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331.
332.
Marc-Antoine Sanchez Simon-Pierre Corcostégui Charles-Arnaud De Broucker Olivier Cabre Stéphanie Watier-Grillot Sylvie Perelle Katia Ambert-Balay Vincent Pommier de Santi 《Food and environmental virology》2017,9(2):234-237
In February 2016, an outbreak of gastroenteritis occurred in a French military unit located in Poitiers, France. Attack rate was of 34% (103/300). A case–control study identified association between illness and cake consumption. Stool samples were tested positive for Norovirus GII.17 for one patient and one post-symptomatic food worker (FW). The FW presented vomiting one day before cake preparation. The NoV strain was probably spread through food worker hand contact. Prevention of Norovirus foodborne outbreaks implies new guidelines for FWs management in France and Europe. 相似文献
333.
Amélia Viricel Allan E. Strand Patricia E. Rosel Vincent Ridoux Pascale Garcia 《Behavioral ecology and sociobiology》2008,63(2):173-185
Compared to terrestrial mammals, little is known of cetacean social systems as they are generally less accessible to behavioral
investigations due to their aquatic environment. The present study investigates group structure of the pelagic common dolphin,
Delphinus delphis, using genetic markers. Tissue samples from 52 individuals representing a recent live mass-stranding event were compared
to 42 single strandings taken from presumably different groups. The mass-stranding event occurred in 2002 on the French coast
of the English Channel, whereas the single strandings were collected between 1993 and 2003 along the western coast of France
(Bay of Biscay and English Channel). Analysis of mitochondrial DNA control region sequences indicated that genetic variability
within the mass-stranded pod was similar to variability observed in single strandings. The mass-stranded group was composed
of 41 different mitochondrial haplotypes or matrilines while the single strandings revealed 29 different haplotypes. Analysis
of 11 microsatellite loci revealed that average relatedness of the mass-stranded pod was not different from average relatedness
among all single strandings suggesting that individuals within the group had no closer kin relationships than animals taken
from presumably different groups. These results do not support a matriarchal system and suggest that common dolphins constituting
a pod are not necessarily genetically related. 相似文献
334.
Vincent Mirabet Pierre Fréon Christophe Lett 《Behavioral ecology and sociobiology》2008,63(2):159-171
There is evidence that individuals in animal groups benefit from the presence of knowledgeable group members in different
ways. Experiments and computer simulations have shown that a few individuals within a group can lead others, for a precise
task and at a specific moment. As a group travels, different individuals possessing a particular knowledge may act as temporary
leaders, so that the group will, as a whole, follow their behaviour. In this paper, we use a model to study different factors
influencing group response to temporary leadership. The model is based on four individual behaviours. Three of those, attraction,
repulsion, and alignment, are shared by all individuals. The last one, attraction toward the source of a stimulus, concerns
only a fraction of the group members. We explore the influence of group size, proportion of stimulated individuals, number
of influential neighbours, and intensity of the attraction to the source of the stimulus, on the proportion of the group reaching
this source. Special attention is given to the simulation of large group size, close to those observed in nature. Groups of
100, 400 and 900 individuals are currently simulated, and up to 8,000 in one experiment. We show that more stimulated individuals
and a larger group size both induce the arrival of a larger fraction of the group. The number of influential neighbours and
the intensity of the stimulus have a non-linear influence on the proportion of the group arrival, displaying first a positive
relationship and then, above a given threshold, a negative one. We conclude that an intermediate level of group cohesion provides
optimal transfer information from knowledgeable to naive individuals. 相似文献
335.
From open access to access by all: restating challenges in designing groundwater management in Andhra Pradesh, India 总被引:1,自引:1,他引:0
In a village-based watershed in Andhra Pradesh, India, it is increasingly difficult for users to access and extract groundwater for irrigation: a 'pumping race' is taking place. A move from groundwater development towards groundwater management is required, with a new perspective on options for change. Through a study of borewell technology and groundwater use, and considering new local developments in electricity supply and participatory resource management, the article argues that groundwater is a resource with 'instructions for use'. The technological dimensions of groundwater irrigation urge its study as a socio-technical process in order to design sustainable and equitable groundwater management. 相似文献
336.
337.
Complete extirpation of a species can generate cascading effects throughout an ecosystem, yet are precisely the goal of island eradications of pest species. “Mesopredator release effect”, an asymmetrical special case of intraguild predation, has been hypothesised as a possible indirect effect from eradications, where superpredator removal can generate a mesopredator increase which may increase the impact on their shared prey. Theoretically this suggests that for intraguild predators, the superpredator may protect the shared prey from mesopredation, and removal of superpredators alone is not recommended. We create a model of long-lived age-structured shared prey and explore the non-equilibrium dynamics of this system. The superpredator can impact all prey life-stages (adult survival and reproductive success) whereas the smaller mesopredator can only impact early life-stages (reproductive success). This model is independently tested with data from a closed oceanic island system where eradication of introduced intraguild predators is possible for conservation of threatened birds. Mesopredator release only occurs in strongly top-down moderated (resource-abundant) systems. Even when mesopredator release can occur, the negative impact of more mesopredators is outweighed by the benefit of superpredator removal, allowing recovery of the prey population. Results are robust to 10% variation in model parameters. The consideration of age-structured prey contradicts previous theoretical results for mesopredator release effect and intraguild predation. Superpredator eradication is vital for population recovery of long-lived insular species. Nonetheless island conservation must retain a whole-ecosystem perspective given the complex trophic relationships among multiple species on islands. 相似文献
338.
The determination of reproductive status and the reconstruction of individual reproductive histories are central to many ecological
studies. In cetaceans, it has been assumed that ovarian scars accumulate with age and provide a lifetime record of female
reproductive history. If ovarian scars persist, the number of scars should increase with age after puberty. To test this,
we examined age, reproductive status and ovarian scars from 187 short-beaked common dolphins (Delphinus delphis) from the eastern North Atlantic. The number of Corpus Albicans (CA) present in ovaries did not increase with age after age
at sexual maturity (ASM), suggesting that ovarian scars are not persistent and that their number at any one time would be
a function of rates of ovulation and healing, the latter being defined here as the resorption or disintegration of CA tissue.
Since female mammals stop ovulating when pregnant, inferences about healing rates could be made by using pregnant females.
Pregnant females had ca. 40% fewer scars than non-pregnant females. This suggests that most CAs would heal quickly, with a
half-life of less than 1 year, although larger scars may persist longer. Therefore, counting CAs would have limited potential
for reconstructing individual reproductive lifetime histories in the common dolphin. A reassessment of the use of ovarian
scars to reconstruct individual life reproductive histories in cetaceans is suggested. 相似文献
339.
Honeybees are highly efficient at regulating the biophysical parameters of their hive according to colony needs. Thermoregulation has been the most extensively studied aspect of nest homeostasis. In contrast, little is known about how humidity is regulated in beehives, if at all. Although high humidity is necessary for brood development, regulation of this parameter by honeybee workers has not yet been demonstrated. In the past, humidity was measured too crudely for a regulation mechanism to be identified. We reassess this issue, using miniaturised data loggers that allow humidity measurements in natural situations and at several places in the nest. We present evidence that workers influence humidity in the hive. However, there are constraints on potential regulation mechanisms because humidity optima may vary in different locations of the nest. Humidity could also depend on variable external factors, such as water availability, which further impair the regulation. Moreover, there are trade-offs with the regulation of temperature and respiratory gas exchanges that can disrupt the establishment of optimal humidity levels. As a result, we argue that workers can only adjust humidity within sub-optimal limits. 相似文献
340.