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981.
982.
生态修复对浮游植物种群结构的影响 总被引:1,自引:0,他引:1
惠州南湖(惠州西湖子湖之一)是典型的亚热带浅水城市湖泊。2007年5月,惠州西湖开展了以水生植被构建和鱼类调控为主的生态系统修复与构建(中试)工程,以控制湖泊富营养化,改善湖泊水质。生态修复后南湖中试区的营养盐含量和富营养化程度有很大的下降.其中TP降低了87.04%,TN下降了64.25%,N:P比由5月份的6.99:1升高到18.32:1。生态修复前浮游植物浮游植物优势种有10种(属)5个门,其中绿藻为优势种群,约占浮游植物总生物量的72.79%。多样性指数为2.03.均匀度为1.095,为富营养化的稳态阶段;生态修复后浮游植物浮游植物优势种有20种(属)6个门,其中隐藻为优势种群,约占总生物量的52.84%,多样性指数为3.58,均匀度为1.113,为清水态型生态系统。生态修复后浮游植物的丰度、生物量以及各种属之间的比例关系发生了较大的变化。通过生态修复工程已经打破了浮游植物的稳态阶段.建立多藻共存的水生态系统.是藻类共存和多样性研究在工程当中一个成功的应用。 相似文献
983.
洋山深水港水域鱼卵仔鱼分布特征 总被引:4,自引:0,他引:4
根据2001年5、8月和2003~2005年间5月和8月分别对洋山港航道水域20个定点测站进行的鱼卵仔鱼调查资料,着重就水域鱼卵仔鱼的数量时空分布和种类组成的年际变化特征与洋山港工程建设产生的环境影响的关系作了分析和探讨.结果表明:鱼卵仔鱼隶属6目19科25种,另有2种未定种.种类数以2005年最高,2004年与2003年持平.2003年和2005年鱼卵仔鱼的种类数比工程前期的2001年有所减少,2004年则与之持平.鱼卵仔鱼的数量年际变化较大,2003年和2005年鱼卵数量均低于2001年,2004年则要高于2001年;仔鱼数量上,2003~2005年均明显低于2001年.从区域分布看,航道区鱼卵仔鱼数量密度最高,其次为港口区,大桥区的数量密度最低.港口航道的开挖建设,其疏浚后海底地形的改变会导致水动力条件的变化而产生泥沙回淤,加上抛泥作业产生的悬浮物对鱼类特别是游泳能力较弱的仔、稚幼鱼会造成不同程度的危害.由于施工造成局部地区的流场和生态有较大改变,使得某些不适应环境变化的亲鱼群体逃离或生殖能力下降,代之以适应能力较强的种群,最终导致优势种群结构的改变较明显.随着工程建设进度的开展,影响程度逐渐趋缓. 相似文献
984.
Reproductive interactions between native and non-native species of fish have received little attention compared to other types of interactions such as predation or competition for food and habitat. We studied the reproductive interactions between non-native brook trout (Salvelinus fontinalis) and native brown trout (Salmo trutta) in a Pyrenees Mountain stream (SW France). We found evidence of significant interspecific interactions owing to consistent spatial and temporal overlap in redd localizations and spawning periods. We observed mixed spawning groups composed of the two species, interspecific subordinate males, and presence of natural hybrids (tiger trout). These reproductive interactions could be detrimental to the reproduction success of both species. Our study shows that non-native species might have detrimental effects on native species via subtle hybridization behavior. 相似文献
985.
One speaks of ecological substitutes when an introduced species performs, to some extent, the ecosystem function of an extirpated native species. We suggest that a similar case exists for habitats. Species evolve within ecosystems, but habitats can be destroyed or modified by natural and human‐made causes. Sometimes habitat alteration forces animals to move to or remain in a suboptimal habitat type. In that case, the habitat is considered a refuge, and the species is called a refugee. Typically refugee species have lower population growth rates than in their original habitats. Human action may lead to the unintended generation of artificial or semiartificial habitat types that functionally resemble the essential features of the original habitat and thus allow a population growth rate of the same magnitude or higher than in the original habitat. We call such areas substitution habitats and define them as human‐made habitats within the focal species range that by chance are partial substitutes for the species’ original habitat. We call species occupying a substitution habitat adopted species. These are 2 new terms in conservation biology. Examples of substitution habitats are dams for European otters, wheat and rice fields for many steppeland and aquatic birds, and urban areas for storks, falcons, and swifts. Although substitution habitats can bring about increased resilience against the agents of global change, the conservation of original habitat types remains a conservation priority. 相似文献
986.
There is increasing concern about the conservation status of sharks. However, the presence of numerous different (and potentially mutually exclusive) policies complicates management implementation and public understanding of the process. We distributed an online survey to members of the largest professional shark and ray research societies to assess member knowledge of and attitudes toward different conservation policies. Questions covered society member opinions on conservation and management policies, personal histories of involvement in advocacy and management, and perceptions of the approach of conservation nongovernmental organizations (NGOs) to shark conservation. One hundred and two surveys were completed (overall response rate 21%). Respondents considered themselves knowledgeable about and actively involved in conservation and management policy; a majority believed scientists have a responsibility to advocate for conservation (75%), and majorities have sent formal public comments to policymakers (54%) and included policy suggestions in their papers (53%). They believe sustainable shark fisheries are possible, are currently happening today (in a few places), and should be the goal instead of banning fisheries. Respondents were generally less supportive of newer limit‐based (i.e., policies that ban exploitation entirely without a species‐specific focus) conservation policy tools, such as shark sanctuaries and bans on the sale of shark fins, than of target‐based fisheries management tools (i.e., policies that allow for sustainable harvest of species whose populations can withstand it), such as fishing quotas. Respondents were generally supportive of environmental NGO efforts to conserve sharks but raised concerns about some NGOs that they perceived as using incorrect information and focusing on the wrong problems. Our results show there is an ongoing debate in shark conservation and management circles relative to environmental policy on target‐based natural resources management tools versus limit‐based conservation tools. They also suggest that closer communication between the scientific and environmental NGO communities may be needed to recognize and reconcile differing values and objectives between these groups. 相似文献
987.
Moreno Di Marco Thomas Brooks Annabelle Cuttelod Lincoln D.C. Fishpool Carlo Rondinini Robert J. Smith Leon Bennun Stuart H.M. Butchart Simon Ferrier Ruud P.B. Foppen Lucas Joppa Diego Juffe‐Bignoli Andrew T. Knight John F. Lamoreux Penny F. Langhammer Ian May Hugh P. Possingham Piero Visconti James E.M. Watson Stephen Woodley 《Conservation biology》2016,30(2):392-402
World governments have committed to increase the global protected areas coverage by 2020, but the effectiveness of this commitment for protecting biodiversity depends on where new protected areas are located. Threshold‐ and complementarity‐based approaches have been independently used to identify important sites for biodiversity. We brought together these approaches by performing a complementarity‐based analysis of irreplaceability in important bird and biodiversity areas (IBAs), which are sites identified using a threshold‐based approach. We determined whether irreplaceability values are higher inside than outside IBAs and whether any observed difference depends on known characteristics of the IBAs. We focused on 3 regions with comprehensive IBA inventories and bird distribution atlases: Australia, southern Africa, and Europe. Irreplaceability values were significantly higher inside than outside IBAs, although differences were much smaller in Europe than elsewhere. Higher irreplaceability values in IBAs were associated with the presence and number of restricted‐range species; number of criteria under which the site was identified; and mean geographic range size of the species for which the site was identified (trigger species). In addition, IBAs were characterized by higher irreplaceability values when using proportional species representation targets, rather than fixed targets. There were broadly comparable results when measuring irreplaceability for trigger species and when considering all bird species, which indicates a good surrogacy effect of the former. Recently, the International Union for Conservation of Nature has convened a consultation to consolidate global standards for the identification of key biodiversity areas (KBAs), building from existing approaches such as IBAs. Our results informed this consultation, and in particular a proposed irreplaceability criterion that will allow the new KBA standard to draw on the strengths of both threshold‐ and complementarity‐based approaches. 相似文献
988.
Quantitative tools for implementing the new definition of significant portion of the range in the U.S. Endangered Species Act 下载免费PDF全文
Julia E. Earl Sam Nicol Ruscena Wiederholt Jay E. Diffendorfer Darius Semmens D. T. Tyler Flockhart Brady J. Mattsson Gary McCracken D. Ryan Norris Wayne E. Thogmartin Laura López‐Hoffman 《Conservation biology》2018,32(1):35-49
In 2014, the Fish and Wildlife Service (FWS) and National Marine Fisheries Service announced a new policy interpretation for the U.S. Endangered Species Act (ESA). According to the act, a species must be listed as threatened or endangered if it is determined to be threatened or endangered in a significant portion of its range (SPR). The 2014 policy seeks to provide consistency by establishing that a portion of the range should be considered significant if the associated individuals’ “removal would cause the entire species to become endangered or threatened.” We reviewed 20 quantitative techniques used to assess whether a portion of a species’ range is significant according to the new guidance. Our assessments are based on the 3R criteria—redundancy (i.e., buffering from catastrophe), resiliency (i.e., ability to withstand stochasticity), and representation (i.e., ability to evolve)—that the FWS uses to determine if a species merits listing. We identified data needs for each quantitative technique and considered which methods could be implemented given the data limitations typical of rare species. We also identified proxies for the 3Rs that may be used with limited data. To assess potential data availability, we evaluated 7 example species by accessing data in their species status assessments, which document all the information used during a listing decision. In all species, an SPR could be evaluated with at least one metric for each of the 3Rs robustly or with substantial assumptions. Resiliency assessments appeared most constrained by limited data, and many species lacked information on connectivity between subpopulations, genetic variation, and spatial variability in vital rates. These data gaps will likely make SPR assessments for species with complex life histories or that cross national boundaries difficult. Although we reviewed techniques for the ESA, other countries require identification of significant areas and could benefit from this research. 相似文献
989.
990.
Zuzanna Magdziak Marek Siwulski Mirosław Mleczek 《Journal of environmental science and health. Part. B》2017,52(10):784-789
The aim of study was to determine 9 organic acids in nine aboveground and seven wood-growing wild edible mushroom species originated from an area under the direct influence of a busy trunk road in Poland. The organic acids in the extracts of samples were identified by reversed-phase column liquid chromatography (RPLC). The presented results show that all the mushroom species were characterized by high variation in the profile and content of the analyzed acids. Each of mushroom species contained oxalic acid, the profiles of the other acids strictly depended on mushroom species. Among aboveground species, the highest total content of organic acids was found in Lepista gilva (267.5 ± 26.6 mg g?1 dry weight (DW)), while Laccaria amethystina was characterized by the lowest content (37.7 ± 6.5 mg g?1 DW). Within wood-growing species, the highest content of organic acids was determined in Flammulina velutipes (171.9 ± 26.7 mg g?1 DW), whereas the lowest content (34.2 ± 2.9 mg g?1 DW) of the studied acids was observed in Grifola frondosa. 相似文献