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991.
波纹巴非蛤肉的食品化学特性及其在鱼糜制品中的应用 总被引:5,自引:0,他引:5
对波纹巴非蛤肉进行的食品化学特性研究表明 :其贝肉的粗蛋白含量为 70 .6 % (干基 ) ;蛋白质营养价高 ,氨基酸价为 85(第 1限制氨基酸为 Trp) ,并富含 Glu(10 0 g样品中 2 .2 g;以下单位同 )、Asp(1.4 7g)等呈味氨基酸及提取物成分 ,Ca、Fe等无机质含量丰富。波纹巴非蛤肉以 30 %的比例添加到蛇鲻鱼糜中 ,可制得具有贝类风味 ,色泽、弹性良好的“花甲螺丸” 相似文献
992.
采用LI-6400-09土壤呼吸室对盘锦湿地芦苇群落土壤呼吸作用,于2004年7月—2005年12月进行连续野外观测。结果表明:非淹水状态下,湿地芦苇群落土壤呼吸作用具有明显的日变化和季节变化特征;淹水状态下,湿地芦苇群落土壤呼吸作用接近于0。2005年潮汐造成的洪水减少了2/3的土壤呼吸作用。2004年和2005年芦苇群落土壤呼吸作用最大值都出现于洪水退去后。影响湿地芦苇群落土壤呼吸作用空间异质性的主导因子是生物因子,而在同一时间影响湿地芦苇群落土壤呼吸作用的主导因子是温度和水分。 相似文献
993.
山洪灾害具有广泛性、突发性、破坏性等特征,开展山洪易发区的社区韧性评估,从而提高灾害应对能力是当前防灾减灾的前沿热点和难点。论文提出了一套多学科的综合方法:(1)利用中介效应明晰了山洪视角下社区韧性评价体系各指标间的定量化传递关系;(2)构建了基于决策实验室分析和解释结构模型的耦合数学模型,确定社区韧性影响因素的多级递阶解释结构模型,分析社区韧性的差异化影响因素;(3)采用信息扩散方法,定量分析山洪灾害社区韧性的变化趋势并排序。以粤北山洪易发区为例,从城镇、村落、城乡结合部3种类型社区进行灾害韧性分析。结果表明:山洪视角下的社区韧性指标体系是一个多维度多层次的复杂网络系统,包括环境、社会、心理、制度和信息沟通5个方面;不同类型社区灾害韧性的直接影响因素呈差异化特征,而供排水设施建设和洪灾应急演练为社区韧性的根本影响因素,对增强山洪视角下社区韧性发挥本质性作用;由于调研村落多位于山洪频发区,居民防范灾害、减轻灾害影响的意识较强,村落较城镇和城乡结合社区呈现出更高的韧性。研究可为提升粤北山洪易发区社区韧性及社区防灾减灾能力提供科学参考,该综合分析方法亦可为其他类型灾害的精细化防灾减灾提供支... 相似文献
994.
G.D. Ardizzone A. Belluscio M.F. Gravina A. Somaschini 《Estuarine, Coastal and Shelf Science》1996,43(6):665-676
AMytilus galloprovincialispopulation, settled on a new artificial habitat at 12 m depth in the Central Tyrrhenian Sea, was investigated for 10 years. The new substratum, located at a depth lower than the preferential range of the species, was colonized temporarily by mussels which reached very high densities and dominated the benthic community from their colonization until the third year. The length-frequency distribution analysis showed a progressively complex population structure with up to three cohorts. The yearly recruitments were observed once a year in spring. The growth curve provided a maximum length higher than that reported for shallow waters. Nevertheless, the gregarious habits of mussels and the reduced water movement caused edaphic modifications of the substratum, which was covered progressively by sediments and biodeposits (pseudofaeces). Consequently, the population structure was affected by a reduction of the newly recruited cohorts, and mussels disappeared after 5 years of colonization. This may be explained by the reduction in the substratum available for the first settlement (hydroid covering), as well as by the modification of the surface required for final settlement. 相似文献
995.
The invertebrate benthic community of two Aveiro salt pond systems was studied in order to evaluate its diversity, density and the influence of organic matter and salt production. Samples were collected monthly at Esmolas and Tanoeiras. Five groups of benthic organisms were found: Nemathelminthes, Annelida (Nereis diversicolor), Crustacea (Sphaeroma serratum andTanais cavolini), Insecta (Chironomidae), Bivalvia Mollusca (Cerastoderma edule, Spisula solida andMya arenaria) and Gasteropoda Mollusca (Hydrobia ulvae, Cingulla cingullus, Cingulla semistriata, Odostomia rissoides, Odostomia unidentata, Scrobicularia alba, Valvata cristata andPaludestrina acuta). The highest density of the benthic community was observed during the non-productive season in all but the crystallizing pond systems. In both salt ponds, salinity acted as limiting factor. The dominant group was Gasteropoda, although high densities of Bivalvia were recorded in some ponds. In the feeder pond and the channels, species diversity was highest in the Tanoeiras salt pond, probably because its physical and chemical characteristics allowed the development of stable communities. 相似文献
996.
997.
The Manzala Lagoon in Egypt's Nile Delta has become a sediment sink of reduced area and depth, with increased contaminant
levels. Loss of much-needed fresh to brackish water reserves and decreased fish catches have serious ramifications. Herein,
maps of temporal and regional sediment distributions in Manzala incorporate petrological and statistical analyses of 200 surficial
and short core samples. These provide baseline information needed to help implement protection measures for this vital wetland.
Four periods are considered: 1920s, 1940s, ∼1965, and 1990. Important depositional changes between 1940s and ∼1965 resulted
from anthropogenic effects on this quasi-closed lagoon system, including industrial buildup, wetland conversion to agricultural
land, and irrigation waterway development. Further modification from ∼1965 to 1990 is associated with closure of the Aswan
High Dam, continued construction of waterways that discharge waste water into lagoon margins, and marine incursion into the
northern lagoon. If current practices continue, the lagoon could be reduced to about one-third of its present area by 2050
AD.
Received: 2 October 1997 · Accepted: 13 January 1998 相似文献
998.
Hispanic Community Types and Assimilation in Mex-America 总被引:1,自引:0,他引:1
Terrence W. Haverluk 《The Professional geographer》1998,50(4):465-480
I argue that discrepancies among Hispanic assimilation models can be interpreted through three distinct types of Hispanic communities—continuous, discontinuous, and new. Continuous communities were founded by Hispanics and Hispanics have always been the majority population. As a result, Hispanics have not assimilated as predicted by traditional models. Discontinuous communities were originally settled by Hispanics, but eventually were filled by a minority population. Since WWII, many of these communities have experienced a Hispanic demographic resurgence making assimilation more problematic. Hispanics in new communities are recent immigrants to Anglo dominant communities and are more apt to follow the traditional assimilation model. 相似文献
999.
旅游目的地的社区化及社区旅游研究* 总被引:96,自引:2,他引:94
文章探讨了旅游目的地建设的社区化及社区旅游的特点,并从旅游社区中旅游资源的形成机理角度,探讨了旅游社区的分类及进化机制. 相似文献
1000.
Manuel?R.?Palacios-FestEmail author Simone?R.?Alin Andrew?S.?Cohen Brandon?Tanner Heather?Heuser 《Journal of Paleolimnology》2005,34(1):51-71
Fossil invertebrates from cores collected in Lake Tanganyika provide a record of probable nearshore ecological response to recent watershed deforestation and sediment erosion in several East African watersheds. We compared paleoecological profiles (primarily from ostracodes) from watersheds spanning a range of sizes and present-day deforestation disturbance levels to understand the timing and magnitude of faunal changes, and their relationship in time to terrestrially-derived disturbance indicators. Profiles from the Lubulungu and Nyasanga/Kahama Rivers (Tanzania) provide a record of faunal variability in watersheds that are currently undisturbed with respect to deforestation. These records indicate continuous faunal turnover through time. However, this pattern of turnover is accompanied by relatively high levels of diversity throughout the record, with no wholesale extinction events. Ostracode taphonomic data and other fossil abundance data from the Lubulungu area provide strong evidence in support of at least two episodes of lower lake levels, associated with episodes of Late Holocene aridity. Records from deltas of disturbed watersheds at the Kabesi River (Tanzania) and those of Northern Burundi all show a combination of profound and abrupt faunal turnover, in some cases accompanied by local extinction and establishment of a few dominant taxa. At the Mwamgongo River delta, fed from a very small, disturbed watershed, species turnover was subtler. In disturbed watershed cores showing abrupt faunal changes the transitions mostly occurred in the late 19th to early 20th centuries, predating the major mid-20th century increase in sediment mass accumulation rates, with the latter only correlated with changing fossil abundance and flux. However, the earlier faunal community changes are contemporaneous with both palynological and geochemical changes in the core profiles indicative of changing land-use patterns. This suggests that lacustrine ecosystem response to deforestation was a two-stage process, with an earlier phase of response to changing quality of sediments or dissolved matter being discharged from the watershed, and a subsequent phase responding to increased quantity of sediment. 相似文献