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151.
The activity of four enzymes, including GOT-1, has been investigated in the erythrocytes of a 10q→24qter trisomic fetus. Analyses have been performed on a feto-maternal blood mixture sampled by fetoscopy and on red cells obtained by cardiac puncture, following therapeutic abortion. The demonstration of a 40 percent increase of GOT-1 activity, as compared to normal fetuses of similar gestational age, suggests that gene dosage studies may be a useful confirmatory technique in prenatal diagnosis of unbalanced chromosomal aberrations. Practical application of a similar diagnostic approach is conditioned by (1) precise characterization of fetal chromosome imbalance; (2) confirmed assignment of the gene locus coding for the gene product under investigation; (3) evidence of a linear proportionality between gene dose and concentration of the gene product in patients with the same chromosome imbalance detected in the fetus; (4) knowledge of the range of normal variation at different weeks of gestation of the enzyme activity to be tested in the fetus; (5) safety of fetal sampling procedure. 相似文献
152.
We report a case in which a discrepancy emerged between the prenatal diagnosis of female chromosomal sex and male sex at ultrasound examination. The FSH dosage performed on an amniotic fluid sample previously stored confirmed the male phenotype of the fetus. The effectiveness of the AF-FSH level dosage in prenatal diagnosis was taken into consideration. 相似文献
153.
A routine study of the fetal karyotype was performed on samples obtained at 64 fetoscopic procedures. In 13 cases only pure amniotic fluid was available for the cultures, while in the remaining 51 cases the chromosome analysis was carried out on PHA-stimulated lymphocyte microcultures set up with any excess fetal blood above the requirements for globin-chain synthesis. Karyotype could be determined on fetal lymphocytes in 44 cases (86 per cent). All the fetuses were chromosomally normal. This experience shows that cytogenetic analysis using microaliquots of fetal blood is a relatively simple technique which should be introduced into routine prenatal diagnosis by fetoscopy. 相似文献
154.
Martínez E Llobet I Lacorte S Viana P Barceló D 《Journal of environmental monitoring : JEM》2002,4(2):253-257
The present study focused on monitoring the concentration of 14 halogenated volatile organic compounds in surface waters, including sea, estuarine, river water and industrial effluents in order to determine the most ubiquitous compounds and their concentration levels, which were used to establish their geographical and temporal distribution. EPA Method 502, based on purge and trap techniques, was used. In this method volatile organic pollutants are extracted (purged) from the water sample by bubbling inert gas through the aqueous sample. Purged sample components are trapped in a cartridge containing the polymeric sorbent Tenax and, thereafter, the cartridge is heated and backflushed with helium to desorb the trapped sample components directly into a gas chromatograph with electron capture detector (GC-ECD). The linearity range of the method varied from 0.1 to 4 microg L(-1) with a limit of detection at the low microg L(-1) level. The present study consisted of a monthly monitoring of 46 points throughout Portugal, during 14 months. Chloroform was found in 50% of the samples analyzed, its presence being correlated to both agricultural and industrial activities. Other compounds detected were tetrachloroethylene, trichloroethylene, carbon tetrachloride and 1,2,4 trichlorobenzene, which were present in 10-20% of the samples at concentrations up to 18 microg L(-1). 1,1,2,2-Tetrachloroethane and its degradation product 1,1,2-trichloroethane were found in 5% of the samples, the levels of the latter being higher than those of the parent compound in most samples. Sporadic high concentrations of some volatile halogenated organic compounds were attributed to local uses as solvents. 相似文献
155.
The sources of carbon and the dietary habits of Brachidontes pharaonis (Mollusca, Bivalvia), a new Lessepsian entry in the western Mediterranean, living in a cooling vat of a saltworks system in western Sicily (MED), were assessed by estimating throughout a season the relative abundance of a stable carbon isotope (13C) in particulate organic matter (POM), sedimentary organic matter (SOM), primary organic matter sources (seagrasses, sand microflora, macroalgae), Brachidontes pharaonis and its biodeposition material. In the saltworks the most enriched primary food source potentially fuelling the saltworks food web was Cymodocea nodosa (seasonal average –7.9±0.6), Laurencia papillosa and Cystoseira sp., which represented the predominant macroalgae (seasonal average –19.0±1.0) and sand microflora 13C (–14.7±0.11). POM annual mean 13C was –17.4±0.9, and that of SOM was –17.0±2.3. The seasonal mean isotopic value of B. pharaonis was –14.7±0.7; while its faeces was more depleted (–17.7±2.4), while the pseudofaeces (–14.6±3.6) was similar to somatic B. pharaonis in composition. Our study showed that Brachidontes assimilated mostly mixed sedimentary organic carbon re-arranged via a detritus route dominated mainly by macroalgae and sand microflora and that it was able to exploit almost all the predominant carbon sources available in its colonised environment both directly (sand microflora) and indirectly via the POM/SOM detritus route. These carbon sources incorporated most of the environmental variability relative to the isotopic composition of primary producers (about –11 throughout the year).Communicated by R. Cattaneo-Vietti, Genova 相似文献
156.
Carlos Carreras Sara Pont Fulvio Maffucci Marta Pascual Anna Barceló Flegra Bentivegna Luis Cardona Ferràn Alegre Manuel SanFélix Gloria Fernández Alex Aguilar 《Marine Biology》2006,149(5):1269-1279
The analysis of mitochondrial DNA in loggerhead sea turtles (Caretta caretta) from eight foraging grounds in the Mediterranean and the adjoining Atlantic revealed deep genetic structuring within the western Mediterranean. As a consequence, the foraging grounds off the North-African coast and the Gimnesies Islands are shown to be inhabited mainly by turtles of the Atlantic stocks, whereas the foraging grounds off the European shore of the western Mediterranean are shown to be inhabited mainly by turtles from the eastern Mediterranean rookeries. This structuring is explained by the pattern of sea surface currents and water masses and suggests that immature loggerhead sea turtles entering the western Mediterranean from the Atlantic and the eastern Mediterranean remain linked to particular water masses, with a limited exchange of turtles between water masses. As the north of the western Mediterranean comprises mostly individuals from the highly endangered eastern Mediterranean rookeries, conservation plans should make it a priority to reduce the mortality caused by incidental by-catch in these areas. 相似文献
157.
Metabolic relationships between symbiotic cyanobacteria and host sponge have been investigated in the marine species Chondrilla nucula and Petrosia ficiformis (collected in the Ligurian Sea in 1992). DNA, RNA, total protein, cytosolic protein, total sugar, cytosolic sugar, total lipid, nonprotein sulfhydryl groups, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were assayed in cortex-free sponge tissue, where cyanobacteria are all but absent. For both species, biochemical parameters were determined in specimens living in illuminated habitats and in dark caves, where sponges are virtually aposymbiotic for cyanobacteria. As C. nucula is unable to colonize dark sites, specimens of this species were artificially transferred to a cave and maintained in dark conditions for 6 mo. Results showed that in the absence of light (i.e., in the absence of cyanobacteria) C. nucula undergo metabolic collapse and thiol depletion. In contrast, P. ficiformis activates heterotrophic metabolism and mechanisms which balance the loss of cell reducing power. This suggests that cyanobacteria effectively participate in controlling the redox potential of the host cells by the transfer of reducing equivalents. Only P. ficiformis is capable of counteracting, by means of heterotrophic metabolism, the loss of the contribution from symbionts which is caused by dark conditions. This explains the differences in the ecological requirements of the two species. Because cyanobacterial symbionts release fixed carbon in the form of glycerol and other small organic phosphate (Wilkinson 1979), a model based on the glycerol 3-phosphate shuttle (typically occurring in chloroplasts and mitochondria) is suggested. The mechanism proposed appears to be an ancient biochemical adaptation which arose among ancestral symbiotic systems, and further developed in the relationships between endosymbiotic organelles and cytoplasm. 相似文献
158.
Seasonal differences in the locomotor activity pattern of Podarcis sicula held in constant conditions in the laboratory were found to be associated with systematic differences in both the freerunning period of locomotor rhythms () and the circadian activity time (). In order to establish whether the pineal played a role in the control of seasonal changes in circadian parameters, we examined the effects of pinealectomy in constant conditions on the locomotor behavior of lizards displaying the bimodal activity pattern typical of summer. In most lizards pinealectomy lengthened , shortened and abolished the bimodal activity pattern. Pinealectomy induced a sudden transition from the typical locomotor behavior of summer, characterized by a marked bimodal pattern, short and long , to the typical locomotor behavior of autumn, characterized by a unimodal pattern, a long and short . These results demonstrate that the pineal plays a central role in the seasonal reorganization of the circadian system that occurs in P. sicula. 相似文献
159.
Nitrous oxide nitrification and denitrification 15N enrichment factors from Amazon forest soils. 总被引:1,自引:0,他引:1
Tibisay Pérez Diana Garcia-Montiel Susan Trumbore Stanley Tyler Plínio de Camargo Marcelo Moreira Marisa Piccolo Carlos Cerri 《Ecological applications》2006,16(6):2153-2167
The isotopic signatures of 15N and 18O in N2O emitted from tropical soils vary both spatially and temporally, leading to large uncertainty in the overall tropical source signature and thereby limiting the utility of isotopes in constraining the global N2O budget. Determining the reasons for spatial and temporal variations in isotope signatures requires that we know the isotope enrichment factors for nitrification and denitrification, the two processes that produce N2O in soils. We have devised a method for measuring these enrichment factors using soil incubation experiments and report results from this method for three rain forest soils collected in the Brazilian Amazon: soil with differing sand and clay content from the Tapajos National Forest (TNF) near Santarém, Pará, and Nova Vida Farm, Rond?nia. The 15N enrichment factors for nitrification and denitrification differ with soil texture and site: -111 per thousand +/- 12 per thousand and -31 per thousand +/- 11 per thousand for a clay-rich Oxisol (TNF), -102 per thousand +/- 5 per thousand and -45 per thousand +/- 5 per thousand for a sandier Ultisol (TNF), and -10.4 per thousand +/- 3.5 per thousand (enrichment factor for denitrification) for another Ultisol (Nova Vida) soil, respectively. We also show that the isotopomer site preference (delta15Nalpha - delta15Nbeta, where alpha indicates the central nitrogen atom and beta the terminal nitrogen atom in N2O) may allow differentiation between processes of production and consumption of N2O and can potentially be used to determine the contributions of nitrification and denitrification. The site preferences for nitrification and denitrification from the TNF-Ultisol incubated soils are: 4.2 per thousand +/- 8.4 per thousand and 31.6 per thousand +/- 8.1 per thousand, respectively. Thus, nitrifying and denitrifying bacteria populations under the conditions of our study exhibit significantly different 15N site preference fingerprints. Our data set strongly suggests that N2O isotopomers can be used in concert with traditional N2O stable isotope measurements as constraints to differentiate microbial N2O processes in soil and will contribute to interpretations of the isotopic site preference N2O values found in the free troposphere. 相似文献
160.
Albert Llausàs Anna Ribas Diego Varga Josep Vila 《Agriculture, ecosystems & environment》2009,129(1-3):73-82
During the last 50 years, mechanisation of the rural environment, and, more recently, the Common Agricultural Policy have led to profound changes in agrarian landscapes throughout Europe, and in particular in the rich and diverse Mediterranean landscapes (Meeus et al., 1990). In the north-east of the Iberian Peninsula, a small area of hedgerow landscape persists as a remnant of what was once an important centre for livestock production. This paper presents the results of a study carried out in this area with the aim of clarifying the relationship between the structural change of this hedgerow landscape and the evolution of farming practices developed by its owners and workers. It also considers these farmers’ perceptions of their pastures, of their farms and of the region. Up to 61 statistically significant relationships were found between the physical landscape characteristic variables and the socio-economical variables. Results depict a hedgerow landscape determined by the combination of two management models. Here, and contrary to conclusions reported in similar literature, traditional pasture activity leads to a weaker hedgerow network than a farming model based on crop cultivation. Management guidance required to move from the current situation towards a hedgerow landscape supporting both biodiversity and agrarian activity is discussed. 相似文献