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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.
Steffen Hoy Jrg Bauer Catrin Borberg Leonie Chonsch Carmen Weirich 《Livestock Science》2009,126(1-3):69-72
The investigations were carried out with 484 sows from two farms (farm A: housing the sows in small groups of 8 animals each, farm B with a large group of 100 sows) and a total number of 982 inseminations. The number of agonistic interactions was registered for each sow during 48 h after mixing soon after weaning the piglets at farm A. The individual rank place in the social hierarchy was calculated on the basis of wins and defeats and the sows were divided in high and low ranking sows. At farm B the rank position was estimated on the basis of the daily feeding order at two electronic feeding stations (first half of the sows in the feeding order = high ranking, second half = low ranking). Additionally, the following parameters were recorded for each sow: parity, genotype, farrowing rate and litter size (total and alive born piglets). The analysis showed that sows with a high rank position had a significantly higher farrowing rate (88.8%) compared to group-mates with low rank places (82.8%, p = 0.051) (farm A). Sows with a high rank position reached a significantly higher litter size of total born piglets (12.66, 16.14 piglets per litter respectively) than the low-ranking group-mates (12.13, 14.83 piglets/litter respectively — farms A and B). When mixing sows, the time and the conditions (e.g. group size, space allowance per sow) have to be considered to prevent the negative influence of low rank order on fertility. 相似文献
3.
Transition into higher education requires students to adjust to a new environment while showing greater independence in managing their own academic and personal life. This is often more difficult for international students who have to adjust to a different country, culture, and potentially another language. A cohort of first-year veterinary medicine students (17% international students) was investigated at a UK university using qualitative and quantitative questionnaires rating first-year experience and support services and statistical analysis of students' assessment performance. While the overall undergraduate perception was that they had learned a lot and progressed well, students in both groups struggled to cope with the workload. The non-UK educated students and students with English as a foreign language also struggled more with teaching delivery in lectures and participation in self-directed group learning and were more likely to feel that the veterinary degree program was too difficult. There was no statistical difference in how British and international students perceived the support system, although it was noticeable that the level of tutorial support was perceived as tutor-dependent. The international students particularly struggled with the assessments in early modules and also with the spot assessment method. However, in the practical assessments, using observed, structured practical exam stations, international and British students performed equally well. Increased support in the initial transition time, especially with regard to communication skills and confidence required for interactive teaching and learning environments such as small-group teaching, as well as increased time for specific assessment types, might benefit the needs of many international students. 相似文献
4.
5.
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
6.
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
7.
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
8.
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
9.
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.10.
A total number of 26 groups of 8 sows each were mixed after weaning the piglets in a special stimulation pen, including 13 groups with and 13 groups without boar presence. Behavioural measurements were taken for 48 h after mixing and all agonistic interactions (AI) were recorded into a winner–loser-matrix. Additionally, the duration of the AI and the start situation (aggressor–receiver) were determined. Also the skin lesions of each sow 24 h before and after mixing were scored. A total of 90% of the AI were initiated by the dominant sow in the concerned dyad. In more than 50% of all cases low ranking sows were attacked by higher ranking sows. Low ranking sows had a significantly higher skin lesion score than high ranking sows (9.6 vs 6.9). 12.8% of the AI were fights. Fights (mean duration: 30 s) took ten times longer than attacks. Boar presence did not affect the total number of AI per sow but decreased the number of fights to almost half (3.6 vs 6.4). Duration of fighting was shortened by boar presence (14.9 vs 39.6 s). The skin lesion score and the sociometric parameters were unaffected by treatment. Frequency of AI per group was affected by the microclimate and the number of acquainted dyads (pairs). The number of AI was reduced by a higher enthalpy and a higher number of acquainted sows, respectively. 相似文献