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731.
The structure of megabenthic decapod crustacean assemblages on the Galician (north-west Spain) continental shelf (100 to
200 depth) and upper slope (200 to 500 m) was analyzed based on surveys carried out in autumn and spring, from 1980 to 1987.
Forty species belonging to 19 families were caught. The portunid crab Polybius henslowii, a species with pelagic phases, was the most abundant species, but displayed strong spatial and temporal fluctuations. Other
dominant species were the Norway lobster Nephrops norvegicus, the portunid Liocarcinus depurator, the galatheids Munida intermedia and M. sarsi, and the shrimps Solenocera membranacea, Plesionika heterocarpus, Pasiphaea sivado and Dichelopandalus bonnieri. Total abundance and biomass (average values excluding Polybius henslowii = 255 individuals and 2.06 kg/30 min tow) and species richness and diversity, H′ (6.85 species and H′ = 1.45 per tow) displayed a significant positive correlation with depth, and strong interannual fluctuations. The factors
determining community organization were depth and, to a lesser extent, spatial structure. There was clear evidence of bathymetric
zonation, differentiating between species characteristic of the slope (D. bonnieri and Pasiphaea sivado), shelf-slope edge (Macropipus tuberculatus, Pontophilus spinosus, Munida sarsi, S. membranacea, Processa spp.) and shelf (L. depurator, Macropodia tenuirostris, Paguridae and Chlorotocus crassicornis). The spatial zonation was related to changes in oceanography and sediment along the continental margin. Goneplax rhomboides, N. norvegicus, C. crassicornis and Alpheus glaber are benthic species which generally exhibit burrowing behaviour, and they were found mainly in the southern area where there
are fine sediments due to the outwelling from the Rías Baixas. Different benthopelagic shrimps (Pontophilus spinosus, Plesionika heterocarpus,Processa spp. and Pasiphaea sivado) were typical of the zone just north of Fisterra, characterized by a convergence of water masses bringing about an increase
in productivity due to upwelling. The benthic anomuran and brachyuran crabs Munida intermedia, M.␣sarsi, L.␣depurator and Macropipus tuberculatus were characteristic of the northwestern zone between Fisterra and Estaca, where the infauna reaches high biomass despite
coarser sediments with a lower concentration of organic material than in the southern area. Lastly, both the Paguridae and
Macropodia tenuirostris were species typically found in the waters in the northern shelf. Based on interannual changes in assemblage structure, two
periods could be distinguished: between 1980 and 1984, when Polybius henslowii, D. bonnieri and Pasiphaea sivado had abundance peaks; and another period from 1985 to 1987 when L. depurator, Munida intermedia, M.␣sarsi and Macropipus tuberculatus increased in abundance.
Received: 21 May 1996 / Accepted: 9 August 1996 相似文献
732.
Metallothionein-like proteins (MTLs) have been measured by differential pulse polarography every two months during a period
of two and half years in the marine bivalve Macoma balthica from two locations of the Western Scheldt Estuary. The MTL concentrations (0.85 to 7.81 mg g−1 dry wt) are comparable to most values found for other marine invertebrates. These concentrations vary significantly with
the seasons (higher in winter, lower in summer), which is mainly due to body weight fluctuations. Strong correlations exist
between MTL and metal levels. Upon short-term exposure to a mixture of Cd, Cu and Zn, there are on average significant MTL
increases, but important seasonal variations have been observed: in winter, the clams are more sensitive to metals, uptake
more Cd and Cu and induce more MTL than during the warmer months.
Received: 16 May 1997 / Accepted: 6 June 1997 相似文献
733.
B. A. Kerrigan 《Marine Biology》1997,127(3):395-402
The effects of food availability, female size, and social interactions on the quality of Pomacentrus amboinensis larvae at hatching were examined using two field-based experiments. In Experiment 1, food availability and female size significantly
influenced size, eye diameter and levels of yolk reserves of larvae at hatching. Small females (47 to 52 mm standard length,
SL) whose diets were not supplemented, produced the longest larvae (3.0 ± 0.01 mm total length, TL) with the least yolk reserves
(50.1 ± 1.04 μm2). Irrespective of female size, those that received additional food produced larvae with the largest yolk-sacs (large females:
87.60 ± 1.53 μm2; small females: 80.14 ± 1.24 μm2). In Experiment 2, interactions with conspecifics had a greater affect on the somatic development of larvae at hatching than
food availability. Increased social interactions resulted in larvae that were ⋍3% longer, with 2% greater head depth, than
larvae from females that spawned in isolation on the experimental reefs. Fed females produced larvae with ⋍20% more yolk than
larvae from females whose diets were not supplemented. All three factors (food availability, female size, and intensity of
social interactions) tested within these experiments vary spatially and temporally among reefs. There is the potential, therefore,
for larvae at the onset of the planktonic stage to vary in quality, level of development, and probability of survival.
Received: 12 August 1996 / Accepted: 26 August 1996 相似文献
734.
In French Guiana, parabiotic societies (natural mixed colonies) are frequently found in ant gardens. Crematogaster limata parabiotica (Myrmicinae), often associated with Camponotus femoratus (Formicinae), was found for the first time in parabiosis with ponerine ants: Pachycondyla goeldii and Odontomachus mayi. A detailed study of the relationships between Cr. l. parabiotica and O. mayi showed that each species is aggressive towards allospecific or conspecific individuals belonging to another colony, but tolerates
allospecific individuals from the multi-species society. Studies of cuticular substances of the four ant species were made
using gas chromatography. The results showed that each species, living alone or in parabiosis, possesses a specific chemical
profile. Thus, the ants are able to recognise nestmate and non-nestmate individuals of the associated species, even though
their cuticular profiles are different. The hypothesis that the nestmate allospecific profile is learned is suggested to explain
this pattern of recognition.
Received: 5 June 1996 / Accepted after revision: 17 October 1996 相似文献
735.
Osmoregulatory ability of mature chum salmon (Oncorhynchus keta) during spawning migration was examined by following the changes in gill Na+, K+-ATPase activity and in the distribution and morphology of chloride cells. Mature chum salmon caught in Otsuchi Bay, northern
Honshu Island, Japan, died within 5 d in seawater (SW) in association with a marked increase in plasma osmolality, whereas
the fish transferred to fresh water (FW) maintained plasma osmolality efficiently. Gill Na+, K+-ATPase activity decreased in both SW-maintained and FW-transferred fish. Well-developed chloride cells, identified by immunocytochemical
staining specific for Na+, K+-ATPase, were present mainly in the filament epithelium of immature fish caught in the ocean. In mature fish caught in the
bay, however, additional chloride cells were also found in the lamellar epithelium. The number of filament chloride cells
decreased markedly in the mature fish both in SW and in FW, whereas the number of lamellar chloride cells was maintained.
These results suggest that the loss of hypoosmoregulatory ability in mature chum salmon may be attributable to the decrease
in filament chloride cells and associated decrease in gill Na+, K+-ATPase activity, and also that appearance of lamellar chloride cells may be preparatory to the forthcoming upstream migration.
Received: 14 April 1997 / Accepted: 5 May 1997 相似文献
736.
L. E. C. Conceição T. van der Meeren J. A. J. Verreth M. S. Evjen D. F. Houlihan H. J. Fyhn 《Marine Biology》1997,129(2):255-265
The present paper studied the influence of different food regimes on the free amino acid (FAA) pool, the rate of protein
turnover, the flux of amino acids, and their relation to growth of larval turbot (Scophthalmus maximus L.) from first feeding until metamorphosis. The amino acid profile of protein was stable during the larval period although
some small, but significant, differences were found. Turbot larvae had proteins which were rich in leucine and aspartate,
and poor in glutamate, suggesting a high leucine requirement. The profile of the FAA pool was highly variable and quite different
from the amino acid profile in protein. The proportion of essential FAA decreased with development. High contents of free
tyrosine and phenylalanine were found on Day 3, while free taurine was present at high levels throughout the experimental
period. Larval growth rates were positively correlated with taurine levels, suggesting a dietary dependency for taurine and/or
sulphur amino acids. Reduced growth rates in Artemia-fed larvae were associated with lower levels of free methionine, indicating that this diet is deficient in methionine for
turbot larvae. Leucine might also be limiting turbot growth as the different diet organisms had lower levels of this amino
acid in the free pool than was found in the larval protein. A previously presented model was used to describe the flux of
amino acids in growing turbot larvae. The FAA pool was found to be small and variable. It was estimated that the daily dietary
amino acid intake might be up to ten times the larval FAA pool. In addition, protein synthesis and protein degradation might
daily remove and return, respectively, the equivalent of up to 20 and 10 times the size of the FAA pool. In an early phase
(Day 11) high growth rates were associated with a relatively low protein turnover, while at a later stage (Day 17), a much
higher turnover was observed.
Received: 19 March 1997 / Accepted: 14 April 1997 相似文献
737.
Mudball-building cirratulid polychaetes have been described previously only from the southern California margin. During a
study of oxygen minimum-zone benthos in fall 1994, we observed dense aggregations of agglutinated mudballs at 840 to 875 m
on the Oman margin in the northwest Arabian Sea. These were inhabited, and probably constructed, by a cirratulid polychaete
species in the genus Monticellina. The mudballs were cigar-shaped, 4.5 to 25 mm long, and positioned vertically so as to protrude several millimeters above
the sediment–water interface. Total mudball densities were ∼16 000 m−2. Occupied mudballs occurred at densities of 2 112 m−2; 89% were in the uppermost 2 cm of sediment, and no occupied mudballs were found below 10 cm. Organisms other than the cirratulid
were present on 1.7% of the mudballs examined, and included epizoic polychaetes, agglutinated and calcareous Foraminifera.
Various polychaetes, a nemertean and nematodes were found inside tests. Mudball abundance exhibited positive associations
with densities of several paraonid polychaete species, and with densities of burrowing and subsurface-deposit-feeding polychaetes.
Negative associations were observed between mudballs and three tube-building taxa (two polychaetes and an amphipod). Mudball-inhabiting
cirratulids are abundant in at least two low-oxygen, margin settings. We expect further sampling of bathyal environments to
yield additional systems in which cirratulid mudballs are common. Such observations are valuable because mudballs appear to
represent a significant source of heterogeneity that can influence macrofaunal community structure in deep-sea sediments.
Received: 15 January 1997 / Accepted: 30 January 1997 相似文献
738.
739.
The marine planktonic diatom Chaetoceros anastomosans, which was isolated from Sagami Bay, was used for a study of resting spore formation mechanisms in batch culture experiments.
Vegetative cells could grow at salinities ranging from 20.7 to 45.5‰, and resting spore formation was enhanced significantly
in nitrate-depleted, high salinity media (40.0 to 45.5‰). The rate of resting spore formation (1.9 d−1) was comparable to the specific growth rate (1.8 d−1) of vegetative cells in the exponential growth phase in normal salinity medium. The size of resting spores formed under high
salinity conditions was smaller than that of spores formed in normal salinity media. Unlike vegetative cells, resting spores
seemed to possess some mechanisms to survive over a wider range of salinities by resisting bacterial attacks on their cell
walls.
Received: 4 August 1996 / Accepted: 27 August 1996 相似文献
740.
Marc Nagtegaal Thomas A. Ternes Wolfram Baumann Roland Nagel 《Environmental Sciences Europe》1997,9(2):79-86
A method was developed for the analysis of fish samples to detect sunscreen agents (SSA) together with organochlorides (PCB, DDT) in different fish tissues. Detection limits of the compounds analyzed are in the range of ng/kg and vary between 40 and 90 ng/kg fillet. Recovery rates range from 78 to 104%. The contamination of water and fish with SSA in Meerfelder Maar lake, the Eifel, Germany was investigated in 1991 and 1993 and allowed the identification and quantification of six different SSA in the fish. The sum of SSA concentrations in perch taken in the summer of 1991 was 2.0 mg/kg lipid and 0.50 mg/kg lipid was found in roach sampled during the summer of 1993. Both species were contaminated with SSA and organochlorides to the same ranges as PCB and DDT. Even in the fillet of roach taken from three other lakes in Germany, methylbenzylidene camphor, a lipophilic SSA, was detected. These results indicate that SSA are wide-spread in German lakes. Therefore, they can be seen as a new group of relevant environmental chemicals. In the investigated lakes, the concentrations of the SSA in water were mostly below the detection limits. Thus, fish can be used as a biomonitor for these lipophilic compounds. Due to the lack of toxicological data for aquatic organisms, an ecotoxicological assessment is impossible at the moment. 相似文献