企业并购中的商誉问题

对近年来在我国悄然兴起的企业并购浪潮进行了分析,指出在并购中产生的商誉受并购业务的会计处理方法以及众多的现实及潜在因素的影响,其采用的方法也需要进一步调整和完善。对商誉问题的正确认识和科学处理,有助于产权制度改革及社会资源的整体优化。     

“遗传印记”现象的研究

“遗传印记”现象是由于子代体内来自父母双方的等位基因一方表达、另一方沉默造成的,对该现象的研究是分子遗传学研究的新兴领域之一。目前,通过一些研究方法,对“遗传印记”的分子机制已有一定的认识,随着对“遗传印记”研究的逐渐深入,必将深化人们对遗传和生命本质的认识。     

Genomic perspectives in microbial oceanography

The global ocean is an integrated living system where energy and matter transformations are governed by interdependent physical, chemical and biotic processes. Although the fundamentals of ocean physics and chemistry are well established, comprehensive approaches to describing and interpreting oceanic microbial diversity and processes are only now emerging. In particular, the application of genomics to problems in microbial oceanography is significantly expanding our understanding of marine microbial evolution, metabolism and ecology. Integration of these new genome-enabled insights into the broader framework of ocean science represents one of the great contemporary challenges for microbial oceanographers.     

Detectable radio flares following gravitational waves from mergers of binary neutron stars

Mergers of neutron-star/neutron-star binaries are strong sources of gravitational waves. They can also launch subrelativistic and mildly relativistic outflows and are often assumed to be the sources of short γ-ray bursts. An electromagnetic signature that persisted for weeks to months after the event would strengthen any future claim of a detection of gravitational waves. Here we present results of calculations showing that the interaction of mildly relativistic outflows with the surrounding medium produces radio flares with peak emission at 1.4 gigahertz that persist at detectable (submillijansky) levels for weeks, out to a redshift of 0.1. Slower subrelativistic outflows produce flares detectable for years at 150 megahertz, as well as at 1.4 gigahertz, from slightly shorter distances. The radio transient RT 19870422 (ref. 11) has the properties predicted by our model, and its most probable origin is the merger of a compact neutron-star/neutron-star binary. The lack of radio detections usually associated with short γ-ray bursts does not constrain the radio transients that we discuss here (from mildly relativistic and subrelativistic outflows) because short γ-ray burst redshifts are typically >0.1 and the appropriate timescales (longer than weeks) have not been sampled.     

Genomic island variability facilitates Prochlorococcus-virus coexistence

Prochlorococcus cyanobacteria are extremely abundant in the oceans, as are the viruses that infect them. How hosts and viruses coexist in nature remains unclear, although the presence of both susceptible and resistant cells may allow this coexistence. Combined whole-genome sequencing and PCR screening technology now enables us to investigate the effect of resistance on genome evolution and the genomic mechanisms behind the long-term coexistence of Prochlorococcus and their viruses. Here we present a genome analysis of 77 substrains selected for resistance to ten viruses, revealing mutations primarily in non-conserved, horizontally transferred genes that localize to a single hypervariable genomic island. Mutations affected viral attachment to the cell surface and imposed a fitness cost to the host, manifested by significantly lower growth rates or a previously unknown mechanism of more rapid infection by other viruses. The mutant genes are generally uncommon in nature yet some carry polymorphisms matching those found experimentally. These data are empirical evidence indicating that viral-attachment genes are preferentially located in genomic islands and that viruses are a selective pressure enhancing the diversity of both island genes and island gene content. This diversity emerges as a genomic mechanism that reduces the effective host population size for infection by a given virus, thus facilitating long-term coexistence between viruses and their hosts in nature.     

家兔基因文库的建立

根据鸟枪法克隆基因的原则，建立了家兔总ＤＮＡ文库。为适应同位素标记探针法克隆筛选方法，建立了以人噬菌体为载体的文库。每个重组子携家兔基因组ＤＮＡ平均２０ｋｂ，共获重组噬菌体达１０＾６。以人生长激素ｃＤＮＡ为探针，采用噬菌斑原位杂交、斑点杂交和Ｓｏｕｔｈｅｒｎ杂交等操作，对以噬菌体为载体的文库进行了筛选和有效性验证。结果表明：（１）人生长激素与兔生长激素的ＤＮＡ存在相当的同源性，以人生长激素ｃＤＮＡ     

中外企业破产兼并的对比分析

破产兼并是企业市场竞争的必然结果。本文分别从法律依据、破产界限、破产程序和兼并动机、兼并历史、支付方式和效用等方面 ,对比分析中外企业破产兼并的不同。通过分析 ,希望对我国破产兼并工作有所启示     

Genomic approaches to studying the human microbiota

The human body is colonized by a vast array of microbes, which form communities of bacteria, viruses and microbial eukaryotes that are specific to each anatomical environment. Every community must be studied as a whole because many organisms have never been cultured independently, and this poses formidable challenges. The advent of next-generation DNA sequencing has allowed more sophisticated analysis and sampling of these complex systems by culture-independent methods. These methods are revealing differences in community structure between anatomical sites, between individuals, and between healthy and diseased states, and are transforming our view of human biology.     

蒲公英药材总DNA的提取

采用改良的CTAB法、SDS法、高盐低pH法提取蒲公英药材基因组总DNA,通过紫外吸收、琼脂糖凝胶电泳检测其纯度与浓度.结果表明,改良的CTAB法所得DNA纯度最高,电泳条带最清晰、完整性好,可作为RAPD,ISSR等分子生物学研究.     

有时间窗物流配送路径优化问题的混合并购算法

为了克服并购算法在求解有时间窗物流配送路径优化问题时局部最优的缺陷,提出了混合并购算法的构想.通过对原有并购算法中单个并购操作的改进,增加多个并购操作,提高了算法的收敛性.在建立有时间窗物流配送路径优化问题数学模型的基础上,构造了有时间窗物流配送路径优化问题的混合并购算法模型.在Solomon数据集上进行多次实验,获取了有时间窗物流配送路径问题的最优解或近似最优解.     

昆虫全基因组DNA的保存及提取

以蚂蚁、天牛、蝗虫等昆虫为实验材料,建立了75%酒精常温浸泡密封保存和福尔马林常温浸泡密封保存昆虫样品2~4周后进行全基因组DNA提取的方法。基因组DNA经紫外分光光度法(260 nm、280 nm)、琼脂糖凝胶电泳、PCR检测,结果表明:从两种方法保存的样品中均能提取到纯净完整的基因组DNA,适用于分子生物学实验。