全文获取类型
| 收费全文 | 53篇 |
| 免费 | 1篇 |
专业分类
| 林业 | 4篇 |
| 农学 | 3篇 |
| 3篇 | |
| 综合类 | 10篇 |
| 农作物 | 6篇 |
| 水产渔业 | 1篇 |
| 畜牧兽医 | 8篇 |
| 园艺 | 9篇 |
| 植物保护 | 10篇 |
出版年
| 2022年 | 1篇 |
| 2021年 | 1篇 |
| 2020年 | 1篇 |
| 2019年 | 2篇 |
| 2018年 | 2篇 |
| 2017年 | 2篇 |
| 2016年 | 3篇 |
| 2014年 | 5篇 |
| 2013年 | 3篇 |
| 2011年 | 4篇 |
| 2009年 | 3篇 |
| 2008年 | 2篇 |
| 2007年 | 1篇 |
| 2006年 | 2篇 |
| 2005年 | 3篇 |
| 2003年 | 2篇 |
| 2000年 | 3篇 |
| 1999年 | 1篇 |
| 1993年 | 4篇 |
| 1991年 | 1篇 |
| 1989年 | 1篇 |
| 1988年 | 1篇 |
| 1987年 | 2篇 |
| 1986年 | 1篇 |
| 1983年 | 1篇 |
| 1979年 | 1篇 |
| 1963年 | 1篇 |
排序方式： 共有54条查询结果，搜索用时 15 毫秒
1.
Landscape Ecology - Pollinator declines and functional homogenization of farmland insect communities have been reported. Mass-flowering crops (MFC) can support pollinators by providing floral... 相似文献
2.
3.
In Germany, sugar beet is often rotated with 2 years of cereal. Extensive fallow periods between cereal harvest and autumn primary tillage allow for a weed flora to develop. Broad‐leaved weeds could potentially be alternate hosts for the common nematode Heterodera schachtii, one of the most important pests of sugar beet. Between 2009 and 2012, annual weeds developing in cereal stubble fields during July to mid‐October in the season prior to sugar beet were surveyed, including known hosts of H. schachtii. Yearly weather patterns and agronomic practices possibly impacted weed species composition and weed population densities. During September, Chenopodium album, Cirsium arvense, Convolvulus arvensis, Mercurialis annua, Polygonum spp., Solanum nigrum and Sonchus spp. occurred at the highest frequencies. Weed hosts of H. schachtii were present, but densities, frequencies and uniformity were limited. In 2010 and 2011, staining for nematodes in roots revealed juvenile penetration of some weeds but few adult stages. No indication of nematode reproduction of H. schachtii was found on these weed hosts. A fairly stable weed flora was detected on stubble fields that could provide some carry over for weed species. An elevated risk for nematode population density build‐up on these weeds was not found and management of these weeds at the observed densities during the stubble period for nematological reasons appeared unnecessary. 相似文献
4.
Journal of Plant Diseases and Protection - Sudden death syndrome (SDS) of soybean caused by Fusarium virguliforme has increased in geographical distribution in the North Central region of the U.S.... 相似文献
5.
ABSTRACT Sudden death syndrome (SDS) of soybean is caused by the soilborne Fusarium solani f. sp. glycines (synonym F. virguliforme). In a sequential approach, two multifactor factorial-design microplot experiments were conducted to investigate the effects of fungal infestation levels and soil moisture on both root necrosis and foliar SDS severity, and the interaction between F. solani f. sp. glycines and Heterodera glycines in fumigated versus nonfumigated soil. In 2003, soybean cv. Spencer was grown in nonfumigated or methyl bromide-fumigated soil and infested with increasing levels of F. solani f. sp. glycines, either under rainfall or irrigated after growth stage V6/R1. In 2004, interactions between F. solani f. sp. glycines and H. glycines were explored in a factorial inoculation design in fumigated or nonfumigated soil, planted to Williams 82 or Cyst-X20-18. In both years, higher levels of foliar SDS severity and root necrosis were found in F. solani f. sp. glycines-infested soils with H. glycines than in soils without the nematode on the soybean cultivars susceptible to both pathogens. Both natural infestations of H. glycines in 2003 and artificially amended populations of H. glycines in 2004 contributed to higher foliar SDS severity. More severe foliar SDS symptoms always were associated with more root necrosis, but elevated levels of root necrosis did not predict severe leaf symptoms. In contrast to the critical role of H. glycines, increasing fungal infestation levels had no significant effects on increasing either foliar SDS symptoms or root necrosis. Effects of moisture regime and fungal infestation levels also were examined in factorial greenhouse and growth chamber experiments. High soil moisture resulted in higher levels of SDS root necrosis. In the greenhouse, root necrosis increased at a higher rate in low soil moisture than the rate in high soil moisture. The two pathogens acted as a complex and the disease development was strongly dependent on high soil moisture. 相似文献
6.
J. Schittenhelm S. Westphal Susanne Toder E. Wagner 《European Journal of Forest Research》1993,112(1):240-250
Zusammenfassung Die Auswirkungen verschiedener Stre?faktoren auf das antioxidative System wurden in sechsj?hrigen Klonfichten untersucht.
überflutung und Dunkelheit hatten nur geringen Einflu?. Im Gegensatz dazu wirkten sich die Stre?faktoren Trockenheit, K?lte,
Starklicht und sehr hohe Ozonkonzentrationen stark auf das antioxidative System aus. Die Effekte waren jedoch nicht einheitlich,
sondern waren je nach Stre?faktor unterschiedlich. Dies wird als ein Hinweis dafür gewertet, da? die Sch?den bei diesen Stre?faktoren
durch unterschiedliche toxische Sauerstoffspezies entstehen und da? sich die Sch?den unter Freilandbedingungen synergistisch
verst?rken k?nnen.
The antioxidative system of Norway spruce: Effects of different stress factors
Summary The effects of different stress factors on the antioxidative system of 6-year-old Norway spruces of the same clone were examined. Flooding and permanent darkness had only minor effects. On the other hand drought, chilling, intense light, and very high ozone concentrations showed strong but distinct consequences. This indicates that the damages by these stress factors are due to different toxic oxygen species, and that the stress factors could produce synergistic damages under natural field conditions.相似文献
7.
Marcella Teixeira Linhares Joo Pedro Scussel Feranti Gabriela Pesamosca Coradini Letícia Reginato Martins Arthur Rodrigues Martins Vanessa Zanchi Sarturi Felipe Baldissarella Gavioli Marco Augusto Machado Silva Michelli Westphal de Ataíde Luciana Gonalves Teixeira Maurício Veloso Brun 《Veterinary surgery : VS》2019,48(Z1):O74-O82
8.
Wiebke Kämper Patrizia K. Werner Andrea Hilpert Catrin Westphal Nico Blüthgen Thomas Eltz Sara Diana Leonhardt 《Landscape Ecology》2016,31(10):2245-2258
Context
Abundance and diversity of bumblebees have been declining over the past decades. To successfully conserve bumblebee populations, we need to understand how landscape characteristics affect the quantity and quality of floral resources collected by colonies and subsequently colony performance.Objectives
We therefore investigated how amount and composition of pollen collected by buff-tailed bumblebee Bombus terrestris colonies was affected by the surrounding landscape (i.e. the proportion of forest, urban, semi-natural habitats) and how they were related to colony growth.Methods
Thirty B. terrestris colonies were placed at grassland sites differing in surrounding landscape. Colonies were established in spring when availability of flowering plants was highest, and their weight gain was monitored for 1 month. We additionally recorded the quantity and compared plant taxonomic composition and nutritional quality (i.e. amino acid composition) of pollen stored.Results
Bumblebee colonies varied little in the pollen spectra collected despite differences in surrounding landscape composition. They collected on average 80 % of pollen from woody plants, with 34 % belonging to the genus Acer. Early colony growth positively correlated with total amount of woody pollen and protein collected and decreased with increasing proportions of semi-natural habitats and total amino acid concentrations.Conclusions
Our results suggest that woody plant species represent highly important pollen sources for the generalist forager B. terrestris early in the season. We further show that colony growth of B. terrestris is predominantly affected by the quantity, not quality, of forage, indicating that several abundant plant species flowering throughout the bumblebees’ foraging season may cover the colonies’ nutritional needs.9.
Neff Felix Blüthgen Nico Chisté Melanie N. Simons Nadja K. Steckel Juliane Weisser Wolfgang W. Westphal Catrin Pellissier Loïc Gossner Martin M. 《Landscape Ecology》2019,34(8):2001-2015
Landscape Ecology - Insect herbivores comprise the majority of macroinvertebrate communities of temperate grasslands and act as drivers for important ecosystem functions. Landscape- and local-level... 相似文献
10.
J. Schittenhelm S. Westphal Susanne Toder E. Wagner 《Forstwissenschaftliches Centralblatt》1993,112(1):240-250
Die Auswirkungen verschiedener Stre?faktoren auf das antioxidative System wurden in sechsj?hrigen Klonfichten untersucht.
überflutung und Dunkelheit hatten nur geringen Einflu?. Im Gegensatz dazu wirkten sich die Stre?faktoren Trockenheit, K?lte,
Starklicht und sehr hohe Ozonkonzentrationen stark auf das antioxidative System aus. Die Effekte waren jedoch nicht einheitlich,
sondern waren je nach Stre?faktor unterschiedlich. Dies wird als ein Hinweis dafür gewertet, da? die Sch?den bei diesen Stre?faktoren
durch unterschiedliche toxische Sauerstoffspezies entstehen und da? sich die Sch?den unter Freilandbedingungen synergistisch
verst?rken k?nnen.
The effects of different stress factors on the antioxidative system of 6-year-old Norway spruces of the same clone were examined.
Flooding and permanent darkness had only minor effects. On the other hand drought, chilling, intense light, and very high
ozone concentrations showed strong but distinct consequences. This indicates that the damages by these stress factors are
due to different toxic oxygen species, and that the stress factors could produce synergistic damages under natural field conditions. 相似文献