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31.
试验采用含钙0.88%和1.78%的玉米—豆饼型基础饲粮(含锌29ppm,添加0.10和40ppm锌(ZnSO_4·7H_2O)。结果表明,随着饲粮锌水平的提高,雏鸡增重显著提高(P<0.01),这种效应随着雏鸡周龄的增长愈趋明显。饲粮高钙使雏鸡前期增重显著降低(P<0.01),后期效应愈趋缓解。血清碱性磷酸酶的活性随着饲粮锌水平的提高而显著提高(P<0.01),饲粮高钙使之显著降低(P<0.01)。饲粮加锌使血清白蛋白含量显著高于未加锌组(P<0.05),饲粮高钙使血清白蛋白含量显著降低(P<0.01),使血清球蛋白含量显著提高(P<0.01),而血清总蛋白含量不受饲粮钙水平显著影响(P>0.05)。肝脏(P<0.05)、肾脏(P<0.01)、胰脏(P<0.01)、胫骨(P<0.01)以及粪便排泄物(P<0.01)中锌含量随饲粮锌水平的提高而显著提高,肺脏锌含量没有明显变化(P>0.05)。饲粮高钙使肾脏(P<0.05)、肺脏(P<0.01)、胫骨(P<0.05)锌含量显著降低,使粪便排泄物中锌含量显著提高(P<0.05)。饲粮中含锌29ppm,不能满足雏鸡维持正常代谢和生长发育的营养需要,饲粮高钙时,饲粮总锌69ppm为宜。  相似文献   
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The formation of high-quality thin films of polytetrafluoroethylene (PTFE) is important in many applications ranging from material reinforcement to molecular electronics. Laser ablation, a technique widely used to deposit a variety of inorganic materials, can also be used as a simple and highly versatile method for forming thin polymer films. The data presented show that PTFE films can be produced on various supports by the evaporation of a solid PTFE target with a pulsed ultraviolet laser. The composition of the ablation plume suggests that PTFE ablation and subsequent film formation occur by way of a laser-induced pyrolitic decomposition with subsequent repolymerization. The polymer films produced by this method are composed of amorphous and highly crystalline regions, the latter being predominantly in a chain-folded configuration with the molecular axis aligned parallel to the substrate surface.  相似文献   
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Using genomic and mass spectrometry-based proteomic methods, we evaluated gene expression, identified key activities, and examined partitioning of metabolic functions in a natural acid mine drainage (AMD) microbial biofilm community. We detected 2033 proteins from the five most abundant species in the biofilm, including 48% of the predicted proteins from the dominant biofilm organism, Leptospirillum group II. Proteins involved in protein refolding and response to oxidative stress appeared to be highly expressed, which suggests that damage to biomolecules is a key challenge for survival. We validated and estimated the relative abundance and cellular localization of 357 unique and 215 conserved novel proteins and determined that one abundant novel protein is a cytochrome central to iron oxidation and AMD formation.  相似文献   
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Fifty wheat varieties along with Jupateco-73 and Morocco were studied for the expression of leaf tip necrosis (LTN), a trait linked with the durable rust resistance gene pair Lr34/Yr18. LTN was frequent (i.e., ≥6) in nine replications of a field experiment over 3 years in 17 genotypes, and the varieties were considered positive for LTN. In molecular analyses of these varieties, having relative severity values up to 78 for yellow rust and 45 for leaf rust, the 150-bp Lr34/Yr18-linked allele was consistently amplified. Expression of LTN in six of nine replications is an appropriate threshold for predicting the presence of Lr34/Yr18 gene pair, and genotypes can be selected using this trait.  相似文献   
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This paper presents the results of irrigated rotation experiment, conducted in the North West Frontier Province (NWFP), Pakistan, during 1999–2002 to evaluate effects of residues retention, fertilizer N and legumes in crop rotation on yield of maize (Zea mays L.) and soil organic fertility. Chickpea (Cicer arietinum L) and wheat (Triticum aestivum L) were grown in the winters and mungbean (Vigna radiata) and maize in the summers. Immediately after grain harvest, above-ground residues of all crops were either completely removed (−residue), or spread across the plots and incorporated by chisel plough by disc harrow and rotavator (+residue). Fertlizer N rates were nil or 120 kg ha−1 for wheat and nil or 160 kg ha−1 for maize. Our results indicated that post-harvest incorporation of crop residues significantly (p < 0.05) increased the grain and stover yields of maize during both 2000 and 2001. On average, grain yield was increased by 23.7% and stover yield by 26.7% due to residue incorporation. Residue retention also enhanced N uptake by 28.3% in grain and 45.1% in stover of maize. The soil N fertility was improved by 29.2% due to residue retention. The maize grain and stover yields also responded significantly to the previous legume (chickpea) compared with the previous cereal (wheat) treatment. The legume treatment boosted grain yield of maize by 112% and stover yield by 133% with 64.4% increase in soil N fertility. Similarly, fertilizer N applied to previous wheat showed considerable carry over effect on grain (8.9%) and stover (40.7%) yields of the following maize. Application of fertilizer N to current maize substantially increased grain yield of maize by 110%, stover yield by 167% and soil N fertility by 9.8% over the nil N fertilizer treatment. We concluded from these experiments that returning of crop residues, application of fertilizer N and involvement of legumes in crop rotation greatly improves the N economy of the cropping systems and enhances crop productivity through additional N and other benefits in low N soils. The farmers who traditionally remove residues for fodder and fuel will require demonstration of the relative benefits of residues return to soil for sustainable crop productivity.  相似文献   
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Irrigation of arable land with contaminated sewage waters leads to the accumulation of trace metals in soils with subsequent phyto‐/zootoxic consequences. In this study, biochar derived from cotton sticks was used to amend an agricultural silt‐loam soil that had been previously irrigated with trace metal contaminated sewage waters. Metal accumulation and toxicity to spinach (Spinacia oleracea) and fenugreek (Trigonella corniculata) was investigated by measuring concentrations of Cd and Ni in plant tissues and various photosynthetic and biochemical activities of plants. Positive impacts of biochar on both spinach and fenugreek were observed in terms of biomass production that increased from 29% to 36% in case of spinach, while for fenugreek this increase was 32% to 36%. In the control treatment there was an increase in malondialdihyde, soluble sugar, and ascorbic acid contents, indicating heavy metal stress. Biochar applications increased soluble proteins and amino acids in plants and reduced the uptake of Cd from 5.42 mg kg?1 at control to 3.45 mg kg?1 at 5% biochar amended soil and Ni (13.8 mg kg?1 to 7.3 mg kg?1 at 5% biochar) by the spinach plants. In fenugreek, the Cd was reduced from 7.72 mg kg?1 to 3.88 mg kg?1 and reduction in Ni was from 15.45 mg kg?1 to 9.46 mg kg?1 at 5% biochar treated soil, reducing the possibility of transfer up the food chain. This study demonstrates that the use of biochar made from cotton‐sticks, as an amendment to arable soils that have received contaminated irrigation water, could improve plant growth and decrease Cd and Ni uptake to crops, alleviating some of the negative impacts of using sewage waters on arable land.  相似文献   
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Foreign bodies in the soft tissues are frequent problems in both veterinary and human medical practice. Radiography has been the principle tool for diagnosis, but is unable to define many foreign bodies. This study was undertaken to compare the sonographic and radiographic visualization for a variety of foreign bodies. Fresh turkey muscle (pectoral and thigh) with skin was used as the soft tissue model. Assorted foreign bodies were introduced 1 cm into the muscle. Materials examined were small wood fragments, steel wire, glass, nails, graphite, rock, BB pellets, and polystyrene plastic. Following introduction of the foreign bodies radiographs were obtained and the specimens were studied sonographically at 5.0 mHz and 7.5 mHz. All foreign bodies were visible with sonography. A bright echo with either acoustic shadowing or reverberations was present for all specimens. Radiographically metallic foreign bodies were visible but wood, some graphite, and plastic were not seen. We conclude that radiography should remain the primary imaging modality for foreign body detection because of its general availability and low cost. If radiography is negative ultrasound can detect and guide the removal of radiolucent foreign bodies.  相似文献   
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