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   1403篇
  免费   76篇
电工技术   15篇
综合类   1篇
化学工业   456篇
金属工艺   36篇
机械仪表   27篇
建筑科学   130篇
矿业工程   6篇
能源动力   46篇
轻工业   171篇
水利工程   20篇
石油天然气   3篇
无线电   79篇
一般工业技术   185篇
冶金工业   85篇
原子能技术   15篇
自动化技术   204篇
  2023年   14篇
  2022年   43篇
  2021年   52篇
  2020年   39篇
  2019年   44篇
  2018年   58篇
  2017年   53篇
  2016年   58篇
  2015年   40篇
  2014年   65篇
  2013年   90篇
  2012年   71篇
  2011年   92篇
  2010年   69篇
  2009年   65篇
  2008年   51篇
  2007年   64篇
  2006年   44篇
  2005年   30篇
  2004年   36篇
  2003年   24篇
  2002年   22篇
  2001年   23篇
  2000年   27篇
  1999年   40篇
  1998年   29篇
  1997年   23篇
  1996年   18篇
  1995年   14篇
  1994年   16篇
  1993年   12篇
  1992年   10篇
  1991年   7篇
  1990年   8篇
  1989年   9篇
  1988年   9篇
  1987年   9篇
  1986年   5篇
  1985年   7篇
  1984年   4篇
  1983年   9篇
  1982年   6篇
  1981年   5篇
  1979年   5篇
  1978年   6篇
  1977年   4篇
  1975年   4篇
  1954年   3篇
  1940年   4篇
  1934年   3篇
排序方式: 共有1479条查询结果,搜索用时 15 毫秒
11.
For some years now, the Nederlandse Taalunie (Dutch Language Union) has been active in promoting the development of human language technology (HLT) applications for speakers of Dutch with communicative disabilities. The reason is that HLT products and services may enable them to improve their communication skills and verbal autonomy. We sought to identify a minimum common set of HLT resources that is required to develop tools for a wide range of communication disabilities. In order to reach this goal, we investigated the specific needs of communicatively disabled people and related these needs to the underlying HLT software components. By analysing the availability and quality of these essential HLT resources, we were able to identify which of the crucial elements need further research and development to become usable for developing applications for communicatively disabled speakers of Dutch. The results obtained in the current survey can be used to inform policy institutions on how they can stimulate the development of HLT resources for this target group. In the current survey results were obtained for Dutch, but a similar approach can also be applied to other languages.  相似文献   
12.
This paper describes the data used in the ChaLearn gesture challenges that took place in 2011/2012, whose results were discussed at the CVPR 2012 and ICPR 2012 conferences. The task can be described as: user-dependent, small vocabulary, fixed camera, one-shot-learning. The data include 54,000 hand and arm gestures recorded with an RGB-D \(\hbox {Kinect}^\mathrm{TM}\) camera. The data are organized into batches of 100 gestures pertaining to a small gesture vocabulary of 8–12 gestures, recorded by the same user. Short continuous sequences of 1–5 randomly selected gestures are recorded. We provide man-made annotations (temporal segmentation into individual gestures, alignment of RGB and depth images, and body part location) and a library of function to preprocess and automatically annotate data. We also provide a subset of batches in which the user’s horizontal position is randomly shifted or scaled. We report on the results of the challenge and distribute sample code to facilitate developing new solutions. The data, datacollection software and the gesture vocabularies are downloadable from http://gesture.chalearn.org. We set up a forum for researchers working on these data http://groups.google.com/group/gesturechallenge.  相似文献   
13.
Tomographic reconstruction of a binary image from few projections is considered. A novel heuristic algorithm is proposed, the central element of which is a nonlinear transformation ψ(p)=log(p/(1?p)) of the probability p that a pixel of the sought image be 1-valued. It consists of backprojections based on ψ(p) and iterative corrections. Application of this algorithm to a series of artificial test cases leads to exact binary reconstructions, (i.e., recovery of the binary image for each single pixel) from the knowledge of projection data over a few directions. Images up to 106 pixels are reconstructed in a few seconds. A series of test cases is performed for comparison with previous methods, showing a better efficiency and reduced computation times.  相似文献   
14.
With the advent of wearable sensing and mobile technologies, biosignals have seen an increasingly growing number of application areas, leading to the collection of large volumes of data. One of the difficulties in dealing with these data sets, and in the development of automated machine learning systems which use them as input, is the lack of reliable ground truth information. In this paper we present a new web-based platform for visualization, retrieval and annotation of biosignals by non-technical users, aimed at improving the process of ground truth collection for biomedical applications. Moreover, a novel extendable and scalable data representation model and persistency framework is presented. The results of the experimental evaluation with possible users has further confirmed the potential of the presented framework.  相似文献   
15.
Aqueous dispersions of anionic polyurethanes were prepared by reaction of polyethers, 1,6-hexamethylene diisocyanate, 1,2,4-benzenetricarboxylic acid anhydride and triethyl amine. Formation of the dispersion was achieved by phase reversal or by precipitation. Phase reversal occurred when the solution or the melt of the polymer was treated with water, while precipitation took place when the solution was stirred into water. The amount of acetone used has an effect on the mean particle diameter, D?T, obtained by turbidity measurements. There was an optimal acetone concentration at which D?T reached a minimum. A similar effect was observed when tetrahydrofuran, 2-butanone or acetonitrile were used as solvents instead of acetone. When the dispersion was formed by precipitation, only adequately diluted acetonic solutions formed colloidal dispersions, while concentrated solutions gave dispersions with a broad particle size distribution.  相似文献   
16.
Inspired by the relational algebra of data processing, this paper addresses the foundations of data analytical processing from a linear algebra perspective. The paper investigates, in particular, how aggregation operations such as cross tabulations and data cubes essential to quantitative analysis of data can be expressed solely in terms of matrix multiplication, transposition and the Khatri–Rao variant of the Kronecker product. The approach offers a basis for deriving an algebraic theory of data consolidation, handling the quantitative as well as qualitative sides of data science in a natural, elegant and typed way. It also shows potential for parallel analytical processing, as the parallelization theory of such matrix operations is well acknowledged.  相似文献   
17.
In the context of graph clustering, we consider the problem of simultaneously estimating both the partition of the graph nodes and the parameters of an underlying mixture of affiliation networks. In numerous applications the rapid increase of data size over time makes classical clustering algorithms too slow because of the high computational cost. In such situations online clustering algorithms are an efficient alternative to classical batch algorithms. We present an original online algorithm for graph clustering based on a Erd?s-Rényi graph mixture. The relevance of the algorithm is illustrated, using both simulated and real data sets. The real data set is a network extracted from the French political blogosphere and presents an interesting community organization.  相似文献   
18.
Hugo RJ  Jumper EJ 《Applied optics》1996,35(22):4436-4447
We discuss the use of time series of the jitter angle of multiple, small-aperture probe beams (the small-aperture beam technique, or SABT) as they emerge from a turbulent, optically active flow-field to quantify the time-varying optical path difference (OPD). The flow field studied is that for the transitionally turbulent region of a two-dimensional heated jet. Techniques to construct a complete time series of instantaneous realizations of the OPD are first applied to a numerically generated flow field and then to an experimental flow field. The SABT sensor's measurement accuracy is assessed, and its application to flow fields that differ from the numerical heated jet is discussed.  相似文献   
19.
An investigation was carried out in to thyroid hormones (TSH, T3, T4) and lipid parameters (total cholesterol, LDL cholesterol, HDL cholesterol, triglyceride) in 136 adolescents (94 femals, average age 13 years). An iodine deficiency (grade II-II) with respect to the daily urine excretion per 1,73 m2 BSA was found in 75%. With few exceptions the serum levels of TSH and T4 were in the normal range. In 36% of the patients we noticed compensatory elevated T3 levels. Correlations between thyroid hormones TSH, T4, renal iodine excretion and the volume of thyroid glands were not detectable, only T3 showed a dignificant positive correlation to the thyroid gland volume. The average values of lipids in patients were found to be higher than in normals. We consider the changed lipids as a sign of a disturbed efficacy of thyroid hormones. The regional insufficient iodine supply causes goiters and to a high degree the observed hyperchole-sterolemia, too. Our results underline the necessity of a common iodine salt prophylaxis as well as the treatment of "harmless" goiters in puberty.  相似文献   
20.
Iris recognition has been widely used in several scenarios with very satisfactory results. As it is one of the earliest stages, the image segmentation is in the basis of the process and plays a crucial role in the success of the recognition task. In this paper we analyze the relationship between the accuracy of the iris segmentation process and the error rates of three typical iris recognition methods. We selected 5000 images of the UBIRIS, CASIA and ICE databases that the used segmentation algorithm can accurately segment and artificially simulated four types of segmentation inaccuracies. The obtained results allowed us to conclude about a strong relationship between translational segmentation inaccuracies – that lead to errors in phase – and the recognition error rates.  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