Submitted Date
Subjects
Authors
Institution
Your conditions: 刘磊
  • Research on strength parameters of asphalt mixture based on boundary effect theory

    Subjects: Mechanics >> Solid Mechanics submitted time 2023-06-21 Cooperative journals: 《应用力学学报》

    Abstract:
    To analyze the strength parameters and fracture characteristics of the asphalt mixture,after the offset distance was considered and an equivalent peak load was introduced,a modified boundary effect model was established based on the boundary effect(BE)theory.The different pre-crack three-point bending tests were carried out at 5 ℃,and the corresponding XFEM modeling was performed and validated by the load displacement curve from the tests.The tensile strength and fracture toughness were determined by the load peak obtained from test and numerical simulation.Finally the variation curve between the offset distance and load peak was inversed and fitted by the modified model solution.The results show there is little difference between the model solution and test data.It is proved that a modified boundary effect model not only overcomes the limitation of mixed fracture specimens application of the original BE model,but also provides a prediction method for determining the elastic and brittle fracture performance of asphalt mixtures.

  • Research on the Peer Review Mechanism of Registered Reports

    Subjects: Library Science,Information Science >> Information Science submitted time 2023-04-01 Cooperative journals: 《图书情报工作》

    Abstract: [Purpose/significance] The frequent "academic scandals" in recent years have posed new challenges to my country's scientific research review mechanism. The Registered Report that emerged in the open science movement can effectively improve the transparency of the research process and evaluation process, reduce the publication bias in the review process, and ensure academic rigor and scientific research quality due to its unique peer review mechanism, to put an end to academic fraud. The paper attempts to conduct an in-depth study of the peer review mechanism of registered reports, analyze and summarize its characteristics, in order to provide a reference for the innovative development and scientific improvement of peer review in my country.[Method/process] Comprehensive used of online research methods and content analysis methods to analyze the review process, review form, review efficiency, review ethics guidelines, reviewer expert database construction and other aspects of the registration report peer review. Explored the relationship between authors, reviewers, and editors in the peer review mechanism of registered reports and related rights, and summarized the characteristics of the peer review mechanism of registered reports.[Result/conclusion] The innovative features of the peer-review mechanism of registered research reports are mainly reflected in the following aspects:① The optimization of review process and standards:the new mode of peer-review for registered research is implemented twice, which is no longer only based on subjective judgment of experts, and the process of selection of review experts and treatment of expert opinions is scientific and reasonable;② The improvement of anonymity and interactivity:the diversification of peer review forms and the pursuit of maximum flexibility while maintaining basic checks and balances;③ The improvement of review efficiency:the parallel review information transmission mode, the regulation of Ming culture and the systematic supervision and punishment mechanism contribute to the high efficiency of peer review. The advanced features of the peer-review mechanism of registered research reports are as follows;① It establishes a strict and meticulous moral code system for reviewers;② Pay attention to the construction of the peer review expert database, and form a complete reviewer incentive mechanism.

  • Exploring the prospect of library resources construction for Registered Reports

    Subjects: Library Science,Information Science >> Library Science submitted time 2023-02-09

    Abstract: Purpose/Significance In the context of the development of open science and the paradigm change of scientific research communication, libraries, as important resource centers and information service institutions for scientific research activities, are faced with important tasks such as enriching the resource system and exploring new growth points for resource construction. As an emerging and highly valuable scientific research resource, it will be a strategic layout with practical significance for libraries to incorporate Registered Reports into their own resource system and develop library services based on them. Methodology/Process Using a combination of literature research method and web research method, we analyze in detail the necessity, possibility and feasibility of incorporating Registered Reports into the library resource system, summarize the existing practical experience abroad, and propose feasible strategies for incorporating Registered Reports into the library resource system. Results/Conclusions The incorporation of Registered Reports into the library resource system can effectively respond to the "reproducibility crisis" in the scientific community and better meet the new research communication needs under open science, which is an inherent requirement of the 14th Five-Year Plan of the library. It is an inherent requirement of the 14th Five-Year Plan of the Library. Scientific data, which is one of the fragments of Registered Reports, has become a mature collection resource, and Registered Reports have shown a positive development trend, which provides a possible reference for the integration of Registered Reports into the library resource system. Libraries can promote the value of Registered Reports through the TOP Guidelines, promote the establishment of a pre-registration platform, add "pre-registration librarians," provide pre-registration support services, build a collection of Registered Reports, and guide the management and application of Registered Reports based on the FAIR principles. The construction of resources for Registered Reports is carried out through the following ways.

  • 冻融作用下地下水浅埋区土壤盐分及离子变化特征

    Subjects: Geosciences >> Geography submitted time 2022-03-28 Cooperative journals: 《干旱区研究》

    Abstract:冻融作用是地下水浅埋区土壤盐渍化的重要原因之一,了解其对土壤盐分及离子变化的影响对土壤盐渍化防治具有重要意义。为探究冻融作用下土壤盐分及离子的分布及变化规律,以太谷均衡实验站地中蒸渗仪系统为试验设备,结合野外和室内试验分析了20202021年冻融期内6种不同地下水埋深下土壤剖面水分、可溶性盐分及离子含量的变化特征以及冻结层在冻融过程中对土壤盐分运移的影响,并采用灰色关联法分析了土壤含盐量与离子间的关联度。结果表明:(1)蒸渗仪土壤中以Na+、Ca2+、HCO-3 、SO2-4 及Cl-为主,土壤含盐量与Na+和HCO-3 极显著相关,与Ca2+、SO2-4 和Cl-显著相关。(2)冻结层在整个冻融过程中对于Ca2+和Cl-变化影响较小,对Na+,HCO-3 ,SO2-4 及土壤总盐分变化影响较大。当冻结层全部处于最大毛细水上升高度范围内时,冻结层起积盐作用;当冻结层未处于最大毛细水上升高度范围内时,冻结层对于盐分运移起阻碍作用。(3)土壤含盐量与地下水埋深之间呈反比关系。当地下水埋深为3.0 m时,土壤含盐量变化值远小于0.5~2.5 m埋深。该研究可为地下水浅埋区土壤盐渍化的防治提供理论依据。

  • 我国地基雷达观测月球的现状和研究进展

    Subjects: Astronomy >> Astrophysical processes submitted time 2021-03-30 Cooperative journals: 《天文研究与技术》

    Abstract:地基雷达天文观测可以提供太阳系天体目标的地形地貌、物理特征、轨道动力等信息。文章聚焦利用地基雷达天文技术开展月球观测的原理方法和科学意义,介绍了基于我国现有深空雷达上行装置、射电望远镜条件、以及非相干散射雷达等系统,初步开展的UHF频段和X频段的地基雷达观测月球试验。通过月球反射回波的信号处理,获得了延迟、多普勒频移等参数,得到了一致的与近表层物质密度相关的月面雷达反射率,并得到了月球的左右旋圆极化率,其反映了与波长同尺度的月球近表层结构。文章积累的数据处理经验将为我国的小行星预警、行星历表等地基雷达天文观测研究提供技术基础。

  • 空间VLBI数据记录格式RDF解析与数据解码

    Subjects: Astronomy >> Astrophysical processes submitted time 2019-11-13 Cooperative journals: 《天文研究与技术》

    Abstract: 空间VLBI由于基线更长,在相同观测频率下,可获得比地基VLBI更高的分辨率。我国正在推进空间VLBI科学与技术研究。俄罗斯RadioAstron空间VLBI项目于2018年结束,其成功经验可资借鉴。该项目采用不同于常规地面VLBI的专用数据格式RDF(RadioAstron Data Format)记录观测数据,利用配备的星载或地面上行氢原子频标提供频率基准,数据经采集量化后传输至地面站,打上时标并记录于硬盘。为处理RadioAstron数据,本文分析了RDF格式,完成了RDF数据解码及VLBI相关处理,然后对比分析了Mark5B、VDIF等地面VLBI通用数据格式和RDF格式的特点。这些工作将为我国未来空间VLBI数据格式设计与处理积累经验。

  • 非小细胞肺癌跳跃性 N2 淋巴结转移的临床病理特点

    Subjects: Medicine, Pharmacy >> Clinical Medicine submitted time 2019-02-25 Cooperative journals: 《协和医学杂志》

    Abstract:肺癌作为全球肿瘤致死的首要原因,其主要治疗方式,尤其对于早期非小细胞肺癌患者,手术治疗依然占主导地位,而淋巴结转移状态对于肺癌的分期、预后至关重要。跳跃性N2 转移比较常见,而且与患者的预后密切相关。本文主要归纳非小细胞肺癌跳跃性 N2 转移的临床病理特点及其生存预后等,期待为临床决策提供一定的指导。

  • 短期限饲对生长肉兔脂肪组织中脂质代谢的影响

    Subjects: Biology >> Zoology submitted time 2018-12-25 Cooperative journals: 《动物营养学报》

    Abstract:本文旨在研究短期限饲对生长肉兔脂肪组织中脂质代谢相关基因和相关信号通路的影响,阐明生长肉兔能量稳态的调节机制。试验选用40日龄、体重相近的伊拉肉兔40只,随机分为2组:对照组(自由采食组)和限饲组(饲喂量是对照组的70%左右),每组20个重复,每个重复1只兔,试验持续5 d。结果表明:1)与对照组相比,短期限饲显著降低了生长肉兔的日增重(P0.05)。2)与对照组相比,短期限饲显著降低了脂肪酸合成酶(FAS)、乙酰辅酶A羧化酶(ACC)、脂蛋白脂酶(LPL)的基因表达(P0.05)。3)与对照组相比,短期限饲对脂肪中甘油三酯(TG)的浓度和磷酸化的磷酸腺苷激活蛋白酶(AMPK)蛋白表达水平影响不显著(P>0.05)。综上,短期限饲可抑制生长肉兔脂肪组织中脂肪酸的合成,促进脂肪酸分解;PPARα和GPR41信号可能参与了生长肉兔脂肪组织能量稳态的调节。

  • 饲料粗纤维、中性洗涤纤维和酸性洗涤纤维残渣中各成分的研究

    Subjects: Biology >> Zoology submitted time 2018-12-24 Cooperative journals: 《动物营养学报》

    Abstract:本试验旨在研究饲料粗纤维、中性洗涤纤维和酸性洗涤纤维残渣中各成分。试验采用聚酯纤维筛网袋法测定了米糠、小麦麸、白三叶、枸树叶、全株玉米、全株小麦、毛苕子、兔配合饲料、高粱、燕麦秸、苜蓿、稻秸、小黑麦干草、皇竹草、芦苇、花生秧、大豆秸和稻壳粉18种饲料的粗纤维(CF)、中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)含量,测定了饲料CF残渣中半纤维素、纤维素、酸性洗涤木质素和酸不溶灰分的含量及回收率,同时测定了NDF和ADF残渣中半纤维素、纤维素、酸性洗涤木质素和酸不溶灰分的含量,研究了饲料中的CF、NDF和ADF残渣中各成分含量及CF和ADF之间的相互关系。结果表明:所测18种饲料中的纤维素在CF残渣中的回收率最高(71.28%~105.03%);饲料ADF含量(y1)和CF含量(x1)之间呈高度正相关:y1=1.507 1+1.211 5x1 (r=0.979 2,RSD=1.863 4,P<0.01);饲料ADF残渣中去除酸不溶灰分后的ADF含量(y2)和CF含量(x2)之间的相关性更高:y2=2.406 3+1.077 0x2 (r=0.990 5,RSD=0.962 4,P<0.01)。由此提出饲料中半纤维素和纤维素含量的准确测定计算方法,即半纤维素含量等于NDF含量(无酸不溶灰分)减去ADF含量(无酸不溶灰分);纤维素含量等于ADF含量(无酸不溶灰分)减去酸性洗涤木质素含量

  • 饲粮中添加艾叶粉对生长肉兔营养物质表观消化率、氮代谢和肌肉品质的影响

    Subjects: Biology >> Zoology submitted time 2018-12-20 Cooperative journals: 《动物营养学报》

    Abstract:本试验旨在研究饲粮中添加艾叶粉对生长肉兔营养物质表观消化率、氮代谢和肌肉品质的影响。试验选取160只35日龄的体重相近的商品伊拉肉兔,随机分成4组(每组40个重复,每个重复1只兔),分别饲喂艾叶粉添加量为0(对照组)、3%(替代对照组饲粮中1%的花生秧和2%的小麦麸)、6%(替代对照组饲粮中3%的花生秧和3%的小麦麸)、9%(替代对照组饲粮中4%的花生秧和5%的小麦麸)的饲粮。预试期7 d,正试期30 d。结果表明:饲粮中添加3%、6%和9%的艾叶粉对粗纤维(CF)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、木质素(ADL)、钙(Ca)、磷(P)的表观消化率以及食入氮、粪氮、尿氮、沉积氮、氮利用率、氮生物学效价均无显著影响(P>0.05);饲粮中添加3%和6%的艾叶粉对家兔饲粮的CP的表观消化率和可消化氮无显著影响(P>0.05),但饲粮中添加9%的艾叶粉显著降低了饲粮的CP的表观消化率和可消化氮(P0.05)。综合本试验测定指标,生长肉兔饲粮中艾叶粉的添加量不宜超过6%。

  • 饲粮碘添加水平对生长獭兔生长性能、屠宰性能、肌肉品质和皮张质量的影响

    Subjects: Biology >> Zoology submitted time 2018-12-20 Cooperative journals: 《动物营养学报》

    Abstract:本试验旨在研究饲粮碘添加水平对3~5月龄生长獭兔生长性能、屠宰性能、肌肉品质和皮张质量的影响。选用体重相近的健康3月龄獭兔200只,随机分为5组,每组40个重复,每个重复1只。各组分别饲喂在基础饲粮中添加0、0.2、0.4、0.8、1.6 mg/kg碘(以碘化钾的形式)的试验饲粮。预试期7 d,正试期53 d。结果表明:1)在初始体重(IBW)无显著差异(P>0.05)的前提下,饲粮碘添加水平对獭兔的终末体重(FBW)有显著影响(P<0.05),对平均日采食量(ADFI)有极显著影响(P<0.01),对平均日增重(ADG)和料重比(F/G)均没有显著影响(P>0.05);0.8 mg/kg组獭兔的ADG和ADFI最高,F/G最低。2)饲粮碘添加水平对獭兔的后腿肌肉率和红度值有显著影响(P<0.05),对前腿肌肉率有极显著影响(P<0.01),对全净膛率、背腰肌肉率和肌肉品质指标[pH、失水率以及肉色(亮度、黄度值)]均没有显著影响(P>0.05)。3)饲粮碘添加水平对獭兔的皮张面积、毛被白度和撕裂强度有极显著影响(P<0.01),且最大值分别在0.8、0.4和0.4 mg/kg组。饲粮碘添加水平对獭兔的皮张重量和皮板厚度有显著影响(P<0.05),对毛囊密度、毛被光泽度、毛被长度、撕裂断点厚度、抗张强度及规定负荷伸长率均没有显著影响(P>0.05)。综合本试验测定指标,3~5月龄生长獭兔饲粮适宜的碘添加水平为0.8 mg/kg(饲粮中碘的实测值为0.92 mg/kg)。

  • 一种基于ROEWA算子的改进CV模型用于乳腺超声图像分割

    Subjects: Biology >> Bioengineering submitted time 2018-03-15

    Abstract:基于区域的几何活动轮廓(Chan-Vese, CV)模型是乳腺超声图像常用的一种分割算法。但传统的CV模型不能满足乳腺超声图像分割精度高、速度快的要求。因此,文章提出了一种基于指数加权平均比率(Ratio of Exponential Weighted Average,ROEWA)算子改进的CV模型,用于乳腺超声图像中病灶区域的分割。首先,计算乳腺超声图像的ROEWA算子。其次,基于图像的ROEWA算子构建边缘指示函数,用于代替CV模型中的Dirac项。最后,去除平滑项,从而提高曲线演化的速度。实验结果表明,文章提出的算法不仅能提高分割的精度,而且能显著提高分割的速度。

  • 雷公藤甲素对佐剂关节炎肺功能降低大鼠Notch通路受体和配体基因表达的影响

    Subjects: Medicine, Pharmacy >> Preclinical Medicine submitted time 2017-12-07 Cooperative journals: 《南方医科大学学报》

    Abstract: Objective To investigate the effects of triptolide on Notch receptor and ligand expressions in rats with adjuvant-induced arthritis (AA). Methods Forty rats were randomly divided into normal control (NC) group, model (MC) group, methotrexate group and triptolide groups. Rat models of AA were established by an intradermal injection of 0.1 mL Freund's complete adjuvant into the right paw. Twelve days after the injection, the rats were treated with corresponding drugs for 30 days; the rats in NC group and MC group were given saline only. Paw edema volume (E), arthritis index (AI), pulmonary function, histomorphologies, and Notch receptor/ligand expression in the lung tissue were analyzed after the treatments. Results Compared with the NC group, E, AI, Notch3, Notch4, and Delta1 expressions in the lung tissues significantly increased while pulmonary function and pulmonary expressions of Notch1, Jagged1, and Jagged2 significantly decreased the model rats (P<0.01). Compared with the MC group, triptolide-treated rats showed significantly improved pulmonary functions, increased expressions of Notch1, Jagged1, and Jagged2 and decreased expressions of Notch3, Notch4, and Delta1 in the lungs (P<0.05, P<0.01); the therapeutic effect of triptolide was better than that of methotrexate. Conclusion Triptolide can reduce inflammatory reaction and immune complex deposition to improve joint and pulmonary symptoms in rats with AA possibly by up-regulating the expressions of Notch3, Notch4, and Delta1 and down-regulating the expressions of Jagged1, Jagged2, and Notch1.

  • Hi-B钢二次再结晶退火中异常长大Goss晶粒的三维形貌表征

    Subjects: Materials Science >> Materials Science (General) submitted time 2017-11-21 Cooperative journals: 《金属学报》

    Abstract:利用定量逐层研磨和计算机辅助重建及可视化技术,并结合电子背散射衍射(EBSD)技术,研究了Hi-B钢二次再结晶退火中异常长大Goss晶粒的三维形貌,并探讨了其长大规律和特征。研究表明,在三维尺度上, 异常长大Goss晶粒呈现“饼形”晶粒形貌,异常长大过程中遵循“饼形”长大规律,即处在次表层的二次再结晶核心在中间层快速长大取得尺寸优势后,反向沿厚度方向长大到样品表面,并在表面能的作用下继续沿板面方向异常长大,最终使得在板面方向的尺寸远大于厚度方向的尺寸;在Goss晶粒异常长大过程中,一些基体大尺寸晶粒由于尺寸优势会阻挡Goss晶粒长大,从而暂时保留在晶粒内部形成“岛状”晶粒。而在长大前沿,由于基体晶粒尺寸的不均匀性,特别是遇到一些大尺寸晶粒无法在短期内被吞噬掉,或者是两个异常长大的Goss晶粒相遇后造成某些方向长大停止,而一些基体晶粒被包裹进来成为“岛状”或“半岛状”晶粒,还有可能是不同取向晶粒晶界迁移率存在明显的差异性等方面的影响,使得Goss晶粒在某些方向长大受阻,从而表现出晶界前沿参差不齐,长大呈现典型的各向异性特征。

  • 饲粮中核黄素添加水平对生长獭兔肉品质、毛囊发育和免疫性能的影响

    Subjects: Biology >> Zoology submitted time 2017-10-23 Cooperative journals: 《动物营养学报》

    Abstract:本试验旨在研究饲粮中核黄素添加水平对生长獭兔肉品质、毛囊发育和免疫性能的影响。选择体重相近的3月龄獭兔160只,随机分为4组,每组40个重复,每个重复1只兔。各组分别饲喂在基础饲粮中添加0(对照)、3、6和12 mg/kg核黄素的饲粮。预试期7 d,正试期53 d。结果表明:与对照组相比,饲粮中添加6、12 mg/kg核黄素显著降低了獭兔肌肉的滴水损失(P<0.05),饲粮中添加3、6、12 mg/kg核黄素显著提高了獭兔皮肤中总毛囊密度(P<0.05),饲粮中添加3、6 mg/kg核黄素显著提高了獭兔皮肤中初级毛囊密度(P<0.05),饲粮中添加6、12 mg/kg核黄素显著提高了獭兔皮肤中次级毛囊密度(P<0.05),饲粮中添加3、6 mg/kg核黄素显著降低了獭兔皮肤中次级毛囊密度/初级毛囊密度(P<0.05)。饲粮中核黄素添加水平对獭兔的胸腺重、胸腺指数及血清免疫球蛋白G、免疫球蛋白A、白细胞介素-2含量影响显著(P<0.05),且均随着饲粮中核黄素添加水平的升高呈先增加后降低的趋势,均在6 mg/kg添加组中达到最大值,显著高于对照组(P<0.05)。由此可见,3~5月龄生长獭兔饲粮中核黄素适宜添加水平为6 mg/kg(实际测定饲粮中核黄素水平为8.35 mg/kg)。

  • 丁酸梭菌CBM01的碳、氮源优化及其对胃肠道耐受性的研究

    Subjects: Biology >> Zoology submitted time 2017-10-23 Cooperative journals: 《动物营养学报》

    Abstract:本试验旨在探究丁酸梭菌CBM01的最佳碳、氮源及其对胃肠道的耐受性。采用控制变量的方法,以梭菌增菌培养基为基础,对丁酸梭菌CBM01的碳、氮源进行优化,同时对其胃肠道耐受性进行研究。结果显示:1)丁酸梭菌CBM01的最佳碳源和最佳氮源分别为葡萄糖和蛋白胨;2)丁酸梭菌CBM01在人工胃液和人工肠液中作用3 h后,存活率分别为90.33%和92.09%;3)丁酸梭菌CBM01可耐受的最高胆盐浓度为0.40%。由此可见,丁酸梭菌CBM01对胃肠道环境具有良好的耐受性,是一株开发潜力巨大、应用前景广阔的益生菌。

  • 饲粮中胆碱添加水平对3~5月龄獭兔肝脏脂肪代谢的影响

    Subjects: Biology >> Zoology submitted time 2017-10-23 Cooperative journals: 《动物营养学报》

    Abstract:本试验旨在研究饲粮中胆碱添加水平对3~5月龄獭兔肝脏脂肪代谢的影响。选用200只体重相近的3月龄獭兔,随机分成5组(每组40个重复,每个重复1只),分别饲喂在基础饲粮基础上添加0(对照)、200、400、600和800 mg/kg的50%氯化胆碱(折算为胆碱的添加水平后分别为0、87、174、261和348 mg/kg)的试验饲粮,试验饲粮实测胆碱水平分别为800、900、1 000、1 100和1 200 mg/kg。预试期7 d,正试期53 d。结果表明:饲粮中胆碱添加水平显著影响肝脏中单不饱和脂肪酸和多不饱和脂肪酸的含量(P<0.05)。与对照组相比,饲粮中添加7、174、261和348 mg/kg的胆碱显著增加血清中类胰岛素样生长因子1(IGF-1)和瘦素(LEP)的含量(P<0.05),饲粮中添加174和261 mg/kg的胆碱显著增加血清中生长激素(GH)的含量(P<0.05),饲粮中添加261和348 mg/kg的胆碱显著增加血清中脂蛋白酯酶(LPL)的活性和极低密度脂蛋白(VLDL)的含量(P<0.05),饲粮中添加261 mg/kg的胆碱显著提高肝脏中肉碱棕榈酸转移酶1(CPT1)mRNA的表达水平(P<0.05)。综上所述,饲粮中添加261 mg/kg的胆碱(饲粮实测胆碱水平为1 000 mg/kg)改变了獭兔肝脏中脂肪酸组成,促进了肝脏中脂肪酸氧化关键基因CPT1的表达,同时加强了肝脏中甘油三酯(TG)的输出过程。

  • 饲粮钴添加水平对断奶至3月龄獭兔消化代谢的影响

    Subjects: Biology >> Zoology submitted time 2017-10-23 Cooperative journals: 《动物营养学报》

    Abstract:本试验旨在研究饲粮钴添加水平对断奶至3月龄獭兔饲粮营养物质表观消化率、氮代谢、胰腺消化酶活性、血清生化指标和钴代谢的影响。选择体重相近的断奶獭兔200只,随机分为5组,每组40个重复,每个重复1只试验兔。5组试验兔分别饲喂在基础饲粮中添加0(对照)、0.1、0.4、1.6、6.4 mg/kg钴(以硫酸钴的形式)的试验饲粮,经7 d预饲后进行为期53 d的饲养试验。结果显示:饲粮钴添加水平对饲粮中各营养物质的表观消化率均没有显著影响(P>0.05),但饲粮DM、CP和钴的表观消化率随饲粮钴添加水平的升高均有先升高后降低的趋势,DM和CP的表观消化率在钴添加水平为1.6 mg/kg时最高,钴的表观消化率在钴添加水平为0.4 mg/kg时最高。饲粮钴添加水平对粪氮(FN)、可消化氮(DN)、氮表观消化率(NAD)、氮生物学效价(NBV)均无显著影响(P>0.05),对食入氮(IN)、尿氮(UN)、氮沉积(RN)、氮利用率(NUR)有显著影响(P0.05)。饲粮钴添加水平对粪、尿、肌肉、脾脏和肾脏中钴含量有显著影响(P<0.05),且随着饲粮钴添加水平的升高,粪、尿、肌肉、脾脏和肾脏中钴含量均持续增加。综合本试验测定指标,断奶至3月龄獭兔饲粮钴适宜添加水平为0.4~1.6 mg/kg(饲粮中钴含量实测值为0.60~1.83 mg/kg)。

  • 饲粮中添加泛酸对生长獭兔肝脏脂肪代谢的影响

    Subjects: Biology >> Zoology submitted time 2017-10-23 Cooperative journals: 《动物营养学报》

    Abstract:本试验旨在研究饲粮中添加泛酸对家兔肝脏脂肪代谢的影响。试验选用体重相似的断奶獭兔160只,随机分为4组,每组40个重复,每个重复1只。对照组獭兔饲喂基础饲料,试验组獭兔分别饲喂在基础饲粮中添加10、20和40 mg/kg泛酸的饲粮。预试期7 d,正试期56 d。结果表明:与对照组相比,饲粮中添加40 mg/kg泛酸显著降低了生长獭兔肩胛、胃周和肾周脂肪沉积率(P0.05);随着饲粮中泛酸添加水平的升高,生长獭兔血浆中甘油三酯的含量先降低后趋于稳定,20、40 mg/kg添加组显著低于对照组(P<0.05);与对照组相比,饲粮中添加20~40 mg/kg泛酸显著升高了生长獭兔血浆中极低密度脂蛋白的含量(P<0.05)。与对照组相比,饲粮中添加40 mg/kg泛酸显著增加了肝脏中激素敏感脂酶(HSL)和骨骼肌中脂肪酸转运蛋白(FATP)基因的表达量(P<0.05);饲粮中添加20~40 mg/kg泛酸显著增加了肝脏中肉毒碱棕榈酰转移酶1(CPT1)基因的表达量(P<0.05);饲粮中添加10~40 mg/kg泛酸显著增加了肝脏中脂肪酸合成酶(FAS)基因和骨骼肌中CPT1基因的表达量(P<0.05)。综上所述,饲粮中添加泛酸影响生长獭兔肝脏内脂肪代谢,泛酸添加水平为40 mg/kg时可降低肝脏内脂肪的沉积,并能降低机体脂肪沉积率,增加骨骼肌对脂肪酸的摄取和利用。

  • 探测器VLBI信号仿真方法

    Subjects: Astronomy >> Astrophysical processes submitted time 2017-09-26 Cooperative journals: 《天文研究与技术》

    Abstract:为研究VLBI对探测器的数据处理方法并评估其处理能力,现有做法需基于测站VLBI终端接收的探测器信号进行。采用信号仿真方法可以根据设计轨道与信标特点利用计算机生成需要的探测器VLBI信号,相比试验观测具有独特优势。观测试验时,测站终端接收探测器下行射频信号,通过混频变换为中频信号,再进行数字化采集数据。仿真信号时,为减少计算规模,直接构造数字中频信号,二次采样后提取通道信号,获得数字终端的VLBI仿真信号。由于探测器相对VLBI测站运动,测站接收的探测器下行信号反映目标的视向速度变化。根据探测器信号时延模型,研究了探测器点频信号和有限带宽信号多普勒效应的模拟方法。通过仿真信号与VLBI终端接收信号的对比以及对VLBI相关处理结果的分析,验证了探测器VLBI信号仿真方法的可行性,为后续仿真技术在月球与火星探测器中的VLBI测定轨应用奠定了技术基础。