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   1000篇
  免费   21篇
  国内免费   1篇
电工技术   13篇
化学工业   177篇
金属工艺   13篇
机械仪表   20篇
建筑科学   54篇
矿业工程   22篇
能源动力   34篇
轻工业   103篇
水利工程   19篇
石油天然气   2篇
无线电   85篇
一般工业技术   124篇
冶金工业   102篇
原子能技术   2篇
自动化技术   252篇
  2023年   11篇
  2022年   21篇
  2021年   20篇
  2020年   11篇
  2019年   19篇
  2018年   17篇
  2017年   16篇
  2016年   23篇
  2015年   23篇
  2014年   23篇
  2013年   57篇
  2012年   47篇
  2011年   85篇
  2010年   55篇
  2009年   84篇
  2008年   57篇
  2007年   56篇
  2006年   50篇
  2005年   59篇
  2004年   38篇
  2003年   35篇
  2002年   25篇
  2001年   22篇
  2000年   14篇
  1999年   18篇
  1998年   13篇
  1997年   15篇
  1996年   12篇
  1995年   6篇
  1994年   6篇
  1993年   9篇
  1992年   9篇
  1991年   2篇
  1990年   8篇
  1989年   3篇
  1988年   2篇
  1987年   8篇
  1986年   2篇
  1985年   5篇
  1984年   4篇
  1983年   2篇
  1980年   2篇
  1939年   4篇
  1938年   3篇
  1932年   4篇
  1930年   1篇
  1929年   5篇
  1928年   1篇
  1927年   2篇
  1926年   3篇
排序方式: 共有1022条查询结果,搜索用时 15 毫秒
11.
Recently, Aceto, Fokkink and Ingólfsdóttir proposed an algorithm to turn any sound and ground-complete axiomatisation of any preorder listed in the linear time-branching time spectrum at least as coarse as the ready simulation preorder, into a sound and ground-complete axiomatisation of the corresponding equivalence—its kernel. Moreover, if the former axiomatisation is ω-complete, so is the latter. Subsequently, de Frutos Escrig, Gregorio Rodríguez and Palomino generalised this result, so that the algorithm is applicable to any preorder at least as coarse as the ready simulation preorder, provided it is initials preserving. The current paper shows that the same algorithm applies equally well to weak semantics: the proviso of initials preserving can be replaced by other conditions, such as weak initials preserving and satisfying the second τ-law. This makes it applicable to all 87 preorders surveyed in “the linear time-branching time spectrum II” that are at least as coarse as the ready simulation preorder. We also extend the scope of the algorithm to infinite processes, by adding recursion constants. As an application of both extensions, we provide a ground-complete axiomatisation of the CSP failures equivalence for BCCS processes with divergence.  相似文献   
12.
With the advent of the Internet, billions of images are now freely available online and constitute a dense sampling of the visual world. Using a variety of non-parametric methods, we explore this world with the aid of a large dataset of 79,302,017 images collected from the Internet. Motivated by psychophysical results showing the remarkable tolerance of the human visual system to degradations in image resolution, the images in the dataset are stored as 32 x 32 color images. Each image is loosely labeled with one of the 75,062 non-abstract nouns in English, as listed in the Wordnet lexical database. Hence the image database gives a comprehensive coverage of all object categories and scenes. The semantic information from Wordnet can be used in conjunction with nearest-neighbor methods to perform object classification over a range of semantic levels minimizing the effects of labeling noise. For certain classes that are particularly prevalent in the dataset, such as people, we are able to demonstrate a recognition performance comparable to class-specific Viola-Jones style detectors.  相似文献   
13.
When meeting someone new, the first impression is often influenced by someone’s physical appearance and other types of prejudice. In this paper, we present TouchMeDare, an interactive canvas, which aims to provide an experience when meeting new people, while preventing visual prejudice and lowering potential thresholds. The focus of the designed experience was to stimulate people to get acquainted through the interactive canvas. TouchMeDare consists of a flexible, opaque canvas, which plays music when touched simultaneously from both sides. Dynamic variation of this bodily contact is reflected through real-time adaptations of the musical compositions. Two redesigns were qualitatively and quantitatively evaluated and a final version was placed in the Lowlands Festival as a case study. Evaluation results showed that some explanation was needed for the initial interaction with the installation. On the other hand, after this initial unfamiliarity passed, results showed that making bodily contact through the installation did help people to get acquainted with each other and increased their social interaction.  相似文献   
14.
A new three-phase electrode array with a serpentine electrode is designed and prototyped using PolyMUMPs process for micro flow pumping. Numerical model of the micropump has been developed using COMSOL Multiphysics™. Experimental testing is conducted and time-averaged flow velocities from testing and simulation agree well. Peak time-averaged flow velocity of 270 μm/s is achieved at 30 Hz using ethanol.  相似文献   
15.
This paper presents a new version of fuzzy wavelet support vector classifier machine to diagnosing the nonlinear fuzzy fault system with multi-dimensional input variables. Since there exist problems of finite samples and uncertain data in complex fuzzy fault system, the input and output variables are described as fuzzy numbers. Then by integrating the fuzzy theory, wavelet analysis theory and v-support vector classifier machine, fuzzy wavelet v-support vector classifier machine (FWv-SVCM) is proposed. To seek the optimal parameters of FWv-SVCM, genetic algorithm (GA) is also applied to optimize unknown parameters of FWv-SVCM. A diagnosing method based on FWv-SVCM and GA is put forward. The results of the application in car assembly line diagnosis confirm the feasibility and the validity of the diagnosing method. Compared with the traditional model and other SVCM methods, FWv-SVCM method requires fewer samples and has better diagnosing precision.  相似文献   
16.
17.
Online bin stretching is a semi-online variant of bin packing in which the algorithm has to use the same number of bins as an optimal packing, but is allowed to slightly overpack the bins. The goal is to minimize the amount of overpacking, i.e., the maximum size packed into any bin. We give an algorithm for online bin stretching with a stretching factor of \(11/8 = 1.375\) for three bins. Additionally, we present a lower bound of \(45/33 = 1.\overline{36}\) for online bin stretching on three bins and a lower bound of 19/14 for four and five bins that were discovered using a computer search.  相似文献   
18.
A well-known problem in Petri net theory is to formalise an appropriate causality-based concept of process or run for place/transition systems. The so-called individual token interpretation, where tokens are distinguished according to their causal history, giving rise to the processes of Goltz and Reisig, is often considered too detailed. The problem of defining a fully satisfying more abstract concept of process for general place/transition systems has so-far not been solved. In this paper, we recall the proposal of defining an abstract notion of process, here called BD-process, in terms of equivalence classes of Goltz-Reisig processes, using an equivalence proposed by Best and Devillers. It yields a fully satisfying solution for at least all one-safe nets. However, for certain nets which intuitively have different conflicting behaviours, it yields only one maximal abstract process. Here we identify a class of place/transition systems, called structural conflict nets, where conflict and concurrency due to token multiplicity are clearly separated. We show that, in the case of structural conflict nets, the equivalence proposed by Best and Devillers yields a unique maximal abstract process only for conflict-free nets. Thereby BD-processes constitute a simple and fully satisfying solution in the class of structural conflict nets.  相似文献   
19.
The paper describes results of a longitudinal study of developments in the area of software product and process quality improvement within a Hungarian software company, IQSOFT Ltd. This company has been active in this area since 1993, trying to build, introduce and maintain an efficiently working quality management system which, e.g., fulfils the ISO 9001 requirements, allows steady software process improvement and, at the same time, conforms to company's own needs. Over the last eight years five phases could be distinguished. Each phase is described shortly, following the same structure, namely: basic starting points, key problem areas, literature consulted, activities and design executed, reflections on what happened and why. The lessons resulting from the analysis of this case have been formulated in terms of guidelines. We feel that these are applicable to any low maturity software development organisation embarking on a product or process quality improvement endeavour. These guidelines are developed around a framework containing the basic issues of software production (project management, technical processes and products). The guidelines advocate a careful step-by-step development of definitions, quality characteristics, and metrics related to these objects while at the same time developing and introducing the associated process.  相似文献   
20.
Normalized Difference Vegetation Index (NDVI), which is a measure of vegetation vigour, and lake water levels respond variably to precipitation and its deficiency. For a given lake catchment, NDVI may have the ability to depict localized natural variability in water levels in response to weather patterns. This information may be used to decipher natural from unnatural variations of a given lake’s surface. This study evaluates the potential of using NDVI and its associated derivatives (VCI (vegetation condition index), SVI (standardised vegetation index), AINDVI (annually integrated NDVI), green vegetation function (F g ), and NDVIA (NDVI anomaly)) to depict Lake Victoria’s water levels. Thirty years of monthly mean water levels and a portion of the Global Inventory Modelling and Mapping Studies (GIMMS) AVHRR (Advanced Very High Resolution Radiometer) NDVI datasets were used. Their aggregate data structures and temporal co-variabilities were analysed using GIS/spatial analysis tools. Locally, NDVI was found to be more sensitive to drought (i.e., responded more strongly to reduced precipitation) than to water levels. It showed a good ability to depict water levels one-month in advance, especially in moderate to low precipitation years. SVI and SWL (standardized water levels) used in association with AINDVI and AMWLA (annual mean water levels anomaly) readily identified high precipitation years, which are also when NDVI has a low ability to depict water levels. NDVI also appears to be able to highlight unnatural variations in water levels. We propose an iterative approach for the better use of NDVI, which may be useful in developing an early warning mechanisms for the management of lake Victoria and other Lakes with similar characteristics.  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