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Siu-Yin Theresa Leung Ross V. Bulkley John J. Richards 《Journal of the American Water Resources Association》1982,18(3):485-493
ABSTRACT: Estimates were made of the amounts of selected pesticides entering and leaving Saylorville Reservoir, a new partly filled impoundment on the Des Moines River. Samples were collected at 1– or 2-week intervals at stations above, in, and below the reservoir. Atrazine, alachlor, and cyanazine were found only in the dissolved state, and dieldrin and p, p′ -DDE in both the, dissolved and suspended state. Heptachlor epoxide, p,p-DDT. p, p′ -DDD, 2,4-D, 2,4,5-TP, endrin, lindane, methoxychlor, propachlor, and toxaphene were not detected or were at very low concentrations. Estimated deposition in the reservoir from September 1977 to October 1978 was 281 kg atrazine, 251 kg alachlor, 26 kg cyanazine, 16 kg dieldrin, and 20 kg p, p′ -DDE. 相似文献
44.
Anna Leung Zong Wei Cai Ming Hung Wong 《Journal of Material Cycles and Waste Management》2009,11(3):173-173
Special FeatureWaste Management Research in Korea
A new joint publication 相似文献45.
Sustaining Visitor Use in Protected Areas: Future Opportunities in Recreation Ecology Research Based on the USA Experience 总被引:4,自引:1,他引:3
Christopher A. Monz David N. Cole Yu-Fai Leung Jeffrey L. Marion 《Environmental management》2010,45(3):551-562
Recreation ecology, the study of environmental consequences of outdoor recreation activities and their effective management,
is a relatively new field of scientific study having emerged over the last 50 years. During this time, numerous studies have
improved our understanding of how use-related, environmental and managerial factors affect ecological conditions and processes.
Most studies have focused on vegetation and soil responses to recreation-related trampling on trails and recreation sites
using indicators such as percent vegetation cover and exposed mineral soil. This applied approach has and will continue to
yield important information for land managers. However, for the field to advance, more attention needs to be given to other
ecosystem attributes and to the larger aspects of environmental conservation occurring at landscape scales. This article is
an effort at initiating a dialog on needed advances in the field. We begin by reviewing broadly generalizable knowledge of
recreation ecology, to separate what is known from research gaps. Then, based on the authors’ perspective of research in the
USA and North America, several research directions are suggested as essential for continued progress in this field including
theoretical development, broadening scale, integration with other disciplines, and examination of synergistic effects. 相似文献
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Developing a Monitoring Protocol for Visitor-Created Informal Trails in Yosemite National Park,USA 总被引:1,自引:0,他引:1
Informal trails created or perpetuated by visitors is a management challenge in many protected natural areas such as Yosemite
National Park. This is a significant issue as informal trail networks penetrate and proliferate into protected landscapes
and habitats, threatening ecological integrity, aesthetics, and visitor experiences. In order to develop effective strategies
for addressing this problem under an adaptive management framework, indicators must be developed and monitoring protocol must
be established to gather timely and relevant data about the condition, extent, and distribution of these undesired trail segments.
This article illustrates a process of developing and evaluating informal trail indicators for meadows in Yosemite Valley.
Indicator measures developed in past research were reviewed to identify their appropriateness for the current application.
Information gaps in existing indicator measures were addressed by creating two new indices to quantify the degree of informal
trailing based on its land fragmentation effects. The selected indicator measures were applied to monitoring data collected
between 2006 and 2008. The selected measures and indices were evaluated for their ability to characterize informal trail impacts
at site and landscape scales. Results demonstrate the utility of indicator measures in capturing different characteristics
of the informal trail problem, though several metrics are strongly related to each other. The two fragmentation indices were
able to depict fragmentation without being too sensitive to changes in one constituent parameter. This study points to the
need for a multiparameter approach to informal trail monitoring and integration with other monitoring data. Implications for
monitoring programs and research are discussed. 相似文献
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Local adaptation of immunity against a trematode parasite in marine amphipod populations 总被引:1,自引:0,他引:1
Resources allocated to defence against parasites are not available for investment in other functions such as growth or reproduction,
resulting in trade-offs between different components of an organism’s fitness. In balancing the cost of infection and the
cost of immunity, selection should only favour individuals that allocate more energy to resistance and immune responses in
populations regularly exposed to debilitating parasites. Here, we compare the ability of amphipods, Paracalliope novizealandiae, to (1) avoid becoming infected and (2) to respond to infection by encapsulating and melanizing parasites, between two natural
populations exposed to different risk of parasitism. One population faces high levels of infection by the debilitating trematode
parasite Maritrema novaezealandensis, whereas the other population is not parasitised by this trematode nor by any other parasite. Under controlled experimental
conditions, with exposure to a standardized dose of parasites, amphipods from the parasite-free population acquired significantly
more parasites than those from the population regularly experiencing infection. Furthermore, a lower frequency of amphipods
from the parasite-free population succeeded at melanizing (and thus killing) parasites, and they melanized a lower percentage
of parasites on average, than amphipods from the parasitised population. These differences persist when individual factors,
such as amphipod sex or body length, are taken into account as potential confounding variables. These results support the
existence of local adaptation against parasites: an amphipod population that never experiences trematode infections is less
capable of resisting infection, both in terms of its first line of defence (avoiding infection) and a later line of defence
(fighting parasites following infection), than a population regularly exposed to infection. 相似文献