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511.
Accurate methods quantifying whole landfill surface flux of methane are important for regulatory and research purposes. This paper presents the results from the analysis of chamber measurements utilizing geospatial techniques [kriging and inverse distance weighting (IDW)] to arrive at an estimation of the whole landfill surface flux from the spatially distributed chamber measurement points. The difficulties in utilizing these methods will be discussed. Methane flux was determined on approximately 20 m grid spacing and variogram analysis was performed in order to model spatial structure, which was used to estimate methane flux at unsampled locations through kriging. Our analysis indicates that while the semi-variogram model showed some spatial structure, IDW was a more accurate interpolation method for this particular site. This was seen in the comparison of the resulting contour maps. IDW, coupled with surface area algorithms to extract the total area of user defined contour intervals, provides a superior estimate of the methane flux as confirmed through the methane balance. It is critical that the results of the emissions estimates be viewed in light of the whole cell methane balance; otherwise, there is no rational check and balance system to validate the results. 相似文献
512.
Steven N. Chillrud Richard F. Bopp James M. Ross Damon A. Chaky Sidney Hemming Edward L. Shuster H. James Simpson Frank Estabrooks 《Water, Air, & Soil Pollution: Focus》2004,4(2-3):469-482
Radionuclide, radiogenic lead isotope and trace metal analyses on fine-grained sediment cores collected along 160 km of the upper and tidal Hudson River were used to examine temporal trends of contaminant loadings and to develop radiogenic lead isotopes both as a stratigraphic tool and as tracers for resolving decadal particle transport fluxes. Very large inputs of Cd, Sb, Pb, and Cr are evident in the sediment record, potentially from a single manufacturing facility. The total range in radiogenic lead isotope ratios observed in well-dated cores collected about 24 km downstream of the plant is large (e.g., maximum difference in 206Pb/207Pb is 10%), characterized by four major shifts occurring in the 1950s, 1960s, 1970s and 1980s. The upper Hudson signals in Cd and radiogenic lead isotopes were still evident in sediments collected 160 km downstream in the tidal Hudson. The large magnitude and abrupt shifts in radiogenic lead isotope ratios as a function of depth provide sensitive temporal constraints that complement information derived from radionuclide analyses to significantly improve the precision of dating assignments. Application of a simple dilution model to data from paired cores suggests much larger sediment inputs in one section of the river than previously reported, suggesting particle influxes to the Hudson have been underestimated. 相似文献
513.
The establishment of soil cleanup levels is a primary concern in site remediation projects. Soil cleanup levels provide targets that drive the remediation process from technology selection through closure. Several state regulatory agencies are currently in the process of developing scientifically based soil cleanup standards. The underlying premise in the derivation of such standards is to ensure that the site will not pose a threat to human health and the environment after remediation has been completed. To accomplish this, remediation project managers must consider several contaminant transport pathways. This article presents the salient features of a model named IMPACT, which was developed to assist in the derivation of soil cleanup levels. IMPACT considers the soil-to-groundwater pathway and predicts the cleanup levels in a contaminated soil layer in the vadose zone such that groundwater quality standards are met at any point in the aquifer. 相似文献
514.
Leonard G. Pearlstine Wiley M. Kitchens Pamela J. Latham Richard D. Bartleson 《Journal of the American Water Resources Association》1993,29(6):1009-1019
ABSTRACT: Construction of a tide gate at the mouth of the north channel of the Savannah River in Georgia has resulted in significant changes in salinities influencing marsh community changes. The tide gate is directly responsible for a 2 to 6 mile upstream displacement of salt water in the river. In the marsh, soil salinities ranged from 0.0 ppt at upstream sites to 12 ppt at downstream sites when the tide gate was in operation. Within two months of taking the tide gate out of operation, interstitial salinities at the downstream sites dropped to 4 ppt. Influences of the tide gate on marsh vegetation were modeled in a geographic information system. With the tide gate out of operation, the model predicts that freshwater marsh would increase in area by 340 percent. 相似文献
515.
Chaudri AM Allain CM Badawy SH Adams ML McGrath SP Chambers BJ 《Journal of environmental quality》2001,30(5):1575-1580
Grain Cd concentrations were determined in the wheat (Triticum aestivum L.) cultivars Soissons, Brigadier, and Hereward grown in 1994,1996, and 1999, respectively, in soils of a long-term field experiment to which sewage sludges contaminated with Zn, Cu, Ni, or Cr had previously been added. Soil pore water soluble Cd and free Cd2+ increased linearly with increasing total soil Cd (R2=0.82 and 0.84, respectively; P<0.001). Similarly, soil pore water free Cd2+ increased linearly with increasing soil pore water soluble Cd (R2=0.98; P<0.001). There was no evidence of a plateau in soil pore water Cd concentrations with increasing soil Cd concentrations. Grain Cd concentrations were significantly correlated with total soil Cd (P<0.001), soil pore water Cd (P<0.001), and free Cd2+ (P<0.001). A slight curvilinear relationship between grain Cd and soil Cd was apparent, but there was no plateau, even at the maximum soil Cd concentration of about 2.7 mg kg(-1). The relationship between soil pore water Cd and grain Cd was linear for all three cultivars. The slopes were in the order 1994 > 1996 > 1999, with more Cd being taken up into the grain by Soissons grown in 1994, and least by Hereward grown in 1999. For Soissons, Cd concentration in the grain greater than the EU limit (0.24 mg kg(-1) dry wt.) occurred at soil Cd less than the current UK limit of 3 mg kg(-1) for soils receiving sewage sludge. In contrast, for Brigadier and Hereward, grain Cd concentrations were near to and less than the EU limit, respectively, at soil Cd concentrations of 3 mg kg(-1). 相似文献
516.
Glyphosate-resistant (GR) soybean [Glycine max (L.) Merr.] expressing an insensitive 5-enolpyruvylshikimic acid-3-phosphate synthase (EPSPS) gene has revolutionized weed control in soybean production. The soybean nitrogen fixing symbiont, Bradyrhizobium japonicum, possesses a glyphosate-sensitive enzyme and upon exposure to glyphosate accumulates shikimic acid and hydroxybenzoic acids such as protocatechuic acid (PCA), accompanied with B. japonicum growth inhibition and death at high concentrations. In a series of greenhouse and field experiments, glyphosate inhibited nodulation and nodule leghemoglobin content of GR soybean. Glyphosate accumulated in nodules of field-grown GR soybean, but its effect on nitrogenase activity of GR soybean was inconsistent in field studies. In greenhouse studies, nitrogenase activity of GR soybean following glyphosate application was transiently inhibited especially in early growth stages, with the greatest inhibition occurring under moisture stress. Studies using bacteroid preparations showed that the level of glyphosate inhibition of bacteroid nitrogenase activity was related to in vitro glyphosate sensitivity of the B. japonicum strains. These studies indicate the potential for reduced nitrogen fixation in the GR soybean system; however, yield reductions due to this reduced N2 fixation in early stages of growth have not been demonstrated. 相似文献
517.
M. A. STYRIKOVICH 《Natural resources forum》1977,1(3):251-261
The author reviews general questions affecting energy projections and goes on to examine reserve forecasts for each type of energy. The last part of the paper considers consumption forecasts and makes an assessment of the likely situation in the year 2000. 相似文献
518.
Timing of manure application affects N leaching. This 3-yr study quantified N losses from liquid manure application on two soils, a Muskellunge clay loam and a Stafford loamy sand, as affected by cropping system and timing of application. Dairy manure was applied at an annual rate of 93 800 L ha(-1) on replicated drained plots under continuous maize (Zea mays L.) in early fall, late fall, early spring, and as a split application in early and late spring. Variable rates of supplemental sidedress N fertilizer were applied as needed. Manure was applied on orchardgrass (Dactylis glomerata L.) in split applications in early fall and late spring, and early and late spring, with supplemental N fertilizer topdressed as NH4NO3 in early spring at 75 kg N ha(-1). Drain water was sampled at least weekly when lines were flowing. Three-year FWM (flow-weighted mean) NO3-N concentrations on loamy sand soil averaged 2.5 times higher (12.7 mg L(-1)) than those on clay loam plots (5.2 mg L(-1)), and those for fall applications on maize-cropped land averaged >10 mg L(-1) on the clay loam and >20 mg L(-1) on the loamy sand. Nitrate-N concentrations among application seasons followed the pattern early fall > late fall > early spring = early + late spring. For grass, average NO3-N concentrations from manure application remained well below 10 mg L(-1). Fall manure applications on maize show high NO3-N leaching risks, especially on sandy soils, and manure applications on grass pose minimal leaching concern. 相似文献
519.
Miguel Delibes-Mateos Miguel ángel Farfán Jesús Olivero Ana Luz Márquez Juan Mario Vargas 《Environmental management》2009,43(6):1256-1268
Agricultural change has transformed large areas of traditional farming landscapes, leading to important changes in the species
community assemblages in most European countries. We suspect that the drastic changes in land-use that have occurred in Andalusia
(southern Spain) over recent decades, may have affected the distribution and abundance of game species in this region. This
article compares the distribution of the main game species in Andalusia during the 1960s and 1990s, using data from maps available
from the Mainland Spanish Fish, Game and National Parks Service and from recent datasets on hunting yield distributions, respectively.
Big-game and small-game species were significantly segregated in southern Spain during the 1990s, as two clearly independent
chorotypes (groups of species whose abundances are similarly distributed) were obtained from the classification analysis.
In contrast, big-game and small-game species were not significantly segregated several decades ago, when there was only one
chorotype consisting of small-game species and wild boar. The other three ungulates did not constitute a significant chorotype,
as they showed positive correlations with some species in the group mentioned above. These changes seem to be a consequence
of the transformations that have occurred in the Iberian Mediterranean landscape over the last few decades. The abandoning
of traditional activities, and the consequent formation of dense scrubland and woodland, has led to an expansion of big-game
species, and a decrease of small-game species in mountain areas. Moreover, agricultural intensification has apparently depleted
small-game species populations in some agricultural areas. On the other hand, the increasingly intensive hunting management
could be artificially boosting this segregation between small-game and big-game species. Our results suggest that the conservation
and regeneration of traditional agricultural landscapes (like those predominating in the 1960s) should be a priority for the
conservation of small-game species. 相似文献
520.
Excess crude protein (CP) in dairy cow diets is excreted mostly as urea nitrogen (N), which increases ammonia (NH) emissions from dairy farms and heightens human health and environmental concerns. Feeding less CP and more tannin to dairy cows may enhance feed N use and milk production, abate NH emissions, and conserve the fertilizer N value of manure. Lab-scale ventilated chambers were used to evaluate the impacts of CP and tannin feeding on slurry chemistry, NH emissions, and soil inorganic N levels after slurry application to a sandy loam soil and a silt loam soil. Slurry from lactating Holstein dairy cows (Bos taurus) fed two levels of dietary CP (low CP [LCP], 155 g kg; high CP [HCP], 168 g kg) each fed at four levels of dietary tannin extract, a mixture from red quebracho (Schinopsis lorentzii) and chestnut (Castanea sativa) trees (0 tannin [0T]; low tannin [LT], 4.5 g kg; medium tannin [MT], 9.0 g kg; and high tannin [HT], 18.0 g kg) were applied to soil-containing lab-scale chambers, and NH emissions were measured 1, 3, 6, 12, 24, 36, and 48 h after slurry application. Emissions from the HCP slurry were 1.53 to 2.57 times greater ( < 0.05) than from the LCP slurry. At trial's end (48 h), concentrations of inorganic N in soils were greater ( < 0.05) in HCP slurry-amended soils than in LCP slurry-amended soils. Emissions from HT slurry were 28 to 49% lower ( < 0.05) than emissions from 0T slurry, yet these differences did not affect soil inorganic N levels. Emissions from the sandy loam soil were 1.07 to 1.15 times greater ( < 0.05) than from silt loam soil, a result that decreased soil inorganic N in the sandy loam compared with the silt loam soil. Larger-scale and longer-term field trails are needed to ascertain the effectiveness of feeding tannin extracts to dairy cows in abating NH loss from land-applied slurry and the impact of tannin-containing slurry on soil N cycles. 相似文献