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981.
F. A. Norris J. W. Noling R. L. Jones S. D. Kirkland A. J. Overman C. D. Stanley 《Journal of contaminant hydrology》1991,8(3-4)
Unsaturated- and saturated-zone field studies were conducted under two different agricultural conditions in Florida, U.S.A., to measure the movement and degradation of ethoprop.When ethoprop was applied to a sand soil in an orange grove located on the Florida central ridge, soil residues declined with a half-life of 13 days to near the limit of detection (0.01 μg g−1 within 2 months. Ethoprop residues were generally contained in the upper 2 m of soil. Although low levels of ethoprop were found in four groundwater samples within the first 3 months after application, the cause of these isolated and transient residues could not be determined. The data show that there was no widespread plume of ethoprop residues beneath or downgradient from the treated area.On a flatwood soil on the west coast of Florida, ethoprop was incorporated into raised beds and protected by a plastic mulch in which tomatoes were grown. When the plastic mulch was present, ethoprop soil residues declined with a half-life of 40 days and were confined to the upper 0.3 m of soil. After the mulch was removed at crop harvest, the remaining ethoprop dissipated with a half-life of 12 days. Groundwater residues in excess of 1 μg L−1 were confined to a single sample collected after the well had been damaged during a rototilling operation. Resides of < 1 μg L−1 were present in three later samples from this well. At the sampling interval where the highest residues were detected in the damaged well, ethoprop residues of < 1 μg L−1 were also found in three other wells but no residues were detected in these wells in later samples. 相似文献
982.
Astrid Wetzel Gabriela Klante D. Werner 《Umweltwissenschaften und Schadstoff-Forschung》1991,3(5):266-271
Im Zusammenhang mit der Umweltchemikalienprüfung und der Untersuchung und Kontrolle kontaminierter B?den besteht gro?er Bedarf
an Testverfahren mit h?heren Pflanzen, die schnell, einfach und preisgünstig durchzuführen sind und bereits bestehende Testverfahren
nach OECD- und BBA-Richtlinien sinnvoll erg?nzen k?nnen. Dieser Beitrag stellt einen Biotoxizit?tstest vor, der die Nodulation
in der Leguminosen-Kn?llchen-Symbiose als sensiblen Wirkungsparameter für die Belastung mit polyzyklischen aromatischen Kohlenwasserstoffen
(PAK) benutzt. Fremdstoff, Pflanze und Mikroorganismus werden dabei auf einer festen Matrix in Kontakt miteinander gebracht;
das axenische System erlaubt die Untersuchung der Fremdstoffwirkung sowohl auf den Gesamtorganismus Pflanze, als auch auf
die Interaktion von Pflanze und Mikroorganismus (Kn?llchenbildung). In Dose-Response-Versuchen zeigte sich der Wirkungsparameter
Nodulation, gemessen als Anzahl Wurzelkn?llchen pro Pflanze, sensibler als andere pflanzliche Wachstumsparameter.
There is great need for toxicity tests with higher plants for the investigation and monitoring of chemicals in the environment
— especially for tests which are quick, easy, and inexpensive. Such tests should add to and improve current guidelines, e.g.,
OECD- and BBA-Guidelines. This article describes the nodulation of leguminous plants withRhizobium bacteria used in a bioassay with polycyclic aromatic hydrocarbons (PAH). Plants growing on a solid medium were exposed simultaneously
to bacteria and PAH. This axenic culture system allows to observe the impact of PAH on plant growth and the interaction between
plant and bacteria (nodulation). Dose-response-experiments indicated that nodulation measured as number of nodules per plant,
was more sensitive to the inhibition by PAH than other plant growth parameters. 相似文献
983.
R. Haas I. Schreiber Petra Kopecz G. Stork 《Umweltwissenschaften und Schadstoff-Forschung》1991,3(2):70-73
Die Ergebnisse der Untersuchung von Wasserproben aus dem Einflu?ereich der Rüstungsaltlast „Dethlinger Teich“ bei Munster/Niedersachsen
werden dargestellt und bewertet. Von mehr als 50 untersuchten spezifischen Substanzen wurden Arsenkampfstoffe als Hauptkontaminanten
erkannt. Im Rahmen der Gef?hrdungsabsch?tzung wird hier erstmals eine Analysenmethode zur Unterscheidung zwischen anorganisch
und organisch gebundenem Arsen vorgestellt.
Groundwater analyses in the area of the former munitions depository (World War II) „Dethlinger Teich“ near Munster/Niedersachsen
were evaluated. Results from 50 different chemical substances showed that arsenic compounds are the main contaminating chemicals.
A new method has been developed to distinguish between morganically- and organically bound compounds. This differentiation
is required for risk assessment and evaluation. Also, the relationship of chemical structure and physiological effects in
organo arsenic compounds is described. 相似文献
984.
C. M. Linklater Y. Albinsson W. R. Alexander I. Casas I. G. McKinley P. Sellin 《Journal of contaminant hydrology》1996,21(1-4)
Current design concepts for low-/intermediate-level radioactive waste disposal in many countries involve emplacement underground in a cementitious repository. The highly alkaline groundwaters at Maqarin, Jordan, are a good analogue for the cementitious pore waters that will be present within such a repository. A geochemical modelling study of these groundwaters has been carried out in order to test the applicability of equilibrium models in geochemical programs and their associated thermodynamic databases in such hyperalkaline conditions. This was achieved by comparison of elemental solubilities and speciations predicted by the programs with observations in the natural system. Five organisations took part in the study: AEA Technology, U.K.; Chalmers University of Technology, Sweden; MBT Tecnología Ambiental, Spain; Nagra, Switzerland; and SKB, Sweden. The modelling study was coordinated by the University of Berne.The results of the study showed good agreement between the predictions of the programs employed. Comparison of the observed solids with those predicted by the models has allowed limited validation of the databases. The results for U and Se are presented here. 相似文献
985.
986.
987.
988.
The concept of “Environmental Hazard Profile” developed at this institute has been tested with 100 14C-labelled organic compounds. Concentration factors in activated sludge, in algae and fish were determined. The microbial degradation of the chemicals to CO2 in activated sludge and the decomposition to CO2 under artificial light were determined. Ranking of compounds is given in the order of falling concentration factors and accumulation in rats respectively, and decreasing rates of decomposition. Relationship between chemical structure and accumulative and degradative behaviours is demonstrated using some selected groups of chemicals, such as benzenes, phenols, biphenyls and polyaromatic hydrocarbons. Correlations between the octanol/water partition coefficient, concentration factors and rates of decomposition could be established. Evaluation of test compounds was possible using hazard profiles obtained by the sum of single test results. 相似文献
989.
Washing as a remediation technology applicable in soils heavily polluted by mining-metallurgical activities 总被引:7,自引:0,他引:7
A permanent solution in order to remediate a heavily contaminated soil is washing it utilizing the appropriate reagents. The study presented in this paper deals with the washing of a soil highly polluted by mining and metallurgical activities. Pollution consists of slags, sulphur compound waste and various low grade lead condensates, all rich in heavy metals and metalloids (Pb, As, Cu, Zn, Mn and Fe). Soil was washed with deionized water, 6, 3, 2 and 1 M HCl, 6 M H(2)SO(4), 6 M HNO(3) and 0.1 M Na(2)EDTA. High extraction efficiency was achieved with respect to hydrochloric acid even at the lowest concentration; the solubility of pollutants in nitric acid was low, while sulphuric acid was proven to be problematic with respect to lead. Mobilization of metals and metalloids under DI water effect was minimal indicating that the elements fraction that is weakly bound to soil particles is insignificant. Furthermore, a kinetic study was undertaken, utilizing 1 M HCl and 0.1 M Na(2)EDTA. Results illustrated that 1 M HCl was more effective for intermediate mixing times (up to 4 h) while 0.1 M Na(2)EDTA was better applicable to short mixing times (<1 h) and low pH values (pH < 7.1). 1 M HCl was proven to be very effective for the removal of pollutants from contaminated soil but the high metal content of the resulting solution necessitates further treatment for the retention of metals. 相似文献
990.
The performance of three statistical methods: time-series, multiple linear regression and feedforward artificial neural networks models were compared to predict the daily mean ozone concentrations. The study here reported was based on data from one urban site with traffic influences and one rural background site. The studies were performed for the year 2002 and the respective four trimesters separately. In the multiple linear regression and feedforward artificial neural network models, the concentrations of ozone, the concentrations of its precursors (nitrogen oxides) and some meteorological variables for one and two days before the prediction day were used as predictors. For the application of these models in the validation step, the inputs of ozone concentration for one and two days before were replaced by the ozone concentrations predicted by the models. The results showed that time-series modelling was not profitable. In the development step, similar performances were obtained with multiple linear regression and feedforward artificial neural network. Better performance indexes were achieved with feedforward artificial neural network models in validation step. Concluding, feedforward artificial neural network models were more efficient to predict ozone concentrations. 相似文献