Seasonal and Interannual Variations of Carbon Exchange over a Rice–Wheat Rotation System on the North China Plain

Rice-wheat （R-W） rotation systems are ubiquitous in South and East Asia, and play an important role in modulating the carbon cycle and climate. Long-term, continuous flux measurements help in better understanding the seasonal and interannual variation of the carbon budget over R-W rotation systems. In this study, measurements of CO2 fluxes and meteorological variables over an R-W rotation system on the North China Plain from 2007 to 2010 were analyzed. To analyze the abiotic factors regulating Net Ecosystem Exchange （NEE）, NEE was partitioned into gross primary production （GPP） and ecosystem respiration. Nighttime NEE or ecosystem respiration was controlled primarily by soil temperature, while daytime NEE was mainly determined by photosythetically active radiation （PAR）. The responses of nighttime NEE to soil temperature and daytime NEE to light were closely associated with crop development and photosynthetic activity, respectively. Moreover, the interannual variation in GPP and NEE mainly depended on precipitation and PAR. Overall, NEE was negative on the annual scale and the rotation system behaved as a carbon sink of 982 g C m 2 per year over the three years. The winter wheat field took up more CO2 than the rice paddy during the longer growing season, while the daily NEE for wheat and rice were -2.35 and -3.96 g C m-2, respectively. After the grain harvest was subtracted from the NEE, the winter wheat field became a moderately strong carbon sink of 251-334 g C m-2 per season, whereas the rice paddy switched to a weak carbon sink of 107-132 per season.

A Brief Study on pH, Exchangeable Ca²⁺and Mg²⁺in Farmlands under Tobacco-Rice Rotation in Xuancheng City of South Anhui

pH, exchangeable Ca2+ and Mg2+ of soil can influence the yield and quality of flue-cured tobacco. Xuancheng city is the dominant tobacco-planting region in Anhui province since 2008. A general soil survey was conducted in Xuancheng city to understand the current situations of pH, exchangeable Ca2+ and Mg2+ of farmlands under tobacco-rice rotation and to decide whether continuous applying dolomite powders to abate soil acidification. In total 124 topsoil samples (0-20 cm) were collected from the typical farmlands and soil pH, exchangeable Ca2+ and Mg2+ were measured. The results showed that soil pH and Ca2+ and Mg2+ in Xuancheng city were generally in the suitable grades, pH ranged from 4.56 to 8.42 with an average of 5.87, exchangeable Ca2+ ranged from 1.01 cmol(1/2Ca2+) kg-1 to 100.55 cmol(1/2Ca2+) kg-1 with an average of 11.07 cmol(1/2Ca2+) kg-1, and exchangeable Mg2+ ranged from 0.14 cmol(1/2Mg2+) kg-1 to 2.86 cmol(1/2Mg2+) kg-1 with an average of 0.81 cmol(1/2Mg2+) kg-1, all spanned from the low grades to the high grades. To the whole Xuancheng city, 37.10%, 62.10% and 72.58% of the surveyed farmlands were in the low grades of pH, exchangeable Ca2+ and Mg2+, respectively, while 52.42%, 25.00% and 20.97% of the farmlands were in the suitable grades, respectively. pH had an extremely significantly positive Napierian logarithm correlation with exchangeable Ca2+ and an extremely significantly positive power correlation with exchangeable Mg2+. In total about 338.2 kg·hm-2 of Ca2+ and 202.4 kg·hm-2 of Mg2+ are annually input into the farmlands, while about 110.4 kg·hm-2 of Ca2+ and 7.4 kg·hm-2 of Mg2+ are annually moved out from the farmlands, exchangeable Ca2+ and Mg2+ were annually increased by 225.2 kg·hm-2 and 187.6 kg·hm-2 in the farmlands, respectively. It is necessary to monitor the farmlands dynamically in order to decide whether continuous applying dolomite powders which should be dependent upon the specific conditions of individual farmlands.

The rotational anisotropies in the ferromagnetism/antiferromagnetism 1/ antiferromagnetism 2 exchange bias structures

The rotational anisotropies in the exchange bias structures of ferromagnetism/antiferromagnetism 1/antiferro- magnetism 2 are studied in this paper. Based on the model, in which the antiferromagnetism is treated with an Ising mean field theory and the rotational anisotropy is assumed to be related to the field created by the moment induced on the antiferromagnetic layer next to the ferromagnetic layer, we can explain why in experiments for ferromag- netism （FM）/antiferromagntism 1 （AFM1）/antiferromagnetism 2 （AFM2） systems the thickness-dependent rotational anisotropy value is non-monotonic, i.e. it reaches a minimum for this system at a specific thickness of the first anti- ferromagnetic layer and exhibits oscillatory behaviour. In addition, we find that the temperature-dependent rotational anisotropy value is in good agreement with the experimental result.

Profile Measurement of Ion Temperature and Toroidal Rotation Velocity with Charge Exchange Recombination Spectroscopy Diagnostics in the HL-2A Tokamak

This paper deals with the profile measurement of impurity ion temperature and toroidal rotation velocity that can be achieved by using the charge exchange recombination spectrum （CXRS） diagnostics tool built on the HL-2A toknmak. By using CXRS, an accurate impurity ion temperature and toroidal plasma rotation velocity profile can be achieved under the condition of neutrM beam injection （NBI） heating. Considering the edge effect of the line of CVI 529.06 nm （n= 8-7）, which contains three lines （active exciting spectral line （ACX）, passivity exciting spectral line （PCX） and electron exciting spectral line （ICE））, and using three Gaussian fitted curves, we obtain the following experimental results： the core ion temperature of HL-2A device is nearly thousands of eV, and the plasma rotation velocity reaches about 104 m· s^-1. At the end of paper, some explanations are presented for the relationship between the curves and the inner physical mechanism.

An EPR Study on Intramolecular Spin Exchange and Rotational Mobility of Nitroxides Linked by a Long-chain

The effects of pressure and solvent on the intramolecular spin exchange of biradicals having two nitroxide fragments linked by a long flexible chain were studied by means of highpressure EPR technique.It was found that the intramolecular exchange interaction between nitroxides of biradical took place through the direct contact between them.By analyzing the observed EPR spectra,we have estimated the ratio(in/out)value of the average lifetime of the radical fragments inside a cage(in)to that outside the cage(out).The in/out values decreased with decreasing temperature and increasing pressure.The results suggest that the nearly cyclic conformation in a cage is favorable in solution.Further,the rotational correlation time of individual nitroxide was estimated from the anisotropic EPR signal,and the information on the segmental motion of the nitroxide group in biradical was obtained.

The Hysteretic Behavior of Angular Dependence of Exchange Bias in NiFe/granular-FeMn-MgO Bilayers

We investigate the hysteretic behavior of the angular dependence of exchange bias for a series of polycrystalline NiFe/(FeMn)_(1-x)(MgO)_(x) bilayers with varying x.For x=0.025,the antiferromagnetic layer is of the largest degree of the fcc(111)preferred texture.At the same x,both the exchange field and blocking temperature acquire maximal values.In particular,the hysteretic behavior of the angular dependence between clockwise and counter-clockwise rotations shows minimal angular shift.These results can be explained in terms of the thermal activation model.

Effects of Coordinate Rotation on Turbulent Flux Measurements during Wintertime Haze Pollution in Beijing, China

Eddy-covariance observations from the Beijing 325-m meteorological tower are used to evaluate the effects of coordinate rotation on the turbulent exchange of momentum and scalars during wintertime haze pollution(January-February 2013). Two techniques are used in the present evaluation; namely, the natural wind coordinate(NWC) and the planar fit coordinate(PFC), with the latter being applied by means of two methods for linear regression(i.e., overall and sector-wise). The different techniques show a general agreement in both turbulent fluxes and transport efficiencies, especially evident at the lower, 140-m level above the ground(compared to the higher, 280-m level), perhaps implying that the selection of a technique for coordinate rotation(NWC or PFC) is less of a concern for a sufficiently low level, despite the complexities of urban terrain. Additionally, sector-wise regression is a recommended approach for practical application of the PFC in a complex urban environment subjected to particulate pollution, because this method is found to produce a better correlation between the mean vertical velocity at the 140- and 280-m heights.

政策网络视角下县域教师交流政策的执行困境与破解路径——基于辽宁省T县的案例研究

教师交流是促进义务教育均衡发展的关键举措。本研究立足于辽宁省T县义务教育教师交流政策执行调研实况,利用政策网络理论分析框架,分析教师交流政策主体间的互动关系对政策执行成效的影响机制。研究发现,县域教师交流政策网络主体主要包括政策社群网络、府际网络、校际网络和议题网络,各网络主体之间的互动关系对县域教师交流政策执行成效具有显著影响作用。县域教师交流政策执行面临着政策社群网络内部的部门协同不畅、政策社群网络与府际网络间的利益取向冲突、校际网络内部的资源流动不畅、议题网络的参与程度不高等四大困境。基于此,破解县域教师交流政策执行中所面临的困境应畅通政策社群网络内部的跨部门合作通道,稳固跨部门合作关系;按照纵向职责同构原则,明确政策社群网络和府际网络的职责分工;调整校际网络内部的互动模式,疏通县乡学校交流渠道;畅通议题网络参与渠道,激发议题网络规模效应;调整校际网络内部的互动模式,疏通县乡学校交流渠道;畅通议题网络参与渠道,激发议题网络的规模效应。

中国城乡教师交流轮岗政策的历史变迁、演进逻辑与未来走向

乡村教师作为教育教学活动的主体,直接影响着乡村教育教学质量,更关系到乡村振兴的人才根基。中国城乡教师交流轮岗政策大致经历了初步探索、规范建制、制度深化三个阶段。在此过程中,城乡教师交流轮岗政策的动力机制、价值取向、过程保障和话语体系有着自身的演进逻辑。该政策的未来走向将以“省域统筹、县管校聘、弱势补偿”为动力机制、以确立城乡师资优质均衡发展为价值取向、以健全城乡交流轮岗教师在地化发展为过程保障、以契合多元主体的利益诉求为政策话语,从而构成未来城乡教师交流轮岗政策的新框架。

义务教育交流轮岗教师专业发展的理念、逻辑及路径

义务教育交流轮岗教师专业发展具有情境差异性、专业适应性和道德期望性的独特性,蕴含着深化、提升教师专业素养的基本理念,包括明晰交流轮岗教师的“新手—专家”型复合性角色、立足于交流轮岗对于专业发展的研修属性、践行交流轮岗专业服务均衡教育资源的伦理价值。交流轮岗促进教师专业发展的逻辑在于通过教育时空、对象的转变而对教师专业自主、知识、智慧形成挑战,诸如教师专业自主的构建与深化、专业知识的转化与再生、专业智慧的激活与创生。为此,需要通过教学实践落实均衡义务教育资源的专业伦理、构建教师交流轮岗的自我激励机制、提供支撑专业发展的教研活动平台。

轮岗教师乡土情感的缺失表征、根源及文化形塑

基于文化唯物主义理论视域,轮岗教师的乡土情感具有深刻意蕴,具体体现于:轮岗教师是认同乡村生活方式的“局内人”、是推动乡村学校发展的“同行者”、是担负乡村社会责任的“新乡贤”。目前,在轮岗交流实践中,存在着部分轮岗教师对乡村学校发展持“事不关己”态度、对乡村生活方式难以或不愿认同、乡村社会责任担当意识薄弱等问题。其原因在于:轮岗教师的教学岗位变动较频繁,乡村公共文化生活吸引力不足,轮岗教师对自身的角色认知不到位。对此,需要通过以下举措形塑轮岗教师的乡土情感:健全乡村学校组织文化,增强轮岗教师的“主人翁”意识;重构乡村公共文化生活,提升轮岗教师的乡土认同感;明确乡村社会文化身份,引导轮岗教师的责任行为。

气相旋转换热器壳程强化传热数值模拟

目前,针对大批量谷物干燥的换热器种类较少及现有换热器换热量小、换热效率和能源利用率低等问题,在前人研究的基础上改进了气相旋转换热器结构,并改变螺旋叶片螺距来强化壳程传热。采用计算流体力学软件FLUENT数值模拟方法,对气相旋转换热器壳程进行传热特性分析,得到气相旋转换热器壳程流场在两种螺距的螺旋叶片结构下的压力云图、温度云图和流体速度矢量图,并对比不同流量条件下以两种螺旋叶片螺距为变量的壳程压降、壳程出口温度。研究结果表明:在壳程进口流速为4m/s、进口温度为100℃工况下,对比螺旋叶片螺距为277.5mm及壳程螺距为412mm的螺旋叶片,壳程压降增加30.1%,努尔赛数提高为40.7%。

我国“县管校聘”教师流动政策的回顾与省思

我国“县管校聘”政策实施已十余年,历经“教师流动”与“县管校用”要素孵化、“县管校聘”政策落地发展两大阶段。基于多源流理论,本研究对“县管校聘”缘何从教师交流轮岗政策演变而成进行政策过程分析。研究发现:教师流动意愿与归属感“双低”、乡村教育新闻舆论聚焦点以及教师管理体制阻力难破为问题源流;各方建言献策、地方“县管校用”改革有成效为政策源流;学生家长诉求与教师配置问题矛盾突出、“努力办好人民满意的教育”“促进教育公平”执政理念为政治源流。三源流在耦合时机与动力“催化”下打开“县管校聘”政策之窗。据此建议增强问题意识、配套流动量化标准、补充评价考核机制、完善各项保障机制、考虑不同县(区)实施“县管校聘”的地方特殊性,同时加强乡村教育基础设施建设,以期“县管校聘”在各地实施更为合理、深入、有效。

长期不同施肥和深翻对玉米高粱轮作体系作物钾利用及土壤钾形态的影响

【目的】研究长期施用化肥钾、秸秆还田、有机肥配施化肥钾结合秸秆还田及其深翻对玉米高粱轮作体系作物钾利用效率、土壤钾形态及非交换性钾释放的影响,为合理使用钾肥和提高钾养分资源高效利用提供理论依据。【方法】于2011—2022年在山西省晋中市进行长期定位试验,共设6个处理:不施肥(CK)、氮磷肥(NP)、氮磷钾肥(NPK)、秸秆还田结合有机肥(MS)、氮磷钾肥配施有机肥结合秸秆还田(NPKMS)、氮磷钾肥配施有机肥结合秸秆还田和深翻(NPKMSD),研究不同施肥处理对作物籽粒产量、地上部钾吸收量、钾利用效率、土壤钾形态和土壤非交换性钾释放特征的影响。【结果】与NP和NPK比较,MS、NPKMS和NPKMSD提高籽粒产量6%—8%,地上部钾吸收量提高22%—43%。NPKMS和NPKMSD处理钾素农学利用效率仅为NPK和MS的50%;施肥改变了土壤剖面钾形态,2022年收获后与CK、NP和NPK处理相比,MS、NPKMS和NPKMSD处理0—20 cm土层速效钾含量分别提高了2.2—2.8倍,缓效钾提高了8%—10%;与NPKMS比较,NPKMSD提高了20—40 cm土层速效钾含量。基于随机森林回归模型分析表明,0—20和20—40 cm土层的速效钾与缓效钾含量能解释地上部钾吸收量的64.1%,0—20 cm土层速效钾、缓效钾含量和20—40 cm土层的速效钾含量是影响植株钾吸收的关键因子。用氯化钙浸提时NPK、MS、NPKMS和NPKMSD处理0—20 cm土层非交换性钾累积释放量分别是NP的1.04、1.77、1.99和1.81倍,柠檬酸浸提时则分别为1.05、1.41、1.85和1.63倍。与NPKMS处理比较,NPKMSD处理20—40 cm土层柠檬酸浸提的非交换性钾累积释放量提高17.8%,而氯化钙浸提对其非交换性钾累积释放量没有显著影响。【结论】与施用相当量的化肥钾比较,秸秆还田和有机肥能明显活化土壤钾,提高土壤有效钾和缓效钾的含量,提高钾肥利用效率。化肥钾配施有机肥结合秸秆还田会造成作物钾奢侈吸收降低钾利用效率。深翻提高根层下土层速效钾含量但对产量影响不显著。秸秆还田和有机肥明显促进土壤非交换性钾的释放速率和累积释放量,长期秸秆还田结合适量有机肥能够替代化学钾肥。

治理术视角下我国教师轮岗政策审视

福柯的治理术强调在自由平等的前提下,政府结合一定的治理手段或技术,引导个人行为,从外部支配走向内部自我管理。将治理术概念剖析与延伸,在其理论框架下,将25个省份教师轮岗政策文本进行社会性、法律性、人本性、文化性等四个维度的划分和内容审视,从中得出现阶段我国各省级教师轮岗政策存在社会性维度教师条件与社会需求脱节、法律性维度政策主体错位与政策工具法律性冲突、人本性维度主题需求与激励政策错位、文化性维度基本原则与政策工具文化性缺失,依据分析结论提出有助于提升教师轮岗政策合法性的建议,从而提高教师轮岗政策在合理配置优秀教师资源工作中的治理作用。

以问题为导向结合师生互换教学法在中医内科学分证论治教学中的应用

目的:探讨以问题为导向结合师生互换教学法对中医内科学分证论治教学效果的影响。方法:选择北京中医药大学2016级针灸康复专业的两个本科班为研究对象,选择“腹痛”和“肺胀”两个章节的分证论治部分进行教学。对照组采用传统教学法,试验组采用以问题为导向教学法和师生互换教学法相结合的教学方法。通过病例分析题目考试的方式,评估教学效果的差异。结果:试验组学生的优良率高于对照组学生(P<0.05);试验组学生考试成绩平均分数优于对照组学生(P<0.05)。结论:以问题为导向结合师生互换教学法在中医内科学分证论治部分的教学中能取得较好的效果。

组织支持感知对交流轮岗教师工作投入的影响——有调节的中介效应分析

教师交流轮岗政策实效性取决于教师工作效能的发挥和学校育人能力的提升,但交流轮岗教师所处“流出校-流入校”双重组织环境对于其工作投入的影响机制并不明确。基于工作要求-资源理论等,构建了组织支持感知与交流轮岗教师工作投入之间有调节的中介效应模型,并通过S市5个县区650名交流轮岗教师进行了实证检验。研究发现:组织支持感知对交流轮岗教师工作投入产生正向影响;交流轮岗教师对流出校和流入校的双重组织情感承诺链式中介了组织支持感知对其工作投入的影响。交流轮岗教师在流入校的内部人身份感知调节了感知组织支持与情感承诺间的关系。为提升交流轮岗教师的工作投入,需要多维度丰富交流轮岗教师工作资源、多主体参与交流轮岗教师服务管理、多角度提升交流轮岗教师身份感知。研究结果为提升交流轮岗教师工作投入,进而提高其教学效能和质量提供了改进的方向和路径,为“县管校聘”制度下构建“政府-流出校-流入校”的新型教师供给体系和联合管理服务体系提供了初步思考和启示。

Understanding the Outcomes of the China-England Mathematics Teacher Exchange:Observations ofa Shanghai Teacher

Highlights This study examines the China-England Mathematics Teacher Exchange program to identify and evaluate the differences in Chinese approach to mathematics education.There are numerous differences in terms of national mathematics curricula,organization of mathematics teaching,and evaluation objectives and methods due to different educational and learningcultures.China has made great achievements in mathematics education and student academic performance but has much to learn from England.

“三教”改革背景下教师教学创新团队建设路径的思考与实践——以建筑工程技术专业为例

打造高水平教师教学创新团队,是促进职业院校高质量发展的要求,也是深化教师队伍内涵建设的要求。要提升教师队伍的质量,就要立足于打造高水平“双师型”教师教学创新团队,注重教师能力的培养,创新改革教学模式,促进人才培养质量的提升。文章以贵州建设职业技术学院建筑工程技术专业聚焦教师内涵发展,着力建设高水平“双师型”教师教学创新团队为例,对团队建设过程中面临的问题与挑战进行反思,创新团队的建设路径,为建筑业转型升级培养更多的能工巧匠和技术技能人才,为行业发展提供人才保障。

Investigation of pressure wave behaviors in the rotational speed effects on a pressure-exchange wave rotor

A wave rotor is suitable for compact and efficient pressure-exchange between gas flows.This work measured the circumferential pressure distribution of the rotor/stator interfaces and utilized a CFD method to simulate the unsteady pressure waves.The experimental and CFD results showed some slopes in the circumferential pressure distributions,and the slopes indicated the traces of specific unsteady pressure waves.Such traces varied regularly if the rotational speed varied within a range from-11%to+11%off the baseline value,but they were seriously disturbed if the rotational speed varied by-45%from the baseline value.It verified that a pressure wave in a wave rotor tended to keep its pressure ratio and propagation velocity unchanged if the rotational speed varied by a small extent,and that the pressure wave could not keep its propagation patterns if the rotational speed varied by a large extent.Because of the pressure wave behaviors,the wave rotor demonstrated specific regulations of the rotational speed effects on its operational states.