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Repeated inoculation with rumen fluid accelerates the rumen bacterial transition with no benefit on production performance in postpartum Holstein dairy cows
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作者 Fanlin Kong Feiran Wang +3 位作者 Yijia Zhang Shuo Wang Wei Wang Shengli Li 《Journal of Animal Science and Biotechnology》 SCIE CAS CSCD 2024年第2期795-811,共17页
Background The dairy cow’s postpartum period is characterized by dramatic physiological changes,therefore imposing severe challenges on the animal for maintaining health and milk output.The dynamics of the ruminal mi... Background The dairy cow’s postpartum period is characterized by dramatic physiological changes,therefore imposing severe challenges on the animal for maintaining health and milk output.The dynamics of the ruminal microbiota are also tremendous and may play a crucial role in lactation launch.We aim to investigate the potential benefits of early microbial intervention by fresh rumen microbiota transplantation(RMT)and sterile RMT in postpartum dairy cows.Twelve fistulated peak-lactation dairy cows were selected to be the donors for rumen fluid collection.Thirty postpartum cows were divided into 3 groups as the transplantation receptors respectively receiving 10 L fresh rumen fluid(FR),10 L sterile rumen fluid(SR),or 10 L saline(CON)during 3 d after calving.Results Production performance,plasma indices,plasma lipidome,ruminal microbiome,and liver transcriptome were recorded.After fresh and sterile RMT,we found that the molar proportion of propionic acid was increased on d 7 in the FR and SR groups and the bacterial composition was also significantly changed when compared with the CON group.A similarity analysis showed that the similarities between the CON group and FR or SR group on d 7 were 48.40%or 47.85%,whereas the similarities between microbiota on d 7 and 21 in the FR and SR groups were 68.34%or 66.85%.Dry matter intake and feed efficiency were not affected by treatments.Plasmaβ-hydroxybutyrate concentration in the FR group was decreased and significantly different lipids mainly included phosphatidylcholine and lysophosphatidylcholine containing polyunsaturated fatty acids.Hepatic transcriptomics analysis indicated acutephase response pathways were upregulated in the SR group.Conclusions Our study suggests that RMT can shorten the transition process of the ruminal microbiota of postpartum dairy cows with no benefit on dry matter intake or feed efficiency.Inoculation with rumen fluid may not be a useful approach to promote the recovery of postpartum dairy cows. 展开更多
关键词 Dairy cow LIPIDOMICS Liver Rumen microbiota transplantation transition period
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Floquet dynamical quantum phase transitions in transverse XY spin chains under periodic kickings
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作者 栾丽娜 张镁玉 王林成 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第9期144-152,共9页
Floquet dynamical quantum phase transitions(DQPTs),which are nonanalytic phenomena recuring periodically in time-periodic driven quantum many-body systems,have been widely studied in recent years.In this article,the F... Floquet dynamical quantum phase transitions(DQPTs),which are nonanalytic phenomena recuring periodically in time-periodic driven quantum many-body systems,have been widely studied in recent years.In this article,the Floquet DQPTs in transverse XY spin chains under the modulation ofδ-function periodic kickings are investigated.We analytically solve the system,and by considering the eigenstate as well as the ground state as the initial state of the Floquet dynamics,we study the corresponding multiple Floquet DQPTs emerged in the micromotion with different kicking moments.The rate function of return amplitude,the Pancharatnam geometric phase and the dynamical topological order parameter are calculated,which consistently verify the emergence of Floquet DQPTs in the system. 展开更多
关键词 Floquet dynamical quantum phase transitions periodic kick XY spin chains
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Transition Periods Between Sea Ice Concentration and Sea Surface Air Temperature in the Arctic Revealed by an Abnormal Running Correlation 被引量:2
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作者 JI Xupeng ZHAO Jinping 《Journal of Ocean University of China》 SCIE CAS CSCD 2019年第3期633-642,共10页
This study used the synthetic running correlation coefficient calculation method to calculate the running correlation coefficients between the daily sea ice concentration(SIC) and sea surface air temperature(SSAT) in ... This study used the synthetic running correlation coefficient calculation method to calculate the running correlation coefficients between the daily sea ice concentration(SIC) and sea surface air temperature(SSAT) in the Beaufort-Chukchi-East Siberian-Laptev Sea(BCEL Sea), Kara Sea and southern Chukchi Sea, with an aim to understand and measure the seasonally occurring changes in the Arctic climate system. The similarities and differences among these three regions were also discussed. There are periods in spring and autumn when the changes in SIC and SSAT are not synchronized, which is a result of the seasonally occurring variation in the climate system. These periods are referred to as transition periods. Spring transition periods can be found in all three regions, and the start and end dates of these periods have advancing trends. The multiyear average duration of the spring transition periods in the BCEL Sea, Kara Sea and southern Chukchi Sea is 74 days, 57 days and 34 days, respectively. In autumn, transition periods exist in only the southern Chukchi Sea, with a multiyear average duration of only 16 days. Moreover, in the Kara Sea, positive correlation events can be found in some years, which are caused by weather time scale processes. 展开更多
关键词 ARCTIC SEA ice CONCENTRATION SEA surface air temperature synthetic running CORRELATION coefficient transition period
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Tuning Second Chern Number in a Four-Dimensional Topological Insulator by High-Frequency Time-Periodic Driving
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作者 刘峥嵘 陈锐 周斌 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第4期77-89,共13页
Floquet engineering has attracted considerable attention as a promising approach for tuning topological phase transitions.We investigate the effects of high-frequency time-periodic driving in a four-dimensional(4D)top... Floquet engineering has attracted considerable attention as a promising approach for tuning topological phase transitions.We investigate the effects of high-frequency time-periodic driving in a four-dimensional(4D)topological insulator,focusing on topological phase transitions at the off-resonant quasienergy gap.The 4D topological insulator hosts gapless three-dimensional boundary states,characterized by the second Chern number C_(2).We demonstrate that the second Chern number of 4D topological insulators can be modulated by tuning the amplitude of time-periodic driving.This includes transitions from a topological phase with C_(2)=±3 to another topological phase with C_(2)=±1,or to a topological phase with an even second Chern number C_(2)=±2,which is absent in the 4D static system.Finally,the approximation theory in the high-frequency limit further confirms the numerical conclusions. 展开更多
关键词 TOPOLOGICAL transitionS periodIC
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Lost Women in Social Transitional Period——A Comparative Study of the Tragic Fate of Sister Carrie and Guo Haizao
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作者 陈晶晶 《海外英语》 2014年第14期172-173,176,共3页
Sister Carrie and Dwelling depict two heroines who share similarities in many aspects. They all live in the social transitional period and suffer a lot. This paper will make a comparison about the two ladies' trag... Sister Carrie and Dwelling depict two heroines who share similarities in many aspects. They all live in the social transitional period and suffer a lot. This paper will make a comparison about the two ladies' tragic fates and aims to investigate the impact on females brought about by the social transition. 展开更多
关键词 SISTER CARRIE DWELLING SOCIAL transitional period
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Empirical Research on the Factors of Chinese City Growth in the Transitional Period
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作者 LI Yingjie YANG Yongchun 《Asian Agricultural Research》 2010年第7期1-5,共5页
Based on the definition of the concept of city growth, the paper mainly discussed the factors which impact the growth of Chinese cities in the transitional period by selecting the proportion of city construction land ... Based on the definition of the concept of city growth, the paper mainly discussed the factors which impact the growth of Chinese cities in the transitional period by selecting the proportion of city construction land area to the area of the city X1(%), green coverage ratio of the built up area X2(%), the ratio of personnel involved in the secondary industry X3(%), the GDP per capita X4(×104)and other 43 indicators, by relying on the relevant data from China Urban Statistical Yearbook(2008), applying SPSS statistical software and by applying the Factor Analysis and Regression Analysis. The results show that the factors which affect the city growth have four major groups, namely economic and institutional factors, location factors, environmental factors and social cultural services and functions. Among the factors which affect Chinese city growth, the general budgetary expenditures and the general budgetary revenues of local public finance are the most important factors. The general budgetary expenditures of local finance, the general budgetary revenues, the lands of urban construction and other 12 factors obtained by gradually excluding method can be used to present the coefficient of city growth. 展开更多
关键词 transitional period City growth Chinese cities FACTORS China
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Topological phase transition in cavity optomechanical system with periodical modulation
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作者 Zhi-Xu Zhang Lu Qi +2 位作者 Wen-Xue Cui Shou Zhang Hong-Fu Wang 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第7期104-111,共8页
We investigate the topological phase transition and the enhanced topological effect in a cavity optomechanical system with periodical modulation.By calculating the steady-state equations of the system,the steady-state... We investigate the topological phase transition and the enhanced topological effect in a cavity optomechanical system with periodical modulation.By calculating the steady-state equations of the system,the steady-state conditions of cavity fields and the restricted conditions of effective optomechanical couplings are demonstrated.It is found that the cavity optomechanical system can be modulated to different topological Su–Schrieffer–Heeger(SSH)phases via designing the optomechanical couplings legitimately.Meanwhile,combining the effective optomechanical couplings and the probability distributions of gap states,we reveal the topological phase transition between trivial SSH phase and nontrivial SSH phase via adjusting the decay rates of cavity fields.Moreover,we find that the enhanced topological effect of gap states can be achieved by enlarging the size of system and adjusting the decay rates of cavity fields. 展开更多
关键词 topological phase transition periodical modulation enhanced topological effect
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Chinese Thoughts on domain on the value of standard during the period of social transition
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作者 Ping-JingQiu 《International Journal of Technology Management》 2014年第5期19-21,共3页
values occupy an important position in the lives of the people, almost all the joy, happiness, sadness, unfortunately are related with the values. It pervades all aspects of social life, reflects the contradictions an... values occupy an important position in the lives of the people, almost all the joy, happiness, sadness, unfortunately are related with the values. It pervades all aspects of social life, reflects the contradictions and conflicts of the various aspects. While Chinese society is undergoing a transformation of the special period, Social value orientation of instability makes further thought and exploration,in order to get a judgement conform to social development and human interests of social value standard. 展开更多
关键词 transition period VALUE DOMAIN
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A model of local labor market regulation of China in the transition period
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作者 VeQi 《Ecological Economy》 2009年第1期50-61,共12页
With the establishment of labor market of China, market is playing a more and mare important role in allocation of human resources. However, with the transition of economy in China and industrial upgrading in recent y... With the establishment of labor market of China, market is playing a more and mare important role in allocation of human resources. However, with the transition of economy in China and industrial upgrading in recent years, many labor problems have occurred which do harm to the sustainable development of local economy. The paper researches on the labor market issues of China from the perspective of local labor market regulation. Firstly, it reviews the theories of local labor market regulation. And then the main components of local labor market regulation of China are identified and the evaluation index system is established. The results of analysis of the calculated output show that (1) the local labor market regulation of China has an obvious character of gradient distribution geographically and decreases gradually from east to west; (2) of all the regulations, the regulation of the development of human capital has the most significant impact on local economy currently which is followed by the regulation of labor relation and the regulation of market participation. As to the regulation of social security, it has no Significant impact on the development of local economy. 展开更多
关键词 Local labor market REGULATION transition period
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Effects of far-off and close-up transition cow feeding on uterine health,postpartum anestrous interval,and reproductive outcomes in pasture-based dairy cows 被引量:3
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作者 S.Meier J.K.Kay +6 位作者 B.Kuhn-Sherlock A.Heiser M.D.Mitchell M.A.Crookenden M.Vailati Riboni J.J.Loor J.R.Roche 《Journal of Animal Science and Biotechnology》 CAS CSCD 2020年第2期493-503,共11页
Background:In seasonal,pasture-based,dairy production systems,cows must recover from calving and become pregnant within two to 3 months.To achieve this,the uterus must involute and ovulation must occur and continue at... Background:In seasonal,pasture-based,dairy production systems,cows must recover from calving and become pregnant within two to 3 months.To achieve this,the uterus must involute and ovulation must occur and continue at regular intervals.As these processes are affected by the cows’nutritional or metabolic status post-calving,the objective of this study was to evaluate the effect of cow feeding strategies on uterine health,the length of postpartum anestrous interval,and reproductive outcomes.The treatments consisted of two feeding strategies during late-lactation and early dry period(far-off period;starting 4-month pre-calving)and three close-up dry period feeding regimes(1-month pre-calving)in a 2×3 factorial arrangement.We randomly assigned 150 cows to one of two far-off treatments.During late lactation,the herds(n=75 cows per herd)were either control-fed(Controlfed)or over-fed(Overfed)to achieve a low or high body condition score(4-month pre-calving;BCS;~4.25 and^4.75;10-point scale)at cessation of lactation.Within each of these treatments,three feeding levels were applied during the close-up period(1-month pre-calving):~65%(Feed65),~90%(Feed90),or^120%(Feed120)of metabolizable energy(ME)intakes relative to pre-calving requirements.Results:Uterine health improved(i.e.polymorphonucleated(PMN)cells declined)with increased feeding during the close-up period for cows in the Overfed group.The reverse was evident for the Controlfed group with the greatest PMN at the highest intakes during the close-up period.The postpartum anoestrous interval(PPAI)was shorter in cows from the Overfed group when moderately fed(Feed90)during the close-up period;in comparison,the PPAI was shorter in the Controlfed group,when those cows were overfed in the close-up period(Feed120).The cows in the Overfed treatment had greater conception and pregnancy rates if cows had moderate dry matter intakes(Feed90)during the close-up period;these reproductive variables were less under excessive feed intakes(Feed120);yet,close-up dry matter intake had little effect on conception and pregnancy rates for the Controlfed group.Conclusions:The far-off feeding strategies increased early reproductive outcomes at 3 weeks of mating.Additionally,the interaction between far-off and close-up feeding strategies resulted in high six-week pregnancy rate with a slight restriction during the close-up period but only in the far-off Overfed group.Thus,our hypothesis is supported under these conditions. 展开更多
关键词 Close-up Dairy cows Far-off Reproduction transition period
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Precessing Ball Solitons as Self-Organizing Systems during a Phase Transition in a Ferromagnet
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作者 V. V. Nietz 《Applied Mathematics》 2013年第10期78-83,共6页
Precessing ball solitons (PBS) in a ferromagnet during the first order phase transition is induced by a magnetic field directed along the axis of anisotropy, while the action of the periodic field perpendicular to the... Precessing ball solitons (PBS) in a ferromagnet during the first order phase transition is induced by a magnetic field directed along the axis of anisotropy, while the action of the periodic field perpendicular to the main magnetic field has been analyzed. Under these conditions, the characteristics of arising equilibrium PBS are uniquely determined by the frequency of the periodic field, but the solitons with other frequencies are impossible. For such structure, the entropy increase connected with dissipation is compensated by the decrease of the entropy due to the external periodic field. It is shown that the equilibrium PBS are essentially the “self-organizing systems” that can arise spotaneously in a metastable state of ferromagnet. 展开更多
关键词 FERROMAGNET MAGNETIC FIELD periodic MAGNETIC FIELD First-Order Phase transition Precessing BALL Soliton DISSIPATIVE MAGNETIC Structures SELF-ORGANIZING Systems
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Last train timetable optimization for metro network to maximize the passenger accessibility over the end-of-service period
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作者 Fang Wen Yun Bai +2 位作者 Xin Zhang Yao Chen Ninghai Li 《Railway Sciences》 2023年第2期273-288,共16页
Purpose-This study aims to improve the passenger accessibility of passenger demands in the end-ofoperation period.Design/methodology/approach-A mixed integer nonlinear programming model for last train timetable optim... Purpose-This study aims to improve the passenger accessibility of passenger demands in the end-ofoperation period.Design/methodology/approach-A mixed integer nonlinear programming model for last train timetable optimization of the metro was proposed considering the constraints such as the maximum headway,the minimum headway and the latest end-of-operation time.The objective of the model is to maximize the number of reachable passengers in the end-of-operation period.A solution method based on a preset train service is proposed,which significantly reduces the variables of deciding train services in the original model and reformulates it into a mixed integer linear programming model.Findings-The results of the case study of Wuhan Metro show that the solution method can obtain highquality solutions in a shorter time;and the shorter the time interval of passenger flow data,the more obvious the advantage of solution speed;after optimization,the number of passengers reaching the destination among the passengers who need to take the last train during the end-of-operation period can be increased by 10%.Originality/value-Existing research results only consider the passengers who take the last train.Compared with previous research,considering the overall passenger demand during the end-of-operation period can make more passengers arrive at their destination.Appropriately delaying the end-of-operation time can increase the proportion of passengers who can reach the destination in the metro network,but due to the decrease in passenger demand,postponing the end-of-operation time has a bottleneck in increasing the proportion of passengers who can reach the destination. 展开更多
关键词 Urban rail transit Last train of metro Timetable optimization End-of-operation period Passenger demand OD reachability
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新入职护士过渡期不同阶段职场适应的真实体验 被引量:1
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作者 韩娟 张蜜 +5 位作者 高雅 李洁琼 马佳佳 汤逸蘋 游宁 刘婷 《护士进修杂志》 2024年第20期2145-2150,共6页
目的探索新入职护士在过渡期不同阶段职场适应的工作体验,了解其在护理岗位适应过程中面临的各种压力、情感体验及行为形成,进一步探索并优化新入职护士培训方案的相关内容。方法本研究采用现象学研究方法,于2023年3-6月在西安交通大学... 目的探索新入职护士在过渡期不同阶段职场适应的工作体验,了解其在护理岗位适应过程中面临的各种压力、情感体验及行为形成,进一步探索并优化新入职护士培训方案的相关内容。方法本研究采用现象学研究方法,于2023年3-6月在西安交通大学第一附属医院对20名新入职护士进行半结构式深入访谈,并使用Colaizzi 7步分析法对访谈内容进行整理分析。结果提炼得出4个主题和9个亚主题,分别为职业认知(入职1个月)(工作环境不熟悉、角色转化困难、职业认同困扰)、学习适应(2~3个月)(岗位能力不足、自我否定、)、融入环境(4~6个月)(缺乏专科知识、缺乏组织归属感、)、职业胜任(7~12个月)(预警和应对突发事件能力不足、岗位不确定性所致的焦虑)。结论新入职护士过渡期的规范化培训对其职业适应及职业发展至关重要,护理管理者可通过了解新护士过渡期不同阶段职场适应的工作体验,优化培训方案,增加新护士职业认同、心理健康的相关培训,帮助新护士尽早适应临床工作。 展开更多
关键词 新入职护士 过渡期 职场适应 真实体验 质性研究
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西太平洋中中新世转型的天文轨道周期特征
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作者 王海峰 邓希光 +1 位作者 易亮 何高文 《地质论评》 CAS CSCD 北大核心 2024年第S01期19-20,共2页
中中新世气候转型是一次深刻的全球降温事件,地球各圈层,包括大气圈、水圈、生物圈、岩石圈、冷圈均发生了显著的变化,对理解新生代全球气候突变具有重要的借鉴意义。西太平洋GC18沉积柱样完整记录了中中新世15~11 Ma的沉积记录。本研... 中中新世气候转型是一次深刻的全球降温事件,地球各圈层,包括大气圈、水圈、生物圈、岩石圈、冷圈均发生了显著的变化,对理解新生代全球气候突变具有重要的借鉴意义。西太平洋GC18沉积柱样完整记录了中中新世15~11 Ma的沉积记录。本研究基于该柱样精确的年代学框架,开展了岩芯地球化学扫描. 展开更多
关键词 西太平洋 中中新世转型 天文轨道周期
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塔里木盆地F_(Ⅰ)17走滑断裂北段奥陶纪差异变形机制
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作者 蔡振忠 李兵 +4 位作者 罗枭 李会元 李梦勤 李正阳 王青红 《新疆石油地质》 CAS CSCD 北大核心 2024年第4期401-408,共8页
为明确走滑断裂对碳酸盐岩油气成藏的作用,基于三维地震资料,分析F_(Ⅰ)17走滑断裂北段的发育特征与构造变形过程,结合地质建模,开展走滑断裂形成及演化的砂箱物理模拟。研究区内的F_(Ⅰ)17走滑断裂可分为南、北2段,南段为近北东—南西... 为明确走滑断裂对碳酸盐岩油气成藏的作用,基于三维地震资料,分析F_(Ⅰ)17走滑断裂北段的发育特征与构造变形过程,结合地质建模,开展走滑断裂形成及演化的砂箱物理模拟。研究区内的F_(Ⅰ)17走滑断裂可分为南、北2段,南段为近北东—南西走向,主要发育雁列式断裂,奥陶纪一间房组整体以隆升为主,垂向上的变形幅度较大;北段为近北北东—南南西走向,主要发育线性走滑断裂,在奥陶纪一间房组变形微弱,局部地区可见地层微幅度下掉。砂箱物理模拟实验结果表明:线性走滑断裂的主位移带上会形成一系列隆起带,而走向偏转的走滑断裂在南段形成一系列隆起带,在北段则表现为地层下掉;在同一应力条件下,走滑断裂初始走向的差异会导致断裂受力发生变化,进而影响其演化过程。F_(Ⅰ)17走滑断裂南段的压隆段应力更加集中,局部裂缝和溶洞更发育,油气更为富集,油气勘探效果优于北段。 展开更多
关键词 塔里木盆地 阿满过渡带 奥陶纪 走滑断裂 差异变形机制 物理模拟
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近百年中国历史创造中的传统与创新
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作者 郭湛 《海南大学学报(人文社会科学版)》 CSSCI 2024年第6期1-8,F0002,共9页
近百年来中国之所以能够成就民族复兴、国家富强的历史伟业,根本原因就在于中国共产党和中国人民持续推进中华文明优秀传统的继承与创新。在民族振兴和国家富强进程中不断彰显中国共产党所长期坚持的主体性与创造性,不仅坚持以中国化时... 近百年来中国之所以能够成就民族复兴、国家富强的历史伟业,根本原因就在于中国共产党和中国人民持续推进中华文明优秀传统的继承与创新。在民族振兴和国家富强进程中不断彰显中国共产党所长期坚持的主体性与创造性,不仅坚持以中国化时代化的马克思主义指导中国革命、建设和改革,而且在创造、创新的基础上推进观念、制度等各方面的创优发展,从而形成了具有世界新型文明属性的中国式现代化道路。而在现阶段出现多制共存的“过渡时期”文明的新常态,决定了新型社会主义文明将与其他文明在竞争与合作中形成人类命运共同体,这将是世界历史“过渡时期”的人类命运共同体文明,这也是中华文明对世界和人类未来发展的新贡献。 展开更多
关键词 中国历史 过渡时期 社会主义文明
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NSICU过渡期患者家属需求现况调查及影响因素分析
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作者 方建冰 黄德斌 +2 位作者 黎秀婵 赖海燕 吕寿强 《现代医药卫生》 2024年第4期630-633,638,共5页
目的调查神经外科重症监护室(NSICU)过渡期患者家属需求现状,并分析其影响因素,为开展下一步的干预措施提供理论依据。方法采用便利抽样法选取2022年11月至2023年4月该院收治的NSICU过渡期患者家属115例作为研究对象。采取一般资料调查... 目的调查神经外科重症监护室(NSICU)过渡期患者家属需求现状,并分析其影响因素,为开展下一步的干预措施提供理论依据。方法采用便利抽样法选取2022年11月至2023年4月该院收治的NSICU过渡期患者家属115例作为研究对象。采取一般资料调查问卷、ICU过渡期患者家属需求量表、ICU转出患者家属迁移应激量表分别对患者家属进行调查。结果115例患者家属平均ICU过渡期患者家属需求量表得分为(100.17±8.38)分,与ICU转出患者家属迁移应激量表总分呈正相关,差异有统计学意义(P<0.05)。有无照顾经验、患者入住NSICU方式、迁移应激水平为NSICU过渡期患者家属需求的影响因素,差异均有统计学意义(P<0.05)。结论NSICU过渡期患者家属需求水平较高,医护人员应对患者家属有无照顾经验、患者入住NSICU方式、迁移应激等因素实施个体化干预,以满足患者家属的需求。 展开更多
关键词 神经外科重症监护室 过渡期 患者家属需求 调查和问卷 影响因素分析
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基于MS(2)-AR-TVTP模型的I_(BD)波动周期非对称性和持续性分析
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作者 陈丽芬 谢新连 林嘉俊 《中国航海》 CSCD 北大核心 2024年第2期65-71,共7页
国际干散货运输市场源于国际贸易的衍生需求,受世界经济的影响,是一个典型的周期性市场。选取1999年11月~2021年12月的波罗的海干散货运价指数(I_(BD))月度数据,在检验序列平稳性的基础上,确定最优滞后长度,构建两区制的时变转换概率马... 国际干散货运输市场源于国际贸易的衍生需求,受世界经济的影响,是一个典型的周期性市场。选取1999年11月~2021年12月的波罗的海干散货运价指数(I_(BD))月度数据,在检验序列平稳性的基础上,确定最优滞后长度,构建两区制的时变转换概率马尔科夫转换自回归模型,分析I_(BD)波动周期的持续时间、转换拐点和非对称性等主要特征。研究结果表明:模型能有效拟合I_(BD)波动周期的主要特征,周期平均持续时间为33.7个月,自2008年9月之后呈缩短态势,上升期和下降期交互更频繁;I_(BD)波动周期具有非对称性,周期内上升期持续时间比下降期长,I_(BD)维持上升期更具有稳定性。周期性特征结果可为干散货航运业造船投资和市场经营提供决策依据。 展开更多
关键词 MS(2)-AR-TVTP模型 I_(BD)波动周期 转换拐点 持续时间
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“雨露均沾”抑或“强强联合”:衔接过渡期驻村帮扶资源配置逻辑及其实践后果
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作者 兰剑 程博 《西南大学学报(社会科学版)》 CSSCI 北大核心 2024年第5期90-102,共13页
驻村帮扶是衔接过渡期巩固好脱贫成果、接续推进乡村振兴的重要制度支撑。通过对西部地区两县驻村帮扶工作的调查研究发现,与脱贫攻坚时期更加注重全面帮扶的“雨露均沾”不同,衔接过渡期驻村帮扶资源配置更加注重“强强联合”,在乡村... 驻村帮扶是衔接过渡期巩固好脱贫成果、接续推进乡村振兴的重要制度支撑。通过对西部地区两县驻村帮扶工作的调查研究发现,与脱贫攻坚时期更加注重全面帮扶的“雨露均沾”不同,衔接过渡期驻村帮扶资源配置更加注重“强强联合”,在乡村振兴示范点创建的工作机制与目标指引下,一些重点乡村建设项目和资源被少数优势村庄捕获,驻村帮扶强势主客体间存在着理性的“共同谋划”,而部分弱势村庄则深陷于自身基础薄弱和外来资源稀缺的两难境地。驻村帮扶主客体的“强强联合”在一定程度上导致了驻村帮扶主体的行为偏差、村际水平上新的不公平、制度效能低下与低水平管理困境等后果。因此,应加快构建驻村帮扶资源的精准匹配与县域资源统筹共享机制,拓展资源供给渠道并优化驻派结构,以提升帮扶资源配置的公平性和整体帮扶效能。 展开更多
关键词 乡村振兴 衔接过渡期 驻村帮扶 驻村干部 资源配置 底线公平 精英捕获
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围产期母体营养调控对犊牦牛生长发育、血清生化及免疫功能的影响 被引量:1
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作者 尚恺圆 江明锋 +9 位作者 官久强 安添午 赵洪文 柏琴 吴伟生 李华德 谢荣清 沙泉 罗晓林 张翔飞 《畜牧兽医学报》 CAS CSCD 北大核心 2024年第4期1638-1648,共11页
本研究基于高寒牧区牦牛产业母犊培育现状,旨在探究围产期母体营养均衡供给与早期断奶的营养调控方式对犊牛生长发育、血清生化及免疫功能的影响,为牦牛高效养殖提供科学基础。研究选取18头健康、体重相近、胎次为2~4次、预产期相近的... 本研究基于高寒牧区牦牛产业母犊培育现状,旨在探究围产期母体营养均衡供给与早期断奶的营养调控方式对犊牛生长发育、血清生化及免疫功能的影响,为牦牛高效养殖提供科学基础。研究选取18头健康、体重相近、胎次为2~4次、预产期相近的妊娠后期麦洼牦牛,随机分为放牧对照组(GF)、营养供给组(SF)、早期断奶组(SW)3个组(n=6),GF组牦牛产前及产后阶段均于天然牧场自然放牧,SF组牦牛在产前30 d至产后90 d按妊娠后期、泌乳早期营养需要以“精料+青干草+放牧”方式给予营养均衡供给,SW组牦牛在营养均衡供给基础上,于产后60 d对犊牛进行早期断奶处理。对GF、SF、SW组牦牛所产犊牛初生重、90 d体重及体尺指标进行测定,并采集犊牛90日龄血清样本,分析不同母体营养调控方式下犊牦牛血清生化、生长相关激素分泌及免疫功能差异。结果表明,SF和SW组犊牛的初生重显著高于GF组(P<0.05);90日龄时,SF和SW组犊牦牛的体重、体高以及胸围均显著高于GF组(P<0.05),SW与SF组之间犊牛体重、体尺无显著差异(P>0.05)。与GF组相比,SF和SW组犊牛血清葡萄糖(GLU)、球蛋白(GLB)、胆固醇(CHO)浓度显著上升(P<0.05);SF组TP水平显著高于GF组(P<0.05)。生长相关激素方面,SF和SW组胰岛素样生长因子I(IGF-Ⅰ)水平显著高于GF组(P<0.05);SW组生长激素(GH)浓度显著高于GF组(P<0.05)。SF、GF组犊牦牛血清分泌型免疫球蛋白A(sIgA)浓度显著高于SW组(P<0.05)。相较于GF组,SF、SW组血清免疫球蛋白A(IgA)水平显著升高(P<0.05),SF组血清免疫球蛋白G(IgG)浓度显著高于GF组(P<0.05)。综上所述,营养均衡供给为妊娠后期和泌乳前期牦牛母体提供了充足的养分,通过增加犊牦牛养分摄入,提升了犊牛初生重、血清糖、氮营养代谢物水平,增加了生长相关激素及免疫球蛋白水平,从而促进了犊牦牛生长发育;早期断奶搭配营养均衡供给方式对犊牦牛生长发育、免疫功能无显著负面影响,并进一步促进生长激素分泌。 展开更多
关键词 围产期 营养调控 早期断奶 犊牦牛 生长发育
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