首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   68篇
  免费   5篇
  国内免费   17篇
  2024年   1篇
  2023年   3篇
  2022年   4篇
  2021年   5篇
  2020年   10篇
  2019年   4篇
  2017年   1篇
  2016年   2篇
  2014年   1篇
  2013年   2篇
  2012年   6篇
  2011年   5篇
  2010年   2篇
  2009年   1篇
  2008年   5篇
  2007年   4篇
  2006年   6篇
  2005年   4篇
  2004年   2篇
  2003年   1篇
  2002年   3篇
  2001年   2篇
  2000年   8篇
  1999年   2篇
  1998年   4篇
  1995年   1篇
  1994年   1篇
排序方式: 共有90条查询结果,搜索用时 31 毫秒
31.
We performed a multiyear monitoring study to compare amphibian habitat quality among four natural, four restored, and six created pools. We used successful reproduction and metamorphosis of two vernal pool indicator species, the wood frog and spotted salamander, to represent desired outcomes. Ordination techniques were used to identify the aspects of habitat quality that were most correlated with desired outcomes. Previously published results indicated that pool depth, volume, and hydroperiod were among the best predictors of success, regardless of pool type. Observations in the first few years of monitoring also suggested that pools with longer hydroperiods had a greater abundance of aquatic predators of eggs and larvae of indicator species. This follow‐up study further explores and compares predator–prey relationships among pool types. We quantified within‐pool predator and prey abundance and diversity and collected another year of data on the reproductive success of indicator species. Our results confirmed that mean predator abundance was eight times higher in pools with longer hydroperiods. We documented a 96% decrease in wood frog survival rates in a semi‐permanent, natural pool following a 41% decrease in overhead canopy cover and an increase in green frog abundance. At the same time, wood frog reproductive success increased in nearby restored pools with lower predator abundance. Pools with the highest mean survival rates for the two indicator species combined were short‐ or long‐cycle pools (i.e. hydroperiod of 12–35 weeks) with low predator abundance (i.e. <1 organism L?1) and greater proportions of arthropod prey relative to other food items.  相似文献   
32.
Creationist literature claims that sufficient gaps in morphological continuity exist to classify dinosaurs into several distinct baramins (‘created kinds’). Here, I apply the baraminological method called taxon correlation to test for morphological continuity within and between dinosaurian taxa. The results show enough morphological continuity within Dinosauria to consider most dinosaurs genetically related, even by this creationist standard. A continuous morphological spectrum unites the basal members of Saurischia, Theropoda, Sauropodomorpha, Ornithischia, Thyreophora, Marginocephalia, and Ornithopoda with Nodosauridae and Pachycephalosauria and with the basal ornithodirans Silesaurus and Marasuchus. Morphological gaps in the known fossil record separate only seven groups from the rest of Dinosauria. Those groups are Therizinosauroidea + Oviraptorosauria + Paraves, Tazoudasaurus + Eusauropoda, Ankylosauridae, Stegosauria, Neoceratopsia, basal Hadrosauriformes and Hadrosauridae. Each of these seven groups exhibits within‐group morphological continuity, indicating common descent for all the group’s members, even according to this creationist standard.  相似文献   
33.
马晓菲  石龙宇 《生态学报》2020,40(22):8167-8175
雨洪径流失控引发的负面问题已经影响到城市居民的正常生活。雨水花园作为典型的用于雨洪治理的生态基础设施,是进行城市水管理的重要手段。为提升雨水花园以径流控制为主的生态系统服务能力,研究团队基于物联网技术在中科院城市所内建成一座带有径流控制效益监测系统的雨水花园研究示范样地。景感学作为研究生态系统服务和可持续发展的有效途径,基于其理论分析雨水花园样地这一景感的营造途径、原则、生态系统服务能力,有助于使人-生态基础设施-自然环境三者更和谐地相互融入和适应,进而为雨水花园这类生态基础设施的营造提供借鉴经验。经探究发现雨水花园样地营造遵循了愿景呈现的双向性、方位的顺脉性、营造过程的渐进性三项原则,它可从多方面提供调节服务、支持服务与文化服务,有利于改善区域人居环境。通过径流控制效益监测系统监测、分析得出样地具备显著的调节服务(径流削减)能力,且人们可通过视感、听感、触感感知并享受雨水花园样地供给的文化服务。由于物联网监测技术与居民对各部分生态系统服务的监测和感知能力各有侧重,本研究认为可结合物联网相关监测技术和人的物理感知对雨水花园这类生态基础设施的营造工作进行评估,进而指导这类生态基础设施的建设并提升其生态系统服务能力。  相似文献   
34.
崔宁  于恩逸  吴迪  唐明方  吴钢 《生态学报》2020,40(22):8053-8062
自然保护区是生态建设的核心载体之一,是保护自然生态系统、历史遗迹、自然景观和生物多样性的主要方式,为维护国家生态安全,实现可持续发展提供重要的生态支撑。如何更好的保护自然生态系统、提升生态系统服务、促进区域的和谐发展,实现自然保护区及周边区域的景感营造已成为自然保护区研究的重要内容之一。运用景感生态学的理论和景感营造的理念,规范自然保护区管理范畴,以更好的提升自然生态系统的完整性、系统性和可持续性为目标,从更加满足人们的愿景和社会的需求角度出发,以我国北部典型草原区达里诺尔国家级自然保护区为研究对象,通过景感营造的方法,对其景感生态管理模式进行分析。文章明确了自然保护区景感营造原则,探索其景感营造的实践过程,并借助管理这一载体,把人的愿景和社会的需求与自然保护区的最终发展目标融入管理理念中。通过景感营造这一过程来改善、提升和维持自然保护区所能提供的各项生态系统服务,确保自然保护区在满足人类需求的同时,能够最大限度的、可持续的发挥其功效。  相似文献   
35.
Joseph Hooker first learned that Charles Darwin believed in the transmutation of species in 1844. For the next 14 years, Hooker remained a “nonconsenter” to Darwin’s views, resolving to keep the question of species origin “subservient to Botany instead of Botany to it, as must be the true relation”. Hooker placed particular emphasis on the need for any theory of species origin to support the broad taxonomic delimitation of species, a highly contentious issue. His always provisional support for special creation waned during the 1850s as he lost faith in its expediency for coordinating the study of plant geography, systematics and physiology. In 1858, Hooker embraced Darwin’s “considerable revolution in natural history,” but only after Darwin had carefully molded his transmutationism to meet Hooker’s exacting specifications.  相似文献   
36.
Multiple sequence alignments are successfully applied in many studies for under- standing the structural and functional relations among single nucleic acids and pro- tein sequences as well as whole families. Because of the rapid growth of sequence databases, multiple sequence alignments can often be very large and difficult to visualize and analyze. We offer a new service aimed to visualize and analyze the multiple alignments obtained with different external algorithms, with new features useful for the comparison of the aligned sequences as well as for the creation of a final image of the alignment. The service is named FASMA and is available at http: //bioinformatica.isa.cnr.it /FASMA /.  相似文献   
37.
Macrophyte biomass production and species richness were monitored from 1988 through 1991 in four freshwater wetlands constructed on the floodpain of the Des Plaines River, Lake County, Illinois, USA. The wetlands were constructed in 1988 and pumping of river water began in 1989 under two differentd hydrologic regimes: two wetlands received high water inflow (equivalent to 40 cm wk−1 of water depth) and two received low flow (11 cm wk−1). Biomass production showed no relationship to the hydrologic inflows after two years of experimentation, with both the highest and lowest production occuring in low flow wetlands. Rates of primary production increased between 1990 and 1991 under low flow conditions and decreased under high flow conditions, primarily as a result of the initial composition of the plant community. The change from dry conditions in 1988 to flooded conditions in 1989 altered the species composition in each wetland to include almost 100% wetland-adapted species. Similarity in species composition among the four wetlands diverged from 1988 to 1989 as the plant community adjusted to flooded conditions and then converged in both 1990 and 1991 as the wetlands developed.  相似文献   
38.
Natural experiments have been proposed as a way of complementing manipulative experiments to improve ecological understanding and guide management. There is a pressing need for evidence from such studies to inform a shift to landscape‐scale conservation, including the design of ecological networks. Although this shift has been widely embraced by conservation communities worldwide, the empirical evidence is limited and equivocal, and may be limiting effective conservation. We present principles for well‐designed natural experiments to inform landscape‐scale conservation and outline how they are being applied in the WrEN project, which is studying the effects of 160 years of woodland creation on biodiversity in UK landscapes. We describe the study areas and outline the systematic process used to select suitable historical woodland creation sites based on key site‐ and landscape‐scale variables – including size, age, and proximity to other woodland. We present the results of an analysis to explore variation in these variables across sites to test their suitability as a basis for a natural experiment. Our results confirm that this landscape satisfies the principles we have identified and provides an ideal study system for a long‐term, large‐scale natural experiment to explore how woodland biodiversity is affected by different site and landscape attributes. The WrEN sites are now being surveyed for a wide selection of species that are likely to respond differently to site‐ and landscape‐scale attributes and at different spatial and temporal scales. The results from WrEN will help develop detailed recommendations to guide landscape‐scale conservation, including the design of ecological networks. We also believe that the approach presented demonstrates the wider utility of well‐designed natural experiments to improve our understanding of ecological systems and inform policy and practice.  相似文献   
39.
张国钦  李妍  吝涛  李新虎  王兰  刘文惠 《生态学报》2020,40(22):8130-8140
景感生态学是基于中国传统人居环境营造理论与实践结合现代生态学基本原理形成的新兴学科,注重探讨生态系统服务与可持续发展的关系。可持续发展目标中健康与福祉是其重要内容,因此健康人居环境的营造也是景感生态学的重要应用领域之一。在健康人居环境的营造过程中,健康社区构建具有作为"细胞工程"的基础性作用。因此,从景感生态学的视角探讨健康社区的构建,有助于景感生态学进一步应用于可持续发展与人居环境营造的实践,为健康与福祉的顺利实现提供支撑。从健康社区的定义和主要理念出发,基于健康社区构建的需求本体和供给客体及其相互作用关系,结合生态环境科学的"时-空-量-序"的视角,探讨了生态环境研究应用于健康社区构建的作用及面临的系统性不足、人文性不足和耦合性不足等挑战;进而以景感生态学作为连接生态环境学科与建筑规划学科的纽带,探讨了景感生态学在应对上述挑战中的作用。从景感生态学视角来看,健康社区构建就是将人类健康这一愿景融入到社区健康需求本体与健康供给客体及其相互关系的调控与营造,从而实现社区及人群的健康和可持续发展。健康社区的构建强调社区人群主观健康需求与客观健康供给之间的互动与耦合,与景感生态学强调"景"与"感"相互融合、相互作用具有高度一致性。本文从景感生态学的研究要素、景感营造的理念与研究工具等方面,系统地提出景感生态学视角下的健康社区构建框架:包括融合多景感要素的社区人群健康生态系统服务体系、营造多景感载体的社区人群健康行为意识引导体系和建设多方位的健康社区趋善化管理与智能感知体系。景感生态学所提供的崭新视角和系统性思路,对于健康社区的构建将具有重要的指导作用。  相似文献   
40.
从胚拯救、体细胞杂交、体细胞无性系变异和基因工程4方面综述了现代生物技术在油菜种质创新中所取得的成绩.胚挽救技术主要用于克服远缘杂交受精后的不亲和,提高获得杂种的频率;体细胞杂交由于绕过有性杂交不亲和障碍,扩大了杂交范围;基因工程技术借助分子操作技术,达到定向改变目标生物遗传物质的目的,拓宽其种质资源.另外,对限制生物技术在油菜种质创新中的一些因素和其发展前景进行了讨论.  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