全文获取类型
收费全文 | 46篇 |
免费 | 2篇 |
国内免费 | 3篇 |
专业分类
林业 | 8篇 |
农学 | 2篇 |
基础科学 | 3篇 |
18篇 | |
综合类 | 15篇 |
农作物 | 1篇 |
畜牧兽医 | 2篇 |
园艺 | 2篇 |
出版年
2024年 | 1篇 |
2020年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2012年 | 2篇 |
2011年 | 4篇 |
2010年 | 5篇 |
2009年 | 8篇 |
2008年 | 5篇 |
2007年 | 1篇 |
2005年 | 4篇 |
2004年 | 3篇 |
2002年 | 3篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有51条查询结果,搜索用时 875 毫秒
1.
Environmental assessment methods are needed by agronomists working on the enhancement of cropping systems to meet the demand for more sustainable farming practices. A growing number of operational methods based on a set of indicators have been designed, more for arable crops and livestock than for perennial crops like viticulture. Among them, the INDIGO® method, originally developed for arable crops, offers a compromise between feasibility and predictive quality. Here we present a modified and expanded version of INDIGO® for viticulture. The development of new indicators specific to viticulture and the adaptation of existing ones followed a five step approach: (i) preliminary definition of the objectives and identification of the end-users, (ii) construction of the indicator, (iii) selection of a reference value, (iv) sensitivity analysis and (v) validation. Stakeholders from professional institutions and winegrower organizations were closely associated with step (i) to define the framework and step (ii) to supply technical databases. We designed INDIGO® indicators with all available scientific and expert knowledge which was aggregated into expert systems associating fuzzy subsets or, when possible, quantitative equations.Four indicators; pesticides, nitrogen, energy and soil organic matter, were directly adapted from the initial INDIGO® method, whereas soil cover and frost protection management were new indicators. Potentialities of their use are highlighted by examples of implementation on different scales and for various purposes. 相似文献
2.
3.
Influence of four soil maintenance practices on Collembola communities in a Mediterranean vineyard 总被引:1,自引:0,他引:1
Anglique Renaud Nicole Poinsot-Balaguer Jrme Cortet Jean Le Petit 《Pedobiologia》2004,48(5-6):623-630
We studied the influence of four soil maintenance practices on Collembola communities in the soil of a Mediterranean vineyard: (a) postemergence herbicide with glyphosate; (b) postemergence and pre-emergence herbicides with glyphosate, terbuthylazine, diuron and oryzalin; (c) natural flora and (d) tillage to a depth of 10–15 cm. Total Collembola abundance, species diversity and species richness significantly varied between the four practices. Notably, the practice using postemergence and pre-emergence herbicides had significantly lower values. Identification of Collembola at species level allowed an interspecies comparison and revealed significant differences for the most common species between the four practices, with each practice being characterized by a different set of species. None of the species were found to be significantly more abundant in the plots treated with postemergence and pre-emergence herbicides. 相似文献
4.
Grapevines are extensively grown in the semiarid and arid regions, but little information is available on the variability of energy partitioning and resistance parameters for the vineyard. To address this question, an eddy covariance system was applied to measure energy balance over a vineyard in northwest China during 2005-2006. Result indicated that 2-year average Bowen ratio (β) of vineyard was 1.0, canopy resistance (rc) 289.3 s m−1, aerodynamic resistance (ra) 9.7 s m−1 and climatological resistance (ri) 117 s m−1. This implied that the annual energy was split almost equally between sensible heat and latent heat. Compared to the corresponding values in other ecosystems reported by Wilson et al. [Wilson, K.B., Baldocchi, D.D., Aubinet, M., Berbigier, P., Bernhofer, C., Dolman, H., Falge, E., Field, C., Goldstein, A., Granier, A., Grelle, A., Halldor, T., Hollinger, D., Katul, G., Law, B.E., Lindroth, A., Meyers, T., Moncrieff, J., Monson, R., Oechel, W., Tenhunen, J., Valentini, R., Verma, S., Vesala, T., Wofsy, S., 2002. Energy partitioning between latent and sensible heat flux during the warm season at FLUXNET sites. Water Resource Research 38, 1294-1305.], the vineyard had a higher β, rc and ri than deciduous forests, corn and soybean, and grassland. Such difference was mainly attributed to (1) serious water stress in 2005, which resulted in a greater rc up to 364.4 s m−1; (2) sparse canopy with row spacing of 2.9 m and plant spacing of 1.8 m; (3) warm-dry climate and high attitude (1581 m) along with higher ri and lower psychrometer (54 Pa K−1) in the arid region of northwest China. These characters of vineyard revealed varying process of energy partitioning and surface resistance, and provided a scientific basis in understanding and modeling water and energy balance for the vineyard in the semiarid and arid regions. 相似文献
5.
In an alley cropping experiment, a study was carried out on N2 fixation by Gliricidia sepium, nitrogen (N) accumulation by prunings of Gliricidia, Senna siamea (formerly Cassia siamea) and Gmelina arborea, and the N contribution to associated crops of rice and cowpea.Total N accumulated by the hedgerow trees ranged from 297–524 kg N ha–1 on average but varied between tree species and depended on the growing season. Gliricidia sepium accumulated 370 kg N ha–1 on average and more than half of this came from fixation. Senna siamea and Gmelina arborea served as reference trees for estimating N2 fixation. The estimates of N2 fixation using Gmelina as a reference gave higher estimates than those using Senna.Although the dry matter and nitrogen yields of prunings from the hedgerow trees were high, their relative nitrogen contribution to the associated crops was generally low ranging from 5 to 29%. Higher crop yields and nitrogen contribution were observed with Gliricidia sepium prunings. The low N contribution from prunings was attributed to the lack of synchronization between the N released from the prunings and the crop's demand for N. 相似文献
6.
在西北农林科技大学园艺试验站选择历年葡萄二黄斑叶蝉发生较严重的葡萄品种为调查对象,于2013年4~10月进行系统调查,并采用Taylor幂法则、Iwao回归分析法和Lloyd平均聚块性指标对葡萄二黄斑叶蝉种群聚集扩散情况进行测定分析,研究了其种群空间分布型。结果表明,葡萄二黄斑叶蝉在陕西关中地区1年发生3代,若虫1年出现3个高峰。运用3种空间分布测定指标对葡萄二黄斑叶蝉空间分布型的测定结果均一致,葡萄二黄斑叶蝉在关中地区葡萄园呈聚集分布,个体之间相互吸引,聚集强度随种群密度升高而增加,且种群密度随时序动态变化呈现出扩散-聚集-扩散-聚集的规律。 相似文献
7.
8.
J. Vandermeer 《Agroforestry Systems》1998,40(2):199-206
A simple graphical model is presented illustrating the balance between facilitation and competition necessary for maximizing
crop yield in alley cropping systems. Three functions are composed into the decision function: (1) the percent increase in
crop yield from facilitation resulting from prunings, (2) the amount of prunings resulting from different tree densities,
and (3) the percent reduction in crop yield from competition from trees. The resulting function illustrates how the balance
between facilitation and competition may provide a window of opportunity for the beneficial use of alley crops.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
9.
10.