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301.
302.
The objective of this paper is to discuss the benefits and risks of providing drinkers with tools that allow them to estimate their blood alcohol concentration (BAC), and to examine the field usability of one commercially available tool. Drinking and driving laws are specified in terms of the driver's BAC, and there is concern that the absence of a method for drivers to accurately estimate their BAC level limits their ability to determine whether they can drive legally. A number of devices that provide a method for the individual to estimate or measure their BAC have been developed. Although some of these devices--such as the "know your limit" (KYL) cards--have been widely distributed, their effectiveness in encouraging good driving decisions have rarely been tested. This article describes a pilot study on the field usability of the Guardian Angel (GA) personal alcohol test in a field setting. The GA test analyzes saliva samples from drinking and indicates under which BAC category they fall (.00 -.04;.04 -.08;.08+). The research examined whether drinkers could, in natural drinking environments, correctly administer and interpret the test results. The methodology involves sampling drinkers on a weekend night on and around the grounds of a large West Coast university as they traveled between off-campus parties, bars, and their dorms. They were asked to assess their own intoxication and impairment, then self-administer and interpret the Guardian Angel test. After interpreting the test, participants were asked to reassess their intoxication and impairment levels, and were given a breath BAC test using a calibrated unit. The results revealed that although the majority of drinkers' were able to administer the GA test, their interpretations did not correspond with actual BACs. The interpretations of the GA test produced false-negatives, underestimating actual BACs. Drinkers perceived themselves to be less intoxicated, on average, after interpreting the GA test results. In conclusion, this research addresses potential pros and cons of providing BAC information to drinkers. It underscores the importance of testing BAC estimation tools under field conditions and the potential risks associated with tests that do not produce accurate results. 相似文献
303.
Carbon trading is no longer just theory. Infant markets already exist and, in 2002, they traded perhaps $10 million worth of emissions allowances. We estimate conservatively that, by 2010, the EU scheme will trade as much as $1 billion in allowances each year. The motor of the carbon markets is a worldwide effort to reduce emissions of greenhouse gases. Its most visible symbol is the Kyoto Protocol of 1997, formally known as the United Nations Framework Convention on Climate Change. Even if Kyoto is not ratified and, despite the US's decision to opt out of the treaty, the genie of greenhouse-gas reduction is out of the bottle. We believe that trading of greenhouse gases will be a real, day-to-day activity by 2010, almost certainly in Europe and probably in Canada and Japan. Carbon trading in these areas will affect the US, whether or not America sets up a programme of its own. The conclusion of this study is that industry should get involved in defining carbon trading-and now-to advance and defend their interests. Interest should be greatest among producers and users of the greenhouse gases other than carbon dioxide, namely methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulphur hexafluoride. 相似文献
304.
Photoperiodic time measurement is a well-documented adaptation of multicellular plants and animals to seasonal changes in the environment, but it is unclear whether unicellular organisms can exhibit bona fide photoperiodic responses. We demonstrate that the occurrence of zygospore germination of the unicellular alga Chlamydomonas is a genuine photoperiodic response. Germination efficiency is enhanced in long days as compared with short days. While the total amount of light exposure influences the efficiency of germination, the photoperiod is a significant cue for germination. The developmental stage that senses the photoperiod is just prior to mating and during the first days of zygospore development, so there may be a critical window of zygospore maturation that is regulated by photoperiod. Because zygospores are resistant to freezing injury, whereas vegetative cells are not, it is likely that the suppression of germination by short days is an adaptive response for overwintering of Chlamydomonas. Therefore, Chlamydomonas is a single-celled organism that is capable of photoperiodic responses. 相似文献
305.
Mallawaarachchi T Blamey RK Morrison MD Johnson AK Bennett JW 《Journal of environmental management》2001,62(3):301-316
Choice modelling is an emerging approach to estimating the non-use values of environmental services with multiple attributes. In this paper, results are reported of a choice modelling study conducted in the Herbert River District of North Queensland to estimate the value placed on the protection of natural vegetation in areas suitable for cane production by the local community. Resource use options that vary in the level of environmental protection and the level of agricultural production were presented as a series of choice sets and respondents were asked to choose among a set of three discrete alternatives in a given choice set. The alternatives in each choice set were described by four attributes, pertaining to the area of teatree woodlands, the area of vegetation along rivers and in wetlands, regional income from cane production, and an environmental levy. The responses were analysed together with socio-economic data using a nested-logit discrete-choice model to estimate the community willingness-to-pay for the protection of natural vegetation. The results indicate that the environmental values of wetlands are comparable to returns from commercial production of sugar cane and that the values of teatree woodlands are comparable to returns from extensive grazing. It is argued that land allocation policies should recognise these values in tandem with commercial benefits of production to ensure that resources are used more efficiently. 相似文献
306.
A small (1 km2) salt-affected stream drainage on the High Plains north of Denver, Colorado was sampled to determine the near-surface dispersion of soluble salts and metals from low-sulfur coal mining waste (spoil). Surface waters collected along the 0.8-km stream reach, and aqueous leachates of spoil and naturally saline local soil, were analyzed for chemical constituents and sulfur isotopes. In this semiarid setting with abundant carbonate-bearing surficial sediments, the limited, mildly acidic drainage from the spoil pile is quickly neutralized, restricting the mobility of many elements. However, some spoil-derived constituents were clearly traceable within the upper 0.4 km of the stream reach. Spoil leachates and surface water near the spoil pile have distinctive compositions of major anions and cations, and elevated levels of dissolved nitrate compared with downstream waters. Spoil-derived sulfate was traceable because it has generally positive values of delta34S that contrasted with generally negative values of delta34S in soil leachates and evaporite salts from the surrounding area. Spatial-chemical sampling of surface water showed an abrupt increase in dissolved U, Se, B, Li, and Mn in the lower 0.4 km of the stream reach where shallow ground water from surrounding irrigated fields contributed to surface flow. The downstream evolution of surface water chemistry and sulfur isotopic composition is consistent with mixing between spoil-affected upstream water and irrigation-return water. The methods described should be applicable at other sites in similar settings where the environmental effect of low-sulfur coal mining waste must be assessed and where access to samples of shallow ground water is limited. 相似文献
307.
K. Abbaspour V. Matta P. Huggenberger C. A. Johnson 《Journal of contaminant hydrology》2000,40(4):196
The investigation of contaminated sites is usually a long and expensive process. It is therefore desirable to use a combination of methodologies in an integrative approach that can reduce redundant information gathering. The objective of this study was to examine the usefulness of 2 non-intrusive exploration techniques in a contaminated site investigation. Borehole positioning based on geophysical measurements was compared to positioning based on the Bayesian expert system for flow-field modeling. The goal set at the field site was the assessment of the type and load of contaminants transported from the landfill site to the adjacent aquifer and the extent of leachate plumes within the groundwater. The two methods made different demands on information gathering and were found to be complementary. The geophysical approach focused attention on the waste compartments at the site and on mixing plumes in the adjacent aquifer but could not, without prior information, provided information on the flow field. The Bayesian approach to flow-field modeling determined areas of greatest model uncertainty at the model boundaries. The model highlighted areas of greatest uncertainty that might otherwise have been overlooked and provided information on the most likely mean direction of the leachate plumes. It was concluded that both methods contribute to a site investigation and should be used before additional drilling is carried out. 相似文献
308.
Geochemical mapping is a technique rooted in mineral exploration but has now found worldwide application in studies of the
urban environment. Such studies, involving multidisciplinary teams including geochemists, have to present their results in
a way that nongeochemists can comprehend. A legislatively driven demand for urban geochemical data in connection with the
need to identify contaminated land and subsequent health risk assessments has given rise to a greater worldwide interest in
the urban geochemical environment. Herein, the aims and objectives of some urban studies are reviewed and commonly used terms
such as baseline and background are defined. Geochemists need to better consider what is meant by the term urban. Whilst the
unique make up of every city precludes a single recommended approach to a geochemical mapping strategy, more should be done
to standardise the sampling and analytical methods. How (from a strategic and presentational point of view) and why we do
geochemical mapping studies is discussed.
相似文献
Christopher C. JohnsonEmail: |
309.
Johnson DL 《Environmental geochemistry and health》2008,30(6):589-596
This work introduces a spatially resolved quantitative model, based on conservation of mass and first order transfer kinetics,
for following the transport and redistribution of outdoor soil to, and within, the indoor environment by track-in on footwear.
Implementations of the DIRT model examined the influence of room size, rug area and location, shoe size, and mass transfer
coefficients for smooth and carpeted floor surfaces using the ratio of mass loading on carpeted to smooth floor surfaces as
a performance metric. Results showed that in the limit for large numbers of random steps the dual aspects of deposition to
and track-off from the carpets govern this ratio. Using recently obtained experimental measurements, historic transport and
distribution parameters, cleaning efficiencies for the different floor surfaces, and indoor dust deposition rates to provide
model boundary conditions, DIRT predicts realistic floor surface loadings. The spatio-temporal variability in model predictions
agrees with field observations and suggests that floor surface dust loadings are constantly in flux; steady state distributions
are hardly, if ever, achieved.
A contribution from ESF Center for the Urban Environment. 相似文献
310.
Within-nest temporal polyethism in the honey bee 总被引:1,自引:1,他引:0
Brian R. Johnson 《Behavioral ecology and sociobiology》2008,62(5):777-784
A well-regulated division of labor has been one of the core adaptations leading to the success of the social insects. Honeybee
division of labor has been classically viewed as a sequence of age-related changes in task performance. Kolmes questioned
this view arguing that his studies did not support the existence of any age-related within-nest specialization. To resolve
this controversy, Kolmes and Seeley conducted a joint study with mixed results. They found support for a cell cleaning caste,
but diverged on whether their results supported distinct nursing and middle age castes. In this paper, I follow up on their
work to resolve the question of caste number in within-nest honey bees. To determine whether nurses (typically aged 4–12 days)
and middle-aged bees (aged 12–20 days) have distinct task repertoires, I conducted focal animal observations on a large number
of workers in both age groups working within the same nests at the same time. The results support their being two castes of
within-nest bees. Young bees specialized on brood care tasks, while middle-aged bees specialized on nectar processing and
nest maintenance. Middle-aged bees were observed caring for brood in less than 1% of the observations. Moreover, both castes
exhibited movement patterns that correspond to the traditional view that nurses stay within the broodnest, while middle-aged
bees move around a great deal in search of work throughout the nest. A review of studies conducted since the debate of Seeley
and Kolmes supports the reliability of these results. This work has relevance for proximate models of temporal polyethism,
as it is often assumed by such models that there is only one within-nest caste in the honeybee. 相似文献