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51.
    
Ohne Zusammenfassung  相似文献   
52.
53.
Goal, Scope and Background  Situated in the transboundary belt between Montenegro and Albania, Lake Skadar is the largest freshwater reservoir in Southeastern Europe. Because of the wide range of endemic, rare or endangered plant and animal species it supports, Lake Skadar and its extensive adjacent wetlands are internationally recognised as a site of significance and importance (Ramsar site). Within the last 10 to 20 years, Lake Skadar was exposed to intensive pollution. For the assessment of the ecotoxic load of the sediments sampled in Lake Skadar, a triad approach was recently applied. Overall, a complex spectrum of ecotoxic loads was elucidated. The aim of the present study was to use plant-based bioassays for assessing the sediment quality of Lake Skadar in order to facilitate and complement the triad test battery. The newly developed sediment contact test with Myriophyllum aquaticum and the aquatic growth inhibition test with Lemna minor were applied to native sediments and pore water, respectively, allowing the investigation of different toxicity-effects caused by particle-bound pollutants as well as pollutants in the interstitial water. This investigation is the first application of the novel sediment contact test with Myriophyllum aquaticum to lake sediments. Methods  Sediment samples were taken from nine selected sites at Lake Skadar and investigated by the sediment contact assay with Myriophyllum aquaticum. The pore water was extracted from these sediment samples to be analysed in the aquatic growth inhibition test with Lemna minor. The results of the sediment contact tests were compared with each other and with those of the aquatic growth inhibition test. Results and Discussion  Both applied macrophyte biotests revealed distinct changes in the growth behaviour of the two macrophytes subsequent to the exposure to the investigated natural sediments of Lake Skadar. The Myriophyllum sediment contact test revealed significant toxicity in the sediment samples from Radus and Kamenik, whereas the aquatic Lemna test showed inhibition effects for the samples from Sterbeq, Plavnica and Kamice. Data obtained with the newly developed Danio rerio contact test and the Arthrobacter globiformis contact test confirmed the Myriophyllum results. Analyses of the heavy metal content in the sediments revealed low or moderate contamination levels. Correlation analyses between the content of heavy metals in the sediments and growth inhibition of Myriophyllum aquaticum showed a significant correlation between Cr concentrations and growth inhibition. Comparable findings are available for a German river system. In contrast, no significant correlation between inhibition rates and concentration of metals could be observed with Lemna minor. Conclusions  It was shown that the newly developed sediment contact test with Myriophyllum aquaticum is applicable to lake sediments. In both the sediment contact test with Myriophyllum aquaticum on whole sediments and the aquatic growth inhibition test with Lemna minor on pore water, plant growth was influenced by the natural sediments and its components. Therefore, both test systems were found to be suitable for the detection of phytotoxic effects upon exposure to sediments. Myriophyllum aquaticum as test organism of the contact test grows directly in the sediment without an additional water-layer. Thus, it is able to detect toxicity caused by particle-bound phytotoxic substances as well as pore water-related contamination, while the floating Lemna minor can only detect effects emanating from pore water. Significant differences of the results were observed between these two test systems and, accordingly, the two different exposure scenarios. Hence, none of the tests can replace the other one and, as a consequence, both should be included into a test battery for the assessment of sediment toxicity. Recommendations and Perspectives  Both plant assays were shown to be reliable tools for the evaluation of the eco-toxicological risk potentials of pore water and solid-phase sediment. They should become a complement to the standardised test battery generally used for comprehensive hazard assessment. ESS-Submission Editor: Dr. Ulrike Kammann (ulrike.kammann@ifo.bfa-fisch.de)  相似文献   
54.

Goal, Scope and Background  

Based on a bioassay battery covering only primary producers and consumers as well as degraders, the potential ecological hazard of sediments to vertebrates cannot be estimated comprehensively. Therefore, there is an urgent need to develop and standardize integrated vertebrate-based test systems for sediment investigation strategies. Whereas vertebrate-based in vitro systems have frequently been used for the investigation of aqueous samples, there is a significant lack of whole sediment assays. Thus, the purpose of the present study was: (1) to develop a rapid and reliable, but comprehensive method to investigate native sediments and particulate matters without preceding extraction procedures; (2) to compare the hazard potential of solid phase sediments to the effects of corresponding pore waters and organic extracts in order to characterize the bioavailability of the particle-bound pollutants; and (3) to relatively evaluate the embryotoxic effects of sediments from the catchment areas of the rivers Rhine, Neckar and Danube.  相似文献   
55.
Goal, Scope and Background. Based on a bioassay battery covering only primary producers and consumers as well as degraders, the potential ecological hazard of sediments to vertebrates cannot be estimated comprehensively. Therefore, there is an urgent need to develop and standardize integrated vertebrate-based test systems for sediment investigation strategies. Whereas vertebratebased in vitro systems have frequently been used for the investigation of aqueous samples, there is a significant lack of whole sediment assays. Thus, the purpose of the present study was: (1) to develop a rapid and reliable, but comprehensive method to investigate native sediments and particulate matters without preceding extraction procedures; (2) to compare the hazard potential of solid phase sediments to the effects of corresponding pore waters and organic extracts in order to characterize the bioavailability of the particle-bound pollutants; and (3) to relatively evaluate the embryotoxic effects of sediments from the catchment areas of the rivers Rhine, Neckar and Danube. Methods (or Main Features).  To investigate the toxicity of sediment samples on vertebrates, the standard embryo toxicity test with the zebrafish (Danio rerio; Hamilton-Buchanan 1922) according to DIN 38415-6 was modified with respect to exposure scheme and toxicological endpoints. Sediments from the catchment area of the Neckar River were assessed using pore waters, acetonic extracts and native sediments in order to get inside into the potential bioavailability of particle-bound pollutants. A comprehensive test protocol for the investigation of native sediments in the embryo toxicity test with the zebrafish is presented. Results and Discussion.  The fish embryo assay with Danio rerio can be carried out with both aqueous and organic sediment extracts as well as native (whole, solid phase) sediment samples. Elongation of exposure time from 48 to up to 196 h significantly increased the mortality. Using the fish egg assay with native sediments, a broad range of embryotoxic effects could be elucidated, including clear-cut dose-response curves for the embryotoxic effects of contaminated sediments; in contrast, absence of embryotoxic effects could be demonstrated even for the highest test concentrations of unpolluted sediments. With native sediments, embryotoxicity was clearly higher than with corresponding pore waters, thus corroborating the view that — at least for fish eggs — the bioavailability of particle-bound lipophilic substances in native sediments is higher than generally assumed. The relative ranking of sediment toxicity was identical using both native sediments and sediment extracts, EC20 values of the latter, however, being eight time lower higher than with the native sediments. A comparison of the embryo toxic effects of samples from the Neckar area with locations along the Rhine and Danube rivers elucidated a broad range of results, thus indicating different levels of contamination. Conclusions.  A modified protocol of the zebrafish embryo test allows the assessment of sediment toxicity in both aqueous extracts and native sediments. The isolated investigation of pore waters may result in a clear-cut underestimation of the bioavailability of lipophilic particle-bound substances (as determined by native sediments). Recommendations and Perspectives.  The zebrafish embryo test with native (whole, solid phase) sediments appears very promising for the evaluation of the bioavailable fraction of lipophilic particle-bound substances and can therefore be recommended for the evaluation of vertebrate toxicity in tiered sediment test strategies and dredging directives such as the HABAB-WSV. Whereas acetone extracts may be tested as a rough estimation of embryotoxicity, native sediment samples will provide a more comprehensive and realistic insight into the bioavailable hazard potential  相似文献   
56.
57.
The objectives of this study were to estimate conservation potential of Vietnamese local breeds and to investigate optimal allocation of conservation funds to maximize genetic diversity conserved between these breeds. Twenty-nine microsatellites were genotyped in 353 individuals from nine Vietnamese local chicken breeds and two chicken breeds of Chinese origin. The Vietnamese chicken breeds were sampled from the northern and southern parts of Vietnam while the two Chinese breeds have been kept as conservation flocks at the National Institute of Animal Sciences, Hanoi. The Weitzman approach was used to assess alternative strategies for conserving genetic diversity between breeds. Three different models, which reflect the range of possible functions in typical conservation situations, were applied. An average extinction probability of 48.5% was estimated for all Vietnamese chicken breeds. The highest conservation potential was found in the Te, Dong Tao and Ac chicken breeds, whereas the lowest corresponding values were observed in the Ri and Mia chicken breeds. The conservation funds were mainly allocated to the same three breeds (Te, Dong Tao and Ac) under all three models. This study suggests that conservation potential of the Vietnamese chicken breeds varies considerably. Population priorities for allocation of conservation funds in this study do not depend on the cost model used. The three breeds (Te, Dong Tao and Ac) with the highest conservation potential should be the prime candidates to be allocated conservation funds if the conservation budgets are limited.  相似文献   
58.
A reference horse‐breeding programme with 13 500 foals each year was modelled with ZPLAN+. This new software for the optimization of the structures in breeding programmes is based on ZPLAN. In two scenarios, the implementation of a rigorous selection of mares was implemented. In scenario I, the mare performance test was the point of selection, while in scenario II, further information on 20 competitions in two more years is available. These selected mares were used for embryo transfer (ET), partly in combination with multiple ovulation (MOET). The selection intensity and the number of foals out of (MO)ET were varied in both scenarios. It was expected that 250, 500 and 1000 mares are available for selecting 20, 50, 100 or 200 donor mares each year. The number of foals out of (MO)ET was varied between one and six foals per donor mare and year. Donor mares were used for ET for 4 years. It became clear that with high selection intensities of donor mares and high reproduction rates of them, the yearly genetic gain in a horse‐breeding programme could increase over a large range. In scenario II, the additional information on 20 competitions increased the accuracy of the selection index to 0.85. With 200 selected donor mares of 1000 available mares and six foals per year, the genetic gain could almost be doubled compared to the reference scenario. The implementation of ET and a related higher usage of few selected mares entails rising costs and a reduction in the genetic variance. In the most extreme MOET scenario, the effective population size was reduced by 19% relative to the reference scenario. Only if the increase in genetic gain can be converted into higher return for the breeders, the implementation of (MO)ET schemes is a realistic and sensible option for horse‐breeding programmes.  相似文献   
59.

Background, aim, and scope

The Mecklenburg Bight (Western Baltic Sea) near Luebeck, Germany was historically used to dump industrial waste at sea and, thus, sediments in some regions are highly polluted at present. While earlier studies identified hot spots of chemical pollution, little is known about biological activities and impacts on exposed marine organisms. This study aimed to assess the pollution in the Mecklenburg Bight to determine the degree of contamination with sediment-bound polycyclic aromatic hydrocarbons (PAHs) as well as biological activities.

Materials and methods

Sediment cores with a depth of 30 cm were sampled at a dumping site and at a reference site, sliced in distinct layers, freeze-dried, and processed using the accelerated solvent extraction method. Sediment was characterized measuring total organic carbon (TOC) and soot contents. Concentrations of the 16 EPA-PAHs were determined with chemical analysis (gas chromatography–mass spectroscopy) in each sediment slice and referred to the determined TOC content. Further on, in vitro biotests were applied to determine toxic effects of contaminants in the sediment. The acute neutral red retention assay indicated no specific cytotoxic effects. Arylhydrocarbon receptor (AhR)-mediated activities were measured using the mechanism-specific 7-ethoxyresorufin-O-deethylase induction assay. Both biotests were performed with rainbow trout (Oncorhynchus mykiss) liver cells (RTL-W1). Analyzed compound concentrations and biological activities were given in toxicological equivalent concentrations (chem- and bio-TEQs) to determine shares of analyzed EPA-PAHs to the overall activity.

Results

TOC and soot contents indicated a significant alteration through the sediment core at the dumping site. EPA-PAH concentrations were referred to TOC and indicated elevated concentrations at the dumping site. Maximum PAH concentrations (14 to 16 cm depth; 5.44 µg/g TOC) were 300-fold increased at the dumping site, compared to the reference site (4 to 6 cm depth; 0.017 µg/g TOC). Cytotoxicity as determined in the neutral red retention assay was elevated in some layers at the dumping site (maximum in 4 to 6 cm depth; NR50?=?14 mg/ml), but not correlated with TOC or soot contents. Ah receptor agonist activities were clearly elevated in highly PAH-loaded layers at both sites. At the dumping site, maximum activities were determined reflected by a bio-TEQ of 223,000 pg/g (19 to 22 cm), in contrast to a bio-TEQ of 41,000 pg/g (6 to 8 cm) at the reference site. Further on, shares of EPA-PAHs to the overall activity were determined and contributed >40% at the dumping site and between 4% and 17% at the reference site. Chem-TEQs were found to exceed bio-TEQs in a depth of 11 to 22 cm, indicating the presence of Ah receptor antagonistic or inhibitive compounds.

Discussion

Sediments from the dumping site were determined to be highly contaminated and caused toxic effects in depths that are known to be influenced by dumping activities. In contrast, the reference sediment indicated only near to surface layers to be minor contaminated. In comparison with highly polluted sediments from other marine sites, the contamination of the dumping site could be ranked as elevated. Chem-TEQs exceeding bio-TEQs in a depth of 11 to 22 cm seem to be caused by AhR antagonistic compounds in the dumped material. Furthermore, particle-bound PAH concentrations assessed in this study were discussed against freely dissolved concentrations in interstitial water, as determined in a different study with the same sediment core.

Conclusions

Sediments in the inner Mecklenburg Bight could be shown to be highly contaminated, at least with PAHs, causing articulate increased Ah receptor-mediated activities. Marine organisms may be exposed to these contaminants, in particular when inhabiting the sediment.

Recommendations and perspectives

Further research activities should extend the range of chemically analyzed pollutants and applied biotests and endpoints. Monitoring should close the gap between analytical methods in the laboratory and the field to determine possible impacts on organisms at site.  相似文献   
60.
Background, aim, and scope  Ecotoxicological risk assessment of sediments is usually based on a multitude of data obtained from tests with different endpoints. In the present study, a fuzzy logic-based model was developed in order to reduce the complexity of these data sets and to classify sediments on the basis of results from a battery of in vitro biotests. Materials and methods  The membership functions were adapted to fit the specific sensitivity and variability of each biotest. For this end, data sets were categorized into three toxicity levels using the box plot and empirical methods. The variability of each biotest was determined to calculate the range of the gradual membership. In addition, the biotests selected were ranked according to the biological organisation level in order to consider the ecological relevance of the endpoints measured by selected over- or underestimation of the toxicity levels. In the next step of the fuzzy logic model, a rule-base was implemented using if...and...then decisions to arrive at a system of five quality classes. Results  The results of the classification of sediments from the Rhine and Danube Rivers showed the highest correlation between the biotest results and the fuzzy logic alternative based on the empirical method (i.e. the classification of the data sets into toxicity levels). Discussion  Many different classification systems based on biological test systems are depending on respective data sets; therefore, they are difficult to compare with other locations. Furthermore, they don‘t consider the inherent variability of biotests and the ecological relevance of these test systems as well. In order to create a comprehensive risk assessment for sediments, mathematical models should be used which take uncertainties of biotest systems into account, since they are of particular importance for a reliable assessment. In the present investigation, the variability and ecological relevance of biotests were incorporated into a classification system based on fuzzy logic. Furthermore, since data from different sites and investigations were used to create membership functions of the fuzzy logic, this classification system has the potential to be independent of locations. Conclusions  In conclusion, the present fuzzy logic classification model provides an opportunity to integrate expert knowledge as well as acute and mechanism-specific effects for the classification of sediments for an ecotoxicological risk assessment. Recommendations and perspectives  In order to achieve a more comprehensive classification, further investigation is needed to incorporate results of chemical analyses and in situ parameters. Furthermore, more discussions are necessary with respect to the relative weight attributed to different ecological and chemical parameters in order to obtain a more precise assessment of sediments.  相似文献   
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