全文获取类型
收费全文 | 42857篇 |
免费 | 6185篇 |
国内免费 | 3531篇 |
专业分类
电工技术 | 1270篇 |
综合类 | 3387篇 |
化学工业 | 7409篇 |
金属工艺 | 729篇 |
机械仪表 | 1707篇 |
建筑科学 | 725篇 |
矿业工程 | 1486篇 |
能源动力 | 446篇 |
轻工业 | 11423篇 |
水利工程 | 253篇 |
石油天然气 | 1177篇 |
武器工业 | 1250篇 |
无线电 | 6447篇 |
一般工业技术 | 1983篇 |
冶金工业 | 1694篇 |
原子能技术 | 831篇 |
自动化技术 | 10356篇 |
出版年
2024年 | 354篇 |
2023年 | 871篇 |
2022年 | 1572篇 |
2021年 | 1821篇 |
2020年 | 1942篇 |
2019年 | 1624篇 |
2018年 | 1553篇 |
2017年 | 1714篇 |
2016年 | 1920篇 |
2015年 | 2166篇 |
2014年 | 2779篇 |
2013年 | 3132篇 |
2012年 | 4119篇 |
2011年 | 3794篇 |
2010年 | 2725篇 |
2009年 | 2588篇 |
2008年 | 2407篇 |
2007年 | 2936篇 |
2006年 | 2421篇 |
2005年 | 1901篇 |
2004年 | 1484篇 |
2003年 | 1294篇 |
2002年 | 977篇 |
2001年 | 786篇 |
2000年 | 688篇 |
1999年 | 553篇 |
1998年 | 434篇 |
1997年 | 381篇 |
1996年 | 316篇 |
1995年 | 233篇 |
1994年 | 180篇 |
1993年 | 151篇 |
1992年 | 150篇 |
1991年 | 105篇 |
1990年 | 98篇 |
1989年 | 72篇 |
1988年 | 50篇 |
1987年 | 50篇 |
1986年 | 40篇 |
1985年 | 34篇 |
1984年 | 32篇 |
1983年 | 24篇 |
1982年 | 16篇 |
1981年 | 14篇 |
1980年 | 14篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1959年 | 11篇 |
1951年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
小波变换在手写体汉字识别中的应用 总被引:5,自引:0,他引:5
汉字识别中的结构类特征具有抗变形的优点,合适做为手写体识别过程使用,但其中笔划特征的提取非常困难。本文用小波变换这一图象分析中有力工具对汉字图象分析处理之后,再进行笔划的提取,其过程简洁、明晰。 相似文献
93.
首先介绍嵌入式系统VxWorks及其启动过程;分析了基于MPC 850最小系统的硬件和BSP的执行流程;重点研究了MPC850BSP的设计与应用程序加载,包括其硬件驱动程序的设计、应用程序加载、建立调试环境和target server的配置等;基于MPC850系统的Vxworks BSP调试平台的实现,对Vxworks上层应用软件和底层硬件驱动的并行开发有着很重要的意义。 相似文献
94.
95.
96.
网页信息提取方法中的启发式规则,是识别网页标签信息、利用网页节点分析结果、针对网页不同内容、完成信息提取的重要手段。本研究在对现有启发式规则进行研究分析的基础上,提出了几种优化的启发式规则,实现对网页标题、发布时间、来源以及正文内容等元素信息的精准提取。本研究进一步提出了运用编辑距离算法实现正文内容提取准确率的判定,并提出阙值优化方法,克服了正文提取中噪声节点多、内容识别不完全的缺陷,大大提高了提取的准确度。 相似文献
97.
智能视频监控中运动目标检测的研究 总被引:1,自引:0,他引:1
针对某武器试验中背景复杂,现有的背景差分法在背景模型的维持和更新不能用于长期和复杂的场景,以及对近地目标提取检测困难的问题,提出一种改进的背景差分法。该算法采用结合邻域信息的背景差分法和最大方差阈值法,能够在一定程度上减小背景滞后更新引起的运动目标检测误差,且使目标边缘提取更加明确,从而提高了系统的运行速度,实现复杂背景下的运动目标检测。在Visual C++6.0中用OpenCV实现了相关算法的设计,并给出了完成系统任务所需的部分关键代码,实现了运动目标和试验场景的分离与提取。仿真实验验证了该算法的有效性以及实时性。 相似文献
98.
《Displays》2021
As the demand for high-quality stereo images has grown in recent years, stereoscopic image quality assessment (SIQA) has become an important research area in modern image processing technology.In this paper, we propose a no-reference stereoscopic image quality assessment (NR-SIQA) model using heterogeneous ensemble learning ‘quality-aware’ features from luminance image, chrominance image, disparity and cyclopean images via quaternion wavelet transform (QWT). Firstly, luminance image and chrominance image are generated by CIELAB color space as monocular perception, and the novel disparity and cyclopean images are utilized to complement with monocular information. Then, a number of ‘quality-aware’ features in the quaternion wavelet domain are discovered, including entropy, texture features, energy features, energy differences features and MSCN coefficients of high frequency sub-band. Finally, a heterogeneous ensemble model via support vector regression (SVR) & extreme learning machine (ELM) & random forest (RF) is proposed to predict quality score, and bootstrap sampling and rotated feature space are used to increase the diversity of data distribution. Comparing with the state-of-the-art NR-SIQA models, experimental results on four public databases prove the accuracy and robustness of the proposed model. 相似文献
99.
The bivariate distributions are useful in simultaneous modeling of two random variables. These distributions provide a way to model models. The bivariate families of distributions are not much widely explored and in this article a new family of bivariate distributions is proposed. The new family will extend the univariate transmuted family of distributions and will be helpful in modeling complex joint phenomenon. Statistical properties of the new family of distributions are explored which include marginal and conditional distributions, conditional moments, product and ratio moments, bivariate reliability and bivariate hazard rate functions. The maximum likelihood estimation (MLE) for parameters of the family is also carried out. The proposed bivariate family of distributions is studied for the Weibull baseline distributions giving rise to bivariate transmuted Weibull (BTW) distribution. The new bivariate transmuted Weibull distribution is explored in detail. Statistical properties of the new BTW distribution are studied which include the marginal and conditional distributions, product, ratio and conditional momenst. The hazard rate function of the BTW distribution is obtained. Parameter estimation of the BTW distribution is also done. Finally, real data application of the BTW distribution is given. It is observed that the proposed BTW distribution is a suitable fit for the data used. 相似文献
100.
Defect inspection of glass bottles in the beverage industrial is of significance to prevent unexpected losses caused by the damage of bottles during manufacturing and transporting. The commonly used manual methods suffer from inefficiency, excessive space consumption, and beverage wastes after filling. To replace the manual operations in the pre-filling detection with improved efficiency and reduced costs, this paper proposes a machine learning based Acoustic Defect Detection (LearningADD) system. Moreover, to realize scalable deployment on edge and cloud computing platforms, deployment strategies especially partitioning and allocation of functionalities need to be compared and optimized under realistic constraints such as latency, complexity, and capacity of the platforms. In particular, to distinguish the defects in glass bottles efficiently, the improved Hilbert-Huang transform (HHT) is employed to extend the extracted feature sets, and then Shuffled Frog Leaping Algorithm (SFLA) based feature selection is applied to optimize the feature sets. Five deployment strategies are quantitatively compared to optimize real-time performances based on the constraints measured from a real edge and cloud environment. The LearningADD algorithms are validated by the datasets from a real-life beverage factory, and the F-measure of the system reaches 98.48 %. The proposed deployment strategies are verified by experiments on private cloud platforms, which shows that the Distributed Heavy Edge deployment outperforms other strategies, benefited from the parallel computing and edge computing, where the Defect Detection Time for one bottle is less than 2.061 s in 99 % probability. 相似文献