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   262篇
  免费   11篇
电工技术   7篇
化学工业   42篇
金属工艺   3篇
机械仪表   3篇
建筑科学   22篇
能源动力   12篇
轻工业   32篇
水利工程   5篇
石油天然气   1篇
无线电   31篇
一般工业技术   27篇
冶金工业   30篇
自动化技术   58篇
  2024年   1篇
  2023年   5篇
  2022年   2篇
  2021年   13篇
  2020年   7篇
  2019年   7篇
  2018年   10篇
  2017年   2篇
  2016年   7篇
  2015年   12篇
  2014年   11篇
  2013年   9篇
  2012年   8篇
  2011年   22篇
  2010年   15篇
  2009年   12篇
  2008年   22篇
  2007年   12篇
  2006年   7篇
  2005年   12篇
  2004年   5篇
  2003年   3篇
  2002年   12篇
  2001年   4篇
  2000年   4篇
  1999年   6篇
  1998年   8篇
  1997年   4篇
  1996年   1篇
  1995年   5篇
  1994年   2篇
  1993年   1篇
  1992年   2篇
  1991年   1篇
  1988年   2篇
  1986年   1篇
  1984年   2篇
  1983年   1篇
  1982年   2篇
  1979年   1篇
  1978年   2篇
  1977年   2篇
  1976年   2篇
  1975年   1篇
  1970年   1篇
  1969年   1篇
  1968年   1篇
排序方式: 共有273条查询结果,搜索用时 0 毫秒
81.
Sigmund Freud and B. F. Skinner are often seen as psychology's polar opposites. It seems this view is fallacious. Indeed, Freud and Skinner had many things in common, including basic assumptions shaped by positivism and determinism. More important, Skinner took a clear interest in psychoanalysis and wanted to be analyzed but was turned down. His views were influenced by Freud in many areas, such as dream symbolism, metaphor use, and defense mechanisms. Skinner drew direct parallels to Freud in his analyses of conscious versus unconscious control of behavior and of selection by consequences. He agreed with Freud regarding aspects of methodology and analyses of civilization. In his writings on human behavior, Skinner cited Freud more than any other author, and there is much clear evidence of Freud's impact on Skinner's thinking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
82.
83.
We study a dynamic optimization problem arising in the (long-term) planning of road rehabilitation activities. In this area one seeks a pavement resurfacing plan for a road network under budget constraints. Our main approach is to model this as an integer programming problem with underlying dynamic programming structure. We investigate properties of this model and propose a solution method based on Lagrangian relaxation where one gets subproblems that are shortest path problems. Some computational experiences based on realistic data are reported.  相似文献   
84.
By analogy with the representation of the polarization of light on the Poincaré sphere, we describe the propagation and the reflection/transmission of light in a multilayer on a hyperbolic surface. We show that the propagation of light corresponds to a classical rotation on this surface and that its reflection/transmission corresponds to a hyperbolic rotation.  相似文献   
85.
The uptake of specific fatty acids in humans is dependent on their position on the glycerol backbone. There is a great interest in methods that can access this information fast and accurately. By way of high-resolution NMR, we have analyzed TAG extracted from pig and beef tissues and obtained quantitative data for the composition and regioisomeric distribution of all major unsaturated fatty acids usually found in these source materials, using a combination of manual integration and deconvolution of 13C NMR spectra. In addition, we have developed a method for determining composition and regioisomeric distribution of the two main saturated fatty acids found in pork (16:0, 18:0). The results are discussed in relation to species-specific genetic characteristics of fatty acid and TAG biosynthesis. The developed method could support decisions related to breeding for desired fatty acid profiles, and stimulate further methodology developments using high field NMR.  相似文献   
86.
This paper compares the techno-economic performances of three technologies for CO2 capture from a lignite-based IGCC power plant located in the Czech Republic: (1) Physical absorption with a Rectisol-based process; (2) Polymeric CO2-selective membrane-based capture; (3) Low-temperature capture. The evaluations show that the IGCC plant with CO2 capture leads to costs of electricity between 91 and 120 €·MWh−1, depending on the capture technology employed, compared to 65 €·MWh−1 for the power plant without capture. This results in CO2 avoidance costs ranging from 42 to 84 €·tCO2,avoided−1 , mainly linked to the losses in net power output. From both energy and cost points of view, the low-temperature and Rectisol based CO2 capture processes are the most efficient capture technologies. Furthermore, partial CO2 capture appears as a good mean to ensure early implementation due to the limited increase in CO2 avoidance cost when considering partial capture. To go beyond the two specific CO2-selective membranes considered, a cost/membrane property map for CO2-selective membranes was developed. This map emphasise the need to develop high performance membrane to compete with solvent technology. Finally, the cost of the whole CCS chain was estimated at 54 €·tCO2,avoided−1 once pipeline transport and storage are taken into consideration.  相似文献   
87.
88.
Lithium–sulfur batteries (LSBs) are regarded as a new kind of energy storage device due to their remarkable theoretical energy density. However, some issues, such as the low conductivity and the large volume variation of sulfur, as well as the formation of polysulfides during cycling, are yet to be addressed before LSBs can become an actual reality. Here, presented is a comprehensive overview illustrating the techniques capable of mitigating these undesirable problems together with the electrochemical performances associated to the different proposed solutions. In particular, the analysis is organized by separately addressing cathode, anode, separator, and electrolyte. Furthermore, to better understand the chemistry and failure mechanisms of LSBs, important characterization techniques applied to energy storage systems are reviewed. Similarly, considerations on the theoretical approaches used in the energy storage field are provided, as they can become the key tool for the design of the next generation LSBs. Afterward, the state of the art of LSBs technology is presented from a geopolitical perspective by comparing the results achieved in this field by the main world actors, namely Asia, North America, and Europe. Finally, this review is concluded with the application status of LSBs technology, and its prospects are offered.  相似文献   
89.
In spite of their relatively poor gamma-ray stopping efficiencies, the Geiger-Müller (GM) counter is still preferred in many radioisotope gauges for industrial measurements. This is because these detectors exhibit a high degree of robustness in harsh environments, are relatively insensitive to temperature changes in the environment, and are inexpensive compared to other types of radiation detectors. These properties could make the use of GM counters very feasible in a number of industrial applications, such as gamma-ray tomography and gamma-ray density gauges, provided that their gamma-ray stopping efficiencies can be improved. The Monte Carlo (MC) method is a powerful computational physics tool that is utilized very often in the design of radiation detectors and radioisotope gauges. In this work a MC model for GM counters that is benchmarked with experiments at the primary photon energy of 59.5 keV is proposed. This is a specific purpose MC simulation code that, as opposed to publicly available general purpose MC codes, employs single scatter (or microscopic) electron transport and is currently under development. In this paper, the MC code is described in detail and the results of the specific purpose MC code are benchmarked with experiments and two general purpose MC codes, MCNP5 and PENELOPE. It was observed that the specific purpose MC code improved the reduced chi-square value when compared to MCNP5 and PENELOPE.  相似文献   
90.
An evaluation of the suitability of commercially available biopolymers on the shelf‐life of fresh salmon fillet was done. The comparison included two different types of biomaterials, poly lactic acid (PLA)‐based and starch‐based materials, and two traditional materials, amorphous polyethylene terephthalate/polyethylene (APET/PE) and high‐density polyethylene (HDPE). Fresh salmon fillets were stored at 4°C in modified atmosphere (60% CO2 and 40% N2) for 5, 7, 9 and 14 days. The biomaterials have been briefly evaluated with respect to composition and mechanical properties. The effect of different packaging materials on bacterial growth, off‐odour, pH and colour was investigated. The traditional materials (APET/PE and HDPE trays) offered the best protection regarding the bacterial growth. A relatively high level (log 6 CFU/g) of total viable counts was detected after 9 days and 14 days for fillets stored in biomaterials and traditional materials, respectively. The level of lactic acid bacteria and H2S producing bacteria followed almost the same pattern. Storage in traditional materials resulted in higher intensity of freshness (fresh odour) compared with the samples stored in biomaterials; after 14 days, the salmon stored in starch‐based pouches was regarded as having lower intensity of freshness compared with APET/PE trays and PLA‐based pouches. The opposite result was obtained regarding the colour of the salmon, where the biomaterials resulted in higher intensity of fresh colour compared with the traditional materials although the surface of the salmon at the end of the experiment was dry and unpleasant. Copyright © 2011 John Wiley & Sons, Ltd.  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