The Internet, mobile phone and space-time constraints   总被引：2，自引：0，他引：2  

Tim Schwanen  Mei-Po Kwan   《Geoforum》2008,39(3):1362-1377

While the implications of information and communication technologies (ICTs) for daily travel and activities have been studied extensively, there is only scant attention paid to the relations between ICTs and space-time constraints. This study therefore explores the extent to which the Internet and mobile phone increase the spatial and temporal flexibility of everyday activities through a review of the literature and empirical research with data from Columbus (Ohio, USA) and Utrecht (The Netherlands). The analysis suggests that the implications of the Internet and mobile phone are complex and dependent on the type of activity, persons involved, technologies and socio-physical context in which they are embedded. Various regularities can, however, be detected. For the study participants, the Internet and mobile phone relax temporal constraints to a stronger degree than they enhance spatial flexibility. There are also space-time constraints that seem to persist or have come about because of ICT adoption. Finally, it appears that the Internet and mobile phone at best consolidate differences between men and women in the space-time constraints associated with everyday activities.  相似文献   

PROSPECTING FOR THE HIDDEN ACTIVE FAULT BY MEASURING THE 218p0 AND 210p0          下载免费PDF全文

Zhang Yusong Hu Yutai Li Jianhua 《地震地质》1992,14(1):17

A method of prospecting for the concealed active fault by simultaneous measuring both 218Po and 210Po is introduced.It is a radioactive prospecting.The concentration of radon near the fault can be determined from the activities of its daughters 218Po and 210Po.At the fault,there is a good passage for gases,and the radioative gas from crustal depths can be easy to get to the surface.As a result,the level of the radioactivity there is quite high,but low at both sides far from there.The  相似文献   

长江三峡地区地壳形变特征及其构造意义   总被引：5，自引：1，他引：5  

李愿军 《地震地质》1991,13(3):249-257

本文讨论了三峡地区地壳形变特征,认为黄陵断块相对于周缘的差异性运动是存在的,最大年速率可达5—10毫米。跨断层的短水准结果以继承性断层活动为主,年速率在毫米级。水平形变网揭示仙女山断裂带近年来表现为左旋压扭性,天阳坪断裂带以右旋滑动为主  相似文献   

短滨螺Littorina brevicula排卵及运动潮汐节律性的研究     

薛钦昭 《海洋科学》1991,(4)

本文在室内无潮汐因子作用条件下对采集于青岛太平湾基岩海岸潮间带的短滨螺进行观察,发现其具有和潮汐同步的排卵和运动节律性。30d后,仍能观察到排卵的潮汐节律性。1a后,短滨螺不呈现排卵的潮汐节律性。  相似文献   

盐酸胍对文昌鱼Branchiostoma belcheri(Gray)酸性磷酸酯酶构象与活力的影响     

陈素丽  丁焱  陈灿和 《台湾海峡》1993,(4)

本文报告了文昌鱼酸性磷酸酯酶在不同浓度的盐酸胍作用下酶的构象与催化活力变化的关系。盐酸胍浓度在1mol/dm~3时,酶活力提高50%.随着盐酸胍浓度提高(2～4mol/dm~3),酶活力下降,荧光强度也下降,荧光发射光谱λ_(max)值明显红移(330～358nm)。测其变性及失活动力学常数,结果表明,酶的失活速度大于变性速度,表现为慢构象变化、快活力变化的一种模式。在盐酸胍3～4mol/dm~3时,酶的变性与失活过程表现为两个一级反应过程(快相和慢相),其构象与催化活力的变化表明AC-Pase 与活力部位相关的色氨酸残基微环境产生了变化。  相似文献   

云南巍山五里巷一茶雷村金矿地质及找矿方向     

董建春 《云南地质》2010,29(4):400-403

金矿赋存于挤压——滑脱构造破碎带中。成矿受构造、地层（岩性）、地球化学条件和围岩蚀变等条件控制。该区具有较大的找金潜力。  相似文献   

Activity of water during granulite metamorphism around Anakapalle,Vishakhapatnam District,A.P.     

S. N. Lal 《Journal of Earth System Science》1995,104(1):79-84

A refined mathematical equation is proposed to quantify the ambient activity of water during granulite fades metamorphism. The thermodynamic calculations point to the low activity of water during metamorphism in the area around Anakapalle, Vishakhapatnam district, A.P. Carbonic metamorphism seems to be responsible for the low activity of water during this metamorphism. Calc-silicate rocks in the area, could have been the source of the CO₂.  相似文献   

上海城市游憩者流动行为研究   总被引：165，自引：9，他引：165  

吴必虎 《地理学报》1994,49(2):117-127

由参与游憩活动的本地居民和外来游客共同构成城市游憩者。城市游憩者在空间上的流动规律将影响城市游憩设施和旅游资源的开发管理。通过旅行测定手段获得基本数据，运用游憩活动空间和使用曲线分析技术，研究上海城市游憩者的流动规律。  相似文献   

非水溶剂中电解质溶液活度系数的测定:NaCl在1,2-丙二醇中活度系数的测定   总被引：10，自引：3，他引：10       下载免费PDF全文

王卫东  向翠丽  胡珍珠  陆江林 《盐湖研究》2004,12(1):43-45

应用钠离子选择性电极和Ag-AgCl电极组成可逆电池,通过测定电池的电动势,应用Debye H櫣ckel极限公式,计算了不同温度下NaCl在1,2-丙二醇非水溶剂中的活度系数,并根据电解质溶液的溶剂化理论对NaCl的活度系数的某些变化规律进行了讨论。  相似文献   

Mobility of a remobilised parabolic dune in Kennemerland, The Netherlands   总被引：5，自引：0，他引：5  

S. M. Arens  Q. Slings  C. N. de Vries 《Geomorphology》2004,59(1-4):175

A parabolic dune in the Netherlands was remobilised in December 1998 by removing vegetation and soil. The main aim of the experiment was ecological: to investigate whether permanent rejuvenation at the landscape scale is possible by restoration of natural processes. If processes can be reactivated at coarse scale, periodic rejuvenation of the landscape over the long term is possible, without the need for managers to interfere further. The experiment provides the opportunity to address another important question: can large parabolic dunes in the Netherlands be mobile in the present climate? Mobility of the dune is investigated by means of erosion pins, aerial photography and measurement of cross sections. Activity indices are derived from erosion pin recordings and correlated to weather conditions. From 1999 to 2001, displacement of the dune ranged from 0 to 12 m in east–northeasterly direction. Activity of the dune is related to wind conditions, but the relationship is strongly influenced by precipitation and therefore differs for wet and dry periods. Periods with extreme wind speeds resulted in much less geomorphic change than expected.  相似文献