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601.
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Robert K Hall Peter Husby Gary Wolinsky Olof Hansen Michiko Mares 《Environmental monitoring and assessment》1998,51(1-2):357-367
The Central Valley of California contains critical habitat for many aquatic and terrestrial biological resources. The purpose of this R-EMAP project was to assess the effects from a highly modified agriculturally dominated landuse area on the aquatic resources of the lower portion of the Central Valley watersheds. The study area is 24,346 mi2 and comprises the Sacramento Valley and San Joaquin Valley watersheds to the 1,000 ft. elevation contour. Populations of interest are man-made conveyances and wadeable natural streams. There are 40,756 miles of streams and constructed conveyances within the Central Valley as designated by RF3 database. Sample sites were selected to represent 14,399 miles of streams and sloughs, and 16,697 miles of constructed conveyances. 相似文献
604.
Kenneth Strzepek David Yates Gary Yohe Richard Tol Nicholas Mader 《Integrated Assessment》2001,2(3):139-157
A space of “not-implausible” scenarios for Egypt's future under climate change is defined along two dimensions. One depicts
representative climate change and climate variability scenarios that span the realm of possibility. Some would not be very
threatening. Others portend dramatic reductions in average flows into Lake Nassar and associated increases in the likelihood
of year to year shortfalls below critical coping thresholds; these would be extremely troublesome, especially if they were
cast in the context of increased political instability across the entire Nile Basin. Still others depict futures along which
relatively routine and relatively inexpensive adaptation might be anticipated. The ability to adapt to change and to cope
with more severe extremes would, however, be linked inexorably to the second set of social–political–economic scenarios. The
second dimension, defined as “anthropogenic” social/economic/political scenarios describe the holistic environment within
which the determinants of adaptive capacity for water management, agriculture, and coastal zone management must be assessed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
605.
606.
Gary C. White 《Environmental and Ecological Statistics》2008,15(1):89-99
Program MARK provides > 65 data types in a common configuration for the estimation of population parameters from mark-encounter
data. Encounter information from live captures, live resightings, and dead recoveries can be incorporated to estimate demographic
parameters. Available estimates include survival (S or ϕ), rate of population change (λ), transition rates between strata (Ψ), emigration and immigration rates, and population
size (N). Although N is the parameter most often desired by biologists, N is one of the most difficult parameters to estimate precisely without bias for a geographically and demographically closed
population. The set of closed population estimation models available in Program MARK incorporate time (t) and behavioral (b) variation, and individual heterogeneity (h) in the estimation of capture and recapture probabilities in a likelihood framework. The full range of models from M
0 (null model with all capture and recapture probabilities equal) to M
tbh
are possible, including the ability to include temporal, group, and individual covariates to model capture and recapture
probabilities. Both the full likelihood formulation of Otis et al. (1978) and the conditional model formulation of Huggins
(1989, 1991) and Alho (1990) are provided in Program MARK, and all of these models are incorporated into the robust design
(Kendall et al. 1995, 1997; Kendall and Nichols 1995) and robust-design multistrata (Hestbeck et al. 1991, Brownie et al.
1993) data types. Model selection is performed with AICc (Burnham and Anderson 2002) and model averaging (Burnham and Anderson
2002) is available in Program MARK to provide estimates of N with standard error that reflect model selection uncertainty. 相似文献
607.
The effects of learning versus outcome distal goals in conjunction with proximal goals were investigated in a laboratory setting using a class‐scheduling task. The participants (n = 96) needed to acquire knowledge in order to perform the task correctly. A ‘do your best’ outcome goal led to higher performance than the assignment of a specific, difficult outcome goal. However, the assignment of a specific, difficult learning goal led to higher performance than urging people to ‘do their best.’ Goal commitment was higher in the learning goal than in the outcome goal condition. The correlation between task‐relevant strategies discovered and performance was positive and significant. The number of task‐relevant strategies implemented by participants assigned a distal learning goal in conjunction with proximal goals was higher than in any other goal condition. Setting a distal outcome or learning goal that included proximal outcome goals, however, did not lead to higher performance than the setting of a distal outcome or learning goal alone. Self‐efficacy correlated significantly with performance, and this effect was mediated through strategy development. Furthermore, the discovery of task‐relevant strategies affected self‐efficacy through an increase in performance. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
608.
609.
Bhanukiran SUNKARA Yang SU Jingjing ZHAN Jibao HE Gary L. MCPHERSON Vijay T. JOHN 《Frontiers of Environmental Science & Engineering》2015,9(5):939
Iron-carbon (Fe-C) composite microspheres prepared through a facile aerosol-based process are effective remediation agents for the simultaneous adsorption and reduction of chlorinated hydrocarbons. Complete dechlorination was achieved for the class of chlorinated ethenes that include tetrachloroethylene (PCE), trichloroethylene (TCE), cis- and trans-1,2-dicloroethylene (c-DCE, t-DCE), 1,1-dichloroethylene (1,1-DCE) and, vinyl chloride (VC). The Fe-C particles potentially provides multi-functionality with requisite characteristics of adsorption, reaction, and transport for the effective in situ remediation of chlorinated hydrocarbons. The carbon support immobilizes the ferromagnetic iron nanoparticles onto its surface, thereby inhibiting aggregation. The adsorptive nature of the carbon support prevents the release of toxic intermediates such as the dichloroethylenes and vinyl chloride. The adsorption of chlorinated ethenes on the Fe-C composites is higher (>80%) than that of humic acid (<35%) and comparable to adsorption on commercial activated carbons (>90%). The aerosol-based process is an efficient method to prepare adsorptive-reactive composite particles in the optimal size range for transport through the porous media and as effective targeted delivery agents for the in situ remediation of soil and groundwater contaminants. 相似文献
610.
Natural attenuation of chlorinated ethene compounds: model development and field-scale application at the Dover site 总被引:1,自引:0,他引:1
T. Prabhakar Clement Christian D. Johnson Yunwei Sun Gary M. Klecka Craig Bartlett 《Journal of contaminant hydrology》2000,42(2-4)
A multi-dimensional and multi-species reactive transport model was developed to aid in the analysis of natural attenuation design at chlorinated solvent sites. The model can simulate several simultaneously occurring attenuation processes including aerobic and anaerobic biological degradation processes. The developed model was applied to analyze field-scale transport and biodegradation processes occurring at the Area-6 site in Dover Air Force Base, Delaware. The model was calibrated to field data collected at this site. The calibrated model reproduced the general groundwater flow patterns, and also, it successfully recreated the observed distribution of tetrachloroethene (PCE), trichloroethene (TCE), dichloroethylene (DCE), vinyl chloride (VC) and chloride plumes. Field-scale decay rates of these contaminant plumes were also estimated. The decay rates are within the range of values that were previously estimated based on lab-scale microcosm and field-scale transect analyses. Model simulation results indicated that the anaerobic degradation rate of TCE, source loading rate, and groundwater transport rate are the important model parameters. Sensitivity analysis of the model indicated that the shape and extent of the predicted TCE plume is most sensitive to transmissivity values. The total mass of the predicted TCE plume is most sensitive to TCE anaerobic degradation rates. The numerical model developed in this study is a useful engineering tool for integrating field-scale natural attenuation data within a rational modeling framework. The model results can be used for quantifying the relative importance of various simultaneously occurring natural attenuation processes. 相似文献