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41.
A case of multiple intestinal atresia is described. Dilatation of the bowel was observed at 17 weeks' gestation during routine ultrasound scan of a healthy Caucasian primigravida from a non-consanguineous marriage. Amniocentesis was performed. The karyotype was normal male and cystic fibrosis screening was negative. Regular scans were performed throughout the pregnancy and a simple bowel obstruction was suspected. The baby was delivered at 37 weeks' gestation in good condition. Initial clinical examination was normal but abdominal distension developed during the first day. At laparotomy, prepyloric septal atresia, a distal duodenal membrane, and multiple intestinal atresia were found. The baby died aged 4 days. Post-mortem examination of the abdomen confirmed the absence of lumen from long segments of the small intestine together with areas of colonic atresia. Histology and distribution were consistent with those reported in familial multiple intestinal atresia. The pitfalls in the interpretation of prenatal ultrasound scans and the possibility of prenatal diagnosis in future pregnancies are discussed. 相似文献
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43.
Robert A. Boyd 《Journal of the American Water Resources Association》1998,34(3):507-518
ABSTRACT: Cedar Rapids obtains its municipal water supply from a shallow alluvial aquifer along the Cedar River in east-central Iowa. Water samples were collected and analyzed for selected isotopes and chlorofluorocarbons to characterize the ground-water flow system near the municipal well fields. Analyses of deuterium and oxygen-18 indicate that water in the alluvial aquifer and in the underlying carbonate bedrock aquifer was recharged from precipitation during modern climatic conditions. Analyses of tritium indicate modern, post-1952, water in the alluvial aquifer and older, pre-1952, water in the bedrock aquifer. Mixing of the modern and older waters occurs in areas where (1) the confining layer between the two aquifers is discontinuous, (2) the bedrock aquifer is fractured, or (3) pumping of supply wells induces the flow of water between aquifers. Analyses of chlorofluorocarbons were used to determine the date of recharge of water samples. Water in the bedrock aquifer likely was recharged prior to the 1950s. Water in the alluvial aquifer likely was recharged from the 1960s to 1990s. Biodegradation or sorption probably affected some of the ground water analyzed for chlorofluorocarbons. These processes reduce the concentrations of CFCs, which results in older than actual calculated dates of recharge. 相似文献
44.
Coral reefs are highly dynamic and productive marine ecosystems, providing habitat and refuge for an enormous number of species
including fish, invertebrates and algae. With increased anthropogenic pressures and global climate change, many coral reefs
are rapidly declining. Currently, there is limited knowledge on condition and community assemblage composition of shallow
fringing coral reefs along the south-eastern coast of Queensland, Australia. With increased demand to determine existence
of coastal fringing reefs by National Regional Management groups, a rapid cost effective method to determine reef composition
and condition was required. The aim of this study was to determine the benthic structure and extent of two small coastal fringing
reefs (Hummock Hill Reef and Stringers Reef) along the Southern Great Barrier Reef. Reef substrate assessments were carried
out using a rapid assessment technique and a Point Intercept Method (PIM). The data were analysed and classified using a Geographic
Information System (GIS). Percent substrate cover was calculated using a visual basic image analysis program. The Point intercept
method showed higher accuracy over the rapid assessment technique (up to 15–40% difference) and was thus deemed a more suitable
classification tool for reefs with high structural complexity and heterogeneity. This study focused on piloting a rapid, cost
effective Point Intercept Technique using random point count methodology to document coral benthic habitat and extent over
a commonly used rapid assessment method as a tool for reef coastal management and conservation. The two techniques were compared
and substrate classification success, limitations and errors were discussed. 相似文献
45.
A test of elemental defence against slugs by Ni in hyperaccumulator and non-hyperaccumulator Streptanthus species 总被引:2,自引:0,他引:2
Summary. Tissues of most plant species contain < 10 μg Ni g−1 but Ni hyperaccumulators contain more than 1000 μg Ni g−1 . Hyperaccumulated Ni can defend plants from some herbivores but the defensive role of lesser Ni concentrations is little explored. We raised five species of Streptanthus (Brassicaceae) native to ultramafic soils, one of which (S. polygaloides) is a Ni hyperaccumulator whereas the others are simply Ni-tolerant, on Ni-amended and unamended green-house soils to create plants differing in Ni concentrations. On high-Ni soil, leaves of the hyperaccumulator contained 3800 μg Ni g−1 whereas leaves of non-hyperaccumulator species contained 41–64 μg Ni g−1. Plants of all species grown on low-Ni soils had < 14 μg Ni g−1. Slugs (Limax maximus) were fed plant material in no-choice tests over a 50-day period and survival and mass changes were recorded. All slugs fed high-Ni leaves of the hyperaccumulator species died within 21 d. Slugs fed high-Ni leaves of the other species did not differ significantly in survival or mass change from those fed low-Ni leaves. In choice tests, slugs (Lehmannia valentiana) offered both high- and low-Ni S. polygaloides leaves did little damage to high-Ni leaves. We conclude that hyperacumulated Ni can defend S. polygaloides from slug herbivory via both toxicity and deterrence, but these defensive effects do not extend to Streptanthus species containing < 70 μg Ni g−1. 相似文献
46.
Pohlman JW Coffin RB Mitchell CS Montgomery MT Spargo BJ Steele JK Boyd TJ 《Environmental monitoring and assessment》2002,75(2):155-167
Polycylic aromatic hydrocarbons (PAHs) are commoncontaminants in industrial watersheds. Their origin,transport and fate are important to scientists,environmental managers and citizens. The Philadelphia NavalReserve Basin (RB) is a small semi-enclosed embayment nearthe confluence of the Schuylkill and Delaware Rivers inPennsylvania (USA). We conducted a study at this site todetermine the tidal flux of particles and particle-boundcontaminants associated with the RB. Particle traps wereplaced at the mouth and inside the RB and in the Schuylkilland Delaware Rivers. There was net particle deposition intothe RB, which was determined for three seasons. Spring andfall depositions were highest (1740 and 1230 kg ofparticles, respectively) while winter deposition wasinsignificant. PAH concentrations on settling particlesindicated a net deposition of 12.7 g PAH in fall and 2.1 gPAH in spring over one tidal cycle. There was nosignificant PAH deposition in the winter. Biodegradationrates, calculated from 14C-labeled PAH substratemineralization, could attenuate only about 0.25% of the PAHdeposited during a tidal cycle in fall. However, in thespring, biodegradation could be responsible for degrading50% of the settling PAHs. The RB appears to be a sink forPAHs in this watershed. 相似文献
47.
Amanda D. Boyd 《Environmental Communication: A Journal of Nature and Culture》2017,11(2):184-204
An increasing demand for the development and implementation of low carbon energy systems has furthered the need to understand the factors that influence a community's support for or opposition to local energy developments. Carbon dioxide capture and geological storage (CCS) is one such energy system where it is widely acknowledged that public perceptions and acceptance of CCS technologies are critical to their implementation. CCS refers to the capture of carbon dioxide emissions from industrial sources and the long-term storage of these emissions in stable underground reservoirs. This case study examines how place attachment and community networks factored into resident's perceptions of a proposed CCS project that was ultimately canceled due to local opposition. Participants were concerned about preserving shared places, spaces, and interactions that were valued by community members. Results demonstrate the need to ascertain how locally affected populations view CCS or other energy developments, especially with regard to their ideas about community, sense of place (ties to area and local relationships), and how they communicate about those factors. Such factors are important given the initiative to develop low carbon energy systems in rural areas. 相似文献
48.
49.
Seasonally breeding predators, which are limited in the time available for provisioning young at a central location, and
by the fasting abilities of the young, are likely to maximize energy delivery to the young by maximizing the rate of energy
delivery averaged over the whole period of investment. Reduction in food availability or increased foraging costs will alter
the optimal behavior of individuals. This study examined the behavioral adaptations of a diving predator, the Antarctic fur
seal, to increased foraging costs during lactation. One group of mothers (n=5, treatment) was fitted with additional drag to increase the cost of transport in comparison with a control group (n=8). At the scales of the individual dives, the treatment group made more shorter, shallower (< 30 m) dives. Compensation for
slower swimming speeds was achieved by diving at a steeper angle. Overall, diving behavior conformed to several specific theoretical
predictions but there were also departures from theory, particularly concerning swimming speed during diving. Diving behavior
appears to be adjusted to maximize the proportion of time spent at the bottom of dives. At the scale of diving bouts, no difference
was observed between the treatment and control groups in terms of the frequency and duration of bouts and there was also no
difference between the two groups in terms of the proportion of time spent diving. At the scale of complete foraging cycles,
time taken to return to the pup was significantly longer in the treatment group but there was no difference in the rate of
delivery of energy (measured from pup growth rate) to the pups in each group. Since mothers in the treatment group did not
use significantly more body reserves, we conclude that behavioral adjustments at the scale of individual dives allowed mothers
in the treatment group to compensate for the additional foraging costs. Pup growth rate appears to be less sensitive to the
foraging conditions experienced by mothers than foraging trip duration.
Received: 14 June 1996 / Accepted after revision: 16 November 1996 相似文献
50.