首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 140 毫秒
1.
面对不断恶化的生态环境,以及日趋枯竭的资源、能源,必须改变不可持续的生产模式.本文基于产业生态学的基本原理,针对我国的环境、资源状况,提出了改变不可持续生产模式的技术方案。  相似文献   

2.
以攀西地区为道地主产区的昆明山海棠(Tripterygium hypoglaucum(Levl.)Hutch)是世界范围内具有极高药用价值的资源植物.我国持续半个世纪的研究相继发现其在众多自身免疫性疾病、肿瘤与白血病、男女计划生育药物以及HIV等方面的重要价值.昆明山海棠已成为世界瞩目的药用植物新星,除我国外,美、日等国均对该植物较为关注并进行研究取得许多重要成果.目前昆明山海棠原料完全依赖野生资源采挖,市场需求增加及野生资源急剧减少,加之自然再生困难,如何保护并发展仅存于我国西南特别是攀西地区的资源,已成为令人关注的问题.本文综述了昆明山海棠历史沿革、药理临床应用及资源再生等方面的研究报道,并就人工引种栽培等方面的进展加以介绍,旨在促进昆明山海棠这种攀西特色药用植物资源的可持续开发利用.  相似文献   

3.
恢复生态学与热带雨林的恢复   总被引:18,自引:0,他引:18  
本文论述恢复生态学的学科内涵、学科发展及其意义。指出恢复生态学的研究对象是那些在自然灾变和人类活动压力条件下受到破坏的自然生态系统的恢复和重建问题,并形成迅速发展的现代生态学的分支学科和世界关注的焦点学科。学科的发展与应用对提高区域生产力、改善生态环境、使资源得以持续利用、经济得以持续发展具有重要的意义。文章进一步对地带性顶极类型的植被的恢复,尤其是对被誉为地球肺部的热带雨林的可恢复性问题进行讨论。  相似文献   

4.
植物形态生长对策研究进展   总被引:7,自引:0,他引:7  
植物在其生长发育的各个阶段的生长行为及生活史策略皆与植物的形态可塑性有很大关系,可在一定程度上决定植物物种在生境中的分布格局及种群行为.植物生活史对策是植物物种维持生长和繁殖的资源最佳分配方式,物种的适应性是物种在进化过程中累积起来的,在形态上有很明显的表现,植物采取不同的形态生长策略就是为了使物种在某些阶段达到最大的适合度.已有的植物形态生长对策研究主要集中在植物繁殖体形态、幼苗形态策略、生长可塑性以及繁殖策略等方面,植物各阶段形态生长策略的权衡以及与植物在群落中的分布关系被认为是今后该方面研究的重要方面.  相似文献   

5.
生态环境退化是指由于人类对自然资源过度以及不合理利用而造成的生态系统结构破坏、功能衰退、生物多样性减少、生物生产力降以及土地生产潜力衰退、土地资源丧失等一系列生态环境恶化的过程和现象,其严重阻碍着社会经济的持续发展,威胁着人类的生存和发展,因此,生态环境退化已引起各国政府和学者的重视。本文初步调查了金沙江干热河谷典型区(无谋段)生态环境退化的特点,认为恶劣的自然条件以及植被破坏、不良耕作、过度放牧等人为干扰是该区生态环境退化的主要原因,生态意识薄弱是生态破坏的重要原因,经济落后是生态环境破坏的最根本原因。在此基础上,探讨了退化生态环境的治理途径。  相似文献   

6.
水生生物栖息地模拟模型是用来描述某一环境对某一特定物种或群落栖息的适宜程度,通过结合物理生境因子时空分布模拟模型和栖息地适宜度评价指标体系,对主要影响特定物种或种群生存、繁殖的栖息环境进行综合影响评价.本文基于栖息地模型发展的历史,总结了水生生物栖息地模型的架构及构建步骤,系统梳理了国内外具有代表性的水生生物栖息地模拟方法及应用情况,并详细阐述了应用较多的几种生境适宜度评价方法,综合分析了栖息地模拟模型的优点和不足,并提出了水生生物栖息地模型未来的发展趋势.  相似文献   

7.
矿山环境问题一直受到国际社会的广泛关注和重视,为了实现资源开采与环境协调一致,实现”低开采、高效率、低排放”目的。本文介绍了矿山开采和利用过程中的矿山环境问题,以及所引起的各种地质灾害现象。分析了资源开采与环境保护之间相互关系以及矿区可持续发展的重要性。针对典型矿山环境破坏问题提出了治理措施,提出了符合21世纪资源开发的全局性矿区”绿色开采”模式。  相似文献   

8.
集约化农业及其环境效应   总被引:4,自引:0,他引:4  
农业集约化通过使用高产农作物品种、化肥、杀虫剂、灌溉以及农业机械化从根本上提高了粮食作物的产量,在一定程度上缓解了我国快速增长的人口与耕地资源相对不足之间的矛盾。由于受到人多地少这一根本性矛盾的制约,集约化经营将是我国农业长期发展的必由之路。然而,受到资源有限性的限制,片面强调有形物质投入的集约化经营是不可取的,它在浪费资源的同时也造成了生态系统中各生物体之间相互作用的改变及资源利用方式的变化,同时也可能对局部的、区域的乃至全球的环境造成严重的影响,其中诸如集约化农区面源污染造成的水污染、土壤和农产品的硝酸盐污染以及土壤板结、生物多样性降低、大气污染等环境问题,需要人们更加审慎地看待集约化农业。  相似文献   

9.
川西箭竹群落生态学研究   总被引:6,自引:0,他引:6  
箭竹是大熊猫的主食竹,主要分布在亚高山地带,是亚高山森林下层重要的优势层片。对箭竹生态学研究主要集中在种群结构、生长、更新、生物生产力、繁殖特性及其在亚高山森林系统水土保持、养分平衡等生态功能发挥中的作用等几方面。而有关箭竹层片对整个森林生态系统养分循环动态过程和机理、箭竹种群生活史动态格局、开花机理、人为干扰下箭竹群落及森林群落更新的过程等方面的研究相对滞后。建议加强箭竹层片在亚高山针叶林生态系统结构和养分循环动态过程中的作用,箭竹克隆生长过程与森林群落更新过程的互动机理、箭竹种群生活史过程中养分源库动态、人为干扰下箭竹克隆种群更新过程与森林更新过程互动等方面的研究。  相似文献   

10.
世界植物园的现状与展望   总被引:12,自引:0,他引:12  
世界植物园的发展史,是一部人类加深认识、进行保护和扩大利用植物的历史。随着植物园数量的增长,植物园可分为综合性、园林和观赏园艺、经济植物及种质保存等类型。当前植物瞻的任务主要为植物多样性的保护、植物资源利用、展示教育与咨询和科学研究。由于植物资源的竞争更加激烈但规范化、管理更加现代化与科学化、植物园更加开放与联合,展望植物园今后的发展,可能将在植物园学和科学植物园、专类园建设及群落建园、植物园信息管理系统、虚拟植物园与科普、植物园网络化、推动植物资源可持续利用等方面不断加强与完善。  相似文献   

11.
一定的自然环境条件孕育着与之相对应的资源利用方式,而不同的资源利用方式常常深刻地影响着不同地区人们的社会、经济、文化活动,同时资源利用方式也常常对少数民族文化的保留和传承产生着重要的影响。此种现象在川西北的民族地区(如阿坝藏族羌族自治州)表现尤为突出。本文通过对藏、羌、回三个不同民族的五个村寨进行的入户调查揭示出这一规律。  相似文献   

12.
The antiviral activity of Shigyaku-to (TJS-109), a traditional Chinese herbal medicine, was investigated in mice infected with herpes simplex virus type 1 (HSV-1). TJS-109 is a combination of the medicinal plant extracts fromZingiberis siccatum rhizoma,Aconiti tuber andGlycyrrhizae radix in a specific proportion. Mice infected with a 10 LD50 dose of HSV-1 were treated with TJS-109 orally at doses of 1.25 to 20 mg/kg 2 days before, and 1 and 4 days after the infection. The treated groups had 80% (1.25 mg/kg), 40% (5 mg/kg) and 23% (20 mg/kg) mortality rates 25 days after the infection as compared with a 100% mortality rate in control mice treated with saline. When HSV-1 infected mice (recipients) received CD8+T cell fractions derived from spleens of mice treated with TJS-109 (donors), 70% of recipients survived, as compared with 0% survivors in the groups of mice treated with saline, B cell fractions, CD4+ T cell fractions or macrophage-enriched fractions prepared from the same donors. TJS-109 did not show any virucidal activities against HSV-1 or any virostatic activities on the growth of HSV-1 in Vero cells. These results suggest that TJS-109 protected mice exposed to lethal amounts of HSV-1 through the activation of CD8+ T cells.  相似文献   

13.
旅游干扰对蒙山植物种类组成的影响   总被引:2,自引:0,他引:2  
2007年7月和2008年7月,采用典型取样法,调查了蒙山旅游区和自然区的植被种类与组成。在旅游区内记录到高等植物161种,其中草本植物99种,灌木40种,乔木22种;在自然区内记录到高等植物201种,其中草本植物117种,灌木57种,乔木27种。蒙山自然区植物群落以麻栎林、赤松林一麻栎林、日本落叶松一麻栎林等落叶林和针阔混交林为主;而蒙山旅游区植物群落以黑松林、油松林、赤松林等针叶林为主。蒙山旅游区植物群落演替滞后于自然区,旅游干扰对5m以外的植被影响明显。建议应继续清查蒙山植物资源,适当降低旅游干扰强度,严格保育自然林,及时清除外来入侵植物。  相似文献   

14.
Phylogeography of crossbills, bullfinches, grosbeaks, and rosefinches   总被引:1,自引:0,他引:1  
Mitochondrial cytochrome b (cyt b) from 24 Carduelini species including crossbills, bullfinches, grosbeaks, rosefinches, and other related, but not conclusively classified species, was sequenced. These sequences were also compared with all the available sequences from the genera Carduelis, Serinus, and Passer. Phylogenetic analyses consistently gave the same groups of finches and the calculated divergence times suggest that speciation of the studied species occurred between 14 and 3 million years ago (Miocene-Pliocene), appearing before the Passer, Carduelis, and Serinus genera. Pleistocene glaciations may have been important in sub-speciation. Crossbills are integrated within the genus Carduelis, and within redpolls; the common crossbill shows subspeciation with Loxia japonica in the Pleistocene epoch. Pinicola enucleator groups together with bullfinches and is probably the ancestor of the group. Hawfinch is only distantly related to the studied groups, and might either represent an isolated genus or be related to the New World genus Hesperiphona. The grosbeak genera Eophona and Mycerobas are clearly sister groups, and species belonging to the former might have given rise to Mycerobas species. The isolated (in classification) Uragus sibiricus and Haematospiza sipahi are included within the genus Carpodacus (rosefinches); Carpodacus nipalensis is outside the genus Carpodacus in the molecular analyses and might be an isolated species or related to the genus Montifringilla.  相似文献   

15.
青藏高原东部暗针叶林采伐迹地小气候及植被演替   总被引:4,自引:0,他引:4  
暗针叶林主要分布在青藏高原东部的多条大江大河的上游和源头地区,具有重要的生态屏障功能,对于维护区域生态安全、促进经济可持续发展具有十分重要的作用。但自20世纪40年代以来,原始林被大规模采伐,形成大面积采伐迹地灌丛和草丛,其生态屏障功能逐步减弱,引起一系列生态环境因子变化。本文综述目前暗针叶林采伐迹地小气候、植被演替的研究现状,指出森林采伐后引起迹地小气候发生剧烈变化,导致迹地植被物种组成、盖度、生物量、生理生态因子等随着人为对其的不同干预也发生着相应的变化。指出今后应加强:(1)暗针叶林采伐迹地植被演替规律的研究;(2)加强人工造林树种的筛选;(3)采伐迹地0~1.5m下垫面小气候立体综合定位监测。  相似文献   

16.
Symmetry principles are commonly said to explain conservation laws—and were so employed even by Lagrange and Hamilton, long before Noether's theorem. But within a Hamiltonian framework, the conservation laws likewise entail the symmetries. Why, then, are symmetries explanatorily prior to conservation laws? I explain how the relation between ordinary (i.e., first-order) laws and the facts they govern (a relation involving counterfactuals) may be reproduced one level higher: as a relation between symmetries and the ordinary laws they govern. In that event, symmetries are meta-laws; they are not mere byproducts of the dynamical and force laws. Symmetries then explain conservation laws whereas conservation laws lack the modal status to explain symmetries. I elaborate the variety of natural necessity that meta-laws would possess. Proposed metaphysical accounts of natural law should aim to accommodate the distinction between meta-laws and mere byproducts of the laws just as they must accommodate the distinction between laws and accidents.  相似文献   

17.
Traditional medicine has been a fertile source for revealing novel lead molecules for modern drug discovery. In plants, terpenoids represent a chemical defense against environmental stress and provide a repair mechanism for wounds and injuries. Interestingly, effective ingredients in several plant-derived medicinal extracts are also terpenoid compounds of monoterpenoid, sesquiterpenoid, diterpenoid, triterpenoid and carotenoid groups. Inflammatory diseases and cancer are typical therapeutic indications of traditional medicines. Thus folk medicine supports the studies which have demonstrated that plant-derived terpenoid ingredients can suppress nuclear factor-κB (NF-κB) signaling, the major regulator in the pathogenesis of inflammatory diseases and cancer.We review the extensive literature on the different types of terpenoid molecules, totalling 43, which have been verified both inhibiting the NF-κB signaling and suppressing the process of inflammation and cancer. It seems that during evolution, plants have established a terpene-based host defense which also represents a cornucopia of effective therapeutic compounds for common human diseases. Received 11 March 2008; received after revision 28 April 2008; accepted 29 April 2008  相似文献   

18.
奥杜藻属(Audouinella)是淡水红藻中一个比较重要的类群,主要特征是:藻体为单列细胞组成的分枝丝体,细胞具数个周生盘状色素体,有时边缘浅裂,无蛋白核,可产生单孢子囊进行无性生殖,具有有性生殖过程。已知的种类全部为淡水产。中国淡水奥杜藻属已报道的种类有10种2变种。利用分子生物学手段对我国淡水奥杜藻属进行深入系统的、多特征的分类研究,将是今后研究的主要发展方向。  相似文献   

19.
近10年来,生物多样性科学的理论和方法取得了显著进展,高度交叉学科-“生物多样性学”孕育而生。但是,诸如生物多样性的生态系统功能、生物多样性与生态系统过程、生物多样性的测度、生物多样性的维持格局与丧失机制等一直是研究的热点和难点,仍在讨论和争论中发展。本文从生物多样性学的理念出发,对生物多样性研究中几个基本问题进行探讨,分析了生物多样性学框架的科学范畴。指出构建以生物多样性保育为核心目标的生物多样性学科体系和框架是生物多样性研究发展的必要。生物多样性学应始终重视实验研究和理论演绎,并不断重视哲学和思维过程。  相似文献   

20.
Are elicitins cryptograms in plant-Oomycete communications?   总被引:13,自引:0,他引:13  
Stimulation of plant natural defenses is an important challenge in phytoprotection prospects. In that context, elicitins, which are small proteins secreted by Phytophthora and Pythium species, have been shown to induce a hypersensitive-like reaction in tobacco plants. Moreover, these plants become resistant to their pathogens, and thus this interaction constitutes an excellent model to investigate the signaling pathways leading to plant resistance. However, most plants are not reactive to elicitins, although they possess the functional signaling pathways involved in tobacco responses to elicitin. The understanding of factors involved in this reactivity is needed to develop agronomic applications. In this review, it is proposed that elicitins could interact with regulating cell wall proteins before they reach the plasma membrane. Consequently, the plant reactivity or nonreactivity status could result from the equilibrium reached during this interaction. The possibility of overexpressing the elicitins directly from genomic DNA in Pichia pastoris allows site-directed mutagenesis experiments and structure/function studies. The recent discovery of the sterol carrier activity of elicitins brings a new insight on their molecular activity. This constitutes a crucial property, since the formation of a sterol-elicitin complex is required to trigger the biological responses of tobacco cells and plants. Only the elicitins loaded with a sterol are able to bind to their plasmalemma receptor, which is assumed to be an allosteric calcium channel. Moreover, Phytophthora and Pythium do not synthesize the sterols required for their growth and their fructification, and elicitins may act as shuttles trapping the sterols from the host plants. Sequence analysis of elicitin genes from several Phytophthora species sheds unexpected light on the phylogenetic relationships among the genus, and suggests that the expression of elicitins is under tight regulatory control. Finally, general involvement of these lipid transfer proteins in the biology of Pythiaceae, and in plant defense responses, is discussed. A possible scheme for the coevolution between Phytophthora and tobacco plants is approached.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号