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   541篇
  免费   37篇
  国内免费   7篇
电工技术   13篇
综合类   2篇
化学工业   144篇
金属工艺   11篇
机械仪表   24篇
建筑科学   21篇
矿业工程   2篇
能源动力   33篇
轻工业   45篇
水利工程   18篇
石油天然气   27篇
无线电   48篇
一般工业技术   70篇
冶金工业   9篇
自动化技术   118篇
  2024年   3篇
  2023年   9篇
  2022年   19篇
  2021年   44篇
  2020年   29篇
  2019年   39篇
  2018年   58篇
  2017年   28篇
  2016年   51篇
  2015年   25篇
  2014年   30篇
  2013年   55篇
  2012年   40篇
  2011年   36篇
  2010年   24篇
  2009年   22篇
  2008年   16篇
  2007年   13篇
  2006年   10篇
  2005年   8篇
  2004年   7篇
  2003年   5篇
  2002年   3篇
  2000年   1篇
  1998年   3篇
  1997年   2篇
  1996年   1篇
  1991年   1篇
  1989年   2篇
  1986年   1篇
排序方式: 共有585条查询结果,搜索用时 0 毫秒
41.
Egyptian mango seeds were collected as wastes from local fruit processing units and the kernels were separated and dried. This study was carried out on mango seed kernels to clarify their proximate composition, amino acids, phenolic compounds and the characteristics of the extracted oil including unsaponifiable matter constituents, lipid classes and fatty acid composition. Mango seed kernels contained a considerable amount of total phenolic compounds, total lipid, unsaponifiable matter, and a low amount of crude protein, but the quality of protein was good because it was rich in all essential amino acids. Eight phenolic compounds were identified; tannin and vanillin were in highest amounts. Unsaponifiable matter showed the occurrence of high amounts of squaline followed by sterols and tocopherols. Stearic acid was the main saturated fatty acid, while oleic acid was the major unsaturated fatty acid in all lipid classes. The fatty acid composition of total lipid and neutral lipid was similar, while phospholipid had a high amount of palmitic, linoleic and linolenic acids.  相似文献   
42.
采用机械合金化和热压工艺制备高强Al 7068?5%TiC(质量分数)纳米复合材料。基于致密化的重要性和晶粒生长的影响,以获得较高抗压强度为目标,采用Taguchi统计法对制备Al 7068?5%TiC块体纳米复合材料的热压条件进行优化。结果表明:在500 MPa和385°C下热压30 min能获得抗压强度为938 MPa、硬度为HV 265的Al 7068?TiC纳米复合材料。此外,方差分析结果表明,外加压力是影响纳米复合材料热压过程最关键的因素。各因素对纳米复合材料热压过程影响贡献率为外加压力(61.3%)、热压温度(29.53%)和热压时间(4.49%)。  相似文献   
43.
Utilizing response surface methodology, the conversion of vinyl chloride monomer (VCM) was monitored when the polymerization temperature, the type of surfactant, and the weight ratio of water‐to‐monomer (W/M) were taken as the emulsion polymerization variables. Because the homogeneous nucleation was found to be the dominant mechanism in VCM emulsion polymerization, irrespective of the surfactant concentration, the whole experiments have been carried out below critical micelle concentration of the used surfactants. Among all the studied variables, the polymerization temperature appeared as the most effective parameter; moreover, its interactive effect with W/M caused different trends in the alteration of final conversion being observed. Also, depending on the reaction temperature, the VCM conversion would be affected by the type of the surfactant used. Contrarily, simultaneous change in the type of surfactant and W/M revealed an insignificant effect on the evolution of VCM conversion. The optimization of final conversion of VCM was also accessible through contour plots of response surface methodology. It is worth noting that, taking a conventional approach into consideration, the alteration of VCM conversion seemed to be a monotonic function of temperature. J. VINYL ADDIT. TECHNOL., 21:157–165, 2015. © 2014 Society of Plastics Engineers  相似文献   
44.
In this paper, two Zigler-Natta catalysts (ZNCs) were used to synthesize a commercially available linear low-density polyethylene (LLDPE), widely used in the packaging industry, on an industrial scale. The catalysts differ only in their ability to distribute comonomers between short and long chains. Both catalysts were fully characterized in the first section, and two similar ethylene/1-butene copolymers were made using them. Afterward, the produced copolymers were fully characterized using different techniques; namely, differential scanning calorimetry (DSC), successive self-nucleation and annealing (SSA), oxygen induction time (OIT), melt flow index (MFI), rheometric mechanical spectroscopy (RMS), and a wide range of mechanical experiments. It was revealed that while the presence of comonomers in short chains can reduce their resistance against oxidation (by more than 30%) and can cause a dramatic change in friction coefficients (by more than 20%), some of the other main mechanical properties of the made copolymers were independent of comonomer distribution between long and short chains. In addition, it was shown that ethylenic copolymers' strain hardening modulus (SHM) takes advantage of the homogenous distribution.  相似文献   
45.
In this paper, we investigate the camera network placement problem for target coverage in manufacturing workplaces. The problem is formulated to find the minimum number of cameras of different types and their best configurations to maximise the coverage of the monitored workplace such that the given set of target points of interest are each k-covered with a predefined minimum spatial resolution. Since the problem is NP-complete, and even NP-hard to approximate, a novel method based on Simulated Annealing is presented to solve the optimisation problem. A new neighbourhood generation function is proposed to handle the discrete nature of the problem. The visual coverage is modelled using realistic and coherent assumptions of camera intrinsic and extrinsic parameters making it suitable for many real world camera based applications. Task-specific quality of coverage measure is proposed to assist selecting the best among the set of camera network placements with equal coverage. A 3D CAD of the monitored space is used to examine physical occlusions of target points. The results show the accuracy, efficiency and scalability of the presented solution method; which can be applied effectively in the design of practical camera networks.  相似文献   
46.
In this study, the central composite design of the response surface methodology was employed to investigate the effects of reaction temperature, catalyst concentration and cross flow circulation velocity on the production of biodiesel in a TiO2/Al2O3 membrane reactor. High‐quality palm oil biodiesel was produced by combination of alkali transesterification and separation processes in the ceramic membrane reactor. The optimum conditions for the conversion of palm oil to biodiesel in the ceramic membrane reactor were as follows: 70°C reaction temperature, 1.12 wt% catalyst concentration and 0.211 cm s? 1 cross flow circulation velocity. The physical and chemical properties of the produced biodiesel were determined and compared with the standard specifications. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   
47.
48.
The Arithmetic and Logic Unit (ALU) is a combination circuit that performs a number of arithmetic and logical operations within a microprocessor. The demand for faster and compact ALUs makes it desirable to test the ALU in conjunction with pre-design parts prior to manufacture. This may be accomplished in a process using CAD and SPICE simulation software. Our purpose is to realize a method for importing a layout drawn in Tanner L-edit and simulated in T-Spice into PSpice which is referred to as software talking. To do so we use an eight-function instruction set called Complimentary Metal Oxide Semiconductor Arithmetic and Logic Unit (CMOS ALU) which is laid out in Tanner L-edit and produces an extracted net-list which is simulated in T-Spice. An ALU equivalent design is then modeled in PSpice for further testing with pre-manufactured parts of the PSpice library.  相似文献   
49.
The Journal of Supercomputing - Scientific workflows are used to process large amounts of data and perform complex analyses; thus, they require powerful computing resources to produce the desired...  相似文献   
50.
Telecommunication Systems - Queueing models play a significant role in analysing the performance of power management systems in various electronic devices and communication systems. This paper...  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