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   1395篇
  免费   73篇
电工技术   21篇
综合类   2篇
化学工业   362篇
金属工艺   43篇
机械仪表   32篇
建筑科学   77篇
矿业工程   3篇
能源动力   49篇
轻工业   79篇
水利工程   11篇
石油天然气   5篇
无线电   86篇
一般工业技术   268篇
冶金工业   89篇
原子能技术   5篇
自动化技术   336篇
  2023年   17篇
  2022年   31篇
  2021年   63篇
  2020年   36篇
  2019年   32篇
  2018年   44篇
  2017年   45篇
  2016年   54篇
  2015年   63篇
  2014年   56篇
  2013年   96篇
  2012年   80篇
  2011年   116篇
  2010年   78篇
  2009年   72篇
  2008年   92篇
  2007年   75篇
  2006年   65篇
  2005年   43篇
  2004年   32篇
  2003年   22篇
  2002年   24篇
  2001年   17篇
  2000年   18篇
  1999年   32篇
  1998年   20篇
  1997年   14篇
  1996年   6篇
  1995年   13篇
  1994年   15篇
  1993年   5篇
  1990年   8篇
  1989年   3篇
  1988年   4篇
  1986年   4篇
  1985年   5篇
  1984年   4篇
  1983年   8篇
  1982年   6篇
  1981年   5篇
  1979年   3篇
  1978年   5篇
  1977年   4篇
  1976年   3篇
  1974年   3篇
  1973年   2篇
  1972年   2篇
  1968年   2篇
  1966年   2篇
  1958年   3篇
排序方式: 共有1468条查询结果,搜索用时 15 毫秒
991.
992.
993.
Adiox™ is an innovative material for removing toxic dioxins from combustion gases, making it an ideal absorbing material for tower packings and demisters in wet scrubbers. Adiox can also be used as a police filter to reduce the memory effect, as well as the primary dioxin removal technology. Sven Andersson, Siegfried Kreisz and Hans Hunsinger discuss this novel technology for the cleaning of flue gases.  相似文献   
994.
The regeneration of the posterior portion of the body after fission was studied in the holothurian Cladolabes schmeltzii using electron microscopy methods. Following fission, the aquapharyngeal complex, gonad and anterior portion of the first descending part of the intestine remain in the anterior fragment of the body. The entire regeneration process is divided into five stages. In the first three stages, the digestive system and damaged ends of the longitudinal muscle bands regenerate. The intestine is formed through the rearrangement and growth of the remaining portion of the first descending part of the intestine. The gut anlage grows down the mesentery and joins the regenerating cloaca. The cloaca is formed from two sources: its posterior portion appears as a result of immersion of the epidermis, while the anterior portion develops from the terminal segment of the growing intestine. Regeneration of muscles progresses in the typical manner for echinoderms: through immersion and myogenic transformation of the coelomic epithelium. Respiratory trees appear in animals when the growth of the external part of the body has begun (fourth stage). They are formed as an outgrowth of the dorsal wall of the anterior portion of the cloaca. It was concluded that regeneration of the posterior portion of the body in the holothurian C. schmeltzii following fission is realized through morphallactic rearrangements of the remaining parts of organs. The main mechanism through which the digestive, respiratory, and contractile systems are formed is epithelial morphogenesis. Microsc. Res. Tech. 78:540–552, 2015. © 2015 Wiley Periodicals, Inc.  相似文献   
995.
Parameterisation of kinetic models plays a central role in computational systems biology. Besides the lack of experimental data of high enough quality, some of the biggest challenges here are identification issues. Model parameters can be structurally non‐identifiable because of functional relationships. Noise in measured data is usually considered to be a nuisance for parameter estimation. However, it turns out that intrinsic fluctuations in particle numbers can make parameters identifiable that were previously non‐identifiable. The authors present a method to identify model parameters that are structurally non‐identifiable in a deterministic framework. The method takes time course recordings of biochemical systems in steady state or transient state as input. Often a functional relationship between parameters presents itself by a one‐dimensional manifold in parameter space containing parameter sets of optimal goodness. Although the system''s behaviour cannot be distinguished on this manifold in a deterministic framework it might be distinguishable in a stochastic modelling framework. Their method exploits this by using an objective function that includes a measure for fluctuations in particle numbers. They show on three example models, immigration‐death, gene expression and Epo‐EpoReceptor interaction, that this resolves the non‐identifiability even in the case of measurement noise with known amplitude. The method is applied to partially observed recordings of biochemical systems with measurement noise. It is simple to implement and it is usually very fast to compute. This optimisation can be realised in a classical or Bayesian fashion.Inspec keywords: biochemistry, physiological models, stochastic processes, measurement errors, fluctuations, parameter estimationOther keywords: model parameter identification, deterministic framework, biochemical system, steady state, transient state, stochastic modelling framework, objective function, immigration‐death model, gene expression, Epo–EpoReceptor interaction, stochastic fluctuations, measurement noise  相似文献   
996.
Crude oil is becoming scarcer and more expensive, resulting in alternative biobased or partially biobased materials gaining importance in the field of plastic packaging and encouraging the development of naturally derived, protein‐based plastics (Endres, 2009; Jones and McClements, Compreh. Rev. Food Sci. Food Safety 2010, 9, 374; Khwaldia et al., Compreh. Rev. Food Sci. Food Safety 2010, 9, 374). A strategy to improve extrusion processing behavior of proteins is the blending with other polymers. In this study ethylene vinyl acetate (EVA) was used for such purpose. The aim of this study was to determine the properties of blends of thermoplastic whey protein (TPP) and ethylene vinyl acetate (EVA). Mechanical and barrier properties were tested. Blends of differing TPP/EVA ratio were produced and extruded into flat films. Morphological analysis of the blends shows immiscibility of the TPP and EVA, greatly influencing the mechanical properties. Young's modulus measurements shows the values approached that of pure EVA with increasing EVA ratios. At values of about 21 MPa, corresponding to EVA ratios of 30% (w/w) and above, continuous extrusion including material take‐off was possible. At higher whey protein ratios in the blends the water vapor transmission rate increased, i.e., the higher water vapor transmission rate of whey protein compared with EVA dominated this property. This study showed that whey proteins can be utilized for extrusion by blending with EVA. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41172.  相似文献   
997.
998.
Injection and extraction of charges through ohmic contacts are required for efficient operation of semiconductor devices. Treatment using polar non‐solvents switches polar anode surfaces, including PEDOT:PSS and ITO, from barrier‐limited hole injection and extraction to ohmic behaviour. This is caused by an in‐situ modification of the anode surface that is buried under a layer of organic semiconductor. The exposure to methanol removes polar hydroxyl groups from the buried anode interface, and permanently increases the work function by 0.2–0.3 eV. In the case of ITO/PEDOT:PSS/PBDTTT‐CT:PC71BM/Al photovoltaic devices, the higher work function promotes charge transfer, leading to p‐doping of the organic semiconductor at the interface. This results in a two‐fold increase in hole extraction rates which raises both the fill factor and the open‐circuit voltage, leading to high power conversion efficiency of 7.4%. In ITO/PEDOT:PSS/F8BT/Al polymer light‐emitting diodes, where the organic semiconductor's HOMO level lies deeper than the anode Fermi level, the increased work function enhances hole injection efficiency and luminance intensity by 3 orders of magnitude. In particular, hole injection rates from PEDOT:PSS anodes are equivalent to those achievable using MoO3. These findings exemplify the importance of work function control as a tool for improved electrode design, and open new routes to device interfacial optimization using facile solvent processing techniques. Such simple, persistent, treatments pave the way towards low cost manufacturing of efficient organic optoelectronic devices.  相似文献   
999.
In city planning managing, the third dimension is becoming a necessity. Using 3D GIS modeling offers a flexible interactive system while providing one of the best visual interpretation of data which supports planning and decision processes for city planners. As a result, 3D GIS model expresses terrain features in an intuitive way which enhances the management and analysis of a proposed project through 3D visualization. This paper discusses the concept of 3D GIS modeling techniques using a simple procedure to generate a university campus model (real 3D GIS model) which will show the effectiveness of this approach. The 3D GIS model provides access to mapping data to support planning, design and data management. Intelligent GIS models and GIS tools help community planning and apply regional and discipline-specific standards. Integration of GIS spatial data with campus organization helps to improve quality, productivity and asset management. The following study built 3D GIS map and all utility information for AI al-Bayt University campus as an example. The primary objective is to improve data management (e.g., maps, plans, usage of facilities and services) and to develop methods using 3D spatial analysis for specific applications at the university.  相似文献   
1000.
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