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51.
Henri E.Z. Tonnang Lev V. Nedorezov John O. Owino Horace Ochanda Bernhard Löhr 《Ecological modelling》2009
The performance of discrete mathematical models to describe the population dynamics of diamondback moth (DBM) (Plutella xylostella L.) and its parasitoid Diadegma semiclausum was investigated. The parameter values for several well-known models (Nicholson–Bailey, Hassell and Varley, Beddington, Free and Lawton, May, Holling type 2, 3 and Getz and Mills functional responses) were estimated. The models were tested on 20 consecutive sets of time series data collected at 14 days interval for pest and parasitoid populations obtained from a highland cabbage growing area in eastern Kenya. Model parameters were estimated from minimized squared difference between the numerical solution of the model equations and the empirical data using Powell's method. Maximum calculated DBM growth rates varied between 0.02 and 0.07. The carrying capacity determined at 16.5 DBM/plant by the Beddington et al. model was within the range of field data. However, all the estimated parameter values relating to the parasitoid, including the instantaneous searching rate (0.07–0.28), per capita searching efficiency (0.20–0.27), search time (5.20–5.33), handling time (0.77–0.90), and parasitism aggregation index (0.33), were well outside the range encountered empirically. All models evaluated for DBM under Durbin–Watson criteria, except the May model, were not autocorrelated with respect to residuals. In contrast, the criteria applied to the parasitoid residuals showed strong autocorrelations. Thus, these models failed to estimate parasitoid dynamics. We conclude that the interactions of the DBM with its parasitoid cannot be explained by any of the models tested. Two factors may be associated with this failure. First, the parasitoid in this integrated biological control system may not be playing a major role in regulating DBM population. Second, and perhaps more likely, poor correlations reflect gross inadequacies in the theoretical assumptions that underlie the existing models. 相似文献
52.
Thomas G. Reichenauer Sunil Panamulla Siripala Subasinghe Bernhard Wimmer 《Environmental geochemistry and health》2009,31(5):573-579
The tsunami disaster in the Indian Ocean in December 2004 caused devastation of agricultural soils by salt water over wide
areas. Many rice fields located close to the coast were affected by the flood of seawater. Electric conductivity (EC) of soils
in tsunami-affected rice fields was found to be higher compared to unaffected fields 2 years after the tsunami. Four soil
amendments (gypsum, dolomite, cinnamon ash and rice-husk-charcoal) were tested for their influence on improving the yield
parameters of rice grown in a tsunami-affected and a non-affected area. Yield parameters were compared with an untreated control
of the same cultivar (AT362) and with a salt resistant rice variety (AT354). The salt resistant variety had the highest grain
yield. The two amendments gypsum and rice-husk-charcoal led to an increase in grain yield compared to the untreated control,
whereas dolomite and cinnamon ash had no significant effect on grain yield. 相似文献
53.
Bernhard Rappenglück Heinrich Reitmayer Peter Fabian 《Environmental science and pollution research international》2000,7(4):211-218
Measurements of nitrogen dioxide, ozone and, for the first time, on-line, nonmethane hydrocarbons with a quasicontinuous gaschromatographic/flame ionization technique were performed on a manned hydrogen-gas balloon platform. A cycle time of 10 min allowed the determination of nonmethane hydrocarbons in the carbon number range of C4-C10 with a detection limit of 10 pptv. In addition, meteorological parameters (atmospheric pressure, temperature, humidity) along with GPS-data (global positioning system) was accomplished during the balloon flights. Balloon measurements of trace compounds provide valuable information about photochemical processes in the boundary layer since gas ballooning offers the only technique that stays in the same air parcel along Langrangian trajectories. In addition, gas ballooning represents a unique tool to elucidate micrometeorological observations such as atmospheric stability oscillations and local wind fields. 相似文献
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Interpreting the functional content of a given genomic sequence is one of the central challenges of biology today. Perhaps the most promising approach to this problem is based on the comparative method of classic biology in the modern guise of sequence comparison. For instance, protein-coding regions tend to be conserved between species. Hence, a simple method for distinguishing a functional exon from the chance absence of stop codons is to investigate its homologue from closely related species. Predicting regulatory elements is even more difficult than exon prediction, but again, comparisons pinpointing conserved sequence motifs upstream of translation start sites are helping to unravel gene regulatory networks. In addition to interspecific studies, intraspecific sequence comparison yields insights into the evolutionary forces that have acted on a species in the past. Of particular interest here is the identification of selection events such as selective sweeps. Both intra- and interspecific sequence comparisons are based on a variety of computational methods, including alignment, phylogenetic reconstruction, and coalescent theory. This article surveys the biology and the central computational ideas applied in recent comparative genomics projects. We argue that the most fruitful method of understanding the functional content of genomes is to study them in the context of related genomic sequences. In particular, such a study may reveal selection, a fundamental pointer to biological relevance. 相似文献
60.
Sven Scheil Guido Baumgarten Bernhard Reiter Stefan Schwartz Jan Oliver Wagner Stefan Trapp Michael Matthies 《Environmental science and pollution research international》1995,2(4):238-241
The model system CemoS1 (Chemical Exposure Model System) was developed for the exposure prediction of hazardous chemicals released to the environment.
Eight different models were implemented involving chemicals fate simulation in air, water, soil and plants after continuous
or single emissions from point and diffuse sources. Scenario studies are supported by a substance and an environmental data
base. All input data are checked on their plausibility. Substance and environmental process estimation functions facilitate
generic model calculations. CemoS is implemented in a modular structure using object-oriented programming.
e-mail: cemos@aphrodite.mathematik.uni-osnabrueck.de 相似文献