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41.
The dependences between negative charge and pH for organic matter of limed and unlimed profiles of sandy acidic forest soils were determined on the base of ion exchange and titration curves measurements. Subtracting the titration curves of the supernatant from the titration curves of the respective suspensions the quantities of base consumed by solid phases were determined. They were interpreted in terms of negative charge after corrections with the quantities of initial exchangeable basic cations and exchangeable hydrogen. For investigated organic material the charge increased slowly in acidic pH region and much faster in alkaline pH region. The zones of the fast increase of charge occured at higher pH's for deeper horizons, enriched with fulvic acids. The observed changes of organic matter charge due to liming were related to the increase of fulvic to humic acids ratio. The negative charges of organic matter in limed and unlimed profiles estimated for high pH were better correlated with fulvic to humic acids ratio than when estimated for lower pH levels.  相似文献   
42.
The main results of the International Co-operative Programme on Effects on Materials, including Historic and Cultural Monuments (ICP Materials) within the United Nations Economic Commission for Europe (UN ECE) are summarised. The 8-year field exposure programme involves 39 test sites in 12 European countries and in the United States and Canada. Dose-response functions (DRF) expressing the effect of dry and wet deposition as individual terms have been obtained for a wide range of materials including bronze, copper, weathering steel, zinc, aluminium, nickel, tin, stone materials, paint coatings and glass materials. The DRF's includes parameters that are easily available on different geographical scales and can be used for mapping areas of increased corrosion rates and for calculation of costs.  相似文献   
43.
Beer contains a very complex mixture of nutrients, which in this work are identified to some extent by high-field high-resolution nuclear magnetic resonance (NMR) one- and two-dimensional methods. The (1)H NMR spectrum of beer shows a predominance of strongly overlapped peaks arising from several carbohydrates. Minor components are clearly observed both in the aliphatic and in the aromatic regions of the spectrum. With the aid of two-dimensional methods, spectral assignment was carried out, enabling the identification of approximately 30 compounds and identifying about the same number of spin systems for further assignment. The variability of the spectral profile of beers differing in type and label was studied by principal component analysis (PCA), and it was found that, although some distinction is achieved on the basis of the aliphatic and sugar compositions, clearer separation between ales and lagers is obtained by PCA of the aromatic profiles alone. The potential of this technique as a rapid and informative quality control tool is discussed.  相似文献   
44.
45.
Repräsentative ostdeutsche Landwirtschaftsbetriebe sind hinsichtlich ihrer Umweltverträglichkeit bewertet worden. Dazu diente eine Methode, die für ca. 30 relevante Umwelt‐Gefährdungspotentiale aus den Bereichen Düngung, Bodenschutz, Pflanzenschutzmitteleinsatz, Agrarraumgestaltung, Artendiversität, Energiebilanz und Tierbesatz kritische Umweltbelastungen formuliert und damit aktuelle Betriebsdaten wertend vergleicht.

Die Ergebnisse zeigen eine sehr differenzierte Situation. Während Stoffbelastungen mit Konsequenzen für die Nahrungsqualität weitgehend unkritisch sind, bestehen Defizite vor allem als “Altlasten”; in den Bereichen Bodenschutz und Agrarraumgestaltung.

Beziehungen zwischen Intensität und Umweltverträglichkeitsbewertung werden diskutiert.  相似文献   
46.
Soil compaction affects physical soil condition, in particular aeration, soil strength, and water availability and has adverse effects on plant growth. Bulk density is the most frequently used indicator to describe the state of compaction of a soil. However, this parameter lacks a direct functional relationship with plant growth. Various indicators have been proposed to simultaneously characterize the state of compaction of agricultural soil and its suitability for plant growth. This paper examines and compares the critical limits for crop plant growth based on three of these indicators: packing density, least limiting water range, and S parameter (the latter is the slope of the soil water‐retention curve in the inflexion point). In a first step, we reviewed the literature for published optimum and limiting values of bulk density and found that these values were highly dependent on clay and silt content. Converting them into corresponding values of packing density (composite index of bulk density and clay content), a value of 1.70 was found to effectively distinguish between optimum and limiting soil conditions for plant growth. In a second step, the packing density of 59 soil horizons sampled in N Switzerland was compared with the least limiting water range and the S parameter of these soil horizons (both determined by means of pedotransfer functions taken from the literature). A linear relationship between the three parameters was found, which allowed for a comparison of the published critical limits for plant growth based on these parameters. The critical limits of the three indicators, which had been postulated independently of each other in the literature, were found to agree well with each other. This means that all of them could equally be used to describe the compaction state of a soil and its physical suitability for plant growth. However, the proposed critical limits of packing density, least limiting water range, and S parameter still need further validation by field studies relating plant growth to soil compaction.  相似文献   
47.
Adipose tissue expresses adipokines, which are involved in regulation of energy expenditure, lipid metabolism, and insulin sensitivity. To adapt for the transition from pregnancy to lactation, particularly in high-yielding dairy cows, adipokines, their receptors, and particular G-protein coupled receptors (GPRs) are of potential importance. Signaling by GPR 41 stimulates leptin release via activation by short-chain fatty acids; GPR 43/109A inhibits lipolysis, and GPR 109A thereby mediates the lipid-lowering effects of nicotinic acid and β–hydroxybutyrate. The aim of this study was to compare the mRNA expression of adiponectin and visfatin, adiponectin receptors 1 and 2 (AdipoR1/2), leptin receptor (obRb), insulin receptor as of the aforementioned GPRs during the transition period in high-yielding dairy cows. Biopsies from subcutaneous fat and blood samples were obtained from 10 dairy cows 1 week before and 3 weeks after calving. For AdipoR1 and AdipoR2 mRNA abundance as well as for leptin concentrations in plasma, a reduction (P ≤ .05) was observed postpartum; for visfatin and putative GPR 109A mRNA abundance in adipose tissue, there was a trend (P < .1) for analogous changes. In contrast, the mRNA content of obRb and GPR 41 in adipose tissue was higher (P ≤ .05) in samples from early lactation than in those from late gestation. Our results indicate decreasing adiponectin sensitivity in adipose tissue after calving, which might be involved in the reduced insulin sensitivity of adipose tissue during early lactation. In addition, visfatin, GPR 41, and GPR 109A may further modulate insulin sensitivity.  相似文献   
48.
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   
49.
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   
50.
Quantitative and qualitative changes in soil properties of A- horizons of sandy soils caused by conversion of grassland to arable land Changes in physical soil properties and in soil organic matter of the A-horizons due to the conversion of permanent grassland to arable land are quantified and described as a function of time for sandy soils. The study was carried out in an area northeast of Hannover. A decrease of about 100 t/ha Corg (- 57%), 5 – 6 t/ha Norg (- 58%) and 1 t/ha St (- 58%) was measured for a period of 2 – 4 years after grassland conversion. Thereby the quality of the soil organic matter remains unchanged (no changes of the C/N ratio and of the distribution of Norg in 5 N-fractions). However, an increase of soil bulk density from 1.0 to 1.3 g/cm3 and a decrease of total pore volume from 0.59 to 0.47 were observed. The fast mineralization of soil organic matter in the A-horizon following the conversion of grassland soils results in a temporary heavily increased nitrate input into the groundwater. Furthermore mineralization and leaching of nitrate and sulfate induces an acidification push in the soil by a proton release in the order of 350 keq/ha during a 2 – 4 years period. However, this proton production is compensated quantitatively by several applications of lime or marl by farmers and by the buffering of bases cations released from mineralized soil organic matter.  相似文献   
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