大熊猫(Ailuropoda melanoleuca)及其生境环境一直受到广泛关注,而主食竹是关系大熊猫生存和发展的关键因素。文章基于中国知网(CNKI)全文数据库和Web of Science核心合集数据库,采用可视化工具VOS viewer和SATI对国内外大熊猫主食竹的...大熊猫(Ailuropoda melanoleuca)及其生境环境一直受到广泛关注,而主食竹是关系大熊猫生存和发展的关键因素。文章基于中国知网(CNKI)全文数据库和Web of Science核心合集数据库,采用可视化工具VOS viewer和SATI对国内外大熊猫主食竹的相关文献进行计量分析。结果表明国内研究热点主要有关于竹种的分类和分布调查、大熊猫自然保护区的评价等,国外研究热点主要有主食竹的分类学、大熊猫对主食竹的选择性、大熊猫栖息地评价等内容。上述结果揭示了大熊猫主食竹研究的演变特征与发展趋势,有助于加深对该研究领域的整体认识。展开更多
大熊猫是一种非常古老而珍贵的濒危物种,与人类相比,大熊猫经历了800万年残酷的生存考验后留存至今。自20世纪80年代以来,关于大熊猫濒临灭绝问题研究日益增多。近10年来全球43个国家的研究者在579种国内外知名杂志刊物上发表学科前端...大熊猫是一种非常古老而珍贵的濒危物种,与人类相比,大熊猫经历了800万年残酷的生存考验后留存至今。自20世纪80年代以来,关于大熊猫濒临灭绝问题研究日益增多。近10年来全球43个国家的研究者在579种国内外知名杂志刊物上发表学科前端高水平文章,引起世界各国学者对野生大熊猫及其栖息地保护工作的高度重视。本论文主要收集2010—2019年国内外广大学者在大熊猫相关方面研究发表文献,据统计Web of Science引文数据库中1112篇外文文献与中国知网(CNKI)期刊数据库收集到中文核心文献478篇,对这些文章从不同学科领域、发表年份、作者隶属单位、研究内容、期刊影响因子进行分类统计。近3年,大熊猫文献研究深度和文章数量都有明显提高,研究内容不断多元化,多学科科学的研究方向成为其主流。展开更多
The weight hierarchy of a linear[n;k;q]code C over GF(q) is the sequence(d_1,d_2,…,d_k)where d_r is the smallest support of any r-dimensional subcode of C. "Determining all possible weight hierarchies of general...The weight hierarchy of a linear[n;k;q]code C over GF(q) is the sequence(d_1,d_2,…,d_k)where d_r is the smallest support of any r-dimensional subcode of C. "Determining all possible weight hierarchies of general linear codes" is a basic theoretical issue and has important scientific significance in communication system.However,it is impossible for g-ary linear codes of dimension k when q and k are slightly larger,then a reasonable formulation of the problem is modified as: "Determine almost all weight hierarchies of general g-ary linear codes of dimension k".In this paper,based on the finite projective geometry method,the authors study g-ary linear codes of dimension 5 in class IV,and find new necessary conditions of their weight hierarchies,and classify their weight hierarchies into6 subclasses.The authors also develop and improve the method of the subspace set,thus determine almost all weight hierarchies of 5-dimensional linear codes in class IV.It opens the way to determine the weight hierarchies of the rest two of 5-dimensional codes(classes III and VI),and break through the difficulties.Furthermore,the new necessary conditions show that original necessary conditions of the weight hierarchies of k-dimensional codes were not enough(not most tight nor best),so,it is important to excogitate further new necessary conditions for attacking and solving the fc-dimensional problem.展开更多
文摘大熊猫(Ailuropoda melanoleuca)及其生境环境一直受到广泛关注,而主食竹是关系大熊猫生存和发展的关键因素。文章基于中国知网(CNKI)全文数据库和Web of Science核心合集数据库,采用可视化工具VOS viewer和SATI对国内外大熊猫主食竹的相关文献进行计量分析。结果表明国内研究热点主要有关于竹种的分类和分布调查、大熊猫自然保护区的评价等,国外研究热点主要有主食竹的分类学、大熊猫对主食竹的选择性、大熊猫栖息地评价等内容。上述结果揭示了大熊猫主食竹研究的演变特征与发展趋势,有助于加深对该研究领域的整体认识。
文摘大熊猫是一种非常古老而珍贵的濒危物种,与人类相比,大熊猫经历了800万年残酷的生存考验后留存至今。自20世纪80年代以来,关于大熊猫濒临灭绝问题研究日益增多。近10年来全球43个国家的研究者在579种国内外知名杂志刊物上发表学科前端高水平文章,引起世界各国学者对野生大熊猫及其栖息地保护工作的高度重视。本论文主要收集2010—2019年国内外广大学者在大熊猫相关方面研究发表文献,据统计Web of Science引文数据库中1112篇外文文献与中国知网(CNKI)期刊数据库收集到中文核心文献478篇,对这些文章从不同学科领域、发表年份、作者隶属单位、研究内容、期刊影响因子进行分类统计。近3年,大熊猫文献研究深度和文章数量都有明显提高,研究内容不断多元化,多学科科学的研究方向成为其主流。
基金supported by the National Natural Science Foundation of China under Grant No.11171366"the Fundamental Research Funds for the Central Universities"South-Central University for Nationalities under Grant No.CZY12014
文摘The weight hierarchy of a linear[n;k;q]code C over GF(q) is the sequence(d_1,d_2,…,d_k)where d_r is the smallest support of any r-dimensional subcode of C. "Determining all possible weight hierarchies of general linear codes" is a basic theoretical issue and has important scientific significance in communication system.However,it is impossible for g-ary linear codes of dimension k when q and k are slightly larger,then a reasonable formulation of the problem is modified as: "Determine almost all weight hierarchies of general g-ary linear codes of dimension k".In this paper,based on the finite projective geometry method,the authors study g-ary linear codes of dimension 5 in class IV,and find new necessary conditions of their weight hierarchies,and classify their weight hierarchies into6 subclasses.The authors also develop and improve the method of the subspace set,thus determine almost all weight hierarchies of 5-dimensional linear codes in class IV.It opens the way to determine the weight hierarchies of the rest two of 5-dimensional codes(classes III and VI),and break through the difficulties.Furthermore,the new necessary conditions show that original necessary conditions of the weight hierarchies of k-dimensional codes were not enough(not most tight nor best),so,it is important to excogitate further new necessary conditions for attacking and solving the fc-dimensional problem.
