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991.
992.
《Communications in Soil Science and Plant Analysis》2012,43(7):619-636
Abstract Better understanding of soil aluminum has had dramatic effects on the interpretation of many aspects of soil chemistry. Aluminum is a Group III element, metallic in nature, and exhibits both ionic and cuvaient bonding. It is the most plentiful of all metallic cations of the earth's crust. It is released from octahedral coordination with oxygen in minerals by weathering processes. Once released, the trivalent Al ion assumes octahedral coordination with six OH2 groups each of which dissociates a H ion in sequence as pH increases. The resulting hydroxy‐Al ions are absorbed to the cation exchange capacity of the soil. Here they polymerize on charged surfaces and in the interlayers of the clay minerals obstructing both the contraction of the clay lattice and the exchange of cations. Soluble Al is toxic to most plants, and reacts readily with soluble phosphates converting them to relatively insoluble and plant‐unavailable forms. Adsorbed and polymerized aluminum affects actual lime requirements of soils by its acidic nature and indicated lime requirements by its effect on the buffers of the lime requirement test. The level of exchangeable Al has been suggested as an Index of lime requirement of acid soils, but this may be an adequate Index for liming only on highly weathered soils. 相似文献
993.
994.
《Wood material science & engineering》2013,8(4):353-367
AbstractWith currently used surveying methods, the on-site assembly of joinery products often consumes half the supplier budget. Due to spatial uncertainties, the manual product-to-room fitting of components is a major consumer of time and labour resources. With reliable as-built construction-site geometrical information, this fitting could be moved to the design stage early in the supplier process. In this study, the currently used manual surveying methods were compared with two different three-dimensional (3-D) sensing surveying methods, a portable wire-bound coordinate measuring machine (CMM) and a laser-scanning machine. The comparison evaluates the applicability of the on-site surveying methods and their potential for improving the current surveying process, moving the product-to-room fitting to the design stage. Results show that currently used manual surveying methods leave uncertainties regarding the dimensions of a construction site and are insufficient for moving the product-to-room fitting to the design stage. CMM surveying has the potential to supply coordinate registrations on a par with desired accuracy requirements, but it has limitations at the practically possible detailing level. Laser scanning seems to be applicable for the surveying for a joinery products supplier, but the accurate and detailed 3-D reconstruction of the point-cloud data is difficult and requires extensive processing. It can be concluded that the concept of digitized measurement of the as-built spatial dimensions of a construction site to enable product-to-room during the design stage has the potential to succeed with currently available digitizing technologies, but that some challenges remain. 相似文献
995.
996.
张丽丽 《吉林农业科技学院学报》2012,(3):115-118
吉林省主要城市及景点旅游产品与公示语翻译现状存在着许多问题,在一定程度上损害了吉林省的对外形象。通过调查找出吉林省主要城市及景点旅游产品与公示语翻译存在的主要问题,从汉英语言风格、传统习俗、思维习惯的差异及管理部门的内、外部因素等方面分析其成因,并就吉林省主要城市及景点旅游产品与公示语翻译规范性对策提出一些看法与观点。 相似文献
997.
《Journal Of Aquatic Food Product Technology》2013,22(1):33-44
Abstract Canned bighead carp has shown potential as a freshwater fish product. Canned products made from bighead carp loins that had been either cooked in steam or a convection oven were evaluated by a consumer panel of 90 individuals. The consumers were not told the identity of the fish under consideration. Acceptability was estimated by use of hedonic scales for sensory attributes, open-ended questions about how the products compared to similar canned fish products, and the just right scale for attribute direction for change. Willingness to pay compared to similar products also was determined for each product. Both carp products were light in color and contained less than 1% crude lipids. Acceptability of both products was good with the steam-cooked carp products being slightly more preferred in most categories. For the sensory attribute, “overall liking,” 54% of panelists rated the steam-cooked product as either like very much or like moderately. Likewise, over 60% of panelists indicated that either carp product was better than or equal to canned tuna and that they would be willing to pay as much for either product as tuna. 相似文献
998.
尽管国家和农业行政主管部门于近些年加大了对无公害农产品开发的政策引导和技术监管力度,但是收效不佳。为此,该文在剖析现实困境的基础上,探索促进无公害农产品开发的政策和法律措施,以实现无公害农产品开发的良性循环。 相似文献
999.
L. G. García-Montero J. L. Manjón S. Martín-Fernández G. Di Massimo 《Agroforestry Systems》2007,70(3):243-249
In Mediterranean pine forests, truffles and mushrooms generate greater profits than any other woodland products. However,
there are no studies on Tuber melanosporum Vittad. associated with pines. For this reason, we have carried out a study of this truffle in mountain woods with Pinus sylvestris L. and P. nigra Arnold subsp. salzmannii (Dunal) Franco, in central Spain. Two hundred and eight Tuber melanosporum burns were monitored for 7 years in five different habitats within the same geographical area. An ANOVA test confirmed significant
differences in carpophore production. In higher producing habitats, pines were less abundant. We also confirmed that in 433
burns, T. melanosporum was always unequivocally associated with the root base of Quercus or Corylus trees. Similarly, 14 truffle collectors confirmed that they had never found a single burn with carpophore production associated
exclusively with pines. Nevertheless, soil analyses indicated that the soil of these pine woods was very favourable to Tuber melanosporum. We therefore conclude that at present Pinus nigra
salzmannii and P. sylvestris are of little interest to Tuber melanosporum culture, as they hinder carpophore production. However, this study has also confirmed that Pinus nigra salzmannii and P. sylvestris mycorrhize easily with Tuber melanosporum, both in the laboratory and in natural environments. On this basis, we propose that pines may act as transmitters of T. melanosporum, although they do not induce fruiting. As a result, the commercial cultivation of Pinus nigra
salzmannii and P. sylvestris seedlings mycorrhized with Tuber melanosporum is not recommended in truffle culture at the present time. 相似文献
1000.
有机生态型无土栽培技术是培育蔬菜和花卉等获得无公害产品的最佳途径;它投资少,经济效益高,可推广使用。 相似文献