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郭永强  邵斌  王观虎  杨鑫  张晓义  张小小 《大地测量与地球动力学》2014,34(4):149-152

???????AutoCAD????????????????????????÷?????????????????????????????????????????????????????????VBA?????????????б?д???????????о?????????????????????κ????????????????????????????????????о??????????????????????????????????????λ?÷??????????????????÷???????????????á????????Ч???????????????????????????????????  相似文献   

电子航道图标准建设与应用     

罗睿  李晓雨 《测绘地理信息》2022,47(1):56-58

电子航道图的标准建设与生产应用关系到内河航运的高质量发展动能.分析了电子航道图标准的现状及存在的问题,建立了现有电子航道图标准体系及内河航道地理信息要素的分类方法,结合电子航道图核心要素,建立了典型应用场景,通过完善电子航道图数据标准体系和精细化生产应用,不断提升综合立体交通网的水运比较优势.  相似文献   

The method of feeding of lophophorates (bryozoa,phoronida, Brachiopoda)     

J. S. Bullivant 《新西兰海洋与淡水研究杂志》2013,47(1):135-146

The lophophorates all feed by “impingement” feeding, so named by analogy with certain types of particle separators used in industry.

In gymnolaemate bryozoans the feeding current is directed at the mouth where particles impinge and are sucked into the pharynx; in phylactolaemate bryozoans the particles impinge in the trough of the lophophore and are transported to the pharynx by cilia. In phoronids and brachiopods, particles impinge on the frontal surface of the tentacles and are conveyed to the pharynx by tracts of cilia.  相似文献   

机场净空GIS快速评定方法研究   总被引：1，自引：0，他引：1  

郭宽伟  岑国平  马文轩 《测绘科学》2012,(1):25-27

本文通过对机场净空规格进行分析,建立了机场净空区障碍物限制面的数学模型。在此数学模型的基础上使用ArcGIS、AutoCAD软件建立净空限制面三角网高程模型,并进行三维显示以及净空评定,为使用地理信息系统进行净空管理创造条件。  相似文献   

A record of hypolimnetic oxygen conditions in a temperate multi-depression lake from chemical evidence and chronomid remains     

Donna R. Francis 《Journal of Paleolimnology》2001,25(3):351-365

A multiproxy paleolimnological study of Douglas Lake, Michigan, was undertaken to elucidate the history of productivity and oxygen depletion in three basins of this multi-depression lake. Indicators investigated in three dated cores included chlorophyll a, Fe and Mn stratigraphy, and fossil chironomid assemblages. The coring sites were chosen to correspond to modern studies of oxygen depletion rates, and to determine if conclusions reached in these studies were supported by paleolimnological evidence. Stratigraphies of chlorophyll a, Fe and Mn indicate that two of the basins, South Fishtail Bay and Fairy Island, have been eutrophic and anoxic for a long period of time, predating European settlement. The third basin, Grapevine Point, has been consistently less productive, and had less severe oxygen depletion. Results of the chironomid analysis agree with these conclusions, including a change from mesotrophic to eutrophic indicator taxa in the Grapevine Point basin. All three cores show evidence of increasing trophic state in the most recent sediments, supporting some of the conclusions reached in the modern studies. It is also demonstrated that deforestation of the watershed had profound effects on littoral chironomid assemblages. Paleolimnological investigations also demonstrated the individual nature of the separate basins in Douglas Lake.  相似文献   

试论我国小直径钎具的锥体连接     

张汉斌 《地球科学》1992,17(6):739-747

中国年消耗锥体连接钎头1000万支以上,年消耗B_(22)、B_(25)锥体连接钎杆约15000t。针对中国钎具生产、使用部门在锥体连接问题上所存在的误解,结合修订和贯彻最新的钎头、钎杆国家标准GB6480t、GB6481,并参照国际标准ISO1718—1991,阐明了锥体连接的实质,充分论证了严格规定钎头锥孔和钎梢小端直径极限偏差值、孔底直壁间隙区、钎梢插深以及锥孔深度的必要性。这对减少钎具浪费、改善劳动条件、增强中国锥体连接钎具在国际市场的竞争能力,具重要的指导意义。  相似文献   

温度和微藻饵料对强额孔雀水蚤摄食的影响     

程浩楠  程方平  王淑红 《海洋科学》2021,45(3):24-32

论文以强额孔雀水蚤(Parvocalanus carssirostris)为研究对象,研究了不同培养温度(18℃、22℃、26℃、30℃)、不同种类微藻(球等鞭金藻(Isochrysis galbana)、牟氏角毛藻(Chaetoceros muelleri)、青岛大扁藻(Platymonas helgolandica...  相似文献   

Reviews     

《The Geographical journal》2000,166(2):174-188

Books reviewed:
Australia and New Zealand: Economy, Society and Environment. Reviewed by Terry Birtles
Global Environment Outlook 2000 – UNEP. Reviewed by Chris Park
Environment, Energy and Economy. Reviewed by Gordon Walker
Perspectives on British Rural Planning Policy 1994-1997. Reviewed by Richard Yarwood
Earth Surface Systems. Reviewed by Tony Parsons
Ecoviolence: Links Among Environment, Population, and Security. Reviewed by John Kirkby
Environment and Philosophy. Reviewed by Adrian Martin
Rehabilitation of Rivers: principles and implementation. Reviewed by Lindsey McEwen
Urban Growth and Development in Asia. Volume 1: Making the Cities. Volume II: Living in the Cities. Reviewed by Jonathan Rigg
The Hydrology of the Nile. Reviewed by Declan Conway
Geological Hazards: Their assessment, avoidance and mitigation. Reviewed by John Grattan
Living with the Unexpected: Linking Disaster recovery to Sustainable Development in Montserrat. Reviewed by David K. Chester
People, Land and Water in the Arab Middle East: Environments and Landscapes in the Bilâd ash-Shâm. Reviewed by Marianne Edwards
The Random Spatial Economy and its Evolution. Reviewed by Gordon L. Clark
Sustainable development in Central Asia. Reviewed by Jonathan Warner  相似文献   

The effect of salinity on clearance rate in the suspension-feeding estuarine gastropod Crepipatella dilatata under natural and controlled conditions   总被引：2，自引：1，他引：1  

O.R. Chaparro  Y.A. Montiel  C.J. Segura  V.M. Cubillos  R.J. Thompson  J.M. Navarro 《Estuarine, Coastal and Shelf Science》2008,76(4):861-868

The suspension-feeding gastropod Crepipatella dilatata occurs in estuaries in southern Chile that experience considerable fluctuations in salinity, driven by tidal and atmospheric forces. In the Quempillén estuary salinities as low as 9 psu may occur after severe rainstorms, and persist for several hours. In this study salinity was the major factor influencing the clearance rate of C. dilatata. At salinities below 20 psu, filtration ceased, whereas at high salinities (>22 psu) mean clearance rate was 0.24 l h⁻¹ standard animal⁻¹ (S.D. 0.18) for actively filtering individuals. This was confirmed by laboratory experiments under controlled conditions. Endoscopic observations were consistent with measurements of clearance rate, and showed that at salinity 25–30 psu the rate of transport along the gill filaments of particulate material embedded in mucus was 759 μm s⁻¹ (S.D. 480), but particle transport ceased at and below salinity 20 psu. Complete or partial isolation of the mantle cavity from the environment may be a mechanism to protect soft tissues and/or incubated egg capsules from osmotic stress.  相似文献   

Modeling Local Tidal Constituents Using TOPEX/POSEIDON SSH for the Malaysian Marine Region     

Muhammad Nur J. P. Vella  Sahrum Ses  Majid Kadir  Koji Matsumoto 《Marine Geodesy》2013,36(2):99-106

A new Local Ocean Tide Model, has been produced for the Exclusive Economic Zone (EEZ) of Malaysia, which incorporates some of the latest TOPEX/POSEIDON data for the years 1992 to 1998. Local tide gauge data are used as a comparison, along with another leading Global Ocean Tide Model, Ori96. The leading diurnal and semidiurnal constituents M₂, S₂, N₂, K₁, O₁, P₁ and Q₁ are reproduced using TOPEX/POSEIDON Sea Surface Heights (SSH) in a response analysis type least squares derivation following Munk and Cartwright (1966).  相似文献