首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   232篇
  免费   34篇
  国内免费   8篇
测绘学   19篇
大气科学   18篇
地球物理   30篇
地质学   59篇
海洋学   82篇
天文学   1篇
综合类   20篇
自然地理   45篇
  2022年   6篇
  2021年   3篇
  2020年   6篇
  2019年   4篇
  2018年   5篇
  2017年   16篇
  2016年   13篇
  2015年   9篇
  2014年   9篇
  2013年   13篇
  2012年   8篇
  2011年   11篇
  2010年   7篇
  2009年   9篇
  2008年   21篇
  2007年   19篇
  2006年   15篇
  2005年   7篇
  2004年   8篇
  2003年   8篇
  2002年   4篇
  2001年   8篇
  2000年   3篇
  1999年   3篇
  1998年   2篇
  1997年   1篇
  1996年   3篇
  1995年   4篇
  1994年   4篇
  1993年   3篇
  1992年   2篇
  1991年   1篇
  1990年   2篇
  1989年   1篇
  1988年   3篇
  1987年   4篇
  1985年   10篇
  1984年   6篇
  1983年   9篇
  1982年   3篇
  1954年   1篇
排序方式: 共有274条查询结果,搜索用时 93 毫秒
61.
BOOK REVIEWS     
Books reviewed in this article: The Mexican Colonial Copper Industry. Elinore M. Barrett . The Control Revolution: Technological and Economic Origins of the Information Society . James R. Beniger . Land Degradation and Society . Piers M. Blaikie And Harold C. Brookfield , Eds . La carte, mode d'emploi. Roger Brunet . France: les dynamiques du territoire . Roger Brunet AND Jacques Sallois , EDS. At the Crossroads—The Mineral Problems of the United States . Eugene N. Cameron . A Census of One Billion People , Papers for International Seminar on China's 1982 Population Census. Li Chengrui , ED. Les Milieux “Naturels” du Globe . Jean Demangeot . The Geophysiology of Amazonia: Vegetation and Climate Interactions : Robert E. Dickinson , ED. Tenn-Tom Country . James F. Doster And David C. Weaver . Family Farming in Europe and America . Boguslaw Galeski And Eugene Wilkening , EDS. The Geography of Urban Transportation . Susan Hanson , Ed. Combating Desertification in Developing Countries . J. K. Jain , ED. Cartography in France—1660–1848. Science, Engineering and Statecraft . Josef W. Konvitz . Distribution of Distances in Pregeographical Space . Hans Kuiper . Physical Geography Lab Manual: A New Experimental Approach . Neal G. Lineback And John M. Harlin . Physical Geography: A Landscape Appreciation , 2nd ed. Tom L. Mc Knight . The Desert Is No Lady: Southwestern Landscapes in Women's Writing and Art . Vera Norwood And Janice Monk , EDS. France: A Geographical, Social, and Economic Survey . Philippe Pinchemel , translated, by D. Elkins and T. H. Elkins. Gene Banks and the World's Food . Donald L. Plucknett , Nigel J. H. Smith , J. T. Williams , And N. Murthi Anishetty . Latin American Development: Geographical Perspectives . David Preston , Ed. Making Sense of Development: An Introduction to Classical and Contemporary Theories of Development and Their Application to Southeast Asia . P. W. Preston . The History of the Countryside. Oliver Rackham . The Third World in Perspective . H. A. Reitsma AND J. M. G. Kleinpenning . The Industrial Geography of Australia . David C. Rich . The Recruiting Game , 2nd Ed., revised. John F. Rooney , JR. A Cultural Geography of North American Indians . Thomas E. Ross AND Tyrel G. Moore , EDS. Eastern Europe . Dean S. Rugg . Human Territoriality: Its Theory and History . Cambridge Studies in Historical Geography: 7. Robert David Sack . Experimental Fluvial Geomorphology . Stanley A. Schumm , M. Paul Mosley , AND William E. Weaver . The New Urban Landscape . David Schuyler . Atlas of American Women . Barbara Gimla Shortridge . Impacts of Hazardous Technology: The Psycho-Social Effects of Restarting TMI-1 . John Sorensen , Jon Soderstrom , Emily Copenhaver , Sam Carnes AND Robert Bolin . Modern Physical Geography , 3rd Ed., (Third Edition). Arthur N. Strahler AND Alan H. Strahler . India: Economic Resource Base and Contemporary Political Patterns . B. L. Sukhwal .  相似文献   
62.
63.
64.
To modernize food safety governance, we must carry out basic restructuring of its internal logic at the national level to reflect the features of contemporary Chinese society that shape food safety. This will entail establishing an overarching, macro-level conception of food safety that integrates “baseline safety”, “hub safety”, “co-constructed safety” and “endogenous safety”. These four dimensions of safety represent four fundamental requirements of food safety governance in modern Chinese society, which is a “risk society” (Beck 1992) and one that is also complex, open and pluralist. These requirements are: maximum legal liability, a unified, authoritative and efficient supervision system, a concept of social co-governance, and enterprises being the primary entities accountable for food safety. This article uses this analytical framework to interpret the basic contents of the newly revised Food Safety Law of the People’s Republic of China, and uses a focus on social co-governance to present the institutional highlights of this law and the transformation of the internal logic of food safety governance.  相似文献   
65.
湘澧盐矿区位于江陵凹陷南缘,该地区卤水中溴和钾的含量都达到了工业品位。对采集的湘澧盐矿卤水样品进行了化学全分析,并对分析的结果进行了研究,查明了卤水中钾和溴等元素的富集机理;提出关于卤水综合利用的工艺路线及可行性建议。等温蒸发实验表明,整个蒸发过程中均有石盐析出,失水量达到31.23%时,芒硝开始析出;此后,石盐和芒硝共同析出。整个蒸发过程中该卤水的析盐规律为,首先析出氯化钠,再析出硫酸钠,最后析出硫酸钾。  相似文献   
66.
This paper presents a study for linking remotely sensed data with property tax related issues. First, it discusses the key attributes required for property taxation and evaluates the capabilities of remote sensing technology to measure these attributes accurately at parcel level. Next, it presents a detailed case study of six representative wards of different characteristics in Dehradun, India, that illustrates how measurements of several of these attributes supported by field survey can be combined to address the issues related to property taxation. Information derived for various factors quantifies the property taxation contributed by an average dwelling unit of the different income groups. Results show that the property tax calculated in different wards varies between 55% for the high-income group, 32% for the middle-income group, 12% for the low-income group and 1% for squatter units. The study concludes that higher spatial resolution satellite data and integrates social survey helps to assess the socio-economic status of the population for tax contribution purposes.  相似文献   
67.
中国海与现代科学技术   总被引:5,自引:2,他引:5  
中国既是一个大陆国家又是一个海洋国家,约300万平方公里的海域与6500多个岛屿如同陆地资源一样为中国人民提供了舟辑之便与渔盐之利,还蕴藏着丰富的矿产资源。  相似文献   
68.
江苏省湿地资源丰富,湿地种类多样,分布广泛,但面临着严重的污染和破坏,且湿地立法相对分散,没有形成完整的湿地保护法律体系。《环境保护法》的修订,特别是生态红线、按日计罚、生态补偿、公益诉讼等制度设计,为江苏省湿地保护立法提供了强有力的制度支撑。在此情形下,制定"江苏省湿地保护条例"显得十分必要。  相似文献   
69.
We used a mixed-methods approach to assess the impact of a ‘forest-friendly’ titling program on previously untitled lands surrounding the Cuyabeno Reserve in Ecuador. Such programs are part of an increasing trend in tenure formalization intended to simultaneously strengthen tenure security, reduce deforestation, and open the door for more incentive-based conservation programs. We use quasi-experimental methods to estimate and compare the impact of titling on forest outcomes for lands that are titled with certain limitations on the ownership bundle of rights, alongside lands titled but without these restrictions. This quantitative analysis is paired with results from a series of focus group interviews with landowners to understand their experiences with the titling effort, particularly tied to the restrictions. Our results point to a statistically significant impact of titling with restrictions on reducing deforestation by 34%, whereas titling without such restrictions resulted in no significant effect. When we explore impacts according to annual deforestation rates, the results suggest that titled lands are buffered from the surges in deforestation that otherwise occurred on untitled lands and more broadly across the region. While ‘forest-friendly’ restrictions had more of an effect on forest outcomes than titled lands without, the insights shared by landowners suggest important concerns about equity and unjust burdens on current households that could risk livelihood options for future generations.  相似文献   
70.
The resonance phenomenon of fluid motions in the gap between ship section, seabed and vertical quay wall is studied numerically and experimentally. The natural frequency of the fluid motions in the gap is derived. A two-dimensional time-domain coupled numerical model is developed to calculate the non-linear wave forces acting on a ship section against vertical quay in a harbor. The fluid domain is divided into an inner domain and an outer domain. The outer domain is the area between the left side of ship section and the incident boundary, where flow is expressed by Boussinesq equations. The rest area is the inner domain, which is the domain beneath the ship section plus the domain between the right side of ship section and vertical quay wall. The flow in the inner domain is expressed by Newton's Second Law. Matching conditions on the interface between the inner domain and the outer domain are the continuation of volume flux and the equality of pressures. The numerical results are validated by experimental data.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号