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521.
Glenn Courtenay William Gladstone Marcus Scammell Ren��e Kidson Julie Wood 《Environmental monitoring and assessment》2011,175(1-4):685-697
The influence of ambient water quality on the settlement of barnacles and the green alga Enteromorpha spp. to an artificial substratum in the estuaries of Sydney, Australia, was investigated to test the efficacy of both groups of organisms as indicators of changes in water quality due to urban stormwater runoff and/or sewage overflows. Wooden settlement panels were immersed for 4 months on 17 occasions between 1996 and 2005 at 11 locations known to vary in water-quality parameters (conductivity, total uncombined ammonia, oxidised nitrogen, total nitrogen, filterable phosphorus, total phosphorus, faecal coliforms and chlorophyll-a) and ambient meteorological conditions (total rainfall, maximum rainfall). Water-quality data were collected during the time that the settlement panels were deployed. Cover of barnacles was highly variable among locations (range 1.2?C55.2%). Hierarchical partitioning found that chlorophyll-a, total phosphorus and total nitrogen had significant independent positive effects on barnacle cover. Together, these variables explained 26% of the variation in barnacle cover. Mean cover of Enteromorpha spp., however, did not vary significantly among locations suggesting that other potentially more important factors are influencing its settlement and growth. The results of this study suggest that barnacle cover is likely to be a useful indicator of some components of water quality. 相似文献
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Gültekin Çoşkun Ali Sarıışık 《International journal of occupational safety and ergonomics》2019,25(3):443-457
This study was conducted to determine the most appropriate surface processing techniques (SPT), environmental conditions (EC) and surface roughness (SR) to minimize the risk of slipping when pedestrians walk on a floor covering of rocks barefoot and with shoes. Coefficients of friction (COFs) and values of SR were found using five different types of rocks, four SPT and two (ramp and pendulum) tests. Results indicate that the parameters which affect the COF values of rocks include SR, EC and SPT. Simple linear regression was performed to examine the relationship between the values of the COF and the SR. The value of the COF was identified as R2?≥?0.864. Statistical results, which are based on experimental measurements, show that rocks are classified according to their safe use areas depending on their COF and SR values. 相似文献
526.
Peter Vr?ansky Du?an Chorvát Ingo Fritzsche Miroslav Hain Robert ?ev?ík 《Die Naturwissenschaften》2012,99(9):739-749
Bioluminescence is a common feature of the communication and defence of marine organisms, but this phenomenon is highly restricted in the terrestrial biota. Here, we present a geographical distribution of only the third order of luminescent insects—luminescent cockroaches, with all 13 known and/or herein reported new living species (based on deposited specimens). We show that, for the first time, photo-characteristics of three examined species are nearly identical with those of toxic luminescent click beetles, which they mimic. These observations are the evidence for the mimicry by light—a new type of defensive, Batesian and interordinal mimicry. Our analysis surprisingly reveals an evolutionary novelty of all living luminescent insects, while in the sea (and possibly in the soil) luminescence is present also phylogenetically in very primitive organisms. 相似文献
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Michael Komárek Aleš Vaněk Radka Sudová Václav Tejnecký 《Environmental pollution (Barking, Essex : 1987)》2010,158(7):2428-2438
Incubation and pot experiments using poplar (Populus nigra L. cv. Wolterson) were performed in order to evaluate the questionable efficiency of EDDS-enhanced phytoextraction of Cu from contaminated soils. Despite the promising conditions of the experiment (low contamination of soils with a single metal with a high affinity for EDDS, metal tolerant poplar species capable of producing high biomass yields, root colonization by mycorrhizal fungi), the phytoextraction efficiency was not sufficient. The EDDS concentrations used in this study (3 and 6 mmol kg−1) enhanced the mobility (up to a 100-fold increase) and plant uptake of Cu (up to a 65-fold increase). However, despite EDDS degradation and the competition of Fe and Al for the chelant, Cu leaching cannot be omitted during the process. Due to the low efficiency, further research should be focused on other environment-friendly methods of soil remediation. 相似文献
529.
Adam Dušek Luděk Bartoš František Sedláček 《Behavioral ecology and sociobiology》2011,65(12):2209-2217
The issue of adaptive adjustment of offspring sex ratio (proportion of male births) in polytocous mammals, producing several
offspring per litter, is controversial because females of these species can maximize their fitness mainly by adjusting offspring
number. To address this issue, we examined the effect of maternal condition at mating, experimentally decreased by pre-mating
food restriction, on the sex ratio variation in 137 female mice. We tested two basic sex allocation hypotheses plausible for
polytocous mammals: (1) the Myers hypothesis, predicting that cheaper sex should be favored in poor environmental conditions
to maximize offspring number; and (2) the Williams hypothesis, predicting maximum fitness returns by adjusting size- and sex-specific
composition of the litter according to the maternal condition. The food-restricted mothers produced larger litters with a
higher proportion of cheaper daughters than the control mothers. By contrast, the control mothers optimized size and sex composition
of the litter according to their weight at mating. In addition, the offspring of the food-restricted mothers suffered less
from pre-weaning mortality than those of the control mothers. Therefore, when comparing the groups, the Myers hypothesis had
a general significance while the Williams hypothesis was plausible only for the control mothers. Furthermore, some of the
food-restricted mothers partly coped with the pre-mating food restriction and increased the proportion of sons in the litter
with the increasing maternal weight loss (during the period of food restriction). The sex ratio variation was thus a result
of three sex allocation strategies depending on the maternal condition at mating. 相似文献
530.
Marek Špinka Gudrun Illmann Jiří Haman Petr Šimeček Jitka Šilerová 《Behavioral ecology and sociobiology》2011,65(7):1447-1457
In domestic pigs, about 20% of nursing episodes end without milk transfer (non-nutritive nursings, NNNs). The function of
NNNs has not been satisfactorily explained yet. Here, we suggest that NNNs may be a part of an honest signaling system that
enables the sow to provide more frequent nutritive nursings (NNs) to those litters that can prove their need through exceptionally
frequent milk ejection solicitations. We further propose that the system is kept stable through the accelerating costs attached
to the solicitation in the form of NNNs. Based on this hypothesis, we predicted that (P1) with an increasing number of all
nursings (ALL = NNNs + NNs) the number of NNs should increase and that (P2) with an increasing number of ALL the proportion
of NNNs should increase. We tested P1 and P2 using a meta-analysis applied to data from eight studies that recorded the number
of NNs and NNNs in domestic pigs. We confirmed both P1 (NNs increasing with ALL) and P2 (proportion of NNNs increasing with
ALL). In combination, these results show a steeply accelerating cost of each additional nutritive nursing that piglets instigate.
This cost sets limits to the piglets' ability to solicit higher maternal investment through more frequent nursing solicitations. 相似文献