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   2315篇
  免费   164篇
  国内免费   22篇
电工技术   59篇
综合类   4篇
化学工业   625篇
金属工艺   54篇
机械仪表   102篇
建筑科学   104篇
矿业工程   4篇
能源动力   176篇
轻工业   191篇
水利工程   12篇
石油天然气   55篇
无线电   214篇
一般工业技术   444篇
冶金工业   85篇
原子能技术   24篇
自动化技术   348篇
  2024年   6篇
  2023年   48篇
  2022年   65篇
  2021年   135篇
  2020年   129篇
  2019年   157篇
  2018年   194篇
  2017年   192篇
  2016年   138篇
  2015年   111篇
  2014年   159篇
  2013年   252篇
  2012年   148篇
  2011年   193篇
  2010年   142篇
  2009年   104篇
  2008年   74篇
  2007年   51篇
  2006年   33篇
  2005年   22篇
  2004年   15篇
  2003年   15篇
  2002年   12篇
  2001年   16篇
  2000年   11篇
  1999年   8篇
  1998年   10篇
  1997年   13篇
  1996年   5篇
  1995年   8篇
  1994年   6篇
  1993年   1篇
  1992年   4篇
  1991年   1篇
  1990年   1篇
  1989年   1篇
  1988年   3篇
  1987年   5篇
  1986年   1篇
  1985年   2篇
  1982年   5篇
  1981年   1篇
  1980年   2篇
  1976年   2篇
排序方式: 共有2501条查询结果,搜索用时 19 毫秒
81.
Recently, nanocomposite photocatalysts based on semiconductors have attracted much attention due to their suitable bandgap. Combination of tow of several semiconductors can slow down the electron-hole recombination. In this regard, we have depicted an eco-friendly and green fabrication technique to synthesize RGO/Cu nanocomposite by the reduction of graphene oxide and Cu2+ ion utilizing spearmint extract as a reductant and capping agent. The sample was identified by FTIR, XRD, FESEM, EDS, HRTEM, and CV. The results of photocatalytic performance revealed that RGO/Cu is an efficient catalyst for degrading organic pollutants. This compound can eliminate Rhodamine B (RhB) and Methylene blue (MB) 91.0% and 72.0%, respectively.  相似文献   
82.
CuInS2/CuS nanocomposite were synthesized by a copper complex, [bis(ethylenediamine)copper(ΙΙ)] sulfate. Eight sulfur sources were used for this experiment. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis spectroscopy, and room temperature photoluminescence spectroscopy. Thin film of nanocomposite powder was fabricated and its feature (Voc, Jsc and FF) was calculated by current–voltage (I–V) curve.  相似文献   
83.
84.
The goal of Grid computing is to integrate the usage of computer resources from cooperating partners in the form of Virtual Organizations (VO). One of its key functions is to match jobs to execution resources efficiently. For interoperability between VOs, this matching operation occurs in resource brokering middleware, commonly referred to as the meta-scheduler or meta-broker. In this paper, we present an approach to a meta-scheduler architecture, combining hierarchical and peer-to-peer models for flexibility and extensibility. Interoperability is further promoted through the introduction of a set of protocols, allowing meta-schedulers to maintain sessions and exchange job and resource state using Web Services. Our architecture also incorporates a resource model that enables an efficient resource matching across multiple Virtual Organizations, especially where the compute resources and state are dynamic. Experiments demonstrate these new functional features across three distributed organizations (BSC, FIU, and IBM), that internally use different job scheduling technologies, computing infrastructure and security mechanisms. Performance evaluations through actual system measurements and simulations provide the insights on the architecture’s effectiveness and scalability.  相似文献   
85.
86.
87.
We propose a bi-objective cell formation problem with demand of products expressed in a number of probabilistic scenarios. To deal with the uncertain demand of products, a framework of two-stage stochastic programming model is presented. The proposed model considers minimizing the sum of the miscellaneous costs (machine constant cost, expected machine variable cost, cell fixed-charge cost, and expected intercell movement cost) and expected total cell loading variation. Because of conflicting objectives, we develop a two-phase fuzzy linear programming approach for solving bi-objective cell formation problem. To show the effectiveness of the proposed approach, numerical examples are solved and the results are compared with the two existing approaches in the literature. The computational results show that the proposed fuzzy method achieves lower objective functions as well as higher satisfaction degrees.  相似文献   
88.
In this paper, the impact of the mixture of sodium dodecyl sulfate (SDS) + multi-wall carbon nanotubes (MWCNTs) + β-cyclodextrin on the quantity and initial rate of methane dissolved in water is investigated. The experiments were performed at a temperature range of 278.15–303.15 K and an initial pressure of 0.5 MPa. The experimental results show that simultaneous utilization of β-cyclodextrin (0.01 mass fraction), MWCNTs (0.0005 mass fraction), and SDS (0.001 mass fraction) at 278.15 K increases the amount and the rate of methane dissolution in water by 29.90% and 173.78%, respectively, compared to pure water. An increase in the temperature decreases the quantity and the initial rate of methane dissolution in all solutions containing additives. However, no consistent relationship is observed between the temperature and the enhancement percentage of solubility of methane in solutions containing additives.  相似文献   
89.
Multimedia Tools and Applications - Constant increasing of visual information necessitates most efficient image compression schemes for saving storage space or reducing required transmission...  相似文献   
90.
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