全文获取类型
收费全文 | 4034篇 |
免费 | 100篇 |
国内免费 | 53篇 |
专业分类
安全科学 | 250篇 |
废物处理 | 153篇 |
环保管理 | 831篇 |
综合类 | 469篇 |
基础理论 | 1006篇 |
环境理论 | 3篇 |
污染及防治 | 956篇 |
评价与监测 | 312篇 |
社会与环境 | 166篇 |
灾害及防治 | 41篇 |
出版年
2023年 | 31篇 |
2022年 | 41篇 |
2021年 | 46篇 |
2020年 | 57篇 |
2019年 | 70篇 |
2018年 | 85篇 |
2017年 | 123篇 |
2016年 | 140篇 |
2015年 | 109篇 |
2014年 | 134篇 |
2013年 | 351篇 |
2012年 | 185篇 |
2011年 | 236篇 |
2010年 | 182篇 |
2009年 | 203篇 |
2008年 | 210篇 |
2007年 | 221篇 |
2006年 | 205篇 |
2005年 | 178篇 |
2004年 | 156篇 |
2003年 | 138篇 |
2002年 | 136篇 |
2001年 | 97篇 |
2000年 | 69篇 |
1999年 | 63篇 |
1998年 | 48篇 |
1997年 | 64篇 |
1996年 | 50篇 |
1995年 | 54篇 |
1994年 | 56篇 |
1993年 | 46篇 |
1992年 | 39篇 |
1991年 | 31篇 |
1990年 | 29篇 |
1989年 | 27篇 |
1988年 | 23篇 |
1987年 | 17篇 |
1986年 | 17篇 |
1985年 | 23篇 |
1984年 | 18篇 |
1983年 | 28篇 |
1982年 | 22篇 |
1981年 | 32篇 |
1980年 | 19篇 |
1979年 | 18篇 |
1978年 | 13篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1969年 | 4篇 |
排序方式: 共有4187条查询结果,搜索用时 46 毫秒
971.
972.
Michael Sivak 《Journal of Safety Research》1983,14(3):93-99
This research investigated the relationship of violence/aggression and other societal variables to traffic accidents. In the first of two studies, multiple regression was applied to 1977 data from each of the 50 states and the District of Columbia. Traffic fatalities per registered vehicle was the dependent variable. The independent variables were homicide rate, suicide rate, fatality rate from other causes, unemployment rate, personal income, density of physicians, alcohol consumption, motor vehicles per capita, road mileage per vehicle, sex and age distribution of drivers, and attained education. The main finding was that the homicide rate (but not the suicide rate) predicted the traffic fatality rate; additional significant predictors were the proportion of young drivers and the fatality rate from non-motor-vehicle accidents. The two primary predictors (homicides and young drivers) accounted for 64 % of the variance of traffic fatalities. In the second study, validation was performed by using the 1977 regression coefficients to estimate 1978 traffic fatalities. The results indicate that when the 1977 regression coefficients were applied to the 1978 values for homicides and young drivers, they accounted for 49 % of the variance of the 1978 traffic fatalities. The findings are discussed in terms of how society's violence/aggression may contribute to traffic accidents. 相似文献
973.
Michael J. Polito Christian S. Reiss Wayne Z. Trivelpiece William P. Patterson Steven D. Emslie 《Marine Biology》2013,160(6):1311-1323
Antarctic krill (Euphausia superba) occupy a key position in the Southern Ocean linking primary production to secondary consumers. While krill is a dominant grazer of phytoplankton, it also consumes heterotrophic prey and the relative importance of these two resources may differ with ontogeny. We used stable isotope analyses to evaluate body size-dependent trophic and habitat shifts in krill during the austral summer around the South Shetland Islands, Antarctica. We found evidence for an asymmetric, ontogenetic niche expansion with adults of both sexes having higher and more variable δ15N values but consistent δ13C values in comparison with juveniles. This result suggests that while phytoplankton likely remains an important life-long resource, krill in our study area expand their dietary niche to include higher trophic food sources as body size increases. The broader dietary niches observed in adults may help buffer them from recent climate-driven shifts in phytoplankton communities that negatively affect larval or juvenile krill that rely predominately on autotrophic resources. 相似文献
974.
975.
Kate E. Watermeyer Gurutzeta Guillera-Arroita Payal Bal Michael J. Burgass Lucie M. Bland Ben Collen Chris Hallam Luke T. Kelly Michael A. McCarthy Tracey J. Regan Simone Stevenson Brendan A. Wintle Emily Nicholson 《Conservation biology》2021,35(2):492-501
Global biodiversity indices are used to measure environmental change and progress toward conservation goals, yet few indices have been evaluated comprehensively for their capacity to detect trends of interest, such as declines in threatened species or ecosystem function. Using a structured approach based on decision science, we qualitatively evaluated 9 indices commonly used to track biodiversity at global and regional scales against 5 criteria relating to objectives, design, behavior, incorporation of uncertainty, and constraints (e.g., costs and data availability). Evaluation was based on reference literature for indices available at the time of assessment. We identified 4 key gaps in indices assessed: pathways to achieving goals (means objectives) were not always clear or relevant to desired outcomes (fundamental objectives); index testing and understanding of expected behavior was often lacking; uncertainty was seldom acknowledged or accounted for; and costs of implementation were seldom considered. These gaps may render indices inadequate in certain decision-making contexts and are problematic for indices linked with biodiversity targets and sustainability goals. Ensuring that index objectives are clear and their design is underpinned by a model of relevant processes are crucial in addressing the gaps identified by our assessment. Uptake and productive use of indices will be improved if index performance is tested rigorously and assumptions and uncertainties are clearly communicated to end users. This will increase index accuracy and value in tracking biodiversity change and supporting national and global policy decisions, such as the post-2020 global biodiversity framework of the Convention on Biological Diversity. 相似文献
976.
David A. Wiedenfeld Allison C. Alberts Ariadne Angulo Elizabeth L. Bennett Onnie Byers Topiltzin Contreras-MacBeath Gláucia Drummond Gustavo A. B. da Fonseca Claude Gascon Ian Harrison Nicolas Heard Axel Hochkirch William Konstant Penny F. Langhammer Olivier Langrand Frederic Launay Daniel J. Lebbin Susan Lieberman Barney Long Zhi Lu Michael Maunder Russell A. Mittermeier Sanjay Molur Razan Khalifa al Mubarak Michael J. Parr Jonah Ratsimbazafy Anders G. J. Rhodin Anthony B. Rylands Jim Sanderson Wes Sechrest Pritpal Soorae Jatna Supriatna Amy Upgren Jean-Christophe Vié Li Zhang 《Conservation biology》2021,35(5):1388-1395
Some conservation prioritization methods are based on the assumption that conservation needs overwhelm current resources and not all species can be conserved; therefore, a conservation triage scheme (i.e., when the system is overwhelmed, species should be divided into three groups based on likelihood of survival, and efforts should be focused on those species in the group with the best survival prospects and reduced or denied to those in the group with no survival prospects and to those in the group not needing special efforts for their conservation) is necessary to guide resource allocation. We argue that this decision-making strategy is not appropriate because resources are not as limited as often assumed, and it is not evident that there are species that cannot be conserved. Small population size alone, for example, does not doom a species to extinction; plants, reptiles, birds, and mammals offer examples. Although resources dedicated to conserving all threatened species are insufficient at present, the world's economic resources are vast, and greater resources could be dedicated toward species conservation. The political framework for species conservation has improved, with initiatives such as the UN Sustainable Development Goals and other international agreements, funding mechanisms such as The Global Environment Facility, and the rise of many nongovernmental organizations with nimble, rapid-response small grants programs. For a prioritization system to allow no extinctions, zero extinctions must be an explicit goal of the system. Extinction is not inevitable, and should not be acceptable. A goal of no human-induced extinctions is imperative given the irreversibility of species loss. 相似文献
977.
First study of congener group patterns and concentrations of short- and medium-chain chlorinated paraffins in fish from the North and Baltic Sea 总被引:4,自引:0,他引:4
This study presents the first investigation of concentrations and congener group patterns of short- (SCCPs) and medium-chain chlorinated paraffins (MCCPs) in fish from the North and Baltic Sea. North Sea dab, cod and flounder were studied. High resolution gas chromatography (HRGC) coupled to low resolution mass spectrometry (LRMS) in the electron capture negative ionization mode (ECNI) was employed. Good linearity (R2>0.993, 7 measuring points) was achieved between 1 and 100 ng/g of CP mixtures for SCCPs and MCCPs. The limits of detection were 0.5-1 ng/microl of CP mixture for the major congener groups of SCCPs and MCCPs. A clean-up comprising fat extraction, adsorption chromatography on silicagel impregnated with concentrated sulphuric acid and adsorption chromatography on Florisil was employed to avoid interferences from other polychlorinated compounds. Recoveries of CPs in spiked samples ranged between 80% and 100%. Accuracy was controlled with spiked samples and deviated not more than 10% from the expected values. Quantification was performed with standards of an average chlorine content as close as possible to that of the samples (SCCPs: 59-62%, MCCPs: 53-58%). SCCP concentrations ranged between 19 and 286 ng/g liver wet weight (ww), MCCP concentrations were comparable with a range of 25-260 ng/gww. Congener group patterns were also determined and discussed. In samples from the Baltic Sea the SCCP congener pattern was similar to that of commercial SCCP mixtures or C13 congeners were most abundant. In samples from the North Sea a higher relative abundance of C10 congeners was observed. 相似文献
978.
Michael E Barrett 《Water environment research》2005,77(1):78-86
This paper describes a method for comparing the pollutant removal of a number of structural stormwater treatment devices, commonly referred to as best management practices (BMPs). Historically, the pollutant removal ability of a BMP has been expressed as a percent reduction in concentration or load. Unfortunately, the calculated percent reduction in pollutant concentration is strongly affected by the influent concentration, with the calculated reduction generally being much lower when the event mean concentrations (EMCs) in the untreated runoff from the test watershed are low. The objective of the proposed methodology is to eliminate this problem by predicting BMP performance for an arbitrary influent concentration, so that BMPs evaluated in different watersheds can be compared as if the influent quality at all sites were the same. This method allows BMPs to be compared based on the quality of effluent produced and the mass reduction. The proposed method uses linear regression as the primary tool to compute the expected effluent concentration from a BMP, given a specific influent concentration of interest and was developed using data collected in the California Department of Transportation BMP Retrofit Pilot Program. This technique reveals that for media filters, the concentration of sediment and other particle-associated pollutants in treated runoff is generally unrelated to influent quality and is relatively constant. Wet basins with large permanent pool volumes also have effluent concentrations that are constant for most constituents and unrelated to influent concentrations. In these situations, the "percent reduction" in a pollutant EMC is not an inherent characteristic of the BMP, but a function of the influent EMC, because the quality of effluent produced is constant. Predicting the effluent quality of several types of conventional BMPs based on a common influent concentration allows an objective comparison of their performance and the selection of a BMP that addresses specific constituents of concern. 相似文献
979.
The chemical oxidation of trichloroethene dense non-aqueous phase liquid by permanganate was studied in an aqueous system using micro-reaction/extraction vessels in a novel approach. Experiments were conducted at ambient temperature ( approximately 20 degrees C) under static and mixed conditions to evaluate the rate of TCE(DNAPL) dissolution as a function of permanganate concentration. Chemical oxidation by permanganate was shown to increase the rate of TCE(DNAPL) dissolution under static conditions and decrease the rate of dissolution under mixed conditions. The apparent inconsistency in results appears to result from the local deposition of a film at the DNAPL interface composed of manganese oxide solids as discovered through visual observation with the aid of a Goniometer. Data from interfacial deposition experiments suggest that the film formed rapidly and reached maturation within approximately 2 h with little or no growth occurring thereafter. A conceptual model of the reaction and mass transfer processes occurring at the DNAPL interface was proposed based on the experimental results. 相似文献
980.