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721.
Three marine diatoms Lauderia annulata Cleve, Odontella sinensis (Greville) Grunow and Thalassiosira rotula Meunier were exposed to ultraviolet (UV) radiation of different wavebands under controlled laboratory conditions (0.035 vol%
CO2, 18 °C). Several changes in the patterns of pigments in these organisms were seen depending on the waveband of UV radiation
and species examined. UV-B and UV-B plus UV-A radiation led to a reduction in the overall pigment content of all three diatoms.
The uptake of 15N-ammonium was less affected by 5-h UV-A (WG 320) but significantly reduced after UV-B and UV-B plus UV-A exposure. The pattern
of free amino acid pools varied depending on the applied UV wavebands and the tested diatom. The main protein-bound amino
acids of T. rotula decreased after 5-h UV irradiance except leucine. Contents of adenosine 5′-mono-, di-, and triphosphate (AMP, ADP and ATP)
were affected differently by UV radiation; ATP values increased at the end of UV-B and UV-B plus UV-A exposure. These results
have been discussed with reference to the impact of the different UV sources and the influence on the nitrogen metabolism
in connection to pigments and supply with energy.
Received: 13 May 1997 / Accepted: 11 October 1997 相似文献
722.
Starch-gel electrophoresis of allozymes was used to differentiate the two red mullet species (Mullus barbatus L. and M. surmuletus L.) in the Mediterranean Sea and, further, to investigate the genetic stock structure of M. barbatus in the eastern Mediterranean area. Twenty putative enzyme-coding loci were examined in eight M. barbatus samples caught in the Aegean and Ionian Seas (Greece) and in the Gulf of Lion (France), and two M. surmuletus samples caught in the Aegean and Gulf of Lion. A high degree of genetic polymorphism was found in both species. Species-specific
electrophoretic patterns were found in PGI* and PGM*. Estimates of variance of allele frequencies among samples (F
ST) and 2 analyses both revealed significant differences (P < 0.05) among the M. barbatus samples. Most of the genetic variation was among samples regardless of region. The mean value of Nei's genetic distance between
the two species was 0.329. Genetic distance among M. barbatus samples was low (maximum Nei's D = 0.012), with the sample from Platania differing most from other M. barbatus samples. This is probably be due to founder effects existing at this area. These results suggest that allozyme analysis may
provide important information on the genetic structure of the red mullet to ensure sustainable management of this species.
Received: 7 May 1997 / Accepted: 13 October 1997 相似文献
723.
James V. Briskie Robert Montgomerie Tarmo Põldmaa Peter T. Boag 《Behavioral ecology and sociobiology》1998,43(3):181-190
In species where females copulate with more than one male during a single breeding attempt, males risk investing in offspring
that are not their own. In the polygynandrous Smith's longspur (Calcarius pictus), females copulate sequentially with one to three males for each clutch of eggs and most of these males later assist in feeding
the young. Using multilocus DNA profiling, we determined that there was mixed paternity in >75% of broods (n=31) but that few offspring (<1% of 114 nestlings) were sired by males outside the polygynandrous group. Male feeding rate
increased significantly with the number of young sired, with males siring four nestlings feeding the brood at double the frequency
of males siring only a single nestling. However, male Smith's longspurs appear to show a graded adjustment of paternal care
in response to paternity only when other males are available to compensate for reduced care: feeding rate did not vary in
relation to paternity when only one male provisioned young at the nest. There was no evidence that males could recognise their
own offspring within a brood and feed them preferentially. The number of offspring sired by each male was significantly correlated
with the number of days spent copulating with the attending female: on average, a male sired one offspring for every 2 days
of copulatory access. If males use their access to females to estimate paternity (and thereby decide on their subsequent level
of parental investment), a positive relationship is expected between the amount of female access and the subsequent feeding
rate to the nestlings. Nonetheless, male feeding effort was only weakly correlated with female access and more study is needed
to determine how males estimate their paternity in a brood.
Received: 1 June 1997 / Accepted after revision: 1 April 1998 相似文献
724.
The area around Chandidongri (latitude 21 deg 02 prime N and longitude 80 deg 37 prime E) is covered by granitic gneisses and amphibolites of the Amgaon Group and granites and rhyolites of the Dongargarh super group. The granites which cover the major portion of the area have been intruded into by a number of dolerite and epidiorite dykes and traversed by a few N–S trending shear zones. A well-known fluorite deposit is located along the Lamtidongri–Kotnapani shear zone. Besides this deposit, the authors have located a few occurrences of fluorite along other shear zones where epidiorite dykes are in association with granites. A number of cases of fluorosis have been reported from those parts of Rajasthan and Andhra Pradesh which are covered by granitic rocks and also from the eastern parts of Bhandara district which are adjacent to the area described here. The Chandidongri area is mainly covered by granitic rocks, which at places show the presence of fluorite mineralisation. Taking into consideration these facts, the authors have investigated the area to study the cases of fluorosis if any, and the impact of geology and fluorite mining on the water quality in this region. During the survey, we have not come across any cases of fluorosis in this region. The pH is more than 7 and the fluoride concentration is within the permissible limit. 相似文献
725.
Coalitionary mate guarding by male chimpanzees at Ngogo, Kibale National Park, Uganda 总被引:13,自引:0,他引:13
David P. Watts 《Behavioral ecology and sociobiology》1998,44(1):43-55
Cooperative mate guarding by males is unusual in mammals and birds, largely because fertilizations are non-shareable. Chimpanzees
live in fission-fusion communities that have cores of philopatric males who cooperate in inter-group aggression and in defending
access to the females in their community. Male contest mating competition is restrained within communities, but single high-ranking
males sometimes try to mate guard estrous females. Data from an unusually large chimpanzee commmunity at Ngogo, Kibale National
Park, Uganda, that contains more males than any previously studied community show new variation in chimpanzee mate-guarding
behavior. Contrary to expectation given the large number of males, mate guarding was as common as, or more common than, at
other sites, and males other than the alpha male guarded more often. More strikingly, pairs or trios of top-ranking males
sometimes engaged in cooperative aggression to prevent estrous females from mating with other males, but tolerated each other's
mating activities. Both single males and coalitions mostly guarded periovulatory females. Mate-guarding coalitions were previously
unknown in chimpanzees. Coalitions occurred in large mating parties, seemingly because these often contained too many males
for single males to maintain exclusive access to estrous females. Coalition members gained higher shares of copulations than
they could have expected from solo mate guarding, and suffered lower per capita costs of guarding (as inferred from aggression
rates). Two males who most often participated in coalitions formed two-male coalitions at about the point where the number
of males present made it unlikely that either could get 50% or more of total copulations on his own, and formed trios when
this value dropped below 33%. Kin selection could be a factor in cooperation among male chimpanzees, but coalition members
were not necessarily close relatives and the apparent structure of payoffs fit that of mutualism. Furthermore, reliance of
male chimpanzees on support from allies to maintain high rank could have led to trading of mating exclusivity for support
against mating competitors.
Received: 28 May 1997 / Accepted after revision: 16 May 1998 相似文献
726.
Forestry Trees as Invasive Aliens 总被引:14,自引:0,他引:14
David M. Richardson 《Conservation biology》1998,12(1):18-26
727.
Angulo J.M González-Manteiga W. Febrero-Bande M. Alonso F. J. 《Environmental and Ecological Statistics》1998,5(4):297-316
The problem of estimation and prediction of a spatial-temporal stochastic process, observed at regular times and irregularly in space, is considered. A mixed formulation involving a non- parametric component, accounting for a deterministic trend and the effect of exogenous variables, and a parametric component representing the purely spatio-temporal random variation is proposed. Correspondingly, a two-step procedure, first addressing the estimation of the non- parametric component, and then the estimation of the parametric component is developed from the residual series obtained, with spatial-temporal prediction being performed in terms of suitable spatial interpolation of the temporal variation structure. The proposed model formula-tion, together with the estimation and prediction procedure, are applied using a Gaussian ARMA structure for temporal modelling to space-time forecasting from real data of air pollution concentration levels in the region surrounding a power station in northwest Spain. 相似文献
728.
729.
730.
M. Gochfeld D. J. Gochfeld D. Minton B. G. Murray Jr P. Pyle N. Seto D. Smith J. Burger 《Environmental monitoring and assessment》1999,59(3):343-358
Levels of environmental pollutants are usually higher in mainland and coastal areas than in offshore or oceanic islands due to higher inputs from agricultural and industrial sources. Levels of heavy metals are usually higher in adult than in young birds, because they have had longer to accumulate metals in their tissues, and/or because they may eat larger, more contaminated, prey. We examined the levels of arsenic, cadmium, chromium, lead, manganese, mercury, and selenium in the adults and young of Bonin petrel (Pterodroma hypoleuca), Christmas shearwater (Puffinus nativitatis) and red-tailed tropicbird (Phaethon rubricauda) on Midway Atoll, and adult wedge-tailed shearwater (Puffinus pacificus) on Midway Atoll and on Manana Island (off Oahu) in the northern Pacific. All birds were analyzed individually except for Christmas Shearwater chicks where samples were pooled to obtain sufficient quantities for analysis. Significant (p<0.05) age-related differences were found for mercury, selenium, manganese and chromium in Bonin petrels, for selenium and mercury in Christmas shearwaters, and for chromium and mercury in Red-tailed Tropicbirds. Lead approached significance for all three species. Adults had higher levels than young except for chromium and manganese in the petrels and arsenic in all three species. There were significant interspecific differences in concentrations of all metals except arsenic for the adults nesting on Midway. Christmas shearwaters had the highest levels of all metals except mercury and chromium. Bonin petrels, the smallest species examined, had mercury levels that were over three times higher than any of the adults of the other three species. For wedge-tailed shearwaters, levels of chromium and lead were significantly higher, and manganese and selenium were lower on Midway than Manana. Knowledge of the foraging ranges and habits of these far-ranging seabirds is inadequately known, but does not currently explain the observed differences among species. We could not find a consistent pattern of differences between the burrow nesting species (Bonin petrel, Wedge-tailed shearwater) and the surface nesting tropicbirds. There was no consistent pairwise correlation between any metals across all species. 相似文献