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491.
The ecological systems of Earth are subjected to a wide array of environmental stresses resulting from human activities. The
development of appropriate environmental protection and management policies and the appropriate allocation of resources across
environmental stresses require a systematic evaluation of relative risks. The data and methodologies for comprehensive ecological
risk assessment do not exist, yet we do have considerable understanding of econological stress-response relationships. A methodology
is presented to utilize present knowledge for assignment of relative risks to ecological systems and human welfare from anthropogenic
stresses. The resultant priorities, developed for the US Environmental Protection Agency's (EPA) relative risk reduction project,
highlight global climate change, habitat alteration, stratospheric ozone depletion, and species depletion as the highest environmental
risks, significantly diverging from the present emphasis by EPA and the public on toxic chemical issues. Enhanced attention
to ecological issues by EPA and development of ecological risk assessment methodologies that value ecological and economic
issues equitably are key recommendations. 相似文献
492.
William O. Rasmussen 《Environmental management》1992,16(3):389-396
Several approaches can be used to define and construct visual buffer strips around proposed new facility sites in a forested
environment. A visual buffer strip of a given value, defines a region around an object within which the probability of an
unblocked view of all or portions of it by an observer are less than the buffer strip probability value. Two primary approaches
are used to define visual buffer strips that take into account the size of the vegetative elements and their individual effects
on visibility. Several variations and combinations of the approaches are possible. One approach defines a visual buffer strip
based on the average probability of a clear view of points along the object by an observer; the other approach is based on
the visibility of the feature as a whole. The computation and construction of visual buffer strips based on these two concepts
are presented. Comparisons of the two approaches for specific feature shapes are also described. 相似文献
493.
Cancer risk factors (characterized by route, dose, dose rate per kilogram, fraction of lifetime exposed, species, and sex)
were derived for workers exposed to benzene via inhalation or ingestion. Exposure at the current Occupational Safety and Health
Administration (OSHA) permissible exposure limit (PEL) and at leaking underground storage tank (LUST) sites were evaluated.
At the current PEL of 1 ppm, the theoretical lifetime excess risk of cancer from benzene inhalation is ten per 1000. The theoretical
lifetime excess risk for worker inhalation exposure at LUST sites ranged from 10 to 40 per 1000. These results indicate that
personal protection should be required. The theoretical lifetime excess risk due to soil ingestion is five to seven orders
of magnitude less than the inhalation risks. 相似文献
494.
William H. Bruvold 《Journal of the American Water Resources Association》1992,28(4):775-782
ABSTRACT: Individuals naturally engage in sensory evaluation of water quality during daily consumption. Efforts to ensure that all consumers receive high quality water must attend to sensory evaluation; otherwise individuals can obtain repeated evidence of compromised quality that reduces confidence in public purveyors and regulating agencies. Sensory quality is currently regulated by the United States Environmental Protection Agency (USEPA) by promulgation of secondary maximum contaminant levels (SMCLs) governing taste and odor in drinking water. Efforts to establish new SMCLs for identified organic contaminants has been thwarted by a lack of research data even though standardized methods for sensory evaluation presently exist. The present paper recommends a broad based national research program designed to produce odor detection thresholds, flavor detection thresholds, flavor acceptability functions, flavor recognition thresholds, and flavor intensity functions for each current contaminant of concern which will provide a substantial basis for the desired SMCLs, and offer an unprecedented comparative evaluation of currently standardized sensory evaluation procedures. 相似文献
495.
William A. Duvel 《补救:环境净化治理成本、技术与工艺杂志》1992,2(3):235-247
The ten management guidelines discussed in this article can help site owners (and their remediation consultants) achieve environmental results that are acceptable to government regulators—at the lowest possible cost to all concerned. They remind site owners to learn everything possible about the nature and extent of their contamination problems, then maintain control of the cleanup process by defining obligations in consulting contracts and establishing positive working relationships with regulatory agencies. 相似文献
496.
William R. Walker Carol J. Haley Phyllis Bridgeman Stephen H. Goldstein 《Environmental management》1991,15(3):441-449
A literature search and survey of Virginia, USA, campgrounds with RV pump-out stations were used to determine whether boat
holding-tank deodorant chemicals would have deleterious effects on marina septic systems or package treatment plants. Laboratory
studies reported in the literature indicate that these chemical additives could affect septic system function in three ways:
(1) active ingredients in the additives can impair sewage degradation in septic tanks, causing sludge buildup and overflow
of solids into the drainfield, (2) additive chemicals might enter the drainfield and, in high enough concentrations, reduce
the drainfield's ability to degrade waste, or (3) toxic additive chemicals might migrate from the drainfield to ground or
surface water. Laboratory studies also show that some ingredients added to holding tanks interfere with functioning of activated
sludge treatment process. Experience in the field and in other laboratory studies suggests that factors such as dilution of
treated waste with untreated waste and the characteristics of the sewage to be treated can reduce the possibility of damage
to septic and activated sludge systems. The campground owners surveyed indicated that they have few problems with their septic
systems in spite of the presence of chemical additives in the RV waste. However, most of them practice good septic system
maintenance and have devised other means of ensuring that their systems function efficiently. In addition, the survey indicates
that most Virginia campgrounds get only seasonal use (as would marinas in Virginia), allowing their systems to recover between
peak seasons. 相似文献
497.
William Yaw Osei 《The Environmentalist》1996,16(3):231-239
Summary Agro-ecosystems in many of the developing economies are coming under increased pressure, especially in areas where population demands, weak economic growth, and debt burdens, are resulting in mass rural poverty and assault on environmental resources. The loss of forests is a double-edge blow for most rural and agricultural systems. The forests provide the resource substitutes for the many manufactured products which are scarce or physically and economically inaccessible, and they also provide congenial environments which support rural food systems by way of productive agricultural land opportunities.In many of the rural areas of Africa, in particular, forest stability is more threatened, and this requires both local and external responses to make sustainable development a possibility. This paper, which is based on a field study in Ghana by the author, identifies emerging socio-economic constraints in woodfuel systems in environments where demands on forest ecosystems are high. The degree to which such local socio-economic processes affect stability of forest ecosystems, and the conditions within which the research information could assist planners and resource managers towards sustainable use of forest ecosystems are analysed.Dr William Y. Osei was born in Ghana where he obtained a BA (Hons) Geography from the University of Ghana. He subsequently obtained an MA from Carleton University, Ottawa, Canada and a PhD from the University of Western Ontario, London, Canada. With teaching experience in Geography at the Canadian universities of Western Ontario, Brandon and Victoria, he currently holds the position of Assistant Professor in the Department of Geography at Algoma University College. 相似文献
498.
OEIS complex (exstrophy of the cloaca) is an association of fetal malformations that includes omphalocele, exstrophy of the bladder, imperforate anus, and spinal defects. Most cases should be prenatally detectable by maternal serum alpha-fetoprotein screening, but an accurate diagnosis is essential for appropriate counselling of the family. 相似文献
499.
500.
Assessing the Vulnerability of Coastal Communities to Extreme Storms: The Case of Revere,MA., USA 总被引:6,自引:1,他引:6
Clark George E. Moser Susanne C. Ratick Samuel J. Dow Kirstin Meyer William B. Emani Srinivas Jin Weigen Kasperson Jeanne X. Kasperson Roger E. Schwarz Harry E. 《Mitigation and Adaptation Strategies for Global Change》1998,3(1):59-82
Climate change may affect the frequency, intensity, and geographic distribution of severe coastal storms. Concurrent sea-level
rise would raise the baseline of flooding during such events. Meanwhile, social vulnerability factors such as poverty and
disability hinder the ability to cope with storms and storm damage. While physical changes are likely to remain scientifically
uncertain into the foreseeable future, the ability to mitigate potential impacts from coastal flooding may be fostered by
better understanding the interplay of social and physical factors that produce human vulnerability. This study does so by
integrating the classic causal model of hazards with social, environmental, and spatial dynamics that lead to the differential
ability of people to cope with hazards. It uses Census data, factor analysis, data envelopment analysis, and floodplain maps
to understand the compound social and physical vulnerability of coastal residents in the city of Revere, MA, USA.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献