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91.
The effective competition is an effective organizational form of the industry in modem market economy. It is a form accompanied with large - scale production and vigor competition. The analysis of effective competition has been the focus that people have paid close attention to it very much all the time. It is a basis of industrial policy, on the basis of the former research, the aufhors bring out 9 indexes according to the actual situation of our country, then take automobile trade as an example, we analyze the automobile trade with principal component. 相似文献
92.
通过遗传工程能够产生由两个基因共同作用而形成的雄性不育。一个可以是能够导致雄性不育的基因,另一个可以是该雄性不育基因的活化基因,它们共同存在的时候表现雄性不育。利用位点特异性重组和转基因技术能够将这两个基因安排在植物同源染色体的相同位置上表达,成为等位基因,而获得分别只具有其中一个基因的两转基因系。它们之间杂交,F1中两个基因同时存在,F1产生雄性不育而成为不育系。常规品系与此F1不育系杂交,在杂种植株中,这两个基因不能同时存在,所有植株育性恢复。利用光温敏核不育性,化学杀雄和人工去雄可解决此不育系繁殖问题。该雄性不育性利用方式优越,育种简便易行,能够满足对最佳组合选育的要求,且能够定向培育目标杂交组合。 相似文献
93.
94.
面粉品质性状与速冻水饺品质关系的研究 总被引:9,自引:2,他引:9
对7种面粉的化学成分、面团流变学特性等指标进行测定,详细分析了各项指标与速冻水饺品质的相关关系,得出适合生产速冻水饺的面粉的最佳特性指标。并通过比较分析对黑龙江省地产小麦粉生产速冻水饺的适用性进行评价。 相似文献
95.
The discretization of real values is always one of the key problems to be solved in the domain of machine learning for its great contribution to speeding up the followed learning algorithms, cutting down the real demand of algorithms on running space and time, and improving the clustering capability of the ultimate learning results. The basic characteristics and framework of discretization approaches based on rough set model are analyzed at first, then the different measurements of the importance of candidate cuts are discussed and researched. Two new heuristic algorithms are put forward to finally select the useful cuts from a candidate set. The selected cuts of the two algorithms will adequately maintain the discernible relation of information systems for their full considering the specialty of rough set, which perfectly embodies the advantages of this theory. Moreover, excellent discretization results may be expected through these heuristic algorithms. 相似文献
96.
97.
Reactions to eight isolates of Karnal bunt, Neovossia indica, collected from seven different locations in northern India were studied on 13 host lines, including cultivars and breeding lines of Triticum aestivum, Triticum durum and Triticosecale in all possible combinations. The incidence of Karnal bunt varied from zero in PBW 34 and PBW 248 with isolates Ni8 and Ni2, respectively, to as high as 66.8% in a highly susceptible cultivar WL 711 with isolate Ni5. The differences in disease incidence among cultivars and isolates were highly significant. All the isolates could be distinguished on the basis of differential reactions on one or more of the host lines. Even the most resistant lines of durum (PDW 215), triticale (TL 1210) and wheat (HD 29) could be distinguished by the differential disease reaction with one or more of the eight isolates. The cultivar-isolate interaction for disease score was highly significant, indicating the probable existence of a gene-for-gene relationship in this host-pathogen system. 相似文献
98.
A set of simple sequence repeat (SSR or microsatellite) markers was used to discriminate a collection of 33 Spinacia oleracea hybrid cultivars from seven different breeding stations all over the world. All SSR markers were genic microsatellite markers located in coding or non-coding regions of genes of known function. Cluster analysis based on 13 of the SSR markers showed that the spinach hybrids grouped into three clusters. The first two clusters consisted of European spinach types, which were well discriminated according to their origin from different breeding stations. The third cluster was a mixture of Asian as well as European types of spinach. Subclusters in this group did not reflect differences in morphology, earliness or company origin. The data show that genic microsatellites are a powerful tool for discrimination of spinach cultivars. 相似文献
99.
Jeffrey A. McNeely 《Euphytica》2006,148(1-2):5-15
Summary While the issue of invasive alien species has important biological components, economic factors such as global trade deserve
much greater attention for several reasons. First, virtually all of our planet’s ecosystems have a strong and increasing anthropogenic
component that is being fed by increasing globalisation of the economy. Second, people are designing the kinds of ecosystems
they find productive or congenial, incorporating species from all parts of the world through quicker and more efficient means
of transportation. And third, growing travel and trade, coupled with weakening customs and quarantine controls, mean that
people are both intentionally and inadvertently introducing alien species that may become invasive. The great increase in
the introduction of alien species that people are importing for economic, aesthetic, accidental, or even psychological reasons
is leading to more species invading native ecosystems, with disastrous results: they become invasive alien species (IAS) that
have significant deleterious effects on both ecosystems and economies. This paper examines some of the important non-biological
dimensions of the IAS problem, including historical, economic, cultural, linguistic, health, sociological, management, legal,
military, ethical, and political dimensions. These are addressed in terms of the causes, consequences, and responses to the
problem of IAS. These dimensions of IAS are fundamental, and successfully addressing the problem will call for greater collaboration
between different economic sectors and among a wide range of disciplines. The Convention on Biological Diversity, the negotiations
of the World Trade Organisation, and many other international agreements offer important opportunities for addressing the
complex global problems of IAS through improved international cooperation. 相似文献
100.
José F. Barbosa-Neto Carlos M. Hernández Louise S. O’Donoughue Mark E. Sorrells 《Euphytica》1997,98(1-2):59-67
Genetic progress through selection is directly related to the amount of variability present in the population and the quality
of genes contributed by the parents. Genetic relationships between lines were studied using DNA marker-based estimates of
genetic similarity. A statistical methodology using the width of a confidence interval was developed to determine the number
of probes to be surveyed and the precision in the estimation of genetic distance between pairs of cultivars. Precision was
affected by type of genetic distance used, the number of cultivars, and amount of genetic diversity present in the studied
group. The width of a (1-α)% confidence interval decreased as the number of RFLP fragments increased. Oat and wheat diversity
studies were used to illustrate the methodology.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献