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921.
There are numerous demands for the limited water supplies in the Rocky Mountain (USA) region, and controversies surrounding
instream flows abound. A specific problem involves water diversions (i.e., small dams that shunt water out of stream channels)
during the summer irrigation season. We developed an approach to assess the effects of restoration of natural or less-than-natural
summer flows on trout that accounts for variation in habitat over long segments of low-gradient, alluvial-valley streams.
The approach has utility for managers because it can be conducted with hydologic data, aerial photographs, topographic maps,
and a spreadsheet without extensive fieldwork. We applied the approach by assessing the effects of different summer flows
on abundance of brown trout (Salmo trutta) in several streams annually dewatered in the Salt River Valley of western Wyoming. The assessment approach can be calibrated
for other trout species and areas of the Rocky Mountain region. 相似文献
922.
The objective of this study was to assess the radiative forcing due to Finnish anthropogenic greenhouse gas emissions in three
scenarios. All the Kyoto Protocol gases, i.e., CO2, CH4, N2O, and fluorinated gases, were included. The calculations showed that forcing due to Finnish emissions will increase in the
case of all gases except methane by the year 2100. In 1990, radiative forcing due to Finland's emission history of all Kyoto
Protocol gases was 3.2 mW/m2, of which 71% was due to carbon dioxide, 17% to methane, and the rest to nitrous oxide. In 1990 the share of fluorinated
gases was negligible. The share of methane in radiative forcing is decreasing, whereas the shares of carbon dioxide and of
fluorinated gases are increasing and that of nitrous oxide remains nearly constant. The nonlinear features concerning additional
concentrations in the atmosphere and radiative forcing due to emissions caused by a single country or activity are also considered.
Radiative forcing due to Finnish emissions was assessed with two different approaches, the marginal forcing approach and the
averaged forcing approach. The impact of the so-called background scenario, i.e., the scenario for concentration caused by
global emissions, was also estimated. The difference between different forcing models at its highest was 40%, and the averaged
forcing approach appeared to be the more recommendable. The effect of background concentrations in the studied cases was up
to 11%. Hence, the choice of forcing model and background scenario should be given particular attention. 相似文献
923.
The European Union's Structural Funds are implemented by means of Regional Development Plans (RDP), whose regionally scoped environmental assessment is required. We highlight the deficiencies faced by this approach when subregional areas with high conservation natural values are involved and illustrate it with the case of the RDP of Andalusia region on Doñana National Park area (Spain). Commissioned by the World Wildlife Fund, a Strategic Environmental Assessment (SEA) of the Andalusian RDP was carried out focusing on Doñana and its area of influence. This is a complex space where some of the most environmentally valuable features in the continent coexist with a surrounding intense and multi-sector economic activity, threatening its conservation. In the absence of an established sustainability framework in the Region, a “trickle-down” SEA approach evidenced the need to produce a set of environmental, economic and social guidelines for sustainable management of land, against which the RDP objectives were tested for coherence. An “incremental” SEA approach was also tested, which involved the identification of 79 measures and actions stemming from the RDP provisions and other concurrent planning documents reviewed and the qualitative assessment of their individual and cumulative potential impacts on Doñana environments. In the light of the results, a set of complementary mitigating measures was proposed for inclusion in tiered stages of the planning process. Measures to avoid, reduce, remedy and monitor the major types of impact were proposed, including provisions for public participation. SEA emerges as an instrument for non-governmental organizations (NGOs) to carry out independent assessment of public development initiatives. 相似文献
924.
We sent out a targeted questionnaire to organizations and private individuals across the UK that have expressed an interest
in squirrel management and conservation. Respondents were asked to evaluate shooting, trapping, poisoning and immunocontraception
(IMC), according to their perceived efficacy, cost efficiency, and whether they were considered to be humane. The majority
of both professionals and enthusiasts indicated support for grey squirrel control to help conserve red squirrels and to reduce
economic damage to timber crops. Respondents\' comparative evaluations of current forms of control showed that trapping is
the most acceptable method. When IMC is compared with the other methods, it was considered to be more humane and acceptable.
In contrast, poisoning was seen as humane or acceptable by the fewest respondents. Furthermore, poisoning elicited the greatest
difference in opinion between the professional and enthusiast groups. This difference (34\%) may be interpreted partly as
concern over the type of death that results from poisoning and partly as due to the possibility of poisoning nontarget species.
Our findings indicate a need for more public information regarding secondary poisoning hazards to other species and their
predators. Interest and concern about squirrel control correlated with the overlap between contemporary areas of distribution
of the two species. It is these areas where consultation and education programs about control methods should be targeted.
This research indicates that there would be support for grey squirrel control using IMC from both lay and professional interest
groups. It demonstrates the existence of a sound basis for constructive dialog that can lead to the design and implementation
of acceptable and efficient control strategies. 相似文献
925.
We applied the Theory of Planned Behavior to help understand the relationships between environmental beliefs, support for
ecosystem restoration actions, and willingness to pay (WTP) for restoration and protection goals in the Hudson River estuary,
New York State, USA. We conducted a mail survey with 3,000 randomly-chosen local residents of the Hudson River estuary in
the fall of 1999. As hypothesized, the broad ecosystem restoration goals of the Hudson River Estuary Action Plan were more
strongly supported than the corresponding specific implementation actions. We found that beliefs and past behavior were better
explanatory variables than sociodemographic characteristics for explaining people's support for ecosystem restoration actions
and WTP for restoration and protection goals. Because ecosystem restoration goals appear to be more generally acceptable than
specific restoration actions, proponents of restoration programs should not become complacent about the need for active public
outreach and involvement even if initial restoration program discussions have been low in controversy. Efforts to assess and
foster support for ecosystem restoration should be targeted toward audiences identified on the basis of beliefs and past behaviors
rather than on sociodemographic characteristics. 相似文献
926.
Riparian livestock exclosure research in the western United States: a critique and some recommendations 总被引:1,自引:1,他引:0
Sarr DA 《Environmental management》2002,30(4):516-526
Over the last three decades, livestock exclosure research has emerged as a preferred method to evaluate the ecology of riparian
ecosystems and their susceptibility to livestock impacts. This research has addressed the effects of livestock exclusion on
many characteristics of riparian ecosystems, including vegetation, aquatic and terrestrial animals, and geomorphology. This
paper reviews, critiques, and provides recommendations for the improvement of riparian livestock exclosure research. Exclosure-based
research has left considerable scientific uncertainty due to popularization of relatively few studies, weak study designs,
a poor understanding of the scales and mechanisms of ecosystem recovery, and selective, agenda-laden literature reviews advocating
for or against public lands livestock grazing. Exclosures are often too small (<50 ha) and improperly placed to accurately
measure the responses of aquatic organisms or geomorphic processes to livestock removal. Depending upon the site conditions
when and where livestock exclosures are established, postexclusion dynamics may vary considerably. Systems can recover quickly
and predictably with livestock removal (the “rubber band” model), fail to recover due to changes in system structure or function
(the “Humpty Dumpty” model), or recover slowly and remain more sensitive to livestock impacts than they were before grazing
was initiated (the “broken leg” model). Several initial ideas for strengthening the scientific basis for livestock exclosure
research are presented: (1) incorporation of meta-analyses and critical reviews. (2) use of restoration ecology as a unifying
conceptual framework; (3) development of long-term research programs; (4) improved exclosure placement/design; and (5) a stronger
commitment to collection of pretreatment data. 相似文献
927.
Ecosystem management and sustainable forestry on mixed ownership landscapes will require some level of cross-boundary coordination
or management. Oregon's experiment with local, voluntary, collaborative forums, called watershed councils, is one mechanism
to foster cross-boundary management. Fifty qualitative, in-depth interviews in three study areas were conducted with nonindustrial
private forest (NIPF) landowners, watershed council members, and agency employees to learn how and why landowners participate
(or not) on watershed councils. Study areas were located in three different areas of the state to reflect different ecological
and organizational settings. Our case study identified three themes—stewardship ethic, property rights amid uncertainty, and
action orientation—that were most salient among landowners when deciding to participate in their local watershed council.
Other factors related to competing opportunities were also identified. Our results relate to the social psychological antecedents
to cooperation of perceived consensus, group identity, and legitimacy of authority as well as to applied situations where
cross-boundary coordination and management are goals. 相似文献
928.
Quantifying natural resource injuries and ecological service reductions: challenges and opportunities 总被引:1,自引:0,他引:1
The natural resource damage assessment (NRDA) provisions of the Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA) and the Oil Pollution Act (OPA) are complex and have been difficult to implement. The complexity and difficulty
in implementation arise both from the assessment procedures specified in agency NRDA guidance and from the limited ability
of ecologists to quantify impacts of hazardous substances on natural resources. This paper explores the scientific aspects
of NRDA implementation, and discusses conceptual and methodological relationships between NRDA and the much broader field
of ecological risk assessment (ERA). We discuss three critical components of the NRDA assessment approach: measuring natural
resource injuries and reductions in resource services; evaluating causality; and establishing baseline conditions. We identify
(1) specific approaches drawn from ERA practice that could improve each of these components, and (2) research needs and institutional
changes that may improve the ability of the NRDA process to achieve its stated objectives. We recommend the acceleration of
the ongoing dialogue among NRDA practitioners from the Trustee and PRP communities as a first step toward resolving the procedural
and technical deficiencies of the NRDA process. 相似文献
929.
Spartina pectinata (prairie cordgrass) was grown under five hydroperiods (wet–dry cycles) to determine its potential for use in stormwater wetlands,
particularly as an alternative to the highly invasive Phalaris arundinacea (an exotic grass). Rhizomes planted in outdoor microcosms grew vigorously in all treatments, namely, weekly flooding in early
summer, weekly flooding in late summer, flooding every three weeks throughout the summer, weekly flooding throughout the summer,
and no flooding. Neither the timing nor frequency of 24-hour floods (10–20 cm deep) affected total stem length (grand mean
1003 ± 188.8 cm per pot, n = 140) or above-ground biomass (46.5 ± 8.3 g per pot, equivalent to ∼360 g/m2). However, by late summer, fewer new tillers were found in unflooded microcosms, indicating that vegetative expansion is
drought-sensitive.
The growth of Spartina plants was further assessed with and without Glyceria striata (a native grass) and Phalaris arundinacea. Glyceria growth was not affected by hydrologic treatment. Glyceria reduced Spartina growth by approximately 11%, suggesting potential as a cover crop that might reduce establishment and growth of Phalaris seedlings. Seeds of Phalaris did not germinate, but branch fragments established where soil was moist from flooding, regardless of the presence of Glyceria. The ability of Spartina to establish vegetatively and grow well under variable water levels leads us to recommend further testing in stormwater wetlands,
along with early planting of Glyceria to reduce weed invasions. 相似文献
930.
Increasing atmospheric concentrations of greenhouse gases are widely expected to cause global warming and other climatic changes.
It is important to establish priorities for reducing greenhouse-gas emissions, so that resources can be allocated efficiently
and effectively. This is a global problem, and it is possible, on a global scale, to identify those activities whose emissions
have the greatest potential for enhancing the greenhouse effect. However, perspectives from smaller scales must be appreciated,
because it is on scales down to the local level that response measures will be implemented. This paper analyzes the relative
importance of emissions from the many individual sources, on scales ranging from global to national to subnational. Individual
country perspectives and proposed policy measures and those of subnational political entities exhibit some commonalities but
differ among themselves and from a global-scale perspective in detail. 相似文献