期刊文献+
共找到99篇文章
< 1 2 5 >
每页显示 20 50 100
Required width of exit to avoid the faster-is-slower effect in highly competitive evacuation 被引量:3
1
作者 张玉春 马剑 +4 位作者 司有亮 冉桐 吴凡雨 王国元 林鹏 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第8期219-224,共6页
A group of competitive people escaping through an exit could lead to the formation of a deadlock, which significantly increases the evacuation time. Such a phenomenon is called the faster-is-slower effect(FIS) and i... A group of competitive people escaping through an exit could lead to the formation of a deadlock, which significantly increases the evacuation time. Such a phenomenon is called the faster-is-slower effect(FIS) and it has been experimentally verified in different systems of particles flowing through an opening. In this paper, the numerical simulation based on discrete element method(DEM) is adopted to study a group of highly competitive people through an exit of varying widths. The FIS effect is observed for a narrow exit whilst it is not observed for the exit wide enough to accommodate two people through it side-by-side. Experimental validation of such a phenomenon with humans is difficult due to ethical issues. The mouse is a kind of self-driven and soft-body creature and it exhibits selfish behaviour under stressed conditions.Particles flowing through an opening in different systems, such as pedestrian flow, animal flow, silo flow, etc. have similar characteristics. Therefore, experimental study is conducted by driving mice to escape through an exit of different widths at varying levels of stimulus. The escape time through a narrow exit(i.e., 2 cm) increases obviously with the increase of stimulus level but it is quite opposite to a wider exit(i.e., 4 cm). The FIS effect is avoided for an exit wide enough to accommodate two mice passing through it side-by-side. The study illustrates that FIF effect could be effectively prevented for an exit when its width is twice the size of particles. 展开更多
关键词 faster-is-slower effect DEM exit width highly competitive evacuation
原文传递
Development of adjustable permanent magnet Zeeman slowers for optical lattice clocks 被引量:3
2
作者 张晓航 徐信业 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第5期102-107,共6页
We develop a permanent-magnet Zeeman slower with adjustable magnets along the longitudinal and radial directions.Produced by four arrays of cylindrical magnets, the longitudinal magnetic field in the slower is tunable... We develop a permanent-magnet Zeeman slower with adjustable magnets along the longitudinal and radial directions.Produced by four arrays of cylindrical magnets, the longitudinal magnetic field in the slower is tunable if relevant parameters vary, for example, laser detuning or intensity. The proposed Zeeman slower can be reconfigured for Sr atoms. Additionally,we demonstrate that the residual magnetic field produced by the permanent magnets in the magneto-optical trap region can be as small as 0.5 Gs. 展开更多
关键词 permanent magnet slower adjustable longitudinal dipole tunable clock directions captured
原文传递
A Longitudinal Zeeman Slower Based on Ring-Shaped Permanent Magnets for a Strontium Optical Lattice Clock 被引量:4
3
作者 王强 林弋戈 +6 位作者 高坊林 李烨 林百科 孟飞 臧二军 李天初 方占军 《Chinese Physics Letters》 SCIE CAS CSCD 2015年第10期22-25,共4页
We report a longitudinal Zeeman slower based on ring-shaped permanent magnetic dipoles used for the strontium optical lattice clock. The Zeeman slower is composed of 40 permanent magnets with the same outer diameter b... We report a longitudinal Zeeman slower based on ring-shaped permanent magnetic dipoles used for the strontium optical lattice clock. The Zeeman slower is composed of 40 permanent magnets with the same outer diameter but different inner diameters. The maximum variation of the axial field from its target values is less than 2%. In most parts of the Zeeman slower, the intensity variations of the field in radial spatial distribution are less than 0.1 roT. With this Zeeman slower, the strontium atoms are slowed down to 95m/s, and approximately 2% of the total atoms are slowed down to less than 50m/s. 展开更多
关键词 A Longitudinal Zeeman slower Based on Ring-Shaped Permanent Magnets for a Strontium Optical Lattice Clock
原文传递
Static Stretching Combined with Conscious Slower Breathing May Increase Parasympathetic Activity and Reduce Stress in Adult Women
4
作者 Mami Sakurai Yasushi Ikarashi +3 位作者 Masahiro Tabuchi Ailing Hu Takuji Yamaguchi Hiroyuki Kobayashi 《Health》 2024年第3期242-256,共15页
Background: Women are thought to be more susceptible to stress than men in a stressful society, and reducing stress is crucial for women to maintain their health. Static stretching (SST) is applied in various fields t... Background: Women are thought to be more susceptible to stress than men in a stressful society, and reducing stress is crucial for women to maintain their health. Static stretching (SST) is applied in various fields to not only increase muscle flexibility but also reduce stress. Additionally, conscious slower breathing (CSB) predominates parasympathetic activity, causing a relaxing effect. These results indicate that combining SST and CSB may be more useful in reducing stress. However, to the best of our knowledge, the effect of this combination remains unclear. Objective: This study aimed to elucidate the effects of the combination of SST and CSB on autonomic activity and stress in adult women. Methods: Eleven healthy Japanese adult female participants performed SST with nonconscious natural breathing for 20 min. The same participants performed SST in combination with CSB (2 s inspiratory and 4 s expiratory) for 20 min on another day. Salivary cortisol and chromogranin A levels were measured before and after stretching as stress markers of the hypothalamic-pituitary-adrenal axis and sympathetic nervous system. The coefficient of variation of the R-R interval (CVR-R) and high-frequency component (HF), which reflect parasympathetic nerve activity, and heart rate and low-frequency component (LF)/HF ratio, which reflect sympathetic nerve activity, were measured before, during, and after stretching. Results: SST decreased cortisol levels but with no significant changes in chromogranin A, heart rate, CVR-R, HF, or LF/HF ratio. The combination of SST and CSB increased CVR-R and HF levels in addition to decreasing cortisol levels but with no significant changes in chromogranin A, heart rate, or LF/HF levels. Conclusion: These results indicate that the combination of SST and CSB may increase parasympathetic activity and reduce stress. However, future randomized controlled trials with larger sample sizes should support this conclusion. 展开更多
关键词 Static Stretching Conscious slower Breathing Autonomic Activity Heart Rate Variability STRESS
在线阅读 下载PDF
Outdoor Industry Expands Despite Slower Growth
5
作者 Richard Zhu 《China's Foreign Trade》 2015年第5期35-,共1页
Chinese outdoor industry is eyeing expansion in the future 10 years though its growth slows a little bit in recent years.China Outdoor Industry Report,released by China Outdoor Association(COA for short) at the Asia O... Chinese outdoor industry is eyeing expansion in the future 10 years though its growth slows a little bit in recent years.China Outdoor Industry Report,released by China Outdoor Association(COA for short) at the Asia Outdoor 2015 held in Nanjing,capital of Jiangsu Province in July,shows that the outdoor core market volume in 2014 reached RMB 17.06 展开更多
关键词 SHOW THAN Outdoor Industry Expands Despite slower Growth
在线阅读 下载PDF
Slower Growth the ‘New Normal’
6
《Beijing Review》 2018年第4期38-39,共2页
A nalysts predict that slower growth in China's money supply will become increasingly common amid the count,sdeleveraging efforts.
关键词 slower Growth the 'New Normal'
原文传递
SLOWER BUT HEALTHIER GROWTH
7
作者 LAN XINZHEN 《Beijing Review》 2010年第31期26-29,共4页
China maintains high GDP growth,low unemployment rate and low inflation against the backdrop of a fragile global economic recovery
关键词 GDP slower BUT HEALTHIER GROWTH
原文传递
Who are the slower fish among China's auto joint ventures?
8
作者 By GAO Heng (CATARC Beijing Operation) 《中国汽车(英文版)》 2002年第10期26-17,共2页
On Sept. 26, Chana Auto announced that by Sept. 23, after several rounds of selling-off which started at the beginning of 2002, Suzuki’s B shares in Chana, the second largest holding, were reduced to 61.4 million fro... On Sept. 26, Chana Auto announced that by Sept. 23, after several rounds of selling-off which started at the beginning of 2002, Suzuki’s B shares in Chana, the second largest holding, were reduced to 61.4 million from previous 122.5 million, accounting for only 5.003% of the whole. Some experts analyze there are two reasons behind the selling-off of Suzuki’s B shares of Chana: 1. Chana has been active recently in its cooperation with Ford (The initial investment of Chana Ford 展开更多
关键词 SHARES accounting selling cooperation HOLDING slower SUZUKI REASONS BEGINNING annually
原文传递
Textile Industry Recovery in First Half Tendency Continues Late Half with Slower Growth Speed
9
作者 Zhao Heming 《纺织服装周刊》 2010年第29期8-8,共1页
China National Textile & Apparel Council released the latest industry reviews in its mid-year conference that in the first half of 2010,the textile industry kept its stable recovery and the whole situation was goo... China National Textile & Apparel Council released the latest industry reviews in its mid-year conference that in the first half of 2010,the textile industry kept its stable recovery and the whole situation was good;for the anticipation of late half,this industry would continue this tendency but growth speed might slow down. 展开更多
关键词 over than Textile Industry Recovery in First Half Tendency Continues Late Half with slower Growth Speed down
原文传递
Chinese Economists’ Confidence Survey Economic Growth Was Expected to Be Slower and the Inflationary Pressure Was Still Quite High
10
《中国经济景气月报》 2008年第8期5-5,共1页
As shown in the results of 100 Chinese Economists’ Confi- dence Survey,conducted by China’s Economic Monitoring and Analy- sis Center,National Bureau of Statistics,the confidence index of the economists in the secon... As shown in the results of 100 Chinese Economists’ Confi- dence Survey,conducted by China’s Economic Monitoring and Analy- sis Center,National Bureau of Statistics,the confidence index of the economists in the second quarter of 2008 was 4.55 in the range of the values between 1 and 9.The survey indicated that,under the influence of the major factors such as the worsened international economic situations,the evident decline of the demand for export and the quite big inflationary pressure,etc,the economists had shown evidently deeper concem over the economic trend. 展开更多
关键词 Chinese Economists Confidence Survey Economic Growth Was Expected to Be slower and the Inflationary Pressure Was Still Quite High BE
原文传递
动物集体逃遁行为研究进展
11
作者 朱婷 李洁 +2 位作者 张健龙 杜澄举 王偲 《动物学杂志》 北大核心 2025年第3期463-474,共12页
集体逃遁行为是群居动物面对威胁时的一种复杂而迅速的群体反应,对于动物的生存至关重要。在开阔空间中,动物群体(如兽群、鸟群和鱼群)的运动受限较少,集体逃遁的关键在于个体之间的协调一致。而在封闭空间中,由于运动受限,动物需要竞... 集体逃遁行为是群居动物面对威胁时的一种复杂而迅速的群体反应,对于动物的生存至关重要。在开阔空间中,动物群体(如兽群、鸟群和鱼群)的运动受限较少,集体逃遁的关键在于个体之间的协调一致。而在封闭空间中,由于运动受限,动物需要竞争有限的出口和逃生路径,这往往导致个体表现出自私行为和从众行为,进而出现“快即慢”效应(单出口)和“对称性破坏”现象(双出口),降低了撤离效率。本综述重点探讨了不同动物类群在开阔和封闭空间中的集体逃遁行为和策略,并分析了影响撤离效率的关键因素,包括个体行为的一致性、群体规模、环境条件以及动物的生理特征。此外,本文还讨论了动物逃遁行为研究的前沿领域,并对未来的研究方向进行了展望,旨在为理解这一复杂现象提供更深入的视角。 展开更多
关键词 集群行为 逃遁 撤离效率 “快即慢”效应 影响因素
原文传递
^(87)Sr原子束的塞曼减速器磁场的研究 被引量:3
12
作者 王心亮 阮军 +3 位作者 马杰 郭文阁 任兆玉 张首刚 《时间频率学报》 CSCD 2008年第2期92-97,共6页
应用塞曼效应和多普勒冷却的理论,结合实验条件计算了87Sr原子束塞曼减速器的磁场。数值模拟给出了磁场线圈的层数、圈数、供电电流和其他参数,并据此制作了纺锤状线圈。测量结果表明,研制的纺锤状线圈的轴向磁场满足87Sr光晶格钟实验... 应用塞曼效应和多普勒冷却的理论,结合实验条件计算了87Sr原子束塞曼减速器的磁场。数值模拟给出了磁场线圈的层数、圈数、供电电流和其他参数,并据此制作了纺锤状线圈。测量结果表明,研制的纺锤状线圈的轴向磁场满足87Sr光晶格钟实验的要求。 展开更多
关键词 塞曼效应 多普勒频移 光钟 塞曼减速器
在线阅读 下载PDF
用于锶原子光钟永磁体塞曼减速器设计 被引量:3
13
作者 谢玉林 卢本全 +1 位作者 王叶兵 常宏 《时间频率学报》 CSCD 2014年第3期129-136,共8页
研究用于锶原子光钟的永磁体塞曼减速器,根据实验条件计算88Sr原子束塞曼减速器的磁场分布,将起始速度为410 m/s的锶原子减速至50 m/s,经过横向磁场的原子通量为7.9×105。基于永磁体制作的塞曼减速器,可靠性高、体积小、重量轻,磁... 研究用于锶原子光钟的永磁体塞曼减速器,根据实验条件计算88Sr原子束塞曼减速器的磁场分布,将起始速度为410 m/s的锶原子减速至50 m/s,经过横向磁场的原子通量为7.9×105。基于永磁体制作的塞曼减速器,可靠性高、体积小、重量轻,磁场分布可调,而且无需高电流和水冷装置,实现了永磁体塞曼减速器的小型化。 展开更多
关键词 原子冷却 多普勒频移 塞曼减速器
在线阅读 下载PDF
棉花品种对黄萎病慢病性初步研究 被引量:1
14
作者 简桂良 卢美光 王灿株 《棉花学报》 CSCD 北大核心 2005年第1期33-36,共4页
2002-2003年在河南省新乡县李台基地重病田,通过定株定时调查发病情况和各单株的产量结构,研究了不同抗病性棉花品种对黄萎病慢萎性。结果表明,若单纯以8月下旬的病情指数为标准,不少品种的抗病性均不理想,但从黄萎病发展历程分析,则发... 2002-2003年在河南省新乡县李台基地重病田,通过定株定时调查发病情况和各单株的产量结构,研究了不同抗病性棉花品种对黄萎病慢萎性。结果表明,若单纯以8月下旬的病情指数为标准,不少品种的抗病性均不理想,但从黄萎病发展历程分析,则发现有一部分耐至感病品种,其病情发展缓慢,对产量的影响也达不到显著水平。为此,提出棉花品种存在对黄萎病的慢病性,简称棉花品种慢萎性。 展开更多
关键词 黄萎病 棉花品种 抗病性 感病品种 单株 产量结构 病情指数 新乡县 初步研究 河南
在线阅读 下载PDF
利用Doppler测速法实现小发散角锶原子速度分布的测量 被引量:2
15
作者 谢玉林 韩建新 +1 位作者 卢本全 常宏 《量子光学学报》 北大核心 2016年第4期363-368,共6页
锶光钟小型化系统中,利用Doppler测速法对小发散角锶原子的速度分布进行了测量。从锶炉喷出原子束的最可几速率为440 m/s,经过永磁体塞曼减速器减速后原子的速度最低可降低至80 m/s。验证了在原子行进过程中设置的减速磁场即永磁体塞曼... 锶光钟小型化系统中,利用Doppler测速法对小发散角锶原子的速度分布进行了测量。从锶炉喷出原子束的最可几速率为440 m/s,经过永磁体塞曼减速器减速后原子的速度最低可降低至80 m/s。验证了在原子行进过程中设置的减速磁场即永磁体塞曼减速器,能够对原子进行有效减速,进而提高俘获冷原子的数目。实验中采用的Doppler测速法装置简单,易于操作,可直接探测原子束的速度分布曲线。 展开更多
关键词 小发散角 永磁体塞曼减速器 Doppler测速法
原文传递
Improved Evaluation of BBR and Collisional Frequency Shifts of NIM-Sr2 with 7.2×10^(-18)Total Uncertainty 被引量:6
16
作者 Bing-Kun Lu Zhen Sun +7 位作者 Tao Yang Yi-Ge Lin Qiang Wang Ye Li Fei Meng Bai-Ke Lin Tian-Chu Li Zhan-Jun Fang 《Chinese Physics Letters》 SCIE EI CAS CSCD 2022年第8期22-27,共6页
NIM-Sr2 optical lattice clock has been developed on the Changping campus of National Institute of Metrology(NIM).Considering the limitations in NIM-Sr1,several improved parts have been designed including a differentia... NIM-Sr2 optical lattice clock has been developed on the Changping campus of National Institute of Metrology(NIM).Considering the limitations in NIM-Sr1,several improved parts have been designed including a differential pumping stage in the vacuum system,a permanent magnet Zeeman slower,water-cooled anti-Helmholtz coils,an extended viewport for Zeeman slower,etc.A clock laser with a short-time stability better than 3×10^(-16)is realized based on a self-designed 30-cm-long ultra-low expansion cavity.The systematic frequency shift has been evaluated to an uncertainty of 7.2×10^(-18),with the uncertainty of BBR shift and the collisional frequency shift being an order of magnitude lower than the last evaluation of NIM-Sr1. 展开更多
关键词 PUMPING slower SHIFT
原文传递
Characterization of increased cuticular wax mutant and analysis of genes involved in wax biosynthesis in Dianthus spiculifolius 被引量:5
17
作者 Aimin Zhou Enhui Liu +3 位作者 Jiao Liu Shuang Feng Shufang Gong Jingang Wang 《Horticulture Research》 SCIE 2018年第1期384-392,共9页
Cuticular wax formation on the surface of plant leaves is associated with drought-stress tolerance.The identification of wax biosynthesis-related genes will contribute to the genetic improvement of drought resistance ... Cuticular wax formation on the surface of plant leaves is associated with drought-stress tolerance.The identification of wax biosynthesis-related genes will contribute to the genetic improvement of drought resistance in plants.In this study,we characterize a novel Dianthus spiculifolius mutant with increased cuticular wax.The mutant exhibited stronger drought resistance as indicated by less leaf wilting and death,higher leaf relative water content and water retention capacity,and slower water loss and chlorophyll extraction than did the wild type during drought treatment.In the mutant leaves,2730 upregulated and 2151 downregulated differentially expressed genes(DEGs)were identified by transcriptome sequencing.A wax biosynthesis pathway of the identified DEGs was significantly enriched.Finally,three key genes(DsCER1,DsMAH1,and DsWSD1)involved in wax biosynthesis were identified and verified by qPCR.These results suggest that differential expression of DEGs involved in wax biosynthesis may be associated with the increase in cuticular wax in the mutant.Taken together,our results help elucidate wax formation patterns in D.spiculifolius.Furthermore,the DEGs involved in wax biosynthesis identified here may be valuable genetic resources for improving plant stress tolerance through increased accumulation of cuticular wax. 展开更多
关键词 DROUGHT slower ANALYSIS
原文传递
鳙鱼肌肉胶原蛋白在低温贮藏中的变化 被引量:2
18
作者 黄海 曾名勇 《食品研究与开发》 CAS 北大核心 2009年第12期21-25,共5页
研究鳙鱼在-10、-20、-30和-40℃冻藏过程中胶原蛋白生化特性的变化。通过研究胶原蛋白的溶出量和采用SDS-PAGE法分析了鳙鱼在冻藏过程中的胶原蛋白变化情况。结果表明,胶原蛋白在冻藏过程中其溶出量呈波浪变化,但总体上是下降的。SDS-P... 研究鳙鱼在-10、-20、-30和-40℃冻藏过程中胶原蛋白生化特性的变化。通过研究胶原蛋白的溶出量和采用SDS-PAGE法分析了鳙鱼在冻藏过程中的胶原蛋白变化情况。结果表明,胶原蛋白在冻藏过程中其溶出量呈波浪变化,但总体上是下降的。SDS-PAGE的结果证实了胶原蛋白在冻藏过程中确实发生了降解。冻藏温度之间的差异是显著的(P<0.05)。冻藏温度越低,胶原蛋白变化越缓慢。 展开更多
关键词 鳙鱼 低温贮藏 胶原蛋白 生化特性
在线阅读 下载PDF
CD163 promotes hematoma absorption and improves neurological functions in patients with intracerebral hemorrhage 被引量:6
19
作者 Wen-jing Xie Hong-quan Yu +2 位作者 Yu Zhang Qun Liu Hong-mei Meng 《Neural Regeneration Research》 SCIE CAS CSCD 2016年第7期1122-1127,共6页
Clinical outcomes are positively associated with hematoma absorption.The monocyte-macrophage scavenger receptor,CD163,plays an important role in the metabolism of hemoglobin,and a soluble form of CD163 is present in p... Clinical outcomes are positively associated with hematoma absorption.The monocyte-macrophage scavenger receptor,CD163,plays an important role in the metabolism of hemoglobin,and a soluble form of CD163 is present in plasma and other tissue fluids;therefore,we speculated that serum CD163 affects hematoma absorption after intracerebral hemorrhage.Patients with intracerebral hemorrhage were divided into high-and low-level groups according to the average CD163 level(1,977.79 ± 832.91 ng/m L).Compared with the high-level group,the low-level group had a significantly slower hematoma absorption rate,and significantly increased National Institutes of Health Stroke Scale scores and modified Rankin Scale scores.These results suggest that CD163 promotes hematoma absorption and the recovery of neurological function in patients with intracerebral hemorrhage. 展开更多
关键词 hematoma intracerebral neurological hemoglobin NIHSS metabolism macrophage slower traumatic scavenger
暂未订购
厄尔尼诺事件产生的原因与验证 被引量:11
20
作者 杨学祥 《自然杂志》 北大核心 2004年第3期151-155,共5页
通过对 1 95 0~ 2 0 0 2年厄尔尼诺事件资料、地球自转速度变化资料、环南极海冰变化资料、臭氧变化资料、气候振动和大气环流准两年周期资料的模拟验证 ,我们发现地球自转速度减慢、赤道东太平洋表层海温升高、日食 -厄尔尼诺系数增... 通过对 1 95 0~ 2 0 0 2年厄尔尼诺事件资料、地球自转速度变化资料、环南极海冰变化资料、臭氧变化资料、气候振动和大气环流准两年周期资料的模拟验证 ,我们发现地球自转速度减慢、赤道东太平洋表层海温升高、日食 -厄尔尼诺系数增大与厄尔尼诺事件发生时间在一切细节上有惊人的对应关系 .这个综合检验结果给出了日食 -厄尔尼诺系数预测厄尔尼诺事件的有效性和准确性 .地球自转速度减慢、日食 展开更多
关键词 厄尔尼诺 地球自转速度 环南极海冰 臭氧 日食-厄尔尼诺系数
在线阅读 下载PDF
上一页 1 2 5 下一页 到第
使用帮助 返回顶部