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31.
O. P. Onishchuk N. I. Vorobyov N. A. Provorov 《Applied Biochemistry and Microbiology》2017,53(2):131-139
The most recent data on the system of cmp (competitiveness) genes that determine the nodulation competitiveness of rhizobial strains, i.e., the ability to compete for nodule formation in leguminous plants, is analyzed. Three genetic approaches for the construction of economically valuable strains of rhizobia are proposed: the amplification of positive regulators of competitiveness, the inactivation of the negative regulators of this trait, and the introduction of efficient competitiveness factors into strains capable of active nitrogen fixation. 相似文献
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Macro- and microevolution of bacteria in symbiotic systems 总被引:1,自引:0,他引:1
Using the examples of diverse interactions among prokaryotes and eukaryotes, the relationships between molecular and population mechanisms of evolution of symbiotic bacteria are addressed. Their circulation in host-environment systems activates microevolutionary factors that direct combinative or reductive genome evolution in facultative, ecologically obligatory, and genetically obligatory symbioses. Due to intense systemic intra-genome rearrangements and horizontal gene transfer, two types of gene systems evolve in these bacteria: (1) controlling the pathogenesis-like processes of host recognition and penetration and (2) responsible for mutualistic interactions that are related to nitrogen fixation and its transfer to the host. The evolution of gene systems of type 1 is directed by individual (Darwinian, frequency-dependent) selection, which is responsible for gene-for-gene interactions between the partners. In the evolution of the type 2 systems, group (interdeme, kin) selection plays the key role, being responsible for the development of bacterial traits beneficial for the host. Using the legume--rhizobia symbiosis as an example, it is shown that evolution of mutualism can be described in terms of biological altruism, whose regularities are common for intraspecific and interspecific relationships. Macroevolutionary rearrangements of bacterial genomes result from the structural changes in their populations, wherein various selection modes are combined with stochastic processes (genetic drift, population waves) induced in the symbiotic systems. 相似文献
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JF Yuan SJ Zhang O Jafer RA Furlong OE Chausiaux CA Sargent GH Zhang NA Affara 《BMC microbiology》2009,9(1):246
Background
Pseudorabies virus (PRV) is an alphaherpesviruses whose native host is pig. PRV infection mainly causes signs of central nervous system disorder in young pigs, and respiratory system diseases in the adult. 相似文献38.
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V. V. Kopat E. R. Chirak A. K. Kimeklis V. I. Safronova A. A. Belimov M. R. Kabilov E. E. Andronov N. A. Provorov 《Russian Journal of Genetics》2017,53(7):766-774
Many bacteria belonging to the order Rhizobiales have fixNOQP genes which encode cytochrome oxidase with high affinity to oxygen required for oxidative phosphorylation in microaerophilic conditions. There is one copy of the identified fixNOQP operon in ancestral forms of rhizobia (Bradyrhizobium), as well as in their putative evolutionary predecessors (bacteria related to Rhodopseudomonas). At the same time, forms deeply specialized in symbiosis (Rhizobium leguminosarum, Sinorhizobium meliloti) have multiple (2–3) copies, some of them have a high similarity (>90%) to fixNOQP genes of Bradyrhizobium and Rhodopseudomonas, and others have only 30–50% similarity. Two divergent copies fixNOQP are detected in Tardiphaga, which is a representative of the Bradyrhizobiaceae family, lacking the ability to fix N2 (lack of nif genes encoding the synthesis of nitrogenase) and to induce the formation of nodules on legumes roots (lack of nod genes encoding the synthesis of signal Nod factors activating symbiosis development). The presence of Tardiphaga in nodule bacterial communities from a range of legumes, including Vavilovia formosa (relic representative of the tribe Fabeae, for which R. leguminosarum bv. viciae is the main microsymbiont), suggests that the ancestral gene duplication and subsequent divergence of fixNOQP operon in bacteria related to Tardiphaga opened the possibility of wide dissemination of functionally different copies of this cluster among symbiotically active forms of Rhizobiales. It is possible that the acquisition of fixNOQP genes determines adaptation of bacteria to microaerophilic niches not only in plants nodules but also in their environment (the rhizosphere, rhizoplane, internal portions of soil aggregates). 相似文献
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内蒙古草原人类福祉与生态系统服务及其动态变化——以锡林郭勒草原为例 总被引:1,自引:0,他引:1
以锡林郭勒盟为研究区域,建立人类福祉评价指标体系,通过牧户问卷调查了解牧户对草原生态系统服务和福祉变化的认识,结合当地的自然环境、生态环境和社会经济等多方面的多年统计数据,采用专家打分法对牧民各福祉指标打分,对2001年和2010年牧民福祉变化进行了评估和分析。结果表明:收入、道路覆盖率、农村合作医疗保险和文化教育方面对牧民福祉变化贡献最大;生产资料持续供给能力下降是导致收入减少的主要方面;旗县的犯罪率,环境空气质量,饮食结构,离婚率等是导致牧民福祉下降的主要方面。有关研究结果为提高锡林郭勒盟人类福祉、生态保护和区域可持续发展政策制定提供科学依据。 相似文献