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   912篇
  免费   12篇
  国内免费   1篇
电工技术   5篇
综合类   16篇
化学工业   23篇
金属工艺   6篇
机械仪表   11篇
建筑科学   633篇
矿业工程   4篇
能源动力   16篇
轻工业   89篇
水利工程   7篇
石油天然气   2篇
无线电   9篇
一般工业技术   36篇
冶金工业   16篇
原子能技术   3篇
自动化技术   49篇
  2023年   7篇
  2021年   7篇
  2020年   12篇
  2018年   7篇
  2014年   8篇
  2013年   76篇
  2012年   15篇
  2011年   11篇
  2010年   6篇
  2009年   20篇
  2008年   9篇
  2007年   5篇
  2006年   9篇
  2005年   43篇
  2004年   30篇
  2003年   35篇
  2002年   44篇
  2001年   28篇
  2000年   47篇
  1999年   39篇
  1998年   44篇
  1997年   37篇
  1996年   39篇
  1995年   41篇
  1994年   42篇
  1993年   28篇
  1992年   39篇
  1991年   31篇
  1990年   20篇
  1989年   39篇
  1988年   22篇
  1987年   17篇
  1985年   4篇
  1984年   3篇
  1982年   2篇
  1980年   4篇
  1978年   4篇
  1977年   3篇
  1976年   3篇
  1975年   2篇
  1974年   4篇
  1973年   3篇
  1972年   2篇
  1969年   2篇
  1968年   4篇
  1967年   6篇
  1966年   2篇
  1965年   2篇
  1959年   2篇
  1958年   2篇
排序方式: 共有925条查询结果,搜索用时 187 毫秒
1.
This study, which is based on responses from over 300 individuals in England and Wales, explores how a willingness to use a water-recycling system of specific configuration varies against a number of factors which are linked to system design, system scale, system context, and water-conservation behaviour. Findings show that there is broad willingness to accept in-house water recycling provided that public health is not compromised.  相似文献   
2.
Anguilla is a UK overseas (non-independent) territory in the Caribbean. It is a small middle-income island with a population of 13 000, and recent statistics indicate that it is more dependent on tourism than any other country or territory in the world. Rapid population growth and development have placed more emphasis on the need for human health and environmental protection. For the first time, a systematic water-quality monitoring programme has been developed, based on the realities of the local situation, e.g. low resource base, limited capabilities, dependence on household rainwater catchment, storage cisterns, and a poor water-supply network. Development of the programme incorporated the key themes of pragmatic, realistic, incremental, responsive, and consultative approaches.  相似文献   
3.
The worldwide proliferation of fraudulent materials has brought about the need for a new approach to the control of purchased material quality. Nuclear power, defense, aerospace and many other industries are affected by the supply of poor quality clones that presume to be original replacement parts. Safety considerations abound as these highly defective materials are used in systems that are critical to the preservation of human lives. Commonly utilized quality assurance programs have not effectively stopped the influx of fraudulent materials. These programs fail to concentrate inspection efforts on materials and inspection attributes that would effectively prevent the acceptance of fraudulent materials. herein a solution is presented to this problem in the form of an expert system application. Information commonly available in industry is formulated into a knowledge based system wherein advisories are given to the user regarding key purchased material receipt inspection strategies.  相似文献   
4.
Water turbidity, surface temperature and circulation of Barton and Wroxham Broads, two of the Norfolk Broads, were studied using one reflective (TM1) and the thermal (TM6) TM band. The results indicated that the through-flowing path of the River Ant in Barton Broad is the major influence on the distribution of these parameters. In Wroxham Broad, both turbidity and surface temperature displayed a uniform distribution. This could be explained by the absence of a predominant direction of flow.  相似文献   
5.
During the day, there are considerable variations in the climatic factors prevailing in these regions. This is especially so during the 24-hour daily cycle of the long, hot and dry summer (mid-May to midOctober). Such climatic conditions have had a considerable impact on the daily living pattern of family life in the same season, particularly in the urban areas. During the same 24-hour cycle, they have compelled the inhabitants to shift their living activities both vertically in section and horizontally in plan; they do this in pursuit of more acceptable, if not, desirable internal thermal environmental ambience.  相似文献   
6.
7.
T he feasibility of treating a synthetic toxic waste and a petroleum refinery effluent was evaluated using a four-stage, fixed-film aerated bioreactor with a 50 I capacity and a surface area-to-volume ratio of 72. The process performance at various waste strengths and influent flow rates was found satisfactory.
Organic loading proved to be a better operational or design parameter. Treatment efficiency decreased as the loading was increased. An organic loading of 42 g COD/m2d or less is recommended to ensure good quality effluent. The reactor coped with organic and hydraulic overloads because of the good oxygen transfer capacity and the considerable quantity of attached biomass attained. Staging of the reactor was effective in damping excessive loadings.
Treatment of the refinery waste in the bioreactor removed up to 80 per cent of the COD and reduced the oil, sulphide and amm.N concentrations substantially, but polishing of reactor effluent using alum treatment improved effluent quality for potential reuse.  相似文献   
8.
This paper presents a Knowledge-based system (KBS) developed to allow users, who may not be knowledgeable about sensors, to select sensors suitable for their specific needs. The KBS runs on a micro-computer. The selection criteria are user specified and are based on the desired measurement parameters. The system output includes all of the operational and dimensional parameters of the recommended sensor, price, and vendor information.  相似文献   
9.
A modification of the well-known water-quality model 'quality simulation along river systems'(QUASAR) is presented in order to extend its ability, so that it may be considered applicable under unsteady-flow conditions. An aggregated dead-zone travel-time parameter, based on (a) the kinematic wave velocity (celerity) of the flow wave and (b) the behaviour of the solute within so-called 'dead zones', has been incorporated into the existing model formulation. This extends the current continuously-stirred tank reactor-based model process to account for the behaviour of solute under unsteady-flow conditions. The enhanced water-quality model has been validated by application to the Colorado River.  相似文献   
10.
This paper provides a detailed assessment of the microbiological quality of a selection of private water supplies. Samples were taken from 91 supplies and analyzed for total coliforms, faecal coliforms and faecal streptococci. The microbiological quality of the samples was generally poor, with almost 50% of the supplies failing to meet the required standards on at least one occasion. Given the high level of sanitary microbiological failures, there is the possibility that harmful microorganisms could be present and a significant risk to health cannot be discounted.  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