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排序方式: 共有403条查询结果,搜索用时 15 毫秒
41.
Van Sinh Nguyen Hung Manh Nguyen Anika Klotzbücher Doris Vetterlein Thimo Klotzbücher Reinhold Jahn Janina Schneiker Manfred Türke Oliver Fried Erwin Bergmeier Cornelia Sattler Josef Settele 《Paddy and Water Environment》2018,16(2):353-358
Two major human-made problems in rice production systems in the north of Vietnam concern the low plant-available silicon content of soils and the low biodiversity. The results of the LEGATO project suggest a change to an environmentally friendly rice production system that will help to recover biodiversity. We propose here a framework for a demonstration and dissemination model that will be exemplary for the farmers once it has been successfully realized. We advocate local-option models in different districts to demonstrate to farmers. The methods should be adapted to local and ecoregional differences in climate and land-use tradition, and they explicitly take into account soil care, organic fertilizer, manual weeding, native nectar-rich plant bunds, manual pest snail collection, hymenopteran nesting aids, and biodiversity and yield monitoring. 相似文献
42.
Marine microorganisms harbor a multitude of secondary metabolites. Among these are toxins of different chemical classes as well as the UV-protective mycosporine-like amino acids (MAAs). The latter form a group of water-soluble, low molecular-weight (generally < 400) compounds composed of either an aminocyclohexenone or an aminocyclohexenimine ring, carrying amino acid or amino alcohol substituents. So far there has been no report of toxicity in MAAs but nevertheless there are some features they have in common with marine toxins. Among the organisms producing MAAs are cyanobacteria, dinoflagellates and diatoms that also synthesize toxins. As in cyclic peptide toxins found in cyanobacteria, amino acids are the main building blocks of MAAs. Both, MAAs and some marine toxins are transferred to other organisms e.g. via the food chains, and chemical modifications can take place in secondary consumers. In contrast to algal toxins, the physiological role of MAAs is clearly the protection from harmful UV radiation by physical screening. However, other roles, e.g. as osmolytes and antioxidants, are also considered. In this paper the common characteristics of MAAs and marine toxins are discussed as well as the differences. 相似文献
43.
Manfred Albertsen 《植物养料与土壤学杂志》1979,142(1):39-56
Carbon dioxide balance in the gas filled part of the unsaturated zone, demonstrated at a Podzol Carbon dioxide concentration (with a modified Miotke-probe) and moisture distribution (with a neutron-probe) in the unsaturated zone were measured on four test fields (coniferous forest, leafy wood, grass glade, sugar-beet field) in the Segeberger Forst, south of Schleswig-Holstein, Federal Republic of Germany, during September 1976 until August 1977 down to 250 cm depth. An evaluation method to calculate carbon dioxide production rates from any horizontal soil section and carbon dioxide emission rates was established and formulated in FortranIV for computer treatment. The calculation bases on Fick's diffusion laws, which describe the direct proportional relation between diffusive transport and concentration gradient with diffusivity as proportional factor. Special measurements on undisturbed soil samples from the test region showed a relation between diffusivity and the soil parameters water content and porosity, which permits the calculation of diffusivities from moisture data in any soil depth. Seasonal distribution curves of carbon dioxide concentration, production and emission are presented as evaluation result of all data. 相似文献
44.
Early pathogen detection under different water status and the assessment of spray application in vineyards through the use of thermal imagery 总被引:3,自引:0,他引:3
Manfred Stoll Hans R. Schultz Gerhard Baecker Beate Berkelmann-Loehnertz 《Precision Agriculture》2008,9(6):407-417
Remote detection using thermal imagery has potential for use in the pre-symptomatic diagnosis of abiotic stress or of early
disease detection. The latter is an issue of great importance since late detection of fungus attacks or poor spray coverage
are major factors contributing to weak disease control affecting fruit quality or reducing yield in grapes. In greenhouse
experiments the effects on spatial and temporal variability of leaf temperature of grapevine (Vitis vinifera L. cv. Riesling) leaves inoculated with a fungal pathogen (Plasmopara viticola (Berk. & Curt. Ex de Bary) were studied in either well-irrigated or non-irrigated potted plants. Due to the high sensitivity
of leaf temperature to the amount of water transpired, infra-red thermography can be used to monitor irregularities in temperature
at an early stage of pathogen development. Evidence for characteristic thermal responses in grapevines was apparent well before
visible symptoms appeared. Contrasting thermal effects due to the pathogen attack were found between measurements on well-irrigated
and water-stressed plants. Furthermore, from a technical point of view, thermal imagery has the potential to assess the evenness
of spray coverage within a canopy, hence optimizing pesticide application efficiency. 相似文献
45.
Franz Lahnsteiner Manfred Kletzl Thomas Weismann 《Aquaculture (Amsterdam, Netherlands)》2009,295(1-2):120-125
Natural zooplankton is a potential food resource for juvenile fish in fish farms as it is a good source of fats, carbohydrates, and protein. However, it is also a potential source of parasites and pathogens. The present study was conducted (1) to estimate the risk of parasite transfer by live copepod food under intensive farming conditions using the parasites Triaenophorus crassus and Triaenophorus nodulosus as example and (2) to look for strategies to avoid parasite infestation of juvenile fish.An easy and routinely applicable aniline blue staining method was developed to check the infestation levels of copepods with procercoids during the on-growing season of juvenile fish. From the copepod species occurring in zooplankton Cyclops spp. was infested frequently (9.4 ± 12.0%, maximum 38.7%), Diaptomus spp. infrequently (1.5 ± 1.6%, maximum 3.2%), Daphnia spp. never. Juvenile grayling, Thymallus thymallus, and corgonids, Coregonus sp., which had been fed with natural zooplankton revealed infestations rates with T. crassus of circa 5%, with T. nodulosus of circa 10%. As the occurrence of procercoids in the zooplankton was temporary limited, Triaenophorus infestation can be avoided by using artificial food instead of live copepods during the risky season.To prevent parasite infestation of juvenile fish methods were investigated to eradicate procercoids from copepods by chemical treatment (sodium chloride, hydrogen peroxide, citric acid treatment) and by freeze-thawing methods. Chemical methods failed to remove procercoids. In fish, which had been fed with frozen thawed zooplankton, no Triaenophorus spp. infestation was observed. Their survival rates were similar as in the control fed with live zooplankton, however the weight of the fish was significantly lower. 相似文献
46.
Like marine fish freshwater fish are an important source of essential fatty acids for human nutrition. However, the fatty
acid composition of pond fish can vary considerably and strongly depends on that of the ingested food. Investigations on the
fatty acid composition of common carp (Cyprinus carpio) and tench (Tinca tinca) have shown that different methods of rearing and feeding cause substantial variations in the proportions of the n-6 and
n-3 polyunsaturated fatty acids of these fish species. Carp reared on the basis of natural food in ponds exhibit high contents
of n-6 as well as n-3 fatty acids in their muscle triacylglycerols. On the other hand carp fed supplementary wheat in ponds
resulted in somewhat lower levels of these essential fatty acids. High amounts of n-3 fatty acids can be found in carp fed
high-energy diets containing high levels of fish oil. Analogous results were obtained in experiments with tench reared under
different nutritional conditions. While rearing on the basis of only natural food in ponds as well as feeding supplementary
wheat yielded in similar levels of n-3 and n-6 polyunsaturated fatty acids, higher contents of n-3 fatty acids were recorded
in tench fed pellets. High levels of n-3 polyunsaturated fatty acids in foodstuffs have positive effects on human health.
Experiments with different cultured fish species proved that the fatty acid composition of the edible parts can be influenced
by the diet. Therefore, a finishing diet with a suitable fatty acid profile can be used to improve the nutritional quality
of fish products of farmed origin. 相似文献
47.
Fan S Baets R Petrov A Yu Z Joannopoulos JD Freude W Melloni A Popović M Vanwolleghem M Jalas D Eich M Krause M Renner H Brinkmeyer E Doerr CR 《Science (New York, N.Y.)》2012,335(6064):38; author reply 38
We show that the structure demonstrated by Feng et al. (Reports, 5 August 2011, p. 729) cannot enable optical isolation because it possesses a symmetric scattering matrix. Moreover, one cannot construct an optical isolator by incorporating this structure into any system as long as the system is linear and time-independent and is described by materials with a scalar dielectric function. 相似文献
48.
Liu PT Stenger S Li H Wenzel L Tan BH Krutzik SR Ochoa MT Schauber J Wu K Meinken C Kamen DL Wagner M Bals R Steinmeyer A Zügel U Gallo RL Eisenberg D Hewison M Hollis BW Adams JS Bloom BR Modlin RL 《Science (New York, N.Y.)》2006,311(5768):1770-1773
In innate immune responses, activation of Toll-like receptors (TLRs) triggers direct antimicrobial activity against intracellular bacteria, which in murine, but not human, monocytes and macrophages is mediated principally by nitric oxide. We report here that TLR activation of human macrophages up-regulated expression of the vitamin D receptor and the vitamin D-1-hydroxylase genes, leading to induction of the antimicrobial peptide cathelicidin and killing of intracellular Mycobacterium tuberculosis. We also observed that sera from African-American individuals, known to have increased susceptibility to tuberculosis, had low 25-hydroxyvitamin D and were inefficient in supporting cathelicidin messenger RNA induction. These data support a link between TLRs and vitamin D-mediated innate immunity and suggest that differences in ability of human populations to produce vitamin D may contribute to susceptibility to microbial infection. 相似文献
49.
Söllner C Burghammer M Busch-Nentwich E Berger J Schwarz H Riekel C Nicolson T 《Science (New York, N.Y.)》2003,302(5643):282-286
The stone-like otoliths from the ears of teleost fishes are involved in balance and hearing and consist of calcium carbonate crystallites embedded in a protein framework. We report that a previously unknown gene, starmaker, is required in zebrafish for otolith morphogenesis. Reduction of starmaker activity by injection of modified antisense oligonucleotides causes a change in the crystal lattice structure and thus a change in otolith morphology. The expression pattern of starmaker, along with the presence of the protein on the growing otolith, suggest that the expression levels of starmaker control the shape of the otoliths. 相似文献
50.
Gelfand MJ Raver JL Nishii L Leslie LM Lun J Lim BC Duan L Almaliach A Ang S Arnadottir J Aycan Z Boehnke K Boski P Cabecinhas R Chan D Chhokar J D'Amato A Ferrer M Fischlmayr IC Fischer R Fülöp M Georgas J Kashima ES Kashima Y Kim K Lempereur A Marquez P Othman R Overlaet B Panagiotopoulou P Peltzer K Perez-Florizno LR Ponomarenko L Realo A Schei V Schmitt M Smith PB Soomro N Szabo E Taveesin N Toyama M Van de Vliert E Vohra N Ward C Yamaguchi S 《Science (New York, N.Y.)》2011,332(6033):1100-1104
With data from 33 nations, we illustrate the differences between cultures that are tight (have many strong norms and a low tolerance of deviant behavior) versus loose (have weak social norms and a high tolerance of deviant behavior). Tightness-looseness is part of a complex, loosely integrated multilevel system that comprises distal ecological and historical threats (e.g., high population density, resource scarcity, a history of territorial conflict, and disease and environmental threats), broad versus narrow socialization in societal institutions (e.g., autocracy, media regulations), the strength of everyday recurring situations, and micro-level psychological affordances (e.g., prevention self-guides, high regulatory strength, need for structure). This research advances knowledge that can foster cross-cultural understanding in a world of increasing global interdependence and has implications for modeling cultural change. 相似文献