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21.
Journal of Pest Science - Yield loss caused by insect pests remains a substantial problem in agriculture. Chemical control, with potential negative effects on non-target organisms, is still the...  相似文献   
22.
The need to integrate non-market ecosystem services into decision-making is widely acknowledged. Despite the exponentially growing body of literature, trade-offs between services are still poorly understood. We conducted a systematic review of published literature in the Nordic countries (Denmark, Norway, Sweden and Finland) on the integration of non-market forest ecosystem services into decision-making. The aim of the review was two-fold: (1) to provide an overview of coverage of biophysical and socio-economic assessments of non-market ecosystem services in relation to forest management; (2) to determine the extent of the integration of biophysical and socio-economic models of these services into decision support models. Our findings reveal the need for wider coverage of non-market ecosystem services and evidence-based modelling of how forest management regimes affect ecosystem services. Furthermore, temporal and spatial modelling of ecosystem impacts remains a challenge. We observed a few examples of multiple non-market services assessments. Integration of non-market services into decision support was performed with either biophysical or socio-economic models, often using proxies and composite indicators. The review reveals that there is scope for more comprehensive and integrated model development, including multiple ecosystem services and appropriate handling of forest management impacts.  相似文献   
23.
The influence of the intensity and timing of precommercial thinning (PCT) on stand development and financial return was studied in Scots pine stands. Functions describing the early development of the stand structure after PCT were developed. The functions were based on 195 plots within 41 PCT experiments in Sweden. The dimension distribution of the established stand was estimated and used as input to the decision support system Heureka, to simulate the stand development until final felling. The studied treatments included PCT to 1000, 2000 and 3000?stems?ha?1 at mean heights of 2, 4 and 6 m. Separate simulations were carried out for different site fertilities. Mean annual volume increment increased with increasing number of stems after PCT whereas the timing of PCT had only a small effect. The land expectation value (LEV) generally decreased with increasing mean height at PCT, primarily because of the increased cost of PCT. LEV decreased with increasing number of stems after PCT at low fertility sites whereas only minor differences were found for PCT to 1000 and 2000?stems?ha?1 at medium and high fertility sites. The general pattern persisted when different scenarios of future timber quality were simulated.  相似文献   
24.
Hyaluronan is involved in fundamental reproductive events such as sperm storage in the female reproductive tract, fertilization, and early embryo development, these functions are presumably mediated by its major cell surface receptor, CD44. The present study was conducted to investigate the presence and localization of CD44 in the bovine oviductal epithelium, using immunohistochemical and Western blot methods on tissue sections and epithelial cell extracts collected from the uterotubal junction (UTJ), isthmus, and ampulla of animals in the oestrus or luteal phase of the oestrous cycle. While positive immunolabelling for CD44 was found on the ad-luminal surface and supra-nuclear region of epithelial cells in all tubal segments investigated, in the UTJ, there were epithelial cells in which the entire cytoplasm positively stained. We found no differences in terms of CD44-positive staining between the different stages of the oestrous cycle. Presence of CD44 was detected by Western blotting in the tubal epithelium as a single band at 200 kDa. Although it appeared in all tubal segments, the expression of CD44 protein was more accentuated in the sperm reservoir (UTJ) than in the other segments. This is the first time CD44 has been detected in the epithelium of the tubal sperm reservoir in cattle, suggesting a pathway for the action of hyaluronan in this segment.  相似文献   
25.
DNA fragmentation of frozen‐thawed feline epididymal sperm from corpus and cauda regions was evaluated by three different techniques. The DNA fragmentation index (DFI) was compared between techniques: the sperm chromatin structural assay (SCSA®), acridine orange staining techniques (AOT) and the sperm chromatin dispersion (SCD). There were significant differences in DFI among the techniques (p < 0.05) with no correlations. Only DFI values obtained from SCD revealed a significantly higher DFI in corpus compared with cauda spermatozoa (p < 0.05). The discrepancy between techniques might be due to the sensitivity of each technique, differences in severity of DNA damaged that can be detected. The difference in DFI between epididymal regions from SCD technique might indicate different maturational stages of spermatozoa, with less chromatin condensation of spermatozoa in corpus compared with cauda epididymis.  相似文献   
26.
Assessing the timescales of recovery, by the use of dynamic models, will be used as input to the policy process to abate acidification. In this study the multilayer dynamic soil chemistry model SAFE was applied to 16 forest sites in Sweden, covering a sulfur deposition gradient of 1.2–11 kg S/ha/yr. Soil samples were collected at all sites and the pH and sulfate concentration dependent isotherm, used for modeling sulfate adsorption in SAFE, was parameterized for every site. A new way of implementing the nutrient uptake distribution in SAFE was developed, which allows the uptake distribution between layers in the rooting zone to vary with time, depending on the availability of base cations in the individual layers. Model output was compared to measurements of base cation concentration, total inorganic Al, pH and Bc/Al both site-by-site and cumulatively for all sites, and the usefulness of these comparisons is discussed from a policy viewpoint. Future projections of recovery show that the overall recovery, expressed as minimum Bc/Al ratio > 1 in the rooting zone, is slow. Assuming full implementation of the UNECE LRTAP Gothenburg Protocol and no further emission reductions thereafter, 44% of the modeled sites still have a Bc/Al ratio below 1 in 2100 in some soil layer within the rooting zone.  相似文献   
27.
It is important that measures to maintain biodiversity are taken in a way that is cost-effective for the landowner. We analyzed the cost-effectiveness of silvicultural measures that aim at increasing the substrate availability for red-listed (species that are threatened, near threatened or where species probably are threatened but data is deficient) saproxylic (wood-inhabiting) organisms. We modelled stands of Norway spruce (Picea abies) in three regions of Sweden by using computer simulations and a database with substrate requirements of saproxylic beetles and cryptogams on the Swedish Red-List. Conclusions concerning cost-effectiveness of silvicultural measures depend on the extinction thresholds of the species they are intended to conserve; measures that generate only small amounts of coarse woody debris (CWD) may provide too little substrate to be useful for species with high extinction thresholds. In northern Sweden, forestland is relatively inexpensive, so a cost-effective strategy to increase the amount of spruce CWD was to set aside more forests as reserves. In central and southern Sweden, more emphasis should instead be given to increasing the amount of CWD in the managed forest. The regulations by the Forest Stewardship Council (FSC) could be made more cost-effective by prescribing creation of more high stumps and retention of larger amounts of naturally dying trees. Large-sized CWD, CWD from slow-growing trees, and CWD in late decay stages are substrate types that were particularly rare in managed forest in relation to unmanaged forests. Manual soil scarification and retention of living trees are measures that can increase the proportion of these underrepresented CWD types.  相似文献   
28.
The European steady-state Simple Mass Balance (SMB) model and the dynamic soil acidification model SAFE were used to assess the risk of future forest soil acidification in Switzerland. 2010 deposition forecasts on a 150×150 km grid resolution as well as corresponding ecosystem protection levels were obtained from RAINS model runs based on the 1999 Gothenburg Protocol obligations under the UN/ECE LRTAP Convention. Deposition values for 2010 on the national resolution were derived by scaling down present 1×1 km deposition values according to the deposition trends at the 150×150 km grid resolution. Meeting the Protocol obligations will reduce the percentage of Swiss forest ecosystems not protected against acidification between 1990 and 2010 from 41 to 4% according to the RAINS assessment and from 63 to 16% according to the assessment with the SMB at the 1×1 km resolution. The dynamic approach indicates, however, that soil conditions may not improve as much as these steady-state models suggest. By 2010, 39% of the sites considered will still have soil solution Bc/Al molar ratios below 1 at least in one soil layer. Nevertheless, deposition reductions obtained from the implementation of the new protocol will prevent the major part of Swiss forest soils from further acidification. Aiming at recovery of the more sensitive forest ecosystems would require emission reductions beyond the Protocol's obligations.  相似文献   
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30.
Outdoor recreation encompasses an array of activities carried out in a multitude of envrionments, including forests. An important motive for participating is the possible mental and physical health benefits gained. Currently, there is an absence of studies which have examined the economic aspects of the health effects from outdoor recreation. The main aim of this study was to use the contingent valuation method to compare the willingness to pay (WTP) for avoiding a hypothetical suspension of outdoor recreation among forest recreationists and hunters in Sweden. The second aim was to analyze the determinants of this WTP change, with emphasis on perceived health states obtained by means of a visual analogue scale. The results showed that changes in health state due to participation as well as visiting frequency were significant predictors of WTP. These findings suggest that health state measures may be useful for assessing health outcomes of outdoor recreation and associated WTP.  相似文献   
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