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广西生物多样性受损严重 总被引：3，自引：3，他引：0
受外来物种入侵、人类活动干扰和贫困导致自然资源退化等因素的影响,广西自然生态系统已受到严重破坏。据自治区环保局张英副局长介绍,保护生物多样性已成为当前全世界关注的热点。2005年“国际生物多样性日”的主题是：生物多样性,适应变化世界的生命保障。这一主题充分体现了生物多样性及其生态功能对人类生存和可持续发展的重要支撑作用,也提出了人类如何在全球气候变化、全球经济一体化趋势下保护好地球生命支持系统的问题。 相似文献
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生物多样性保护全球策略首先要求对全球生物多样性热点地区及关键物种生境区采取措施。畜牧种质资源对于人类生存发展具有重要意义，畜牧种质资源的核心产区正是全球生态系统中具有典型代表性和特殊性的地区，同时这些地区也正是人类活动最为频繁地区，已成为生态敏感区，因此这些地区生物多样性保护应该始终成为生物多样性保护的重点地区。目前，这些地区大多在不同程度上比其他地区生态系统遭遇着更为严重地破坏， 相似文献
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植物群落的内禀冗余 总被引：7，自引：5，他引：2
植物落处于各种扰动之中，扰动导致群落的总体功能降低，为适应各种形式的扰动，群落的功能补偿作用就发生了，并由此产生了生长冗余，组分冗余及内颤冗余，内禀冗余是植物群落中组分冗余的一种特殊形式，是对波动的环境及人为或动物扰动适应的结果，是落功能最大化的产物，内禀冗余的作用是使群落多样性，物种多样性得以保持，使群落对各种扰动的抵抗能力增强，在一定条件下，内禀冗余阻碍了群落中当前有益物种产量最大限度地实现，但从生态学观点看，它对植物群落中目标物种的持续较高水平的输出具有重要作用，因此，保留以内禀冗余形式存在的非目标植物种对群落的稳定是有益的。 相似文献
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关注弱势群体、保护弱势群体的合法权益是实现社会公平、全面建设和谐社会的重要任务。笔者从法律的角度对弱势群体的概念进行界定,分析其产生的原因,并在探讨了我国弱势群体法律保护现状的基础上,指出该制度体系存在的问题,提出完善我国弱势群体法律保护制度的建议。 相似文献
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Anthony L Keyburn Ricardo W Portela Kathy Sproat Mark E Ford Trudi L Bannam Xuxia Yan Julian I Rood Robert J Moore 《Veterinary research》2013,44(1):54
NetB toxin from Clostridium perfringens is a major virulence factor in necrotic enteritis in poultry. In this study the efficacy of NetB as a vaccine antigen to protect chickens from necrotic enteritis was examined. Broiler chickens were immunized subcutaneously with purified recombinant NetB (rNetB), formalin treated bacterin and cell free toxoid with or without rNetB supplementation. Intestinal lesion scores and NetB antibody levels were measured to determine protection after mild oral gavage, moderate in-feed and heavy in-feed challenges with virulent C. perfringens isolates. Birds immunized with rNetB were significantly protected against necrotic enteritis when challenged with a mild oral dose of virulent bacteria, but were not protected when a more robust challenge was used. Bacterin and cell free toxoid without rNetB supplementation did not protect birds from moderate and severe in-feed challenge. Only birds immunized with bacterin and cell free toxoid supplemented with rNetB showed significant protection against moderate and severe in-feed challenge, with the later giving the greatest protection. Higher NetB antibody titres were observed in birds immunized with rNetB compared to those vaccinated with bacterin or toxoid, suggesting that the in vitro levels of NetB produced by virulent C. perfringens isolates are too low to induce the development of a strong immune response. These results suggest that vaccination with NetB alone may not be sufficient to protect birds from necrotic enteritis in the field, but that in combination with other cellular or cell-free antigens it can significantly protect chickens from disease. 相似文献
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[Objective] To design a safety device set for fishing vessel net hauler, in order to reduce the severe potential safety hazards in offshore operation. [Method] In view of the operation and structure of net hauler on the fishing trawler, this paper investigated the existing safety protection devices and designed a new set of purely mechanical structure without changing the original structures of the vessel significantly. [Result] Using the easily-adjustable functions of the main shaft of CNC lathe, and simulating the operation performance of different hauling line speeds and testing the safety device, the results showed that the new device could protect the crew from safety accidents caused by net hauler. [Conclusion] The result provides references for the design and application of mechanical protection devices for net haulers on other fishing trawlers. 相似文献
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通过概述世界上东北豹的种群数量特征和分布状况,分析了东北豹保护面临的各种威胁和问题,如人类过度干扰、乱砍滥伐、乱捕滥猎、近亲繁殖以及人类的开发建设等活动对栖息地造成的严重破坏,使栖息地呈片段化、破碎化发展趋势,直接威胁东北豹种群的生存和繁衍。中国对东北豹的保护没有足够的重视,还没有建立专门的东北豹自然保护区,而俄罗斯对于东北豹的保护非常重视,不但建立了专门的东北豹自然保护区,还完善了东北豹的各项保护措施。最后,针对上述情况,提出了东北豹栖息地保护、猎物种群恢复、东北豹的重引入、建立东北豹跨界保护区等相应的保护对策。 相似文献