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Search Results: 1 - 10 of 47683 matches for " 丁 超 "
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海外网络对跨国企业绩效影响的实证研究

科技进步与对策 , 2015, DOI: 10.6049/kjjbydc.2015040818
Abstract: 随着经济全球化和知识经济的迅猛发展,海外网络成为跨国创业企业优化网络,提高创业成功率、培育核心竞争力、有效参与国际竞争的重要方式。基于创业阶段差异的动态视角,构造海外网络对于跨国创业企业绩效影响的分析框架。实证结果表明:在创业生存阶段,海外市场网络嵌入对跨国创业企业绩效具有显著正向影响,而海外技术网络嵌入对跨国创业企业绩效影响不显著;在创业成长阶段,海外技术网络嵌入正向影响跨国创业企业绩效,而海外市场网络对跨国创业企业绩效影响不显著。海外网络创业阶段成长绩效财务绩效跨国企业
卷层云?还是透光高层云?

气象 , 1984, DOI: 10.7519/j.issn.1000-0526.1984.7.014
Abstract:
固态降水及冬季冻结现象的观测

气象 , 2005, DOI: 10.7519/j.issn.1000-0526.2005.1.021
Abstract:
电磁铁衔铁被磁化后的修复

气象 , 1985, DOI: 10.7519/j.issn.1000-0526.1985.07.013
Abstract:
双基因敲除减毒单增李斯特菌(?actA/?inlB)的构建及其生物学初步鉴定

- , 2016, DOI: 10.13982/j.mfst.1673-9078.2016.7.011
Abstract: 减毒单增李斯特菌具有成为疫苗活载体的潜力,可同时引起MHCⅠ和MHCⅡ类抗原递呈系统,具有强烈激发CD8+和CD4+细胞免疫的能力。构建毒力基因缺失菌株进而评估其生物活性对于其作为疫苗活载体的开发尤为重要。本文采用同源重组技术构建单缺失菌株Lm-△actA和双缺失菌株Lm-△actA△/inlB ,从生长状态、毒力基因表达和对HepG2细胞侵袭能力方面探讨减毒菌株生物学特性。生长活性测定显示两种减毒菌株和野生型Lm(EGD-e)三者生长状况无差异;实时定量PCR结果显示actA基因缺失后,inlA基因表达水平上升两倍;actA和inlB基因双缺失后,plcB和hly基因的表达水平都有较大幅度的上升;侵袭HepG2细胞结果显示actA基因缺失后侵袭能力增强、actA和inlB基因共同缺失后侵袭能力减弱。因此,减毒菌株的构建及其生物特性研究不仅对食源性致病菌Lm致病机理具有重要意义,也为构建预防人类和动物疫病的疫苗载体奠定了基础。
Attenuated Listeria monocytogenes (Lm) has the potential to become a live vaccine vector. It can also produce major histocompatibility complex (MHC)Ⅰ and MHC Ⅱ antigen presentation systems, and significantly stimulate immunity in cluster of differentiation (CD)8+ and CD4+ cells. The construction of avirulent gene deletion strains and the subsequent evaluation of their biological activity are crucial for the development of live vaccine vectors. Homologous recombination technology was used to construct Lm-?actA and Lm-?actA/?inlB strains, and the biological activities of attenuated strains were explored in terms of growth, virulence gene expression, and the capacity to invade HepG2 cells. The results showed that no difference in growth was found among the attenuated strains Lm-?actA, Lm-?actA/?inlB, and wild type Lm (EGD-e). Real time quantitative polymerase chain reaction (PCR) results showed that inlA expression was enhanced two-fold after the actA gene was deleted. The expression of plcB and hly genes was significantly elevated when actA and inlB genes were simultaneously deleted. The HepG2 cell invasion assay showed that the invasive capacity was enhanced after the actA gene was deleted and was weakened after deleting actA and inlB genes. Therefore, the construction of attenuated strains and study of their biological properties is not only important for understanding the pathogenesis of food-borne Lm, but also lays a foundation for the construction of vaccine vectors for the prevention of human and animal diseases.
距离模式识别图的判定
DETERMINATION OF DISTANCE PATTERN DISTINGUISHING GRAPHS

作者,
- , 2017,
Abstract: 本文研究了几类图的距离模式识别性.利用构造法,求出了它们的距离模式识别集和距离模式识别数,提出距离模式识别率的概念,推广了距离模式识别数的概念.
In this paper, some classes of graphs are studied on distance pattern distinguishing. By the method of structuring, their distance pattern distinguishing sets and the distance pattern distinguishing numbers are given. The concept of distance pattern distinguishing rate is proposed, which extends the concept of distance pattern distinguishing number
千岛湖陆桥岛屿鸟类集团对栖息地片段化的敏感性及其季节变化
,志锋?,平?
生态学报 , 2015,
Abstract: 为探究千岛湖陆桥岛屿不同鸟类集团对栖息地片段化敏感性的差异和季节变化,于2009年4月-2012年1月鸟类繁殖季(4、5、6月)和冬季(11、12、1月)对千岛湖41个陆桥岛屿鸟类集团进行了研究。结果表明,冬季杂食鸟对片段化敏感性高于食虫鸟,繁殖季时二者无显著差异,繁殖季和冬季时下层鸟对片段化敏感性均高于林冠鸟,冬季留鸟对片段化敏感性高于候鸟,繁殖季则无显著差异。杂食鸟和留鸟对片段化敏感性存在季节差异,而食虫鸟、林冠鸟、下层鸟和候鸟对片段化敏感性均无季节差异。不同鸟类集团对栖息地片段化敏感性的差异和季节变化规律,有助于人们在栖息地管理和保护区设计时采取更有针对性的鸟类保护措施。
比特交织空时编码调制分集研究
,,
北京邮电大学学报 , 2008, DOI: 10.13190/jbupt.200803.115.290
Abstract: 提出了比特交织空时编码调制分集方案,给出了调制分集的实现方法和获得最大分集增益的星座最优旋转角,分析了调制分集对比特交织空时编码调制迭代译码(BI-STCM-ID)系统性能的影响,得到了引入调制分集后系统的解码比特度量以及成对差错概率的解析表达式. 理论分析和仿真结果表明,调制分集极大地改善了BI-STCM-ID系统在Rayleigh信道下的性能,同时,空时分集与调制分集的结合,对改善快衰落信道和慢衰落信道的性能具有相互补充的效果.
热轧组织对高强度冷轧TRIP钢力学性能的影响
,,张君
东北大学学报:自然科学版 , 2015, DOI: 10.3969/j.issn.1005-3026.2015.03.013
Abstract: 采用扫描电镜、X射线衍射、拉伸试验等方法研究了热轧组织对含Al冷轧TRIP钢热处理后组织与力学性能的影响.通过不同轧后冷却方式得到三种不同的热轧组织:组织细小的F+P+B试样;F+B试样;F+P试样.热轧组织细小的试样热处理后含有较多的粒状贝氏体和较少的残余奥氏体组织,强度最高达到996MPa,延伸率为20.8%.另两种试样组织为多边形铁素体、粒状贝氏体以及较多的残余奥氏体组织.F+B试样延伸率可达29.4%,强塑积为26812.8MPa·%.F+P试样热处理后带状组织的危害不易消除.
军民科技创新资源信息平台建设路径与运行机制研究
董志良,
科技进步与对策 , 2011,
Abstract: 在探讨军民合作信息交流障碍,并提出信息交流平台建设目标和建设原则的基础上,提出了军民科技创新资源信息服务平台建设中的风险控制方案,同时提出平台的建设路径。军民合作创新资源信息服务平台风险控制建设路径运行机制
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