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排序方式: 共有166条查询结果,搜索用时 15 毫秒
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Daniel Thiel Juergen Kreyling Sabrina Backhaus Carl Beierkuhnlein Constanze Buhk Kolja Egen Gerhard Huber Monika Konnert Laura Nagy Anke Jentsch 《European Journal of Forest Research》2014,133(2):247-260
Climate extremes are expected to increase in frequency and magnitude as a consequence of global warming, threatening the functioning, services and goods of forest ecosystems. Across Europe, the ecologically and economically important tree species Fagus sylvatica is expected to suffer particularly under such conditions. The regional introduction of provenances from drier and warmer climates is one option to adapt beech forest ecosystems to these adverse effects of climate change. Marginal populations from the drought-prone southern and north-eastern edges of the species’ distribution come into focus in search of suitable candidates for Central European deciduous forests. Here, we test three marginal provenances (Spain, Bulgaria and Poland) and three provenances from the centre of the distribution range (Germany) for their response to drought in two different soil types (sand, loam) in a full factorial common garden experiment in Landau, Germany. Drought impacted all growth parameters negatively (leaf damage +22 % (percentage points), height ?40 % and diameter increment ?41 %), and the sandy substrate exacerbated this effect. However, provenances differed in their response to drought and soil type. Evidence for a local adaptation to summer drought was detected, especially in terms of mortality rates. The Bulgarian and Spanish provenance showed a stable performance under drought conditions (BG ?27 % in diameter increment; ES ?32 %), compared to the Polish (?48 %) or the most sensitive German provenances (?57 %), yet for Bulgaria on a low level of total increment. This may indicate a trade-off between drought tolerance and growth. Therefore, a sole focus on drought-resistant marginal provenances seems to not be conducive, as they might be less adapted to other climatic factors, e.g. frost, as well. However, intermixed with local Central European provenances, these may act as functional insurance in future drought-prone forest stands. 相似文献
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Foot-and-mouth disease (FMD) is endemic in many parts of the world and poses a permanent threat for cloven-hoofed animals in all countries. The available vaccines against FMD are safe and efficacious. Combat of FMD by vaccination is controversial in currently FMD-free countries including the ones of the European Union. The article summarizes our knowledge concerning production and use of vaccines, virus persistence, differentiation between vaccinated and infected animals, vaccination programs and perspectives of vaccine development. 相似文献
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Pericardiocentesis and principles of echocardiographic imaging in the patient with cardiac neoplasia
Ultrasonography is a safe, noninvasive, sensitive, and specific tool for evaluation of the heart and pericardium in patients with cardiac neoplasia. In small animals, the incidence of cardiac neoplasia is low. In dogs, hemangiosarcoma and chemocdectoma are the two most common types of cardiac neoplasia. In cats, lymphosarcoma is the most common form of cardiac neoplasia. Pericardial effusion is a common and potentially life-threatening consequence of cardiac neoplasia. Pericardial effusion leads to a rise in the intrapericardial pressure, resulting in varying degrees of hemodynamic compromise. Cardiac tamponade occurs when the intrapericardial pressure equals or exceeds right ventricular diastolic filling pressures, leading to a decreased cardiac output. Pericardiocentesis is used to stabilize animals with life-threatening cardiac tamponade, and to obtain fluid samples for diagnostic evaluation. The fluid should be quantified and characterized. If the etiology of the effusion is not known, then a sample of the fluid should be submitted for fluid analysis and cytology. Serious complications associated with pericardiocentesis are rare. Complications include cardiac puncture, arrhythmias, and laceration of the tumor or coronary artery, resulting in intrapericardial hemorrhage. 相似文献
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Valeria Hidalgo-Ruz Guillermo Luna-Jorquera Marcus Eriksen Hanna Frick Diego Miranda-Urbina Matias Portflitt-Toro Marcelo M. Rivadeneira Christopher J.R. Robertson R. Paul Scofield Juan Serratosa Cristián G. Suazo Martin Thiel 《水产资源保护:海洋与淡水生态系统》2021,31(2):389-407
- While floating near the sea surface plastic debris interacts with a number of external factors, including many different organisms. Seabirds have the most extensive documented history of interactions with plastics, through ingestion, entanglement, and nest construction.
- In the present study, eight seabird species from the South Pacific Ocean were used as a proxy to determine potential patterns of removal of marine plastic debris, and three hypotheses were tested in relation to their feeding habits and nesting areas.
- Plastics from abiotic compartments (Chilean continental coast, South Pacific Gyre, and Rapa Nui beaches) and biotic compartments (surface-feeding seabirds, diving seabirds, and nesting areas) were compared, according to their type, colour, shape, and density.
- Continental beaches had a relatively wide range of colours and shapes, with many non-buoyant plastics. Samples from the South Pacific Gyre (SPG) and Rapa Nui (Easter Island) beaches comprised mainly hard, rounded, buoyant, and white/grey plastics.
- These results indicate that the composition of floating plastics from terrestrial sources changes during transport with oceanic currents, reducing the proportion of prey-like plastics present in the subtropical gyres.
- The stomach contents of surface-feeding and diving seabirds were dominated by hard, white/grey, and round plastic items, similar to plastics from the SPG, suggesting non-selective (accidental or secondary) ingestion.
- Nesting areas had a more variable composition of brightly coloured plastics, suggesting a pattern of selective removal of plastics by seabirds, probably from oceanic sources.
- The present study reveals extensive interactions of seabirds with plastics on a broader scale, which is highly relevant given that the impacts of plastics on seabirds are increasing worldwide, compromising their efficient conservation.
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David J. Wise Menghe H. Li Matt J. Griffin Edwin H. Robinson Lester H. Khoo Terrence E. Greenway Todd S. Byars Josh R. Walker Charles C. Mischke 《Journal of the World Aquaculture Society》2013,44(4):557-564
Bolbophorus damnificus was recognized as a threat to channel catfish, Ictalurus punctatus, production in Louisiana and Mississippi in 1997 and 1999, respectively. Severe to moderate outbreaks (≥34% prevalence) are correlated to heavy losses, but impact of mild outbreaks with low prevalence (<33%) was unknown. Laboratory and field studies were conducted to evaluate sublethal acute (early stage) and chronic (late stage) trematode infection impacts on catfish production. Fish raised in ponds seeded with ram's horn snails from ponds harboring active B. damnificus outbreaks resulted in infection prevalence ranging from 1.6 to 20.4%. Compared to fish raised in ponds not seeded with infected snails (0% prevalence), fish biomass, number harvested, and total feed fed were significantly lower. These data agree with previous studies where mild infections reduced feed consumption, fish production, and economic returns. Infected fish were collected from ponds and used in a laboratory growth study. Once removed from the infection source, weight gain, growth rate, feed consumption, and feed efficiency were equal to or greater than trematode‐free fish. This suggests that although early B. damnificus infection (premetacercarial development) can severely impact production, infection has little impact on performance once metacercarial cysts are fully developed, and the infection source is removed. 相似文献
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Isolation and purification of moniliformin 总被引:4,自引:0,他引:4
M Steyn P G Thiel G C van Schalkwyk 《Journal of the Association of Official Analytical Chemists》1978,61(3):578-580
A bulk purification procedure is described for moniliformin, a mycotoxin produced by Fusarium moniliforme. The method involves methanol extraction of suitably molded maize, aqueous extraction of the methanol-free residue, ion exchange chromatography with a NaCl concentration gradient, desalination, and crystallization. A pKa value of 1.70 as well as molar absorptivities of 19100 (lambda (H2O) max 229 nm), 5600 (lambda (H2O) max 260 nm), and 4700 (lambda (MeOH) max 260 nm) L/mole/cm are reported for moniliformin. 相似文献
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