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排序方式: 共有384条查询结果,搜索用时 609 毫秒
291.
Jay Ram Lamichhane Birol Akbas Claus Bo Andreasen Wilma Arendse Sylvia Bluemel Silke Dachbrodt-Saaydeh 《国际虫害防治杂志》2018,64(4):352-358
Recent years have seen an increasing effort towards the development and adoption of sustainable crop protection strategies, especially in the EU. Several policy frameworks have been put in place including the EU framework Directive (128/EC/2009) on the sustainable use of pesticides. Consequently, all EU Member States developed National Action Plans to ensure the implementation of the general principles of Integrated Pest Management (IPM) by all professional pesticide users starting from January 1, 2014. On the other hand, there are also difficulties related to the adoption of IPM in Europe and worldwide which seek for a better understanding of factors hindering IPM uptake. This paper presents the potential role that each actor of the food chain may have – called here stakeholders – to ensure a higher level IPM adoption in Europe. The information reported here is a summary based on several discussions held within a three-year European Research Area Network project on Coordinated Integrated Pest Management (ERA-Net C-IPM; http://c-ipm.org/). 相似文献
292.
Susan M. Newell DVM MS John P. Graham MVB MSc Gregory D. Roberts DVM MS Pamela E. Ginn DVM Jay M. Harrison MS 《Veterinary radiology & ultrasound》1999,40(1):40-43
The normal sonographic appearance of the stomach in various degrees of distension, the duodenum, the small intestine, and the large intestine was determined in awake and sedated cats. The mean stomach rugal fold thickness was 4.38 mm, and the interrugal thickness was 2.03 mm. No significant difference in stomach wall thickness was seen when the stomach was empty, half full, or full. The duodenal wall thickness was significantly greater than other parts of the small intestine, and this difference was accentuated by sedation (awake mean 2.4 mm; sedated mean 2.71 mm). The mean small intestinal wall thickness was 2.1 mm, and the mean colonic wall thickness was 1.67 mm. The five characteristic sonographic layers similar to that seen in the gastrointestinal tract of other species were routinely identified at all regions of the feline gastrointestinal tract. 相似文献
293.
Habitat use, growth, and mortality of post-settlement lane snapper (Lutjanus synagris) on natural banks in the northwestern Gulf of Mexico 总被引:1,自引:0,他引:1
Three low-relief banks in the northwestern Gulf of Mexico were evaluated as nursery habitat of lane snapper (Lutjanus synagris). Trawl surveys were conducted in three habitat types (inshore mud, shell ridge, offshore mud) to quantify lane snapper distribution and abundance. Heald Bank and Sabine Bank were trawled in 2003 while Freeport Rocks was trawled in 2000 (Freeport A) and 2004 (Freeport B). Density of lane snapper varied among banks and years sampled: Sabine Bank (20.8 ± 2.8 ind ha−1), Heald Bank (1.1 ± 0.4 ind ha−1), Freeport A (12.7 ± 2.3 ind ha−1), and Freeport B (3.0 ± 1.0 ind ha−1). Habitat-specific differences in density were observed, although patterns were not consistent among banks. Otolith microstructure analysis indicated that post-settlement lane snapper ranged in age from 21 to 66 d, with hatch dates from 1 May to 31 August. Growth rates varied from 0.90 mm d−1 at Heald Bank to 1.27 mm d−1 at Sabine Bank, and habitat-specific differences in growth were negligible. Mortality of post-settlement lane snapper ranged from 15.2% d−1 at Sabine Bank to 9.2% d−1 at Freeport A. Our findings indicate that Heald Bank, Sabine Bank, and Freeport Rocks all serve as settlement habitat of lane snapper, which appear to be capable of successful settlement across a variety of habitats. 相似文献
294.
加氧灌溉对菠萝根区土壤呼吸和生理特性的影响 总被引:5,自引:0,他引:5
通过大田试验,研究了加氧灌溉对菠萝根区土壤呼吸作用、生理特性、生物量积累、果实产量、品质和水分利用效率的影响.采用Mazeei(空气注射器)给地下灌溉系统加入空气,设计了加氧和不加氧灌溉2种处理方式,7次重复.设计滴头埋深10 cm.研究表明,与对照相比,菠萝根区30 cm以内土壤水分质量分数和CO2质量分数没有明显差异,但是加氧灌溉使得土壤呼吸增加了100%;菠萝的果实鲜重、生物量鲜重、干物质重和收获指数明显增大,差异有统计学意义(p≤0.05);加氧灌溉提高了菠萝的水分生产率,与对照相比增加了17.2%;同时,加氧灌溉明显改善了菠萝单果尺寸和重量,使得单果重量增加了17.3%,田间产量增加了4.3%,增加了果实的糖质量分数,减少了果实的透明物.研究结果为加氧灌溉技术的推广应用提供了理论依据. 相似文献
295.
Starches from eight soft wheat samples (two parent lines and six offspring) were isolated; relationships between their structures and properties were examined. Branch chain‐length distributions of amylopectins were determined by using high‐performance anion exchange chromatography equipped with an amyloglucosidase reactor and a pulsed amperometric detector (HPAEC‐ENZ‐PAD). Results showed that the average chain length of the eight samples varied at DP 25.6–26.9. Starch samples of lines 02, 60, 63, 95, and 114 consisted of amylopectins with more long chains (DP ≥ 37) and longer average chain length (DP 26.2–26.9) than that of other samples. These starch samples of longer branch chain length displayed higher gelatinization temperatures (55.3–56.5°C) than that of other samples (54.4–54.9°C) and higher peak viscosity (110–131 RVU) and lower pasting temperature (86.3–87.6°C) than others (83–100 RVU and 88.2–88.9°C, respectively). The Mw of amylopectins, determined by using high‐performance size exclusion chromatography equipped with multiangle laser‐light scattering and refractive index detectors (HPSEC‐MALLS‐RI), were similar for all samples (6.17 × 108 to 6.97 × 108). There were no significant differences in amylose and phosphorus contents between samples. These results indicated that physical properties of wheat starch were affected by the branch‐chain length of amylopectin. 相似文献
296.
297.
Impact of Cuscuta australis infection on the photosynthesis of the invasive host,Mikania micrantha,under drought condition
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Quang‐Vuong Le Kushan U. Tennakoon Faizah Metali Linda B.L. Lim Jay F. Bolin 《Weed Biology and Management》2015,15(4):138-146
Cuscuta species (dodders) are widespread stem holoparasites that depend on host plants for their entire mineral and water and most carbohydrate requirements. Dodders negatively affect host photosynthesis but precise information on their impact on hosts in the presence of environmental stress factors (i.e. drought) is little known. In a pot experiment, the leaf traits, gas exchange and chlorophyll a fluorescence of the invasive climber, Mikania micrantha, parasitized by Cuscuta australis, were investigated in order to study variations of host photosynthesis in response to parasitism and drought. The results showed that the concomitant presence of C. australis infection and drought significantly impacted the leaf traits (i.e. increased leaf dry mass content), gas exchange (i.e. decreased stomatal conductance and transpiration rates and increased water‐use efficiency) and quantum yield of chlorophyll a fluorescence of M. micrantha. The presence of a single stress factor (C. australis infection or drought), however, only significantly affected the leaf traits and gas exchange of M. micrantha. These results suggested that the combined additive effects of C. australis parasitism and drought significantly suppressed the photosynthesis of M. micrantha in relation to both stomatal and non‐stomatal limitation of host photosynthesis. This study provides insights into Cuscuta–host interactions under drought conditions in the tropics. 相似文献
298.
299.
If Arctic charr Salvelinus alpinus is ‘the most diverse vertebrate’, what is the lake charr Salvelinus namaycush?
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Andrew Michael Muir Michael Jay Hansen Charles Richard Bronte Charles Conrad Krueger 《Fish and Fisheries》2016,17(4):1194-1207
Teleost fishes are prominent vertebrate models of evolution, illustrated among old‐world radiations by the Cichlidae of East African Great Lakes and new‐world radiations by the circumpolar Arctic charr Salvelinus alpinus. Herein, we describe variation in lake charr S. namaycush morphology, life history, physiology and ecology, as another example of radiation. The lake charr is restricted to northern North America, where it originated from glacial refugia and diversified in large lakes. Shallow and deepwater morphs arose in multiple lakes, with a large‐bodied shallow‐water ‘lean’ morph in shallow inshore depths, a small‐bodied mid‐water ‘humper’ morph on offshore shoals or banks, a robust, large‐bodied moderate to deep‐water ‘redfin’; morph and a large‐bodied deep‐water ‘siscowet’ morph at depths > 100 m. Eye position, gape size, and gillraker length and spacing adapted for feeding on different‐sized prey, with piscivorous morphs (leans, siscowets and presumably redfins) reaching larger asymptotic size than invertivorous morphs (humpers). Lean morphs are light in colour, whereas deepwater morphs are drab and dark, although the pattern is reversed in dark tannic lakes. Morphs shift from benthic to pelagic feeding at a length of 400–490 mm. Phenotypic differences in locomotion, buoyancy and lipid metabolism evolved into different mechanisms for buoyancy regulation, with lean morphs relying on hydrodynamic lift and siscowet morphs relying on hydrostatic lift. We suggest that the Salvelinus genus, rather than the species S. alpinus, is a diverse genus that should be the subject of comparative studies of processes causing divergence and adaptation among member species that may lead to a more complete evolutionary conceptual model. 相似文献
300.