基于CNKI和PubMed数据库的双歧杆菌研究文献分析

目的统计分析国内外已发表的与双歧杆菌相关的期刊文献,了解其中的研究热点与发展趋势,为相关科研工作者提供参考。方法研究资料来源于CNKI和PubMed数据库,应用文献计量学的方法对两个数据库所收录的双歧杆菌相关文献进行分析。结果截至2018年8月15日,CNKI和PubMed分别收录了9277和5130篇相关文献。在数量上,国内外对双歧杆菌的研究都从20世纪90年代开始快速增长。从学科分布和关键词来看,中外研究共同关注了消化道疾病和儿科学,同时中外研究侧重点又有明显的差异。国内研究机构参与发表在国际杂志上的文章数量较多,但是其中作为第一发表单位的文章数量偏少。结论双歧杆菌相关的基础与应用研究还有许多需要深入和拓展的方面,研究者应当在相关领域进行实质性突破。     

Terrestrial ecologists ignore aquatic literature: Asymmetry in citation breadth in ecological publications and implications for generality and progress in ecology

The search for generality in ecology should include assessing the influence of studies done in one system on those done in other systems. Assuming generality is reflected in citation patterns, we analyzed frequencies of terrestrial, marine, and freshwater citations in papers categorized as terrestrial, marine and freshwater in high-impact “general” ecological journals. Citation frequencies were strikingly asymmetric. Aquatic researchers cited terrestrial papers ~ 10 times more often than the reverse, implying uneven cross-fertilization of information between aquatic and terrestrial ecologists. Comparisons between citation frequencies in the early 1980s and the early 2000s for two of the seven journals yielded similar results. Summing across all journals, 60% of all research papers (n = 5824) published in these journals in 2002–2006 were terrestrial vs. 9% freshwater and 8% marine. Since total numbers of terrestrial and aquatic ecologists are more similar than these proportions suggest, the representation of publications by habitat in “general” ecological journals appears disproportional and unrepresentative of the ecological science community at large. Such asymmetries are a concern because (1) aquatic and terrestrial systems can be tightly integrated, (2) pressure for across-system understanding to meet the challenge of climate change is increasing, (3) citation asymmetry implies barriers to among-system flow of understanding, thus (4) impeding scientific and societal progress. Changing this imbalance likely depends on a bottom-up approach originating from the ecological community, through pressure on societies, journals, editors and reviewers.     

Extinction debt in fragmented grasslands: paid or not?

Fragmentation of grasslands and forests is considered a major threat to biodiversity. In the case of plants, the effect of fragmentation or landscape context is still unclear and published results are divergent. One explanation for this divergence is the slow response of long‐lived plants, creating an extinction debt. However, this has not been empirically confirmed. In this study, data were compiled from broad‐scale studies of grasslands from throughout the world that relate plant diversity to fragmentation effects. Only seven studies from northern Europe, out of a total 61, gave any information on actual habitat fragmentation in time and space. In landscapes with >10% grassland remaining, present‐day species richness was related to past landscape or habitat pattern. In landscapes with <10% grassland remaining, in contrast, plant species richness was more related to contemporary landscape or habitat pattern. Studies from landscapes with >10% grassland remaining supported the concept of an extinction debt, while studies from more fragmented landscapes did not provide any evidence of an extinction debt. In order to make generalisations about historical legacies on species diversity in grasslands it is important to consider a range of highly transformed landscapes, and not only landscapes with a high amount of grassland remaining.     

Ezenwa-Ohaeto: Chants and the Minstrel

Ezenwa-Ohaeto’s life encapsulates what the critic and novelist Isidore Okpewho has described as the “dignity of intellectual labour.” This becomes clear as we take into consideration, the range of his production as a poet, scholar, and occasional journalist. Ezenwa-Ohaeto’s work grapples with a vast range of areas of specifically Nigerian literature and culture in the 20th century, but in general with the literature of the postcolonial world as they have come to express distinct, recognizable moral and aesthetic values. His untimely death in 2005 therefore, has implication for the study of this literature, particularly because it marks the closure of the questic imagination of a poet/scholar whose interventions were critical in the formation of the critical values of contemporary African writing. This paper examines Ezenwa-Ohaeto’s contributions in the light of this, and puts in some perspective, aspects of his life and work, and its implications in the formal canon that he helped to shape and stabilize.     

Stimulating factors for regulation of osteogenic and chondrogenic differentiation of mesenchymal stem cells

Mesenchymal stem cells (MSCs), distributed in many tissues in the human body, are multipotent cells capable of differentiating in specific directions. It is usually considered that the differentiation process of MSCs depends on specialized external stimulating factors, including cell signaling pathways, cytokines, and other physical stimuli. Recent findings have revealed other underrated roles in the differentiation process of MSCs, such as material morphology and exosomes. Although relevant achievements have substantially advanced the applicability of MSCs, some of these regulatory mechanisms still need to be better understood. Moreover, limitations such as long-term survival in vivo hinder the clinical application of MSCs therapy. This review article summarizes current knowledge regarding the differentiation patterns of MSCs under specific stimulating factors.     

A systematic map of ecosystem services assessments around European agroforestry

Agroforestry offers proven strategies as an environmentally benign and ecologically sustainable land management practice to promote ecosystem services. In this literature review, we systematically consider the agroforestry and ecosystem services literature with the aim to identify and catalogue the knowledge field and provide the first systematic synthesis of ecosystem services research in relation to European agroforestry. We reviewed 71 scientific publications from studies conducted in farmland and forest ecosystems with various types of agroforestry management. Each publication was systematically characterized and classified by agroforestry practice and research approach in order to provide an insight into the current research state in addressing ecosystem services (including methods, indicators, and approaches). Spatial distribution of the case study sites in Europe was also explored. In addition, typical clusters of similar research approaches were identified.The results show that ecosystem service assessment of European agroforestry is currently focused on the spatially extensive wood pastures in the Mediterranean, Atlantic, and Continental agricultural mosaic landscapes. A specific emphasis has been on regulating, supporting, and provisioning services, such as provision of habitat and biodiversity, food, climate regulation, fibre, and fuel, and the consideration of cultural services has been largely limited to aesthetic value. There is a bias to biophysical and monetary research approaches. The majority of the studies focus on quantitative methods and biophysical field measurements addressing the assessment of only one or two services. Monetary approaches have been applied in less than one fifth of the studies but form a distinctive group.Our results highlight gaps and biases in the ecosystem service research agenda within agroforestry based on which we conclude that research should aim to diversify from the biophysical and monetary approaches, towards a wider variety of approaches, especially socio-cultural, and a wider coverage of ecosystem services. Stronger consideration of stakeholder participation and introduction of spatially explicit mapping are also important key actions. We make suggestions to advance the promise of ecosystem services provision from European agroforestry in decision making including various actors, stakeholders, and institutions, with strong links to policy processes, such as the EU Biodiversity Strategy and Common Agricultural Policy.     

染色体三维结构重建方法研究

染色体三维结构重构问题是近年生物领域中基因组学的热点研究问题,是以二维交互频率数据为基础来预测其三维空间结构。最新相关实验表明染色质的三维空间结构对于基因表达、调控等方面都具有重要意义。而Hi-c数据能利用染色质交互信息形成二维接触矩阵重构出染色体三维结构。本综述以染色体三维结构重建方法为研究对象,通过对染色体三维结构重建方法进行比较分析,综述了目前基于Hi-c数据在染色体三维结构重建中的经典方法,系统介绍了染色体三维结构重建技术的发展脉络,以促进染色体三维结构重建的进一步研究。     

中国灵长类文献纵览

把1870-2001年来自美国"现代灵长类文献题录数据库"、"维普中文数据库"及"中国灵长类研究文献题录"的资料按4个时期(I:1870-1949;Ⅱ:1950-1965;Ⅲ:1966-1977;Ⅳ:1978-2001)分类整理.此外,使用了"科学引文数据库(扩展版)".结果如下:(1)1870-2001年共有20 52篇文献,2个文献数量高峰分别出现于1950-1965和1978-2001年;科研部门所发表的论文占54.2%,并随时间而增加;而国外部门则随之减少.(2)2 052篇文献中,超过9%的文献为SCI所收录,其中1966-1977年被SCI收录的文献百分比最高;在全部被SCI收录的文献中又以科研部门的占优势(59.1%);但国外部门则以其30.1%的文献被SCI收录而领先.(3)统计了灵长类研究9个领域文献百分比及其变化,其中1978-2001间生态学和行为、神经生物学、繁殖和饲养快速发展;化石灵长类、形态学和解剖学减少;分类及分布、细胞及分子进化显得不甚突出;在第Ⅱ时期和第Ⅳ时期疾病防治研究相当多;保护生物学得到越来越多的关注.第Ⅳ时期作者数量最多,但每个作者的文献平均数却不如第Ⅰ时期.一般地说,在SCI收录的作者中以中国作者居多,但在第I时期唯一被SCI收录的作者则是一名外国学者;在第Ⅲ时期外国作者占被收录作者数的60%.