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71.
Polychlorinated dibenzothiophenes (PCDTs) could be classified as persistent organic pollutants (POPs) in the environment and are particularly interesting due to their structural resemblance to highly toxic dioxins. We show here some basic environmental properties such as n-octanol water (KOW), n-octanol/air (KOA) and air/water (KAW) partition coefficients as well as Henry’s law constants (KH) for all 135 congeners of chlorodibenzothiophene. Predictions were made by regression of principal components (PCR) and with aid of a set of standard chemicals, for which physical–chemical properties are well featured. Computed KOW, KOA, KAW and KH values for mono-CDTs ranged, respectively, between 4.66 and 4.71, 7.48 and 7.55, −2.84 and −2.82, 3.56 and 3.74; for di-CDTs between 5.02 and 5.28, 8.03 and 8.29, −3.01 and −2.95, 2.42 and 2.75; for tri-CDTs between 5.53 and 5.70, 8.65 and 8.87, −3.2 and −3.11, 1.58 and 1.92; for tetra-CDTs between 5.95 and 6.13, 9.27 and 9.50, −3.39 and −3.27, 1.02 and 1.33; for penta-CDTs between 6.38 and 6.51, 9.88 and 10.05, −3.54 and −3.45, 0.72 and 0.88; for hexa-CDTs between 6.83 and 6.97, 10.54 and 10.66, −3.72 and −3.64, 0.47 and 0.56; for hepta-CDTs between 7.28 and 7.35, 11.12 and 11.20, −3.81 and −3.87, 0.33 and 0.38; for octa-CDT 7.74, 11.78, −4.04 and 0.23. An estimated value of the three types of partition coefficient and Henry’s law constants suggest that polychlorinated dibenzothiophenes are lipophilic and semi-volatile persistent organic pollutants. Their mobility in the environment seems to be very similar to that of some well-known POPs such as polychlorinated dibenzofurans, -dibenzo-p-dioxins, and -biphenyls or organochlorine pesticides.  相似文献   
72.
The aim of this study was to assess handgrip and 5 other types of force in 52 women and to determine if handgrip force reflected general upper limb force capabilities correlated with age. The women were divided into subgroups according to age: 20-25, 45-50 and 55-65 years. Maximum forces of the right upper limb were measured in 6 types of force activities. In most tests the values of force showed statistically significant differences between the 20-25 group and the groups aged 45-50 and 55-64 years. The results did not show any differences related to age or to force activities that involved the small muscles of the forearms and hands. Thus handgrip force cannot always be considered an indicator of total force capabilities.  相似文献   
73.
The aim of the study was to investigate the possibility of using infrared (IR) thermography for assessing muscle fatigue during low effort. Three tests at constant levels of load 5, 15 and 30% of maximum voluntary contraction (MVC) lasting 5 min each were performed on a group of 10 men. Temperature and electromyographic (EMG) signal were registered from biceps brachii (BB). Analysis focused on the influence of load on the values and changes in time of muscle temperature. Correlations between temperature and EMG parameters (RMS, MPF and MF) were also analysed. Constant load sustained during the tests resulted in an increase in the temperature of BB. There were statistically significant correlations between temperature and EMG parameters for most subjects. Results of the study suggest that IR thermography can be an alternative or supplementary method for assessing muscle fatigue at low levels of contraction.  相似文献   
74.
Rapid and nondestructive methods such as diffuse reflectance infrared spectroscopy provide potentially useful alternatives to time-consuming chemical methods of soil metal analysis. To assess the utility of near-infrared reflectance spectroscopy (NIRS) and diffuse mid-infrared reflectance spectroscopy (DRIFTS) for soil metal determination, 70 soil samples from the metal mining region of Tarnowskie Gory (Upper Silesia, Poland) were analyzed by both chemical and spectroscopic methods. Soils represented a wide range of pH (4.0-8.0), total carbon (5.1-73.2 g kg(-1)), and textural classes (from sand to silty clay loam). Soils had various contents of metals (14-4500 mg kg(-1) for Zn, 18-6530 mg kg(-1) for Pb, and 0.17-34 mg kg(-1) for Cd), ranging from natural background levels to high contents indicative of industrial contamination in the region. Soil samples were scanned at the wavelengths from 400 to 2498 nm (near-infrared region) and from 2500 to 25000 nm (mid-infrared region). Calibrations were developed using the one-out validation procedure under partial least squares (PLS) regression. Mid-infrared spectroscopy markedly outperformed NIRS. Iron, Cd, Cu, Ni, and Zn were successfully predicted using DRIFTS. The coefficients of determination (R(2)) between actual and predicted contents were 0.97, 0.94, 0.80, 0.99, and 0.96 for those metals, respectively. Only Pb content was predicted poorly. Calibrations using NIRS were less accurate. Root mean squared deviation (RMSD) values were from 1.27 (Pb) to 3.3 (Ni) times higher for NIRS than for DRIFTS. Results indicate that DRIFTS may be useful for accurate predictions of metals if samples originate from one region.  相似文献   
75.
Bioavailability of Pb in contaminated soils can be highly decreased by conversion of labile Pb species into pyromorphite Pb5(PO4)3Cl, induced by amendment with a phosphate source. However, PO4 3− can be specifically adsorbed on goethite α-Fe(OH)3 present in soils. We demonstrate that despite the stability of phosphate ions adsorbed on goethite surface, the reaction between goethite-adsorbed phosphates and aqueous lead in the presence of Cl results in crystallization of pyromorphite. Two morphological forms of pyromorphite formed on goethite were observed: 1) incrustations, indicating direct reaction of Pb and Cl ions with PO4 3− adsorbed on goethite surface, and 2) aggregates of pyromorphite crystals indicating that the reaction with PO4 3− ions took place in the volume of the solution. This suggests that precipitation of pyromorphite is faster than desorption of phosphates and that aqueous Pb may serve as a sink for phosphate ions by shifting the equilibrium and inducing PO4 3− desorption.  相似文献   
76.
Although shell colour polymorphism of the land snail Cepaea nemoralis is a well-known phenomenon, proximate and ultimate factors driving its evolution remain uncertain. Polymorphic species show variation in behavioural responses to selective forces. Therefore, we estimated effects of various environmental factors (temperature, humidity, food availability, (micro)habitat structure and predatory pressure) on behavioural response (frequency of locomotion, climbing and hiding) of C. nemoralis morphs, in experimental and natural conditions. In the experimental part of study, the frequency of locomotion was negatively affected by temperature and the presence of food and positively influenced by the presence of light. Morphs significantly differed in behavioural responses to environmental variability. Pink mid-banded and yellow five-banded morphs climbed less often and hide in shelter more often than yellow and pink unbanded individuals when temperature was low and food was absent. Snails fed most often at moderate temperature compared to low and high temperatures. Field investigations partially confirmed differences among morphs in frequency of climbing, but not in terms of probability of hiding in sheltered sites. In natural colonies, temperature and (micro)habitat structure significantly affected frequency of climbing as well as hiding in shelter. Snails more often hid in sheltered sites where thrushes preyed on Cepaea. Tendency of unbanded morphs to climb trees may have evolved under avian predatory pressure as thrushes forage on a ground. Tendency of banded morphs to hide in sheltered sites may reflect prey preferences for cryptic background. The results implicate that differential behaviour of C. nemoralis morphs compensate for their morphological and physiological limitations of adaptation to habitat.  相似文献   
77.
The aim of this work is to investigate the application of fly ash adsorbent for removal of arsenite ions from dilute solution (100–1,000 ppm). Experiments were carried out using material from the “Turów” (Poland) brown-coal-burning power plant, which was wetted, then mixed and tumbled in a granulator to form spherical agglomerates. Measurements of arsenic adsorption from aqueous solution were carried out at room temperature and natural pH of fly ash agglomerates, in either a shaken flask or circulating column, to compare two different methods of contacting solution with adsorbent. Adsorption isotherms of arsenic were determined for agglomerated material using the Freundlich equation. Kinetic studies indicated that sorption follows a pseudo-second-order model. Preferable method to carry out the process is continuous circulation of arsenite solution through a column.  相似文献   
78.
Aim of the present study was an attempt to find a correlation between physicochemical structure of veterinary drugs and the maximum residue limit (MRL) for muscle tissue of food producing animals. Direct correlation and analysis in quintile groups for 52 physicochemical parameters were performed. An internal validation using leave-one-out cross-validation was performed. In the quintile groups, there were 11 arithmetic expressions created for the limited group of individual parameters (13 from 52 analyzed), which showed a significant linear or quadratic correlation between the number of quintile group and the mean value of MRL within the quintile. The results obtained suggest that there is no direct correlation between individual physicochemical parameters and MRL value in muscle tissue; however, such correlation can be determined for arithmetic expressions created on the basis of several physicochemical parameters, using quintile group analysis.  相似文献   
79.
80.
The paper presents results of screening analysis of all Polish national parks (23) contamination with Cd, Cu, Pb and Zn on the basis of a three-level characteristic of heavy metal presence in Norway spruce stands: accumulation on the needle surface, concentration of heavy metals in spruce needles and concentration of bioavailable heavy metals in the soil. Based on the obtained results, the classification of forest ecosystem hazard in national parks with heavy metals was made using synthetic indicators. It was found out that Babiogórski, Magurski, Ojcowski and Gorczański National Parks, located in the southern part of the country, were the most polluted with heavy metals. It is probably due to a higher industrial activity in this part of Poland and the transboundary transport of air pollutants. A little lower level of pollution was observed in Kampinoski National Park located in the middle of the country. The concentration of heavy metals found in needles from national parks does not seem to be harmful for the health status of the trees. Statistically significant correlation between all parameters, which was found for cadmium--the most mobile of the analysed elements--shows that this metal can be proposed as a marker to reflect present effect of industrial emission on forests.  相似文献   
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