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   20206篇
  免费   1840篇
  国内免费   865篇
电工技术   4796篇
综合类   1551篇
化学工业   2342篇
金属工艺   301篇
机械仪表   574篇
建筑科学   2416篇
矿业工程   867篇
能源动力   2343篇
轻工业   897篇
水利工程   646篇
石油天然气   730篇
武器工业   61篇
无线电   1107篇
一般工业技术   770篇
冶金工业   1683篇
原子能技术   31篇
自动化技术   1796篇
  2024年   65篇
  2023年   277篇
  2022年   562篇
  2021年   731篇
  2020年   707篇
  2019年   549篇
  2018年   528篇
  2017年   588篇
  2016年   740篇
  2015年   711篇
  2014年   1425篇
  2013年   1151篇
  2012年   1654篇
  2011年   1683篇
  2010年   1326篇
  2009年   1352篇
  2008年   1237篇
  2007年   1477篇
  2006年   1083篇
  2005年   946篇
  2004年   825篇
  2003年   719篇
  2002年   551篇
  2001年   490篇
  2000年   422篇
  1999年   261篇
  1998年   189篇
  1997年   145篇
  1996年   120篇
  1995年   103篇
  1994年   70篇
  1993年   59篇
  1992年   53篇
  1991年   30篇
  1990年   14篇
  1989年   9篇
  1988年   13篇
  1987年   8篇
  1986年   8篇
  1985年   2篇
  1984年   9篇
  1983年   4篇
  1982年   9篇
  1980年   1篇
  1977年   1篇
  1974年   1篇
  1967年   1篇
  1962年   1篇
  1951年   1篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
1.
王东 《水泥工程》2021,34(4):42-44
根据水泥烧成热耗的组成,降低高温设备表面散热是降低水泥烧成热耗的重要途径之一,而减少高温窑炉墙壁的热传导可有效降低设备的表面散热。本文在介绍无机内保温涂层隔热原理的基础上,对保温涂层的应用效果进行了对比研究,通过在传统耐火隔热材料的基础上增加新型无机内保温涂层,可有效降低高温设备外表面温度,减少水泥生产中的散热损失,达到节能降耗的目的。  相似文献   
2.
Residential natural gas consumption depends on several factors. Available tools and methods to identify, categorize, and validate effective factors have some limitations, making consumption modeling more complex. Once a comprehensive model of effective consumption factors is developed for residential gas consumers, it can predict consumption. In addition, such a model could be used to verify the accuracy of measuring devices in order to reduce unaccounted for gas (UFG). The key factors affecting residential gas consumption were identified based on previous studies and their mutual effects were analyzed using a fuzzy cognitive mapping (FCM) method. The most significant factors and their effects on natural gas consumption in the residential sector were determined. In this study, for the first time, the expected consumption for each consumer was estimated using a consumption index. Generally, if the estimated consumption is significantly different from the amount recorded by the meter, it could suggest a potential source of UFG. The proposed method was applied to the data collected from the residential gas consumers of a small region in Iran (Dasht-e Arjan region, Fars province), and the results demonstrate the effectiveness of the proposed method.  相似文献   
3.
分析了静电产生的原因,阐述了粉体含能材料生产中的静电起电现象、静电的危害、静电安全性评估标准以及建立在此标准基础上的静电放电危险的评价办法,提出了粉体含能材料在生产、运输中所需要采取的静电防护措施。  相似文献   
4.
《Oil and Energy Trends》2020,45(1):31-32
Current data on net electricity production, as well as a breakdown of production by country. Updated on a monthly basis.  相似文献   
5.
This paper investigates the relationship between economic growth, carbon dioxide (CO2) emissions, and energy consumption with an aim to test the validity of the Environmental Kuznets Curve (EKC) hypothesis in five ASEAN (Association of South East Asian Nations) countries (Indonesia, Malaysia, Philippines, Singapore, and Thailand) by applying the panel smooth transition regression (PSTR) model as a new econometric technique. The PSTR model is more flexible and appropriate for describing cross-country heterogeneity and time instability. Our empirical results strongly rejected the null hypothesis of linearity, and the test for no remaining nonlinearity indicated a model with one transition function and two threshold parameters. The first regime (levels of GDP per capita below 4686 USD) showed that environmental degradation increases with economic growth while the trend was reversed in the second regime (GDP per capita above 4686 USD). The results also showed that energy consumption with either the first or the second regime lead to increase CO2. The overall results support the validity of the EKC hypothesis in the ASEAN countries.  相似文献   
6.
An alternative Equivalent Electrical Circuit for Proton Exchange Membrane Fuel Cells is modelled in this study. Both I–V characteristics and H2 consumptions corresponding to generated power under load and no-load conditions are investigated. For this purpose, H2 consumptions and I–V characteristics of three different sized PEMFCs are tested. There is a very good harmony between the model results and measured values (relative error %0.7, %6.4 and %2.5 for FC-A, FC-B and FC-C respectively). In the proposed model current passes only on parallel resistance and not on serial resistance at no-load condition. Thus, a FC with higher parallel resistance should be preferred. Another key output of this study is that based on the proposed model, performance comparison of FCs can be performed with the parameters defined in this work. Proposals made in this study can easily be used for performance analysis of FCs under for both steady state and transient analysis.  相似文献   
7.
《Oil and Energy Trends》2019,44(10):29-30
Current data on net electricity production, as well as a breakdown of production by country. Updated on a monthly basis.  相似文献   
8.
《Oil and Energy Trends》2019,44(9):27-28
Current data on net electricity production, as well as a breakdown of production by country. Updated on a monthly basis.  相似文献   
9.
针对跨数据中心的资源调度问题,提出了一种基于组合双向拍卖(PCDA)的资源调度方案。首先,将云资源拍卖分为三个部分:云用户代理报价、云资源提供商要价、拍卖代理组织拍卖;其次,在定义用户的优先级及任务紧迫度的基础上,在拍卖过程中估算每一个工作发生的服务等级协议(SLA)违规并以此计算云提供商的收益,同时每轮竞拍允许成交多项交易;最终达到根据用户等级合理分配云资源调度的效果。仿真实验结果表明该算法保证了竞拍成功率,与传统一次拍卖成交一项的组合双向拍卖方案相比,PCDA在竞拍时间段产生的能耗降低了35.00%,拍卖云提供商的利润提高了约38.84%。  相似文献   
10.
The feasibility of microbial hydrogen consumption to mitigate the hydrogen embrittlement (HE) under different cathodic potentials was evaluated using the Devanathan-Stachurski electrochemical test and the hydrogen permeation efficiency η. The hydrogen permeation efficiency η in the presence of strain GA-1 was lower than that in sterile medium. The cathodic potential inhibited the adherence of strain GA-1 to AISI 4135 steel surface, thereby reducing the hydrogen consumption of strain GA-1. The adherent GA-1 cells were capable of consuming ‘cathodic hydrogen’ and reducing the proportions of absorbed hydrogen, indicating that it is theoretically possible to control HE by hydrogen-consuming microbes.  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