New Developments in Water Efficiency     

Tony T. Gregg Amanda Dewees Drema Gross Bill Hoffman Dan Strub Matt Watson 《中国海洋大学学报(英文版)》2006,5(4):375-380

1Water LossInitiativesUnaccounted-for water(or unbilled water)has beenreceiving newscrutiny at both the state and nationallevels.For years,water conservationeffortsin Europehave emphasized reduction in water loss to a muchgreater extent thaninthe United S…  相似文献   

科学技术进步和现代经济地理学的方法论问题     

T.M.卡拉什尼科娃  李德美 《地理科学进展》1985,4(4):8-12

现在正是科学技术高速发展的时期,它必然引起劳动地域分工和生产地域组织的变化。研究经济问题的所有学科的研究对象也因而随着变化。促成这些变化的经济因素是。生产系统和非生产系统的形成;生产和非生产领域的高速发展;生产集中和地域集中;引用新工艺和新的劳动手段.  相似文献   

11颗类星体光谱(英文)     

陈建生  P.A.Shaver  I.J.Danziger 《中国天文和天体物理学报》1985,(4)

对天区0112-35的UKST物端棱镜底片上的11个类星体候选者进行了光谱观测,证实为类星体,给出了它们的红移值、证认图及光谱图。11个类星体中有6个属于角距小于4角分的3对类星体;1个类星体-星系对。  相似文献   

农田灌溉对亚洲西部地区环境的影响     

I.纳哈  孙仁华 《地理科学进展》1985,4(2):15-19

引言农田灌溉是一种最易提高干旱地区农业产量的方法。灌溉农业与旱作农业相比,谷物产量可提高6倍,根块植物产量可提高4—5倍。因此,农田灌溉在渴望得到更多粮食的干旱地区,可以发挥巨大的作用。农田灌溉使这些地区获得高产稳产,同时减轻了干旱和沙漠化的威胁。  相似文献   

半无限空间中SH波被空腔和刚性包体所散射(英文)     

曾心传  A.S.Cakmak 《大地测量与地球动力学》1985,(3)

根据波尔近似,借助于波动积分方程,近似求解半无限弹性空间中平面SH波由圆形空腔和刚性包体所散射的问题。获得了空腔表面上的散射位移、作用于被包体上的剪应力、半空间表面形变以及远场位移的近似公式。在数值计算中,ka(k=波数,a=空腔或被包体的半径)取为1.0,γ(SH波的入射角,从垂向方向起算)取为π/4。  相似文献   

美国地貌学情况综述     

J.E.科斯塔  云浦 《地理科学进展》1985,4(2):29-33

我们根据地貌工作者和第四纪地质学工作的人数、专业团体会员人数及其有关出版物等情况对美国地貌学家的活动状况做一个综述。美国的地貌学出现于19世纪末期。当时的地质学和地理学还紧密联系在一起的。当地理学成为一个独立学科时,其成员主要是自然地理学家和学过地质学的地貌学工作者。在本世纪30年代期间,地理学家们反对环境决定论的模式,地貌学的重要性有所下降。  相似文献   

A NEW“TETRASPORANGIAL”SPECIES OF LIAGORA(RHODOPHYTA,NEMALIALES)FROM HAWAIT     

Isabella A. Abbott 《中国海洋湖沼学报》1995,(4)

A new species of Liagora,L.perennis sp.nov.from Hawai’i,is described.Unlike dpecies of this genus in China,it is carpotetrasporangial,and at the place of expected carposporangia bears cruciately di-vided tetrasporangia,a detail which differentiates it from the usual species of Liagora without tetraspores that have been reported in China.Notes are provided on other Liagora species that have an impact on the taxonomy of species found in China.  相似文献   

The responses of different ethnic groups in the Sudan to rural-urban migration     

Ruppert H 《GeoJournal》1991,25(1):7-12

The ethnic identities of the various population groups in the Sudan are a product of their specific natural and social environments. The migration of these groups to the towns, especially to Greater Khartoum, involves a drastic change of cultural norms and values. However, the capability of change and the subsequent results are strongly conditioned by the specific background of each ethnic group and by the conditions in its area of origin. This is being proved by a comparative study on three ethnic groups in the Sudan: the Nuba, the Zaghawa and the Hadandawa.  相似文献   

Identification of the interstellar cyanomethyl radical (CH2CN) in the molecular clouds TMC-1 and Sagittarius B2     

Irvine WM  Friberg P  Hjalmarson A  Ishikawa S  Kaifu N  Kawaguchi K  Madden SC  Matthews HE  Ohishi M  Saito S  Suzuki H  Thaddeus P  Turner BE  Yamamoto S  Ziurys LM 《The Astrophysical journal》1988,334(2):L107-L111

We report the astronomical identification of the cyanomethyl radical, CH2CN, the heaviest nonlinear molecular radical to be identified in interstellar clouds. The complex fine and hyperfine structures of the lowest rotational transitions at about 20.12 and 40.24 GHz are resolved in TMC-1, where the abundance appears to be about 5 x 10(-9) relative to that of H2. This is significantly greater than the observed abundance of CH3CN (methyl cyanide) in TMC-1. In Sgr B2 the hyperfine structure is blended in the higher frequency transitions at 40, 80, and 100 GHz, although the spin-rotation doubling is clearly evident. Preliminary searches in other sources indicate that the distribution of CH2CN is similar to that for such carbon chain species as HC3N or C4H.  相似文献   

南极威尔克斯地SGR钻孔处雪冰转化过程中的密度变化特征          下载免费PDF全文

韩建康  N.W.杨 《极地研究》1988,1(1):13-24

本文着重描述了SGR钻孔处冰盖上的积雪在密实化过程中的特征变化,并对该过程进行了分段的和全面的回归分析.结果表明,冰盖密度随深度增大,但增长幅度随深度减小.作者提出密度变化减小度的概念.计算得出的所研究冰芯钻取点的密度变化减小度为-0.15kg/m~3·m~2,粒雪成冰前的密实速率平均值为4.08kg/m~3·a.本文得到的冰盖密度变化“临界点”与以往报道的有所不同.分析这一现象时,作者强调当积雪还在活动层时冰盖温度的影响,并以此解释密度剖面的异常变化以及离差的回升.特别指出,积雪的密度变化具有气候学意义,它在一定程度上能够反映出积雪形成及变化过程中气候变化的某些信息.本文由密度变化确定的钻孔点雪冰转化深度为50米.  相似文献