970 resultados para Camp, C. B.


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稻属(Oryza L.)隶属于禾本科(Gramineae)Ehrhartoideae亚科的稻族(Oryzeae),包括两个栽培种(亚洲栽培稻O. sativa和非洲栽培稻O. glaberrima)和大约20多个野生种,广布于热带亚洲、非洲、大洋洲、中美洲和南美洲。药用野生稻复合体(O. officinalis complex)是稻属中最大、也是最复杂的一个复合体,共包括9个种,含有5种染色体组类型(BCBCCD 和E)。作为栽培稻品质改良的重要基因库,药用野生稻复合体在稻属中具有重要的地位。但是,相似的形态和重叠的地理分布使部分物种的分类和鉴定一直较为困难;种内染色体组构成和倍性的不同更增加了分类鉴定的复杂性。这种情况阻碍了对这些野生稻遗传优势的有效利用。另外,由于物种间断分布和缺乏明确的二倍体亲本等原因,药用野生稻复合体内的异源多倍体起源一直存在争议。本文通过细胞核乙醇脱氢酶基因(Adh)和nrDNA的内转录间隔区(ITS)限制性片段长度多态性(RFLP)分析;叶绿体matK 基因、trnL 内含子和trnL-trnF 基因间隔区、核基因Adh和GPA1以及核糖体DNA ITS片段等序列比较的方法,对药用野生稻复合体中染色体组和物种的鉴定、种间系统发育关系,以及异源多倍体CCDD物种的起源和多倍体ITS的分子进化等进行了研究。主要研究结果如下: 1. 利用核Adh 基因限制性片段长度多态性,检测了来自国际水稻研究所基因库的64份药用野生稻复合体的样品。结果证明,所有O. rhizomatis样品都是含C色体组的二倍体,所有O. minuta样品都是含BC 染色体组的四倍体。但是,种子库中鉴定为O. officinalis、O. punctata和O. eichingeri的样品中,同时都发现了含C色体组的二倍体和含BC染色体组的四倍体。四倍体的O. officinalis只在印度分布,而且曾被描述为另一个种O. malampuzhaensis。 四倍体的O. punctata,也被一些学者称为O. schweinfurthiana,被发现和其二倍体一样分布广泛。值得注意的是,有两个曾被作为O. officinalis 四倍体的样品实际上是含有CD染色体组的物种O. latifolia。我们的结果增进了对国际水稻研究所种子库中部分野生稻样品染色体组构成的理解, 纠正了以往对药用野生稻复合体样品的错误鉴定,为今后进一步研究和利用这部分资源提供了种质编目的重要基础。 2. 对稻属中代表不同地理分布区的、含CD染色体组的11个样品(包括77个克隆)的ITS片段进行了测序。基于这些ITS序列的限制性片段长度多态性,提出一个快速而可靠的区分稻属CD 染色体组物种的方法。这个方法的具体步骤是:(1)利用通用引物扩增ITS 片段;(2)利用限制性内切酶FokI和/或DraⅢ消化PCR扩增产物;(3)用1%的琼脂糖胶电泳并根据消化产物的片段长度多态性来区分不同物种。 3. 利用包括两个叶绿体片段(matK和 trnL-trnF)、nrDNA内转录间隔区(ITS)和三个核基因(Adh1、Adh2和GPA1)的同源序列分析,探讨了药用野生稻复合体中二倍体物种和它们所代表的染色体组之间的系统发育关系。独立和合并的基因系统发育树都显示了一致的结果,即C色体组和B色体组的亲缘关系要比它们和E染色体组的近。三个含C色体组的二倍体中,O. officinalis 和O. rhizomatis表现出较近的亲缘关系。值得注意的是,在O. eichingeri种内,尽管基于多基因的数据支持来自斯里兰卡的样品和来自非洲的样品聚成一个分支,但是较低的支持率表明, 两个地区的样品之间存在着较高的遗传分化。 4. 稻属中含CD染色体组的物种特产于拉丁美洲,包括O. alta、 O. grandiglumis 和O. latifolia。由于具有相同的染色体组类型、相似的形态特征和重叠的地理分布,这3个物种间的系统发育关系一直存在争论。另外,因为美洲大陆上没有含CD染色体组的二倍体物种存在,对这些含CD染色体组物种的可能起源也有不同的假设被提出。使这个问题更具挑战性的是,尽管开展了世界范围的收集,至今仍没有找到含D 染色体组的二倍体物种。在本研究中,代表含CCD和E染色体组以及含G染色体组的外类群共7个物种,共15份样品的2个叶绿体片段(matK和trnL-trnF)和3个核基因(Adh1,Adh2 和 GPA1)部分片段被测序。基于简约法、距离法和最大似然法的系统发育分析都充分支持含CD染色体组的物种起源于一次杂交事件的推论,并且显示,在物种形成时,含C色体组的物种(O. officinalis 或O. rhizomatis 而非O. eichingeri)可能承担了母本,而含E染色体组的物种(O. australiensis)则可能承担了父本。另外,CCDD物种间非常一致的系统发育关系表明,非常大的分歧存在于 O. latifolia 和其它两个种(O. alta和O. grandiglumis)之间,这个结果倾向于将后两个种处理为同种或同种下不同分类群。 5. 基于178个克隆序列比较,探讨了ITS在稻属多倍体中的致同进化及其系统学意义。研究发现稻属异源四倍体的ITS存在不同形式的进化方式:首先,非洲BBCC四倍体O. eichingeri和O. punctata 的ITS片段同时保留了双亲拷贝,而且系统发育研究表明,二倍体的O. eichingeri和O. punctata 可能是这两个四倍体的直接祖先;其次,亚洲四倍体O. malampuzhaensis和O. minuta 的ITS仅定向保留母本ITS拷贝;另外,美洲CCDD四倍体的ITS序列发生了双向致同进化,即O. alta和O. grandiglumis的ITS位点一致化成C色体组类型,而O. latifolia一致化成 D/E 染色体组类型。我们的研究进一步表明在利用ITS片段进行系统发育分析时,特别是涉及异源多倍体时必须慎重。 6. 利用栽培稻的微卫星引物,对含B/C色体组的6个物种,157个体的SSR位点进行扩增。结果在这些亲缘关系稍远的野生稻中得到7个SSR位点,其中5个位点表现出多态性。比较BBCCBBCC物种SSR位点的每位点平均等位基因数A、多态位点百分率P和期望杂合度He ,3项指标发现,四倍体物种的遗传多样性,总体上要高于二倍体物种;二倍体物种内部,O. officnalis的遗传变异最大。另外,以遗传相关性为标准,讨论了B/C色体组物种间的系统发育关系,同时推测了现存二倍体物种和4个BBCC四倍体物种的遗传关系。

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藻胆体在低浓度磷酸缓冲溶液中发生解离,我们通过藻胆体在解离过程中荧光发射光谱的变化研究藻胆体中藻胆蛋白之间的光能传递. 1.发菜(Nostoc flagelliforme)藻胆体在0.9M磷酸缓冲溶液中较稳定,其77K荧光发射光谱中只有一个荧光峰F686,属于别藻蓝蛋白-B荧光峰。当藻胆体在低浓度缓冲溶液中时,荧光峰除了686nm,还出现F648和F666肩,而且F648先于F666肩出现.这说明C-藻蓝蛋白(F'648)所捕获的光能已不能全部传给别藻蓝蛋白-B并说明藻蓝蛋白与别藻蓝蛋白之间的断裂先于别藻蓝蛋白与别藻蓝蛋白-B间的断裂。当进一步解离时,主峰仍位于648nm,次峰位于686nm.而666nm荧光肩消失,说明C-藻蓝蛋白所捕获的光能已不能传给别藻蓝蛋白,但能传给别藻蓝蛋白-B我们因此提出在该藻胆体中藻胆蛋白之间的光能传递途径如下: C藻红蛋白一C-藻蓝蛋白一别藻蓝蛋白_-别藻蓝蛋白-B 在藻胆体的结构方面,我们提出一部分C-藻蓝蛋白与别藻蓝蛋白相连接,另一部分与别藻蓝蛋白-B连接. 2.聚球藻( synechococcus leopoliensis 625)藻胆体在0.6M,0.3M和0.1M磷酸缓冲液中解离时,其77K荧光光谱中只出现别藻蓝蛋白-B(F'684)和C-藻蓝蛋白(F655)的荧光峰消长变化,没有出现别藻蓝蛋白(F666)的荧光,我们为此提出在该藻胆体中光能从C-藻蓝蛋白传给别藻蓝蛋白-B两条途径:一是直接传给别藻蓝蛋白-B另一是传递给别藻蓝蛋白和别藻蓝蛋白-B复合物,此复合物在0.lM到0,6M磷酸缓冲液中比较稳定.即: c-藻红蛋白→c藻蓝蛋白—①别藻蓝蛋白-别藻蓝蛋白-B合物、②别藻蓝蛋白-B

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Algae are the most abundant photosynthetic organisms in marine ecosystems and are essential components of marine food webs. Harmful algal bloom or “HAB species are a small subset of algal species that negatively impact humans or the environment. HABs can pose health hazards for humans or animals through the production of toxins or bioactive compounds. They also can cause deterioration of water quality through the buildup of high biomass, which degrades aesthetic, ecological, and recreational values. Humans and animals can be exposed to marine algal toxins through their food, the water in which they swim, or sea spray. Symptoms from toxin exposure range from neurological impairment to gastrointestinal upset to respiratory irritation, in some cases resulting in severe illness and even death. HABs can also result in lost revenue for coastal economies dependent on seafood harvest or tourism, disruption of subsistence activities, loss of community identity tied to coastal resource use, and disruption of social and cultural practices. Although economic impact assessments to date have been limited in scope, it has been estimated that the economic effects of marine HABs in U.S. communities amount to at least $82 million per year including lost income for fisheries, lost recreational opportunities, decreased business in tourism industries, public health costs of illness, and expenses for monitoring and management. As reviewed in the report, Harmful Algal Research and Response: A Human Dimensions Strategy1, the sociocultural impacts of HABs may be significant, but remain mostly undocumented.

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In 2004, Congress reauthorized the Harmful Algal Bloom and Hypoxia Research and Control Act of 1998 with the Harmful Algal Bloom and Hypoxia Amendments Act (HABHRCA 2004). The 2004 legislation required the generation of five reports, including this "Scientific Assessment of Freshwater Harmful Algal Blooms." HABHRCA 2004 stipulates that this report 1) examine the causes, consequences, and economic costs of freshwater HABs, 2) establish priorities and guidelines for a research program on freshwater HABs, and 3) make recommendations to improve coordination among Federal agencies with respect to research on HABs in freshwater environments. This report is divided into five chapters: Chapter 1 provides the legislative background and process for developing the report, Chapter 2 describes the problem of freshwater and inland HABs in the United States, Chapter 3 outlines the current Federal efforts in freshwater and inland HAB research and response, Chapter 4 discusses the future research priorities, and Chapter 5 delineates opportunities for coordination to advance research efforts. The document is based, in large part, on the proceedings (Hudnell 2008) of the International Symposium on Cyanobacterial Harmful Algal Blooms, a meeting convened by EPA and sponsored by a variety of Federal agencies, to describe current scientific knowledge and identify priorities for future research on CyanoHABs. This report offers a plan for coordinating the important research that is currently ongoing in the United States and for guiding future research directions for Federal programs as well as for state, local, private, and academic institutions in order to maximize advancements. To this end, the Interagency Working Group on Harmful Algal Blooms, Hypoxia, and Human Health (IWG-4H) identifies seven priorities, all of equal weight, for freshwater HAB research and response. These priorities represent research areas where there is the greatest potential for progress in freshwater HAB research. This report does not attempt to assess the relative importance of freshwater HAB research compared to other research areas or other priorities for Federal or state investment.

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This report, "Harmful Algal Bloom Management and Response: Assessment and Plan" reviews and evaluates Harmful Algal Bloom (HAB) management and response efforts, identifies current prevention, control, and mitigation programs for HABs, and presents an innovative research, event response, and infrastructure development plan for advancing the response to HABs. In December 2004, Congress enacted and the President signed into law the Harmful Algal Bloom and Hypoxia Amendments Act of 2004, (HABHRCA 2004). The reauthorization of HABHRCA acknowledged that HABs are one of the most scientifically complex and economically damaging coastal issues challenging our ability to safeguard the health of our Nation’s coastal ecosystems. The Administration further recognized the importance of HABs as a high priority national issue by specifically calling for the implementation of HABHRCA in the President’s U.S. Ocean Action Plan. HABHRCA 2004 requires four reports to assess and recommend research programs on HABs in U.S. waters. This document comprises two linked reports specifically aimed at improving HAB management and response: the Prediction and Response Report and the follow-up plan, the National Scientific Research, Development, Demonstration, and Technology Transfer (RDDTT) Plan on Reducing Impacts from Harmful Algal Blooms. This document was prepared by the Interagency Working Group on Harmful Algal Blooms, Hypoxia, and Human Health, which was chartered through the Joint Subcommittee on Ocean Science and Technology of the National Science and Technology Council and the Interagency Committee on Ocean Science and Resource Management Integration. This report complements and expands upon HAB-related priorities identified in Charting the Course for Ocean Science in the United States for the Next Decade: An Ocean Research Priorities Plan and Implementation Strategy, recently released by the Joint Subcommittee on Ocean Science and Technology. It draws from the contributions of numerous experts and stakeholders from federal, state, and local governments, academia, industry, and non-governmental organizations through direct contributions, previous reports and planning efforts, a public comment period, and a workshop convened to develop strategies for a HAB management and response plan. Given the importance of the Nation’s coastal ocean, estuaries, and inland waters to our quality of life, our culture, and the economy, it is imperative that we move forward to better understand and mitigate the impacts of HABs which threaten all of our coasts and inland waters. This report is an effort to assess the extent of federal, state and local efforts to predict and respond to HAB events and to identify opportunities for charting a way forward.

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Post larval stages of Psettina Iijimae ranging from 1.8 mm NL to 44.6 mm SL collected during Naga Expedition and International Indian Ocean Expedition (IIOE) are described. The characteristics which help to identify larval stages of Psettina are: the presence of pigmented urohyal appendage in early stages which is progressively reduced during flexion stages and which disappears in later postflexion stages, the meristics, the spines on urohyal and posterior basipterygial processes and the absence of spines on cleithra. The P. iijimae can be distinguished by the presence of spines on the median fin rays which differentiate near the baseosts along the dorsal and ventral body wall much before the fin rays. The larvae of P.iijimae were more abundant in the Gulf of Thailand compared to South China Sea and Indian Ocean.

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  氮素作为陆地生态系统生产力主要的限制因子,对生态系统过程的调控有着重要的意义。净氮矿化是有机氮素到无机氮素的转变过程,该过程决定了土壤氮素的可利用性。准确估计土壤的供氮能力可以为确定最佳施肥量和施肥时间提供理论依据,并将影响着土地的可持续发展和管理政策。氮矿化潜力N0被定义为在最适温度和湿度下,土壤氮素在无限时间内所能矿化的最大量。由于氮矿化潜力是土壤供氮能力很好的指示值,所以对氮矿化潜力的研究能够使我们更好地了解土壤的氮素矿化动态和其供氮潜力。   为更好地了解天然草原氮素矿化对全球氮沉降背景以及草原施肥管理模式的响应,我们从2000年起在内蒙古羊草草原开展了长期的氮素添加实验,分别设置对照(N0)、添加5g N•m-2(N1.75)、30g N•m-2(N10.5)和80g N•m-2(N28)四个氮肥添加梯度以及对照(control)、添加100g有机肥•m-2(O100)、添加500g有机肥•m-2(O500)、添加1000g有机肥•m-2(O1000)四个有机肥添加梯度。氮肥添加在相邻并同时进行施肥的两个生态系统类型中展开,即成熟羊草草原(A区,1979年围封)和退化的羊草草原(B,1999年围封),有机肥添加也同时在与之相邻的C中展开(C的土地利用历史与B一致)。 2002年和2006年,从A、B中进行氮肥处理后的土壤取样;有机肥处理的土壤样品从2002年C中获得。土样在最佳温度(25℃)和湿度(60%田间持水量(WHC)下进行了5周室内培养,并用阶段淋溶方法来测定氮肥添加和有机肥添加对土壤氮矿化动态的影响。   氮肥添加显著降低了土壤的pH值,但累积氮矿化量与土壤pH值、有机碳、全氮均没有显著的相关性。在两个区内,氮素添加都显著改变了土壤的累积氮矿化量。最高氮素处理N28相对应于最低的累积氮矿化量,而低氮素处理N1.75却使得累积氮矿化量最高。同时,在N0和N1.75处理中硝态氮的含量高于铵态氮,但在N28处理中却表现出相反趋势。实验还表明大多数氮素添加强度处理在A区比B有更高的土壤累积氮矿化量。   有机肥添加也显著改变了土壤5周内的累积氮矿化量,并且累积氮矿化量随有机肥添加强度的升高而显著增加。培养5周末时土壤的累积铵态氮的含量与有机肥施加强度之间并没有相关性,但是累积硝态氮的含量有随着有机肥施加强度的上升而增加的趋势。   基于前5周土壤培养所得到的结果,我们选择了氮肥添加的N0,N1.75, N28处理以及有机肥添加的control、O100、O1000处理继续进行了长达15周的培养。培养数据与描述土壤氮矿化动态的一级动力学模型--first-order kinetics: Nm=N0(1-exp(-kt))拟合良好( R2=0.893~0.97)。无论是氮肥添加还是有机肥添加都显著增加了土壤的氮矿化潜力N0,并且N0随着氮肥或者机肥添加强度的增加而增加。对于氮肥处理的土壤来说, N0与氮矿化速率常数k之间反向相关,但是在有机氮处理的土壤中N0与k之间却没有相关性。总的结果显示,经有机肥添加的土壤比经氮肥添加的土样有着更大的氮矿化潜力N0值以及氮矿化速率常数k值,较大的k值暗示着土壤氮素较快的周转速率。

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Attempts have been made to correlate the abundance of eggs and larvae of flat fishes belonging to families Cynoglossidae and Soleidae with the hydrographical parameters of the environment, particularly the salinity. The eggs and larvae were found to occur in the Cochin backwater during the pre-monsoon period but not during the south west monsoon period. During the south west monsoon period larvae belonging to very early stages were found at the marine end (Fairway Buoy). The continued or prolonged existence of very low salinity appears to restrict the distribution of flat fish larvae. In the post-monsoon period also the eggs and larvae were not found in regions of very low salinity. Larvae of Cynoglossus puncticeps (Richardson), C. brevis Gunther, C. cynoglossus (Ham. Buch), C. lida (Bleeker) and Solea heinii Steindachner were obtained in the collection taken from the estuary. From the data it is seen that each species has specific spawning period.

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The larvae of bothids were found to be sparsely distributed in the Gulf of Thailand and South China Sea being only 11.9% in the Naga Expedition Collections. They were confined mostly to the coastal waters and were found in near shore stations situated between Bangkok and Saigon. Their density was high in the Gulf of Thailand. The larvae seem to prefer darkness with greater incidence during April 16 to October 15 period, with a peak in the collections taken during April. This report includes the occurrence of 17 species belonging to 6 genera collected from the Gulf of Thailand and South China Sea, along with their regional, seasonal as well as diurnal variations

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本文通过细胞遗传学、mtDNARFLP(线粒体DNA、限制性片段长度多态性)和血液蛋白及同工酶3个方面的研究,分析了云南文山黄牛和迪庆黄牛的遗传多样性和遗传分化关系。结果:(1)细胞遗传学云南两个地方黄牛品种的Y染色体形态及其C带具有显著多态性。文山黄牛和迪庆黄牛分别为一小的近端部和亚申部(或中部)着丝位Y染色体,并分别在Y染色体的臂端部和短臂的臂端部显示弱阳性C带,说明文山黄牛的父系起源可能是瘤牛(Bosindicus),而迪庆黄牛是普遍牛(Bostaurus)。推测两种Y染色体可能是臂问倒位的结果。(2)mtD-NARFLP两个黄牛品种的111个个体的mtDNA经8种限制性内切酶酶切后,有个酶表现出多态,共检测到17种限制性态型。归结出的3种基因单倍型,分别是A-A-A-A-A-A-A型(瘤斗)、BBBBBBB(普通型)和A-CBBCA-A型(耗半Bosgrunniens)。从基因单倍型在群体中的表现可看出,文山黄牛和迪庆黄牛都具有瘤牛和普通牛两种母系起源。但文山黄牛以瘤牛血统为主,迪庆黄牛以普通牛血统为主,而且还可能含有部价耗牛的血统。(3)血液蛋白及同工酶分析了两个黄牛品种的...

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Four-month-old S. niloticus breeders were fed with dry pellets containing 20-50% crude protein and the frequency of spawning involving removal of egg from the mouthbrooding females and growth were determined. When the diets contain high quality proteins from fish meal and soybean oil meal and the amounts of daily food allowance are at satiation level, the influence of increasing dietary crude protein on spawning frequency involving egg removal from the brooder and growth may not be significant.

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本文对三峡水库大坝至香溪河段所设A、BCD、E、F和G等7个站点浮游生物群落DNA进行了RAPD分子生物学研究,并分析了其与水体理化因子的关系。各站点间RAPD研究表明:D和E首先聚到一组,然后与A聚到一起,最后与C成一大类;BF聚成一大类;站点G独自归于一类。而理化因子聚类结果显示:B先与C为一小类,再与D聚到一起,然后与G、F聚成的小类聚为一类,而E与A分别单独归为一类。比较发现,RAPD聚类结果中相距较近的站点在理化因子聚类中显示为相距较远的站点(如站点A、CD、E之间),而在RAPD

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The annealing behavior of Si implanted with Ge and then BF2 has been characterized by double crystal X-ray diffraction (DCXRD) and secondary ion mass spectroscopy (SIMS). The results show that annealing at 600 degrees C for 60 minutes can only remove a little damage induced by implantation and nearly no redistribution of Ge and B atoms has occurred during the annealing. The initial crystallinity of Si is fully recovered after annealing at 950 degrees C for 60 minutes and accompanied by Ge diffusion. Very shallow boron junction depth has been formed. When annealing temperature rises to 1050 degrees C, B diffusion enhances, which leads to a deep diffusion and good distribution of B atoms into the Si substrate. The X-ray diffraction (004) rocking curves from the samples annealed at 1050 degrees C for 60 minutes display two SiGe peaks, which may be related to the B concentration profiles.

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人类对凝聚态物质的亚稳性的认识已经有了相当长的时间。常温常压下,热力学上更不稳定的、而实际上存在的相,都可称之为亚稳相。由于聚合物分子尺寸很大,分子运动的时间尺度具有很宽的范围,因此,在极大多数情况下,聚合物都处于亚稳态下。研究聚合物相行为和相变中的亚稳性,了解并认识亚稳态的存在、演变和终结,对于充分理解高分子凝聚态物理学的基本问题具有极其重要的科学意义,将为高分子材料的加工和功能开发提供新的途径和理论基础。本文正是基于这样一种广义的亚稳性概念,分别研究了聚芳醚酮系列聚合物的形态多样性、物理老化现象和双熔融峰行为以及聚谷氨酸苄酯的超分子组装和构象转变。首先实现了聚醚酮酮的溶液结晶,获得了单晶状片晶,揭示了聚醚酮酮结晶时优先生成片晶的特征。研究了聚醚醚酮酮的物理老化现象,提出了“亚稳刚性非晶相”概念,指出了刚性非晶相中的局部有序性。进一步探索了聚醚醚酮的双熔融峰行为,首次引入“亚稳熔体”概念,解释了亚稳晶体向更稳定晶体的转化。首次应用AFM技术观察到聚谷氨酸苄酯的高有序化组装特征,发现其中存在着侧链苯环间的亚稳性超分子组装结构。应用高分辨核磁共振技术深入研究了聚谷氨酸苄酯在二氯乙烷/二氯乙酸混合溶剂中的构象稳定性,阐明了聚谷氨酸苄酯的构象转变是受慢反应机理控制的,其中质子对分子内氢键的破坏是一个热力学平衡过程,进而揭示了聚谷氨酸苄酯/二氯乙烷/二氯乙酸三元体系的相态稳定性与高分子链构象稳定性的密切相关性,指出聚谷氨酸苄酯存在两种亚稳构象,即无规线团构象和螺旋链构象,这两种亚稳构象的存在决定了聚谷氨酸苄酯/二氯乙烷/二氯乙酸三元体系相态的亚稳性。主要结论如下:1.PEKK(T/I)结晶时优先生成片晶织构。a轴和b位于晶片平面内,c则垂直于晶片平面;b方向为片晶的优先生长方向。从熔融状态等温结晶时,平躺和侧放的片晶相互交错生长构成了辐射状的球晶。从溶液中结晶时既生成“初生态”球晶,也生成单晶状片晶。利用高分辨电镜技术研究了PEKK(T/I)晶体的微区结构。发现PEKK(T/I)晶体中存在许多缺陷,这些缺陷使得品格弯折。2.淬火的PEEKK玻璃态试样处于非平衡状态下,物理老化可引起亚稳玻璃体分子链的局部调整,形成刚性非晶相(Rigid Amorphous Phase)。物理老化时间越长,PEEKK玻璃体中生成的刚性非晶相越多。刚性非晶相中分子链间存在一定的有序性,可以在随后的PEEKK的结晶中起初级晶核的作用,从而降低PEEKK的结晶活化能。3.等温结晶处理的PEEK中分布着两种不同厚度的片晶。这些片晶相互堆砌在一起形成球晶结构。从热力学稳定性和动力学稳定性两方面考虑,这些片晶是亚稳片晶。其中,厚片晶比较稳定,因而在加热至通常的熔融温度前,可稳定存在。但是薄片晶则更不稳定,在加热过程中它要转变成为亚稳熔体;亚稳熔体只能短时存在,它很快就发生重结晶转变为更稳定的晶片。亚稳熔体的结晶过程非常快,它借助样品中已有的厚晶片作为晶核,从厚晶片表面直接向外生长。4.首次应用AFM技术观察到PBLG和PBDG分子的左、右手螺旋结构。揭示了PBLG或PBDG在云母表面上的高度有序化组装。发现PBLG或PBDG分子在云母表面上通过侧向和端基间的相互作用沿着云母表面[100]方向作有组装,进而形成向列相织构。在消旋的PBG共混物中,PBLG侧链上的苯环与PBDG侧链上的苯环之间可以形成规则堆砌结构。这种有序的苯环堆砌结构的形成促成了PBLG与PBDG螺旋分子间的超分子组装。当它们从溶液中析出时可形成纳米级的超分子纤维。5.应用NMR技术研究了PBLG/DCE/DCA三组分体系中PBLG构象的相互转变。在不同的温度下,PBLG可以以无规线团构象或α-螺旋构象存在。无规线团构象和α-螺旋构象在一定的温度范围内可发生相互转变:这种转变并不是受快速的反应过程控制的,而是由非常慢的成核机理控制的一个动力学平衡过程。NMR谱中碳共振双峰和质子共振双峰的出现正是这种动力学平衡的结果。PBLG/DCE/DCA三组分体系从低温到高温分别表现出各相同性态、各相同性与胆甾液晶共存态、胆甾液晶态和高温各相同性态等不同的相态织构。这些相态织构的出现是受PBLG分子的构象决定的。PBLG分子构象表现出强烈的温度依赖性,进而使得PBLG/DCE/DCA三组分体系的相态稳定性也表现出强烈的温度依赖性。

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多相多组分高分子体系的相行为和形态结构一直是高分子科学研究的前沿领域。在这一领域的理论研究中,由于高分子间和高分子链段间相互作用的复杂性,理论结果往往是在一定的近似条件下得到的;另一方面,可用于实验研究的样品总是有限的,而改变体系中分子间的相互作用对实验来说又是极其困难的工作。而计算机模拟却可以避开这些条件的限制。目前计算机模拟不仅仅是实验和理论的补充,人们已经把它看成是"实验"和"理论"以外的第三个分支;由于Monte Carlo模拟能够在分子水平描述模型体系的信息、,进而对高分子体系的相行为和微观结构给出一些符合实际的预测,因而被广泛地应用于物理、数学、化学等一泊一二多领域中。本一沦文主要对二维的多相多组分高分子体系的相行为、形态结构等进行了Monte Carlo模拟研究。我们首先对刀B聚物和均聚物C共混体.系相行为进行了研究,其中链节BC间存在吸引的特殊相互作用。我们的模拟结果表明特殊相互作用的引入可以改善体系的共混相容性。在链二佩声B量较低时,A/B规共聚物和均聚物C共混体系是相分离的,而在链节B含量高于80%时,此共混体系是相容的;当链节B含量较低时,链节B向于分布在共聚物相的界面上;另一方面,链节B含量在O%到80%之间时共聚物的平均末端距小于均聚物的;并且,给出了温度一定时,B量随均聚物组成变化关系的相图。在研究链结构对体系相形态的影响时,我们考虑了A/B替共聚物、无规共聚物和嵌段共聚物分别与均聚物C混合体系,其中,交替共聚物的链节B部集中在均聚物相的界面上;无规共聚物的链节B部分聚集在均聚物相的界面上;而嵌段共聚物更倾向于钻进均聚物聚集的区域。此外,我们研究了A/B嵌段共聚物与均聚物C混体系,在均聚物为连续相的体系中,出现了链段A聚集形成核链段B壳的核壳结构。当链段B含量较低时,共聚物的浓度越高,形成的核越大,核尺寸的分布也越来越宽,当链段B含量很高时,核凡乎不随共聚物浓度的变化而变化。我们还研究了链节A、BC间是都是排斥作用的A/B聚物和均聚物C混体系的形态结构,并考虑了链结构对体系共混相容佩生佩狗影响(我们研究了交替共聚物、无规共聚物和嵌段共聚物三种链结构的共聚物)。随着共聚物分子内的链节A和B间相互作用能的增加,共聚物和均聚物的共混相容性越好;当存在较强的分子内排斥作用时,共聚物的链结构强烈地影响此共混体系的相容性和均聚物的链构象。对于较强的分子内排斥作用的体系,交替共聚物与均聚物的共混相容性最好,并月_形成了相容的体系,其次是无规共聚物和均聚物的共混体系,而嵌段共聚物与均聚物的共混相容性最差;当分子内的相互作用很弱时,共聚物的结构对共聚物与均聚物的共混相容性和均聚物的构象的影响均很刁、。此外,我们对高分子溶液的自组装进行了Monte Car to模拟。在我们的模拟中发现了:州B嵌段共聚物在选择性溶剂中(溶剂是链段B良溶剂)自组装成核壳结构的胶束,且随着高分子溶液浓度的增加,核不断增大。在A一BA三嵌段共聚物溶液体系中,溶剂是链段B良溶剂,是链段A的不良溶剂,此时我们得到了花型结构的胶束,其中花心是由链段A聚集而成,花瓣是由链段B成的,而且在体系中也发现了有些胶束间存在着桥,并且在浓度很高时,体系出现了凝胶现象。此外,我们还研究了由特殊相互作用引起的结构变化。选取A/B段共聚物和A/C规共聚物的溶液体系,其中链节B链节C间存在吸引的特殊相互作用,而链节A与链节BC间都是排斥的,选择性溶剂是链节A的良溶剂,对于链节BC不良溶剂。在此条件刁(,体系形成了核壳结构,其中核主要由链节BC及少量的无规共聚物中的链节A组成。当链节C含量较低时,壳由A/B段共聚物的链段A和A/C规共聚物的部分链节组成,当链节C含量很高时,壳就几乎完全由A/B段共聚物的链段A组成。此外,链节C无规共聚物中的含量强烈影响核的密度极其分布。最后我们对一硬段一软段二嵌段共聚物进行了研究,发现随着硬段在共聚物中含量的增加和硬段的刚性程度的增加,嵌段共聚物更易形成有序结构。本论文中,我们充分考虑了高分子链结构及其分子内和分子间的相互作用对体系形态结构的影响,并且建立了核尺寸、核尺寸'分布、核密度、核密度分布以及平均末端距和平均木端距分布等计算机统计方法。所得到的结果将为高分子多相多组.分体系的相行为和形态结构以及高分子自组装超分子结构材料的研究和设计提供充分依据。