全文获取类型
收费全文 | 42277篇 |
免费 | 9320篇 |
国内免费 | 6312篇 |
专业分类
电工技术 | 1758篇 |
技术理论 | 2篇 |
综合类 | 5398篇 |
化学工业 | 1000篇 |
金属工艺 | 762篇 |
机械仪表 | 3593篇 |
建筑科学 | 1457篇 |
矿业工程 | 568篇 |
能源动力 | 315篇 |
轻工业 | 1050篇 |
水利工程 | 439篇 |
石油天然气 | 499篇 |
武器工业 | 528篇 |
无线电 | 10749篇 |
一般工业技术 | 3596篇 |
冶金工业 | 635篇 |
原子能技术 | 230篇 |
自动化技术 | 25330篇 |
出版年
2024年 | 166篇 |
2023年 | 847篇 |
2022年 | 1476篇 |
2021年 | 1837篇 |
2020年 | 1741篇 |
2019年 | 1420篇 |
2018年 | 1300篇 |
2017年 | 1683篇 |
2016年 | 1824篇 |
2015年 | 2234篇 |
2014年 | 3006篇 |
2013年 | 2875篇 |
2012年 | 3748篇 |
2011年 | 3875篇 |
2010年 | 3368篇 |
2009年 | 3334篇 |
2008年 | 3527篇 |
2007年 | 3644篇 |
2006年 | 2965篇 |
2005年 | 2615篇 |
2004年 | 2109篇 |
2003年 | 1666篇 |
2002年 | 1286篇 |
2001年 | 1043篇 |
2000年 | 788篇 |
1999年 | 597篇 |
1998年 | 486篇 |
1997年 | 434篇 |
1996年 | 344篇 |
1995年 | 284篇 |
1994年 | 235篇 |
1993年 | 202篇 |
1992年 | 161篇 |
1991年 | 122篇 |
1990年 | 119篇 |
1989年 | 85篇 |
1988年 | 70篇 |
1987年 | 49篇 |
1986年 | 53篇 |
1985年 | 52篇 |
1984年 | 41篇 |
1983年 | 49篇 |
1982年 | 32篇 |
1981年 | 25篇 |
1980年 | 12篇 |
1979年 | 13篇 |
1976年 | 8篇 |
1975年 | 8篇 |
1973年 | 6篇 |
1959年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
81.
The advancement of science and technology has a positive effect on the development of law disciplines. The development of algorithms and artificial intelligence also has a certain impact on judicial practice. Image restoration is a significant technique in image processing. It aims to objectively restore the content or quality of the original image from the degraded image. Image degradation is always generated in image transmission, such as distortion, blur. In modern video surveillance system, image restoration is significant for criminal investigation. However, image restoration based on conventional filter algorithms cannot achieve satisfactory performance. Thus, we first introduce the image restoration algorithms based on different degradation model. Then, we propose some applications of fuzzy image restoration in criminal investigation. We conduct experiments on both degraded images and videos and experimental results have shown the effectiveness of fuzzy image restoration applying to the criminal investigation. 相似文献
82.
Alap Ali ZAHID Syed Raza ur REHMAN S. RUSHD Anwarul HASAN Mohammad Azizur RAHMAN 《Frontiers in Energy》2020,14(3):635
Imaging with high definition video camera is an important technique to visualize the drilling conditions and to study the physics of complex multiphase flow associated with the hole cleaning process. The main advantage of visualizing multiphase flow in a drilling annulus is that the viewer can easily distinguish fluid phases, flow patterns and thicknesses of cutting beds. In this paper the hole cleaning process which involves the transportation of cuttings through a horizontal annulus was studied. The two-phase (solid-liquid) and the three-phase (solid-liquid-gas) flow conditions involved in this kind of annular transportation were experimentally simulated and images were taken using a high definition camera. Analyzing the captured images, a number of important parameters like velocities of different phases, heights of solid beds and sizes of gas bubbles were determined. Two different techniques based on an image analysis software and MATLAB coding were used for the determinations. The results were compared to validate the image analyzing methodology. The visualization technique developed in this paper has a direct application in investigating the critical conditions required for efficient hole cleaning as well as in optimizing the mud program during both planning and operational phases of drilling. Particularly, it would be useful in predicting the cuttings transport performance, estimating solid bed height, gas bubble size, and mean velocities of bubbles/particles. 相似文献
83.
基于Matlab软件开发了自动识别气液两相流界面程序,程序可获得气液界面变化、汽膜厚度、汽膜脱离周期和汽膜法向速度等特征。利用该程序对沟槽结构加热表面朝下布置时,在不同倾角、不同热流密度下的汽泡动态数据进行了处理和分析。结果表明:加热表面朝下发生核态沸腾时,汽膜厚度随热流密度的增大而增大,汽泡脱离周期随热流密度的增大先减小,而后维持在一稳定值;汽膜脱离周期随倾角的增大而减小,倾角为5°时的汽膜脱离周期稳定在0.27 s左右。当发生沸腾危机时,汽膜厚度迅速减小,这可作为动态监测加热表面沸腾状态的依据。 相似文献
84.
85.
86.
Bikash Meher Sanjay Agrawal Rutuparna Panda Lingraj Dora Ajith Abraham 《International journal of imaging systems and technology》2020,30(3):558-576
Recently, the sparse representation (SR) based algorithms have gained much attention from the researchers in the area of image fusion (IF). The building of a compact discriminative dictionary plays a vital role in the sparse-based IF techniques. In this context, an efficient multimodal IF method based on improved dictionary learning is investigated. The key contributions of this paper are: (a) An improved KSVD algorithm is suggested for the dictionary learning process, (b) to reduce the computational time, only the informative patches are selected using energy feature, and (c) a novel region-based fusion scheme is suggested for the first time for the problem on hand. The suggested technique is tested with a number of multimodal images from Harvard Medical School brain database. The results are compared with state-of-the-art multiscale transform-based methods and modified SR-based methods. Unlike earlier methods, our proposed technique generates an adaptive dictionary through selection of informative patches only. This results in a compact dictionary with improved computational efficiency. The experimental results reveal that our approach outperforms other methods. The potential application of the suggested method could be in pathological images for follow-up study and better treatment planning. 相似文献
87.
两种多层穿梭车系统的性能比较分析 总被引:1,自引:0,他引:1
物流配送中心订单响应速度的加快,对订单拣选系统提出了更高的要求。多层穿梭车系统因其柔性强、效率高等特点,近年来得到了广泛应用。多层穿梭车系统具有两种形式--基于转载车和基于环形输送线,二者均可实现货物的快速拣选,但在系统吞吐量和订单完成周期方面存在差异,致使企业决策者难以进行系统选择。基于上述原因,本文比较两种多层穿梭车系统的性能差异。建立两个系统的开环排队网络模型,然后求解系统吞吐量、订单完成周期,通过仿真验证了排队论模型的准确性,通过试验对两种系统的性能进行对比分析。结果表明,系统吞吐量与层数、巷道数相关,层数越多,巷道数越少,转载车系统相对于环线系统优势越显著;订单完成周期与层数、订单到达率相关,层数越多,订单到达率越低,转载车系统相对于环线系统越具优势。 相似文献
88.
89.
《Displays》2021
Recently, the proposal of graph convolutional networks (GCN) has successfully implemented into hyperspectral image data representation and analysis. In spite of the great success, there are still several major challenges in hyperspectral image classification, including within-class diversity, and between-class similarity, which generally degenerate hyperspectral image classification performance. To address the problems, we propose a discriminative graph convolution networks (DGCN) for hyperspectral image classification. This method introduces the concepts of within-class scatter and between-class scatter, which respectively reflect the global geometric structure and discriminative information of the input space. The experimental results on the hyperspectral data sets show that the proposed method has good classification performance. 相似文献
90.
In this paper, a new inverse identification method of constitutive parameters is developed from full kinematic and thermal field measurements. It consists in reconstructing the heat source field from two different approaches by using the heat diffusion equation. The first one requires the temperature field measurement and the value of the thermophysical parameters. The second one is based on the kinematic field measurement and the choice of a thermo-hyperelastic model that contains the parameters to be identified. The identification is carried out at the local scale, ie, at any point of the heat source field, without using the boundary conditions. In the present work, the method is applied to the challenging case of hyperelasticity from a heterogeneous test. Due to large deformations undergone by the rubber specimen tested, a motion compensation technique is developed to plot the kinematic and the thermal fields at the same points before reconstructing the heterogeneous heat source field. In the present case, the constitutive parameter of the Neo-Hookean model has been identified, and its distribution has been characterized with respect to the strain state at the surface of a cross-shaped specimen. 相似文献