Subjects: Digital Publishing >> New Media submitted time 2023-10-08 Cooperative journals: 《中国传媒科技》
Abstract：媒体融合经过多年的发展,已经进入了"深度融合"的下半场。在新的形势下,广电新闻编辑肩负着推动广播电视媒体深入融合的重要任务,广电媒体的转型在本质上就是编辑的转型。本文分析了融媒体时代广电新闻编辑工作表现出的新特点和融媒体时代对广电新闻编辑的职业要求,提出了广电新闻编辑在融媒体时代下的转型策略,希望能够为广电行业的融合发展做出一些贡献。
Subjects: Library Science，Information Science >> Library Science submitted time 2023-07-26 Cooperative journals: 《图书情报工作》
Abstract： [Purpose/significance] A wide variety of topic models has been developed with improved algorithm. This paper aims to study the research advances, generation process and algorithm of citation based topic models. Additionally, we discuss the application in the text of academic articles and research areas in the future.[Method/process] Based on the data of Web of Science and CNKI database, we collected articles of citation based topic models. In these articles, we selected several representative articles after manual interpretation to analyze the generative process, parameter estimation and inference methods in these citation based topic models.[Result/conclusion] Currently, there are mainly three types of citation based topic models. This includes the topic models which focus on the topic-citation distribution, while other topic models mainly study the relationship between the citing documents and the cited documents. Besides, citation context based topic models are also available. Additionally, more complete topic content can be detected after introducing citation information into the topic models. Moreover, most of the models are the variants of LDA and PLSA. In future, incorporating citation context information into topic models, improving the inference methods and applying the models are some of the future directions.
Subjects: Biology >> Botany >> Applied botany submitted time 2023-07-13 Cooperative journals: 《广西植物》
Abstract： In order to explore the species and population distribution of endophytic fungi in Camellia luteoflora, as well as their inhibitory effects on plant pathogenic fungi, this study used tissue separation method to isolate and purify endophytic fungi in C. luteoflora. These fungi were identified based on morphology and molecular biology, and their diversity was evaluated through statistical analysis. The strains with antibacterial activity were screened out by the plate confrontation method. The results were as follows: (1) A total of 261 strains of endophytic fungi were isolated from 324 C. luteoflora tissue samples, belonging to 1 phylum, 5 classes, 9 orders, and 22 genera. The dominant genera were Colletotrichum, Diaporthe and Pestalotiopsis with isolation frequencies of 21.84%, 16.86% and 10.34%, respectively. (2) The distribution of endophytic fungi in Camellia luteoflora varied in different seasons. The highest number of strains was isolated in winter (72 strains, accounting for 27.59%), which belonged to 16 genera; 62 strains were isolated in spring, belonging to 13 genera; 59 strains were isolated in summer, belonging to 15 genera; and 68 strains were isolated in autumn, belonging to 13 genera. The Shannon-Wiener index (H′), Simpson index (D), evenness index (E), and richness index (M) were highest in winter. The similarity of endophytic fungal species between spring and winter was higher, and the similarity between summer and autumn was higher. (3) The distribution of endophytic fungi also varied in different parts of C. luteoflora. The stem had the most abundant endophytic fungi, with 102 strains (accounting for 39.08%) belonging to 15 genera; 61 strains were isolated from the roots, belonging to 10 genera; and 98 strains were isolated from the leaves, belonging to 15 genera. The Shannon-Wiener index, Simpson index, evenness index, and richness index were highest in the stems, and the endophytic fungal species in the leaves were most similar to those in the stems. (4) The plate confrontation results showed that among the 35 tested endophytic fungi, 26 endophytic fungi had inhibitory effects on at least one plant pathogen fungus, accounting for 74.29%, among which CJ-II-2, XY-V-3, QY-II-4, QJ-III-2 and DJ-I-2 had inhibitory effects on 8 plant pathogen fungi to varying degrees. XY-V-3 had the best inhibitory effect on 8 plant pathogenic fungi, and the inhibitory rate was higher than 50%. XY-V-3 and QJ-II-2 have higher inhibitory rate than 50% on 2 strains of pathogenic fungi in C. luteoflora, which had the potential to control disease of C. luteoflora. The diversity of endophytic fungi in C. luteoflora is rich, and Some of the strains have higher effect of inhibiting plant pathogenic fungi, which lay a foundation for the research and development of biological control products and the control of the disease of C. luteoflora.
Subjects: Library Science，Information Science >> Information Science submitted time 2023-04-01 Cooperative journals: 《图书情报工作》
Abstract： [Purpose/Significance] Emerging technology identification helps countries and enterprises to grasp the technological frontier, discover technological opportunities, seize market opportunities and create social value. This paper reviews the research progress of emerging technology identification, and provides a reference for the study of emerging technology identification. [Method/Process] On the basis of clarifying the concepts and characteristics of emerging technology, this paper introduced the identification methods of emerging technologies based on relational networks in detail, summarized the network nodes, network relationships and measurement indicators of emerging technology identification, and made recommendations for the future study of emerging technology identification. [Result/Conclusion] The identification methods of emerging technology based on relational networks include the methods based on citation relationships, co-occurrence relationships, and similarity relationships. The network nodes of emerging technology identification are mainly from papers and patents data. The existing indicator system includes bibliometric indicators and network structure characteristic indicators. In the future, the study of emerging technology identification can be improved from the aspects of enriching data sources, integrating network relationships and measurement indicators. At the same time, the exploration of fusion network of multi-source data and multiple relationships in emerging technology identification should be strengthened.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： Rural revitalization is a comprehensive revitalization of rural areas, including not only the material dimension, but also the cultural and psychological aspects. The revitalization requires systematic construction of social psychology as well as the participation and intellectual support from psychological perspectives. Therefore, this study illustrated the endogenous demands of rural revitalization for the construction of rural public psychological service system, analyzed the current social psychological status of rural residents and its effects on rural revitalization, and proposed strategies and suggestions on the construction of rural public psychological service system to support rural revitalization. The suggestions include: (1) Incorporating the rural public psychological service system in the top-level design of rural revitalization strategy; (2) Performing mental health promotion that is in line with rural reality and has local characteristics; (3) Organically embedding rural public psychological service into rural social governance; (4) Strengthening rural social psychology research and providing relevant academic support.
Subjects: Biology >> Botany >> Applied botany submitted time 2021-11-04 Cooperative journals: 《广西植物》
Abstract： To study the anti-inflammatory of chemical constituents from the rhizome of ethnomedicine Rosa roxbunghii. The chemical constituents of fresh R. roxbunghii rhizome were studied by phytochemical separation and purification technology, and their structures were identified through physicochemical properties and spectral data. The inflammatory model of RAW264.7 induced by lipopolysaccharide (LPS) in vitro was established. The cell viability was detected by MTT assay, the release of inflammatory factor NO in the cell culture medium was detected by Griess method and the anti-inflammatory activity of each compound was evaluated through the kit. The results were as follows: (1)Fifteen compounds were isolated and identified as kaji-ichigoside F1(1), rosamultin(2), euscaphicacid(3),β-D-glucopyranosyl-(2a→1b)-2a-O-β-L-arabinopyranosyl-(2b→1c)-2b-O-β-L-arabinopyranosyl-(2c→1d)-2c-O-β-L-arabinopyranosyl-(2d→1e)-2d-O-β-L-arabinopyranosyl-(2e→1f)-2e-O-β-L-arabinopyranoside(4),catechin(5), 3-O-methylellagic acid-4´-O-β-D-xylopyranoside(6), 3-O-methylellagic acid-4´-O-α-L- rhamnopyranoside (7), tormentic acid (8), betulinic acid (9), spinosic acid (10) , arjunic acid (11), β-Sitosterol (12), β-Daucosterol (13), α-tocopherol (14) and n-hexacosane (15). Compounds 4, 6 and 7 were isolated from R. roxbunghii for the first time. (2)The results of in vitro bioactivity showed that compounds 1-7 significantly inhibited LPS induced NO release from RAW264.7 in a dose-dependent manner; The IC50 were 25.07, 24.56, 17.65, 9.87, 16.67, 40.83 and 34.98 μmol·L-1, respectively (dexamethasone as positive control 22.46 μmol·L-1 ). Anti-inflammatory activity of compounds 1-7 were showed better, among which compounds 3, 4 and 5 were slightly better than dexamethasone. The results indicated that triterpenoids, ellagic acids, flavonoids and oligosaccharides from R. roxbunghii were the main effective components and verified its anti-inflammatory effect in folk application.
Subjects: Biology >> Botany >> Applied botany submitted time 2021-08-09 Cooperative journals: 《广西植物》
Abstract： In order to investigate the good genes, cultivate the main superior cultivars and discover phylogenetic relationships of Magnolia officinalis, M. officinalis subsp. biloba and M. hypoleuca, we compared the differences among the cp (chloroplast) genomes of three Magnolia species and performed a phylogenetic tree of 14 species. Illumina HiSeq platform was used to sequence and assemble the cp genome of M. hypoleuca. Then the cp genomes of three Magnolia species were annotated by online platform and performed with three Magnolia species cp gene cycles. Moreover, the cp genomes of other 11 Magnolia species were downloaded from the NCBI database and phylogenetic tree of 14 all species cp genomes was constructed based on NJ method. The results indicated that Clean Reads of M. hypoleuca were 19 791 019, and Q30 was 91.33%. The total length of cp genome of M. hypoleuca was 160 051 bp, its GC content was 39.2%, including 37 tRNA and 8 rRNA. Besides, there were respectively six and four more functional gene numbers of M. hypoleuca than the other two Magnolia species, which indicated it had stronger viability. Compared with the cp genome structure of three Magnolia species, it showed that three Magnolia species had similar IR, LSC and SSC structures, GC content and tRNA number, but there were differences in the type and number of coding genes, the number and structure of introns and exons. Besides, the differential functional genes of three Magnolia species were mainly located in LSC region and IR region, involving large ribosomal subunits, small ribosomal subunits and unknown functional genes groups. Furthermore, based on NJ phylogenetic tree, M. hypoleuca was closely related to M. officinalis subsp. biloba, next to M. officinalis. In this study, M. hypoleuca had more abundant cp genome structure, composition and variation characteristics, which was the molecular mechanism of its adaptation to low light and low temperature environment in high latitude area. And it will also provide strong guidance for molecular breeding of excellent Magnolia varieties.
Subjects: Environmental Sciences, Resource Sciences >> Other Disciplines of Environmental Sciences, Resource Sciences submitted time 2021-03-02 Cooperative journals: 《干旱区研究》
Abstract：客观地评价水文情势变化是进行河流生态修复和流域水资源综合管理的基础。改进RVA法将径流典型年份的变化纳入整体改变度的计算过程中，相对更全面地评价径流水文情势的变化。近几十年来黑河流域气候条件的发生显著变化，黑河上游河流水文情势的变化情况仍需进一步研究。以黑河上游为研究区域，应用M-K检验识别径流的突变年份，采用改进RVA法计算分析黑河上游河流水文情势变化。结果表明，黑河上游径流的突变年份为2002年，2002年前后分别以平水年和丰水年为主；采用RVA法计算的整体改变度为54.68%，而改进的RAV方法计算的整体改变度为74.62%，说明RVA法低估了黑河上游水文情势整体改变度；黑河上游径流水文情势变化主要包括：相比于1960—2002年，2003—2015年后各月平均流量均呈不同程度增加，但最小1日、3日、7日和最大7日流量减小，其余极端流量指标呈不同程度增加，高、低流量发生次数及历时变化微弱，流量平均增加率、减小率以及逆转次数均增加；采用改进的RVA法计算的黑河上游水文情势的整体改变度为74.62%，属于高度改变。气候变化是导致黑河上游水文情势高度改变的主要原因。
Subjects: Psychology >> Experimental Psychology submitted time 2019-03-08
Abstract： Selective attention plays an important role in processing relevant information and ignoring irrelevant distractors. The relationship between visual working memory (VWM) and visual selective attention has been extensively studied. VWM is a complex system consisting of not only visual maintenance functions, but also executive control functions. High load on visual maintenance functions drains the capacity for perception and prevents distractors from being perceived, while high load on executive control functions drains the capacity available for active control and results in increased processing of irrelevant distractors. There are two types of load in VWM: capacity load referring to the number of items to be stored, and resolution load emphasizing the precision of the stored representations. It has been found that these two types of load exert opposite effects on selective attention. However the mechanism underlying the effects of different types of VWM load on selective attention is still unclear. In the present study, four experiments were designed to investigate how different types of VWM load affect selective attention. Thirty-six participants were enrolled in Experiment 1, 2 and 3, respectively, and 14 participants were enrolled in Experiment 4. Participants were asked to perform both a VWM task and a visual search task. In the VWM task, participants had to retain colors in VWM to perform a change detection task. There were three levels of VWM load: baseline load, high-capacity load and high-resolution load. In the baseline load condition, participants were required to retain two colors and the change between the memory colors and the probe colors was large. In the high-capacity load condition, participants had to retain four colors and the change between the memory colors and the probe colors was also large. In the high-resolution load condition, participants had to retain two colors and the change between the memory colors and the probe colors was small. In Experiment 1 and 2, the visual search task was a Flanker task that was presented either in the periphery or in the center of the memory array. The Flanker task was presented with the memory array simultaneously in Experiment 1 and sequentially in Experiment 2. In Experiment 3, the visual search task was a Navon task. It was presented after the memory array and only in the center of the memory array. In Experiment 4, a Flanker task was presented after the memory array and only in the center of the memory array. EEG data during the memory interval were recorded by a 64-channel amplifier using a standard 10-20 system. The results showed that high-capacity load and high-resolution load reduced Flanker interference, compared with baseline load, when the VWM task and the Flanker task were presented simultaneously, regardless of whether the Flanker task was presented in the periphery or in the center of the memory array. High-capacity load and high-resolution load also reduced Flanker interference, compared with baseline load, when the VWM task and the Flanker task were presented sequentially and the Flanker task was presented in the periphery of the memory array. Compared with baseline load, high-capacity load increased Flanker interference and high-resolution load reduced Flanker interference when the VWM task and the Flanker task were presented sequentially and the Flanker task was presented in the center of the memory array. Under the high-capacity load condition, the Navon interference for attending to global level was larger than that for attending to local level; under the high-resolution load condition, the Navon interference for attending to global level was smaller than that for attending to local level. ERP results showed that relative to the baseline load condition, the high-capacity load condition elicited smaller N2, whereas the high-resolution load condition elicited larger N2. In conclusion, when the Flanker task is presented during encoding stage of VWM, high-capacity load and high-resolution load reduce interference. When the Flanker task is presented in the periphery of the memory array during maintaining stage of VWM, high-capacity load and high-resolution load reduce interference. These findings support the load theory of selective attention. However, when the Flanker task is presented in the center of the memory array during the maintenance stage, high-capacity load and high-resolution load lead to opposite effects. High-resolution load reduce interference, while high-capacity load increase interference. The underlying mechanism is that the different patterns of neural activity associated with the two types of VWM load may result in different distribution of cognitive control resources to selective attention.
Subjects: Biology >> Zoology submitted time 2018-12-25 Cooperative journals: 《动物营养学报》
Abstract：本试验旨在研究罗伊氏乳杆菌LR1对断奶仔猪血清生化指标和肠道营养物质转运载体mRNA表达的影响。选取144头初始体重为（6.49±0.01） kg的21日龄杜×长×大断奶仔猪，随机分为3组，每组8个重复，每个重复6头。对照组饲喂基础饲粮，抗生素组饲喂基础饲粮+100 mg/kg喹乙醇+75 mg/kg金霉素，罗伊氏乳杆菌组饲喂基础饲粮+5×1010 CFU/kg罗伊氏乳杆菌LR1。试验期为14 d。结果显示：1）与对照组相比，饲粮添加抗生素显著提高了血清葡萄糖（GLU）的含量（P<0.05），且显著降低了血清尿素氮（UN）的含量（P<0.05）。2）与对照组相比，饲粮添加罗伊氏乳杆菌LR1显著提高了十二指肠胃动素（MLN）和空肠胆囊收缩素（CCK）的mRNA表达量（P<0.05）；饲粮添加抗生素显著提高了十二指肠MLN的mRNA表达量（P<0.05）。3）与对照组相比，饲粮添加罗伊氏乳杆菌LR1显著提高了十二指肠Na+依赖性谷氨酰胺载体2（ASCT2）、阳离子氨基酸运载体1（CAT1）、小肽转运体1（PepT1）和空肠中性和碱性氨基酸转运载体（rBAT）以及空肠与回肠y+L氨基酸转运体1（y+LAT1）的mRNA表达量（P<0.05）；饲粮添加抗生素显著提高了空肠y+LAT1、CAT1、PepT1和空肠与回肠哺乳动物雷帕霉素靶蛋白（mTOR）的mRNA表达量（P<0.05）。4）与对照组相比，饲粮添加罗伊氏乳杆菌LR1显著提高了十二指肠小肠脂肪酸结合蛋白（I-FABP）、乙酰辅酶A羧化酶α（ACCα）、脂肪酸合成酶（FASN）和十二指肠与空肠脂肪酸结合蛋白3（FABP3）以及十二指肠、空肠与回肠过氧化物体增殖物激活受体γ（PPARγ）的mRNA表达量（P<0.05）；饲粮添加抗生素显著提高了空肠ACCα的mRNA表达量（P<0.05）。5）与对照组相比，饲粮添加罗伊氏乳杆菌LR1显著提高了空肠和回肠钠-葡萄糖协同转运蛋白1（SGLT1）的mRNA表达量（P<0.05）；饲粮添加抗生素显著提高了十二指肠SGLT1、钠-葡萄糖协同转运蛋白3（SGLT3）的mRNA表达量（P<0.05）。综上所述，饲粮中添加5×1010 CFU/kg罗伊氏乳杆菌LR1对断奶仔猪的肠道营养物质转运具有良好的促进作用，表现为促进断奶仔猪肠道物理消化和化学消化，促进小肽、氨基酸及脂肪酸吸收转运，增强脂肪酸的合成。罗伊氏乳杆菌LR1在替代猪饲用抗生素方面具有巨大潜力，可用于开发新型猪饲料抗生素替代物。
Subjects: Biology >> Zoology submitted time 2018-12-24 Cooperative journals: 《动物营养学报》
Abstract：本试验旨在研究饲粮添加丁酸梭菌对断奶仔猪生长性能、肠道结构和免疫功能的影响。选取（25±1）日龄、体重（6.24±0.32） kg的健康“杜×长×大”杂交仔猪360头，随机分为5个组，每组4个重复，每个重复18头猪。对照组饲喂基础饲粮，试验组分别饲喂在基础饲粮中添加250、500、1 000和2 000 mg/kg丁酸梭菌的试验饲粮。试验期30 d。结果表明：1）250和1 000 mg/kg丁酸梭菌添加组断奶仔猪的平均日采食量(ADFI)显著低于对照组（P0.05）。结果提示，25～55日龄断奶仔猪饲粮添加250～500 mg/kg丁酸梭菌可改善断奶仔猪肠道结构，增强机体免疫功能。
Subjects: Library Science，Information Science >> Information Science submitted time 2017-11-08 Cooperative journals: 《数据分析与知识发现》
Abstract：【目的】制定专题专利预警平台建设方案, 为长期的专题跟踪预警分析、专题数据再利用等工作提供一种解决途径。【方法】平台集成开源代码平台和工具(DSpace、OpenRefine、ECharts、VOSviewer 等), 实现对专题数据的存储、跟踪、分类、清洗、分析、管理等功能。【结果】选择极紫外光刻技术专题进行应用实践, 测试并解决实践过程中的细节问题, 验证专题专利预警平台的可行性和有效性。【局限】目前的专题专利预警平台数据处理全自动化、数据分析指标化、内容挖掘的关联实现等方面需要进一步优化。【结论】专题专利预警平台所实现的功能, 对于在技术研发生命周期内进行技术专利及时跟踪预警并分类管理有着现实的意义。
Subjects: Biology >> Zoology submitted time 2017-10-10 Cooperative journals: 《动物营养学报》
Abstract：本试验旨在探讨利用近红外反射光谱技术测定棉籽粕常规营养成分含量和蛋公鸡代谢能的可行性。从全国范围内收集76个不同产地、不同年份、不同加工方式的棉籽粕样品，测定其常规营养成分含量，并通过蛋公鸡强饲试验测定其表观代谢能和真代谢能。随机选取定标集（n=56）和外部验证集（n=20）样品，建立近红外定标模型。结果表明：1）不同来源棉籽粕的营养成分和蛋公鸡代谢能变异较大，变异系数为2.52%~84.75%，其中水分、粗脂肪、粗纤维、表观代谢能和真代谢能的变异系数超过10%；粗蛋白质、粗灰分和总能的变异系数分别为9.58%、9.81%和2.52%。2）水分、粗蛋白质、粗脂肪、粗纤维、粗灰分和总能的定标决定系数为0.923 5~0.975 8，交互验证决定系数为0.824 7~0.930 3，外部验证决定系数为0.879~0.896；表观代谢能和真代谢能的定标决定系数为0.969 0和0.926 8，交互验证决定系数为0.917 0和0.905 7，外部验证决定系数为0.911和0.892。因此，常规营养成分和代谢能的定标方程均可用于日常分析。
Subjects: Biology >> Bioengineering submitted time 2017-09-20
Abstract： Vitamin K2 (VK2) is a series of menaquinone compounds with isoprene side chains, which are represented by MK-n depending on the length of the side chains. Highly active VK2 is mainly synthesized by microorganisms and has the physiological function of preventing and treating diseases such as osteoporosis, hemorrhage, liver cirrhosis and Parkinson's disease. Flavobacterium is an important production strain and can synthesize a variety of VK2 homologs including MK4, MK5 and MK6. We found that by regulating the fermentation temperature, the type and yield of VK2 homologs synthesized by Flavobacterium can be controlled. In the range of 20~37℃, Flavobacterium sp. M1-14 grows best at 25℃, the biomass reaches 8.8 g/L, but the fermentation product is completely MK6, the yield is 13.9 mg/L, and the unit cell yield is 1.6 mg/L g. When the fermentation temperature is higher than 30°C, Flavobacterium can synthesize MK4, MK5 and MK6 at the same time. At 37°C, the yields of MK4 and MK5 are the highest, which are 1.6 mg/L and 1.7 mg/L, respectively, and the total amount of VK2 is 12.5 mg/L. At this time, the biomass was only 5.5g/L, and the unit cell yield was 2.3mg/g. In view of the difference in the optimum temperature for the growth of Flavobacterium cells and the synthesis of VK2 homologs, variable temperature fermentation was considered to increase biomass and VK2 production. After optimization of multiple factors, we developed a two-stage temperature change strategy with low temperature first and then high temperature, that is, fermentation at 25°C for 48 hours, and then fermented at 37°C for 96 hours, the VK2 yield reached 20.9 mg/L (among which MK4 was 2.1 mg). /L, MK5 is 2.3 mg/L, MK6 is 16.5 mg/L), the biomass is 8.8 g/L, and the unit cell yield is 2.4 mg/g. Then, on the 30L fermenter, we investigated the oxygen demand of fermentation at different temperatures by controlling the ventilation rate and rotation speed. It was found that at 25℃ and 37℃, the optimum kLa for VK2 synthesis by Flavobacterium fermentation was 360 h-1 and 60 h-1, respectively. A two-stage variable kLa control strategy was developed for the changes in the oxygen demand of bacteria during variable temperature fermentation. After optimization, the kLa was 360 h-1 in the first 24 hours of variable temperature fermentation, and the kLa was 60 h-1 in the next 120 hours. was 22.5 mg/L), which was 107% higher than the initial value, the biomass was 15.5 g/L, and the unit cell yield was 1.9 mg/g. The staged fermentation regulation strategy of changing temperature and kLa can change the type of homologues of Flavobacterium synthesizing VK2, significantly increase the production of VK2, and lay an optimized foundation for realizing the industrialization of VK2 bioproduction.
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. submitted time 2017-09-20
Abstract：维生素K2（VK2）是一类脂溶性甲萘醌类化合物，根据其侧链中异戊烯基单元个数的不同，可用Menaquinone-n (MK-n, n=1~14) 表示。研究表明，VK2具有促凝血、预防及治疗骨质疏松症、帕金森症及心血管疾病等生理功能。利用微生物发酵生产的VK2具有全反式侧链、生物相容性高等优势，作为食品和药品更易于被消费者接受。但是，其下游分离纯化过程中存在产物浓度低、成分复杂、纯化工艺繁琐、产品得率低等诸多问题，目前还鲜有高纯度VK2制备工艺的报道。 黄杆菌可以合成MK-5和MK-6等VK2同系物，本研究针对其发酵产物的特点，开发了一整套相应的分离纯化工艺。首先通过膜浓缩和离心的方法快速获得黄杆菌菌体，菌体经干燥后，采用甲醇进行固-液萃取，固-液比为4:1（ml/g），萃取时间为20分钟，连续萃取3次，获得的VK2甲醇萃取液的萃取得率可达99.1%以上。然后，通过大孔树脂吸附层析,以甲醇/二氯甲烷=1/1（V/V）为洗脱液，可获得纯度约为15%的VK2粗品；再经过分子筛层析，在高径比为255:15，二氯甲烷为流动相时，可获得纯度约为57%的VK2低纯度产品；之后，经过反相硅胶柱层析，分别以甲醇/二氯甲烷=9:1,6:1,3:1（V/V）依次进行梯度洗脱，即可分离并纯化各VK2的同系物，其HPLC纯度均达90%以上。最后采用冷却结晶的方法制得一系列淡黄色晶体。通过质谱、红外光谱及核磁共振氢谱检测，均符合相应的VK2光谱特征，确定其为MK-5和MK-6晶体。经HPLC检测，MK-5和MK-6晶体纯度分别达到98.0%和99.3%。经多次重复实验后，表明全套工艺稳定，产物回收率可以达到88%以上。各填料经过15次重复利用后，其对VK2的纯度及回收率无明显的影响。 本研究所建立的从黄杆菌发酵液中提取和纯化VK2的方法具有工艺简单、处理能力大、产品纯度及得率高等优点，其为实现VK2的生物制备及其产业化奠定了优化的基础。在整个的提取、纯化及结晶的过程中，只有两种有机溶剂被使用，这更有利于有机溶剂的回收利用和VK2的规模化生产。
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