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671.
森林经营主体的碳汇供给潜力差异及影响因素研究 总被引:3,自引:1,他引:2
增加森林碳汇已成为应对气候变化的重要举措。论文基于浙江、江西和福建三省农户和林场的调研数据,以杉木为案例树种,引用生长模型、修正的Faustmann 模型碳密度和价格数据,对单一和碳汇木材复合经营目标下的杉木最佳轮伐期和林地期望值进行了分析,并基于此比较了不同森林经营主体碳汇供给潜力的差异,同时模拟了不同营林成本和利率水平下对森林经营主体碳汇供给差异造成的影响。可以发现,在可能的碳汇林经营模式下,基于目前杉木市场价格远高于碳价格的现实,森林经营主体的经营采伐决策并不会发生明显改变,从而导致在大范围的碳价格变动下碳汇的供给也没有显著增加,这也说明木材收益和碳收益的两个不同经营目标是协调的;林场凭借着规模、技术和资金等资源禀赋优势将成为今后碳汇林的适宜经营和供给主体;从影响因素来看,目前市场利率处于低位徘徊的前提下,即碳汇林地的潜在投资价值巨大,尤其对劣等土地的投资效果明显;理论上营林成本会提升继而导致碳汇供给增加,这反而对于森林固碳有显著正面影响。 相似文献
672.
Species-specific effect of macrobenthic assemblages on meiobenthos and nematode community structure in shallow sandy sediments 总被引:1,自引:0,他引:1
Barbara Urban-Malinga Aleksander Drgas Sławomira Gromisz Natalie Barnes 《Marine Biology》2014,161(1):195-212
Three functionally different macrofaunal species (the filter- and/or surface deposit-feeding polychaete Hediste diversicolor, and the suspension-feeding bivalves Mya arenaria and Cerastoderma glaucum) were introduced as single- and two-species treatments into microcosms containing sandy sediment with a natural meiofaunal community. H. diversicolor is a burrowing species building a system of galleries, C. glaucum lives actively near the sediment surface acting as a biodiffuser and M. arenaria buries deeply and leads a sessile lifestyle. It is shown that H. diversicolor extended the vertical distribution of meiofauna into deeper sediment layers compared to the control and non-Hediste treatments. The response of the nematode community varied significantly among treatments and was dependant on the macrobenthic species composition but not on the species number. Nematode assemblages in all treatments with the polychaete, both in monoculture and with either bivalve, differed significantly from those recorded in other treatments and were more similar than replicates within any other single treatment. H. diversicolor also appeared to have stimulated nematode species diversity. The present study demonstrated that the impact of macrobenthic assemblages on meiofauna is not a simple summation of individual species effects but is species specific. 相似文献
673.
Katherine A. James Jaymie R. Meliker Barbara E. Buttenfield Tim Byers Gary O. Zerbe John E. Hokanson Julie A. Marshall 《Environmental geochemistry and health》2014,36(4):773-782
Consumption of inorganic arsenic in drinking water at high levels has been associated with chronic diseases. Risk is less clear at lower levels of arsenic, in part due to difficulties in estimating exposure. Herein we characterize spatial and temporal variability of arsenic concentrations and develop models for predicting aquifer arsenic concentrations in the San Luis Valley, Colorado, an area of moderately elevated arsenic in groundwater. This study included historical water samples with total arsenic concentrations from 595 unique well locations. A longitudinal analysis established temporal stability in arsenic levels in individual wells. The mean arsenic levels for a random sample of 535 wells were incorporated into five kriging models to predict groundwater arsenic concentrations at any point in time. A separate validation dataset (n = 60 wells) was used to identify the model with strongest predictability. Findings indicate that arsenic concentrations are temporally stable (r = 0.88; 95 % CI 0.83–0.92 for samples collected from the same well 15–25 years apart) and the spatial model created using ordinary kriging best predicted arsenic concentrations (ρ = 0.72 between predicted and observed validation data). These findings illustrate the value of geostatistical modeling of arsenic and suggest the San Luis Valley is a good region for conducting epidemiologic studies of groundwater metals because of the ability to accurately predict variation in groundwater arsenic concentrations. 相似文献
674.
Jiuhui Qu Hongchen Wang Kaijun Wang Gang Yu Bing Ke Han-Qing Yu Hongqiang Ren Xingcan Zheng Ji Li Wen-Wei Li Song Gao Hui Gong 《Frontiers of Environmental Science & Engineering》2019,13(6):88
675.
676.
Jing Peng Ke Wang Xiangbo Yin Xiaoqing Yin Mengfei Du Yingzhi Gao Philip Antwi Nanqi Ren Aijie Wang 《Frontiers of Environmental Science & Engineering》2019,13(6):93
677.
Daniel B. Fitzgerald David R. Smith David C. Culver Daniel Feller Daniel W. Fong Jeff Hajenga Matthew L. Niemiller Daniel C. Nolfi Wil D. Orndorff Barbara Douglas Kelly O. Maloney John A. Young 《Conservation biology》2021,35(5):1627-1638
Many questions relevant to conservation decision-making are characterized by extreme uncertainty due to lack of empirical data and complexity of the underlying ecologic processes, leading to a rapid increase in the use of structured protocols to elicit expert knowledge. Published ecologic applications often employ a modified Delphi method, where experts provide judgments anonymously and mathematical aggregation techniques are used to combine judgments. The Sheffield elicitation framework (SHELF) differs in its behavioral approach to synthesizing individual judgments into a fully specified probability distribution for an unknown quantity. We used the SHELF protocol remotely to assess extinction risk of three subterranean aquatic species that are being considered for listing under the U.S. Endangered Species Act. We provided experts an empirical threat assessment for each known locality over a video conference and recorded judgments on the probability of population persistence over four generations with online submission forms and R-shiny apps available through the SHELF package. Despite large uncertainty for all populations, there were key differences between species’ risk of extirpation based on spatial variation in dominant threats, local land use and management practices, and species’ microhabitat. The resulting probability distributions provided decision makers with a full picture of uncertainty that was consistent with the probabilistic nature of risk assessments. Discussion among experts during SHELF's behavioral aggregation stage clearly documented dominant threats (e.g., development, timber harvest, animal agriculture, and cave visitation) and their interactions with local cave geology and species’ habitat. Our virtual implementation of the SHELF protocol demonstrated the flexibility of the approach for conservation applications operating on budgets and time lines that can limit in-person meetings of geographically dispersed experts. 相似文献
678.
通过探究iNOS/p38 MAPK信号通路在丙烯腈(acrylonitrile,ACN)诱导脑组织损伤中的作用,为进一步研究ACN的神经毒性作用提供依据。选取50只SPF级健康成年雄性SD大鼠,随机分为5组,每组10只。适应性饲养一周后,以12.5、25.0、50.0 mg·kg~(-1)ACN对大鼠进行灌胃染毒,对照组给予玉米油,另设NAC组(300.0 mg·kg~(-1)NAC+50.0 mg·kg~(-1)ACN),1次·天~(-1),6天·周~(-1),共染毒13周。次日称重并处死大鼠,测定大鼠脑组织NO含量、总NOS水平及iNOS、p-p38和p38蛋白表达水平。结果显示,ACN各剂量组大鼠脑组织脏器系数与对照组比较均显著降低(P0.05),高剂量组大鼠脑脏器系数与NAC组比较降低(P0.05)。高剂量组NO含量和总NOS水平显著高于对照组,与NAC组比较,高剂量组NO含量降低(P0.05),总NOS水平升高(P0.05)。Western blot结果显示,ACN高剂量组大鼠脑组织iNOS、p-p38蛋白表达水平和p-p38/p38比值显著高于对照组和NAC组(P0.05)。ACN可激活iNOS/p38MAPK信号通路,这可能是ACN致大鼠脑组织损伤的机制之一。 相似文献
679.
Barbara Carby 《Environmental Hazards》2018,17(3):219-233
It is generally recognised by the disaster risk management and development communities that disasters have a negative impact on development, and indeed can set back development by years. This realisation led to a new paradigm for the management of hazards and their impacts, namely an integrated approach which emphasises disaster risk reduction being incorporated into national development planning. Awareness, however, does not necessarily translate into implementation. ‘Reduce the underlying risk factors’, Priority for Action 4 of The Hyogo Framework for Action 2005–2015, reported the lowest average score for progress of the five priority areas. Challenges to progress, as reported by Governments included inappropriate development practices, high levels of poverty and other factors which increase vulnerability. Various authors have recognised the difficulty of consistently and successfully integrating disaster risk reduction into development planning. This integration is particularly challenging for Small Island Developing States (SIDS) which face high exposure to hazards, vulnerable populations and limited resources, often both human and financial. The efforts of Jamaica, a Caribbean SIDS, at integrating disaster risk reduction into national development, and some factors which proved to be important in making progress are presented here. This retrospective paper is written from the perspective of a participant observer and traces developments in disaster risk management over three decades, 1980–2010. Integration and inclusiveness, use of quantitative methods and application of risk assessments are identified as being important in gaining acceptance for disaster risk reduction. 相似文献
680.
本研究采用普通陶粒、普通陶粒外加静态磁场(50 mT)和磁性陶粒(2.5 mT和5 mT)曝气生物滤池处理高浓度氨氮废水,对比研究了不同类型和强度的磁场强化下曝气生物滤池的硝化反硝化效果,并通过分子生物学手段系统分析了磁场强化硝化反硝化的微生物学机理.结果表明,随着氨氮浓度增加,磁场强化下曝气生物滤池硝化反硝化效果显著高于普通陶粒曝气生物滤池.当氨氮浓度提高到400 mg·L-1时,磁场强化曝气生物滤池(磁性陶粒和外加静态磁场)的氨氮去除率大于97%,高于普通陶粒曝气生物滤池的氨氮去除率(88%);磁场强度为2.5 mT的磁性陶粒曝气生物滤池的总氮去除率达到67%,显著高于其他3个曝气生物滤池(p<0.05)(分别为55%、54%和55%).分子生物学检测结果表明,2.5 mT磁场强度的磁性陶粒上生物膜的硝化反硝化酶活性和功能基因丰度大幅提高,硝化反硝化细菌的丰度及多样性显著增加. 相似文献