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51.
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Recognizing the importance of preserving biodiversity and ecosystem services, human society has established extensive protected area networks to conserve these resources in recent decades. Are protected areas working as expected? Empirical coarse-scale assessments of this question across large regions, or even globally, tend to answer “yes”, while fine-scale studies of individual protected areas often and repeatedly answer “no”. We conducted a first fine-scale analysis of Brazil’s extensive Amazonian protected area network (1.8 million km2) and have quantitatively estimated conservation effectiveness in light of changing human development pressures in the surrounding landscape. The overall network maintained intact forest cover for 98.6% of protected forest lands, largely agreeing with previous coarse-scale studies. However, detailed examination of 474 individual protected areas unveils a broad range of efficacy. Many protected areas (544,800 km2) experience default protection simply due to their remoteness. Many others (396,100 km2) have provided highly effective protection in the face of substantial human development pressure. Conversely, 12% (38) of protected areas have failed to protect the 27,300 km2 that they encompass, and another 7% (23) provide only marginal protection of 37,500 km2. Comprehensive landscape assessments of protected area networks, with frequent monitoring at scales matching the patterns of human-caused disturbances, are necessary to ensure the conservation effectiveness and long term survival of protected areas in rapidly changing landscapes. The methods presented here are globally adaptable to all forested protected areas.  相似文献   
53.
Water potential measurements were made, over three winter seasons, on Eucalyptus pauciflora Sieb. ex Spreng. at four elevations extending up to 200 m above the natural tree line in the Snowy Mountains area of southeastern Australia. Shoot water potentials were lowest in winter but never approached lethal levels. Contrary to expectations, there was no gradient of water potential with elevation. This was attributed primarily to the absence of a gradient of soil temperatures once snowpack had developed. Lowest water potentials were observed at air temperatures several degrees above zero, suggesting that transpiration and absorption may be differently affected, with temperatures above and below these values causing higher water potentials. The results suggest that shoot dieback in winter, which is a common phenomenon at alpine tree lines, is not caused by low water potentials in southeastern Australia.  相似文献   
54.
Ten cases of equine Horner's syndrome were reviewed. None of the clinical signs in this series were transient (<48 hours). Sweating and ptosis were consistently observed by the attending clinician in over half of the affected horses. Enophthalmos and prolapse of the third eyelid were not reported consistently. The average duration of the clinical signs was 4.94 months and ranged from 14 days to 15 months. Eight of the ten horses developed associated complications, some of which affected performance. Airway obstruction and impedance of passage of a fiberoptic endoscope due to nasal mucosal edema occurred in five horses. Facial paralysis (4/10) and laryngeal hemiplegia (2/10), which are not direct features of Horner's syndrome, were also observed.  相似文献   
55.
The ocean is affected by multiple anthropogenic stressors including climate change, the effects of which are already evident in many ocean ecosystems. The ABACuS v2 end‐to‐end model together with climate projections from the NEMO‐MEDUSA 2.0 model were used to evaluate the effects of fishing, warming and horizontal and vertical mixing on the southern Benguela upwelling system. Of the drivers examined in this study, warming had the greatest effect on species biomass, with mainly negative effects. The magnitude of the impacts of warming intensified from the RCP 2.6 to the 8.5 emission scenario. Fishing negatively affected demersal and large pelagic fish, which in turn resulted in a biomass increase of forage fish due to a decrease in predation pressure. Water mixing was found to have minor indirect effects on zooplankton biomass and fish. The responses of species and species groups to the combined effects of fishing and warming were approximately equally divided between additive, synergistic and antagonistic. Interpretation of our model results suggests that the southern Benguela system is likely to be affected by climate change, including substantial changes in the abundance of some species important to the region's fisheries. Future planning for fisheries needs to take this into account, including through management that strives to maintain the resilience of key species and the system as a whole. In line with previous studies on the southern Benguela, the results reinforce the importance of including consideration of the indirect and combined impacts of climate change and fishing in management and planning.  相似文献   
56.
Forest edges in the Amazon are very dynamic with ongoing deforestation adding new edges as older edges are eroded. Rates of edge erosion and the composition of edge ages, together with distance from edges, are very important factors in determining the magnitude of forest degradation such as biomass collapse and carbon flux. However, we lack an understanding of how these factors change through time and over the different stages of deforestation. In this study, we quantify the spatial and temporal structures of forest edge in Rondônia, southwestern Amazon, by analyses of 22 years of annual satellite imagery, and discuss the implications for biomass dynamics and forest degradation caused by edges. Our results from three different stages of deforestation (early, intermediate and advanced) reveal that more than 50% of forest edges were eliminated in the first four years after edge creation and only 20% of edges survived more than 10 years. High edge erosion rates in the first year imply that many edges disappear before going through the process of edge-induced biomass collapse. At the early stage of deforestation, young forest edges are predominant, while at the advanced deforestation stage more than 50% of total edges are >10 years old. Rapid erosion is more prevalent in early stages, when young forest edges dominate the landscape. Edge-related biomass collapse is substantially more advanced in heavily deforested regions where forests are mostly surrounded mostly by older edges, but relatively few edges remain at this point.  相似文献   
57.
An ion-suppression reverse phase high pressure liquid chromatographic method is described for determining naphthaleneacetic acid (NAA) residues in apples. Samples are extracted with acidic chloroform, filtered through pre-acidified Hy-Flo Supercel, and cleaned up by acid-base partitioning. The extract can be successfully chromatographed on either a muLiChrosorb NH2 or muBondapak C18 column and quantitated by using a variable wavelength ultraviolet detector set at 220 nm. The mobile phase is acetonitrile-water (20 + 80) buffered to pH 3.5 (MULiChrosorb column) or pH 5.2 (MUBondapak column) and flowing at 1.0--2.0 ml/min. Recoveries ranged from 86 to 98%. The minimum detectable amount was 0.5 ng, which easily permitted the quantitation of 0.01 ppm NAA in 50 g sample. A fluorometric detector was 4 times as sensitive, using an excitation wavelength of 220 mm and monitoring the emission at 340 nm. For this detector, the minimum detectable amount was 0.12 ng NAA.  相似文献   
58.
Many of the world’s fish stocks are depleted as a result of overexploitation, pollution and habitat loss. The 2002 World Summit on Sustainable Development (WSSD) sets a target for fisheries to maintain or restore stocks to levels that can produce the maximum sustainable yield (MSY) by 2015. We assessed the global stock status and found that 68% were at or above the MSY level in 2008 and that the 2015 target is unlikely to be met. We compiled data for eight indicators to evaluate the sustainability of fisheries and the gap to meet the WSSD target. These indicators show that the overall condition of global fisheries is declining, long‐term benefits are being compromised, and pressures on fisheries are increasing despite fisheries policy and management actions being taken by coastal States. We develop a bio‐economic model to estimate the costs and benefits of restoring overfished stocks. Our results show that the global fishing capacity needs to be cut by 36–43% from the 2008 level, resulting in the loss of employment of 12–15 million fishers and costing US$96–358 billion for buybacks. On the other hand, meeting the WSSD goal will increase annual fishery production by 16.5 million tonnes, annual rent by US$32 billion and improve biodiversity and functioning of marine ecosystems. However, progress towards rebuilding has been hindered by an unwillingness or inability to accept the short‐term socio‐economic consequences associated with rebuilding fisheries. Thus, there is a pressing need for integration of rebuilding plans into national political and economic decision‐making.  相似文献   
59.
Fecal egg count (FEC) is an indicative measurement for parasite infection in sheep. Different FEC methods may show inconsistent results. Not accounting for inconsistencies can be problematic when integrating measurements from different FEC methods for genetic evaluation. The objectives of this study were to evaluate the difference in means and variances between two fecal egg counting methods used in sheep—the Modified McMaster (LMMR) and the Triple Chamber McMaster (LTCM); to estimate variance components for the two FEC methods, treating them as two different traits; and to integrate FEC data from the two different methods and estimate genetic parameters for FEC and other gastrointestinal parasite resistance traits. Fecal samples were collected from a commercial Rideau-Arcott sheep farm in Ontario. Fecal egg counting was performed using both LMMR and the LTCM methods. Other parasite resistance trait records were collected from the same farm including eye score (FAMACHA), body condition score (BCS), and body weight (WT). The two FEC methods were highly genetically (0.94) and phenotypically (0.88) correlated. However, the mean and variance between the two FEC methods were significantly different (P < 0.0001). Therefore, re-scaling is required prior to integrating data from the different methods. For the multiple trait analysis, data from the two fecal egg counting methods were integrated (LFEC) by using records for the LMMR when available and replacing missing records with re-standardized LTCM records converted to the same mean and variance of LMMR. Heritability estimates were 0.12 ± 0.04, 0.07 ± 0.05, 0.17 ± 0.06, and 0.24 ± 0.07 for LFEC egg count, FAMACHA, BCS, and WT, respectively. The estimated genetic correlations between FEC and the other parasite resistance traits were low and not significant (P > 0.05) for FAMACHA (r = 0.24 ± 0.32) and WT (r = 0.22 ± 0.19), and essentially zero for BCS (r = −0.03 ± 0.25), suggesting little to no benefit of using such traits as indicators for LFEC.  相似文献   
60.
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