共查询到20条相似文献，搜索用时 78 毫秒
1.
表型可塑性是生物变异中由环境引起的一种变异，是植物适应的一种重要方式。对沙参属这样一个形态上复杂多变，分类上很难处理的类群，研究其表型可塑性不仅为探讨性状变异、判断其系统学意义及选择可靠的分类性状提供了有益的资料，而且有助于揭示沙参属植物变异、适应和进化的机制。本文从泡沙参复合体中选择了6个居群，利用播种和移栽试验，通过对不同个体和居群在一致条件下的表现及野外和移栽后的对比，对根、茎、叶，花和果等形态性状的表型可塑性进行了初步的观测分析。结果表明，一些叶片、花部和果实性状具有较大的发育可塑性，尤其是叶形、花萼裂片不仅发育变化大，而且随发育过程定向变化。环境可塑性较大的性状主要是根、茎、花序分枝等性状，而叶片、花部、果实和种子性状的环境饰变能力都较小。最后，对泡沙参复合体形态性状的变异从发育可塑性和环境可塑性的角度进行了讨论。 相似文献
2.
对珍稀特有单种属植物明党参的4个居群的材料,从物种生物学及保护生物学的角度,对它们
的遗传多样性进行了研究和分析。研究结果表明：各居群染色体数目恒定(2n=20),核型类型均为2A型,居群间存在核型多型性,主要表现为染色体的杂合性及随体染色体的位置也有一定变化。采用淀粉凝胶电泳方法,分析了10个酶系统,获得19个基因位点的资料,分析结果表明：居群的遗传变异处于较低水平,多态性位点比率P=33.35％,等位基因平均数A=1.43,等位酶基因多样度指数 Ho：0.03,He=0.07。总的基因位点变异中,有58％的变异来自于居群间,42％的变异存在于居群内,居群杂合体过量的位点仅为13％。偏东部居群的遗传多态性比西南部居群高。根据明党参居群遗传变异式样并结合相关研究,提出了其遗传多样性保护策略。 相似文献
3.
综述分子标记在大麦耐非生物胁迫研究中的应用及其研究进展,包括发育基因效应、野生种或地方种的变异、遗传(QTLs)图谱等。现代引种和育种过程引起物种的遗传变异趋于狭窄、多样性减少,由此可能加重疾病、害虫和非生物胁迫等危害的潜在威胁。发育基因对环境胁迫具有较强的多态性效应;野生大麦和原始地方种为提高耐胁迫性提供了丰富的遗传变异资源。大麦遗传多样性的分离鉴定、遗传图谱构建、及数量性状位点(QTL)分析和分子标记辅助选择,将有助于更好地利用野生种质优良抗性,更有效的选择耐(抗)性基因型。文末从正反两方面简要讨论了分子标记在大麦耐非生物胁迫遗传育种研究中作用。 相似文献
4.
基于生物信息分析的苍术挥发油成分变异及其化学型的划分 总被引：2，自引：0，他引：2
借鉴生物信息学的思路,收集文献报道的数据资料,在分析不同产地问及同一产地不同个体间苍术挥发油变异的基础上,总结苍术种内挥发油变异特点和规律,并使用聚类分析、主成分分析等多变量分析方法探索苍术种内化学型的划分。结果表明,不同产地及同一产地不同个体间苍术挥发油均有很大变异,苍术挥发油组分及含量变异与地理分布有一定相关性,挥发油中6个主要组分含量从南向北方呈现连续递减。苍术挥发油主要呈现两种化学型,一种是以湖北苍术为代表,主要位于湖北、安徽、陕西、河南南部等地,以茅术醇、（-桉油醇为主要组成．不舍或含极微量苍术酮和芹烷二烯酮,简称湖北苍术型（HBA）;另一种主要以江苏茅山为代表,主要位于江苏、山东、河北、河南北部等北方地区,主要有苍术酮、苍术素为主组成,简称茅山苍术型（MA）。 相似文献
5.
本文简要论述了科学研究机构学科分布评价研究的目的和意义.通过对中科院、高校系统化学科研机构学科分布的统计分析,阐明了我国化学基础性研究机构学科分布及力量布局的主要特征,通过对化学国家重点实验室和部门开放实验室学科分布的系统分析,揭示了其与我国中长期化学科学优先发展领域和重点研究领域之间的内在相关性.同时,针对我国化学基础性研究中存在的问题.提出了若干建议. 相似文献
6.
滇东南薄竹山菖蒲塘钨锡多金属矿床位于薄竹山花岗岩体西南侧,矿体主要产于岩体与寒武系地层的接触带,部分产于泥盆系地层构造发育部位,本文在对典型矿体进行地质特征分析的基础上重点进行了围岩蚀变及分带、成矿期次方面的研究,结果表明:矿化强度与不同围岩蚀变类型的叠加呈正相关性,矽卡岩化与矿化关系最为密切,通过横向和纵向的解剖,从岩体到围岩将矽卡岩依次划分为三个带:即钙铝榴石—透辉石化带→透闪石化—绿帘石化带→镁橄榄石化带,进一步查明透闪石化—绿帘石化带为矿化最强烈,可作为找矿标志。通过野外地质调查及显微研究,将矿床划分为四个成矿期:矽卡岩期→石英—硫化物期→碳酸盐—萤石期→表生期,其中矽卡岩期和石英—硫化物期为最重要的成矿期,成矿作用呈现了多阶段的特点。结合岩体地球化学、矿床流体包裹体、同位素示踪及成矿时代等方面的成果,本次工作总结了薄竹山菖蒲塘矿区的钨锡多金属矿床的成矿成因及成矿规律,并初步建立成矿模式。该模式对研究区的找矿突破和潜力评价有重要的指导意义。 相似文献
7.
全球豇豆资源农艺性状多样性分析 总被引：1，自引：0，他引：1
《科技通报》2016,(10)
参照美国农业部标准对来自全球58个国家或地区的768份豇豆资源的17个农艺性状进行了遗传多态性分析。结果显示:整个群体中以白色豆荚和白色、棕眼、光滑、半圆籽粒为主;株叶形态以直立、半蔓生株型及半戟型叶片为主。方差分析显示除粒型、结荚位置、株型及结荚习性在各群体间没有显著差异外,其余性状在各地理群体间显示出一定程度的差异。聚类分析可以在一定程度上区别各地理群,但各地区间(分类界限)不明显。在各群体中,商业栽培品种与其他各地区品种表型区别明显,结荚数和百粒重在各群体中最高,同时变异系数和遗传多样性最低;非洲和亚洲地区资源遗传多样性最高且遗传关系较近;而北美与拉丁美洲地区间群体表型无明显差异,二者与中亚及南亚次大陆地区群体关系更近。因些,推断栽培豇豆由非洲地区起源后,进入亚洲经历了第二次驯化,而后通过殖民扩张进入美洲地区。 相似文献
8.
9.
表观遗传学(epigenetics)是诠释可遗传的基因表达记忆的建立和细胞代间传递的、而并非由DNA排序决定的机制的一门学科。从有着深刻内涵的生物学过程: 生殖, 发育, 老年化和重大疾病着手,解读这一位于基因型和表型之间乃至基因型和环境关联之间信息界面的组构和运营规律是今天生命科学研究的核心内容。以高信息量技术为依托, 以发现(discovery)而非假设(hypothesis)驱动的组学时代的研究模式已赋予传统表观遗传学研究以新的活力。美国已启动的1.9亿美元/5年的表观遗传组学NIH路标图计划和全球筹化中的正常与疾病表观遗传组学计划必将推动表观遗传信号、机制和生物学效应进程的诠释, 继而对生物医学和现代化农业的发展给予有力的推动,同时赋予小科学研究的组学化特征。可以预期,系统全面的表观遗传学研究会对个性化医学、干细胞技术为基础的再生医学、环境医学和优良性状、高产经济物种的培育等关键生物学问题提供解决方案。我们应充分发挥优势, 抓住表观遗传 (组)学中核心的生物学问题, 开展有原始创新并能对国计民生发生巨大影响的科学研究。 相似文献
10.
11.
A research group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol-a chemical found in the skins of red grapes in red wine-can improve the sensitivity of mice to the hormone insulin according to a report in the October issue of Cell Metabolism.…… 《中国科学院院刊(英文版)》2008,22(1):14-15
Aresearch group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol--a chemical found in the skins of red grapes and in red wine--can improve the sensitivity of mice to the hormone insulin, according to a report in the October,2007 issue of Cell Metabolism. As insulin resistance is often characterized as the most critical factor contributing to the development of Type 2 diabetes, the findings“provide a potential new therapeutic approach for preventing or treating” both conditions, the researchers said. 相似文献
12.
Marjorie Armstrong-Stassen Margaret Landstrom Ramona Lumpkin 《The Information Society》1998,14(2):153-164
This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors. 相似文献
13.
Active biological molecules functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery disease diagnosis therapy new nanodevice construction.…… 《中国科学院院刊(英文版)》2008,22(1):22-22
Active biological molecules and functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery, disease diagnosis and therapy, and new nanodevice construction. 相似文献
14.
A joint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology his co-workers from Norway US Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells suggesting that China's projected climate warming could decrease the pest's numbers. The study was published in Proceedings of the National Academy of Sciences on September .…… 《中国科学院院刊(英文版)》2008,22(1):6-7
Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China＇s projected climate warming could decrease the pest＇s numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007. 相似文献
15.
Caroline Haythornthwaite 《The Information Society》2001,17(3):211-226
A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction. 相似文献
16.
《中国科学院院刊(英文版)》2008,22(1):2-3
CAS should stick to the principle of rendering service to, and giving impetus for, the development of China＇s science enterprise by making S＆T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party＇s Leading-member Group at CAS, which was held from 7 to 11 January in Beijing. 相似文献
17.
Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies. 相似文献
18.
《中国科学院院刊(英文版)》2008,22(1)
With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants." 相似文献
19.
Leah A. Lievrouw 《The Information Society》2000,16(2):155-159
This essay focuses on universal service and the Internet as means to support social and political participation. The emphasis on access to telecommunications systems in conventional approaches to universal service is contrasted with access to content. A model of the information environment is described that accounts for the roles of content and conduit, both of which are necessary conditions to achieve true access. A method is outlined for employing information indicators to observe or measure the information environment. 相似文献
20.
Puay Tang 《The Information Society》1998,14(1):19-31
The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means. 相似文献