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91.
Yu Y Schleicher N Norra S Fricker M Dietze V Kaminski U Cen K Stüben D 《Journal of environmental monitoring : JEM》2011,13(2):334-346
Systematic sampling and analysis were performed to investigate the dynamics and the origin of suspended particulate matter smaller than 2.5 μm in diameter (PM(2.5)), in Beijing, China from 2005 to 2008. Identifying the source of PM(2.5) was the main goal of this project, which was funded by the German Research Foundation (DFG). The concentrations of 19 elements, black carbon (BC) and the total mass in 158 weekly PM(2.5) samples were measured. The statistical evaluation of the data from factor analysis (FA) identifies four main sources responsible for PM(2.5) in Beijing: (1) a combination of long-range transport geogenic soil particles, geogenic-like particles from construction sites and the anthropogenic emissions from steel factories; (2) road traffic, industry emissions and domestic heating; (3) local re-suspended soil particles; (4) re-suspended particles from refuse disposal/landfills and uncontrolled dumped waste. Special attention has been paid to seven high concentration "episodes", which were further analyzed by FA, enrichment factor analysis (EF), elemental signatures and backward-trajectory analysis. These results suggest that long-range transport soil particles contribute much to the high concentration of PM(2.5) during dust days. This is supported by mineral analysis which showed a clear imprint of component in PM(2.5). Furthermore, the ratios of Mg/Al have been proved to be a good signature to trace back different source areas. The Pb/Ti ratio allows the distinction between periods of predominant anthropogenic and geogenic sources during high concentration episodes. Backward-trajectory analysis clearly shows the origins of these episodes, which partly corroborate the FA and EF results. This study is only a small contribution to the understanding of the meteorological and source driven dynamics of PM(2.5) concentrations. 相似文献
92.
Clarifying conditions and decision points for mediational type inferences in Organizational Behavior
Although mediational designs and analyses are quite popular in Organizational Behavior research, there is much confusion surrounding the basis of causal inferences. We review theoretical, research design, and construct validity issues that are important for drawing inferences from mediational analyses. We then distinguish between indirect effects, and partial and full mediational hypotheses and outline decision points for drawing inferences of each type. An empirical illustration is provided using structural equation modeling (SEM) techniques, and we discuss extensions and directions for future research. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
93.
Environment plays a major role for determining the kind of courtship behaviours or alternative mating tactics employed, but
the effect of physical variables on fitness has received little attention. The Alpine newt courts during both day and night
times and exhibits a complex suite of behaviours involving olfactory, visual and tactile cues. Displaying in both dark and
light conditions may increase the number of mating opportunities and alleviate predation risk, but the frequency and efficacy
of the various tactics deployed may vary across light conditions, leading males to vary their use of these tactics across
different light regimes. To test this hypothesis, we video-recorded sexual encounters at two light intensities in a controlled
experimental design. When courting in the dark, males used comparatively more olfactory rather than visual displays. They
also relied more on positive feedback from the female before releasing a spermatophore for her to pick up. The particular
mix of tactics used under each light condition is likely to be adaptive because in the dark (1) visual communication is hampered,
making olfactory displays possibly more effective and (2) males depositing spermatophores are more likely to lose fertilizations
to competitors. Mating in light and dark conditions has similar reproductive payoffs, which shows that displaying in the dark
is not detrimental and may even be advantageous if predation risk is reduced at night. These results confirm the importance
of taking into account physical variables to understand the evolution of sexual communication in animals. 相似文献
94.
Julien Guigue Olivier Mathieu Jean Lévêque Sophie Denimal Marc Steinmann Marie-Jeanne Milloux Hervé Grisey 《Waste management (New York, N.Y.)》2013,33(11):2287-2295
This study characterises the sediment dredged from a lagooning system composed of a settling pond and three lagoons that receive leachates from a municipal solid waste (MSW) landfill in France. Organic carbon, carbonate, iron oxyhydroxides, copper (Cu) and zinc (Zn) concentrations were measured in the sediment collected from upstream to downstream in the lagooning system. In order to complete our investigation of sedimentation mechanisms, leachates were sampled in both dry (spring) and wet (winter) seasonal conditions. Precipitation of calcite and amorphous Fe-oxyhydroxides and sedimentation of organic matter occurred in the settling pond. Since different distributions of Zn and Cu concentrations are measured in sediment samples collected downstream in the lagooning system, it is suggested that these elements were not distributed in a similar way in the leachate fractions during the first stage of treatment in the settling pond, so that their sedimentation dynamics in the lagooning system differ. In the lagoons, it was found that organic carbon plays a major role in Cu and Zn mobility and trapping. The presence of macrophytes along the edges provided an input of organic matter that enhanced Cu and Zn scavenging. This edge effect resulted in a two-fold increase in Cu and Zn concentrations in the sediment deposited near the banks of the lagoons, thus confirming the importance of vegetation for the retention of Cu and Zn in lagooning systems. 相似文献
95.
Mathieu O Hénault C Lévêque J Baujard E Milloux MJ Andreux F 《Environmental pollution (Barking, Essex : 1987)》2006,144(3):933-940
Microbial transformations of nitrification and denitrification are the main sources of nitrous oxide (N2O) from soils. Relative contributions of both processes to N2O emissions were estimated on an agricultural soil using 15N isotope tracers (15NH4+ or 15NO3-), for a 10-day batch experiment. Under unsaturated and saturated conditions, both processes were significantly involved in N2O production. Under unsaturated conditions, 60% of N-N2O came from nitrification, while denitrification contributed around 85-90% under saturated conditions. Estimated nitrification rates were not significantly different whatever the soil moisture content, whereas the proportion of nitrified N emitted as N2O changed from 0.13 to 2.32%. In coherence with previous studies, we interpreted this high value as resulting from the decrease in O2 availability through the increase in soil moisture content. It thus appears that, under limiting aeration conditions, some values for N2O emissions through nitrification could be underestimated. 相似文献
96.
97.
98.
Mathieu Lihoreau Jean-Louis Deneubourg Colette Rivault 《Behavioral ecology and sociobiology》2010,64(10):1577-1587
Group foraging by eusocial insects implies sophisticated recruitment processes that often result in collective decisions to
exploit the most profitable sources. These advanced levels of cooperation, however, remain limited to a small range of species,
and we still know little about the mechanisms underlying group foraging behaviours in the great mass of animals exhibiting
lower levels of social complexity. In this paper, we report, for the first time in a gregarious insect, the cockroach Blattella germanica (L.), a collective foraging decision whereby the selection of food sources is reached without requiring active recruitment.
Groups of cockroaches given a binary choice between identical food sources exhibited exploitation asymmetries whose amplitude
increases with group size. By coupling behavioural observations to computer simulations, we demonstrate that selection of
food sources relies uniquely on a retention effect of feeding individuals on newcomers without comparison between available
opportunities. This self-organised pattern presents similarities with the foraging dynamics of eusocial species, thus stressing
the generic dimension of collective decision-making mechanisms based on social amplification rules despite fundamental differences
in recruitment processes. We hypothesise that such parsimony could apply to a wide range of species and help understand the
emergence of collective behaviours in simple social systems. 相似文献
99.
Gilles Morin Jean Gekas Philippe Naepels Jean Gondry Bernard Devauchelle Sylvie Testelin Henri Sevestre François Thépôt Michèle Mathieu 《黑龙江环境通报》2001,21(10):890-893
Ultrasonography in a female fetus revealed cystic cervical hygroma, severe micrognathia, and vertebral and upper limb anomalies suggestive of cerebro-costo-mandibular syndrome (CCMS) which was diagnosed ultrasonographically at 16 weeks' gestation. The father is affected and presents with a Pierre Robin sequence, short stature and typical costovertebral anomalies. CCMS is a rare and severe disorder. The high frequency of sporadic cases, vertical transmission, and the excess of sibs affected via horizontal transmission suggest dominant autosomal mutation with possible germinal mosaicism. The vertical familial case detailed in the present report is a reminder of the high risk when one parent or one sibling is affected and the extreme variability of phenotype and costal ossification. Early prenatal ultrasound diagnosis is possible in a severely affected fetus. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
100.
Mathieu Denoël Maryève Mathieu Pascal Poncin 《Behavioral ecology and sociobiology》2005,58(2):121-127
Temperature is expected to have an effect on the behavioral patterns of all organisms, especially ectotherms. However, although several studies focused on the effect of temperature on acoustic displays in both insects and anurans, almost nothing is known about how environmental temperature may affect ectotherm visual courtship displays and sexual performance. The purpose of this study was to determine the effect of environmental temperature on the sexual behavior of Alpine newts (Triturus alpestris). We subjected T. alpestris to two different temperatures in controlled laboratory conditions. Temperature had a major effect on both male and female behaviors: at low temperature, the frequencies of several displays, including tail-raising during sperm deposition, are lowered. This variation is caused indirectly by temperature because it is due to female responsiveness, which is temperature-dependent. However, the fanning movement of the males tail during its main courtship display is independent of female behavior: at lower temperatures, the tail beats at a lower rate, but for a longer time. The similar reproductive success (i.e. sperm transfer) at the two temperature ranges indicates that breeding in cold water is not costly but instead allows males and females to mate early in the season. This is particularly adaptive because, in many habitats, the reproductive period is shortened by drying or freezing conditions, which may impair survival of branchiate offspring. This study also demonstrates the necessity of considering environmental parameters when modeling optimality and characteristics of ectotherm behaviors.Communicated by W. Cooper 相似文献