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61.
The operational sex ratio (OSR) may influence the intensity of competition for mates and mate choice and is therefore thought
to be a major factor predicting the intensity and direction of sexual selection. We studied the opportunity for sexual selection,
i.e., the variance in male reproductive success and the direction and intensity of sexual selection on male body mass in bank
vole (Clethrionomys glareolus) enclosure populations with experimentally manipulated sex ratios. The opportunity for sexual selection was high among male-biased
OSRs and decreased towards female-biased OSRs. Paradoxically, selection for large male body mass was strongest in female-biased
OSRs and also considerable at intermediate OSRs, whereas at male-biased OSRs, only a weak relationship between male size and
reproductive success was found. Litters in male-biased OSRs were more likely to be sired by multiple males than litters in
female-biased OSRs. Our results suggest that the intensity and direction of sexual selection in males differs among different
OSRs. Although the direction of sexual selection on male body mass was opposite than predicted, large body mass can be favored
by sexual selection. Naturally varying OSRs may therefore contribute to maintain variation in male sexually selected traits. 相似文献
62.
Olli Dahl Risto Pöykiö Hannu Nurmesniemi 《Journal of Material Cycles and Waste Management》2008,10(1):87-92
In Finland, the new limit values for heavy metals in fertilizers used in agriculture and in forestry came into force in March
2007, and for materials used as earth construction agents, in June 2006. From the utilization point of view, it was notable
that the total heavy metal concentrations (Cd, Cu, Pb, Cr, Mo, Zn, As, Ni, Ba, and Hg) in fly ash from a coal-fired power
plant were lower than those limit values. The concentrations of the easily soluble elements Ca, Mg, Na, P, and Zn in the fly
ash were between 3.5 and 35 times higher than those found in the coarse mineral soils of Finland. Fly ash is a potential agent
for soil remediation and for improving soil fertility. If inorganic materials and by-products are utilized in earthworks,
the content of harmful compounds must be low and the harmful components must be tightly bound to the matrix. Therefore, a
five-stage sequential extraction procedure was used to evaluate the extractability of different elements in fly ash into the
following fractions: (1) the water-soluble fraction, (2) the exchangeable fraction (CH3COOH), (3) the easily reduced fraction (NH2OH-HCl), (4) the oxidizable fraction (H2O2 + CH3COONH4), and (5) the residual fraction (HF + HNO3 + HCl). 相似文献
63.
Holmberg Maria Mulder Jan Posch Maximilian Starr Michael Forsius Martin Johansson Matti Bak Jesper Ilvesniemi Hannu Sverdrup Harald 《Water, Air, & Soil Pollution: Focus》2001,1(1-2):91-101
We reviewed the current methods for calculatingcritical loads of acidity for forest soils. The consequencesof four sets of assumptions concerning the soil modelstructure, parameter values and the critical loads criterionwere explored by comparing the values of the averageaccumulated exceedance (AAE) calculated for Finland withdeposition values for the year 1995. The AAE index is given inthe unit of deposition and is a measure of how far a region isfrom being protected in terms of fulfilling a certaincriterion, taking into account the size of the ecosystem areas.Using a critical limit for the molar ratio of theconcentrations of base cations to aluminium in soil solutiongave the lowest average accumulated exceedance. Assumingorgano-aluminium complexes and leaching of organic anions gaveAAE = 4 eq ha-1 a-1, which was close to the valueobtained with the standard approach used in Finland, assuminggibbsite equilibrium and no leaching of organic anions,yielding AAE = 5 eq ha-1 a-1. With a critical basesaturation limit, instead of the concentrations criterion, theAAE index was 17 eq ha-1 a-1. The highest averageaccumulated exceedance (AAE = 25 eq ha-1 a-1),corresponding to the lowest critical load, was obtained whenthe effects-based criterion (critical concentration or criticalbase saturation) was substituted with one restricting thedeterioration of the neutralizing capacity of the soil, ANC
le(crit) = 0. These tests illustrate the variabilityof the critical load values for acidity that can be introducedby changing the criterion or by varying the calculation method,without, however, representing the extreme values of criticalloads that could be derived. 相似文献
64.
Alkaline phosphatase (ALP) activity was determined in 255 amniotic fluid samples collected by amniocentesis between 15 and 39 weeks of gestation. The samples were originally used for chromosomal analysis and/or alpha-fetoprotein measurements. The mean ALP activity in early amniotic fluid from pregnancies with fetal trisomy 18 and 21 syndromes was half of that found in the controls. Highly elevated ALP activity (over 10 times the median level) was found in 14 samples. Two of these pregnancies had normal outcome. Three samples were from pregnancies with intrauterine fetal death. Fetal disorders, including abdominal wall defect (four cases), Meckel's syndrome (two), hydrops fetalis syndrome (two) and genital anomaly (one), were observed in nine cases. Moderately elevated ALP activity (over three times the median) was found in 10 cases, including five pregnancies with a preterm labour shortly after the sample collection. The results indicate that elevated ALP activity in the third trimester amniotic fluid is often associated with fetal disorders. 相似文献
65.
Vancomycin-resistant enterococci (VRE) and methicillin-resistant staphylococci, most notably methicillin-resistant Staphylococcus aureus (MRSA), are serious clinical problems. The antibiotic arsenal available against them is limited, and new mutants worsen the
situation. We studied the activity of (+)-usnic acid, an old lichen-derived drug, and its sodium salt against clinical isolates
of VRE and MRSA using the agar diffusion and minimal inhibitory concentration (MIC) methods. The acid and, especially, the
sodium salt had potent antimicrobial activity against all clinical isolates of VRE and MRSA studied. The MIC values of the
sodium salt against VRE strains ranged between 4 and 16 μg/ml (1-day test) and between 4 and 31 μg/ml (2-day test), being
below 8 μg/ml for most strains. The salt had potent activity even against those strains that were not inhibited by ampicillin
(125 μg/ml), and it never lost its activity after 24 h, in contrast to ampicillin. Thus, in spite of the fact that usnic acid
can in some cases cause serious toxicity, it and its salts may be worth considering in clinical practice in cases where other
therapies have failed or the microbe is resistant toward other agents. 相似文献