全文获取类型
收费全文 | 45203篇 |
免费 | 5568篇 |
国内免费 | 3407篇 |
专业分类
电工技术 | 5174篇 |
技术理论 | 1篇 |
综合类 | 4871篇 |
化学工业 | 3545篇 |
金属工艺 | 3233篇 |
机械仪表 | 3340篇 |
建筑科学 | 3257篇 |
矿业工程 | 1809篇 |
能源动力 | 1919篇 |
轻工业 | 1343篇 |
水利工程 | 1373篇 |
石油天然气 | 5513篇 |
武器工业 | 667篇 |
无线电 | 5757篇 |
一般工业技术 | 5751篇 |
冶金工业 | 1604篇 |
原子能技术 | 801篇 |
自动化技术 | 4220篇 |
出版年
2024年 | 227篇 |
2023年 | 708篇 |
2022年 | 1244篇 |
2021年 | 1421篇 |
2020年 | 1481篇 |
2019年 | 1263篇 |
2018年 | 1143篇 |
2017年 | 1611篇 |
2016年 | 1724篇 |
2015年 | 1830篇 |
2014年 | 2629篇 |
2013年 | 2594篇 |
2012年 | 3328篇 |
2011年 | 3552篇 |
2010年 | 2659篇 |
2009年 | 2680篇 |
2008年 | 2378篇 |
2007年 | 3051篇 |
2006年 | 2913篇 |
2005年 | 2437篇 |
2004年 | 2055篇 |
2003年 | 1873篇 |
2002年 | 1491篇 |
2001年 | 1256篇 |
2000年 | 1206篇 |
1999年 | 1010篇 |
1998年 | 778篇 |
1997年 | 696篇 |
1996年 | 600篇 |
1995年 | 494篇 |
1994年 | 438篇 |
1993年 | 292篇 |
1992年 | 234篇 |
1991年 | 185篇 |
1990年 | 175篇 |
1989年 | 169篇 |
1988年 | 106篇 |
1987年 | 48篇 |
1986年 | 35篇 |
1985年 | 22篇 |
1984年 | 29篇 |
1983年 | 12篇 |
1982年 | 16篇 |
1981年 | 11篇 |
1980年 | 12篇 |
1979年 | 9篇 |
1959年 | 10篇 |
1958年 | 4篇 |
1955年 | 7篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
921.
A comparative study of various robot motion planning schemes has been made in the present study. Two soft computing (SC)-based approaches, namely genetic-fuzzy and genetic-neural systems and a conventional potential field method (PFM) have been developed for this purpose. Training to the SC-based approaches is given off-line and the performance of the optimal motion planner has been tested on a real robot. Results of the SC-based motion planners have been compared between themselves and with those of the conventional PFM. Both the SC-based approaches are found to perform better than the PFM in terms of traveling time taken by the robot. Moreover, the performance of fuzzy logic-based motion planner is seen to be comparable with that of neural network-based motion planner. Comparisons among all these three motion planning schemes have been made in terms of robustness, adaptability, goal reaching capability and repeatability. Both the SC-based approaches are found to be more adaptive and robust compared to the PFM. It may be due to the fact that there is no in-built learning module in the PFM and consequently, it is unable to plan the velocity of the robot properly. 相似文献
922.
923.
Carmen Serrano Author Vitae Author Vitae 《Pattern recognition》2009,42(6):1052-61
In this paper a method for detecting different patterns in dermoscopic images is presented. In order to diagnose a possible skin cancer, physicians assess the lesion based on different rules. While the most famous one is the ABCD rule (asymmetry, border, colour, diameter), the new tendency in dermatology is to classify the lesion performing a pattern analysis. Due to the colour textured appearance of these patterns, this paper presents a novel method based on Markov random field (MRF) extended for colour images that classifies images representing different dermatologic patterns. First, each image plane in L*a*b* colour space is modelled as a MRF following a finite symmetric conditional model (FSCM). Coupling of colour components is taken into account by supposing that features of the MRF in the three colour planes follow a multivariate Normal distribution. Performance is analysed in different colour spaces. The best classification rate is 86% on average. 相似文献
924.
Evenly Spaced Streamlines for Surfaces: An Image-Based Approach 总被引:1,自引:0,他引:1
Benjamin Spencer Robert S. Laramee Guoning Chen Eugene Zhang 《Computer Graphics Forum》2009,28(6):1618-1631
We introduce a novel, automatic streamline seeding algorithm for vector fields defined on surfaces in 3D space. The algorithm generates evenly spaced streamlines fast, simply and efficiently for any general surface-based vector field. It is general because it handles large, complex, unstructured, adaptive resolution grids with holes and discontinuities, does not require a parametrization, and can generate both sparse and dense representations of the flow. It is efficient because streamlines are only integrated for visible portions of the surface. It is simple because the image-based approach removes the need to perform streamline tracing on a triangular mesh, a process which is complicated at best. And it is fast because it makes effective, balanced use of both the CPU and the GPU. The key to the algorithm's speed, simplicity and efficiency is its image-based seeding strategy. We demonstrate our algorithm on complex, real-world simulation data sets from computational fluid dynamics and compare it with object-space streamline visualizations. 相似文献
925.
TextonBoost for Image Understanding: Multi-Class Object Recognition and Segmentation by Jointly Modeling Texture,Layout, and Context 总被引:5,自引:0,他引:5
Jamie Shotton John Winn Carsten Rother Antonio Criminisi 《International Journal of Computer Vision》2009,81(1):2-23
This paper details a new approach for learning a discriminative model of object classes, incorporating texture, layout, and
context information efficiently. The learned model is used for automatic visual understanding and semantic segmentation of
photographs. Our discriminative model exploits texture-layout filters, novel features based on textons, which jointly model patterns of texture and their spatial layout. Unary classification
and feature selection is achieved using shared boosting to give an efficient classifier which can be applied to a large number
of classes. Accurate image segmentation is achieved by incorporating the unary classifier in a conditional random field, which
(i) captures the spatial interactions between class labels of neighboring pixels, and (ii) improves the segmentation of specific
object instances. Efficient training of the model on large datasets is achieved by exploiting both random feature selection
and piecewise training methods.
High classification and segmentation accuracy is demonstrated on four varied databases: (i) the MSRC 21-class database containing
photographs of real objects viewed under general lighting conditions, poses and viewpoints, (ii) the 7-class Corel subset
and (iii) the 7-class Sowerby database used in He et al. (Proceeding of IEEE Conference on Computer Vision and Pattern Recognition,
vol. 2, pp. 695–702, June 2004), and (iv) a set of video sequences of television shows. The proposed algorithm gives competitive and visually pleasing results
for objects that are highly textured (grass, trees, etc.), highly structured (cars, faces, bicycles, airplanes, etc.), and
even articulated (body, cow, etc.).
J. Shotton is now working at Toshiba Corporate Research & Development Center, Kawasaki, Japan. 相似文献
926.
927.
928.
929.
提出一种基于柔性衬底和三维组装方法的新型三维电场传感器.利用柔性衬底的折叠,构建一种互相垂直的新型三维电场传感器,研究了测量空间电场时的耦合,提出解耦算法,标定灵敏度矩阵,实现了空间电场三个方向分量的准确测量;通过一系列的温湿度实验研究了三维结构的形变,证明了三维电场传感器结构稳定可靠.实验结果表明:所研制的三维电场传感器不仅能消除耦合干扰,实现空间电场分量的准确测量,测量误差在3.61%以内;而且通过新的三维组装方法,大大减少了三维电场传感器的质量、体积,折叠工艺简化了三维传感器的组装,有利于批量化生产. 相似文献
930.
提出并研制了一种二维电场检测传感芯片,将四个电场测量微型单元和旋转式驱动微结构集成在3. 5 mm ×3. 5 mm的敏感结构上,实现了单芯片的电场二维测量.介绍了传感器的工作原理、敏感结构的设计,以及基于绝缘体上硅( SOI)工艺的单芯片微型二维电场传感器制备工艺技术.成功研制出传感器原理样机,研究了微型二维电场传感器的标定方法,开发了用于电场二维标定的测试装置,并在室温常压下对传感器进行了二维标定.实验结果表明:该传感器能够有效减小电场的轴间耦合干扰,测量误差优于7. 04%,线性度可达到1. 25%. 相似文献