共查询到20条相似文献，搜索用时 78 毫秒
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1共生固氮的根瘤菌具有共生特异性吗？ 课本上讲述为：“不同的根瘤茵，各自只能侵入特定种类的豆科植物：有的根瘤菌只能侵入一种豆科植物，例如大豆根瘤菌只能侵入大豆的根；有的根瘤菌能够侵入多种豆科植物，例如，蚕豆根瘤菌可以侵入蚕豆、菜豆和豇豆的根。”也就是说共生固氮根瘤菌是具有共生特异性的。那么事实是否如此呢？有关学者通过对收集的根瘤菌分析，得出对根瘤菌与豆科植物共生关系的新认识，即：一种根瘤菌并不是只与一种或几种豆科植物结瘤，在同一生态条件下，很多种植物共生的根瘤菌属同一个种；一种植物不只与一种根瘤菌共生，而是在不同生态条件下与多属种根瘤菌共生固氮。 相似文献
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利用YMA培养基,从新鲜花生根瘤中分离得到黄冈土著花生根瘤菌6株,分别编号为HG-1、HG-2、HG-3、HG-4、HG-5、HG-6。选取黄冈地区广泛使用的3个花生品种(红花1号、红花2号、中花1号)对6个菌株进行盆栽回接实验,结果显示:接种根瘤菌的花生植株都有结瘤,所有菌株均为花生根瘤菌。通过比较根瘤数量和质量,初步筛选出与花生品种红花1号、红花2号、中花1号具有最佳共生固氮匹配关系的根瘤菌菌株分别是HG-5、HG-3、HG-2。 相似文献
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蚕豆根瘤菌的分离及生物学特性研究 总被引：3，自引：0，他引：3
从蚕豆根瘤中分离出了蚕豆根瘤菌，并对其生物学特性进行了研究。结果表明：蚕豆根瘤菌为快生型根瘤菌。该根瘤菌能在NaCl浓度为0．2mol．L^-1的YEM培养基中生长。蚕豆根瘤茵生长的PH值范围为5-10，表现出较强的抗逆性。 相似文献
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邹立基 《四川教育学院学报》1998,(3)
９２年在世界上首次发现丝瓜根瘤,今年１０月份通过了省科委组织的专家验收,查新和专家鉴定结果：在世界上首次发现具有较大经济价值的丝瓜根瘤;找到了分离丝瓜根瘤菌的简便有效方法;在世界上首次找到了解决分离出的非豆科高等植物根瘤菌不结瘤的方法;初步找到了丝瓜根瘤菌剂的独特的工业生产方法。本文仅谈丝瓜根瘤菌结题后的两项研究成果和经济价值。一、固氮菌生产应用研究概况为更好的了解丝瓜根瘤菌的经济价值,首先简要介绍固氮菌生产应用研究概况．１８８３年法国Ｊ、Ｂ．Ｂｏｕｓｉｎｇｇａｕｌｔ发现豆科植物可以固定空气中的… 相似文献
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采用CR-YMA培养基对新鲜的大豆根瘤提取物进行根瘤菌的分离、纯化培养,获菌落为圆形乳白色,表面凸起,直径0.4～0.5cm,革兰反应阴性,显微观察显示为短杆状的根瘤菌26株,并对26个菌株进行蛭石盆栽试验,接种效果显示:接种根瘤菌的大豆植株都有结瘤;与对照相比在结瘤数、鲜瘤重、瘤干重及植株地上部分干重分别增加了14.6%～1330.4%,6.3%～461.9%,28.6%～492.9%,10.2%～86.3%,植株全氮量在9.188%和12.563%之间。初步筛选出与大豆品种"南农1138-2"最佳共生匹配的根瘤菌菌株分别是:AF1、AF9、AH10。 相似文献
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采用野外调查和室内试验法对豫东黄河故道区域豆科植物根瘤菌资源进行调查.采集到根瘤样品72份,包括野生型和栽培型豆科植物共22属29种,根瘤形状主要为球状、棒状、掌状,少数珊瑚状、三棱状、不规则状;颜色多为土黄色、粉色,少数呈白色、绿色、棕色.研究表明,豆科植物结瘤状况及其根瘤特征,除了与宿主遗传特性有关外,还与其生态环境(水分、土壤结构、土壤pH等)有密切关系.抗逆性试验表明,根瘤内生菌对盐碱(NaCl、pH等)具有较强耐受性.该研究为根瘤菌资源的开发和利用提供科学依据. 相似文献
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用百合叶片及其鳞茎叶片离体诱导不定芽 总被引：1，自引：0，他引：1
以MS为基本培养基，附加不同浓度配比的NAA、6-BA、TDZ、2．4-D等激素，分别对5种百合的鳞片叶和叶片进行培养．结果显示，叶片经MS TDZ0．5mg／L和MS 2．4-D0．2mg／L TDZ2．0mg／L诱导可产生不定芽，诱导率最高为20％．MS NAA0．03mg／L、MS NAA0．05mg／L和MS 6-BA2．0mg／L 2．4-D0．2mg／L的培养基都不同程度诱导鳞片叶产生多个不定芽。以MS NAA0．05mg／L芽诱导率最高，不定芽经过继代培养，可长出新鳞茎． 相似文献
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这篇章着重比较分析了榛子的芽和幼茎愈伤组织中紫杉醇的合成能力。用高效液相色谱仪测定榛子，结果显示芽比幼茎含量更高。用2．0mg/L BA和1．4mg/C LNAA诱导幼芽，8天后的愈伤组织以100％的速度感应。较好的培养愈伤组织的方法是用0．5mg/L2，4-D、1．0mg/L NAA和0．5mg/L KT补充B5培养基。测得愈伤组织的生长速度和紫杉醇的含量分别是7．74g／L和0．13％。 相似文献
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罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
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Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
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Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 相似文献
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邱崇丙 《唐山师范学院学报》2014,(1):21-23
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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陈美曦 《山东教育学院学报》2008,23(2):103-107
Different nations have different social cultures, and the social culture of every nation is developing with the development of the nation, language is greatly influenced by social culture, which enables language to possess national and historical characteristics. Word is the smallest, independent, meaningful linguistic unit of language. It can well reflect the national and historical characteristics. From synchronic aspect, the social and cultural influence on word meaning is mainly embodied in conceptual and associative meanings of word. The incorrespondence of word meaning is a phenomenon that exists in both conceptual and associative meanings of word among different languages. From diachronic aspect, the development of social culture causes some changes of word meaning to some extent. Therefore, social culture plays a key role in vocabulary learning and mastery of a language. 相似文献
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Rachel Zupek 《海外英语》2007,(11):40-41
我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了 相似文献
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YANGShiguo 《重庆大学学报(英文版)》2004,3(1):86-88
The problem on the geometrc inequalities involving an n-dimensional simplex and its inscribed simplex is studied. Aninequality is established, which reveals that the difference between the squared circumradius of the n-dimensional simplex andthe squared distance between its circumcenter and barycenter times the squared circumradius of its inscribed simplex is not lessthan the 2(n-1)th power of n times its squared inradius, and is equal to when the simplex is regular and its inscribed siplex is atangent point one. Deduction from this inequality reaches a generalization of n-dimensional Euler inequality indicating that thecircumradius of the simplex is not less than the n-fold inradius. Another inequality is derived to present the relationship betweenthe circumradius of the n-dimensional simplex and the circumradius and inradius of its pedal simplex. 相似文献