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371.
Brooks MC Annable MD Rao PS Hatfield K Jawitz JW Wise WR Wood AL Enfield CG 《Journal of contaminant hydrology》2002,59(3-4):187-210
The partitioning tracer technique for dense nonaqueous phase liquid (DNAPL) characterization was evaluated in an isolated test cell, in which controlled releases of perchloroethylene (PCE) had occurred. Four partitioning tracer tests were conducted, two using an inverted, double five-spot pumping pattern, and two using vertical circulation wells. Two of the four tests were conducted prior to remedial activities, and two were conducted after. Each test was conducted as a "blind test" where researchers conducting the partitioning tracer tests had no knowledge of the volume, method of release, nor resulting spatial distribution of DNAPL. Multiple partitioning tracers were used in each test, and the DNAPL volume estimates varied significantly within each test based on the different partitioning tracers. The tracers with large partitioning coefficients generally predicted a smaller volume of PCE than that expected based on the actual release volume. However, these predictions were made for low DNAPL saturations (average saturation was approximately 0.003), under conditions near the limits of the method's application. Furthermore, there were several factors that may have hindered prediction accuracy, including tracer degradation and remedial fluid interference. 相似文献
372.
K. Shankar Rao 《Water, Air, & Soil Pollution: Focus》2002,2(5-6):261-277
The formulations and evaluation of ROADWAY-2, a near-highway pollutant dispersion model, are described. This model incorporates vehicle wake parameterizations derived from canopy flow theory and wind tunnel measurements. The atmospheric velocity and turbulence fields are adjusted to account for velocity-deficit and turbulence production in vehicle wakes. A turbulent kinetic energy closure model of the atmospheric boundary layer is used to derive the mean velocity, temperature, and turbulence profiles from input meteorological data. ROADWAY-2 has been evaluated using SF6 tracer data from General Motors Sulfate Dispersion Experiment. The model evaluationresults are presented and discussed. 相似文献
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K N Chetty D S Subba Rao L Drummond D Desaiah 《Journal of environmental science and health. Part. B》1979,14(5):525-544
The immuno-biochemical effects of cobaltous chloride in rats receiving iron-sufficient and deficient diets were investigated. Rats receiving 100 ppm or more cobalt showed a significant reduction in thymus and body weights along with a marked decrease in hemoglobin, hematocrit, sheep agglutinins and plaque forming cells. These effects were more pronounced in rats receiving cobalt mixed with iron-deficient diet than those fed on iron-sufficient diet. The Na+-K+ and mitochondrial (Oligomycin-sensitive) Mg2+ATPase activities in brain and liver of rats fed with iron-deficient diets were decreased significantly. However, the ATPase activities in these tissues from rats fed with cobalt mixed with iron-sufficient diets were not altered. 相似文献
375.
The growth of Anabaena and Aulosira fertilissima was adversely affected by endosulfan even at 1 microg ml(-1). The inhibition was significantly above 50% at 20 microg ml(-1) throughout the incubation. Anabaena survived up to 500 microg ml(-1) of malathion, but was completely bleached in the presence of 50 microg ml(-1) of endosulfan. Aulosira was more sensitive to malathion than Anabaena and recovered to control levels only at 10 microg ml(-1). The morphology and hetercyst frequency were not altered in Anabaena. Aulosira cultures were dull brown in colour at 20 microg ml(-1) of endosulfan with the filaments clumping, instead of the usual mat formation. Both malathion and endosulfan considerably lowered (14)C uptake and nitrogenase activities in Aulosira. Nitrogen fixation was unaffected in Anabaena as the amounts of ethylene produced were equal to, or above, control levels. The impact of these insecticides on photosynthesis in Anabaena was only slight. 相似文献
376.
Teegavarapu R. Rao 《Marine Biology》1974,24(2):155-162
Effects of salinity on embryonic development and survival were determined for eggs and larvae of the California killifish Fundulus parvipinnis Girard. Incubation salinities over the range of 5 to 14 S produced the shortest incubation period, maximum yolk-conversion efficiency, largest larval size at hatching, and maximum viable hatch. Various morphometric measurements of the newly-hatched larvae were influenced significantly by incubation salinity. Fertilization salinity also effected certain development criteria; in general, lower fertilization salinities resulted in shorter incubation periods and larger larvae at hatching. A salinity range of 5 to 14 S is anggested as a physiological optimum, and the known freshwater affinity of the species suggests that an eventual freshwater colonization by the California killifish is possible.Based on a thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, University of California, Irvine. 相似文献
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379.
Biodegradable Soy-Based Plastics: Opportunities and Challenges 总被引:3,自引:0,他引:3
S. N. Swain S. M. Biswal P. K. Nanda Padma L. Nayak 《Journal of Polymers and the Environment》2004,12(1):35-42
Today's plastics are designed with little consideration for their ultimate disposability or the effect of the resources (feedstocks) used in making them. This has resulted in mounting worldwide concerns over the environmental consequences of such materials when they enter the mainstream after their intended uses. This led to the concept of designing and engineering new biodegradable materials–materials that have the performance characteristics of today's materials but that undergo biodegradation along with other organic waste to soil humic materials. Hence, the production of biodegradable materials from annually renewable agricultural feedstocks has attracted attention in recent years. Agricultural materials such as starches and proteins are biodegradable and environmentally friendly. Soybean is a good candidate for manufacturing a large number of chemicals, including biodegradable plastics, as it is abundantly available and cheap. Soy protein concentrate, isolate, or flakes could be compounded with synthetic biodegradable plastics such as polycaprolactone or poly (lactic acid) to make molded products or edible films or shopping bags and make the environment cleaner and greener. 相似文献
380.