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991.
Nature's Concept. The ‘New Agriculture’ amidst Ecology,Economy and the Demythologization of the Gene
From worldwide discussions about the limits of agriculture has arisen a powerful vision of sustainable development. Phrases like ‘limitation’, ‘sustainability’, ‘sufficient supply’, ‘fair distribution’ and ‘productivity of resources’ are no longer hindrances but guidelines for a fairer and safer world. ‘Nature's Concept' focuses on biological and ecological principles. On this basis, criteria of action have to be defined in order to determine long‐term economic consequences of agri‐production. The costs of destruction of natural resources, such as reduction of genetic resources, changes to the world climate and soil degradation, are inestimably large. The long‐term effects show the real substance of the agri‐shift and the demands on research. The solution for sustainable agriculture is more than ever a scientific development of ‘tools’ for a sensible management of resources. Gene technology may be an option to reduce the ecological risks of agriculture, especially those of devastating land use. For this purpose, new education programmes with international links and interventions by states are crucial in order to solve conflicts when short‐term interests interfere with long‐term ecological values. The international agri‐centres could have a further impact to guarantee access to new techniques for all countries. Thus agriculture could finally become a major pillar in a fair world order. 相似文献
992.
D. U. Han C. Choi J. Kim W.‐S. Cho H.‐K. Chung S.‐K. Ha K. Jung C. Chae 《Zoonoses and public health》2002,49(7):346-348
The in vitro susceptibilities of 128 isolates of east1+Escherichia coli from pre‐weaned and post‐weaned pigs with diarrhoea were tested with nine commonly used anti‐microbial agents by an agar dilution minimal inhibitory concentration (MIC) procedure according to National Committee for Clinical Laboratory Standards guidelines. For the isolates from pre‐weaned and post‐weaned pigs, most of them were susceptible to low concentrations (MIC90) of tetracycline (4 and 2 μg/ml), ceftiofur (2 and 2 μg/ml), and colistin (4 and 2 μg/ml). Marked resistance was found in others. 相似文献
993.
994.
紫花苜蓿自然株高变量分析 总被引:5,自引:0,他引:5
测定了9个紫花苜蓿品种生长高峰期的自然株高,统计分析结果表明,紫花苜蓿6-9周龄生长高峰期,各品种平均自然株高与株龄间呈非常显著(P<0.01)或显著正相关,线性回归方程估测相对误差除Ranger大于5%外,其余线性回归方程估测相对误差均小于5%。第9周龄的Travois和皇后苜蓿平均自然株高显著不显著。第9周龄的Travois和皇后苜蓿平均自然株高显著(P<0.05)高于对照品种敖汉苜蓿平衡自然株高,其余各参试品种与对照品种敖汉苜蓿比较,平均自然株高株不显著。第9周龄平均自然株高排序前4位的品种依次为Travois, 皇后苜蓿,Ranger,Baker。 相似文献
995.
996.
Spike glycoprotein cleavage recognition site analysis of infectious bronchitis virus. 总被引:13,自引:0,他引:13
The spike glycoprotein of infectious bronchitis virus (IBV), a coronavirus, is translated as a precursor protein (So), then cleaved into two subunits (S1 and S2) by host cell serine proteases. In this study, we compared the cleavage recognition site of 55 IBV isolates to determine if the cleavage recognition site sequence, which consists of five basic amino acid residues, correlates with host cell range, serotype, geographic origin, and pathogenicity as it does in orthomyxoviruses and paramyxoviruses. The most common cleavage recognition site observed (33 of 55 viruses) was Arg-Arg-Ser-Arg-Arg, representing at least 11 different serotypes. Thus, cleavage recognition site does not appear to correlate with serotype. We also determined that cleavage recognition site sequence does not correlate with pathogenicity because attenuated and pathogenic isolates (different passages of the same virus) contain identical cleavage recognition site sequences. In addition, nephropathogenic strains had the same cleavage recognition site sequence as many nonnephropathogenic isolates. Cleavage recognition site sequence does correlate with viruses in different geographic regions, which may be an important characteristic to examine in epidemiologic studies. An IBV monoclonal antibody neutralization-resistant mutant (NR 18) had an unusual substitution of Ile for Arg at the fourth position, giving the sequence Arg-Arg-Ser-Ile-Arg, which likely prevents cleavage and, thus, destroys the conformationally dependent monoclonal antibody binding epitope. Six residues on the amino-terminal side of the cleavage recognition site are conserved in 31% of the isolates and consist of only one or two basic amino acids. Thus, the number of basic residues around the cleavage recognition site does not appear to correlate with increased cleavability, host cell range, and increased virulence as it does with envelope glycoproteins in orthomyxoviruses and paramyxoviruses. 相似文献
997.
Chin-Cheng Huang Fan Lee Wen-Jeng Tu Shu-Hwae Lee Ten-Shiang Huang Yeou-Liang Lin Ming-Hwa Jong Shih-Yuh Lin 《Veterinary microbiology》2002,84(4):317-326
The O/Taiwan/99 foot-and-mouth disease virus (FMDV), a South Asian topotype of serotype O, was introduced into Taiwan in 1999. The Chinese yellow cattle infected by the virus did not develop clinical lesions under experimental and field conditions. A blocking enzyme-linked immunosorbent assay (ELISA) kit with the 3AB antigen, a polypeptide of FMDV non-structural (NS) proteins, was used to evaluate the development and duration of anti-3AB antibodies, proving active viral replication, in the Chinese yellow cattle. The specificity of the assay was 99%, as was established with negative sera from regularly vaccinated and from na?ve cattle. The sensitivity tested with sera from naturally infected animals was approximately 64% and it was lower than that obtained by serum neutralization (SN) test. Under experimental infection, the Chinese yellow cattle developed lower anti-3AB antibodies than that developed in other species. Duration of anti-3AB antibodies was traced in two herds of naturally infected animals, indicating that anti-3AB antibodies persisted for approximately 6 months after outbreaks. On the basis of this study, we propose that the Chinese yellow cattle may have natural resistance, which limits viral replication and reduces the development of anti-3AB antibodies. 相似文献
998.
999.
1000.
随着中国正式加入世贸组织,利率市场化改革已势在必行。之前,央行已制定出了利率市场化的大体框架并分步实施。当前流行于各类刊物的一些观点对利率市场化含义的理解尚不够准确。流行观点依据新老自由主义理论,强调市场“均衡利率”水平的重要性,忽略了利率结构问题。所谓的“均衡利率”实际上是不存在的,利率市场化改革的真实含义应当是:由中央银行决定基准利率水平,由市场决定利率结构。在银行业引入竞争机制是必要的前提。参9 相似文献