全文获取类型
收费全文 | 241篇 |
免费 | 11篇 |
国内免费 | 2篇 |
专业分类
林业 | 12篇 |
农学 | 1篇 |
基础科学 | 1篇 |
15篇 | |
综合类 | 69篇 |
农作物 | 2篇 |
水产渔业 | 6篇 |
畜牧兽医 | 102篇 |
园艺 | 5篇 |
植物保护 | 41篇 |
出版年
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 2篇 |
2013年 | 6篇 |
2012年 | 4篇 |
2011年 | 10篇 |
2010年 | 4篇 |
2009年 | 5篇 |
2008年 | 12篇 |
2007年 | 6篇 |
2006年 | 6篇 |
2005年 | 4篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2002年 | 7篇 |
2001年 | 7篇 |
2000年 | 7篇 |
1997年 | 2篇 |
1996年 | 6篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 8篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1974年 | 5篇 |
1973年 | 4篇 |
1972年 | 4篇 |
1971年 | 4篇 |
1970年 | 4篇 |
1968年 | 4篇 |
1967年 | 4篇 |
1966年 | 3篇 |
1965年 | 9篇 |
1964年 | 2篇 |
1962年 | 5篇 |
1960年 | 3篇 |
1903年 | 2篇 |
1900年 | 2篇 |
1895年 | 2篇 |
排序方式: 共有254条查询结果,搜索用时 15 毫秒
101.
Duan Jian J. Van Driesche Roy G. Schmude Jonathan Crandall Ryan Rutlege Claire Quinn Nicole Slager Benjamin H. Gould Juli R. Elkinton Joseph S. 《Journal of pest science》2022,95(3):1081-1090
Journal of Pest Science - Successful management of invasive forest pests with sustainable approaches, such as biological control, is critical to the restoration of the affected or damaged forest... 相似文献
102.
M Villareale L V Gould R H Wasserman A Barr R T Chiroff W H Bergstrom 《Science (New York, N.Y.)》1974,183(125):671-673
Rickets, hypocalcemia, decreased duodenal calcium transport, and reduction of calcium binding protein have been produced in chicks treated with diphenylhydantoin. These effects are directly related to diphenylhydantoin dose and inversely related to the intake of vitamin D(3) (cholecalciferol). 相似文献
103.
104.
Evolutionary time has a characteristic direction as demonstrated by the asymmetry of clade diversity diagrams in large statistical samples. Evolutionary groups generally concentrate diversity during their early histories, producing a preponderance of bottom-heavy clades among those that arise early in the history of a larger group. This pattern holds across taxonomic levels and across differences in anatomy and ecology (marine invertebrates, terrestrial mammals). The quantitative study of directionality in life's history (replacing vague, untestable, and culturally laden notions of "progress") should receive more attention from paleobiologists. 相似文献
105.
106.
Matthew R. Dzialak Dean J. Houchen Seth M. Harju James P. Mudd John J. Wondzell Stephen L. Webb Nicholas P. Gould Jennifer E. Hess Jeffrey B. Winstead 《Landscape Ecology》2013,28(7):1371-1385
Narrow endemism presents challenges to species occurrence modeling particularly when the distribution of key local habitat features changes across space and time as a function of processes operating at larger scales. One need facing conservation in such settings is a better understanding of the biogeographic dynamics of the larger features that govern occurrence of critical local habitat. The Mescalero–Monahans shinnery sands region of western North America is a dynamic landscape where sand shinnery oak interacts with wind-driven sand to establish dune habitat. This ecosystem supports several narrowly endemic dune-dwelling species including the dunes sagebrush lizard. Using near-anniversary satellite and aerial imagery from 1986, 1998, and 2011, we integrated object-based image classification and statistical analysis to develop and validate a spatially explicit estimate of the sand shinnery oak ecosystem, including dynamics associated with its attrition and emergence, at high resolution throughout an 89,849-km2 study area encompassing the range of the dunes sagebrush lizard. The spatial estimate of the distribution and extent of the sand shinnery oak soil-vegetation association validated reasonably well (overall accuracy = 0.79; sensitivity = 0.49; specificity = 0.91) and showed that the association declined 10.3 % in extent during the 25-year assessment window. The presence of sand shinnery oak, patch size, and patch isolation were dynamic across space and time; a regression model showed that smaller, isolated patches on the periphery of the system were more likely to be lost over time whereas larger, less isolated, and centrally distributed patches were more likely to persist or expand. This study details broadly applicable methods to accurately delineate landforms throughout large extents, and offers mapping tools specific to issues surrounding Mescalero–Monahans shinnery sands endemics that are readily amenable to testing, refinement, and application in efforts to focus sustainable landscape management including conservation of endemic species. 相似文献
107.
G.Z. Sass M. Wheatley D.A. Aldred A.J. Gould I.F. Creed 《Biological conservation》2012,147(1):143-152
Surface and near-surface hydrological conditions are not generally considered in the selection of protected-area boundaries; however, these hydrological conditions may be critical in the maintenance of hydrologically driven biodiversity areas and should factor heavily in systematic conservation planning and impact-mitigation efforts. Here we demonstrate the use of Synthetic Aperture Radar (SAR) satellite imagery to model surface and near-surface hydrological dynamics and related vascular-plant species richness surrounding Sundance Provincial Park, Alberta, Canada. Based on a relationship established between field-sampled soil moisture and remote-sensed SAR backscatter coefficient, we generated landscape-scale maps of surface hydrological condition and related vascular-plant species richness surrounding the protected area. After processing, SAR data were classified into three hydrological classes: unsaturated, saturated and inundated. By assembling a multi-year series of SAR images acquired across the natural range of hydrological conditions, the probability of surface saturation and inundation was developed. Using the resulting probability map to select sites for biodiversity assessment, we found relatively strong relationships between total vascular plants (species richness, especially ferns and herbs), and the probability of wet area (both saturated and inundated areas) occurrence. Using this relationship, we mapped vascular-plant species richness across the study region revealing opportunities to mitigate impacts from adjacent developments and to expand the park to increase its ecological value. This study presents an important approach for assessing biodiversity of existing parks and generating valuable input layers that help to define ecologically relevant protected-area boundaries. 相似文献
108.
109.
Involvement of microbial respiratory pathogens in acute interstitial pneumonia in feedlot cattle 总被引:1,自引:0,他引:1
Loneragan GH Gould DH Mason GL Garry FB Yost GS Miles DG Hoffman BW Mills LJ 《American journal of veterinary research》2001,62(10):1519-1524
OBJECTIVE: To evaluate viral and bacterial respiratory pathogens and Mycoplasma spp isolated from lung tissues of cattle with acute interstitial pneumonia (AIP) and cattle that had died as a result of other causes. SAMPLE POPULATION: 186 samples of lung tissues collected from cattle housed in 14 feedlots in the western United States. PROCEDURE: Lung tissues were collected during routine postmortem examination and submitted for histologic, microbiologic, and toxicologic examinations. Histologic diagnoses were categorized for AIP, bronchopneumonia (BP), control samples (no evidence of disease), and other disorders. RESULTS: Cattle affected with AIP had been in feedlots for a mean of 1272 days before death, which was longer than cattle with BP and control cattle. Detection of a viral respiratory pathogen (eg, bovine respiratory syncytial virus [BRSV], bovine viral diarrhea virus, bovine herpesvirus 1, or parainfluenza virus 3) was not associated with histologic category of lung tissues. Bovine respiratory syncytial virus was detected in 8.3% of AIP samples and 24.0% of control samples. Histologic category was associated with isolation of an aerobic bacterial agent and Mycoplasma spp. Cattle with BP were at greatest risk for isolation of an aerobic bacterial agent and Mycoplasma spp. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of these results suggests that AIP in feedlot cattle is not a consequence of infection with BRSV. The increased, risk of isolation of an aerobic bacterial agent from cattle with AIP, compared with control cattle, may indicate a causal role or an opportunistic infection that follows development of AIP. 相似文献
110.
M S Kerley K A Garleb G C Fahey L L Berger K J Moore G N Phillips J M Gould 《Journal of animal science》1988,66(12):3235-3244
Effects of alkaline hydrogen peroxide (AHP) treatment on cellulose crystallinity and cell wall phenolic monomer and monosaccharide composition were measured using cotton and wheat straw (WS). Two WS treatments were used in this study, Type I WS, for which pH is not regulated during AHP treatment, and Type II WS, for which pH is regulated at 11.5 +/- .2 during AHP treatment. Wheat straw had a lower degree of cellulose crystallinity than cotton, but no differences occurred between treated and untreated substrates. Alkali-labile and nitrobenzene-extractable phenolic monomer concentrations were generally lower for Type I and Type II WS compared with untreated WS. Concentrations of glucose were higher and xylose and arabinose lower in Types I and II WS than in untreated WS. Disappearance of alkali-labile phenolic monomers and cell wall monosaccharides by wethers fed diets containing Type I (Exp. 1) or Type II (Exp. 2) AHP-treated WS were determined. Apparent digestibility of glucose and xylose before the duodenum, and of glucose, xylose and arabinose in the total tract, was greatest (P less than .05) when sheep were fed AHP-treated WS diets in both experiments. In Exp. 2, disappearance of alkali-labile phenolic monomers was greatest (P less than .05) before the duodenum and in the total tract when sheep were fed AHP-treated WS diets. Treatment of WS with AHP modified cell wall composition and increased cell wall monosaccharide digestion by sheep. 相似文献