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141.
A collecting expedition has been carried out in the inland areas of the Basilicata Region, South Italy. Each of the 14 selected municipalities was subdivided in three strata based on the geographical distribution of population and orography: 1. city boundaries, 2. group of country houses, 3. isolated farm houses. Five sites were selected within each stratum/town for a total of 185 sites. In 101 sites crop species germplasm was collected and the farmer-maintainers were interviewed. Altogether 350 accessions were collected, the most common species were Capsicum annuum, Lycopersicon esculentum and Phaseolus vulgaris. A significant number of landraces are still preserved on farm, mostly in isolated farm houses (average age of farmers: 60?years) adopting traditional farming systems but a number of young farmers were also present. Perspectives for on farm conservation and management are discussed and public economic support for “farmer-maintainers” proposed.  相似文献   
142.
The presence of illicit drugs and their metabolites in surface waters has to be considered a new type of hazard, still unknown, for the aquatic ecosystem, due to the potent pharmacological activities of all the illicit drugs. Our research was therefore aimed at evaluating the impact of illicit drugs on the aquatic fauna, till now still undervalued. To this aim, we verified the ability of the European eel (Anguilla anguilla), a well-known biomonitor of environmental contamination, to bioaccumulate cocaine, one of the most abundant illicit drugs found in surface waters. Silver eels were exposed to a nominal cocaine concentration of 20?ng/l for 1?month; at the same time, control, carrier, and post-exposure recovery groups were made. Brains, gills, liver, kidney, muscle, gonads, spleen, digestive tract, and sections of dorsal skin were assayed by high-pressure liquid chromatography. Cocaine was found in the tissues of the treated eels and, at low concentrations, in almost all tissues of post-exposure recovery eels. These results indicate that cocaine is able to accumulate into the eel tissues; its presence suggests potential risks for eels since cocaine could affect their physiology and contribute to their decline, and for humans consuming contaminated fish.  相似文献   
143.
采用15N-甘氨酸单剂量终产物法研究了妊娠和非妊娠母猪在不同阶段整体蛋白质代谢的周转速率以及氨基酸利用效率的差异。结果表明:刚配种时,妊娠母猪与非妊娠母猪蛋白质代谢参数差异不显著(P>0.05);妊娠30d时,妊娠母猪蛋白质合成速率,降解速率、周转速率显著低于非妊娠母猪(P<0.05),但沉积速率提高了25%(P<0.05);妊娠后期,妊娠母猪氨基酸代谢库氮流量、周转速率以及蛋白质合成速率和降解速率显著(P<0.01)提高,蛋白质的沉积速率增加了71.1%(P<0.01)。  相似文献   
144.
The importance of plant volatiles in mediating interactions between plant species is much debated. Here, we demonstrate that the parasitic plant Cuscuta pentagona (dodder) uses volatile cues for host location. Cuscuta pentagona seedlings exhibit directed growth toward nearby tomato plants (Lycopersicon esculentum) and toward extracted tomato-plant volatiles presented in the absence of other cues. Impatiens (Impatiens wallerana) and wheat plants (Triticum aestivum) also elicit directed growth. Moreover, seedlings can distinguish tomato and wheat volatiles and preferentially grow toward the former. Several individual compounds from tomato and wheat elicit directed growth by C. pentagona, whereas one compound from wheat is repellent. These findings provide compelling evidence that volatiles mediate important ecological interactions among plant species.  相似文献   
145.
本文以湿增压动力装置实验台为物理模型,为进行相关实验完成了速度、流量、扭矩等重要参数的测量,并以N16221硬件为基础,基于虚拟仪器平台LabVIEW研制了实验台的测试软件。新设计的测试系统是基于虚拟仪器平台的模块化系统,使得研究人员的大部分精力集中于所要实现的功能上,而不是以往繁琐的算法和重复的编程上,参数易于修改,缩短了系统开发的周期,能满足实验需求。  相似文献   
146.
The objectives of this study were: (1) to predict the rumen fermentation pattern from milk fatty acids using a machine learning technique, i.e. artificial neural networks (ANN) combined with feature selection and (2) to compare the prediction accuracy of the resulting model to that of a statistical multi-linear regression model, based on odd and branched chain milk fatty acids. Data were collected from 10 experiments with rumen fistulated dairy cows, resulting in a dataset of 138 observations. Feature selection was based on correlation and principal component analysis, and background physiological knowledge. Different ANN architectures and training algorithms were assessed. The evaluation of the model performance, based on the test dataset, showed a root mean square prediction error, expressed relative to the observed mean, of 2.65%, 7.67% and 7.61% of the observed mean for acetate, propionate and butyrate, respectively. Compared to a multi-linear regression model, the ANN revealed not to perform significantly better. However, the results confirm that milk fatty acids have great potential to predict molar proportions of individual volatile fatty acids in the rumen.  相似文献   
147.
为提高虾青素的稳定性,采用超声的方法将卵磷脂和壳聚糖在水相溶液中自聚集形成散性的纳米粒。对影响纳米粒的制备与性质的因素进行分析,发现在卵磷脂/壳聚糖比例为5∶1到20∶1(w/w)条件下,超声15 min可形成稳定的纳米包载体系。粒径范围在137.51~139.46 nm之间且带有正电荷,粒径分布均匀。在电镜下观察为不规则的球状。制备得到虾青素纳米粒的包封率和包载量为51.02%和10.34%。虾青素纳米载体在pH 1.2、pH 6.8和pH 7.4的条件下,72h内释放约66.97%、30.34%和28.19%,具有较好的控制缓慢释放的作用。可见,壳聚糖/卵磷脂纳米载体是理想的虾青素功能食品载体。  相似文献   
148.
试验结果表明:空间诱变甜椒的3个营养品质性状(果实维生素C含量、可溶性固形物含量和糖酸比)在M3代的变异趋于稳定,株系内的株间变异均小于株系间变异,果实维生素C含量和糖酸比在群间的差异不显著,可溶性固形物含量在群间的差异显著;维生素C含量与可溶性固形物含量呈极显著正相关,与糖酸比呈极显著负相关,可溶性固形物含量与糖酸比呈显著正相关。宜筛选单株果实维生素C含量高、可溶性固形物含量和糖酸比适中的株系。优选的株系为A6、A7、C7、B2、B6、B1、A5、C5、B7、C4、A3、B5、A4和C6。  相似文献   
149.
AHP法在番茄果实商品性状评价上的应用分析   总被引:6,自引:0,他引:6  
陈贤  池涛  杨德 《西南农业学报》2008,21(2):432-435
本试验以AHP法对7个番茄品系的果实商品性状进行了综合评价与分析,构建了涵盖3个层次(目标层、标准层和指标层),6个指标(外观品质的单果重、果色和营养品质的维生素C、可溶性固形物和水分含量以及糖酸比)的番茄果实商品性状的综合评价指标体系。结果表明:品系YH02—6果实的综合商品性状较优,其果实的营养品质的分值在综合得分中所占的比重大;品系YH02-9、YH02—1和YH02-7果实的综合商品性状较好,其中品系YH02—1、YH02-7的得分点主要是外观品质,而品系YH02-9的主要得分点是营养品质;品系YH02-8、YH02-5和YH02—11果实的综合商品性状一般。验证了AHP法对于番茄果实商品性状进行综合评价与分析是一种实用、快捷、有效的多层次的综合评价与分析方法。  相似文献   
150.
印楝素与三种杀虫剂对小菜蛾的联合毒力作用   总被引:2,自引:0,他引:2  
采用浸叶浸虫法,测定了印楝素与三种杀虫剂对小菜蛾的室内联合毒力作用,并筛选出了药剂的最佳复配比例。结果表明,印楝素:阿维菌素为2.3:1,共毒系数(CTC)为141.14,增效作用最为显著;印楝素:Bt为1:1,共毒系数为136.74;而印楝素与高效氯氰菊酯混配对小菜蛾表现为相加作用。  相似文献   
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