期刊文献+
共找到558篇文章
< 1 2 28 >
每页显示 20 50 100
Finite family trees of continuous time birth and death processes for evaluating the transmitting speed of information on communication networks
1
作者 马驰 王汉兴 《Journal of Shanghai University(English Edition)》 CAS 2007年第3期237-240,共4页
A finite random graph generated by continuous time birth and death processes with exponentially distributed waiting times was investigated, which is similar to a communication network in daily life. The vertices are t... A finite random graph generated by continuous time birth and death processes with exponentially distributed waiting times was investigated, which is similar to a communication network in daily life. The vertices are the living particles, and directed edges go from mothers to daughters. The size of the communication network was studied. Furthermore, the probability of successfully connecting senders with receivers and the transmitting speed of information were obtained. 展开更多
关键词 birth and death processes family tree random graph communication networks
下载PDF
Family tree and population: Distinction and similarity of the analysis on example of hemophilia
2
作者 Andrey N. Volobuev Peter I. Romanchuk Vladimir K. Malishev 《Natural Science》 2013年第9期979-986,共8页
On the basis of Hardy-Weinberg law the distinction in the philosophy of the description of a family tree and a population is considered. With the help of introduction of the equivalent constant mutagen factor both in ... On the basis of Hardy-Weinberg law the distinction in the philosophy of the description of a family tree and a population is considered. With the help of introduction of the equivalent constant mutagen factor both in a family tree and in a population, the analysis of hemophilia is led. Influence of selection at presence of hemophilia is considered. On the basis of idea of Danforth and Haldane about the balance mutagenesis and selection at presence of hemophilia, the inter-relation of selection parameter and the equivalent constant mutagen factor is found. It is shown, that dynamics of development of hemophilia in a family tree and in population are similar. 展开更多
关键词 Alleles Equivalent Constant MUTAGEN Factor family tree POPULATIon HEMOPHILIA BALANCE of Selection and MUTAGENESIS
下载PDF
Comprehensive annotation of the Chinese tree shrew genome by large-scale RNA sequencing and long-read isoform sequencing 被引量:11
3
作者 Mao-Sen Ye Jin-Yan Zhang +6 位作者 Dan-Dan Yu Min Xu Ling Xu Long-Bao Lv Qi-Yun Zhu Yu Fan Yong-Gang Yao 《Zoological Research》 SCIE CAS CSCD 2021年第6期692-709,共18页
The Chinese tree shrew(Tupaia belangeri chinensis)is emerging as an important experimental animal in multiple fields of biomedical research.Comprehensive reference genome annotation for both mRNA and long non-coding R... The Chinese tree shrew(Tupaia belangeri chinensis)is emerging as an important experimental animal in multiple fields of biomedical research.Comprehensive reference genome annotation for both mRNA and long non-coding RNA(lncRNA)is crucial for developing animal models using this species.In the current study,we collected a total of 234 high-quality RNA sequencing(RNA-seq)datasets and two long-read isoform sequencing(ISO-seq)datasets and improved the annotation of our previously assembled high-quality chromosomelevel tree shrew genome.We obtained a total of 3514 newly annotated coding genes and 50576 lncRNA genes.We also characterized the tissuespecific expression patterns and alternative splicing patterns of mRNAs and lncRNAs and mapped the orthologous relationships among 11 mammalian species using the current annotated genome.We identified 144 tree shrew-specific gene families,including interleukin 6(IL6)and STT3 oligosaccharyltransferase complex catalytic subunit B(STT3B),which underwent significant changes in size.Comparison of the overall expression patterns in tissues and pathways across four species(human,rhesus monkey,tree shrew,and mouse)indicated that tree shrews are more similar to primates than to mice at the tissue-transcriptome level.Notably,the newly annotated purine rich element binding protein A(PURA)gene and the STT3B gene family showed dysregulation upon viral infection.The updated version of the tree shrew genome annotation(KIZ version 3:TS_3.0)is available at http://www.treeshrewdb.org and provides an essential reference for basic and biomedical studies using tree shrew animal models. 展开更多
关键词 tree shrew Genome annotation TRANSCRIPTOME Gene family Virus infection
下载PDF
Ponderosa Pine Seed Source Test in Nebraska in the Central Great Plains of the United States
4
作者 Wayne A. Geyer Keith D. Lynch +1 位作者 Peter Schaefer William R. Lovette 《Open Journal of Forestry》 2013年第3期75-78,共4页
Ponderosa pine (Pinus ponderosa Laws) has been planted widely in the Great Plains for wind breaks. A 1968 study recommended using material from south-central South Dakota and north-central Nebraska. A second test to f... Ponderosa pine (Pinus ponderosa Laws) has been planted widely in the Great Plains for wind breaks. A 1968 study recommended using material from south-central South Dakota and north-central Nebraska. A second test to further delineate seed sources (families) from numerous collection sites in this region was established in 1986. This paper reports results for survival, height, diameter, and D2H (diameter squared X height) measurements at 15 years. Results identify a wide range of suitable families within the region. A majority of the tested sources performed well, thus verifying the original recommendations. 展开更多
关键词 PINUS PonDEROSA PROVENANCE SEED Source family tree Selection Growth Characteristics
下载PDF
Feminine Writings:Between Representations of Past and Present Femininity
5
作者 Priscila Kaufmann Correa 《Psychology Research》 2018年第7期322-334,共13页
The writers of this study are the Countess de Ségur,Louisa May Alcott and Maria Clarice Marinho Villac,from France,the United States and Brazil,respectively.It’s possible to identify a connection in their life t... The writers of this study are the Countess de Ségur,Louisa May Alcott and Maria Clarice Marinho Villac,from France,the United States and Brazil,respectively.It’s possible to identify a connection in their life trajectories―aristocratic and bourgeois families―and the ability to write their books.These publications address a specific audience,composed of children and young people,especially females.The representation of femininity in the narratives is related to the representation of family and religiosity,since it is up to the family to guide the girls in moral terms and this question is quite highlighted by religion.Analyzing the representation of femininity is due to the fact that the main books of female writers bring female protagonists,who exhibit a rebellious and mischievous behavior,which is observed and guided by adults.The representations of femininity is still valued and legitimized.For this reason,the narratives continue to be published and adapted to other languages,bringing to light these representations that remain until the 21st century in new clothing and updated vocabulary.Some adaptations for the Portuguese will also be analyzed,trying to identify longevity the works of these writers and their meaning in some epochs. 展开更多
关键词 feminine writings children’s literature representations of femininity CHILDHOOD family education RELIGIon
下载PDF
Fun Puzzle:Family Tree
6
《疯狂英语(初中天地)》 2015年第5期61-61,共1页
FAMILY TREE Instructions Study the family tree.At the top(on the left and right)of the tree are words for different family relations.Below the tree are some phrases that describe the relationship between the different... FAMILY TREE Instructions Study the family tree.At the top(on the left and right)of the tree are words for different family relations.Below the tree are some phrases that describe the relationship between the different people.Can you put the words in the right boxes? 展开更多
关键词 Fun Puzzle:family tree
下载PDF
Writing Skills Practice:About My Family
7
《疯狂英语(初中天地)》 2016年第12期57-57,共1页
关键词 writing Skills Practice:About My family
下载PDF
Family "Drama" and Self-Empowerment Strategies in the Genealogy Writings of Yuan Jingrong (1786-ca.1852)
8
作者 Binbin Yang 《Frontiers of Literary Studies in China-Selected Publications from Chinese Universities》 2013年第1期37-64,共28页
This article focuses on a genre of late imperial women's writing that has rarely been explored, namely, genealogy writing. By "genealogy writing," I refer not only to family histories composed of lists of descendan... This article focuses on a genre of late imperial women's writing that has rarely been explored, namely, genealogy writing. By "genealogy writing," I refer not only to family histories composed of lists of descendants and ancestors' biographies, but also, more broadly, to writings specifying the terms for ancestral rites. This genre of writing conferred ritual and moral authority, especially during a time when ancestral worship became the defining attribute of a lineage and was held in supreme importance by local families and lineages. Women, however, almost never enjoyed such authority. My selection of the case of Yuan Jingrong (1786-ca.1852, wife to the Vice Minister of Rites, Wu Jie) is based precisely on this concern of genre. By appropriating the authority conferred by genealogy writing, Yuan Jingrong gained the upper hand in her family's dramatic shifts of fortune and power, and pushed women's self-empowering strategies to extraordinary proportions. 展开更多
关键词 genealogy writing Yuan Jingrong ritual and moral authority self-empowering strategies family "drama"
原文传递
Nursery Testing of Superior Tree Progeny of Cupressus funebris
9
作者 谭小梅 周益权 周小舟 《Agricultural Science & Technology》 CAS 2014年第9期1562-1566,共5页
[Objective] Breeding and genetic improvement for Cupressus funebris was performed based on the extensive genetic variation among provenances and fami- lies. [Method] The two-year-old Cupressus funebris, from 4 provena... [Objective] Breeding and genetic improvement for Cupressus funebris was performed based on the extensive genetic variation among provenances and fami- lies. [Method] The two-year-old Cupressus funebris, from 4 provenances and 34 superior Cupressus funebris families introduced from Chongqing and Qiandao Lake of Zhejiang Province, was used as test material, and the differences in growth traits among provenances and families at the seedling stage of Cupressus funebris were investigated. [Result] The height and ground diameter of seedlings differed signifi- cantly among provenances and families. Their variation coefficients among families were 11.37% and 18.89%, and among provenances were 7.25% and 12.58% re- spectively. [Conclusion] There was relatively rich genetic variation in height and ground diameter among provenances and families of Cupressus funebris. It has a certain breeding potential. 展开更多
关键词 Cupressus funebris Superior tree Seedlinq trait family Early selection
下载PDF
dCompaction: Speeding up Compaction of the LSM-Tree via Delayed Compaction 被引量:3
10
作者 Feng-Feng Pan Yin-Liang Yue Jin Xiong 《Journal of Computer Science & Technology》 SCIE EI CSCD 2017年第1期41-54,共14页
Key-value (KV) stores have become a backbone of large-scale applications in today's data centers. Write- optimized data structures like the Log-Structured Merge-tree (LSM-tree) and their variants are widely used ... Key-value (KV) stores have become a backbone of large-scale applications in today's data centers. Write- optimized data structures like the Log-Structured Merge-tree (LSM-tree) and their variants are widely used in KV storage systems like BigTable and RocksDB. Conventional LSM-tree organizes KV items into multiple, successively larger components, and uses compaction to push KV items from one smaller component to another adjacent larger component until the KV items reach the largest component. Unfortunately, current compaction scheme incurs significant write amplification due to repeated KV item reads and writes, and then results in poor throughput. We propose a new compaction scheme, delayed compaction (dCompaction) that decreases write amplification, dCompaction postpones some compactions and gathers them into the following compaction. In this way, it avoids KV item reads and writes during compaction, and consequently improves the throughput of LSM-tree based KV stores. We implement dCompaction on RocksDB, and conduct extensive experiments. Validation using YCSB framework shows that compared with RocksDB, dCompaction has about 40% write performance improvements and also comparable read performance. 展开更多
关键词 key-value store Log-Structured Merge-tree (LSM-tree write amplification delayed compaction
原文传递
一种wandering B+tree问题解决方法 被引量:1
11
作者 杨勇鹏 蒋德钧 《计算机研究与发展》 EI CSCD 北大核心 2023年第3期539-554,共16页
为了应对磁盘和固态硬盘随机写和顺序写性能差异较大的问题,文件系统和块存储系统通常采用日志结构(log-structured)技术将随机写转换为顺序写.因此,对于日志结构存储系统数据和元数据的修改都以异地写的方式执行.在日志结构存储系统中,... 为了应对磁盘和固态硬盘随机写和顺序写性能差异较大的问题,文件系统和块存储系统通常采用日志结构(log-structured)技术将随机写转换为顺序写.因此,对于日志结构存储系统数据和元数据的修改都以异地写的方式执行.在日志结构存储系统中,B+tree常被用于管理元数据,这就会导致wandering B+tree问题,即树结点异地更新会导致树结构递归更新.目前,现有工作主要通过分离树结点的逻辑索引和物理地址,并使用额外的数据结构和物理设备空间存放树结点逻辑索引和物理地址的映射,从而避免递归更新树结构.但现有方法既引入额外空间开销,又存在额外物理设备空间非顺序写的问题.提出IBT B+tree,将树结点逻辑索引和物理地址均存放在树结构中.同时,基于IBT B+tree结构引入dirty链表设计,并提出了非递归更新的IBT B+tree下刷算法.IBT B+tree既解决了wandering B+tree问题,又不引入额外的数据结构和物理设备空间,消除了固定物理设备空间的非顺序写.分别实现IBT B+tree和基于F2FS中NAT设计的B+tree,在此基础上设计实现Monty-Dev块存储系统以评价2棵B+tree.实验表明,在HDD和SSD介质上,IBT B+tree在写放大和下刷效率方面均优于NAT B+tree. 展开更多
关键词 日志结构存储系统 块存储系统 wandering B+tree IBT B+tree 写放大
下载PDF
Activities of some defense proteins associated with age or plant family in larch needles of Larix olgensis and L. kaempferi× L. gmelinii
12
作者 Zhaojun Meng Lili Tong +2 位作者 Lulu Gao Shanchun Yan Yifang Lu 《Journal of Forestry Research》 SCIE CAS CSCD 2017年第1期63-69,共7页
Defence proteins are a kind of chemical defence compounds. They play a key role in plant restraining biotic and abiotic harm. To illuminate activities of some defense proteins associated with age or plant family of la... Defence proteins are a kind of chemical defence compounds. They play a key role in plant restraining biotic and abiotic harm. To illuminate activities of some defense proteins associated with age or plant family of larch, the larch needles were collected from two different families of Korean larch, Larix olgensis and a hybrid larch, L. kaempferi × L. gmelinii, respectively, and then the activities of defence proteins in those were tested using a UV spectrophotometry. The results showed that the activities of protective enzymes at thel6-/17- and 19-year-age groups were higher than those at the other age groups in the both larch species. While the activities of polyphenol oxidase (PPO) at the 16-/17-year-age group and phenylalanine ammonia-lyase (PAL) and protease inhibitors at the 19-year-age group were the highest among all age groups. Then, compared with L. olgensis, the hybrid larch had significant effects on the activities of protective enzymes. The effects of plant family on the activities of PAL and chymotrypsin inhibitor were significantly different, and then those on the activities of PPO were not significantly different. The effects of the two families in L. olgensis on the activities of trypsin inhibitor (TI) were significantly different, while those in the hybrid larch on the activities of TI were contrary. To conclusions showed that the different age and plant family significantly affected the activities of defence proteins in the needles of two larch species, and then enhanced the larch resistance to pests. These could play a key function in forestry tree genetic improvement and management in future. 展开更多
关键词 tree age Chemical defence Defenceprotein LARCH Plant family
下载PDF
一种面向事务型数据库的无锁并发B+tree索引结构
13
作者 李乔 赵鸿昊 +1 位作者 江鹏 张兆心 《高技术通讯》 北大核心 2017年第1期9-19,共11页
为了克服现有多版本并发控制(MVCC)进行数据的并发访问控制中短暂阻塞的缺点,达到读写完全并发,提出了一种基于写时复制的多版本并发B+tree(BCMVBT)索引结构。BCMVBT通过复制分离读写的操作空间以使读写事务在任意时刻完全并发执行,规... 为了克服现有多版本并发控制(MVCC)进行数据的并发访问控制中短暂阻塞的缺点,达到读写完全并发,提出了一种基于写时复制的多版本并发B+tree(BCMVBT)索引结构。BCMVBT通过复制分离读写的操作空间以使读写事务在任意时刻完全并发执行,规避比较与交换(CAS)操作带来的高CPU消耗,达到一写多读场景下的完全并发。同时针对现有多版本开发B+tree(MVBT)范围查询的复杂操作,提出了无锁的BCMVBT的范围查询算法和回收机制,从而实现了索引的插入、查询、更新与回收的无锁并发操作。通过与事务型MVBT(transaction MVBT)的对比,在读写并发环境下BCMVBT的时间消耗降低了50%,实验进一步表明BCMVBT在大事务的场景下具有更高的优势。 展开更多
关键词 事务 索引 B+tree(BT) 多版本并发 写时复制(COW)
下载PDF
Variation in Onko Dialect of Yoruba
14
作者 Gbenga Fakuade Lawal Tope Aminat Adewale Rafiu 《宏观语言学》 2020年第2期64-82,共19页
This paper examined variation in Onko dialect using the family tree model and the corresponding comparative method as the theoretical tool. A wordlist of basic items and a designed frame technique were used to gather ... This paper examined variation in Onko dialect using the family tree model and the corresponding comparative method as the theoretical tool. A wordlist of basic items and a designed frame technique were used to gather data for this study. The data were presented in tables and the analyses were done through descriptive statistics. The data were analyzed to determine variation at the phonological, syntactic and lexical levels. The study revealed differences between Standard Yoruba and Onko dialect as well as the variation therein. Two basic factors discovered to be responsible for variations in Onko are geography(distribution of Onko communities) and language contact. The paper established that Onko exhibits variations, which are however not significant enough to disrupt mutual intelligibility among the speakers, and thus all the varieties remain a single dialect. 展开更多
关键词 VARIATIon onko dialect Yoruba family tree model comparative method TRIANGULATIon
下载PDF
基于更新热点感知的LSM-Tree查询优化
15
作者 林清音 陈志广 《大数据》 2023年第1期126-140,共15页
基于LSM-Tree的键值存储已经得到广泛使用。LSM-Tree通过将更新的数据缓存在内存中、随后批量写入磁盘的优化措施取得极高的写性能。然而,在基于LSM-Tree的键值存储中,被更新键值对的旧数据不会立即从存储系统中清除,导致整个存储系统... 基于LSM-Tree的键值存储已经得到广泛使用。LSM-Tree通过将更新的数据缓存在内存中、随后批量写入磁盘的优化措施取得极高的写性能。然而,在基于LSM-Tree的键值存储中,被更新键值对的旧数据不会立即从存储系统中清除,导致整个存储系统中积累大量的无效数据,最终会显著降低键值存储的读性能。针对以上问题,提出一种更积极的压缩(compaction)方法,通过记录键值对更新的历史信息,识别出更新热点,在整个LSM-Tree存储系统中寻找无效数据大量聚集的SSTable,尽早实施压缩,清除无效数据,缓解写放大效应,从而提升读性能。实验表明,该方法能够降低LevelDB 65.2%的平均读时延、69.4%的99%读尾时延以及71.4%的写放大。 展开更多
关键词 键值存储 日志结构合并树 读性能优化 写放大
下载PDF
东极黑猪群体遗传结构分析及利用
16
作者 黄贺 臧正宇 +5 位作者 王嗣泽 王月月 孟凡伍 张津 郑鹏 赵骞 《东北农业大学学报》 CAS CSCD 北大核心 2024年第1期59-69,共11页
东极黑猪是在我国东北部发现的一种新黑猪群体,试验旨在了解东极黑猪群体结构和遗传多样性,以期更好地保护和利用东极黑猪遗传资源。通过50k SNP芯片研究426头东极黑猪进行遗传多样性、亲缘关系和家系结构,同时加入20头大白猪及20头民... 东极黑猪是在我国东北部发现的一种新黑猪群体,试验旨在了解东极黑猪群体结构和遗传多样性,以期更好地保护和利用东极黑猪遗传资源。通过50k SNP芯片研究426头东极黑猪进行遗传多样性、亲缘关系和家系结构,同时加入20头大白猪及20头民猪数据开展主成分分析(Principal component analysis,PCA)。结果表明,东极黑猪57466个SNPs中有47389个SNPs通过质检;PCA结果显示,3个群体分别聚类,东极黑猪与另外两个猪种区分明显;东极黑猪群体中部分个体遗传关系较近,状态同源(Identity by state,IBS)遗传距离为0.0977~0.3589,平均值为0.2752;连续性纯合片段(Runs of homozygosity,ROH)分析发现该群体平均ROH为317.3 Mb,主要分布在200~300 Mb,群体平均近交系数(FROH)为0.133,说明存在近交情况。根据基因组亲缘关系和聚类分析结果,可将东极黑猪群体分为15个家系。综合分析表明,东极黑猪群体遗传多样性丰富,品种独特,但存在近交,建议引入新血统以防遗传多样性丢失。 展开更多
关键词 东极黑猪 SNP芯片 亲缘关系 近交 家系
下载PDF
露水河沙松优良家系与优良单株初选
17
作者 陆斐 刘刚 +4 位作者 陈晓波 柏景珊 郭郁娇 魏伟 王刚 《北华大学学报(自然科学版)》 CAS 2024年第5期589-596,共8页
以吉林省露水河清水河林场17 a生沙松半同胞子代测定林为研究对象,测定81个参试家系(含1个对照)树高、胸径,调查成活率,估算遗传力,计算各指标变异系数、家系遗传力、遗传增益;采用综合评定法筛选优良家系与优良单株。结果表明:17 a生... 以吉林省露水河清水河林场17 a生沙松半同胞子代测定林为研究对象,测定81个参试家系(含1个对照)树高、胸径,调查成活率,估算遗传力,计算各指标变异系数、家系遗传力、遗传增益;采用综合评定法筛选优良家系与优良单株。结果表明:17 a生沙松平均树高为3.42 m,平均胸径为4.82 cm,平均材积为0.00533 m^(3)。参试家系各测定指标差异均达到极显著水平(P<0.01),家系间树高、胸径、材积和保存率平均变异系数分别为31.39%、51.75%、58.77%、24.02%;树高、胸径、材积家系遗传力和单株遗传力分别为0.545、0.593、0.572和0.232、0.284、0.260。经综合评分排序,按10%入选率筛选出77#、46#、103#、54#、5#、90#、7#、32#等8个优良家系,平均树高、胸径、材积分别为3.85 m、5.93 cm、0.00764 m^(3),分别比对照家系高0.39 m、0.95 cm、0.00184 m^(3),比总平均值高0.43 m、1.11 cm、0.00231 m^(3);优良家系树高、胸径、材积平均遗传增益分别为14.06%、35.33%、49.79%。在优良家系中按10%入选率选择优良单株18株,平均树高、胸径、材积分别为5.15 m、9.69 cm、0.02007 m^(3),分别比对照家系高1.69 m、4.71 cm、0.01427 m^(3),比总平均值高1.73 m、4.87 cm、0.0147 m^(3);优良单株树高、胸径、材积平均遗传增益分别为13.48%、24.69%、33.03%。选出的优良家系与优良单株可为吉林省沙松人工林培育提供育种资源。 展开更多
关键词 沙松 子代测定 优良家系 优良单株
下载PDF
“生命之树”集体叙事实践在安宁疗护患者家庭照顾者中的应用
18
作者 王娟 夏源 +2 位作者 姚玉秀 高璟仪 陈玲 《中国护理管理》 CSCD 北大核心 2024年第6期840-845,共6页
目的:评价“生命之树”集体叙事实践在安宁疗护终末期癌症患者家庭照顾者中的应用效果,为照顾者关怀工作的开展提供实践依据。方法:选取乌鲁木齐市某三级甲等肿瘤专科医院2023年1月—6月接受安宁疗护的终末期癌症患者家庭照顾者76例作... 目的:评价“生命之树”集体叙事实践在安宁疗护终末期癌症患者家庭照顾者中的应用效果,为照顾者关怀工作的开展提供实践依据。方法:选取乌鲁木齐市某三级甲等肿瘤专科医院2023年1月—6月接受安宁疗护的终末期癌症患者家庭照顾者76例作为研究对象,随机分为对照组(n=37)和实验组(n=39)。对照组采用常规入院宣教及心理护理,实验组在对照组的基础上采用“生命之树”集体叙事实践。两组干预前后分别采用预期性悲伤量表、Herth希望量表和生命威胁性疾病家庭照顾者生存质量量表进行调查,评价干预效果。结果:干预后,实验组Herth希望量表和生命威胁性疾病家庭照顾者生存质量量表得分均高于对照组,预期性悲伤量表评分低于对照组,组间比较差异均具有统计学意义(P<0.05)。结论:“生命之树”集体叙事实践可以有效降低家庭照顾者的预期性悲伤,有利于提高家庭照顾者的希望水平及生存质量。 展开更多
关键词 生命之树 集体叙事实践 安宁疗护 家庭照顾者
下载PDF
日本落叶松种子园和人工林优树自由授粉家系苗期选择
19
作者 胡勐鸿 李万峰 +3 位作者 吕寻 戴小芬 李宗德 周卓玲 《森林工程》 北大核心 2024年第6期64-78,共15页
探究日本落叶松种子园和人工林优树自由授粉家系苗期生长性状遗传变异规律,为优良家系造林和后期遗传改良提供参考。以沙坝国家落叶松/云杉良种基地日本落叶松初级无性系种子园25个自由授粉家系和30个人工林优树自由授粉家系为试验材料... 探究日本落叶松种子园和人工林优树自由授粉家系苗期生长性状遗传变异规律,为优良家系造林和后期遗传改良提供参考。以沙坝国家落叶松/云杉良种基地日本落叶松初级无性系种子园25个自由授粉家系和30个人工林优树自由授粉家系为试验材料,种子园混合种子苗作为对照,田间试验采用随机完全区组试验设计,在沙坝国家落叶松云杉良种基地苗木培育圃进行苗期生长试验。数据采用SPSS 16.0进行方差分析、多重比较,并估算遗传力和遗传增益,以2年生苗地径、苗高、新梢生长量为指标,采用Brykin多性状综合评定法进行家系评价和选择。种子园、人工林优树自由授粉家系1年生苗和2年生苗生长性状(地径、苗高、2年生苗新梢生长量)具有丰富的遗传变异,生长性状间具有显著(P<0.05)或极显著(P<0.01)正相关关系,家系选择潜力大。种子园自由授粉家系2年生苗地径、苗高、新梢生长量的表型变异系数分别是27.61%、36.82%、44.28%,家系遗传力依次为0.76、0.79、0.79,人工林优树自由授粉家系地径、苗高、新梢生长量的表型变异系数分别是25.57%、32.94%、38.83%,家系遗传力依次为0.90、0.92、0.92,属较高遗传力。家系生长性状受强的遗传控制,具有一定的稳定遗传能力,家系选择的遗传增益显著。按照50%的入选率初步选择苗期表现好的优良家系,种子园有种1、种25、种8、种34、种26、种12、种16、种20、种2、种100、种7、种21、种101共13个家系入选,入选家系地径、苗高、新梢生长量的遗传增益达到1.89%、6.18%、7.65%;人工林优树自由授粉家系有优19、优8、优2、优28、优30、优3、优7、优1、优18、优6、优15、优26、优25、优24、优13共15个家系入选,入选家系的地径、苗高、新梢生长量的遗传增益分别是3.73%、9.31%、11.19%。不论种子园还是人工林优树自由授粉家系,采用Brykin综合评价法选择的优良家系恰好是将苗高最大的家系入选。因此,建议日本落叶松自由授粉家系苗期采用单一性状——苗高作为评价和选择指标,会更加直观、经济、有效。在50%的入选率下,种子园、人工林优树自由授粉家系苗期分别有13个和15个家系入选,苗期初选家系为造林试验和后期遗传改良提供参考,有效减小田间试验规模,提高选择效率。苗高作为评价和选择指标,在生产中更加直观、方便、实用。 展开更多
关键词 日本落叶松 种子园自由授粉家系 优树自由授粉家系 苗期选择
下载PDF
健康生命轨迹计划缘起与发展:社区-家庭-母婴多层面儿童超重与肥胖干预研究队列
20
作者 范建霞 《临床儿科杂志》 CAS CSCD 北大核心 2024年第9期768-773,共6页
健康生命轨迹计划(HeLTI)是由世界卫生组织(WHO)牵头,中国、加拿大、南非、印度等多个国家参与的前瞻性出生队列干预研究。本项目旨在利用HeLTI在个性化健康教育和权威专业健康指导方面的优势,探索建立涵盖备孕期、孕产期、婴幼儿期、... 健康生命轨迹计划(HeLTI)是由世界卫生组织(WHO)牵头,中国、加拿大、南非、印度等多个国家参与的前瞻性出生队列干预研究。本项目旨在利用HeLTI在个性化健康教育和权威专业健康指导方面的优势,探索建立涵盖备孕期、孕产期、婴幼儿期、学龄前期等多个阶段的社区-家庭-母亲-儿童(CFMC)干预措施,实施连续性多层面的干预,构建国际合作研究平台,实现从生命源头预防肥胖等发育源性疾病的目标。由中国、加拿大共同实施的中加健康生命轨迹计划(SCHeLTI)也称生命树项目,受中国国家自然科学基金委和加拿大卫生研究院共同资助,由国际和平妇幼保健院牵头,与上海交通大学医学院附属新华医院、复旦大学妇产科医院及加拿大舍布鲁克大学等知名大学和机构共同组成研究团队。项目纳入的研究对象主要来自上海市徐汇区、长宁区、闵行区、奉贤区、松江区的妇幼保健院及其管辖的42个社区卫生服务中心。本项目所采用的生命早期多层面综合干预方案将在上海地区乃至全国进行推广,研究结果期待为WHO制定儿童肥胖早期干预指南提供科学依据。 展开更多
关键词 生命树 队列 社区-家庭-母婴干预 儿童肥胖
下载PDF
上一页 1 2 28 下一页 到第
使用帮助 返回顶部