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291.
Muhammad?Shafiq Tahira?Shaukat Aisha?Nazir Firdaus-e-?BareenEmail author 《Environmental monitoring and assessment》2017,189(8):423
Kasur is one of the hubs of leather industry in the Punjab, Pakistan, where chrome tanning method of leather processing is extensively being used. Chromium (Cr) accumulation levels in the irrigation water, soil, and seasonal vegetables were studied in three villages located in the vicinity of wastewater treatment plant and solid waste dumping site operated by the Kasur Tanneries Waste Management Agency (KTWMA). The data was interpreted using analysis of variance (ANOVA), clustering analysis (CA), and principal component analysis (PCA). Interpolated surface maps for Cr were generated using the actual data obtained for the 30 sampling sites in each of the three villages for irrigation water, soil, and seasonal vegetables. The level of contamination in the three villages was directly proportional to their distance from KTWMA wastewater treatment plant and the direction of water runoff. The highest level of Cr contamination in soil (mg kg?1) was observed at Faqeeria Wala (37.67), intermediate at Dollay Wala (30.33), and the least in Maan (25.16). A gradational variation in Cr accumulation was observed in the three villages from contaminated wastewater having the least contamination level (2.02–4.40 mg L?1), to soil (25.16–37.67 mg kg?1), and ultimately in the seasonal vegetable crops (156.67–248.33 mg kg?1) cultivated in the region, having the highest level of Cr contamination above the permissible limit. The model used not only predicted the current situation of Cr contamination in the three villages but also indicated the trend of magnification of Cr contamination from irrigation water to soil and to the base of the food chain. Among the multiple causes of Cr contamination of vegetables, soil irrigation with contaminated groundwater was observed to be the dominant one. 相似文献
292.
293.
294.
Ting Zhang Wen-Long Yang She-Jun Chen Dian-Long Shi Hu Zhao Yi Ding Ye-Ru Huang Nan Li Yue Ren Bi-Xian Mai 《Environmental monitoring and assessment》2014,186(8):5285-5295
Polybrominated diphenyl ethers (PBDEs), organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) in 25 surface sediments in three cities (Nantong, Wuxi, and Suzhou) in the Yangtze River Delta, eastern China were measured. The mean concentrations were 378, 45.8, 1.98, 4,002 ng/g for PBDEs, OCPs, PCBs, and PAHs, respectively. Their levels in the sediments in the three cities were generally consistent with the city industrialization. PBDEs and OCPs were markedly dominated by deca-BDE (>90 %) and DDTs (>70 %). A principle component analysis of the analytes identified three major factors suggesting different sources of the contaminants in the sediments. PBDEs and the organic carbon in the sediments have common sources from industrial activities; whereas OCPs and PCBs, correlated with the second factor, were mainly from historical sources. The third factor with loadings of PAHs is indicative of various combustion sources. Ecological risk assessment indicated that the potential highest risk is from DDTs, for which 22 sites exceed the effects range low (ERL) values and three sites exceed the effects range median (ERM) value. 相似文献
295.
Ground-living spiders were studied using modified pitfall traps during several years in four characteristic habitats in Giant Mountains (Krkono?e Mts.), the High Sudetes, Czech Republic: alpine tundra, subalpine mire, tall-herb stand at the bottom of a glacial corrie, and decaying mountain spruce forest. Ecological and zoogeographical aspects of spider communities were analysed. The spider communities of alpine tundra, subalpine mire, and glacial corrie exhibited long-term stability, whereas the community of decaying mountain forest changed during observations. Small linyphiid spiders, dominating in mature forest, were gradually replaced by larger Iycosid and gnaphosid species. Zoogeographic characterization of mountain habitats was made based on species exhibiting disjunctive area. In contrast to plants, for spiders of boreal origin alpine tundra is the most important habitat for survival, followed by screes, mires, spruce forests, and corries. 相似文献
296.
297.
Combining field and laboratory work, this study investigated the reproductive cycle, aggregative behavior, spawning periodicity,
development and early growth of the sea star Henricia lisa living at bathyal depths off eastern Canada. Marked differences were found between individuals from ~1,300 and ~600 m deep.
The former had a male biased sex ratio and an aperiodic reproductive cycle, whereas the latter displayed an equal sex ratio
and a biannual breeding pattern. Furthermore, the maximum size was larger and female fecundity roughly five times higher in
shallower compared to deeper populations. In the tanks, aggregative behavior was recorded twice a year during the summer and
winter breeding periods. The onset of aggregations and spawning coincided with a temperature of 3–4°C. Males spawned first
and females typically responded inside 30–60 min. Between 12 and 20 eggs were retained to be brooded under the arched arms
of the female, whereas the remainder were broadcasted and developed without parental care. The fertilized eggs underwent a
first cleavage after 12 h, reached the brachiolaria stage in 1 month, became juveniles within 3–4 months and reached ~ 4 mm
in diameter after 14–17 months of growth. The embryos and juveniles developed at the same rate whether brooded or not, and
development of winter cohorts was typically slower due to lower prevailing temperatures. This study of H. lisa provides the first evidence of lecithotrophy in a seasonally breeding deep-sea echinoderm and of brooding in a deep-sea asteroid. 相似文献
298.
This study examines the composition and activity of the planktonic community during the polar night in the high Arctic Kongsfjord,
Svalbard. Our results are the first published evidence of bioluminescence among zooplankton during the Arctic polar night.
The observations were collected by a bathyphotometer detecting bioluminescence, integrated into an autonomous underwater vehicle,
to determine the concentration and intensity of bioluminescent flashes as a function of time of day and depth. To further
understand community dynamics and composition, plankton nets were used to collect organisms passing through the bathyphotometer
along with traditional vertical net tows. Additionally, using a moored bathyphotometer closed to the sampling site, the bioluminescence
potential itself was shown not to have a diurnal or circadian rhythm. Rather, our results provide evidence for a diel vertical
migration of bioluminescent zooplankton that does not correspond to any externally detectable changes in illumination. 相似文献
299.
Pascal D. Leroy Ahmed Sabri Fran?ois J. Verheggen Fr��d��ric Francis Philippe Thonart Eric Haubruge 《Chemoecology》2011,21(3):113-122
In natural environment, semiochemicals are involved in many interactions between the different trophic levels involving insects,
plants and hosts for parasitoids or prey for predators. These volatile compounds act as messengers within or between insect
species, inducing particular behaviours, such as the localisation of a source of food, the orientation to an adequate oviposition
site, the selection of a suitable breeding site and the localisation of hosts or prey. In this sense, bacteria have been shown
to play an important role in the production of volatile compounds which ones act as semiochemicals. This review, focusing
on the semiochemically mediated interactions between bacteria and insects, highlights that bacterial semiochemicals act as
important messengers for insects. Indeed, in most of the studies reported here, insects respond to specific volatiles emitted
by specific bacteria hosted by the insect itself (gut, mouthparts, etc.) or present in the natural environment where the insect
evolves. Particularly, bacteria from the families Enterobacteriaceae, Pseudomonaceae and Bacillaceae are involved in many
interactions with insects. Because semiochemicals naturally produced by bacteria could be a very interesting option for pest
management, advances in this field are discussed in the context of biological control against insect pests. 相似文献
300.
Elaine S. Carvalho Rubén J. Sánchez Maria I. B. Tavares álano C. Lam?nica 《Journal of Polymers and the Environment》2010,18(4):661-667
The chemical modification of Acrylamidomethyl Cellulose Acetate Propionate (AMCAP) was carried out by radical addition of
acrylic acid. The structural modification was confirmed with the aid of FTIR, MS and NMR techniques. Thermal properties of
hydrophilic cellulose derivative (AMCAP–H2O2) such as glass transition (Tg 153 °C) and thermal stability (372.7 °C) were determined by DSC and TGA techniques, respectively. These thermal properties
confirmed the introduction of carboxylic groups into AMCAP structure, which causes an impact in their properties. The AMCAP–H2O2 shows minor contact angle compared to AMCAP, giving a more hydrophilic characteristic, due to acrylic acid addition into
the side chains of AMCAP polymer. 相似文献