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   26802篇
  免费   773篇
  国内免费   32篇
电工技术   330篇
综合类   13篇
化学工业   5936篇
金属工艺   516篇
机械仪表   465篇
建筑科学   1166篇
矿业工程   332篇
能源动力   650篇
轻工业   1735篇
水利工程   227篇
石油天然气   245篇
无线电   1719篇
一般工业技术   4087篇
冶金工业   6200篇
原子能技术   265篇
自动化技术   3721篇
  2022年   201篇
  2021年   410篇
  2020年   267篇
  2019年   345篇
  2018年   422篇
  2017年   367篇
  2016年   485篇
  2015年   390篇
  2014年   617篇
  2013年   1658篇
  2012年   939篇
  2011年   1201篇
  2010年   923篇
  2009年   972篇
  2008年   1153篇
  2007年   1067篇
  2006年   977篇
  2005年   884篇
  2004年   745篇
  2003年   716篇
  2002年   707篇
  2001年   490篇
  2000年   393篇
  1999年   450篇
  1998年   449篇
  1997年   434篇
  1996年   477篇
  1995年   444篇
  1994年   457篇
  1993年   441篇
  1992年   432篇
  1991年   272篇
  1990年   416篇
  1989年   390篇
  1988年   339篇
  1987年   409篇
  1986年   351篇
  1985年   445篇
  1984年   468篇
  1983年   400篇
  1982年   377篇
  1981年   300篇
  1980年   302篇
  1979年   361篇
  1978年   302篇
  1977年   246篇
  1976年   220篇
  1975年   246篇
  1974年   217篇
  1973年   225篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
This study develops a research method of assessing people's satisfaction with housing. Instead of the old approaches which consider in fragmented ways the characteristics of the dwelling, or the neighborhood, or the social environment, the author proposes a systems approach in which various interdependent factors are studied in relation to one another. Using the techniques developed, the relative satisfaction of tenants in public housing projects in certain areas of Canada is identified, analyzed, and discussed.  相似文献   
992.
993.
China is actively investigating ways to introduce project financing, specifically through the build-operate-transfer (BOT) scheme to meet the needs for the country's infrastructure and to be attractive to foreign investors and lenders. The advent of concession agreements, backed by new BOT laws, will be a positive move forward to achieving project-financed infrastructure projects. There are thus opportunities especially in the power sector for foreign investors. However, it is important to identify and manage the unique or critical risks associated with China's BOT projects. This is especially so after policies were introduced in late 1996 when the first state-approved BOT project, the US$650 million 2 × 350 megawatt (MW) coal-fired Laibin B Power Plant (Laibin B), was awarded. They include a competitive tendering process and 100% foreign ownership of the operating company. This paper is based on the findings from an international survey on risk management of BOT projects in developing countries, with emphasis on power projects in China. It discusses specifically the criticality of foreign exchange and revenue risks which include exchange rate and convertibility risk, financial closing risk, dispatch constraint risk and tariff adjustment risk. The measures for mitigating each of these risks are discussed also.  相似文献   
994.
All over the country community organizations are starting new community based businesses designed to fight unemployment, generate needed income, or respond to their own growth needs. This article addresses the questions of whether these new approaches can be used to plan and implement economic development efforts, what their political and ideological content is likely to be, what impact they will have on their neighborhoods, and what roles planners can play. The analysis is based on the authors' experiences as planners and technical assistants to such efforts, and on a detailed analysis of case studies.  相似文献   
995.
The magnitude and implications for the construction industry of reductions in carbon dioxide emissions that will ultimately be required globally and in industrialized countries are critically examined. As a result of the problem of climate change, these reductions are found to be in the region of 80–90% by 2050- much larger than those presently under discussion in national and global political fora. The technological feasibility of buildings with low energy requirements and low carbon emissions suggests that existing technology is capable of delivering reductions in this range. Unfortunately, the progress that is being made at the cutting edge is, with very few exceptions, not carried over into building stocks as a whole. Regulatory, fiscal and market-based policy and strategy mechanisms for improving the performance both of new build and the existing stock are critically examined. The achievement of meaningful reductions will require a coordinated and strategic approach, which makes use of the complementarity between these mechanisms. Regulation alone, in the absence of clear and consistent price signals provided through mechanisms such as carbon taxation, is unlikely to deliver the reductions in carbon emissions that will be needed to stabilize the global atmosphere and climate.

L'ampleur et les implications pour l'industrie de construction des réductions des émissions de dioxyde de carbone qui seront généralement exigées en fin de compte font l'objet d'un examen critque dans les pays industrialisés. Suite au problème des changements de climat, on a trouvé qu'en 2050 ces réductions d'émissions devraient se situer dans une zone de 80 à 90 % - c'est à dire, beaucoup plus grands que celle qu'on trouve dans les discussions et symposiums politiques nationaux et mondiaux. La faisabilité technologique de constructions nécessitant peu d'énergie et à faible émission de carbone suggére que la technologie actuelle est capable d'apporter des solutions à ces réductions. Malheureusement, à de rares exceptions prés, les progrés qui sont faits dans ces domaines de pointe ne sont pas appliqués dans leur totalité au secteur du bâtiment. La politique coordinatrice et fiscale, basée sur le marché ainsi que les mécanismes stratégiques visant à améliorer les performances concernant aussi bien les nouvelles constructions que celles existantes, sont examinés d'une façon critique. L'obtention de réductions significatives exigera une approche coordonnée et stratégique mettant en oeuvre ces deux mécanismes complémentaires. La seule réglementation, en l'absence d'arguments de prix clairs et cohérents comme par exemple la taxation sur l'oxyde de carbone, ne va vraisemblablement pas entrâner les réductions d'émissions de gaz carbonique qui seraient nécessaires afin de stabilizer l'atmosphère et le climat au niveau mondial.  相似文献   
996.
Self‐help housing in peri‐urban areas (usually outside municipal boundaries) is a feature, not only of rapidly urbanizing countries now in the South, but was also in Victorian England, where it was often initiated by freehold land societies, created by the Chartist movement in order to expand the franchise. These bodies bought and subdivided land for sale to their members, and laid out roads, using legal powers conferred upon the building societies. The societies made a significant contribution to housing for the urban working class, and preceded the garden city and town planning movement promoted by Liberal politicians. A case study is presented of one successful provincial society, the Ipswich and Suffolk Freehold Land Society.  相似文献   
997.
998.
Abstract

A SYMPOSIUM OF CURRENT PLANNING THEORY: Planning for America , By GEORGE B. GALLOWAY AND ASSOCIATES. Henry Holt and Co., New York; 713 pages, price $3.

A TEXTBOOK ON SUBDIVISION: Subdivision Regulations: An Analysis of Land Subdivision Control Practices. By HAROLD W. LAUTNER. Public Administration Service; 346 pages, price $3.75.

EMPLOYMENT IN THE REGIONAL DEVELOPMENT OF RESOURCES: Development of Resources and Stabilization of Employment in the United States. By THE NATIONAL RESOURCES PLANNING BOARD; 409 pages, price $1.20.  相似文献   
999.
Sir Peter Hall passed away at the age of 82 in July 2014. As a leading figure in the fields of planning, geography, urban regeneration, regional studies and transportation, numerous tributes and obituaries have already been published. In this memoir, Associate Editor Rob Freestone draws from his essay in the 2014 book which he co-edited with Mark Tewdwr-Jones and Nicholas Phelps, entitled The Planning Imagination: Peter Hall and the Study of Urban and Regional Planning (2014), to reflect on Peter's approach and contributions to the study of planning history.  相似文献   
1000.
A new approach to modelling probabilistic and stochastic engineering systems using graph theory is outlined. This approach emphasizes the introduction of probabilistic and stochastic concepts at the very beginning of the model building process. This is in marked contrast to past tendencies to add probabilistic concepts to the end of an otherwise deterministic model building process. The development of topological models founded on oriented probabilistic measurements is given. which leads to the identification of some useful statistical properties of the’ random interconnection equations’. The development of probabilistic component models is given, where a component can be characterized independently of other components. Methods for automatically building the second moment representation of the Mixed Nodal Tableau are discussed. The application of the above theory to the probabilistic analysis of a pipe network problem is briefly described.  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