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   74614篇
  免费   8426篇
  国内免费   4232篇
电工技术   12261篇
技术理论   14篇
综合类   5394篇
化学工业   8836篇
金属工艺   2595篇
机械仪表   3106篇
建筑科学   10105篇
矿业工程   2112篇
能源动力   12861篇
轻工业   2221篇
水利工程   1584篇
石油天然气   2192篇
武器工业   627篇
无线电   5433篇
一般工业技术   7727篇
冶金工业   3655篇
原子能技术   1381篇
自动化技术   5168篇
  2024年   505篇
  2023年   1689篇
  2022年   2721篇
  2021年   3005篇
  2020年   3187篇
  2019年   2830篇
  2018年   2403篇
  2017年   2852篇
  2016年   3188篇
  2015年   3117篇
  2014年   5178篇
  2013年   4981篇
  2012年   5412篇
  2011年   6089篇
  2010年   4674篇
  2009年   4729篇
  2008年   4274篇
  2007年   4714篇
  2006年   3711篇
  2005年   2886篇
  2004年   2398篇
  2003年   2055篇
  2002年   1808篇
  2001年   1550篇
  2000年   1329篇
  1999年   1065篇
  1998年   842篇
  1997年   665篇
  1996年   616篇
  1995年   452篇
  1994年   407篇
  1993年   326篇
  1992年   251篇
  1991年   227篇
  1990年   193篇
  1989年   159篇
  1988年   129篇
  1987年   94篇
  1986年   70篇
  1985年   105篇
  1984年   87篇
  1983年   54篇
  1982年   69篇
  1981年   34篇
  1980年   45篇
  1979年   27篇
  1978年   13篇
  1977年   14篇
  1976年   6篇
  1951年   11篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Full scale thermal storage tests were conducted in a room lined with PCM wallboard having latent heat storage capacity. The results were compared with those obtained from tests conducted in a similar room lined with ordinary wallboard. The research showed that PCM wallboard can function efficiently as a thermal storage medium which can be applied to peak load shifting, improved use of waste and solar heat as well as more efficient operation of heating and cooling equipment.  相似文献   
62.
Within the European Community, the interest in energy generation from biomass and waste is increasing. A brief overview is given of several thermal conversion technologies, of biomass production and waste availability in the Netherlands. Based on this, the possibilities for energy generation from biomass and waste in the Netherlands are evaluated.  相似文献   
63.
雾化水流计算模式   总被引:21,自引:1,他引:20  
本文描述了雾化水流现象并提出了雾化水流的一个计算模型。得出了雾化水流影响领域的各种不同的计算公式和方法。  相似文献   
64.
A restructured electricity system may undervalue renewable energy. We remain wary of unregulated markets, but urge the renewable energy community to begin considering how they could adapt to increasing customer choice.  相似文献   
65.
Two subroutines have been developed which permit users of the TRNSYS programme to calculate the parameters of ambiental comfort (PMV and PPD).The first subroutine deals with the calculation of the view factors inside a room for all the values of the spatial coordinates and, thus, permits the average radiant temperature to be calculated in every position. The second subroutine has been developed in accordance with the indications of the ISO 7730 standard.Both subroutines have been validated and then interfaced to TRNSYS.The integrated programme has been utilised to compare the performances of different heating systems in terms of energy consumption and comfort, maintaining the temperature of the interior constant for different climatic conditions.  相似文献   
66.
Standard Gibbs free energy of formation (ΔGf0), an important property needed in design calculations has been estimated using molar refraction, RM. The linear relationships derived between ΔGf0 and RM tested with the data on 8 series of hydrocarbons at 228 compounds yielded average deviations comparable to the methods cited in recent literature. The method can be used as an alternative to the existing ones, because of its simplicity combined with reasonable accuracy.  相似文献   
67.
本文主要论述了面流消能五种典型流态近底紊动流速特性,总结出了近底时均流速和紊动强度沿程变化规律,提出了近底紊动流速可能出现的最大瞬时值及相应位置的计算公式。面流消能工程的下游防冲设计中考虑的主要水力参数之一是,消能段近底流速紊动可能出现的最大瞬时值及其相应的部位,但目前国内外研究成果较少。笔者通过水工模型试验重点研究了面流消能各典型流态近底流速及其紊动纵向分量沿程的变化规律,并提出了计算公式,为优化面流设计提供科学依据。  相似文献   
68.
Jerzy   WIGO&#x 《Drying Technology》1996,14(2):271-288
Typical methods of dehumidification of air circulating in the dehumidifying driers (indirect and direct cooler and partial exchange of the air) were analysed. Energy aspect of cooler operation was evaluated. The method for minimization of unit thermal energy consumption in a dehumidifying drier by the optimal selection of the cooler point was also given. Methods of the heat recovery of heat conveyed in a cooler lending to save energy (heat regeneration. expansion and compression of the air, a dehumidifier) were analysed. It was indicated that introduction of dehumidifiers into contemporary wood driers caused significant improvement of energy aspects of their operation  相似文献   
69.
光催化氧化后四环素的分解率与COD去除率之间关系的探讨   总被引:1,自引:0,他引:1  
姜义华  胡岗 《太阳能学报》1996,17(3):231-234
以粉状无机半导体(ZnO)为催化剂,探讨了水溶液中四环素经光催化氧化分解率和COD去除率之间的关系。实验表明,在本实验中四环素的分解率和COD去除率之间有较好的正相关性。当反庆系统中有足量的活性催化剂和足够的光照时间时,绝大部分四环素将被较彻底地氧化分解成CO2,这不仅有助于光催化反应机理的研究,助于今后在环保中的实际应用。  相似文献   
70.
A demonstrative study for the wind and solar hybrid power system   总被引:1,自引:0,他引:1  
In March 1995, a small scale wind and solar hybrid power system was installed at Ashikaga Institute of Technology. Until now, the authors have acquired the data of the output of the hybrid power plant along with wind speed, wind direction, and the solar radiation, in order to demonstrate a complementary relationship between solar energy and wind energy.After nine months operation of the system, the authors confirmed that there exists a complementary relationship between solar energy and wind energy. We also found, however, that the power output by wind does not have much prospect compared to that by solar cell especially in summer season in Ashikaga area.  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