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81.
K. C. Batista D. A. K. Silva L. A. F. Coelho S. H. Pezzin A. P. T. Pezzin 《Journal of Polymers and the Environment》2010,18(3):346-354
There is great interest in developing eco-friendly green biocomposites from plant-derived natural fibers and crop-derived
bioplastics attributable to their renewable resource-based origin and biodegradable nature. Fully biodegradable composites,
made from both biodegradable polymeric matrices and natural fibers, should be advantageous in some applications, such as one
way packaging. Polyhydroxyalkanoates (PHAs) are naturally occurring biodegradable polymers produced from a wide range of microorganisms,
with poly(3-hydroxybutyrate) P(3HB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) being important examples of PHAs. In this work, biocomposites of PHBV consisting of a PHBV matrix
incorporating peach palm particles (PPp), [i.e., 100/0, 90/10, 80/20 and 75/25 (%w/w) PHBV/PPp] were processed by injection
molding at 160 °C. The effect of PPp loading on the thermal and the mechanical properties, as well as on the morphological
behavior of the PHBV/PPp biocomposites was investigated. Soil biodegradation tests were carried out by burying specimen beakers
containing aged soil and kept under controlled temperature and humidity in accordance with ASTM G160-98. Degradation of the
biocomposites was evaluated by visual analysis, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) following
test exposures of up to 5 months. The addition of PPp reduced the maximum strength and the elongation at break of the biocomposites.
On the other hand, the Young’s modulus improved with the PPp content. Micrographs of the fracture surfaces following tensile
strength testing revealed a large distance between the PHBV matrix and PPp particles although a low interaction is expected.
Where measured, these distances tended increase as the PPp content of the biocomposites increased. Soil biodegradation tests
indicated that the biocomposites degraded faster than the neat polymer due to the presence of cavities that resulted from
introduction of the PPp and that degradation increased with increasing PPp content. These voids allowed for enhanced water
adsorption and greater internal access to the soil-borne degrader microorganisms. 相似文献
82.
Cheese, Tourists, and Red Pandas in the Nepal Himalayas 总被引:3,自引:0,他引:3
83.
84.
We assessed relationships between the extent to which farmers reported exposure to relevant information and their attitudes
towards, knowledge about, and degree of adoption of riparian management strategies. We also examined associations between
knowledge of, or receipt of, financial assistance for riparian fencing/planting and intentions for and extent of adoption
of this strategy. A mail survey of 718 pastoral farmers in Otago and Southland in New Zealand [294 surveys returned (41%)]
yielded 279 usable questionnaires. Indices were developed to reflect range and frequency of information use and range of practices
adopted. Attitudes were measured using Likert-type responses to 11 statements, and knowledge as a score on a ten-question
true/false test. Positive relationships between information and the three main response variables (attitude, knowledge, and
adoption) were weak but significant and systematic. These associations remained significant when important demographic and
farm characteristics were taken into account. Informed farmers were more likely to report intentions to carry out riparian
fencing or planting within the next year. Farmers who were aware that funding was available were also more likely to state
this intention, independent of information level. The reported extent to which waterways had been fenced to exclude stock
was related to receipt of funding, but not to information level. Financial factors were the most influential barrier preventing
adoption of permanent fencing. Our research shows a positive correlation between the receipt of information and funding and
the adoption of specific riparian management measures. 相似文献
85.
Paranhos Gazineu MH de Araújo AA Brandão YB Hazin CA de O Godoy JM 《Journal of environmental radioactivity》2005,81(1):47-54
Scales and sludge generated during oil extraction and production can contain uranium, thorium, radium and other natural radionuclides, which can cause exposure of maintenance personnel. This work shows how the oil content can influence the results of measurements of radionuclide concentration in scale and sludge. Samples were taken from a PETROBRAS unit in Northeast Brazil. They were collected directly from the inner surface of water pipes or from barrels stored in the waste storage area of the E&P unit. The oil was separated from the solids with a Soxhlet extractor by using aguarras at 90+/-5 degrees C as solvent. Concentrations of 226Ra and 228Ra in the samples were determined before and after oil extraction by using an HPGe gamma spectrometric system. The results showed an increase in the radionuclide concentration in the solid (dry) phase, indicating that the above radionuclides concentrate mostly in the solid material. 相似文献
86.
The high degree of physical disturbance associated with conventional response options to oil spills in wetlands is driving
the investigation of alternative cleanup methodologies. In March 1995, a spill of gas condensate in a brackish marsh at Rockefeller
Wildlife Refuge in southwestern Louisiana was remediated through the use of in situ burning. An assessment of vegetation recovery
was initiated in three treatment marshes: (1) oil-impacted and burned, (2) oil impacted and unburned, and (3) a nonoiled unburned
reference. We compared percent cover, stem density, and biomass in the treatment marshes to define ecological recovery of
the marsh vegetation and soil hydrocarbon content to determine the efficacy of in situ burning as a cleanup technique. Burning
led to a rapid decrease in soil hydrocarbon concentrations in the impacted-and-burned marsh to background levels by the end
of the first growing season. Although a management fire accidentally burned the oil-impacted-and-unburned and reference marshes
in December 1995, stem density, live biomass, and total percent cover values in the oil-impacted-and-burned marsh were equivalent
to those in the other treatment marshes after three years. In addition, plant community composition within the oil-impacted-and-burned
marsh was similar to the codominant mix of the grasses Distichlis spicata (salt grass) and Spartina patens (wire grass) characteristic of the surrounding marsh after the same time period. Rapid recovery of the oil-impacted-and-unburned
marsh was likely due to lower initial hydrocarbon exposure. Water levels inundating the soil surface of this grass-dominated
marsh and the timing of the in situ burn early in the growing season were important factors contributing to the rapid recovery
of this wetland. The results of this in situ burn evaluation support the conclusion that burning, under the proper conditions,
can be relied upon as an effective cleanup response to hydrocarbon spills in herbaceous wetlands. 相似文献
87.
Dr William Cusick Michael Bork Betsy Fabri Peter Benn John F. Rodis Louis Buttino JR 《黑龙江环境通报》1995,15(11):1078-1081
A 27-year-old gravida 4, para 3 was found to have anhydramnios at 14 weeks' gestation following a size/date discrepancy noted at her routine prenatal visit. A detailed ultrasound revealed multiple fetal anomalies including congenital heart defect, chest hypoplasia, and bilateral dysplastic kidneys. Karyotype revealed trisomy 16 in 15/15 cells from a tissue specimen obtained from the fetal cord insertion site following elective pregnancy termination. 相似文献
88.
89.
The most promising technologies to remove perchlorate from water are ion exchange and biological reduction. Although successful, ion exchange only separates perchlorate from water; it does not eliminate it from the environment. The waste streams from these systems contain the caustic or saline regenerant solutions used in the process as well as high levels of perchlorate. Biological reduction could be used to treat the regenerant waste solutions from the ion exchange process. A treatment scheme, combining ion exchange and biodegradation, is proposed to completely remove perchlorate from the environment. Perchlorate-laden resins generate brines containing salt concentrations up to 6% or caustic solutions containing up to 0.5% ammonium. Both, high salt and ammonium hydroxide concentrations are potentially toxic to microorganisms. Therefore, the challenge of the proposed system is to find perchlorate reducing microorganisms that are effective under such stressful conditions. Preliminary results have shown that salt concentrations as low as 0.5% reduced the perchlorate biodegradation rate by 30%; salt concentrations greater than 1% decreased this rate to 40%. Although biodegradation was seen in ammonium levels of 0.4%, 0.6% and 1%, the perchlorate biodegradation rate was 90% of that at 0% ammonium hydroxide. Further research will focus on the isolation and/or acclimation of microorganisms that are able to biodegrade perchlorate under these stressful conditions. 相似文献
90.
PHILIP C. STOUFFER† RICHARD O. BIERREGAARD JR ‡. CHERYL STRONG§ THOMAS E. LOVEJOY†† 《Conservation biology》2006,20(4):1212-1223
Abstract: The rainforests of the Amazon basin are being cut by humans at a rate >20,000 km2 /year, leading to smaller and more isolated patches of forest, with remaining fragments often in the range of 1–100 ha. We analyzed samples of understory birds collected over 20 years from a standardized mist-netting program in 1– to 100-ha rainforest fragments in a dynamic Amazonian landscape near Manaus, Brazil. Across bird guilds, the condition of second growth immediately surrounding fragments was often as important as fragment size or local forest cover in explaining variation in abundance. Some fragments surrounded by 100 m of open pasture showed reductions in insectivorous bird abundance of over 95%, even in landscapes dominated by continuous forest and old second growth. These extreme reductions may be typical throughout Amazonia in small (≤10 ha), isolated fragments of rainforest. Abundance for some guilds returned to preisolation levels in 10- and 100-ha fragments connected to continuous forest by 20-year-old second growth. Our results show that the consequences of Amazonian forest loss cannot be accurately described without explicit consideration of vegetation dynamics in matrix habitat. Any dichotomous classification of the landscape into "forest" and "nonforest" misses essential information about the matrix. 相似文献