学报发行应建立"问责制"

作为主办单位的“窗口”,学报的发行往往与编辑职能混于一体,没有单独设立相应机构,发行数量长期偏低。阐述了学报发行现状,指出发行量过低的危害,提出学报发行“问责制”设想:成立学报发行委员会,负责承担发行责任;成立学报发行部(室);举办学报发行研讨会或年会等。并就搞好“问责制”应注意的几个问题加以说明。     

动态载荷下基于声发射技术的杨木破坏过程检测

利用声发射检测和力学试验相结合的方法,研究山杨木材在动态载荷下的声发射演变过程;结合木材粘弹性特点,通过声发射参数分析研究在不同受力阶段木材的声发射特点.结果表明:1)声发射信号幅值不连续,是跃迁的;材料断裂前声发射信号的幅值和能量比断裂后小,在断裂点对应声发射信号幅值和能量的局部极大值.2)随时间和载荷的变化,声发射累计撞击数和累计能量增加快慢可以体现杨木在受力条件下的完全弹性、弹性为主的弹塑性共存、塑性为主的弹塑性共存3种状态.3)声发射率和幅值参数可以预测材料纤维开始断裂进入危险期的第一"临界点"和材料大量纤维断裂进入严重危险期的第二"临界点",如果继续加载材料将会破坏断裂.     

Approaches to Configuration Determinations of Flexible Marine Natural Products: Advances and Prospects

Flexible marine natural products (MNPs), such as eribulin and bryostatin, play an important role in the development of modern marine drugs. However, due to the multiple chiral centers and geometrical uncertainty of flexible systems, configuration determinations of flexible MNPs face great challenges, which, in turn, have led to obstacles in druggability research. To resolve this issue, the comprehensive use of multiple methods is necessary. Additionally, configuration assignment methods, such as X-ray single-crystal diffraction (crystalline derivatives, crystallization chaperones, and crystalline sponges), NMR-based methods (JBCA and Mosher’s method), circular dichroism-based methods (ECCD and ICD), quantum computational chemistry-based methods (NMR calculations, ECD calculations, and VCD calculations), and chemical transformation-based methods should be summarized. This paper reviews the basic principles, characteristics, and applicability of the methods mentioned above as well as application examples to broaden the research and applications of these methods and to provide a reference for the configuration determinations of flexible MNPs.     

基于NbS的北京市乔木林固碳能力分析

[目的]乔木林生物质碳汇是影响森林碳汇的重要组成部分,是一种自然的气候解决方案,在全球气候变化大背景下,森林的固碳潜力一直被广泛关注,本文以北京市为例,分析不同的林业活动对乔木碳储量的影响.[方法]采用北京市森林资源设计调查数据,利用IPCC材积源-生物量法估算北京市乔木林碳储量,分析了2009-2014年北京市在森林...     

Taxonomic and Bioactivity Characterizations of Mameliella alba Strain LZ-28 Isolated from Highly Toxic Marine Dinoflagellate Alexandrium catenella LZT09

Microalgae host varied microbial consortium harboring cross-kingdom interactions with fundamental ecological significance in aquatic ecosystems. Revealing the complex biofunctions of the cultivable bacteria of phycosphere microbiota is one vital basis for deeply understanding the mechanisms governing these dynamic associations. In this study, a new light-yellow pigmented bacterial strain LZ-28 was isolated from the highly-toxic and harmful algal bloom-forming dinoflagellate Alexandrium catenella LZT09. Collective phenotypic and genotypic profiles were obtained to confidently identify this strain as a new Mameliella alba member. Comparative genomic analysis showed that strain LZ-28 shared highly similar functional features with other four marine algae-derived M. alba strains in spite of their distinctive isolation sources. Based on the bioactivity assaying, the mutual growth-promoting effects between bacterial strain LZ-28 and algal strain LZT09 were observed. After the culture conditions were optimized, strain LZ-28 demonstrated an extraordinary production ability for its bioflocculanting exopolysaccharides (EPS). Moreover, the portions of two monosaccharides glucose and fucose of the EPS were found to positively contribute to the bioflocculanting capacity. Therefore, the present study sheds light on the similar genomic features among the selected M. alba strains, and it also reveals the potential pharmaceutical, environmental and biotechnological implications of active EPS produced by this new Mameliella alba strain LZ-28 recovered from toxic bloom-forming marine dinoflagellate.     

苹果采后加工碰撞损伤影响因素研究

针对苹果在清洗、分级和包装等采后加工过程中损伤率较高的问题,以红富士苹果为试验材料,利用自制的苹果跌落试验台,研究跌落高度、果实质量、碰撞材料对苹果碰撞损伤的影响.通过3因素3水平正交试验,分析试验因素对苹果碰撞损伤体积影响显著性;并通过试验确定苹果在2种碰撞材料下的碰撞损伤临界跌落高度.试验结果表明:影响苹果碰撞损伤...     

在体外模拟瘤胃发酵条件下N-乙酰-DL-蛋氨酸稳定性的研究

通过两个试验,研究在体外模拟瘤胃发酵条件下N-乙酰-DL-蛋氨酸的降解率。试验1:N-乙酰-DL-蛋氨酸在pH值6.5、温度为39℃的缓冲液中孵育9h,其降解率为3.3%。试验2:运用瘤胃体外发酵技术研究N-乙酰-DL-蛋氨酸不同添加量对pH值、氨态氮、微生物蛋白动态变化的影响。结果表明,添加0.4、0.6gN-乙酰-DL-蛋氨酸发酵3～6h,均能够显著降低体系的pH值;添加0.6gN-乙酰-DL-蛋氨酸发酵12h能够显著提高氨态氮的浓度;N-乙酰-DL-蛋氨酸在发酵过程中不影响微生物蛋白产量。以上结果显示,N-乙酰-DL-蛋氨酸在体外模拟瘤胃发酵的条件下可以稳定存在。     

高铜对雏鸡血清中含铜酶活性的影响

选用1日龄艾维茵肉鸡420只,随机分为7组,分别喂以对照日粮(Cu11mg/kg)、高铜日粮[Cu100mg/kg(Ⅰ组)、Cu200mg/kg(Ⅱ组)、Cu300mg/kg(Ⅲ组)、Cu400mg/kg(Ⅳ组)、Cu500mg/kg(Ⅴ组)、Cu600mg/kg(Ⅵ组)]6周。结果显示:与对照组相比,Ⅰ、Ⅱ组雏鸡血清铜蓝蛋白活性显著升高,Ⅴ、Ⅵ组显著降低(P<0.05或P<0.01),表明100mg/kg和200mg/kg的铜能显著提高雏鸡血清铜蓝蛋白活性,而铜高于500mg/kg时能使其活性降低;铜锌超氧化物歧化酶活性变化不明显(P>0.05)。     

天然气抗氧化刘的研究概况

按照美国食品药物管理局(FDA)定义,所谓抗氧化剂是指作为延滞因氧化所引起的劣变、酸败或变色的物质[1].     

2020年宁夏吴忠市畜间包虫病流行病学调查

为了解宁夏吴忠市畜间包虫病流行范围及防治效果,科学规范指导下一阶段包虫病防治工作,2020年对吴忠市5个县(市、区)采用基本情况调查、实验室抽样检测等方法进行了畜间包虫病流行病学调查.共检测犬粪样品1861份,犬细粒棘球绦虫感染阳性率为0.75％;抽检羊脏器4027份,棘球蚴感染率为0.22％,有3个县区检出感染;检测...