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11.
This article examines the question of how well the rangeland management profession has served conservation of patterns and processes that support multiple ecosystem services. We examine the paradigms under which rangeland management operates and argue that our profession developed under the utilitarian paradigm with the primary goals of sustainable forage for livestock production. While optimization of multiple rangeland products and services has always been a consideration, a comprehensive set of principles have not be been developed to advance this concept. We argue that fire and grazing, often viewed as mere tools used for production goals, should rather be viewed as essential ecosystem processes. Rangeland management continues to operate under the utilitarian paradigm appropriate to societal values of the 20th century and by and large has failed to provide management guidance to reverse degradation of several highly valued ecosystem services. We support this argument with evidence that biodiversity has declined on rangelands in the past half century and that much of this decline is due to management goals that favor a narrow suite of species. The full suite of ecosystem services valued by society will only benefit by management for heterogeneity, which implies that there is no one goal for management and that landscape-level planning is crucial. Explicitly incorporating heterogeneity into state-and-transition models is an important advancement not yet achieved by our profession. We present new principles for rangeland management formed on the basis of conservation of pattern and process. While recognizing that many rangelands have significant deviations from historic plant communities and disturbance regimes, we suggest that management for conservation of pattern and process should focus on fire and grazing to the extent possible to promote a shifting mosaic across large landscapes that include patches that are highly variable in the amount of disturbance rather than the current goal of uniform moderate disturbance.  相似文献   
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Raf kinases have been linked to endothelial cell survival. Here, we show that basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) differentially activate Raf, resulting in protection from distinct pathways of apoptosis in human endothelial cells and chick embryo vasculature. bFGF activated Raf-1 via p21-activated protein kinase-1 (PAK-1) phosphorylation of serines 338 and 339, resulting in Raf-1 mitochondrial translocation and endothelial cell protection from the intrinsic pathway of apoptosis, independent of the mitogen-activated protein kinase kinase-1 (MEK1). In contrast, VEGF activated Raf-1 via Src kinase, leading to phosphorylation of tyrosines 340 and 341 and MEK1-dependent protection from extrinsic-mediated apoptosis. These findings implicate Raf-1 as a pivotal regulator of endothelial cell survival during angiogenesis.  相似文献   
14.
Active remote sensing and grain yield in irrigated maize   总被引:2,自引:0,他引:2  
Advances in agricultural technology have led to the development of active remote sensing equipment that can potentially optimize N fertilizer inputs. The objective of this study was to evaluate a hand-held active remote sensing instrument to estimate yield potential in irrigated maize. This study was done over two consecutive years on two irrigated maize fields in eastern Colorado. At the six- to eight-leaf crop growth stage, the GreenSeeker? active remote sensing unit was used to measure red and NIR reflectance of the crop canopy. Soil samples were taken before side-dressing from the plots at the time of sensing to determine nitrate concentration. Normalized difference vegetation index (NDVI) was calculated from the reflectance data and then divided by the number of days from planting to sensing, where growing degrees were greater than zero. An NDVI-ratio was calculated as the ratio of the reflectance of an area of interest to that of an N-rich portion of the field. Regression analysis was used to model grain yield. Grain yields ranged from 5 to 24 Mg ha?1. The coefficient of determination ranged from 0.10 to 0.76. The data for both fields in year 1 were modeled and cross-validated using data from both fields for year 2. The coefficient of determination of the best fitting model for year 1 was 0.54. The NDVI-ratio had a significant relationship with observed grain yield (r 2 = 0.65). This study shows that the GreenSeeker? active sensor has the potential to estimate grain yield in irrigated maize; however, improvements need to be made.  相似文献   
15.
Despite the fact that the northern bobwhite (Colinus virginianus Linnaeus; hereafter, bobwhite) is one of the most well-studied and widely distributed wildlife species in North America, we know little about how bobwhite respond to oil and gas infrastructure. We investigated the impacts of oil and gas development on space use of bobwhite using a multiseason approach. We captured and monitored bobwhite in the breeding season (1 April–30 September, n = 135 individuals) and nonbreeding season (1 October–31 March, n = 30 coveys) and modeled their habitat selection in a resource-utilization function (third order, within home range selection) and resource-selection function (second order, home range selection) format. Generally, energy infrastructure effects on bobwhite were neutral, but breeding season bobwhite did select for areas near low-traffic roads (β = ? 0.31 ± 0.15 SE). In the nonbreeding season, coveys selected for areas within their home range with a limited viewshed (i.e., areas with limited visibility of anthropogenic structures; β = ? 0.03 ± 0.02 SE). Selection differed between sexes for well pads (t = ? 2.12, P = 0.04) but was otherwise similar. At the level of home range selection, bobwhite exhibited a preference for areas with a low density of oil and gas wells and a high density of low-traffic roads during both the breeding and nonbreeding seasons (breeding: βwell = ? 0.14 ± 0.02, βroad = 0.26 ± 0.27; nonbreeding: βwell = ? 0.08 ± 0.03, βroad = 0.16 ± 0.03). As a generalist species, bobwhite appear to be largely tolerant of energy infrastructure and associated disturbances at moderate levels of development but may be sensitive to high densities of oil and gas pads.  相似文献   
16.
Recent opposition to the rangeland management paradigm of achieving uniform, moderate grazing across entire landscapes has emerged because heterogeneity is recognized as the foundation of biodiversity, ecosystem resilience, and multifunctionality of agricultural landscapes. Agriculture production goals appear to drive the traditional rangeland management focus on homogeneity and uniformity. To determine if preference for homogeneity is a broadly applicable social construct or one limited to agricultural producers, we determined preferences for heterogeneous grassland landscapes expressed by three study populations—managers of working lands (ranchers), natural resource professionals (grassland/rangeland specialists), and the general population living in rangeland regions within the US Great Plains. We distributed surveys that included photographs of landscapes and patterned images to assess preference. Preference for heterogeneous landscapes among ranchers, natural resource professionals, and the general population in our study area were generally consistent with the central paradigm of managing rangeland for homogeneity. However, we discovered that people, across geographic location and population group, clearly prefer heterogeneous patterned images to homogeneous patterned images. This suggests that preference for homogeneity is acquired.  相似文献   
17.
Objective – To determine the safety and efficacy of high‐dose fomepizole compared with ethanol (EtOH) in cats with ethylene glycol (EG) toxicosis. Design – Prospective study. Setting – University veterinary research laboratory. Animals – Thirteen cats. Interventions – Two cats received injections of high‐dose fomepizole (Study 1). Three cats received lethal doses of EG and fomepizole treatment was initiated 1, 2, or 3 hours later (Study 2). Eight cats received a lethal dose of EG and were treated with fomepizole or EtOH (Study 3). Cats treated with fomepizole received 125 mg/kg IV initially, then 31.25 mg/kg at 12, 24, and 36 hours. Cats treated with EtOH received 5 mL of 20% EtOH/kg IV initially, then every 6 hours for 5 treatments, then every 8 hours for 4 treatments. Cats also received fluids and supportive therapy as needed. Measurements and Main Results – Clinical signs were monitored and serial blood analyses performed. Cats receiving fomepizole experienced mild sedation but no biochemical evidence of toxicity. Cats receiving fomepizole for EG intoxication survived if therapy was initiated within 3 hours of EG ingestion. One of the 6 developed acute renal failure (ARF) but survived. Only 1 of the 3 cats treated with EtOH 3 hours following EG ingestion survived; 2 developed ARF and were euthanized. Cats treated 4 hours following EG ingestion developed ARF, whether treated with EtOH or fomepizole. Conclusions – Fomepizole is safe when administered to cats in high doses, prevents EG‐induced fatal ARF when therapy is instituted within 3 hours of EG ingestion, and is more effective than treatment with EtOH.  相似文献   
18.
Commercially available nylon cable ties were used as a method of internal fixation for displaced rib fractures in 8 equine neonates. The procedure was effective, well-tolerated, rapid, and inexpensive. The use of nylon cable ties as internal fixation for displaced rib fractures in foals is an effective surgical procedure.  相似文献   
19.
Olecranon fracture is a common orthopedic problem in juvenile horses. Prognosis for complete fracture healing when various methods of internal fixation are used is good; however, the impact of olecranon fracture stabilization on the likelihood that foals will start on a racecourse is unknown. Medical records of foals undergoing internal fixation for an olecranon fracture were reviewed. The dam's foaling records were obtained and lifetime racing records were then retrieved for both the affected foals and 1 of their siblings. Twenty-two of 24 repaired fractures healed completely, subsequently, 16 of the foals started in at least 1 race. Statistical calculations suggest that when compared with their siblings, the occurrence of olecranon factures requiring internal fixation in juvenile racehorses will not significantly reduce the likelihood that they will race; however, the siblings had significantly more lifetime race starts and higher career earnings.  相似文献   
20.
Understanding how energy infrastructure affects local biodiversity and soil characteristics is important for informing restoration and management. However, the rapid rate of modern oil and gas development is beyond the limit of current knowledge and mitigation strategies. In a mixed-grass prairie in western Oklahoma, we assessed the presence and directionality of biodiversity and environmental gradients associated with energy development in an observational framework. Specifically, we sampled arthropods, vegetation, soil temperature, and soil moisture on the edge of active oil well pads and at 1 m, 10 m, and 100 m away from the well pad. Though variable, the abundance and biomass of most arthropod orders was lower on the pad and 1 m away compared with 10 m and 100 m away, suggesting that the pad itself negatively influenced arthropods but that these effects were limited in spatial extent. However, vegetation structure and composition varied more extensively. Vegetation height, shrub cover, and warm season grass cover increased sixfold, threefold, and fourfold, respectively, from on the oil pad to 100 m away. Forb cover was 5 × higher at 10 m from the well pad than on the pad, 1 m away, and 100 m away from the pad. Soil surface temperature was lower at sites farther from well pads, but we found no relationship between soil moisture and distance from well pad. Well pad effects on arthropods and soil temperature appear to be limited to the pad itself, though long-term changes in vegetation structure extend significantly beyond the well footprint and demand a better understanding of the effectiveness of restoration activities around well pads.  相似文献   
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