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971.
Thomas Kneib Felix Knauer Helmut Küchenhoff 《Environmental and Ecological Statistics》2011,18(1):1-25
The investigation of animal habitat selection aims at the detection of selective usage of habitat types and the identification
of covariates influencing their selection. The results not only allow for a better understanding of the habitat selection
process but are also intended to help improve the conservation of animals. Usually, habitat selection by larger animals is
assessed by radio-tracking or visual observation studies, where the chosen habitat is determined for some animals at a set
of specific points in time. Hence the resulting data often have the following structure: a categorical variable indicating
the habitat type selected by an animal at a specific point in time is repeatedly observed and will be explained by covariates.
These may either describe properties of the habitat types currently available and/or properties of the animal. In this paper,
we present a general approach to the analysis of such data in a categorical regression setup. The proposed model generalizes
and improves upon several of the approaches previously discussed in the literature. In particular, it accounts for changing
habitat availability due to the movement of animals within the observation area. It incorporates both habitat- and animal-specific
covariates, and includes individual-specific random effects to account for correlations introduced by the repeated measurements
on single animals. Furthermore, the assumption that the effects are linear can be dropped by including the effects in nonparametric
manner based on a penalized spline approach. The methodology is implemented in a freely available software package. We demonstrate
the general applicability and the potential of the proposed approach in two case studies: The analysis of a songbird community
in South-America and a study on brown bears in Central Europe. 相似文献
972.
Orb web spiders of the genus Argiope are permanently located at the hub of the orb web and are thus vulnerable to changing environmental conditions. Severe damage
to the web by non-prey animals can have a significant impact on survival, through the cost of producing expensive silk and
the loss of foraging opportunities. Thus, selection should favor web protection mechanisms, and the conspicuous web decorations,
typical of Argiope spiders, may play a role. Decorated webs suffer less damage than undecorated webs, consistent with the view that they advertise
the presence of the web to non-prey animals that may damage the web. However, whether spiders respond to web damage by increasing
investment in web decorations has not been investigated. We subjected adult St. Andrew's Cross spider (Argiope keyserlingi) females to three levels of web damage and recorded their subsequent web-decorating behavior. Mild damage, similar to that
caused by impacting prey, did not affect either web building or decorating behavior. However, spiders subjected to substantial
web damage both reduced the size of subsequent webs and increased investment in web decoration size. These data are consistent
with an advertising role of web decorations. 相似文献
973.
Simon W. Townsend Markus Zöttl Marta B. Manser 《Behavioral ecology and sociobiology》2011,65(10):1927-1934
Socio-demographic factors, such as group size and their effect on predation vulnerability, have, in addition to intrinsic
factors, dominated as explanations when attempting to understand animal vigilance behaviour. It is generally assumed that
animals evaluate these external factors visually; however, many socially foraging species adopt a foraging technique that
directly compromises the visual system. In these instances, such species may instead rely more on the acoustical medium to
assess their relative risk and guide their subsequent anti-predator behaviour. We addressed this question in the socially
foraging meerkat (Suricata suricatta). Meerkats forage with their head down, but at the same time frequently produce close calls (‘Foraging’ close calls). Close
calls are also produced just after an individual has briefly scanned the surrounding environment for predators (‘Guarding’
close calls). Here, we firstly show that these Guarding and Foraging close call variants are in fact acoustically distinct
and secondly subjects are less vigilant (in terms of frequency and time) when exposed to Guarding close call playbacks than
when they hear Foraging close calls. We argue that this is the first evidence for socially foraging animals using the information
encoded within calls, the main adaptive function of which is unrelated to immediate predator encounters, to coordinate their
vigilance behaviour. In addition, these results provide new insights into the potential cognitive mechanisms underlying anti-predator
behaviour and suggest meerkats may be capable of signalling to group members the ‘absence’ of predatory threat. If we are
to fully understand the complexities underlying the coordination of animal anti-predator behaviour, we encourage future studies
to take these additional auditory and cognitive dimensions into account. 相似文献
974.
Huei-Jen Tseng Ren-Chung Cheng Sheng-Hai Wu Sean J. Blamires I-Min Tso 《Behavioral ecology and sociobiology》2011,65(12):2351-2359
Animals may build multiple structures to provide benefits to counter the costs of building. Many orb web spiders add multiple
structures, e.g., barricading barrier webs and silk decorations, to their webs and these structures have been hypothesized
to function to deter predators or attract prey. The heavily armored spiny spiders construct barrier webs around their orb
webs and decorate them with conspicuous silk tufts. Why these organisms, already well protected by a thick cuticle and spines,
make the extra investment of building barrier webs and adding conspicuous silk decorations is not known. We predicted that
these structures function to both attract prey and deter predators. Field experiments were conducted in two consecutive years
using orb webs built by the East Asian spiny spider Thelacantha brevispina. We either (1) concealed the decoration, (2) removed the barrier webs, or (3) left the decorations and barrier webs intact.
We found year and treatment to interactively influence prey interception rates. In 2010, but not in 2009, we found prey interception
with T. brevispina webs to be greater when the decorations were conspicuous than when they were concealed suggesting that the decorations may
lure prey. Prey interception was lower when the barrier webs were present without decorations compared to when they were absent
without decorations. The prey-attracting function of the decorations thus may counter the reduction in prey interception incurred
by adding a barrier web. Predatory wasp interactions were not influenced by any of our treatments, probably because the spiders’
thick cuticle is the primary means of protection from wasps. Bird predation events, while rare, occurred only when decorations
were concealed or the barrier webs were removed. It is therefore plausible that the tuft decorations both lure prey and deter
birds. 相似文献
975.
Jonathan N. Pruitt Susan E. Riechert David J. Harris 《Behavioral ecology and sociobiology》2011,65(10):1957-1966
Relatively few investigations explicitly test for concordant versus conflicting selection pressures from intrasexual versus
intersexual selection. Here, we examine the effects of male body mass and behavioral type (BT) on reproductive success in
the spider Anelosimus studiosus, with emphasis placed on the potential interaction between intrasexual and intersexual selection influences. Female A. studiosus exhibit either an aggressive-active or docile-passive BT, both of which co-occur in multifemale colonies. Males, in contrast, exhibit a more continuous distribution of
behavioral tendencies. We investigated the male traits favored by females in five trial types: one docile female, one aggressive
female, four docile females, four aggressive females, and two docile and two aggressive females. Male reproductive success
was estimated by the number eggs produced by females following staged mating trials. In previous work, it was established
that large aggressive males are favored in male–male contests, an intrasexual effect. However, large aggressive males were
not universally favored here. We failed to detect an effect of male body mass or aggressiveness on reproductive success in
trials with all docile females; however, in situations involving aggressive females, large aggressive males experienced diminished
reproductive success relative to small docile males. Large, aggressive males were also more likely to be attacked and killed
by aggressive females in the first 20 min of staged encounters and were more likely to be found dead after 72 h of unobserved
interactions. Taken together, our data suggest that the reproductive consequences of male traits differ based on (1) the aspect
of sexual selection being considered (intrasexual versus intersexual) and (2) the BT of their prospective mates: large aggressive
males enjoy advantages in intrasexual selection and when courting docile females and small docile males experience reduced
risk of cannibalism and increased reproductive success with aggressive females. 相似文献
976.
Shane A. Richards Mark J. Whittingham Philip A. Stephens 《Behavioral ecology and sociobiology》2011,65(1):77-89
Behavioural ecologists often study complex systems in which multiple hypotheses could be proposed to explain observed phenomena.
For some systems, simple controlled experiments can be employed to reveal part of the complexity; often, however, observational
studies that incorporate a multitude of causal factors may be the only (or preferred) avenue of study. We assess the value
of recently advocated approaches to inference in both contexts. Specifically, we examine the use of information theoretic
(IT) model selection using Akaike’s information criterion (AIC). We find that, for simple analyses, the advantages of switching
to an IT-AIC approach are likely to be slight, especially given recent emphasis on biological rather than statistical significance.
By contrast, the model selection approach embodied by IT approaches offers significant advantages when applied to problems
of more complex causality. Model averaging is an intuitively appealing extension to model selection. However, we were unable
to demonstrate consistent improvements in prediction accuracy when using model averaging with IT-AIC; our equivocal results
suggest that more research is needed on its utility. We illustrate our arguments with worked examples from behavioural experiments. 相似文献
977.
Colby J. Tanner Gül Deniz Salalι Andrew L. Jackson 《Behavioral ecology and sociobiology》2011,65(2):249-256
Human activity can have a large impact on surrounding ecosystems. For example, humans alter resource distributions for other
species, potentially modifying these species competitive dynamics. These changes in local competitive processes are frequently
associated with species invasions. Here, we investigate how differences in resource distribution affect competitive behaviour
using the highly invasive European shore crab (Carcinus maenas). Using a controlled laboratory experiment in combination with behaviour assays and social network analysis, we show that
individuals feeding in habitats with clumped food distributions are more aggressive than individuals feeding in habitats where
food is evenly dispersed, and this aggression is present even on days where crabs are not feeding. Additionally, this persistent
aggression can be induced, suggesting that individuals of this invasive species possess the flexibility to modify their competitive
behaviours in response to differences in food distributions. Furthermore, we show how these individual responses can lead
to changes in overall organisation of aggressive interactions within a population. We discuss these results in relation to
how human impacts can have long-term effects on competitive behavioural strategies, and how behavioural flexibility can allow
invasive species to colonise and persist in highly impacted sites such as urban ecosystems. 相似文献
978.
Nikolai W. F. Bode A. Jamie Wood Daniel W. Franks 《Behavioral ecology and sociobiology》2011,65(2):117-130
The theory of collective motion and the study of animal social networks have, each individually, received much attention.
Currently, most models of collective motion do not consider social network structure. The implications for considering collective
motion and social networks together are likely to be important. Social networks could determine how populations move in, split
up into and form separate groups (social networks affecting collective motion). Conversely, collective movement could change
the structure of social networks by creating social ties that did not exist previously and maintaining existing ties (collective
motion affecting social networks). Thus, there is a need to combine the two areas of research and examine the relationship
between network structure and collective motion. Here, we review different modelling approaches that combine social network
structures and collective motion. Although many of these models have not been developed with ecology in mind, they present
a current context in which a biologically relevant theory can be developed. We argue that future models in ecology should
take inspiration from empirical observations and consider different mechanisms of how social preferences could be expressed
in collectively moving animal groups. 相似文献
979.
Male fitness is often determined by the ability of the male to gain access to multiple mates, although in species that exhibit
sexual cannibalism, males might increase their likelihood of being cannibalized with each encounter. This risk should create
selection for males who are able to perceive potential risks associated with mating encounters. We studied male Schizocosa ocreata wolf spiders to determine whether they use female chemotactile cues (silk, excreta) as indicators of potential risks and
how these cues affected subsequent male courtship behaviors. Female treatments included satiated females vs. starved females,
as well as a treatment where females had recently cannibalized a male S. ocreata. We performed experiments to assess (1) if males use female chemotactile cues to determine potential risks associated with
differing female feeding treatments and alter courtship investment, and 2) how male experience with female chemotactile cues
affected courtship investment in subsequent female encounters. At first encounter, males do not vary courtship investment
(number of bouts, duration, and vigor) with different female feeding treatments. However, male behaviors during subsequent
encounters with female chemotactile cues varied in complex ways, depending on female feeding treatment and male first encounter
experience. These data suggest that male experience impacts perception of female chemical cues and offers the male opportunity
to avoid sexual cannibalism in high-risk situations. 相似文献
980.
David L. Clark J. Andrew Roberts Meghan Rector George W. Uetz 《Behavioral ecology and sociobiology》2011,65(6):1237-1247
Animal color patterns often reflect a compromise between natural selection for crypsis or inconspicuousness to predators and
sexual selection for conspicuousness to potential mates. In leaf litter-dwelling wolf spider species like Schizocosa ocreata, body coloration often closely matches the background coloration of a generally brown environment. However, body parts used
in communication should exhibit high contrast against background coloration. We used spectral analysis to examine male and
female S. ocreata for matching and contrasting coloration against leaf litter. Values were plotted in multivariate color space, based on reflectivity
in different frequency ranges. When viewed from above, colors of both males and females overlap with values for dead brown
leaf litter and soil, suggesting cryptic coloration when viewed by potential predators. However, when viewed from a lateral
perspective, both males and females show color values that are polar opposites of litter backgrounds, suggesting higher contrast
when viewed by other spiders. Moreover, male secondary characters used in visual signaling by S. ocreata (tibia brushes) show the highest level of background contrast. These findings suggest that S. ocreata wolf spiders have color patterns that provide both crypsis and background contrast at the same time, depending on receiver
viewing perspective. 相似文献