基于翡翠的传播话黄龙玉的研究和开发     

王文景 《保山师专学报》2011,30(5):105-108

翡翠传播的历史就是翡翠从鲜为人知到广为接受再到辉煌、鼎盛的发展之路,而当今黄龙玉的兴盛和发展就是在重复翡翠已经走过的路。黄龙玉部分取代翡翠,成为玉器市场的新宠,是我国现阶段玉石（器）行业发展的一个新趋势。  相似文献   

农村劳动力转移培训的个案研究——对“云和师傅”培训的调查分析     

刘超 《职业技术教育》2011,(25)

云和师傅是云和县人民政府建立的具有本地特色的农村劳动力转移就业培训模式。其由云和县农村劳动力素质培训中心统一实施,主要分为后备云和师傅专业技能培训和云和师傅后续素质培训两种,培训领域涉及当地农业生产的多个行业,主要采用本地集中培训的模式。但其在发展过程中也表现出培训结构失调、模式单一、政府过度主导等问题,为此,其在未来发展中应重视对女性及偏远乡镇人口的培训、采用更加灵活的培训模式、增强对政府的监督。  相似文献   

马铃薯脱毒苗生产管理技术改良与应用研究     

杨振华 《杨凌职业技术学院学报》2011,10(1):9-12

利用茎尖脱毒生产脱毒种薯是解决马铃薯退化的根本性措施,本试验通过改良制定出新的马铃薯脱毒瓶苗生产工艺流程,从培养基制作、温度控制、瓶装苗及其污染控制、消毒灭菌和定期检查等方面研究了马铃薯脱毒苗快繁生产管理技术和脱毒苗扩繁技术关键,提出降低凭苗污染率和生长量的调控措施,使马铃薯脱毒瓶苗快繁技术应用更加完善和有效。  相似文献   

Dynamics and manipulation of ferroelectric domain walls in bismuth ferrite thin films     

Shuyu Xiao  Yaming Jin  Xiaomei Lu  Sang-Wook Cheong  Jiangyu Li  Yang Li  Fengzhen Huang  Jinsong Zhu 《国家科学评论(英文版)》2020,7(2):278

Ferroelectric domain walls differ from domains not only in their crystalline and discrete symmetry, but also in their electronic, magnetic, and mechanical properties. Although domain walls provide a degree of freedom to regulate the physical properties at the nanoscale, the relatively lower controllability prevents their practical applications in nano-devices. In this work, with the advantages of 3D domain configuration detection based on piezoresponse force microscopy, we find that the mobility of three types of domain walls (tail-to-tail, head-to-tail, head-to-head) in (001) BiFeO₃ films varies with the applied electrical field. Under low voltages, head-to-tail domain walls are more mobile than other domain walls, while, under high voltages, tail-to-tail domain walls become rather active and possess relatively long average lengths. This is due to the high nucleation energy and relatively low growth energy for charged domain walls. Finally, we demonstrate the manipulation of domain walls through successive electric writings, resulting in well-aligned conduction paths as designed, paving the way for their application in advanced spintronic, memory and communication nano-devices.  相似文献   

黄河流域土地利用时空格局演变及驱动力   总被引：10，自引：0，他引：10  

张佰发  苗长虹 《资源科学》2020,42(3):460-473

土地利用时空格局是人类与自然相互作用状况的重要表征。研究黄河流域土地利用时空格局及其驱动因素,厘清土地利用类型转换及粮食保障用地、生态保育用地、城乡建设用地的时空变化特征,可为黄河流域生态保护和高质量发展国家重大战略的规划制定与实施提供参考。本文基于土地利用类型转移矩阵和空间自相关,从城市群、省、市、县多尺度入手,利用7期土地利用数据对黄河流域1970—2015年土地利用状况及变化进行探究。结果表明：①黄河流域生态保育用地和耕地占比多年平均值分别为79.04%和18.64%,表明生态保护和粮食生产是其两大主体功能;②城乡建设用地占比逐年提高,城市群地区是建设用地扩张的主体空间;③黄河流域耕地、生态保育用地和城乡建设用地各节点年份Moran’s I均大于0.75,表明3种功能类型用地具有强空间正向集聚效应,呈现出“凹”字型分布格局;④城乡建设用地扩张以牺牲耕地为代价,同时部分农村居民点用地逐渐转化为城镇用地;⑤人口规模和经济发展是促进土地利用变化的核心因素,驱动力因素存在区域差异,在黄河下游的山东、河南,经济水平达到一定规模后,伴随经济再发展不会出现大规模城乡建设用地扩张。  相似文献   

Effects of oncoming target velocities on rapid force production and accuracy of force production intensity and timing     

Yoichi Ohta 《Journal of sports sciences》2017,35(23):2304-2312

The present study aimed to clarify the effects of oncoming target velocities on the ability of rapid force production and accuracy and variability of simultaneous control of both force production intensity and timing. Twenty male participants (age: 21.0 ± 1.4 years) performed rapid gripping with a handgrip dynamometer to coincide with the arrival of an oncoming target by using a horizontal electronic trackway. The oncoming target velocities were 4, 8, and 12 m · s^?1, which were randomly produced. The grip force required was 30% of the maximal voluntary contraction. Although the peak force (Pf) and rate of force development (RFD) increased with increasing target velocity, the value of the RFD to Pf ratio was constant across the 3 target velocities. The accuracy of both force production intensity and timing decreased at higher target velocities. Moreover, the intrapersonal variability in temporal parameters was lower in the fast target velocity condition, but constant variability in 3 target velocities was observed in force intensity parameters. These results suggest that oncoming target velocity does not intrinsically affect the ability for rapid force production. However, the oncoming target velocity affects accuracy and variability of force production intensity and timing during rapid force production.  相似文献   

合理使用与许可使用的异同及适用     

刘志刚 《图书馆建设》2005,(5):1-4

版权法自产生之初,就在对版权是保护还是限制这个问题上陷入两难境地。一方面要鼓励和保护优秀作品的创作与传播;另一方面必须出于对社会公共利益的兼顾而对版权人权利加以限制。总的来看,这种限制主要包括合理使用和许可使用两个方面。  相似文献   

浅论邓小平对青少年成长的关怀     

周慧敏 《六盘水师范高等专科学校学报》2004,16(5):33-34

邓小平同志始终以博大的胸怀和深邃的目光,站在党和国家前途命运的高度,十分关怀青少年的成长。多次向青年发出号召要做“四有”新人,要学习,要参加社会实践,并鼓励大量派遣青少年出国留学,培养了大量的青年专家。  相似文献   

Impact absorption of tennis shoe-surface combinations     

S.?J.?DixonEmail author  V.?H.?Stiles 《Sports Engineering》2003,6(1):1-9

The aim of this study was to investigate, for typical shoes and surfaces used in tennis, the relative role of the shoe and surface in providing cushioning during running. Five test surfaces ranging from concrete to artificial turf were selected, together with two shoe models. Impact absorbing ability was assessed mechanically using drop test procedures and biomechanically using peak magnitude and rate of loading of impact force and peak in-shoe pressure data at the lateral heel. Differences in biomechanical variables between shoe-surface combinations were identified using a two-way ANOVA (p < 0.05). Mechanical test results were found to rank the surfaces in the same order regardless of the shoe model, suggesting that the surface is influential in providing cushioning. However, for all mechanical and biomechanical (p < 0.05) variables representing impact absorbing ability, it was found that the difference between shoes was markedly greater than the differences between surfaces. The peak heel pressure data were found to rank the surfaces in the same order as the mechanical tests, while impact force data were not as sensitive to the changes in surface. Correlations between mechanical and biomechanical impact absorption highlighted the importance of testing the shoe-surface combination in mechanical tests, rather than the surface alone. In conclusion, mechanical testing of the shoe-surface combination was found to provide a strong predictor of the impact absorbing ability during running if pressure data were used. In addition, for typical shoe-surface combinations in tennis, the shoe was found to have more potential than the surface to influence impact loading during running. Finally, in-shoe pressure data were found to be more sensitive than force plate data to changes in material cushioning.  相似文献   

大型集装箱船的总纵强度实用计算方法     

吴善刚  邱文昌 《上海海事大学学报》1998,(3)

以我国１９９６年《钢质海船入级与建造规范》对大型集装箱船的总纵强度的要求为标准,讨论了具体装载状态下船舶总纵强度的校核方法,并着重探讨了在资料不完整的情况下与总纵强度校核有关的船舶资料的计算制作方法。  相似文献