全文获取类型
收费全文 | 54000篇 |
免费 | 3794篇 |
国内免费 | 2676篇 |
专业分类
电工技术 | 3768篇 |
综合类 | 2621篇 |
化学工业 | 3049篇 |
金属工艺 | 1725篇 |
机械仪表 | 6017篇 |
建筑科学 | 1934篇 |
矿业工程 | 1109篇 |
能源动力 | 1369篇 |
轻工业 | 1517篇 |
水利工程 | 451篇 |
石油天然气 | 3093篇 |
武器工业 | 425篇 |
无线电 | 10161篇 |
一般工业技术 | 2393篇 |
冶金工业 | 736篇 |
原子能技术 | 617篇 |
自动化技术 | 19485篇 |
出版年
2024年 | 54篇 |
2023年 | 308篇 |
2022年 | 511篇 |
2021年 | 774篇 |
2020年 | 850篇 |
2019年 | 611篇 |
2018年 | 743篇 |
2017年 | 992篇 |
2016年 | 1324篇 |
2015年 | 1576篇 |
2014年 | 2828篇 |
2013年 | 2844篇 |
2012年 | 3231篇 |
2011年 | 4190篇 |
2010年 | 3401篇 |
2009年 | 3615篇 |
2008年 | 3358篇 |
2007年 | 3972篇 |
2006年 | 3885篇 |
2005年 | 3604篇 |
2004年 | 2921篇 |
2003年 | 2721篇 |
2002年 | 2099篇 |
2001年 | 1581篇 |
2000年 | 1434篇 |
1999年 | 1377篇 |
1998年 | 1074篇 |
1997年 | 969篇 |
1996年 | 821篇 |
1995年 | 650篇 |
1994年 | 457篇 |
1993年 | 324篇 |
1992年 | 275篇 |
1991年 | 187篇 |
1990年 | 133篇 |
1989年 | 109篇 |
1988年 | 115篇 |
1987年 | 52篇 |
1986年 | 84篇 |
1985年 | 82篇 |
1984年 | 63篇 |
1983年 | 69篇 |
1982年 | 55篇 |
1981年 | 48篇 |
1980年 | 26篇 |
1979年 | 20篇 |
1978年 | 11篇 |
1977年 | 7篇 |
1976年 | 13篇 |
1973年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 476 毫秒
21.
In this paper, we propose a novel change detection method for synthetic aperture radar images based on unsupervised artificial immune systems. After generating the difference image from the multitemporal images, we take each pixel as an antigen and build an immune model to deal with the antigens. By continuously stimulating the immune model, the antigens are classified into two groups, changed and unchanged. Firstly, the proposed method incorporates the local information in order to restrain the impact of speckle noise. Secondly, the proposed method simulates the immune response process in a fuzzy way to get an accurate result by retaining more image details. We introduce a fuzzy membership of the antigen and then update the antibodies and memory cells according to the membership. Compared with the clustering algorithms we have proposed in our previous works, the new method inherits immunological properties from immune systems and is robust to speckle noise due to the use of local information as well as fuzzy strategy. Experiments on real synthetic aperture radar images show that the proposed method performs well on several kinds of difference images and engenders more robust result than the other compared methods. 相似文献
22.
Clip-art image segmentation is widely used as an essential step to solve many vision problems such as colorization and vectorization. Many of these applications not only demand accurate segmentation results, but also have little tolerance for time cost, which leads to the main challenge of this kind of segmentation. However, most existing segmentation techniques are found not sufficient for this purpose due to either their high computation cost or low accuracy. To address such issues, we propose a novel segmentation approach, ECISER, which is well-suited in this context. The basic idea of ECISER is to take advantage of the particular nature of cartoon images and connect image segmentation with aliased rasterization. Based on such relationship, a clip-art image can be quickly segmented into regions by re-rasterization of the original image and several other computationally efficient techniques developed in this paper. Experimental results show that our method achieves dramatic computational speedups over the current state-of-the-art approaches, while preserving almost the same quality of results. 相似文献
23.
Artificial bee colony (ABC) algorithm has several characteristics that make it more attractive than other bio-inspired methods. Particularly, it is simple, it uses fewer control parameters and its convergence is independent of the initial conditions. In this paper, a novel artificial bee colony based maximum power point tracking algorithm (MPPT) is proposed. The developed algorithm, does not allow only overcoming the common drawback of the conventional MPPT methods, but it gives a simple and a robust MPPT scheme. A co-simulation methodology, combining Matlab/Simulink™ and Cadence/Pspice™, is used to verify the effectiveness of the proposed method and compare its performance, under dynamic weather conditions, with that of the Particle Swarm Optimization (PSO) based MPPT algorithm. Moreover, a laboratory setup has been realized and used to experimentally validate the proposed ABC-based MPPT algorithm. Simulation and experimental results have shown the satisfactory performance of the proposed approach. 相似文献
24.
This paper summarizes the basics of pulsed thermal nondestructive testing (TNDT) including theoretical solutions, data processing algorithms and practical implementation. Typical defects are discussed along with 1D analytical and multi-dimensional numerical solutions. Special emphasis is focused on defect characterization by the use of inverse solutions. A list of TNDT terms is provided. Applications of active TNDT, mainly in the aerospace industry, are discussed briefly, and some trends in the further development of this technique are described. 相似文献
25.
从硬件和软件两个角度出发,介绍基于DSP的多元数据同步采集与存储系统的组成、工作模式以及功能的测试。系统主要由上位机和数字采集与存储单元组成,其中数字采集与存储单元的硬件部分包括电源模块,值班电路模块,数据采集模块,数据存储模块,时钟同步模块。系统采用DSP作为中央处理芯片,利用经过同步后的秒脉冲作为触发信号,实现同步数据采集。以CF卡作为存储介质,实现数据自容式存储。软件部分实现自检、同步、数据采集存储功能。经过测试,系统工作稳定,功能正常,同步精度在100ns以内。 相似文献
26.
Simulating the psychological experience of human vision,a road extraction model based on the format tower is proposed to extract the road in the high resolution remote sensing image from the perspective of morphology.Firstly,based on the spectral and texture information,the suspected road targets are extracted by using segmentation technology.Then these targets are classified according to their reliability and extract the road targets for each category.Finally,three types of identified road information are verified and merged,and the continuous smooth road extraction results are obtained.Experiments on real high resolution images show that the results are consistent with the visual perception of the human eye,and the overall classification accuracy is higher,indicating that the algorithm is effective and feasible and has good use value. 相似文献
27.
《Ceramics International》2018,44(18):22473-22480
The compact green bodies, prepared via a novel solid-liquid mixing method of precursors, were successfully pyrolyzed to obtain the dense bulk SiAlCN ceramics at 1000 °C. It can be seen from their SEM that they have uniform and dense microstructure, indicating that this method can be used to prepare bulk ceramics. In order to verify that they can be used as sensor heads, their temperature-resistance characteristics and repeatability were tested. The results show that the conductive mechanism belongs to Arrhenius's Tailed-State and Extended-State in the temperature range of 500–650 °C and 650–930 °C, respectively. And it shows that SiAlCN ceramics can be used as the sensor heads for high-temperature sensors. 相似文献
28.
Image enhancement algorithms are commonly used to increase the contrast and visual quality of low-dose x-ray images. This paper proposes an automated enhancement method using soft fuzzy sets with a new decision-making scheme based on Dempster-Shafer theory of evidence for the visual interpretation of pneumonia malformation in low-dose x-ray images, called as XEFSDS. The XEFSDS model first generates an original source x-ray image into a complementary image, then each original and complement image is applied to the characterized image object and background areas of fuzzy space. The S-function is utilized to define fuzzy soft sets for the classification of gray level ambiguity in both images, and hence a decision criterion via Dempster-Shafer approach and fuzzy interval has been adapted to discriminate uncertainties on the pixel intensity and the spatial information. Modified membership grade operations have been performed on each object/background area, and Werner’s AND/OR operator (an aggregation operator) has been utilized to build a new membership function from two modified membership functions. Finally, an enhanced image is obtained from the new membership function via defuzzification. Experiments on different pneumonia X-ray images demonstrate that the XEFSDS scheme produces better results than the existing methods. To show the advantages of the XEFSDS scheme, we have executed a segmentation based examination on enhanced image for the detection of pneumonia malformation as well as abnormal lobe (lobar pneumonia) or bronchopneumonia. 相似文献
29.
文章中主要采用有机溶剂萃取法(OSE)对高浓度石油污染土壤进行修复,经过精馏操作,有效回收原油,建立脱附等温曲线,研究了石油污染物在土壤-有机溶剂两相间的迁移规律。 相似文献
30.
实时操作系统DSP/BIOS在DSP开发中的应用 总被引:2,自引:0,他引:2
本文介绍了RTOS(实时操作系统)DSP/BIOS在DSP的开发设计中的应用。在简述了DSP的一般模型后,论述了RTOS在DSP/BIOS外设管理,实时性能分析以及程序流程控制中的应用。 相似文献