分析表明:晴天对Pn的影响顺序为:气孔导度>光合有效辐射>蒸腾速率>胞间CO2浓度。阴天为:光合有效辐射>胞间CO2浓度>叶温。 展开更多
关键词 不同天气 嫁接黄瓜 光合特性因子 相关性
下载PDF
利用偏振特性因子的偏振成像目标探测实验 被引量:5
4
作者 曾恒亮 张孟伟 +1 位作者 刘征 谢宗良 《光电工程》 CAS CSCD 北大核心 2016年第2期22-26,共5页
为了提高目标探测中目标背景对比度,本文利用分焦平面的微偏振元相机同时获取目标四幅偏振状态图像,解算得到斯托克斯矢量,提取目标的偏振度和偏振角成像图像,并结合偏振特性因子F对偏振图像效果进行了改进。结果表明:目标偏振度成像图... 为了提高目标探测中目标背景对比度,本文利用分焦平面的微偏振元相机同时获取目标四幅偏振状态图像,解算得到斯托克斯矢量,提取目标的偏振度和偏振角成像图像,并结合偏振特性因子F对偏振图像效果进行了改进。结果表明:目标偏振度成像图像在原光强图像基础上能够增强目标背景对比度,偏振特性因子成像图像在保留偏振度成像图像增强目标背景对比度的优点的同时,能够提高图像清晰度,扩展图像信息。 展开更多
关键词 同时偏振成像 斯托克斯矢量 偏振特性因子 目标背景对比度
下载PDF
基于频长因子极点分布特征的半波长交流输电线路谐波传输特性分析 被引量:4
5
作者 周胜军 陈畅 +2 位作者 谈萌 杨洪耕 于永军 《高电压技术》 EI CAS CSCD 北大核心 2018年第1期51-58,共8页
线路分布参数特性容易在长线路交流输电中引起(间)谐波放大问题。为了分析半波长输电线路的(间)谐波传输特征,提出基于频长因子的有损半波长交流输电线路频率特性分析方法;通过逐次化简,确定以频率和线路长度乘积作为参变量的有... 线路分布参数特性容易在长线路交流输电中引起(间)谐波放大问题。为了分析半波长输电线路的(间)谐波传输特征,提出基于频长因子的有损半波长交流输电线路频率特性分析方法;通过逐次化简,确定以频率和线路长度乘积作为参变量的有损交流输电线路等效(间)谐波传输计算模型。基于计算模型推导,确定了谐波电压注入有损半波长线路引起的末端谐波电压放大规律;研究频长因子极点分布特征以确定谐振频率;求取谐振幅值包络线以确定各次间谐波不放大的临界条件。为了确定(间)谐波电流注入有损半波长交流输电线路引起的末端(间)谐波电压放大规律,提出参考阻抗为基准的(间)谐波电压放大判别方法。提出的计算模型能够确认,始端的谐波电压、电流注入在任何运行情况下均不会在有损半波长输电线路末端产生谐波电压放大;部分间谐波会出现谐振;线路损耗和负荷情况满足不放大条件时各次间谐波不会放大,否则部分间谐波会放大。PSCAD仿真与模型计算结果之间的误差〈2%,证明了模型的正确性。 展开更多
关键词 半波长 频长因子:传输特性 参考阻抗 (间)谐波放大 谐振
下载PDF
Cloning and Bioinformatics Analysis of Donkey Growth Hormone Gene cDNA 被引量:3
6
作者 苏咏梅 朱文进 朱月华 《Agricultural Science & Technology》 CAS 2011年第4期617-620,共4页
[Objective] The paper aimed to study the donkey GH gene features and functions.[Method] A pair of specific PCR primers was designed for cloning the coding sequence of the donkey GH gene from liver tissue.[Result] 706 ... [Objective] The paper aimed to study the donkey GH gene features and functions.[Method] A pair of specific PCR primers was designed for cloning the coding sequence of the donkey GH gene from liver tissue.[Result] 706 bp fragment was got by RT-PCR amplification.The sequence included a complete open reading frame and encoded 216 amino acids.The protein encoded by donkey GH gene had seven hydrophobic region,seven transmembrane regions and a signal peptide;it's secondary structure had α-helix and irregular curl and three-dimensional solution structure composed of 27-215 amino acids.[Conclusion] GH gene of donkey was very conservative in evolution.The phylogenetic tree constructed basing on CDS sequence is consistent with the results of comparative morphology and comparative physiology. 展开更多
关键词 DONKEY Growth hormone gene Molecular characteristics
下载PDF
对种群增长模型的改进 被引量:21
7
作者 洪伟 吴承祯 闫淑君 《应用与环境生物学报》 CAS CSCD 2004年第1期23-26,共4页
提出有限空间种群增长的Logistic新模型即ds(dt) -1=rs(1-dsθ/k) ,其中参数d描述环境对种群增长的影响 ,参数θ为种内竞争特性参数 .该模型通过种群的竞争特性因子θ控制 ,将指数增长、线性制约、下凹增长和上凸增长非线性制约概括为... 提出有限空间种群增长的Logistic新模型即ds(dt) -1=rs(1-dsθ/k) ,其中参数d描述环境对种群增长的影响 ,参数θ为种内竞争特性参数 .该模型通过种群的竞争特性因子θ控制 ,将指数增长、线性制约、下凹增长和上凸增长非线性制约概括为一个统一的自适应的非线性制约模型 .以格氏栲、红锥种群基面积增长为例 ,运用遗传算法对不同种群增长模型进行最优拟合与比较分析 ,表明新模型能较好地描述格氏栲、红锥种群增长规律 ,为种群增长动态变化的一个理想的机理描述式 .表 4参 展开更多
关键词 种群增长 遗传算法 线性制约 竞争特性因子 种群生态学
下载PDF
深圳地铁5号线车辆蓄电池的选型分析 被引量:14
8
作者 王庆召 刘东广 《电力机车与城轨车辆》 2011年第2期33-34,共2页
文章通过对深圳地铁5号线车辆蓄电池容量选型的分析,对影响蓄电池特性的因子进行了详细的论述,为地铁车辆蓄电池组的选型提供参考。
关键词 地铁车辆 蓄电池 特性因子 选型
下载PDF
TSGF检测临床初步应用 被引量:3
9
作者 安邦权 凌晓午 +1 位作者 王天琼 李贵芳 《中国误诊学杂志》 CAS 2001年第10期1492-1493,共2页
关键词 恶性肿瘤特性生长因子 临床应用 临床诊断 实验室检测
下载PDF
Comparison of Newly Synthetic Hexaploid Wheat with Its Donors on SSR Products 被引量:2
10
作者 张连全 孙根楼 +5 位作者 颜泽洪 陈其皎 袁中伟 兰秀锦 郑有良 刘登才 《Journal of Genetics and Genomics》 SCIE CAS CSCD 北大核心 2007年第10期939-946,共8页
Microsatellites or SSRs as powerful genetic markers have widely been used in genetics and evolutionary biology in common wheat. Because of the high polymorphism, newly synthesized hexaploid wheat has been used in the ... Microsatellites or SSRs as powerful genetic markers have widely been used in genetics and evolutionary biology in common wheat. Because of the high polymorphism, newly synthesized hexaploid wheat has been used in the construction of genetic segregation population for SSR markers, However, data on the evolution of microsatellites during the polyploidization event of hexaploid wheat are limited. In this study, 66 pairs of specific to A/B genome SSR patterns among newly synthesized hexaploid wheat, the donor tetraploid wheat and Aegilops tauschii were compared. The results indicated that most SSR markers were conserved during the polyploidization events of newly synthetic hexaploid wheat, from Triticum turgidum and Ae. tauschii. Over 70% A/B genome specific SSR markers could amplify the SSR sequences from the D genome ofAe. tauschii. Most amplified fragments from Ae, tauschii were detected in synthetic hexaploid at corresponding positions with the same sizes and patterns as in its parental Ae. tauschii. This suggested that these SSR markers, specific for A/B genome in common wheat, could amplify SSR products of D genome besides A/B genome in the newly synthesized hexaploid wheat, that is, these SSR primers specific for A/B genome in common wheat were nonspecific for the A/B genome in the synthetic hexaploid wheat. In addition, one amplified Ae. tauschii product was not detected in the newly synthetic hexaploid wheat. An extra-amplified product was found in the newly synthetic hexaploid wheat. These results suggested that caution should be taken when using SSR marker to genotype newly synthetic hexaploid wheat. 展开更多
关键词 synthetic hexaploid wheat SSR (microsatellite) genome specificity transferability molecular marker
下载PDF
Isolation of a Genomic DNA for Gastrodia Antifungal Protein and Analyses of Its Promoter in Transgenic Tobacco 被引量:3
11
作者 萨其拉 王义琴 +2 位作者 李文彬 张利明 孙勇如 《Acta Botanica Sinica》 CSCD 2003年第2期229-233,共5页
A genomic DNA containing 5'-upstream region and complete open reading frame of a Gastrodia antifungal protein was isolated by screening of a genomic library from Gastrodia elata B1. To investigate the promoter act... A genomic DNA containing 5'-upstream region and complete open reading frame of a Gastrodia antifungal protein was isolated by screening of a genomic library from Gastrodia elata B1. To investigate the promoter activity, the 5'-flanking region - 1 157 lip upstream from the putative transcription start site was fused to the coding sequence of beta-glucuronidase (GUS) gene and transformed into Nicotiana tabacum. The strongest GUS activity was detected in the roots of transgenic tobacco, followed by stems. The leaves only showed a low GUS activity. Furthermore, the promoter established inducible expression pattern in transgenic tobacco upon fungus Trichoderma viride inoculation and jasmonic acid and salicylic acid treatments. 展开更多
关键词 Gastrodia elata Bl. PROMOTER transgenic tobacco organ-specific induced expression
下载PDF
A Simple and Rapid Method to Determine the CO_2/O_2 Specificity Factor for Rubisco
12
作者 李国富 陆巍 +5 位作者 李森 公衍道 张秀芳 张荣铣 周海梦 赵南明 《Acta Botanica Sinica》 CSCD 2000年第12期1304-1307,共4页
A simple and rapid new method is presented to determine the CO 2/O 2 specificity factor for ribulose_1,5_bisphosphate(RuBP) carboxylase/oxygenase (Rubisco). In principle, the quantitative formula, which intrinsicall... A simple and rapid new method is presented to determine the CO 2/O 2 specificity factor for ribulose_1,5_bisphosphate(RuBP) carboxylase/oxygenase (Rubisco). In principle, the quantitative formula, which intrinsically resulted in error or enormous error in all reported methods, was improved to circumvent the problem. In practice, the complicated procedure with radiolabelling and chromatographic separation of 3_phosphoglycerate and 2_phosphoglycolate was substituted by one_step procedure without radiolabelling and chromatographic separation to decrease the random error. The effects of pH, temperature and ionic strength on accuracy of the data and the reliability of the calculation of the CO 2/O 2 specificity factor are also discussed. 展开更多
关键词 RUBISCO CO 2/O 2 specificity factor ERROR accuracL
下载PDF
Mammalian Models Based on RCAS-TVA Technique 被引量:1
13
作者 牛屹东 梁蜀龙 《Zoological Research》 CAS CSCD 北大核心 2008年第3期335-345,共11页
The retroviral vector (RCAS) has been widely used in avian system to study development and diseases, but is not suitable for mammals which do not produce the retrovirus receptor TVA. In this review, we trace the cur... The retroviral vector (RCAS) has been widely used in avian system to study development and diseases, but is not suitable for mammals which do not produce the retrovirus receptor TVA. In this review, we trace the current uses of RCAS-TVA approach in mammalian system with improved strategies, including generation of tv-a transgenic mice, use of soluble TVA receptor and retroviral receptor-ligand fusion proteins, improvement of RCAS vectors, and compare a series of mammalian models in variant studies of gene function, development, oncogenesis and gene therapy. All those studies demonstrate that the RCAS-TVA based mammalian models are powerful tools for understanding the mechanisms and target treating of human diseases. 展开更多
关键词 RCAS vector TVA Specific promoter Transgenic animal Mammalian model
下载PDF
海洋原甲藻属甲藻的研究进展
14
作者 杨美华 陈士林 +3 位作者 吴剑威 吴军 龙丽娟 周伟华 《中国现代中药》 CAS 2007年第11期31-35,共5页
综述近年来国内外原甲藻属甲藻的分类鉴定、生长特性影响因子、化学成分和药理活性等方面的研究进展。
关键词 甲藻 原甲藻属 分类鉴定 生长特性影响因子 化学成分和药理活性
下载PDF
Sequencing and Analysis of Porcine Intrleukin-18 Gene 被引量:1
15
作者 曹素芳 李明 +4 位作者 王岩 刘长斗 朱赞梅 唐桂芬 肖松云 《Agricultural Science & Technology》 CAS 2009年第1期89-92,共4页
[ Objective] To clone the porcine interleukin-18(/L-18) cDNA and explore the immunological effectiveness of porcine IL-18 as an adjuvant of genetic vaccine. [ Method] The spleen lymphccytes were isolated from Henan ... [ Objective] To clone the porcine interleukin-18(/L-18) cDNA and explore the immunological effectiveness of porcine IL-18 as an adjuvant of genetic vaccine. [ Method] The spleen lymphccytes were isolated from Henan three-way cross-breeding pigs. According to the porcine IL-18 gene in GenBank, a pair of specific primers was designed. The full length cDNA of porcine IL-18 was amplified by RT-PCR. Subsequently, porcine IL-18 cDNA was cloned into pGEM-T vector and sequenced and analyzed. [ Result] The porcine IL-18 gene demonstrated an open reading frame of 579 bp encoding an inactive precursor protein with 192 amino acids. The precursor protein had no typical hydrophobic signal peptide and cleaved by interleukin-1 beta (IL-1β) converting enzyme(ICE) in caspase-1 splice site; the porcine mature protein had biological activity: After comparing with other porcine IL-18 genes, the nucleotide sequence homology was over 96% and the deduced amino acid homology was more than 98%. [ Conclusion] A full length procine IL-18 gene was gained. It lays the foundation for porcine IL-18 as an adjuvant of genetic vaccine. 展开更多
关键词 PORCINE Intedeukin-18 SEQUENCING HOMOLOGY
下载PDF
基于米勒矩阵的水下成像技术 被引量:1
16
作者 叶志杰 柳逢春 +1 位作者 安鹏莉 李代林 《科学技术与工程》 2010年第29期7118-7122,共5页
探究在浑浊介质中利用物体的米勒矩阵进行目标识别的技术。米勒矩阵的16个矩阵元可以完整地描述物体的偏振信息,基于各物体不同的偏振特性,不同物体有不同的米勒矩阵。可以以物体退偏特性因子Δ或其中一米勒矩阵元作为灰度值得到一幅图... 探究在浑浊介质中利用物体的米勒矩阵进行目标识别的技术。米勒矩阵的16个矩阵元可以完整地描述物体的偏振信息,基于各物体不同的偏振特性,不同物体有不同的米勒矩阵。可以以物体退偏特性因子Δ或其中一米勒矩阵元作为灰度值得到一幅图像,利用图像的均值、标准差、信息熵和方差对图像进行评价。实验结果表明这种方法能够较大地提高成像质量。 展开更多
关键词 米勒矩阵 水下物体 偏振特性因子
下载PDF
Isolation and characteristics of autoreactive T cells specific to aggrecan G1 domain from rheumatoid arthritis patients 被引量:7
17
作者 LI NING LI DONG QING ZHANG +4 位作者 KUANG YAN ZHOU ANNIE CARTMAN JEAN YVES LEROUX A ROBIN POOLE YI PING ZHANG ( Shanghai Institute of Immunology, Shanghai Second Medical University, Shanghai 200025, China)(Joint Diseases Laboratory, Shriners Hospital, Dep 《Cell Research》 SCIE CAS CSCD 2000年第1期39-49,共11页
Our previous work showed that the cartilage proteoglycan aggrecan could induce an erosive polyarthritis and spondylitis in BALB/c mice and the GI globular domain of the aggrecan (GI) contained the arthritogenic region... Our previous work showed that the cartilage proteoglycan aggrecan could induce an erosive polyarthritis and spondylitis in BALB/c mice and the GI globular domain of the aggrecan (GI) contained the arthritogenic region. To elucidate whether autoreactive T cells to G1 are expressed in rheumatoid arthritis patients, we analyzed the frequency of human G1-specific T cells in the peripheral blood of five rheumatoid arthritis patients and tried to establish G1-reactive T cell lines from these rheumatoid arthritis patients. The results showed that the G1-specific T cells in PBL were detectable at the range of 4.97 ±0.5 ×10-6 in peripheral blood lymphocytes. We have also generated 15 G1-specific T lymphocyte lines from these pateints with a standard split-well method. All these cells expressed fine specificity to human recombinant G1, but not to unrelated antigen. All the 15 lines expressed a panT cell marker and 13 of them selectively used the αβ T cell receptor. Two of them used rye T cell receptor. The 13 of these T cell lines was CD4 positive. One line expressed CD8. One line expressed both CD4 and CD8. Moreover, 14 out of 15 lines expressed the Th-1 cytokine profile, characterized by interferon-γpositivity and IL-4 negativity. No Th-2 type cell line was generated. These data provide strong evidence in favor of the presence of autoreactive T cells in the rheumatoid arthritis pateints. What is the mechanism(s) that these autoreactive T cells attack self-target and whether these G1-specific, Th-1 type T cell lines can induce arthritis in immune deficiency mice are currently under investigation. 展开更多
关键词 rG1-specific T cell lines T cell receptor cytokine profile rheumatoid arthritis.
下载PDF
企业选择外部R&D组织模式的机制探讨
18
作者 王晓靖 曾德明 《科技与管理》 2003年第6期13-16,共4页
探讨了企业如何通过选择不同的组织模式从外部获取所需的技术资源,解释不同组织模式的内在区别,提出由7个特性因子描述的组织模式,并系统地分析内外部的影响因素及对组织模式7个特性因子的影响机制。旨在为企业有效地开展外部R&D提... 探讨了企业如何通过选择不同的组织模式从外部获取所需的技术资源,解释不同组织模式的内在区别,提出由7个特性因子描述的组织模式,并系统地分析内外部的影响因素及对组织模式7个特性因子的影响机制。旨在为企业有效地开展外部R&D提供理论指导。 展开更多
关键词 组织模式 特性因子 影响因素 内部吸收能力 企业 R&D
下载PDF
Clinical Study on the Needling and Drug Treatment of Acute Cerebral Hemorrhage 被引量:2
19
作者 方邦江 周爽 +2 位作者 王升旭 孙国杰 周永生 《Journal of Traditional Chinese Medicine》 SCIE CAS CSCD 2003年第3期191-192,共2页
Researches in recent years have shown that cellular immune factor plays an important role in the generation and development of cerebral hemorrhage1-3.
关键词 Acupuncture Therapy PHYTOTHERAPY Aged Cerebral Hemorrhage Drugs Chinese Herbal FEMALE Humans Male Middle Aged Phosphopyruvate Hydratase Tumor Necrosis Factor-alpha
下载PDF
采用精馏柱对稳定凝析油进行实沸点蒸馏的方法
20
作者 铁牛 祁顺仁 《中国海上油气(地质)》 1994年第4期277-286,共10页
采用精密分馏柱对稳定凝析油进行实沸点蒸馏。所测试的数据可以正确描述油藏流体中液相(稳定凝析油)组成的分布,给出C4-C15^+各级馏分的重量百分比、体积百分比、摩尔百分比、分子量、密度,并能正确计算出C7^+和C11^+特性因子的分... 采用精密分馏柱对稳定凝析油进行实沸点蒸馏。所测试的数据可以正确描述油藏流体中液相(稳定凝析油)组成的分布,给出C4-C15^+各级馏分的重量百分比、体积百分比、摩尔百分比、分子量、密度,并能正确计算出C7^+和C11^+特性因子的分子量及密度,同时也可计算出单脱油的分子量及密度。 展开更多
关键词 精馏柱 稳定凝析油 实沸点蒸馏 C7^+ C11^+ 特性因子 油气藏 相态计算
下载PDF
上一页 1 2 3 下一页 到第
使用帮助 返回顶部