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91.
1990—1992年三年试验结果表明,尽管只施氮磷肥可获得高产,但在施氮磷肥的基础上按比例配施钾肥,可进一步提高向日葵的产量.钾肥的最佳经济施肥量为150公斤K2O/公顷,N、P2O6、K2O最适比例为2∶1∶2. 相似文献
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首先论述了问卷调查方法产生的历史必然性 ,进而分析了问卷调查表的设计与具体操作中的不完善之处 ,并提出了具体的改进措施。 相似文献
95.
测定了番茄条斑分离物(TMV-L1)、番茄花叶分离物(TMV-L2)、小青菜花叶分离物(TMV-B1)、大白菜灰心病分离物(TMV-B2)、地黄病毒病分离物(TMV-R)和烟草花叶分离物(TMV-N)在22科82种植物上的反应。六个分离物在心叶烟、曼陀萝等7种植物的接种叶上出现局部枯斑、在番茄,龙葵等9种植物上出现系统花叶,在White Barley烟,青箱等10种植物上反应的症状不同,在测试的十字花科植物、菊科等22种植物上六个分离物的侵染力不一致,部分分离物能够侵染,部分分离物不能侵染。对百合科、大麻科等11个科中的测试植物都没有侵染力。六分分离物中只有TMV-B1和TMV-B2寄主范围基本一致,仅症状轻重不同。 相似文献
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ZHANG Hang LI Xinpu WU Xiaohu DING Xuezhi YAN Zuoting WANG Shengyi LI Hongsheng 《畜牧兽医学报》1956,51(11):2903-2910
The objective of the present study was to investigate the biofilm formation, antimicrobial resistance, virulence genes, and agr genotypes of Staphylococcus aureus (S. aureus) isolated from bovine mastitis cases, and to analyze the correlations between agr genotypes and virulence genes. Biofilm formation, antimicrobial resistance, and virulence genes for 336 strains of S. aureus were detected by microtiter plate method, disk diffusion method, and PCR respectively, and the agr typing of tested strains was determined by multiplex PCR. The results showed that all 336 strains of S. aureus from bovine mastitis were biofilm producers, among which 52.1% and 47.9% of isolates tested were moderate (++) and strong (+++) biofilm producers, respectively. Antimicrobial susceptibility testing demonstrated that S. aureus strains were highly resistant to penicillin, with a resistance rate of 91.7%, followed by erythromycin (89.6%), kanamycin (72.9%), clindamycin (66.7%) and gentamicin (60.4%). However, all isolates were sensitive to nitrofurantoin and linezolid. PCR results showed that the prevalence of fnbA gene was the highest (99.7%), followed by icaD (98.2%), icaA (89.6%), clfA (86.0%), cna (56.0%), and bap (14.6%) genes. Moreover, the sea, seb, sec and tst genes were found in 26.5%, 8.3%, 6.8% and 8.3% of the isolates, respectively. The agr typing results showed that S. aureus strains belonging to agr Ⅰ was predominant in our study, accounting for 77.1% of the isolates, and the frequencies of agr Ⅱ, agr Ⅲ and agr Ⅳ genotypes were 14.0%, 4.8% and 2.1%, respectively. Statistical analysis indicated that the strains of S. aureus belonging to agr Ⅰ genotype have the potential to carry more virulence genes, while no toxin genes could be found in any of the strains belonging to agr Ⅳ. The results revealed high antimicrobial resistance to common antimicrobial agents in S. aureus isolated from bovine mastitis milk samples. Moreover, agr Ⅰ was the predominant genotype with diverse toxin genes in S. aureus from bovine mastitis, and the potential hazard should be of concern. 相似文献
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在标准实验室环境里,对渔用自增强聚乙烯(self-reinforced polyethylene,简称SRPE)单丝的结晶形态、拉伸力学性能进行了分析。结果表明:渔用SRPE单丝结晶度、声速值比普通聚乙烯(polyethylene,简称PE)单丝均有提高,其内部生成了串晶结构;SRPE单丝断裂强度、结节强度和结强损失率比普通PE单丝分别提高了12.75%、4.82%和12.69%,而断裂伸长率降低了27.72%。结论可供渔具设计及网线材料选配时参考。 相似文献
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Poultry coccidiosis is the major parasitic disease of poultry and, until now, no recombinant vaccine has been developed. Short oligodeoxynucleotides (ODNs) containing unmethylated CpG motifs (CpG ODNs) have been shown to be effective immunoprotective agents and vaccine adjuvants in mammalian systems. Their use in poultry to protect against intracellular parasites has not been reported to date. The present work investigated the effects of CpG ODN treatment on host susceptibility to Eimeria infection in two chicken strains with different genetic background, SC and TK. The data show that CpG ODN enhanced the birds' resistance to coccidiosis in a normally susceptible chicken strain (TK), as shown by reduced oocyst shedding and improved weight gain. CpG treatment had a differential effect on body weight gains and serum antibody responses, depending on the chicken strain and ODN dose, delivery route, and backbone. This study shows for the first time that CpG ODNs could be used as immunoprotective agents in Eimeria-infected chickens to enhance resistance to the pathogen and improve performance. Future research is needed to optimize their use alone and as vaccine adjuvants that may lead to better and more efficient vaccine applications. 相似文献
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