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   1589篇
  免费   146篇
  国内免费   1篇
电工技术   12篇
综合类   1篇
化学工业   582篇
金属工艺   15篇
机械仪表   26篇
建筑科学   60篇
矿业工程   1篇
能源动力   42篇
轻工业   366篇
水利工程   13篇
石油天然气   7篇
无线电   90篇
一般工业技术   252篇
冶金工业   67篇
原子能技术   9篇
自动化技术   193篇
  2023年   20篇
  2022年   66篇
  2021年   217篇
  2020年   82篇
  2019年   61篇
  2018年   75篇
  2017年   54篇
  2016年   79篇
  2015年   67篇
  2014年   85篇
  2013年   111篇
  2012年   103篇
  2011年   125篇
  2010年   98篇
  2009年   75篇
  2008年   73篇
  2007年   68篇
  2006年   47篇
  2005年   47篇
  2004年   34篇
  2003年   20篇
  2002年   24篇
  2001年   14篇
  2000年   9篇
  1999年   9篇
  1998年   19篇
  1997年   12篇
  1996年   8篇
  1995年   8篇
  1994年   4篇
  1993年   4篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1989年   6篇
  1988年   1篇
  1986年   2篇
  1983年   1篇
  1982年   2篇
  1980年   1篇
  1979年   1篇
  1976年   1篇
排序方式: 共有1736条查询结果,搜索用时 296 毫秒
71.
Transport of holes in thin films of a low-bandgap alternating polyfluorene copolymer, APFO-Green5, was investigated by means of admittance spectroscopy as a function of field and temperature. The values of hole mobility were evaluated from the position of the maxima in the plots of the negative differential susceptance as a function of frequency. Hole mobility was found to be strongly field- and temperature-dependent. The charge transport parameters were extracted by analyzing the mobility data by the uncorrelated and the correlated Gaussian Disorder Models.  相似文献   
72.
It is well known that software maintenance and evolution are expensive activities, both in terms of invested time and money. Reverse engineering activities support the obtainment of abstractions and views from a target system that should help the engineers to maintain, evolve and eventually re-engineer it. Two important tasks pursued by reverse engineering are design pattern detection and software architecture reconstruction, whose main objectives are the identification of the design patterns that have been used in the implementation of a system as well as the generation of views placed at different levels of abstractions, which let the practitioners focus on the overall architecture of the system without worrying about the programming details it has been implemented with.In this context we propose an Eclipse plug-in called MARPLE (Metrics and Architecture Reconstruction Plug-in for Eclipse), which supports both the detection of design patterns and software architecture reconstruction activities through the use of basic elements and metrics that are mechanically extracted from the source code. The development of this platform is mainly based on the exploitation of the Eclipse framework and plug-ins as well as of different Java libraries for data access and graph management and visualization. In this paper we focus our attention on the design pattern detection process.  相似文献   
73.
74.
Francesca Galeazzi is an architectural engineer who leads the sustainability team at Arup Associates in Shanghai. Here she looks back with hindsight from 2050, reflecting on how rapid urbanisation in China, which started in the 1990s, played out over the next half-century. She describes how the initial highly centralised, mass urbanisation programmes gave way to a more local and community-based, participatory approach to decision-making and planning, foreshadowed by some key legislation around land ownership and design for community-based planning models in the early 2010s.  相似文献   
75.
The “Virtual Design Studio (VDS)” is a software platform currently under development in support of an integrated, coordinated and optimized design of buildings and their energy and environmental systems. It is intended to assist collaborating architects, engineers and project management team members throughout from the early phases to the detailed building design development. The platform helps to facilitate the workflow and the processing of information in combination with appropriate, task-based performance simulation tools as further analyzed in Part 2 of this study (DOI: 10.1007/s12273-013-0111-1). The present paper summarizes how VDS relates to the building design process and its typical project stages, performance-based design considerations and respective performance optimization strategies. It outlines the methodology and scope for the organization, implementation and respective requirements for the VDS platform development based on the interdisciplinary design needs. Part 2 will present the methodology for the systems integration and software implementation of VDS.  相似文献   
76.
This article explores the relationships between changes in the conception of urban peripheries and changes in urban renewal policies, mainly focusing on policy debates and theoretical discourses developed within Italy. The aim is to test the usefulness of a non‐conventional approach to urban peripheries, both from a theoretical and practical point of view. According to this approach, urban peripheries can be thought of as plural and complex places, which are considered to be a fundamental part of the city and as the builders of urban identity. The article initially explores the changes in describing and interpreting urban peripheries, showing how they must be related to actual changes in urban settlement dynamics, as well as to changes in the theoretical frameworks used to understand the phenomenon of the Italian ‘urban periphery’. The article then shows how changes in interpretation have redefined the objectives and methods of policy interventions in the Italian context. Finally, certain critical issues will be discussed, in particular the origins of urban renewal policies and their recent evolution; the redefinition of the local authority role, and the relationships between institutional and social projects and activities. In this view, institutional projects are considered to be the formal projects carried out by public actors, for example municipalities, in order to manage the change in urban peripheries while social projects are understood as the informal practices of inhabitants of peripheries that change their living neighbourhoods.  相似文献   
77.
78.
Osteoarthritis is the most common human arthritis characterized by degeneration of articular cartilage. Several studies reported that levels of human cartilage glycoprotein chitinase 3-like-1 (CHI3L1) are known as a potential marker for the activation of chondrocytes and the progression of Osteoarthritis (OA), whereas lubricin appears to be chondroprotective. The aim of this study was to investigate the co-expression and co-localization of CHI3L1 and lubricin in normal and osteoarthritic rat articular cartilage to correlate their modified expression to a specific grade of OA. Samples of normal and osteoarthritic rat articular cartilage were analyzed by the Kellgren–Lawrence OA severity scores, the Kraus’ modified Mankin score and the Histopathology Osteoarthritis Research Society International (OARSI) system for histomorphometric evaluations, and through CHI3L1 and lubricin gene expression, immunohistochemistry and double immuno-staining analysis. The immunoexpression and the mRNA levels of lubricin increased in normal cartilage and decreased in OA cartilage (normal vs. OA, p < 0.01). By contrast, the immunoexpression and the mRNA levels of CHI3L1 increased in OA cartilage and decreased in normal cartilage (normal vs. OA, p < 0.01). Our findings are consistent with reports suggesting that these two glycoproteins are functionally associated with the development of OA and in particular with grade 2/3 of OA, suggesting that in the future they could be helpful to stage the severity and progression of the disease.  相似文献   
79.
Most studies on surface-initiated controlled polymerizations for the synthesis of polymeric covalent organic-inorganic hybrid materials focus on chemical methods requiring specific modifications of the inorganic substrate. Few mechanistically-aware approaches have been undertaken towards exploiting the reactivity of defects induced by physical techniques such as ionizing radiations or UV–Vis light. Within this framework, we take grafted polymerization of styrene from γ-irradiated silica as a mechanistic testing ground where para- and diamagnetic silica defects are present, and polymerization proceeds through both radical and cationic mechanisms, resulting in a bimodal molecular weight distribution. We show that these mechanistic intricacies can be sorted out by resorting to the chemical arsenal developed in the last decades for controlled polymerizations. Specifically, we obtained a silica-polystyrene grafted material by cationic grafting from at 30 °C, a unimodal molecular weight distribution, and a relatively high molecular weight (Mn = 7.4 kDa) with a PDI of 1.68.  相似文献   
80.
The problem of see-through cancelation in digital images of double-sided documents is addressed. We show that a nonlinear convolutional data model proposed elsewhere for moderate show-through can also be effective on strong back-to-front interferences, provided that the recto and verso pure patterns are estimated jointly. To this end, we propose a restoration algorithm that does not need any classification of the pixels. The see-through PSFs are estimated off-line, and an iterative procedure is then employed for a joint estimation of the pure patterns. This simple and fast algorithm can be used on both grayscale and color images and has proved to be very effective in real-world cases. The experimental results we report in this paper demonstrate that our algorithm outperforms the ones based on linear models with no need to tune free parameters and remains computationally inexpensive despite the nonlinear model and the iterative solution adopted. Strategies to overcome some of the residual difficulties are also envisaged.  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