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191.
Karin Sundberg MD Steen Smidt-Jensen Claes Lundsteen Kirsten Agerbæk John Philip 《黑龙江环境通报》1993,13(12):1101-1110
Due to the low cell concentration, cultures from early amniotic fluid specimens usually require 2–3 weeks in culture prior to karyotyping. The purpose of this study was to evaluate the culture quality of amniotic fluid cells from early pregnancy, obtained by a new filter technique. The hypothetical advantage of the technique was that the increased cell yield might reduce the culture time before karyotyping. Culture quality was assessed by the number of colonies, the percentage of colonies containing mitoses in filter and control cultures, and the culture time. The setting was a consecutive clinical trial. One hundred samples were obtained from ongoing pregnancies at 11–14 weeks of gestation (mean 12·8 weeks). By circulating a mean of 26 ml of amniotic fluid through a cell filter system leading the cell-free fluid back to the amniotic cavity, the cell yield was increased in the sample of 7 ml corresponding to the dead space of the filter system. The culture results were compared with control cultures from 5 ml samples drawn from the same pregnancies prior to recirculation. The cultures from the first flushing of the filter system yielded 2·6 times more colonies and in total 4·2 times more colonies were found in the three cultures grown from each filter sample when compared with the control cultures. Moreover, the filter cultures showed significantly more colonies with mitoses. The mean culture time was 8·0 days for the filter cultures, from which the karyotypes were analysed. The controls would have needed more time in culture to fulfil the diagnostic criteria for karyotyping. One case of 47,XY, + 21 was found; the rest had normal karyotypes. We conclude that the filter technique improves the culture quality of early amniotic fluid samples and allows early arrest of the cultures. 相似文献
192.
Klaus Jung Karin Kaletta Helmut Segner Gerrit Schüürmann 《Environmental science and pollution research international》1999,6(2):72-76
A stable isotope15N-nitrogen test (ESIMA = Ecotoxicological Stable Isotope Metabolic Assay) was developed to assess biological effects and the
potential toxicological hazard of chemicals and contaminated environmental samples on plant metabolism. The assay measures
the effect of toxicants on the incorporation of a15N labelled tracer into the total nitrogen fraction (both the nonprotein and protein fraction) of plants. Segments ofPisum arvense epicotyls are used as test substrates because of their high metabolic activity. The plant material is incubated under standardised
conditions for two hours; subsequently15N incorporation is analysed by determining the15N abundance (15N atom-%) in the epicotyl segments.
The effects of toxicants are evaluated by comparing the15N incorporation rates of control tissue and epicotyl segments exposed to individual chemicals or complex environmental samples.
The specificity and sensitivity of effects as indicated by ESIMA were compared with effects as measured by two established
ecotoxicological bioassays, the pollen tube growth test using pollen ofNicotiana sylvestris and the bacterial luminescence inhibition test using pollen ofPhotobacterium phosphoreum. The results of the study clearly indicate the suitability of ESIMA for assessing toxic impacts on plant nitrogen metabolism.
Prof. Dr. habil. Hans Faust dedicated to his 70th birthday. 相似文献
193.
194.
Heidi Van den Broeck Karin Breugelmans Hans De Wolf Thierry Backeljau 《Marine Biology》2008,153(3):421-429
Planktonic developing organisms are generally assumed to be good dispersers showing little genetic structuring in neutral
markers. At first glance, this also applies to the planktonic developing periwinkle Tectarius striatus, an endemic gastropod from Macaronesia (i.e. Azores, Madeira, Canary Islands and Cape Verde Islands), where the only sign
of genetic structuring hitherto is provided by a non-significant allozyme/RAPD heterogeneity between the Cape Verde Islands
and the other archipelagos. However, partial sequences of the mitochondrial cytochrome b and cytochrome oxidase I genes now show that the Cape Verde Islands and the three other archipelagos have no haplotypes in
common, whereas the latter three do share several haplotypes. Nevertheless, this highly disjunct haplotype distribution does
not entail a phylogeographic break separating the haplotypes of both areas in two reciprocally monophyletic groups. This remarkable
geographic and phylogenetic structuring may be explained by assuming that T. striatus colonized the Macaronesian archipelagos in periods when sea levels were lower (and/or volcanic activity was higher), so that
seamounts peaked above sea level and could act as stepping-stones. Yet, after the last glacial period seamounts submerged,
thus preventing further stepping-stones mediated dispersal of T. striatus between the Cape Verde Islands and the other archipelagos, while not affecting dispersal among the latter because of their
closer proximity and connectivity. Hence, these contrasting patterns of neutral genetic variation in T. striatus show that genetic structuring in planktonic developing species may be far more complex than is usually assumed. 相似文献
195.
Introduced Pacific oysters (Crassostrea gigas) have shown rapid expansion in the Oosterschelde estuary, while stocks of native bivalves declined slightly or remained stable.
This indicates that they might have an advantage over native bivalve filter feeders. Hence, at the scale of individual bivalves,
we studied whether this advantage occurs in optimizing food intake over native bivalves. We investigated feeding current characteristics,
in which potential differences may ultimately lead to a differential food intake. We compared feeding currents of the invasive
epibenthic non-siphonate Pacific oyster to those of two native bivalve suspension feeders: the epibenthic siphonate blue mussel
Mytilus edulis and the endobenthic siphonate common cockle Cerastoderma edule. Inhalant flow fields were studied empirically using digital particle image velocimetry and particle tracking velocimetry.
Exhalant jet speeds were modelled for a range of exhalant-aperture cross-sectional areas as determined in the laboratory and
a range of filtration rates derived from literature. Significant differences were found in inhalant and exhalant current velocities
and properties of the inhalant flow field (acceleration and distance of influence). At comparable body weight, inhalant current
velocities were lower in C. gigas than in the other species. Modelled exhalant jets were higher in C. gigas, but oriented horizontally instead of vertically as in the other species. Despite these significant differences and apparent
morphological differences between the three species, absolute differences in feeding current characteristics were small and
are not expected to lead to significant differences in feeding efficiency. 相似文献
196.
Ximena E. Bernal Karin L. Akre Alexander T. Baugh A. Stanley Rand Michael J. Ryan 《Behavioral ecology and sociobiology》2009,63(9):1269-1279
We investigated the natural dynamics in a sexual signal that combines different call components and explored the role of call
complexity in sexual selection using a neotropical frog. Male túngara frogs, Physalaemus pustulosus, facultatively add up to seven short, multi-harmonic components (chucks) to the simple form of their calls (whines). Female
túngara frogs are preferentially attracted to whines with chucks over whines without chucks, and males also call more in response
to calls containing chucks. Because acoustic predators prefer complex calls, in the context of simple (no chucks) versus complex
(any number of chucks) calls, the variably complex call appears to have evolved in response to the opposing selective forces
of natural and sexual selection. There is no evidence, however, for the function of increasing the number of chucks within
complex calls. We tested two aspects of increasing call complexity: natural patterns of use of call types in males and how
both sexes respond to variation in multi-chuck calls. Males incrementally change call complexity by the addition or subtraction
of a single chuck and usually do not produce more than two chucks. Variation in call complexity, for calls with at least one
chuck, does not influence response calling in males or phonotaxis in females. Our results suggest that one reason for not
increasing call complexity beyond a single chuck is the diminishing effectiveness on the responses of both sexes.
This is a posthumous publication for A. Stanley Rand 相似文献
197.
Using a Pathways approach, controversies over environmental and natural resource management are viewed as expressions of alternative, or competing, pathways to sustainability. This supports deeper understanding of the underlying causes of natural resource management controversies. The framework is composed of two elements: the STEPS (Social, Technological, and Environmental Pathways to Sustainability) Pathways approach and frame analysis. Many sustainable development dilemmas are played out in specific places and consequently, the Pathways approach is integrated with a place-based frame analysis. The resulting framework guides empirical investigation in place-based contexts. This theorising about sustainability science can be used to cast light on contested natural resource management issues, in this case mining in northern Sweden. By exposing the range of alternative Pathways to critical norms of sustainable development, we ascertain whether action alternatives are compatible with sustainable futures. The framework provides a way in which sustainability science can better understand the origins of natural resource management conflicts, characterise the positions of the actors involved, identify the potential for cooperation between stakeholders leading to policy resolution and judge what Pathways help or hinder the pursuit of sustainable development. In addition, it can enhance sustainability science by guiding integrative sustainability research at the project scale. 相似文献
198.
Gabi Drochioiu Karin Popa Doina Humelnicu Manuela Murariu Ion Sandu Alexandru Cecal 《毒物与环境化学》2013,95(2):221-235
A simple approach was carried out to study the effects of various parameters on high performance liquid chromatography (HPLC) performance of microcystin-LR (MC-LR) analysis in samples from some reservoirs and rivers in Taiwan under simulation conditions. Nature of column and its packing affected the instrument sensitivity. Varied column length indicated the longer column enhanced (C18, 5 μm, 4.6 × 150 mm) HPLC performance. Studies on mobile phase found that ratio and concentration of the mobile phase gradient greatly influenced the peak shape, retention time, and optimal conditions of mobile phase were set at acetonitrile and 0.01M ammonium acetate (30:70). Different compounds were added to mobile phase and their contribution to HPLC spectra was reported. Detection limits were carefully measured and reported. These investigations provide simple and important information that may be applied to HPLC performance for microcystin analysis from natural water systems. 相似文献
199.
Trijntje van der Velde-Koerts Nicolas Breysse Lauriane Pattingre Paul Y. Hamey Jason Lutze Karin Mahieu 《Journal of environmental science and health. Part. B》2018,53(6):380-393
ABSTRACTIn 2015 a scientific workshop was held in Geneva, where updating the International Estimate of Short-Term Intake (IESTI) equations was suggested. This paper studies the effects of the proposed changes in residue inputs, large portions, variability factors and unit weights on the overall short-term dietary exposure estimate. Depending on the IESTI case equation, a median increase in estimated overall exposure by a factor of 1.0-6.8 was observed when the current IESTI equations are replaced by the proposed IESTI equations. The highest increase in the estimated exposure arises from the replacement of the median residue (STMR) by the maximum residue limit (MRL) for bulked and blended commodities (case 3 equations). The change in large portion parameter does not have a significant impact on the estimated exposure. The use of large portions derived from the general population covering all age groups and bodyweights should be avoided when large portions are not expressed on an individual bodyweight basis. Replacement of the highest residue (HR) by the MRL and removal of the unit weight each increase the estimated exposure for small-, medium- and large-sized commodities (case 1, case 2a or case 2b equations). However, within the EU framework lowering of the variability factor from 7 or 5 to 3 counterbalances the effect of changes in other parameters, resulting in an estimated overall exposure change for the EU situation of a factor of 0.87-1.7 and 0.6-1.4 for IESTI case 2a and case 2b equations, respectively. 相似文献
200.
Vulturius Gregor André Karin Swartling Åsa Gerger Brown Calum Rounsevell Mark D. A. Jönsson Anna Maria Blanco Victor 《Regional Environmental Change》2018,18(5):1571-1571
Regional Environmental Change - The published online version contains mistake. Anna Maria Jönsson was inadvertently omitted in the author group section. Correct author group section is shown... 相似文献