全文获取类型
收费全文 | 1791篇 |
免费 | 56篇 |
国内免费 | 21篇 |
专业分类
安全科学 | 88篇 |
废物处理 | 70篇 |
环保管理 | 406篇 |
综合类 | 175篇 |
基础理论 | 506篇 |
环境理论 | 5篇 |
污染及防治 | 418篇 |
评价与监测 | 122篇 |
社会与环境 | 53篇 |
灾害及防治 | 25篇 |
出版年
2023年 | 19篇 |
2022年 | 36篇 |
2021年 | 48篇 |
2020年 | 24篇 |
2019年 | 42篇 |
2018年 | 53篇 |
2017年 | 59篇 |
2016年 | 78篇 |
2015年 | 49篇 |
2014年 | 66篇 |
2013年 | 151篇 |
2012年 | 84篇 |
2011年 | 127篇 |
2010年 | 79篇 |
2009年 | 94篇 |
2008年 | 105篇 |
2007年 | 97篇 |
2006年 | 104篇 |
2005年 | 54篇 |
2004年 | 50篇 |
2003年 | 59篇 |
2002年 | 45篇 |
2001年 | 26篇 |
2000年 | 44篇 |
1999年 | 20篇 |
1998年 | 19篇 |
1997年 | 9篇 |
1996年 | 21篇 |
1995年 | 18篇 |
1994年 | 20篇 |
1993年 | 10篇 |
1992年 | 11篇 |
1991年 | 9篇 |
1990年 | 8篇 |
1989年 | 12篇 |
1988年 | 11篇 |
1987年 | 10篇 |
1986年 | 11篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1983年 | 10篇 |
1982年 | 13篇 |
1981年 | 14篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1975年 | 4篇 |
1969年 | 4篇 |
1958年 | 2篇 |
排序方式: 共有1868条查询结果,搜索用时 0 毫秒
61.
62.
Daniel H. Henning 《The Environmentalist》1981,1(2):127-132
Summary This paper focuses on the emphasis placed on environmental considerations and values in the context of environmental in-service training programs for governmental personnel in England, Austria, the Federal Republic of Germany, and the Netherlands. The paper is generally based on field research conducted in Europe during August 1979; issues were identified and comparisons were made with training programs in the United States. The major issues considered include: (1) early versus later emphasis, (2) resistance, (3) specialists and techno-scientific emphasis, (4) technique orientations, (5) lack of environmental administrative training, and (6) innovations.Despite various contrasts between European and United States environmental in-service training programs, there are some similarities. Many of these similarities center around a lack of emphasis on environmental training per se as well as on a lack of emphasis on environmental considerations and values because of various constraints, perceptions, and orientations. As developed nations with advanced governmental-technological systems in environmental affairs, their training programs are highly oriented toward these systems, and there is a lack of attention devoted to environmental aspects per se. The environmental titles and responsibilities do not automatically insure the incorporation of environmental considerations and values into the policy-making process with obvious training needs.European governments may adhere to a more legalistic, formal, and structured approach with less discretion available. But specialist and administrative personnel, as in the United States, are intimately involved in value judgments and decision-making in environmental affairs. Because of this, training programs have a special responsibility to educate personnel about environmental considerations and values to insure that the environmental public interest is adequately presented in the decision-making process, i.e., that they develop environmental competencies as well as governmental and technological ones on an interface basis.Dr Daniel H. Henning is Professor of Political Science and Distinguished Scholar Professor at Eastern Montana College. His interest and expertise is in the field of environmental training for government officials. 相似文献
63.
Polybrominated diphenyl ethers (PBDEs) have been used extensively as brominated flame retardants (BFRs) in textiles, upholstery and electronics. They are ubiquitous contaminants in wildlife and humans. A low concentration of nonabrominated diphenyl ethers (nonaBDEs) is present in commercial DecaBDE and they are also abiotic and biotic debromination products of decabromodiphenyl ether (BDE-209). The objective of the present work was to develop methods for synthesis of the three nonaBDEs, 2,2',3,3',4,4',5,5',6-nonabromodiphenyl ether (BDE-206), 2,2',3,3',4,4',5,6,6'-nonabromodiphenyl ether (BDE-207) and 2,2',3,3',4,5,5',6,6'-nonabromodiphenyl ether (BDE-208), with the intention of making them available as authentic standards for analytical, toxicological and stability studies, as well as studies regarding physical-chemical properties. Two methods were developed, one based on perbromination of phenoxyanilines and the other via reductive debromination of BDE-209 by sodium borohydride followed by chromatographic separation of the three nonaBDE isomers formed. An additional nonabrominated compound, 4'-chloro-2,2',3,3',4,5,5',6,6'-nonabromodiphenyl ether (Cl-BDE-208), was also synthesized in the present work. Cl-BDE-208, prepared by the perbromination of 4-chlorodiphenyl ether, may be used as an internal standard in analysis of highly brominated diphenyl ethers. BDE-206, BDE-207, BDE-208 and Cl-BDE-208 were characterized by 1H NMR, 13C NMR, electron ionization mass spectra and by their melting points. The structures of all three nonaBDEs have been characterized previously by X-ray crystallography. 相似文献
64.
Connell DP Withum JA Winter SE Statnick RM Bilonick RA 《Journal of the Air & Waste Management Association (1995)》2005,55(5):559-573
One-hour average ambient concentrations of particulate matter (PM) with an aerodynamic diameter < 2.5 microm (PM2.5) were determined in Steubenville, OH, between June 2000 and May 2002 with a tapered element oscillating microbalance (TEOM). Hourly average gaseous copollutant [carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxide (NOx), and ozone (O3)] concentrations and meteorological conditions also were measured. Although 75% of the 14,682 hourly PM2.5 concentrations measured during this period were < or = 17 microg/m3, concentrations > 65 microg/m3 were observed 76 times. On average, PM2.5 concentrations at Steubenville exhibited a diurnal pattern of higher early morning concentrations and lower afternoon concentrations, similar to the diurnal profiles of CO and NO(x). This pattern was highly variable; however, PM2.5 concentrations > 65 microg/m3 were never observed during the mid-afternoon between 1:00 p.m. and 5:00 p.m. EST. Twenty-two episodes centered on one or more of these elevated concentrations were identified. Five episodes occurred during the months June through August; the maximum PM2.5 concentration during these episodes was 76.6 microg/m3. Episodes occurring during climatologically cooler months often featured higher peak concentrations (five had maximum concentrations between 95.0 and 139.6 microg/m3), and many exhibited strong covariation between PM2.5 and CO, NO(x), or SO2. Case studies suggested that nocturnal surface-based temperature inversions were influential in driving high nighttime concentrations of these species during several cool season episodes, which typically had dramatically lower afternoon concentrations. These findings provide insights that may be useful in the development of PM2.5 reduction strategies for Steubenville, and suggest that studies assessing possible health effects of PM2.5 should carefully consider exposure issues related to the intraday timing of PM2.5 episodes, as well as the potential for toxicological interactions among PM2.5, and primary gaseous pollutants. 相似文献
65.
Houle D Duchesne L Moore JD Laflèche MR Ouimet R 《Journal of environmental quality》2002,31(6):1993-2000
An evaluation of the impact of dolomitic lime [CaMg(CO3)2] on soils (five years after treatment) and sapwood chemistry (after four growing seasons) was realized for a Ca-deficient sugar maple stand at the lake Clair watershed. The effect on humus chemistry was significant: exchangeable Mg and Ca, effective acidity (EA), base saturation (BSe), pH, and effective cation exchange capacity (CECe) significantly increased, while exchangeable Fe significantly decreased. In the B horizon, liming increased exchangeable Ca, Mg, and Mn concentrations while decreasing other acid cations. No significant temporal trends in element concentrations in tree rings could be detected, although the lime treatment significantly changed the average xylem Mg and Mn concentrations as well as the average Mg/Mn and Ca/Mn ratios of the sapwood. The absence of temporal trends in rings from the last 20 yr implied a significant re-equilibration of elements through the sapwood. Significant relationships were found between averaged xylem Ca/Mn and Mg/Mn ratios and exchangeable humus Ca, Mg, Mn, Al, Fe, and H+ concentration, EA, CECe, and BSe, suggesting that the average xylem Ca/Mn and Mg/Mn ratios are strong indicators of the soil acid-base status. 相似文献
66.
Under what conditions do critical events trigger large-scale public discussion and mobilisation, and can these lead to policy change? In a comparative study of nuclear energy policy after the Japanese Fukushima disaster in March 2011, a theory-development approach is adopted, mobilising data collected from national news agencies’ newswires, public surveys, legislation and parliamentary databases, and newspaper editorials in 12 established democracies between March 2011 and March 2013. The analysis suggests two main hypotheses that can guide future research: critical events are more likely to trigger policy change when intense (contentious) mobilisation from policy challengers aligns with the views of the general public, and is backed by major political allies; and critical events are more likely to trigger intense (contentious) mobilisation when policy challengers articulate their opposition around pre-existing policy debates on the issue and resort to pre-existing organisational and mobilisation resources. 相似文献
67.
68.
Jean-Claude Grégoire Daniel Couillien Ralph Krebber Winfried A. König Holger Meyer Wittko Francke 《Chemoecology》1992,3(1):14-18
Summary The predator,Rhizophagus grandis, is linked to its specific prey,Dendroctonus micans, by semiochemical signals regulating oviposition and long range orientation. A mixture of simple oxygenated monoterpenes [(–)—fenchone, (–)—pinocamphone, rac. camphor, terpinene-4-ol, borneol, fenchol and verbenone], identified from the frass ofD. micans has been found to be extremely active in a flight windtunnel as a long—range attractant for the predator. The mixture elicited 84 % of the response to larval frass of the prey. Excluding pinocamphone from the mixture did not influence its activity. Also, changing the absolute configurations of some of the components (fenchol, terpinene-4-ol and borneol) did not influence the predators' response. However, the addition of (–)—-terpineol increased the attractivity of the synthetic blend to almost that of larval frass of the prey. Ecological implications of the identified semiochemicals and their use in pest management are discussed. 相似文献
69.
70.
Daniel T. Blumstein Louise Cooley Jamie Winternitz Janice C. Daniel 《Behavioral ecology and sociobiology》2008,62(3):457-468
We conducted four experiments to determine whether yellow-bellied marmots, Marmota flaviventris, discriminate among predator vocalizations, and if so, whether the recognition mechanism is learned or experience-independent.
First, we broadcast to marmots the social sounds of coyotes, Canis latrans, wolves, Canis lupus, and golden eagles, Aquila chrysaetos, as well as conspecific alarm calls. Coyotes and eagles are extant predators at our study site, while wolves have been absent
since the mid-1930s. In three follow-up experiments, we reversed the eagle call and presented marmots with forward and reverse
calls to control for response to general properties of call structure rather than those specifically associated with eagles,
we tested for novelty by comparing responses to familiar and unfamiliar birds, and we tested for the duration of predator
sounds by comparing a wolf howl (that was much longer than the coyote in the first experiment) with a long coyote howl of
equal duration to the original wolf. Marmots suppressed foraging and increased looking most after presentation of the conspecific
alarm call and least after that of the coyote in the first experiment, with moderate responses to wolf and eagle calls. Marmots
responded more to the forward eagle call than the reverse call, a finding consistent with a recognition template. Marmots
did not differentiate vocalizations from the novel and familiar birds, suggesting that novelty itself did not explain our
results. Furthermore, marmots did not differentiate between a wolf howl and a coyote howl of equal duration, suggesting that
the duration of the vocalizations played a role in the marmots’ response. Our results show that marmots may respond to predators
based solely on acoustic stimuli. The response to currently novel wolf calls suggests that they have an experience-independent
ability to identify certain predators acoustically. Marmots’ response to predator vocalizations is not unexpected because
25 of 30 species in which acoustic predator discrimination has been studied have a demonstrated ability to respond selectively
to cues from their predators. 相似文献