875 resultados para Convention on biological diversity


Relevância:

100.00% 100.00%

Publicador:

Resumo:

存在明显的季节性干旱的实验地的自然生境(无遮荫不补水处理)对于1年生紫茎泽兰来说具有胁迫作用,而对于本地草本植物群落来说,这样的季节性干旱并不存在胁迫作用;在单层遮荫不补水的处理中,紫茎泽兰具有竞争优势,而单层遮荫补水处理对紫茎泽兰的竞争不利。在双层遮荫补水的处理中,紫茎泽兰表现出对本地植物较大的相对竞争优势,但双层覆盖对于二者的生长均构成了较严重的胁迫。 在无覆盖不补水的处理中,紫茎泽兰定居期的死亡率最高,而定居后的生长指标(平均高和平均单株干重)在补水和不补水条件之间没有明显差异;在双层覆盖条件下,紫茎泽兰存活率在补水和不补水条件下,绝对值都较高,而平均单株干重在补水和不补水条件下都比较低;在单层覆盖条件下,紫茎泽兰存活率在补水和不补水条件下都较高,紫茎泽兰的平均高和平均单株干重在不补水处理都显著高于补水处理,而且明显高于其他不覆盖、双层覆盖的补水和不补水处理。说明在实验地的自然生境中,本地群落对紫茎泽兰早期(侵入定居)具有一定的抵抗力,但在这样的生境中的本地植物群落对紫茎泽兰的后期(定居之后)的发展的抵抗力较低;双层覆盖条件(相当于郁闭度高的林下生境)对紫茎泽兰的早期侵入定居虽然抵抗力较差,但是对紫茎泽兰的后期(定居之后)的发展具有较强的抑制作用;单层覆盖条件(相当于受到人畜干扰的郁闭度较低的林下生境)下,本地群落对紫茎泽兰早期侵入定居和后期(定居之后)的发展抵抗力都很低,这一结果提醒我们,紫茎泽兰易于侵入受到过人为干扰的郁闭度较低的林下生境并产生严重危害。 刈割干扰对紫茎泽兰的入侵具有明显的促进作用,高强度刈割的促进作用主要体现在促进紫茎泽兰的个体生长速度和群体生物量上,但低强度刈割的促进作用主要体现在入侵定居的个体数量和群体生物量上。低强度刈割处理中的紫茎泽兰的密度为高强度刈割处理的5倍,单位面积上的紫茎泽兰的生物量最高,达到高强度刈割处理的2.5倍,可见对于紫茎泽兰的入侵而言,低强度的刈割干扰比高强度刈割干扰具有更大的促进作用。 本地植物雀麦、豆科植物、鱼眼草和香薷在与紫茎泽兰混栽后,它们的根际土壤微生物群落结构与紫茎泽兰根际土壤微生物相似性更高,而偏相关分析结果表明,豆科植物和鱼眼草的根际土壤微生物群落结构的变化与它们的生物量生长具有一定的关联性,而对于雀麦和香薷的根际土壤微生物群落结构的变化与它们的生物量生长的关联性不明显,说明紫茎泽兰入侵本地植物群落后可以对生态系统的土壤微生物群落结构造成较大的影响,而微生物的改变并不是对所有的本地植物来说都是非常严峻的。虽然我们实验中的4种本地植物中只有2种本地植物的生长表现出与其根际土壤微生物变化的显著相关性,但这对于本地植物群落已经是非常严重的威胁。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

During the last 4 months of 1982, two research cruises had been carried out at the Sofala Bank by the SRTM "Sevastopolsky Rybak". The authors analyze and compare data on biological characteristics, sexual maturity and localization of Penaeus indicus and Metapenaeus monoceros.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

From November 18th to December 17th 1982, the SRTM "Sebastopolsky Rybak" carried out research cruises on the Sofala Bank in the area between 16°20'S and parallel 19°40'S. The authors analyze data collected on biological characteristics, sexual maturity and localization of Penaeus indicus, Metapenaeus monoceros, Penaeus japonicus, Penaeus monodon and Penaeus latisulcatus.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

文采用蛋白电泳技术研究滇南小耳猪血液蛋白多态性。共分析了滇南小耳猪32个遗传位 点,其中AKP、CAT、ES、PA、6PGD和TF等6个位点检测到多态性,多态位点百分比P=0.1875,平均 杂合度H=0.0712。结果表明滇南小耳猪的血液蛋白多态程度较高,反映在蛋白质水平上的遗传多样 性较为丰富。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The anadromous Chinese sturgeon (Acipenser sinensis), mainly endemic to the Yangtze River in China, is an endangered fish species. The natural population has declined since the Gezhouba Dam blocked its migratory route to the spawning grounds in 1981. In the near future, the completion of the Three Gorges Dam, the world's largest hydroelectric project, may further impact this species by altering the water flow of the Yangtze River. Little is currently known about the population genetic structure of the Chinese sturgeon. In this study, DNA sequence data were determined from the control region (D-loop) of the mitochondrial genome of adult sturgeons (n = 106) that were collected between 1995-2000. The molecular data were used to investigate genetic variation, effective female population size and population history of the Chinese sturgeon in the Yangtze River. Our results indicate that the reduction in abundance did not change genetic variation of the Chinese sturgeon, and that the population underwent an expansion in the past. AMOVA analysis indicated that 98.7% of the genetic variability occurred within each year's spawning populations, the year of collection had little influence on the diversity of annual temporary samples. The relative large effective female population size (N-ef) indicates that good potential exists for the recovery of this species in the future. Strikingly, the ratio of N-ef to the census female population size (N-f) is unusually high (0.77-0.93). This may be the result of a current bottleneck in the population of the Chinese sturgeon that is likely caused by human intervention.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

采用不连续垂直板聚丙烯酰胺凝胶电泳技术,对河曲藏獒、青海藏獒、青海藏狮犬和青海土种犬共4个群体103只犬的9个血液蛋白基因座(Tf、Po、Es-1、Es-2、Sα_2:、Hb、Alb、Pr、Amy)的多态性进行了检测,分析了两个藏獒群体的群体内和群体间的遗传变异,并以Nei氏标准遗传距离(D)为基础用UPGMA法探讨了不同犬群之间的遗传关系.结果表明,在4个被测犬群中,Tf、Po、Es-1、Es-2和Sα_2 5个基因座上存在多态性,其中Tf、Es-1和Po分别由3个等住基因所控制,Es-2和Sα_2,分别由2个等位基因所控制,而Hb、Alb、Pr和Amy基因座均呈现单态;河曲藏獒群体内遗传变异较青海藏獒丰富,而两个藏獒群体间的遗传分化程度很低(G_(ST)=0.0187);以Nei氏标准遗传距离(D)为基础的UPGMA法聚类结果表明.青海藏獒与青海藏狮犬和青海土种犬的遗传关系近于河曲藏獒.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This study describes the current status of the small fish community in Niushan Lake in China, and examines the spatial and seasonal variations of the community in relation to key environmental factors. Based on macrophyte cover conditions, the lake was divided into three major habitat types: (1) Potamogeton maackianus habitat, (2) Potamogeton maackianus and Myriophyllum spicatum habitat, and (3) uncovered or less-covered habitat. Fish were sampled quantitatively in the three habitat types by block nets seasonally from September 2002 to August 2003. A total of 10 469 individuals from 27 fish species were caught, among which 20 species were considered as small fishes. Rhodeus ocellatus, Paracheilognathus imberbis, Pseudorasbora parva, Micropercops swinhonis and Cultrichthys erythropterus were recognized as dominant small fishes according to their abundance and occurrence. It was noted that (1) small fishes predominated the total number of fish species in the lake, which reflected to some degree the size diminution phenomenon of fish resources; (2) many small fishes had plant detritus as their food item, which was consistent with the abundance of macrophyte detritus in the lake and implied the importance of detritus in supporting small fish secondary production. Canonical correspondence analysis suggested that the spatial distributions of most small fishes were associated with complex macrophyte cover conditions. Macrophyte biomass was positively correlated with species richness, diversity index and the catch per unit of effort (CPUE) of the fish community. Water depth had no significant effects on species diversity and distribution of the small fishes. Correspondence analysis revealed a higher occurrence of the small fishes and higher abundance of individuals in summer and autumn. Seasonal length-frequency distributions of several species indicated that more larval and juvenile individuals appeared in spring and summer. This study provides some baseline information which will be essential to long-term monitoring of small fish communities in the Yangtze lakes.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

As observed in nature, complex locomotion can be generated based on an adequate combination of motor primitives. In this context, the paper focused on experiments which result in the development of a quality criterion for the design and analysis of motor primitives. First, the impact of different vocabularies on behavioural diversity, robustness of prelearned behaviours and learning process is elaborated. The experiments are performed with the quadruped robot MiniDog6M for which a running and standing up behaviour is implemented. Further, a reinforcement learning approach based on Q-learning is introduced which is used to select an adequate sequence of motor primitives. © 2006 Springer-Verlag Berlin Heidelberg.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

本文旨在研究氮肥缺失对旱地土壤细菌群落多样性的影响。采用直接提取土壤微生物总DNA的方法,对不施肥(CK)、适量施肥(F1)、和缺氮施肥(F2)3种不同施肥水平土样DNA进行提取,扩增细菌16S rDNA基因片段,建立克隆文库。用限制性内切酶HhaI和RsaI进行PCR-RFLP分析,分别得到146、187、11个酶切类型。采用α多样性的测度对试验结果进行分析统计结果表明,不同处理间土壤细菌的多样性(H′、Ds和Dg)和物种丰富度(dMa、R2和E)均为F1>CK>F2;λ、dMa、E和H′指数在不同施肥处理间的变异系数达到56.96%~163.1%,尤其Simpson指数λ是非常敏感的指标,处理间的差异最大,表明氮肥缺失严重影响土壤细菌群落多样性,合理施肥有利于土壤细菌的多样性。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

通过大田玉米试验,验证新型土壤改良剂对夏玉米生育期土壤水分、紧实度及玉米生理生长特性的影响。结果表明,施用改良剂PJG和PFL夏玉米全生育期平均株高、叶面积分别高于对照20.7%、19.75%和51.88%、72.37%;2种改良剂对干物质积累的影响存在差异,影响效果依次为茎干重>叶干重>根干重。夏玉米光合速率和叶绿素含量受土壤改良剂影响较大,PJG和PFL分别高于对照29.96%、24.48%和73.36%、68.53%。在0~10 cm土层内,施用PJG和PFL后土壤紧实度分别低于对照44.44%和42.91%。施用改良剂PJG后,0~20 cm土层土壤含水量维持在田间持水量的77.9%左右,未施用改良剂土壤,夏玉米生育期表层土壤含水量起伏变化较大。土壤改良剂PJG在夏玉米的施用效果略好于PFL。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

乳酸类聚合物具有广泛的生物学和医学应用潜力,但是乳酸类聚酯主链缺少活性位点限制了其应用的范围。用聚乙二醇与聚乳酸共聚进行改性,可以提高担载水溶性药物的效率和控释能力;氨基酸改性再偶联生物分子可以实现乳酸类聚合物的生物功能化和生物智能化的应用。本论文以功能化乳酸类聚合物为研究对象,按照聚乳酸生物功能由低级到高级的顺序分别考察了乳酸类聚合物作为载药纤维、表面活性材料、蛋白质固载和纯化材料、以及靶向药物载体等在一些生物领域的应用,并获得结果如下:1) 聚乙二醇改性的聚乳酸嵌段共聚物纺丝担载阿霉素,具有体内和体外的长效缓释作用;2)以biotin/PLL—PLA—PEG制备的高分子涂层,具有良好的特异性固载生物分子;3)将biotin/PLL—PLA—PEG与PLGA共混制备生物活性纤维,则特异性的固载蛋白质;4)用聚半胱氨酸改性聚乳酸合成PCys—PLA,再和PLGA共混制备纤维,再表面偶联还原型谷胱甘肽,则可以捕获谷胱甘肽转移酶;5)将folate/PLL—PLA—PEG制备成胶束,则具备了叶酸受体介导的生物智能化靶向送药的功能,尤其是在动物肿瘤模型的试验中表现了良好的叶酸受体靶向性。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

蛇毒C一型凝集素样蛋白一般是由两个相似亚基组成的异构二聚体或由多个异构二聚体组成的多聚体。烙铁头蛇毒血小板活化素TMVA是一个高分子量的C一型凝集素样蛋白。本文研究了烙铁头蛇毒C一型凝聚素样蛋白的生物活性及其作用机制。同时还从烙铁头蛇毒中分离到一个抗凝蛋白(mucroqucetin)。TMVA呈量效关系地诱导P好和洗涤血小板聚集,提示其活化血小板并不调节v从下或不依赖于vWF。抗人血小板糖蛋白(GP)Ib单克隆抗体HIPI呈剂量依赖性特异性抑制TMVA诱导的血小板聚集。抗人GPllb单克隆抗体PZ也抑制血小板聚集。单克隆抗体和流式细胞术分析显示,FITC一TMVA特异性地、剂量依赖性地结合到福尔马林固定的人血小板上,在FIIC-TMVA4O砚浓度时达到饱和性结合状态,这种结合被HIPI特异性地抑制,并呈剂量依赖性。TMVA不结合血小板GPIX、GPllb、GPllla、GPIa、GPlla和GPIV。Mocarhagin仅能部分阻断TMVA诱导的血小板聚集,然而TMVA却能诱导mocarhagin阻断的血小板聚集。以上结果显示TMVA在GPIbQ上的主要受体位于富含亮氨酸第二次重复区氨基酸残基59一81,除此之外,TMVA可能还有其他结合位点。小鼠体内首次给予TMVA后,在短时间内(15min-30min)引起循环血小板数及网织血小板百分率暂时性减低、血小板膜表面P-seleetin的表达暂时性增加,但循环血液中血小板一白细胞复合物未增加;抗鼠血小板单克隆抗体P一selectin、GPllb、GPlll。免疫组化染色显示脾和肺的组织巨噬细胞呈阴性反应,提示TMVA导致循环血小板减少不是巨噬细胞系统对血小板的清除所致。可能是由于TMVA.通过GPIb活化血小板后使P-selectin暴露于胞浆膜表面,这些脱颗粒的血小板在补体的参与下自身溶破,而导致快速的暂时性血小板减少。给予TMVA.后组织病理学显示,肝、脾、肺、肾、胰、大肠及小肠血管未血栓形成;TMVA不影响内源性和外源性凝血系统;TMVA呈剂量依赖性延长小鼠的出血时间,但在TMvA25p眺g时小鼠的出血时间未延长、仍小于5分钟,是一个安全的剂量。以上结果充分证明TMVA具有体内抗血栓作用,血小板自身溶破导致血小板减少在体内抗血栓中可能也起到重要的作用。体内外实验显示TMVA在动物体内外都具有抗补体活性作用。TMVA上调血小板上DAF和CD59的表达,不同程度地上调白细胞上D胚和CDS夕的表达。TMVA在补体系统中的作用可能与其在异种器宫移植中抗IIAR的发生相关。Mucroqucetin是一个由Q链和p链组成的异二聚体蛋白质,其分子量为25KD。。N一末端氨基酸序列与其它该类蛇毒C一型凝集素样蛋白有很高的同源性。Mucroqucetin呈量效关系延长部分凝血活酶时间(APTT),几乎不影响凝血酶原时间(PT)。因子IX和X的抑制试验显示,该纯化蛋白呈量效关系抑制工X因子的凝血活性,不影响X因子,提示mucroqucetin的抗凝活性主要通过结合FIX而实现,是一个血液凝固IX因子结合蛋白。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

本研究以公主岭、沈阳长期试验黑土和棕壤(不施肥、单施化肥、单施有机肥以及有机肥配施化肥)为研究对象。对土壤β-葡糖苷酶、脲酶、酸性(碱性)磷酸单酯酶、芳基硫酸酯酶、脱氢酶和FDA水解酶活性、酶促反应动力学参数、土壤微生物量C和N进行研究,旨在探明不同施肥处理对土壤生物学活性的影响。 结果表明:长期施肥对土壤肥力水平和养分的空间分布均具有显著影响。有机肥配施化肥处理能够显著提高40cm以上土层养分含量。 不同施肥处理对土壤酶活性影响不一致。与不施肥相比,化肥处理对于增强耕层(0~20cm)土壤酶活性效果不显著;有机肥施用后由于向土壤中带入了大量的养分和酶,0~40cm土层土壤酶活性显著增强,尤以有机肥配施化肥处理效果最为显著。剖面中土壤酶活性随土层深度的增加而降低。 土壤微生物量碳、氮和土壤微生物商经长期有机肥处理显著增加。微生物量碳、氮与土壤有机碳、全氮和土壤酶活性之间具有极显著的正相关关系。 长期有机肥或者有机肥配施化肥处理能够提高β-葡糖苷酶、脲酶、酸性磷酸酶、芳基硫酸酯酶的Vmax值和Vmax /Km比值;不同施肥处理对Km值的影响较复杂。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

本文应用重复基因外回纹序列rep-PCR方法直接扩增长日山三种不同赤杨和云南不同地区早冬瓜根瘤内的Frankia菌基因,所获得的REP指纹图谱揭示Frankia菌具有丰富的基因多样性。研究结果表明Frankia菌多样性随地域,海拔,坡问不同而变:多样性指数与自然选抒)玉力大小成正相关:自然选择压力是产生和保持Frankia菌基因多样性的重要因子。同时发现Frankia菌基因型与地域有紧密关系:所观察的云南各地区中,感染高黎贡山旱冬瓜的Frankia菌基因多样性最为丰富。推测与高黎贡山旱冬瓜共生的Frankia可能作为种储备库,为其它地区的寄主植物提供了祖先菌株。在对长白山三种赤杨(东北赤杨,西伯利亚赤杨和色赤杨)根瘤内几百游殆菌基因多样性考察过程中发现,Frankia菌基因类型与寄主赤杨种型关系密切。同时海拔对感染东北赤杨的Frankia菌基因多样性也有一定影响。感染西伯利亚赤杨和色赤杨的Frankia菌享有相同的基因型,可能有较近的亲缘关系。