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161.
In numerous spider species, reproductive success of adult females has been shown to be positively correlated with their body mass. We suggest, however, that spiders may incur greater foraging costs as their body mass increases due to the numerous and complex locomotor bouts needed to build an orb-web. Such a body-mass-dependent cost should, in turn, affect the web-building decisions of spiders. In the laboratory, we tested the influence of body mass on energetic expenditure (measured as mass loss) during web-building behavior in Zygiella x-notata. Our results showed (1) that energetic costs associated with web-building were closely related to body mass and to web-building activity, and (2) that as their body mass increased, spiders reduced the amount of silk used per web, while their foraging effort simultaneously increased. This work gives new insights into web-building behavior and energy allocation strategies of weaving spiders. 相似文献
162.
Rima Slim Joelle Soulié Jan Hotmar Bertrand Lecolier Guy Bercau Alain Bernheim 《黑龙江环境通报》1994,14(1):23-28
A case of 45,X/46,X,+mar mosaicism was detected in a male fetus (27 weeks' gestation) referred for karyotype analysis following the observation of a short femur at the ultrasound scan. Analysis of 12 Y-chromosome loci by fluorescent in situ hybridization (FISH) and polymerase chain reaction (PCR) demonstrated that the marker chromosome is of Y origin and corresponds to an authentic isochromosome for the short arm of the Y chromosome, i(Yp). The breakpoint on this marker is in YQ11·1 close to the centromere. The present report illustrates the importance of FISH and PCR techniques as a complement to cytogenetic methods for accurate identification and characterization of chromosome rearrangements in prenatal diagnosis. 相似文献
163.
Christine Errard Francisca Ruano Freddie-Jeanne Richard Alain Lenoir Alberto Tinaut Abraham Hefetz 《Chemoecology》2006,16(4):235-240
Summary. Proformica longiseta exists as two populations in the Sierra Nevada Mountains in Spain, only one of which is parasitized by the slave-maker ant
Rossomyrmex minuchae. To investigate the possible effect of co-evolutionary pressures on cuticular hydrocarbon (CHC) profiles (the presumed nestmate
recognition cues), we performed a comparative analysis of the CHC of R. minuchae and P. longiseta colonies from both the allopatric and sympatric populations; the latter includes samples of enslaved as well as free-living
workers. Discriminant analyses based on these chemical profiles showed two clear profile groups: the first comprised R. minuchae and both enslaved and free-living P. longiseta from the sympatric population; and the second the allopatric P. longiseta workers. As expected, the profiles of the two sympatric P. longiseta groups (enslaved and free-living) were distinct; but, interestingly, those of the enslaved P. longiseta and its parasite R. minuchae were also distinguishable. This indicates that despite their cohabitation each species maintains its own chemical identity.
Profile similarity between the sympatric free-living P. longiseta and its parasite may explain the lower than expected aggression observed during raids. We further speculate that in view
of the differences between the sympatric and allopatric population of P. longiseta, co-evolutionary pressures have driven changes in the profile of the former to better match that of its parasite R. minuchae. Such an adjustment may have enabled nests of the sympatric P. longiseta to endure multiple raids by the parasite (due to the reduced aggression) and thus to continue to reproduce despite the damage
inflicted by the raids. 相似文献
164.
Sylvie Gauthier Alain Leduc Yves Bergeron 《Environmental monitoring and assessment》1996,39(1-3):417-434
In natural boreal forests, disturbances such as fire and variation in surficial deposits create a mosaic of forest stands with different species composition and age. At the landscape level, this variety of stands can be considered as the natural mosaic diversity. In this paper, we describe a model that can be used to estimate the natural diversity level of landscapes. We sampled 624 stands for tree species composition and surficial deposits in eight stand-age classes corresponding to eight fire episodes in the region of Lake Duparquet, Abitibi, Québec at the southern fringe of the Boreal Forest. For six surficial deposit types, stand composition data were used to define equations for vegetation changes with time for a chronosequence of 230 years for four forest types. Using Van Wagner's (1978) model of age class distribution of stands, the proportion of each forest type for several lengths of fire cycle were defined. Finally, for real landscapes (ecological districts) of the ecological region of the Basses-Terres d'Amos, the proportion of forest types were weighted by the proportion of each surficial deposit type using ecological map information. Examples of the possible uses of the model for management purposes, such as biodiversity conservation and comparisons of different landscapes in terms of diversity and sensitivity to fire regime changes, are discussed. 相似文献
165.
The use of the Bel W3 tobacco variety revealed the existence of an intrapopulation variation of sensitivity to the ozone effect leading to the isolation of two categories of plants: sensitive and resistant. The use of sensitive plants revealed the existence of a biological ozone efficiency threshold at a level close to 34.5 ppb. Under the threshold, the biological effects observed were weak or very weak. They can be attributed to the occurrence of secondary phenomena (chemical, physiological, pathological, etc.), inducing or inhibiting necrosis, which become perceptible here. 相似文献
166.
Degradation of diuron by the electro-Fenton process 总被引:2,自引:0,他引:2
Mohamed?C.?Edelahi Nihal?Oturan Mehmet?A.?OturanEmail author Yann?Padellec Alain?Bermond Kacem?El Kacemi 《Environmental Chemistry Letters》2003,1(4):233-236
The degradation of the herbicide diuron has been undertaken by electrochemical advanced oxidation in aqueous solution. This process generates catalytically hydroxyl radicals that are strong oxidizing reagents for the oxidation of organic substances. Hydroxyl radicals degrade diuron in less than 10 min. Kinetic results evidence a pseudo-first-order degradation, with a rate constant of reaction between diuron and hydroxyl radicals of 4.8x109 M–1 s–1. Several degradation products were identified by chromatography-mass spectrometry (LC-MS). The mineralization degree of a 1.7x10–4 M diuron solution reached 93% at 1,000 coulombs. 相似文献
167.
Raphaël Boulay Abraham Hefetz Xim Cerdá Séverine Devers Wittko Francke Robert Twele Alain Lenoir 《Behavioral ecology and sociobiology》2007,61(10):1531-1541
Models based on the kin selection theory predict that in social hymenopterans, queens may favor a lower investment in the
production of sexuals than workers. However, in perennial colonies, this conflict may be tuned down by colony-level selection
because of the trade off between colony survival and reproductive allocation. In this study, we present a survey of sexual
production in colonies of Aphaenogaster senilis, a common species of ant in the Iberian Peninsula. Similar to most species that reproduce by fission, males were found in
large excess compared to gynes (172:1). Sexuals were more likely to be found in queenless than in queenright (QR) field colonies.
However, we also found a few gynes and numerous males in very large QR colonies. We compared these data with those available
in the literature for A. rudis, a congeneric species from North America that has independent colony founding. The sex ratio in this species was only five
males for each female, and sexuals were mostly found in QR nests, irrespective of colony size. We confirmed queen inhibition
of sexual production in A. senilis in laboratory experiments and provide evidence that this inhibition is mediated by a nonvolatile pheromone. To seek the potential
source of such a queen pheromone, we analyzed the secretions of two conspicuous exocrine glands, the Dufour’s and postpharyngeal
glands (DG and PPG, respectively) in both queens and workers. Both secretions were composed of hydrocarbons, but that of DG
also contained small quantities of tetradecanal and hexadecanal. The hydrocarbon profile of the DG and PPG showed notable
caste specificity suggesting a role in caste-related behavior. The PPG secretions also differed between colonies suggesting
its role in colony-level recognition. We suggest that in A. senilis, there are two modes of colony fission: First, in very large colonies, gynes are produced, probably because of the dilution
of the queen pheromone, and consequently one or more gynes leave the mother colony with workers and brood to found a new nest.
This is beneficial at the colony level because it avoids the production of costly sexuals in small colonies. However, because
the queen and workers have different optima for sexual production, we hypothesize that queens tend to overproduce the pheromone
to delay their production. This in turn may drive workers to leave the mother colony during nest relocation and to produce
sexuals once they are away from the queen’s influence, creating a second mode of colony fission. 相似文献
168.
Measuring the welfare cost of climate change policies is a real challenge, raising difficult issues of micro- and macro-economics: cost-benefit analysis on the one hand, foreign trade and international specialization on the second hand. At the domestic level the possible existence of distortions, in particular in the fiscal system, may either increase or alleviate the welfare cost of a climate change policy, as illustrated by the debate on double dividend. Effects on the prices in international markets and distorted competition between countries committed to abate (Annex B) and uncommitted countries affect both the sharing of the burden, in particular through the change in the terms of trade, and the allocation of activities with the frequently waved threat of delocalization. Based on a companion theoretical analysis, the present paper aims at putting order in the welfare analysis of climate change policy and to present and compare various estimations, issuing from macro- or computable general equilibrium models. Beside the global welfare cost, the paper focuses on the marginal abatement cost and its relation to the carbon price.Most present conceptual and applied analysis is based on the case of a single domestic household-consumer. Taking into account several consumers raises new challenges, concerning equity but even more fundamentally the mere definition of fiscal distortion, which have not yet been really addressed. 相似文献
169.
Jan Šobotník David Sillam-Dussès František Weyda Alain Dejean Yves Roisin Robert Hanus Thomas Bourguignon 《Die Naturwissenschaften》2010,97(5):495-503
The presence of the frontal gland is well established in termite soldiers of Rhinotermitidae, Serritermitidae, and Termitidae. It is one of their main defensive adaptations or even an exclusive weapon. The gland was also occasionally reported in alate imagoes, but never in the worker caste. Here, we report the first observation of a frontal gland in workers of several Neotropical and one African species of Apicotermitinae. The ultrastructure of Aparatermes cingulatus and Anoplotermes nr. subterraneus is described in detail. In these two species, the gland is well-developed, functional and consists of class 1 secretory cells. The presence of envelope cells, wrapping the gland, is an unusual feature, as well as the presence of several zonulae adherens, connecting neighbouring glandular cells. The frontal gland of workers is homologous to this organ in soldiers and imagoes, as evidenced by the same position in the head and its connection to the same muscle. However, the defensive role of the frontal gland in workers remains to be confirmed. 相似文献
170.
In studying the ant genus Azteca, a Neotropical group of arboreal species, we aimed to determine the extent to which the ants use predation and/or aggressiveness to protect their host plants from defoliating insects. We compared a territorially dominant, carton-nester, Azteca chartifex, and three plant-ant species. Azteca alfari and Azteca ovaticeps are associated with the myrmecophyte Cecropia (Cecropiaceae) and their colonies shelter in its hollow branches; whereas Azteca bequaerti is associated with Tococa guianensis (Melastomataceae) and its colonies shelter in leaf pouches situated at the base of the laminas. Whereas A. bequaerti workers react to the vibrations transmitted by the lamina when an alien insect lands on a leaf making it unnecessary for them to patrol their plant, the workers of the three other species rather discover prey by contact. The workers of all four species use a predatory behaviour involving spread-eagling alien insects after recruiting nestmates at short range, and, in some cases, at long range. Because A. alfari and A. ovaticeps discard part of the insects they kill, we deduced that the workers' predatory behaviour and territorial aggressiveness combine in the biotic defence of their host tree. 相似文献