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91.
塔里木河流域生态脆弱性评价研究 总被引:49,自引:1,他引:48
塔里木河流域受自然及人为因素的影响,局部地区生态退化问题突出,从景观生态学的干扰性质理论和恢复生态学的观点出发,选择水资源系统、土地资源系统及植被资源系统及其10个综合性敏感因子对流域生态的敏感性及恢复力进行分析,并确定敏感因子的定量指标,定性代码及其权重和阈值,通过算术对数插值对敏感因子实际值进行规范化处理,并构建生态胁迫度。结果表明,塔里木河三源流阿克苏河流域、叶尔羌河流域、和田河流域及于流区的上、中、下游区生态胁迫度分别为0.13、0.25、0.30、0.31、0.57及0.84,在评价分级标准的限定下,其对应的生态脆弱性程度依次为轻微脆弱、一般脆弱、一般脆弱、一般脆弱、中等脆弱及严重脆弱。 相似文献
92.
93.
In the cooperatively breeding red-cockaded woodpecker (Picoides borealis), male helpers are subordinate to male breeders and do not mate with females, even when unrelated to the breeding female
within their group or through extra-group matings, yet exhibit reproductive hormone profiles similar to those of breeders.
We investigated whether reproduction might be suppressed in helper males via high levels of the stress hormone corticosterone.
We also examined effects of group size and season on corticosterone levels by comparing baseline and maximal plasma levels
of corticosterone between helper males and breeding males, and among helper males and breeders of both sexes living in groups
of different sizes throughout the reproductive cycle. We also measured plasma levels of estrogen, progesterone, and testosterone
to examine other potential hormonal differences between helpers and breeders. Male status did not explain variation in any
hormones; therefore, our data do not support the hypothesis that helper males are reproductively suppressed via corticosterone
or the other hormones investigated. However, the presence of two or more helper males in a group tended to reduce baseline
corticosterone in breeding and helper males, but not breeding females, suggesting that helper males reduce parental effort
of other male group members. Seasonally, maximal corticosterone peaked during the nestling provisioning phase for breeding
and helper males, but not breeder females, suggesting that males show an increased response to stressors posing a potential
threat to survival of offspring. 相似文献
94.
Impact of Hazardous Exposure to Metals in the Nile and Delta Lakes on the Catfish, Clarias lazera 总被引:3,自引:0,他引:3
K. G. Adham I. F. Hassan N. Taha Th. Amin 《Environmental monitoring and assessment》1999,54(2):107-124
The impact of metal pollution in the Nile and Delta lakes was studied in Clarias lazera. Lake Edku is grouped as the site highest in metal concentrations. Compared to Lakes Maryût and Edku, the Nile stations displayed lower levels of metal contamination signifying their selection as reference sites. Metals were accumulated most by the liver, less by muscles and least by serum. Iron showed the highest bioconcentration factors (BCF) in liver, muscles or serum compared to other metals. Even after the refinement of the surrounding water, fish seem to uphold the metals that have been previously ingested. Mercury, in particular, seems to eventually reside in muscles rather than in liver. The positive relationship between total serum protein and metal contents may indicate the formation of specific metal-binding proteins. Meanwhile, serum hyperalbuminemia in polluted fish is probably a shock response towards the high stress index induced by metals. The hypothesis that most of serum copper is bound to ceruloplasmin is documented also in C. lazera. Moderate, but not extennsive, exposure to metals was quite stimulatory to liver alkaline phosphatase (AP) biosynthesis. AP could, thus, be considered as a promising bioindicator for assessing sublethal water intoxicosis. 相似文献
95.
Bährs H Menzel R Kubsch G Stösser R Putschew A Heinze T Steinberg CE 《Chemosphere》2012,87(11):1193-1200
Dissolved organic matter (DOM) has been shown to affect phytoplankton species directly. These interactions largely depend on the origin and molecular size of DOM and are different in prokaryotes and eukaryotes. In a preceding study, however, two humic substance preparations did not adversely affect coccal green algae or cyanobacterial growth even at high concentrations of dissolved organic carbon (DOC). These results contradicted previous findings, showing a clear, negative response of different phototrophs to much lower DOC concentrations. To test whether or not at least defined building blocks of humic substances (HSs) are effective algicidal structures, we enriched two humic preparations with hydroquinone and p-benzoquinone, respectively, and exposed two different green algae, Pseudokirchneriella subcapitata and Monoraphidium braunii, and two cyanobacterial species, Synechocystis sp. and Microcystis aeruginosa, to the unmodified and enriched HSs. As response variables, growth rates in terms of biomass increase, chlorophyll-a content, and photosynthetic yield were measured. The highest concentration (4.17 mM DOC) of the modified HSs clearly inhibited growth; the cyanobacterial species were much more sensitive than the green algal species. However, realistic ecological concentrations did not adversely affect growth. Aerating the exposure solution for 24 h strongly reduced the inhibitory effect of the modified HSs. The algicidal effect was obviously caused by monomers and not by polymerised high molecular weight HSs themselves. Furthermore, the maximum quantum yield (Φ PSII max) was stimulated in the green algal species by low and medium DOC concentrations, but reduced in the cyanobacterial species upon exposure to higher HS concentrations. The quinone- and phenol-enriched HSs only showed algicidal activity at high concentrations of 4.17 mM DOC and lost their effects over time, presumably by oxidation and subsequent polymerisation. This study confirms that the applied humic substances themselves are not effective algicides even if enriched in effective structures. 相似文献
96.
Tausz M Landmesser H Posch S Monschein S Grill D Wienhaus O 《Environmental monitoring and assessment》2007,128(1-3):75-82
In this work we measured a set of antioxidative and photoprotective compounds (chlorophylls, carotenoids, tocopherol, ascorbate
and glutathione), which were suggested previously as stress markers in conifer needles, at two spruce forest sites at different
elevation in Saxony, Germany. Most variables differed significantly between current and 1-year-old needles, but only the content
of the xanthophyll cycle per mg total chlorophyll and the oxidation state of glutathione were significantly different between
the sites. We applied principal component analysis (PCA) to address the question if underlying accumulated variables are similar
to the ones found in spruce needles across Alpine elevation profiles and/or for pines in Mediterranean ecosystems. Four principal
components (accumulated variables, PC) representing 68% of the total variance of the dataset were extracted. PC 1 encompassed
total chlorophyll, lutein, and β-carotene contents, PC 2 combined the epoxidation state of xanthophylls, ascorbate content
and redox state, and glutathione content, PC 3 represented the content of xanthophylls and the redox state of glutathione,
and PC 4 encompassed the content of α-carotene and the epoxidation state of xanthophylls. Only PC 3 was significantly different
between sites. The PCA structure shows many similarities to corresponding findings in studies on spruce in mountain forests
in the Alps and pines in Mediterranean systems. This corroborates the interpretation of PCs as indicative for underlying physiological
processes. However, separation of the two investigated sites by PCs was in the present case study not superior to the separation
by single input variables. 相似文献
97.
Tree and stand growth of mature Norway spruce and European beech under long-term ozone fumigation 总被引:1,自引:0,他引:1
Hans Pretzsch Jochen Dieler Philip Wipfler 《Environmental pollution (Barking, Essex : 1987)》2010,158(4):1061-1070
In a 50- to 70-year-old mixed stand of Norway spruce (Picea abies (L.) Karst.) and European beech (Fagus sylvatica L.) in Germany, tree cohorts have been exposed to double ambient ozone (2×O3) from 2000 through 2007 and can be compared with trees in the same stand under the ambient ozone regime (1×O3). Annual diameter growth, allocation pattern, stem form, and stem volume were quantified at the individual tree and stand level. Ozone fumigation induced a shift in the resource allocation into height growth at the expense of diameter growth. This change in allometry leads to rather cone-shaped stem forms and reduced stem stability in the case of spruce, and even neiloidal stem shapes in the case of beech. Neglect of such ozone-induced changes in stem shape may lead to a flawed estimation of volume growth. On the stand level, 2×O3 caused, on average, a decrease of 10.2 m3 ha−1 yr−1 in European beech. 相似文献
98.
99.
Comparison of membrane fouling during short-term filtration of aerobic granular sludge and activated sludge 总被引:3,自引:0,他引:3
Aerobic granular sludge was cultivated adopting internal-circulate sequencing batch airlift reactor.The contradistinctive experiment about short-term membrane fouling between aerobic granular sludge system and activated sludge system were investigated.The membrane foulants was also characterized by Fourier transform infrared(FTIR)spectroscopy technique.The results showed that the aerobic granular sludge had excellent denitrification ability;the removal efficiency of TN could reach 90%.The aerobic granular sludge could alleviate membrane fouling effectively.The steady membrane flux of aerobic granular sludge was twice as much as that of activated sludge system.In addition,it was found that the aerobic granular sludge could result in severe membrane pore-blocking, however,the activated sludge could cause severe cake fouling.The major components of the foulants were identified as comprising of proteins and polysaccharide materials. 相似文献
100.
Fossi MC Casini S Marsili L 《Environmental science and pollution research international》2006,13(3):204-207
- DOI: http://dx.doi.org/10.1065/espr2006.01.018
Background, Aims and Scope
Man-made Endocrine Disruptors (EDs) range across all continents and oceans. Some geographic areas are potentially more threatened
than others: one of these is the Mediterranean Sea. Levels of some xenobiotics are much higher here than in other seas and
oceans. In this paper we review the final results of a project in which the hypothesis that Mediterranean top predator species
(such as large pelagic fish and marine mammals) are potentially at risk due to EDs was investigated.
Methods In a four-year survey on the Mediterranean population of swordfish (Xiphias gladius), the potential toxicological effects
of organochlorine compounds (OCs) on specimens of swordfish and tuna fish (Thunnus thynnus thynnus), caught in the spawning
seasons from 1999 to 2002 in the Straits of Messina, Sicily (Italy), were investigated using vitellogenin (Vtg), Zona radiata
proteins (Zrp), and cytochrome P4501A (CYP1A) activities (EROD, BPMO). Tissues (skin and blubber) were obtained from Stenella
coeruleoalba, Tursiops truncatus, Delphinus delphis and Balaenoptera physalus from the western Ligurian Sea, between Corsica
and the French-Italian coast, and Ionic Sea using biopsy darts launched with a crossbow. Benzo(á)pyrene monoxigenase (BPMO)
activity was mesured in biopsies and cholrinated hydrocarbon levels were detected.
Results and Discussion We illustrate the need to develop and apply sensitive methodological tools, such as biomarkers (Vitellogenin, Zona Radiata
proteins and CYP1A activities) for evaluation of toxicological risk in Xiphias gladius and Thunnus thynnus thynnus), and nondestructive
biomarkers (CYP1A activities and fibroblast cell culture in skin biopsy), for the hazard assessment of threatened marine mammals
species (Stenella coeruleoalba, Tursiops truncatus, Delphinus delphis and Balaenoptera physalus) exposed to EDs.
Conclusion The present research shows that: a) Vtg and Zrp can be used as diagnostic tools for fish stocks hazard assessment in the
Mediterranean Sea; b) that CYP1A1 (BPMO) induction in cetaceans skin biopsy may be an early sign of exposure to EDs such as
OCs and a potential alert for transgenerational effects.
Recommendation and Outlook This research represents a warning signal of the potential reproductive alterations in marine top predators and suggest the
need for continuous monitoring to avoid reductions in population and biodiversity in the Mediterranean Sea. 相似文献