全文获取类型
收费全文 | 101篇 |
免费 | 0篇 |
专业分类
林业 | 11篇 |
农学 | 2篇 |
基础科学 | 3篇 |
34篇 | |
综合类 | 5篇 |
农作物 | 2篇 |
水产渔业 | 1篇 |
畜牧兽医 | 27篇 |
园艺 | 10篇 |
植物保护 | 6篇 |
出版年
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 3篇 |
2012年 | 7篇 |
2011年 | 5篇 |
2010年 | 3篇 |
2009年 | 10篇 |
2008年 | 13篇 |
2007年 | 9篇 |
2006年 | 7篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1995年 | 1篇 |
1992年 | 3篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1984年 | 1篇 |
1981年 | 2篇 |
1978年 | 1篇 |
排序方式: 共有101条查询结果,搜索用时 265 毫秒
31.
Bacteria such as Pantoea agglomerans (Pa-AF2), Bacillus subtilis (Bs-271), Acinetobacter lwoffii (Al-113), and Pseudomonas fluorescens (Pf-CT2), originating from the vineyard, can induce defense responses and enhance resistance of grapevine against the fungal pathogen Botrytis cinerea. The perception of these bacteria by plant cells or tissues in relation to their activities remains unknown. In this study, we examined the relationships between the activity of each bacterium to induce or prime some defense responses, and its effectiveness to induce resistance in grapevine against B. cinerea. We showed that all selected bacteria are capable of inducing early oxidative burst and phytoalexin (trans-resveratrol and trans-ε-viniferin) production in grapevine cells and leaves. Pf-CT2 and Al-113 induced higher H(2)O(2) and trans-resveratrol accumulations, and were able to further prime plants for accelerated phytoalexin production after B. cinerea challenge. These two bacteria were also the most effective in inducing local and systemic resistance. A similar level of induced resistance was observed with live Pa-AF2 which also induced but not primed a greater accumulation of trans-resveratrol. However, Bs-271, which was less effective in inducing resistance, induced a lower trans-resveratrol synthesis, without priming activity. Treatment of grapevine cells with growing medium or crude extract of the bacteria quickly and strongly enhanced oxidative burst compared with the live bacteria. However, both treatments resulted in comparable amounts of phytoalexins and induced local and systemic resistance to B. cinerea as compared with those induced by living bacteria, with extracts from Pf-CT2 and Al-113 being the most effective. Together, these results indicate that induced resistance can be improved by treatment with bacteria or derived compounds which induced or primed plants for enhanced phytoalexin accumulation. 相似文献
32.
Enzymatic hydrolysis as a means of expanding the cold gelation conditions of soy proteins 总被引:1,自引:0,他引:1
Kuipers BJ van Koningsveld GA Alting AC Driehuis F Gruppen H Voragen AG 《Journal of agricultural and food chemistry》2005,53(4):1031-1038
Acid-induced cold gelation of soy protein hydrolysates was studied. Hydrolysates with degrees of hydrolysis (DH) of up to 10% were prepared by using subtilisin Carlsberg. The enzyme was inhibited to uncouple the hydrolysis from the subsequent gelation; the latter was induced by the addition of glucono-delta-lactone. Visual observations, confocal scanning laser microscopy images, and the elasticity modulus showed that hydrolysates gelled at higher pH values with increasing DH. The nonhydrolyzed soy protein isolate gelled at pH approximately 6.0, whereas a DH = 5% hydrolysate gelled at pH approximately 7.6. Gels made from hydrolysates had a softer texture when manually disrupted and showed syneresis below a pH of 5-5.5. Monitoring of gelation by measuring the development of the storage modulus could be replaced by measuring the pH onset of aggregate formation (pH(Aggr-onset)) using turbidity measurements. The rate of acidification was observed to also influence this pH(Aggr-onset). Changes in ionic strength (0.03, 0.2, and 0.5 M) had only a minor influence on the pH(Aggr-onset), indicating that the aggregation is not simply a balance between repulsive electrostatic and attractive hydrophobic interactions, but is much more complex. 相似文献
33.
Jing XIANG Van Ryan HADEN Shaobing PENG Bas A. M. BOUMAN Romeo M. VISPERAS Lixiao NIE Jianliang HUANG Kehui CUI 《Soil Science and Plant Nutrition》2009,55(5):705-714
A yield decline and increase in soil pH under continuous cropping of aerobic rice have been reported in previous studies. However, the underlying mechanisms governing the poor growth and low yield of aerobic rice following an increase in soil pH are unknown. The objective of the present study was to determine the effect of soil acidification on the soil nutrient availability, plant nutrition and growth of aerobic rice grown in continuously cropped aerobic soil. Two pot experiments were conducted using soil from a field where aerobic rice had been grown for 13 consecutive seasons. Soil was acidified by adding 50–300 mL of 0.05 mol L–1 sulfuric acid to 3.0 kg of air-dried soil to achieve a range of soil pH levels. Rice was grown aerobically with N rates of 0–1.2 g per pot using urea or ammonium sulfate. Soil chemical properties were measured as were leaf nutrient concentrations, plant growth parameters, and the above-ground N uptake. A 5.5-fold and 1.5-fold increase in soil ammonium and nitrate were observed, respectively, after adding sulfuric acid. Plant growth and N uptake improved significantly with soil acidification, regardless of N rates or N sources, and were associated with an improvement in plant N nutrition. The application of N had greater positive effects on plant growth and N uptake than soil acidification. The growth response to soil acidification reduced as the rate of N application increased. These results suggest that the yield decline of continuous aerobic rice is probably associated with a reduction in soil N availability and plant N uptake as a result of a gradual increase in soil pH. 相似文献
34.
35.
The effects of historical land use changes on the global C cycle have mainly been studied by means of bookkeeping models. Here, we investigate with such models the impact of afforestation and deforestation on soil organic carbon (SOC) stocks. This approach, using field-based estimates of the response of SOC upon land use changes, is applied to a pilot area in the Belgian Ardennes over one and a half century (1868–2005). After a small initial decline during the 1868–1888 period due to deforestation for agricultural use, mean SOC stocks increased steadily up to 1990, due essentially to the conversion of deciduous to coniferous forests (in the study area, deciduous forests stored less SOC than coniferous) and the reclamation of heathland, which occurred both at the turn of the 19th and 20th centuries. Simulations showed that SOC stocks decreased recently (1990–2005) because of the slow down of sequestration in coniferous forests and a reversion of some of the coniferous plantations to deciduous forests. Over the entire period, afforestation resulted in a net sequestration of carbon (0.16 t C ha−1 year−1). Monte Carlo simulations demonstrated that the model was highly sensitive to its inputs (initial SOC stocks for each land use) both in term of predicted SOC stocks and rates of SOC stocks change. However, the sensitivity of the model was not large enough to revert the main trends of SOC changes observed. Compared to the amount of carbon sequestered in the biomass, the contribution of soils to the C sink in forest is small. Despite several sources of errors, a detailed reconstruction of land use changes combined with realistic SOC response curves upon land use conversion are required to be able to quantify the contribution of soils to terrestrial carbon fluxes. 相似文献
36.
Suzanna Lettens Jos Van Orshoven Dominique Perrtn Bas Van Wesemael Bart Muys 《Annals of Forest Science》2008,65(6):604-604
37.
Nowadays European agriculture is evolving in a context where policy-making and environmental concerns play a key role. To better assess agro-environmental policies, the AROPAj agricultural supply model needs to take into account the technical characteristics of crop management for different farms. A method to build up specific relationships between yield and nitrogen fertilization that takes into account agronomic techniques is proposed in this paper. The nitrogen response curve is based on an exponential function that integrates economic properties consistently from an agronomic point of view. In AROPAj, individual production systems (farm types) do not have a given location within a specified region and in databases technical information is scarce. The method involves determining technical and physical characteristics, inputs that allow the STICS crop model to assess the yield response to nitrogen of each crop on every farm type. From this information, a nitrogen response curve can be drawn up for each crop of each one of the farms. It can take into account both nitrogen from purchased fertilizer and nitrogen from animal effluents produced on farm. The method was designed to be adaptable to any European region, and tests carried out on two French regions covering a wide range of situations (crops, soils, climates and techniques) showed it was able to cope with varying prices and environments. The agronomic consistency of STICS inputs and curve shapes was also checked. When incorporated into the AROPAj economic model, the response curves can be used to render farms more sensitive to agricultural policy scenarios, by allowing their optimal fertilization level to be adjusted. 相似文献
38.
Hüseyin Basım Esin Basım Derya Baki Muntala Abdulai Nurhan Öztürk Recep Balkic 《European journal of plant pathology / European Foundation for Plant Pathology》2018,150(1):73-90
A new dagger nematode, Xiphinema tica n. sp., is described and illustrated from several populations extracted from soil associated with several crops and wild plants in Costa Rica. The new dagger nematode is characterised by a moderate body size (3276–4240 μm), a rounded lip region, ca 13.5 μm wide, separated from body contour by a shallow depression, amphidial fovea large, stirrup-shaped, a moderately long odontostyle ca 135 μm long, stylet guiding ring located at ca 122 μm from anterior end, vulva almost equatorial (50–54%), well-developed Z-organ, with heavy muscularised wall containing in the most of specimens observed two moderately refractive inclusions variable in shape (from round to star-shaped), with uterine spines and crystalloid bodies; female tail short, dorsally convex-conoid, with rounded end and a small peg, with a c’ ratio ca 0.8, bearing two or three pairs of caudal pores and male absent. The unique and novel uterine differentiation based on the coexistence of a well-developed Z-organ mixed with uterine spines and crystalloid bodies in Xiphinema prompted us to update and include this combination of characters in the polytomous key of Loof and Luc (1990). Integrative diagnosis was completed with molecular data obtained, using D2-D3 expansion segments of 28S rDNA, ITS1-rDNA, partial 18S–rDNA and the partial mitochondrial gene cytochrome c oxidase subunit 1 (coxI). The phylogenetic relationships of this species with other Xiphinema spp. indicated that X. tica n. sp. was monophyletic to the other species from the morphospecies Group 4, Xiphinema oleae. 相似文献
39.
Kwame Antwi Oduro Bas Arts Boateng Kyereh Godefridus Mohren 《Small-Scale Forestry》2018,17(3):393-410
Deforestation and forest degradation, especially in the agricultural landscapes, are serious threats to biodiversity conservation and sustainability of the timber industry. Planting trees on farms has been identified as having great potential to increase forest resources from agricultural landscapes. This paper examined farmers’ motivations and behaviour to engage in on-farm tree planting and management in Ghana by combining internal and external factors in a socio-psychological model. Data were collected from 156 smallholder farmers from five communities in two forest districts using a semi-structured questionnaire. Additional farm inventory data were collected from 33 farmers under two on-farm tree planting schemes. On-farm tree planting was perceived as providing income, access to personal timber for furniture, and access to loan facilities. Incentives such as provision of grants, farming inputs, capacity training, and access to markets for agricultural produce are factors that motivate on-farm tree planting in Ghana. The average standing volume of on-farm trees in the study area is 51.9 m3/ha which is almost twice the national average for the off-reserve areas in the semi-deciduous forests to which much of the study sites belong. Many farmers considered high financial costs and limited knowledge of appropriate techniques in managing planted on-farm trees as barriers to the development of tree stock on farms. 相似文献
40.
Perennial kale is a rare leafy vegetable and forage crop that is mainly vegetatively propagated and therefore expensive to
conserve ex situ. A genebank collection of 47 perennial kales and 34 reference samples from the main Brassica oleracea crop types were characterized with seven microsatellite markers in order to verify potential redundancies and to obtain more
insight in the position of perennial kales within B. oleracea. Based on the obtained results and on data from previous studies, the collection was reduced with 49% to 24 perennial kales.
Considering this level of reduction, it was estimated that the investments made for the final verification by microsatellite
analysis are returned after only 4-year time. A principal coordinate plot clearly separated the perennial kales from the other
crop types of B. oleracea, except in one case. This deviating accession of vegetatively preserved perennial kale clustered closely together with the
single seed-preserved accession of perennial kale included in the study. These two accessions occupied an intermediate position
between the group of vegetatively propagated perennial kales and the group of seed-propagated Brassica accessions, suggesting a hybridization background with another B. oleracea crop type. The microsatellite study demonstrated a close genetic relationship among the investigated perennial kales and
their unique position within B. oleracea. 相似文献