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91.
Living in poverty is associated with high levels of protracted stress associated with health problems. Economic and food insecurity are particularly poignant aspects of poverty and condition the work of securing basic daily needs of families. Recent studies suggest that levels of stress increase as family food needs rise. This paper presents new findings which clarify the relationship of food provisioning to stress levels, by examining actual food provisioning strategies and food insecurity among the Northern Cheyenne Indians of southeastern Montana. Results clearly show that stress varies by types of food acquisition strategies. Contrary to our expectations, more complex strategies, including relatively unpredictable and cumbersome food provisioning activities, are not linked to higher stress levels in our analysis. Controlling for food security levels, households using a combination of local programs and informal subsistence sources are the least stressed, despite the demands of managing a large number of food sources. Households primarily using Food Stamps are the most likely to experience high levels of stress. Interviews with Food Stamp recipients show that potential sources of stress include inadequate allocations of Food Stamps, difficulty achieving and maintaining eligibility, challenges to complying with paperwork and appointment requirements, as well as personal obstacles and community barriers to making food stamps last. Analyses indicate that contradictions between local cultural norms for food provisioning and the realities of food insecurity in this context promote strategies emphasizing greater independence from federal food programs.  相似文献   
92.
To select a reliable and sensitive method for discriminating strains of Porphyra haitanensis, the nucleotide sequence of the internal transcribed spacer 1 to internal transcribed spacer 2 regions (ITS-5.8S) of nuclear ribosomal DNA and the intergenic spacer region of RUBISCO were compared in five wild and five cultivated Porphyra haitanensis strains. Based on molecular analyses, sequences of ITS-5.8S (about 1,210 bp) could be divided into three regions: ITS1, 5.8S, and ITS2. The ITS1 and ITS2 sequences of each strain differed, even between individuals collected from the same site. In contrast, 5.8S rDNA and RUBISCO spacer sequences were identical among the ten P. haitanensis strains, although differences were found among different Porphyra species. Phylogenetic analysis also supported these conclusions. These sequence features of highly conserved regions and diversified regions that occurred repeatedly in ITS-5.8S could be useful in discriminating germplasm of P. haitanensis strains or Porphyra species. In contrast, the RUBISCO spacer is only suitable for identifying Porphyra species. New coupled primers were designed to amplify only the 5.8S rDNA and ITS2 region of Porphyra. The sequences of these amplified fragments can be readily used to identify germplasm or to perform phylogenetic analysis of Porphyra spp.  相似文献   
93.
A study was conducted to investigate the effects of skid trail slope and traffic levels on soil disturbances at two soil depths (0–10 and 10–20 cm). The treatments were set at four traffic levels (2, 7, 12 and 20), two slope classes (<20% and >20%) and two soil depths (0–10 and 10–20 cm). Results show that skidder traffic, longitudinal slope and soil depth have significant effect on soil bulk density in skid trail. Comparison of average soil bulk density in different traffic levels shows that there are significant differences in average bulk density between different traffic levels and control (p<0.05). The average bulk densities in different slopes and soil depths are significantly increased with increase in traffic levels, maximized at 12 passes (p<0.05), but there are no significant differences between 12 and 20 passes. The interaction effects between traffic and soil depth are significant (F 0.05,3=0.109, p<0.001). For all traffic treatments, there are significant differences in soil moisture content between the two slope classes and the two depths (p<0.001). However, the interaction effects between traffic levels and slope classes are not significant (p >0.05), although skidder traffic and slope affected soil moisture content.  相似文献   
94.
Since 1900, soil organic matter (SOM) in farmlands worldwide has declined drastically as a result of carbon turnover and cropping systems. Over the past 17 years, research trials were established to evaluate the efficacy of different commercial humates products on potato production. Data from humic acid (HA) trials showed that different cropping systems responded differently to different products in relation to yield and quality. Important qualifying factors included: source; concentration; processing; chelating or complexing capacity of the humic acid products; functional groups (Carboxyl; Phenol; Hydroxyl; Ketone; Ester; Ether; Amine), rotation and soil quality factors; consistency of the product in enhancing yield and quality of potato crops; mineralization effect; and influence on fertilizer use efficiency. Properties of humic substances, major constituents of soil organic matter, include chelation, mineralization, buffer effect, clay mineral-organic interaction, and cation exchange. Humates increase phosphorus availability by complexing ions into stable compounds, allowing the phosphorus ion to remain exchangeable for plants’ uptake. Collectively, the consistent use of good quality products in our replicated research plots in different years resulted in a yield increase from 11.4% to the maximum of 22.3%. Over the past decade, there has been a major increase in the quality of research and development of organic and humic acid products by some well-established manufacturers. Our experimentations with these commercial products showed an increase in the yield and quality of crops.  相似文献   
95.
The hollowness of crosslinked hollow phenolic fibers was regulated successfully from 9 % to 80 % by adjusting the curing temperature of the partially crosslinked fibers. The partially crosslinked fibers was studied in detail by mass gained, tensile strength, solvent dissolution, SEM, IR, and TG analysis, and the prepared hollow phenolic fibers with different degrees of hollowness were characterized with SEM, tensile strength, TG-DSC and TG-MS. The results show that the factor determining the hollowness is the crosslinked extent of the partially crosslinked fibers and the hollow fibers with different degrees of hollowness have similar crosslinkage, mechanical properties and thermal stability.  相似文献   
96.
Two experiments were undertaken to select the efficient method applied for goat estrous synchronization. In experiment 1, a total of 120 does (Capra hircus) were divided into five groups with a randomized block design, and the does of treatment 1 were synchronized by intravaginal sponges impregnated with 30 mg Levonorgestrel inserted for 10 days. Does of treatments 2, 3, and 4 were treated with further injection of 25 IU follicle-stimulating hormone (FSH), 0.05 mg prostaglandin F2 alpha (PGF), and 25 IU FSH + 0.05 mg PGF at sponge withdrawal, respectively. The does in the control group (n = 40) without estrous synchronization treatment and natural estrous does were observed. In experiment 2, a total of 140 does in five goat farms in breeding and non-breeding seasons were treated with the selective efficient procedure. The results presented that all the employed treatments were capable of inducing and synchronizing estrous goats. According to estrous response and economy, the use of intravaginal sponges impregnated with 30 mg Levonorgestrel and 0.05 mg PGF (treatment 3) is the first choice for estrous synchronization, and 95.0% of synchronized does demonstrated estrus, which was significantly higher than that of treatment 1 (P < 0.05) and control group (P < 0.01). The percentages of ovulating of treatments 3 and 4 were the same (95.0%), which were significantly higher than that of treatment 1 (P < 0.01). The ovulation rates among different groups were not significant (P > 0.05). When the selective procedure was applied to five goat farms, 85.7% (120/140) of does demonstrated estrus, and the kidding percentage, litter size, and prolificacy rate were 53.6%, 0.95, and 177%, respectively.  相似文献   
97.
The comparative effects of iron-supplemented levels on growth, tissue distribution, haematology and immunology of gilthead sea bream, Sparus aurata (2 g) were investigated, using four organic (50, 100, 200, 300 mg ORG/kg diet) and one inorganic iron source (200 INOR mg/kg diet). Fish were treated for 12 weeks with the experimental diets and maintained at a water temperature of 19–22°C. Growth (final weight and specific growth rate), tissue distribution (spleen, liver and muscle), haematological parameters (red blood cells, haematocrit, haemoglobin and mean corpuscular haemoglobin concentration) and non-specific immune indexes (respiratory burst activity and antibacterial activity of serum) were analysed. No significant differences were found in growth and iron tissue distribution among the tested groups. Red blood cell counting was statistically higher in fish given 50 ORG, 100 ORG, 200 ORG and 200 INOR feeds. However, haematocrit, haemoglobin and mean corpuscular haemoglobin concentration were not significantly affected by increasing dietary iron. Fish receiving the 100 ORG diet had the best performance with respect to the respiratory burst activity and significantly higher values for antibacterial activity of serum were obtained in fish fed with the 300 ORG diet. The present findings provided no clear evidence of the optimum iron concentration. However, there was adequate indication that iron supplementation enhanced the performance of gilthead sea bream, mainly from a haematological and immunological point of view.  相似文献   
98.
99.
水稻广亲和温敏不育系株1 S的选育及应用   总被引:48,自引:16,他引:32  
株1S是用遗传 远的不同生态类型材料杂交充 灿型广亲和温敏不育系。育性转换临界温度23℃左右,在湖南稳定不育期90d以上,开花习性好,异交结实率40%以上。海南冬敏少本地低温水深灌繁殖自交结实率在30%以上,具有广亲和性,一般配合力和特殊配合力均较强,用其选配的早晚稻组合已有4个参加省区试。具有广阔的应用前景。  相似文献   
100.
牛羊4种寄生虫病联合诊断技术的研究与应用   总被引:1,自引:1,他引:0  
疫区牛羊同时寄生有捻转血矛线虫、日本血吸虫、伊氏锥虫和肝片吸虫等多种寄生虫。目前血清学诊断方法对这 4种寄生虫病的检测需 2~ 4次操作。将捻转血矛线虫、日本血吸虫、伊氏锥虫和肝片吸虫抗原分别以 0 1 5 ,0 0 4 ,0 0 6和 0 1 3μg/ μL的最佳浓度依次定点在同一硝酸纤维素膜条上 ,制成 4种寄生虫病联合诊断膜。用黄牛IgG ,水牛IgG和山羊IgG联合免疫兔 ,获得了高效价兔抗黄牛、水牛和山羊 (简称兔抗牛羊 )IgG抗血清。应用兔抗牛羊IgG抗血清连接酶标SPA ,建立了 1份血纸能同时用于检测牛、羊捻转血矛线虫、日本血吸虫、伊氏锥虫和肝片吸虫病抗体技术。经浙江、湖北、四川、安徽等省应用 ,该项技术具有省工、省时、经济、实用等优点。适宜于牛、羊捻转血矛线虫、日本血吸虫、伊氏锥虫和肝片吸虫病流行区的普查或监测  相似文献   
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