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81.
Summary. Plants attacked by herbivorous insects emit a blend of volatile compounds that serve as important host location cues for parasitoid
wasps. Variability in the released blend may exist on the whole-plant and withinplant level and can affect the foraging efficiency
of parasitoids. We comprehensively assessed the kinetics of herbivore-induced volatiles in soybean in the context of growth
stage, plant organ, leaf age, and direction of signal transport. The observed patterns were used to test the predictions of
the optimal defence hypothesis (OD). We found that plants in the vegetative stage emitted 10-fold more volatiles per biomass
than reproductive plants and young leaves emitted >2.6 times more volatiles than old leaves. Systemic induction in single
leaves was stronger and faster by one day in acropetal than in basipetal direction while no systemic induction was found in
pods. Herbivore-damaged leaves had a 200-fold higher release rate than pods. To some extent these findings support the OD:
i) indirect defence levels were increased in response to herbivory and ii) young leaves, which are more valuable, emitted
more volatiles. However, the fact that reproductive structures emitted no constitutive or very few inducible volatiles is
in seeming contrast to the OD predictions. We argue that in case of volatile emission the OD can only partially explain the
patterns of defence allocation due to the peculiarity that volatiles act as signals not as toxins or repellents. 相似文献
82.
Meaghan A. Vavrek Chris K. Elvidge Robert DeCaire Brenna Belland Christopher D. Jackson Grant E. Brown 《Chemoecology》2008,18(4):255-261
Summary. Several freshwater invertebrate and vertebrate prey species rely on chemosensory cues, including non-injury released disturbance
cues, to assess and avoid local predation threats. The prevailing hypothesis is that a pulse of ammonia released by disturbed
or stressed prey functions as the disturbance cue. Here, we test this hypothesis in two phylogenetically distant freshwater
prey fishes, convict cichlids and rainbow trout. In our first experiment, we measured NH4
+ concentration in tanks containing shoals of cichlid or trout before and after exposure to a realistic model predator (or
left undisturbed). We failed to find an increase in ambient NH4
+ concentration for either cichlids or trout. In our second experiment, we exposed cichlids or trout to NH4
+ at 0.1 or 0.5 mg L−1 (or a distilled water control) and measured the change in antipredator behaviour (time moving, foraging rate and area use).
We found no consistent increase in antipredator behaviour in response to NH4
+. In our third study, we exposed cichlids and trout to the disturbance cues of cichlids or trout (versus the odour of undisturbed
donors). We found significant increases in antipredator behaviour, regardless of donor species, for both cichlids and trout.
Thus, the results of our first two experiments do not support the hypothesis that ammonium functions as a disturbance cue
in prey fishes. However, the results of our final experiment do confirm the use of disturbance cues in convict cichlids and
rainbow trout and support that hypothesis that the disturbance cue is indeed some generalized metabolic byproduct. 相似文献
83.
Summary. To exploit biologically active compounds from white clover (Trifolium repens L.) for suppressing weeds and soil-borne diseases, either as isolated products (biopesticides) or through cultivars with
enhanced production of these compounds, the biologically active compounds must be identified, plant content measured, and
their fate in soil known. The present review summarizes the published knowledge needed for such exploitation; providing essential
information on structure and concentration of flavonols, flavones, condensed tannins, isoflavones, isoflavanones, pterocarpans,
coumestans, cyanogenic glucosides, and saponins in healthy and stressed white clover plants. Various stresses and particular
cultivars affect the concentrations of several of the compounds. Information on biological effects and the degradation/transformation
of these compounds in plants or by microorganisms is available. There is no information on the degradation pathway in soil,
the mechanisms of exudation and leaching of compounds from plants, and soil sorption properties of the compounds. The clover
soil fatigue problem is increasing in grasslands and causes problems especially in organic farming. Research efforts focused
on biological elements of clover soil fatigue have not explained it, and the influence of secondary metabolites has not been
investigated. There are few investigations into the interaction between beneficial fungi/fungal-diseases and the occurrence
of biologically active secondary metabolites in white clover plants. Such studies are critical to better understand beneficial
fungi and pathogens. 相似文献
84.
Golden Eagle fatalities and the continental‐scale consequences of local wind‐energy generation
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Todd E. Katzner David M. Nelson Melissa A. Braham Jacqueline M. Doyle Nadia B. Fernandez Adam E. Duerr Peter H. Bloom Matthew C. Fitzpatrick Tricia A. Miller Renee C. E. Culver Loan Braswell J. Andrew DeWoody 《Conservation biology》2017,31(2):406-415
Renewable energy production is expanding rapidly despite mostly unknown environmental effects on wildlife and habitats. We used genetic and stable isotope data collected from Golden Eagles (Aquila chrysaetos) killed at the Altamont Pass Wind Resource Area (APWRA) in California in demographic models to test hypotheses about the geographic extent and demographic consequences of fatalities caused by renewable energy facilities. Geospatial analyses of δ2H values obtained from feathers showed that ≥25% of these APWRA‐killed eagles were recent immigrants to the population, most from long distances away (>100 km). Data from nuclear genes indicated this subset of immigrant eagles was genetically similar to birds identified as locals from the δ2H data. Demographic models implied that in the face of this mortality, the apparent stability of the local Golden Eagle population was maintained by continental‐scale immigration. These analyses demonstrate that ecosystem management decisions concerning the effects of local‐scale renewable energy can have continental‐scale consequences. 相似文献
85.
Culturomic tools enable the exploration of trends in human–nature interactions, although they entail inherent biases and necessitate careful validation. Furthermore, people may engage with nature across different culturomic data sets differently. We evaluated people's digital interest and engagement with plant species based on Wikipedia and Google data and explored the conservation implications of these temporal interest patterns. As a case study, we explored the digital footprints of the most popular plant species in Israel. We analyzed 4 years of daily page views from Hebrew Wikipedia and 10 years of daily Google search volume in Israel. We modeled popularity of plant species in these 2 data sets based on a suite of plant attributes. We further explored the seasonal trends of people's interest in each species. We found differences in how people interacted digitally with plants in Wikipedia and Google. Overall, in Google, searches for species that have utility to humans were more common, whereas in Wikipedia, plants that serve as cultural emblems received more attention. Furthermore, in Google, popular species attracted more attention over time, opposite to the trend in Wikipedia. In Google, interest in species with short bloom duration exhibited more pronounced seasonal patterns, whereas in Wikipedia, seasonality of interest increased as bloom duration increased. Together, our results suggest that people's digital interactions with nature may be inherently different depending on the sources explored, which may affect use of this information for conservation. Although culturomics holds much promise, better understanding of its underpinnings is important when translating insights into conservation actions. 相似文献
86.
Dynamical models usually assume that predation occurs between mature stages and/or between mature and immature stages. In this work a stage-structured discrete time model is developed for a system where intraguild predation takes place only in the course of immature stages of predator and its prey. Therefore, the proposed mathematical setup demands functional relations linking predation in immature life stages with survival and fecundity in mature stages. The behavior of the model is examined in order to investigate the interplay among predator attack rate, its satiation of prey consumption and the success of intraguild predator invasion. 相似文献
87.
The spatial pattern of the different species in complex ecosystems reflects the underlying ecological processes. In this paper a second order moment function is proposed and tested to analyse the spatial distribution of a mark, which could be a tree characteristic such as diameter or height, between two different types of points, which could be two different tree species. The proposed function was a conditional density function based on the intertype Krs(d) function, incorporating as test function the correlation of the marks between pairs composed of points of different types. The results obtained in simulated and real plots prove that the function is capable of revealing the scale at which spatial correlation of the mark between two types of points exists. The proposed function allows the spatial association between individuals of different species at different life stages to be identified. This analysis may reveal information on species ecology and interspecific interactions in forest ecosystems. 相似文献
88.
89.
Summary. Increased abundance of several aliphatic benzyl
and phenylethyl alkanoates were previously associated with
reduced defoliation of
Eucalyptus globulus Labill. by the
autumn gum moth (Mnesampela privata Guenée) in two
clonally replicated F2 families. We examine the robustness
of this association by comparing the abundance of the
implicated foliar wax compounds with defoliation levels in
three plantation sites and a genetics trial in northern
Tasmania. At all locations, the aliphatic alkanoate, benzyl
n-tetracosanoate (C24), was found in significantly higher
abundance in the foliar wax of E. globulus trees that had displayed low M. privata damage (designated resistant) compared to trees that had displayed high damage (designated
susceptible). Further, when sites were combined, benzyl
n-tetracosanoate (C24) accounted for 16 % of variation in
field defoliation. Field defoliation was also positively correlated
to M. privata oviposition both in the field and on
foliage sprigs in a cage. In the cage bioassay, oviposition
accounted for 20 % of variation in field defoliation
making it a better predictor of tree defoliation in the field
than either field oviposition, which accounted for 9 % of
variation, or screening foliage for the abundance of benzyl
n-tetracosanoate (C24). Despite both benzyl n-tetracosanoate
(C24) and oviposition being related to field defoliation, there
was no statistically significant relationship between the
abundance of benzyl n-tetracosanoate (C24) and oviposition
in the field or cage bioassay. Further work is therefore
required to determine if increased levels of this compound in
the foliar wax operates as a direct deterrent to M. privataoviposition. 相似文献
90.
T. J. Bergman J. C. Beehner D. L. Cheney R. M. Seyfarth P. L. Whitten 《Behavioral ecology and sociobiology》2006,59(4):480-489
To date, research on testosterone and behavior has focused on individuals, even when studying social behaviors that necessarily
involve multiple participants. Here, we explore male responses to other males of different dominance ranks and testosterone
levels in a population of wild baboons. In chacma baboons (Papio hamadryas ursinus) of the Okavango Delta, a male’s testosterone is related to his rank trajectory and, therefore, the threat he poses to other
males. To examine the effects of testosterone and rank on male–male interactions, we used playback experiments to measure
how a target male responded to the simulated approach of another male, scoring responses by whether or not the subject moved
away from the speaker in the first minute. High testosterone subjects did not move away from the speaker more often than low
testosterone subjects, but high testosterone callers elicited a move more often than low testosterone callers. When the combined
testosterone of the subject and caller was high, moves were most common. The rank relationship between subject and caller
did not predict moves, but the effect of combined testosterone on moving was most pronounced in adjacently ranked males. Adjacently
ranked, high testosterone males are the most likely to be competing for each others’ rank, and our experiments on these dyads
elicited the most moves. Both behavioral and experimental observations indicate that testosterone may be more important than
the rank relationship in predicting the outcome of male–male interactions. Furthermore, combined information on the testosterone
of both males was the best predictor of results, highlighting the utility of dyadic analyses when relating testosterone to
behavior. 相似文献