全文获取类型
收费全文 | 15922篇 |
免费 | 339篇 |
国内免费 | 229篇 |
专业分类
电工技术 | 868篇 |
技术理论 | 1篇 |
综合类 | 332篇 |
化学工业 | 1860篇 |
金属工艺 | 440篇 |
机械仪表 | 621篇 |
建筑科学 | 1827篇 |
矿业工程 | 283篇 |
能源动力 | 4938篇 |
轻工业 | 208篇 |
水利工程 | 85篇 |
石油天然气 | 217篇 |
武器工业 | 33篇 |
无线电 | 1137篇 |
一般工业技术 | 1304篇 |
冶金工业 | 532篇 |
原子能技术 | 412篇 |
自动化技术 | 1392篇 |
出版年
2024年 | 29篇 |
2023年 | 294篇 |
2022年 | 430篇 |
2021年 | 542篇 |
2020年 | 466篇 |
2019年 | 420篇 |
2018年 | 395篇 |
2017年 | 435篇 |
2016年 | 573篇 |
2015年 | 535篇 |
2014年 | 897篇 |
2013年 | 879篇 |
2012年 | 770篇 |
2011年 | 1738篇 |
2010年 | 1213篇 |
2009年 | 1025篇 |
2008年 | 883篇 |
2007年 | 915篇 |
2006年 | 664篇 |
2005年 | 464篇 |
2004年 | 363篇 |
2003年 | 341篇 |
2002年 | 266篇 |
2001年 | 211篇 |
2000年 | 188篇 |
1999年 | 175篇 |
1998年 | 184篇 |
1997年 | 135篇 |
1996年 | 148篇 |
1995年 | 119篇 |
1994年 | 112篇 |
1993年 | 88篇 |
1992年 | 71篇 |
1991年 | 59篇 |
1990年 | 54篇 |
1989年 | 46篇 |
1988年 | 38篇 |
1987年 | 34篇 |
1986年 | 24篇 |
1985年 | 67篇 |
1984年 | 52篇 |
1983年 | 42篇 |
1982年 | 52篇 |
1981年 | 14篇 |
1980年 | 20篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1976年 | 2篇 |
1973年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
采用真空蒸发的方法交替沉积Ag和TCNQ分子制备了Ag TCNQ金属 有机络合物薄膜 ,并研究了多种外加电压激发下膜的电阻转变特性。发现在转变过程中存在着一种能量效应 ,即当外电压超过某一阈值后 ,完成转变的能量不变。对此现象的可能解释是薄膜内分子在一定的外部电场能量诱导下发生重排 ,致使电导率发生跃变 相似文献
62.
Robert M. Wirtshafter 《Energy Policy》1985,13(2):143-155
Utility conservation programmes are designed to benefit both participants and non-participants. This article outlines the issues involved in designing conservation programmes for utilities and determining the appropriate amount of incentives that can be provided to participants without harming non-participants. More importantly, the article discusses the issue of access to the programmes by utility customers. It concludes that it is the existing restrictions to participation, and not the level of compensation, that are of greatest concern to non-participants. A number of utility programmes designed to eliminate the problem of non-participation are reviewed. 相似文献
63.
Jean-Baptiste Lesourd 《Energy Economics》1985,7(3):138-144
It is shown that, when the mean productivity of some factors, such as energy or materials, is upperly bounded (a condition usually arising in energy production or in the process industries where energy takes part in physico-chemical processes), the production function may not be convex and, under some further conditions, is concave. Consequences of this model on the economics of energy savings are examined, and it is shown that energy savings may be considered at three levels: in the short run, by action on labour factors: in the medium run, by investment and action on labour factors; in the long run, by technological innovation, investment in new technologies and action on labour factors. Empirical findings along these lines are thus confirmed. 相似文献
64.
David Geltner 《Energy Policy》1985,13(4):340-344
The author examines the transport energy consumption of developing countries and compares it with that of developed countries. These figures are found to suggest considerable scope for transport energy savings. Given the need for improved energy efficiency, the author moves on to consider transport in the context of the wider economy. Four broad policy approaches which can affect transport energy consumption are identified — information and training programmes, subsidies; pricing and tax policies; and administrative regulations. The author's primary conclusion is that the energy price changes of the last decade do not hold revolutionary implications for the transport sector. There remains, however, a need to improve efficiency in this sector. 相似文献
65.
Susan Owens 《Energy Policy》1985,13(6):546-558
During the latter half of the 19ar 1970s there was great concern about potential conflicts over energy development proposals in the UK, most of which were expected to emerge within the framework of land use planning procedures and the associated opportunities for public participation. While there has been widespread dissatisfaction with the way in which the planning system handles energy developments, there is little consensus about the nature of the problem or about possible solutions to it. Greatly reduced energy forecasts allow a pause for reflection, but it is argued that there is no room for complacency about conflict over energy developments in future. 相似文献
66.
The rapid growth of Chinese economy has tremendously stimulated the expansion of energy consumption. The structure of energy consumption in China is featured with the coal domination. Air pollution is becoming increasingly severe. As a result, we are confronted with the extremely arduous task to balance energy consumption and environmental protection. In order to coordinate the relationship between energy consumption and environmental protection in a strategic way, this paper analyzes comprehensively the instruments, effects and perspectives of energy-related environmental management. Meanwhile, this paper illustrates the barriers and challenges facing the energy and energy-related environmental management in China, and suggests a priority strategy of management instrument, mainly composed of energy-saving, optimization of energy structure, promulgation of environmental standards, advance in environmental technologies, internalization of environmental costs, establishment of a public benefit fund and adoption of a Renewable Portfolio System. 相似文献
67.
第九次节能工作会议后,冶金工业掀起了节能降耗的新高潮。各企业都从本单位 实际出发,狠抓节能降耗工作,节能增效成绩显著。大中型钢铁生产企业全年节能350万t标煤,超 出1997年初冶金工作会议确定的全行业节能300万t目标。创造效益28亿元。 相似文献
68.
69.
70.
介绍了间断式半热滑轨的研制和应用过程,以及经过节能技术改造,用新型半热滑轨代替老式滑轨的使用。实践表明,不但解决了以往的水梁漏水的问题,而且使线C级品率提高了3.39%,每年可增产3500t线材,吨钢热涌单耗降低0.14GJ,年创经济效益239万元。 相似文献