全文获取类型
收费全文 | 33481篇 |
免费 | 7553篇 |
国内免费 | 4820篇 |
专业分类
电工技术 | 1943篇 |
综合类 | 3902篇 |
化学工业 | 2246篇 |
金属工艺 | 904篇 |
机械仪表 | 2825篇 |
建筑科学 | 1155篇 |
矿业工程 | 616篇 |
能源动力 | 852篇 |
轻工业 | 950篇 |
水利工程 | 321篇 |
石油天然气 | 1262篇 |
武器工业 | 590篇 |
无线电 | 6183篇 |
一般工业技术 | 2657篇 |
冶金工业 | 867篇 |
原子能技术 | 780篇 |
自动化技术 | 17801篇 |
出版年
2024年 | 164篇 |
2023年 | 1070篇 |
2022年 | 1941篇 |
2021年 | 2064篇 |
2020年 | 1927篇 |
2019年 | 1508篇 |
2018年 | 1272篇 |
2017年 | 1455篇 |
2016年 | 1640篇 |
2015年 | 1778篇 |
2014年 | 2370篇 |
2013年 | 2305篇 |
2012年 | 2880篇 |
2011年 | 2905篇 |
2010年 | 2277篇 |
2009年 | 2258篇 |
2008年 | 2272篇 |
2007年 | 2442篇 |
2006年 | 2073篇 |
2005年 | 1802篇 |
2004年 | 1410篇 |
2003年 | 1195篇 |
2002年 | 968篇 |
2001年 | 755篇 |
2000年 | 620篇 |
1999年 | 525篇 |
1998年 | 424篇 |
1997年 | 305篇 |
1996年 | 264篇 |
1995年 | 182篇 |
1994年 | 151篇 |
1993年 | 106篇 |
1992年 | 86篇 |
1991年 | 78篇 |
1990年 | 88篇 |
1989年 | 51篇 |
1988年 | 28篇 |
1987年 | 26篇 |
1986年 | 36篇 |
1985年 | 25篇 |
1984年 | 17篇 |
1983年 | 17篇 |
1982年 | 28篇 |
1981年 | 19篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1959年 | 5篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
针对TLD(Tracking-Learning-Detection)算法在光照变化不均、遮挡严重、跟踪目标模糊等情况下会出现跟踪失败的问题,提出一种基于卷积神经网络优化TLD运动手势跟踪算法。选取手势特征作正样本,其背景作负样本,获取手势HOG特征并投入到卷积神经网络中加以训练,得到手势检测分类器,从而确定目标手势区域,实现手势的自动识别;再利用TLD算法对手势进行跟踪与学习,对正负样本进行估计检测并实时校正,同时运用SURF特征匹配更新跟踪器。实验结果验证,该算法对比TLD经典算法跟踪精度提高了4.24%,增强了运动手势的跟踪效果,相比经典跟踪算法拥有更高鲁棒性。 相似文献
42.
43.
Objective and quantitative assessment of skin conditions is essential for cosmeceutical studies and research on skin aging and skin regeneration. Various handcraft-based image processing methods have been proposed to evaluate skin conditions objectively, but they have unavoidable disadvantages when used to analyze skin features accurately. This study proposes a hybrid segmentation scheme consisting of Deeplab v3+ with an Inception-ResNet-v2 backbone, LightGBM, and morphological processing (MP) to overcome the shortcomings of handcraft-based approaches. First, we apply Deeplab v3+ with an Inception-ResNet-v2 backbone for pixel segmentation of skin wrinkles and cells. Then, LightGBM and MP are used to enhance the pixel segmentation quality. Finally, we determine several skin features based on the results of wrinkle and cell segmentation. Our proposed segmentation scheme achieved a mean accuracy of 0.854, mean of intersection over union of 0.749, and mean boundary F1 score of 0.852, which achieved 1.1%, 6.7%, and 14.8% improvement over the panoptic-based semantic segmentation method, respectively. 相似文献
44.
Bin Zhang Xuesong Jiang Fei Shen Xueming He Yong Fang Qiuhui Hu 《International Journal of Food Science & Technology》2021,56(6):2588-2595
This work intends to develop an online experimental system for screening of deoxynivalenol (DON) contamination in whole wheat meals by visible/near-infrared (Vis/NIR) spectroscopy and computer vision coupling technology. Spectral and image information of samples with various DON levels was collected at speed of 0.15 m s−1 on a conveyor belt. The two-type data were then integrated and subjected to chemometric analysis. Discriminant analysis showed that samples could be classified by setting 1000 μg kg−1 as the cut-off value. The best correct classified rate obtained in prediction was 93.55% based on fusion of spectral and image features, with reduced prediction uncertainty as compared to single feature. However, quantification of DON by quantitative analysis was not successful due to poor model performance. These results indicate that, although not accurate enough to provide conclusive result, this coupling technology could be adopted for rapid screening of DON contamination in cereals and feeds during processing. 相似文献
45.
Prognostic and Health Management (PHM) represents an active field of research and a major scientific challenge in many domains. It usually focuses on the failure time or the Remaining Useful Life (RUL) prediction of a system.This paper presents a generic framework, based on a discrete Bayesian Network (BN), particularly tailored for decision fusion of heterogeneous prognostic methods. The BN parameters are computed according to the fixed prognostic objectives.The effectiveness of the proposed decision fusion based methodology for the prognostic is demonstrated through the RULs estimation of turbofan engines. The application highlights the ability of the approach to estimate RULs which overpasses the performance of most other published results in the literature. 相似文献
46.
针对采用相关滤波的判别式目标跟踪遇到的瓶颈问题:由于目标快速移动引起边界效应,使得相关滤波器在学习与更新过程中可能会引入错误,最终错误的累积将导致跟踪失败。在采集深度学习特征与样本相似性度量的基础上,提出一种引入交替方向乘子方法的改进相关滤波目标跟踪算法,选择DCNN深度特征有效地表征待跟踪目标的初始状态,通过在线分类过程中样本相似性比对与半监督学习,辅助解决相关滤波器在学习过程中存在的自学习问题。所提目标跟踪算法特别适合训练样本为持续获得的、同时存储空间较小的机器学习过程,提高目标在快速运动与部分遮挡等复杂情况下的跟踪成功率,针对VOT2016标准测试视频的实验表明:当目标面临快速运动时,对比CN、SAMF、STC算法,所提DA-CFT跟踪算法将跟踪成功率分别由60.4%~73.4%、67.2%~82.9%、80.9%~88.1%提升至85.6%~91.0%。 相似文献
47.
针对时域不确定信息的融合难题,为充分体现时域信息融合的动态性特点和时间因素对融合的影响,在证据理论的基础上,提出一种考虑决策者时序偏好的时域证据融合方法。首先将决策者对时序的偏好融入时域证据融合,通过分析时域证据序列的特点,在定义时序记忆因子的基础上,对决策者的时序偏好进行度量;然后通过构建优化模型求解时序权重,再结合证据信任度的概念,对证据源进行修正;最后利用Dempster组合规则对修正后的证据进行融合。数值算例表明,与没有考虑时间因素的融合方法相比,考虑决策者时序偏好的证据融合方法可以有效处理时域信息序列中的冲突信息,得到合理的融合结果;同时,所提方法充分考虑了时域证据序列的信任度和决策者的主观偏好,可以反映决策者主观因素对时域证据融合的影响,较好地体现了时域证据融合的动态性特点。 相似文献
48.
Atsuki Yamaguchi Kazuki Fukui Yuki Fujiwara Shingo Tamaki Sachie Kusaka Fuminobu Sato 《Journal of Nuclear Science and Technology》2021,58(1):80-86
ABSTRACT It is important to perform neutron transport simulations with accurate nuclear data in the neutronics design of a fusion reactor. However, absolute values of large-angle scattering cross sections vary among nuclear data libraries even for well-examined nuclide of iron. Benchmark experiments focusing on large-angle scattering cross sections were thus performed to confirm the correctness of nuclear data libraries. The series benchmark experiments were performed at a DT neutron source facility, OKTAVIAN of Osaka University, Japan, by the unique experimental system established by the authors’ group, which can extract only the contribution of large-angle scattering reactions. This system consists of two shadow bars, target plate (iron), and neutron detector (niobium). Two types of shadow bars were used and four irradiations were conducted for one experiment, so that contribution of room-return neutrons was effectively removed and only large-angle scattering neutrons were extracted from the measured four Nb reaction rates. The obtained experimental results were compared with calculations for five nuclear data libraries including JENDL-4.0, JEFF.-3.3, FENDL-3.1, ENDF/B- VII, and recently released ENDF/B-VIII. It was found from the comparison that ENDF/B-VIII showed the best result, though ENDF/B-VII showed overestimation and others are in large underestimation at 14 MeV. 相似文献
49.
Low-light images enhancement is a challenging task because enhancing image brightness and reducing image degradation should be considered simultaneously. Although existing deep learning-based methods improve the visibility of low-light images, many of them tend to lose details or sacrifice naturalness. To address these issues, we present a multi-stage network for low-light image enhancement, which consists of three sub-networks. More specifically, inspired by the Retinex theory and the bilateral grid technique, we first design a reflectance and illumination decomposition network to decompose an image into reflectance and illumination maps efficiently. To increase the brightness while preserving edge information, we then devise an attention-guided illumination adjustment network. The reflectance and the adjusted illumination maps are fused and refined by adversarial learning to reduce image degradation and improve image naturalness. Experiments are conducted on our rebuilt SICE low-light image dataset, which consists of 1380 real paired images and a public dataset LOL, which has 500 real paired images and 1000 synthetic paired images. Experimental results show that the proposed method outperforms state-of-the-art methods quantitatively and qualitatively. 相似文献
50.
Jiangguo Xiao Wentao Zhang Teshen Wang Jiyong Zhang Haiying Du 《Ceramics International》2021,47(9):12028-12037
A series of Na5Y(MoO4)4-yAy:Dy3+ (A = WO42?, VO43?; y = 0–0.05) phosphors were synthesized by the combustion method. Some of the MoO42? sites were occupied by WO42? and VO43? anions, which enhanced the luminescence property of Dy3+-doped Na5Y(MoO4)4. XRD results show that the crystal structures of the samples were consistent with the standard Na5Y(MoO4)4 phase. Under excitation at 352 nm, the Na5Y(MoO4)4-yAy:Dy3+ phosphors exhibited a characteristic blue emission at 485 nm and a yellow emission at 577 nm, which originated from the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3+ ions, respectively. White light can be achieved by combining these blue and yellow emissions. After replacing MoO42? with WO42? and VO43? anions in Na5Y(MoO4)4:Dy3+, the luminescence intensity of Dy3+ was significantly improved due to the crystal field effect. The results indicate that Na5Y(MoO4)3.97(WO4)0.03:Dy3+ and Na5Y(MoO4)3.97(VO4)0.03:Dy3+ phosphors have good prospects for application in n-UV-excited w-LEDs. 相似文献