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1.
M Fevrier 《Comparative immunology, microbiology and infectious diseases》1985,8(2):159-170
Antibody response to an antigen involves the co-operation between three types of cells: macrophages, T cells and B cells. The cognate interactions between these cells play a fundamental role in the expression of a specific antibody response, but the last is modulated by antigen-nonspecific soluble factors produced either by macrophages or by T cells. Macrophages elaborate a spectrum of molecules modulating the function of lymphoid cells; among them are IL1 and prostaglandins of the E series, which are respectively enhancer and inhibitor of the antibody response in vitro. These molecules alter T cell and B cell activities through different mechanisms involving activation or inhibition of IL2 production, or alteration of cells surface antigens. However, the cellular events following the fixation of soluble factor on its receptors are not known. 相似文献
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基于EXCITE TD软件对某型柴油机前端附件轮系进行建模仿真,得到了该机型在不同转速下的V带滑动率、V带振幅、张紧轮摆动角度等动力学数据,并通过评价指标对该V带轮系进行了性能评估。 相似文献
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含硫氨基酸与铜对肉鸡胫骨软骨发育不良的影响 总被引：1，自引：0，他引：1
研究日粮过量含硫氨基酸 （ 简称 Ｓ Ａ Ａ , 为推荐量的１５ 倍） 与高铜 （８８６６ ｍｇ／ｋｇ , 为推荐量的１０ 倍） 对肉鸡胫骨软骨发育不良 （ Ｔ Ｄ） 的影响。试验采用半纯合饲粮 （ 含 Ｃｕ ０６６ ｍｇ／ｋｇ） , 试验处理分为正常 Ｓ Ａ Ａ 与 Ｃｕ 组, 高 Ｓ Ａ Ａ 与正常 Ｃｕ 组, 正常 Ｓ Ａ Ａ 与高 Ｃｕ 组和高 Ｓ Ａ Ａ 与高 Ｃｕ 组,试验期２１ ｄ 。结果： 过量 Ｓ Ａ Ａ 降低肉鸡体重、饲料转化率、骨灰、肝 Ｃｕ 、胰 Ｃｕ （ Ｐ ＜ ００１ 或 Ｐ ＜ ００５） , 增加胫骨长度 （ Ｐ ＜ ００５） , 诱发 Ｔ Ｄ发病率升高 （ Ｐ ＜ ００１） , Ｔ Ｄ 指数显著上升 （ Ｐ ＜ ００５） 。高 Ｃｕ 日粮增加肝 Ｃｕ 、肾 Ｃｕ 沉积 （ Ｐ ＜ ００１ 或 Ｐ ＜ ００５） , 提高饲料转化率 （ Ｐ ＜００５） , 但不诱发肉鸡 Ｔ Ｄ 发病率增加。添加高 Ｃｕ 对过量 Ｓ Ａ Ａ 致肉鸡 Ｔ Ｄ 发病率上升无减缓作用, 适宜的 Ｓ Ａ Ａ 和 Ｃｕ 水平是促进肉鸡生长、降低肉鸡 Ｔ Ｄ 发病率的重要限制因素之一。 相似文献
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Rath NC Kannan L Pillai PB Huff WE Huff GR Horst RL Emmert JL 《Research in veterinary science》2007,83(2):244-250
Two trials were conducted to determine if thiram-induced tibial dyschondroplasia (TD) in chickens was linked to a vitamin D deficiency and calcium homeostasis dysregulation, and whether feeding vitamin D fortified diets may prevent it. Day-old chickens were given grower diets containing different vitamin D products throughout the experiment until necropsy on day 16. Half of the birds in each feed group received thiram at levels of 100 ppm (trial 1) or 50 ppm (trial 2) between days 7-9 to induce TD. The birds were weighed, bled, and euthanized to determine TD incidences and severity by examining the growth plates. Tibial bones were used to measure biomechanical strength and ash content. Blood concentrations of 25-hydroxyvitamin D, Ca, P, alkaline phosphatase, and creatine kinase were measured in serum that showed no differences between different groups. Thiram reduced body weight and induced TD regardless of any vitamin D treatment to the same extent as untreated birds. 相似文献
6.
Jenny Ruales Baboo M. Nair 《Plant foods for human nutrition (Dordrecht, Netherlands)》1992,42(1):1-11
The nutritional quality of protein in quinoa seeds has been determined by amino acid assay and by animal feeding experiments. The amino acid composition of the protein in raw quinoa and washed quinoa show similar pattern. The first limiting amino acids were the aromatic amino acids thyrosine + phenylalanine giving a chemical score of 86 for protein in raw quinoa and 85 for protein in washed quinoa. Threonine was the next limiting amino acid followed by lysine. The amount of lysine and sulfur amino acids (methionine + cystine) was relatively high. In general, the content of essential amino acids in quinoa is higher than in common cereals. The animal experiments showed NPU values of 75.7, BV of 82.6 and TD value of 91.7 for the protein in raw quinoa. Results of the in-vitro enzymatic methods showed that the digestibility of the protein in quinoa is comparable to that of other high quality food proteins. The corresponding experiments carried out with samples of guinoa seeds, which have been processed to remove the saponins, showed that, the saponins do not exert any negative effect on the nutritive quality of the protein. 相似文献
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BACKGROUND: Current quantitative methods for airborne dichlorodiphenyltrichloroethane (DDT) require collection and extraction times of ≥ 12 h. The aim of this study was to develop a method for quantifying airborne DDT with a short (<4 h) collection and analysis time. RESULTS: Precision [relative standard deviation (RSD)] for each calibration point (0.8–9.0), linearity (R2 = 0.99) and apparent recovery (R′ = 96.5%) were determined from thermal desorption (TD) gas chromatography–mass spectrometry (GC-MS) analyses of Tenax-TA-packed sampling tubes spiked with 1–250 ng of DDT. Recovery of 13C-labeled 4,4′-DDT from tubes spiked before and after air sampling was 97.3 and 90.3% respectively. DDT was detected and quantified in 1–3 L samples of air collected during 10–180 min sampling events. A significant difference was observed in DDT air concentration between 28 and 33 °C during microchamber studies. CONCLUSIONS: The results demonstrate that the TD GC-MS method developed in this study is precise, reproducible and linear over the span of 1–250 ng of DDT spiked onto TD tubes. By avoiding dilution of the sample, the method described allows the measurement of DDT vapor concentrations during short sampling periods (10–180 min) relevant to mosquito behavior studies. Published 2012 by John Wiley & Sons, Ltd. 相似文献
8.
饮水高氯诱发肉鸡胫骨软骨发育不良的试验研究 总被引：6，自引：2，他引：4
２４０羽健康ＡＡ肉鸡随机均分为对照组，试验１组，试验２组。从８日龄志分别饮用含Ｃｌ０．０％、０．０９％、０．１８％的饮水以观察肉鸡胫骨软骨发育情况，同时对其进行了Ｘ射线、骨密度、血清学和形态学的研究。结果表明：（１）饮水高氯可增加胫骨软骨发育不良的发病率。（２）３周后病鸡胫骨近端的Ｘ射线可透区与软骨增生区的形态一致，其承重侧的骨皮质增厚。（３）试验组鸡的胫骨骨密度较对照组稍高，但差异不显著。骨密度 相似文献
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双季水稻叶片温度变化规律及其与产量关系的研究 总被引：5，自引：2，他引：3
为了研究水稻叶片温度与产量关系,以双季早晚稻12个品种为材料,2008-2009年应用红外测温仪记录叶片温度,并分析大气温度、气叶温差与产量的关系。结果表明,水稻叶片温度的日变化呈单峰曲线,变化幅度小于气温;在不同生育阶段品种间气叶温差存在明显差异。各生育时期14:00点的气叶温差与产量呈正相关关系,抽穗期的相关程度最高;抽穗期和抽穗后的剑叶日平均温度与产量呈负相关,剑叶的日平均气叶温差与产量呈正相关;超级稻的气叶温差高于非超级稻。 相似文献
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采用降落PCR方法扩增目的基因,设计两次正交试验对PCR反应体系中的各组分浓度进行筛选,同时对退火时间、延伸时间及循环次数进行摸索。结果表明,适合北方黑钙土土壤细菌16S rDNA扩增体系为:在25μl体系中,10×buffer2.5μl,DNA模板20ng,Mg2+2.5mmolL-1,dNTPs0.25mmolL-1,引物0.3μmolL-1,TaqDNA聚合酶1.5U。降落PCR扩增程序为:95℃,5min;95℃,45s;65~56℃,60s;72℃,90s;每两个循环降低1℃。95℃,45s;5.5℃,60s;72℃,90s;10个循环。最后72℃,10min。 相似文献