全文获取类型
收费全文 | 96249篇 |
免费 | 9455篇 |
国内免费 | 4879篇 |
专业分类
电工技术 | 6660篇 |
技术理论 | 10篇 |
综合类 | 7021篇 |
化学工业 | 15730篇 |
金属工艺 | 5290篇 |
机械仪表 | 5931篇 |
建筑科学 | 7270篇 |
矿业工程 | 2685篇 |
能源动力 | 2880篇 |
轻工业 | 6980篇 |
水利工程 | 1901篇 |
石油天然气 | 4922篇 |
武器工业 | 1103篇 |
无线电 | 11834篇 |
一般工业技术 | 10904篇 |
冶金工业 | 4528篇 |
原子能技术 | 1440篇 |
自动化技术 | 13494篇 |
出版年
2024年 | 410篇 |
2023年 | 1588篇 |
2022年 | 3246篇 |
2021年 | 4511篇 |
2020年 | 3357篇 |
2019年 | 2743篇 |
2018年 | 3063篇 |
2017年 | 3222篇 |
2016年 | 2900篇 |
2015年 | 4022篇 |
2014年 | 4906篇 |
2013年 | 5883篇 |
2012年 | 6408篇 |
2011年 | 6739篇 |
2010年 | 6010篇 |
2009年 | 5802篇 |
2008年 | 5686篇 |
2007年 | 5324篇 |
2006年 | 5307篇 |
2005年 | 4471篇 |
2004年 | 3190篇 |
2003年 | 2848篇 |
2002年 | 2986篇 |
2001年 | 2694篇 |
2000年 | 2253篇 |
1999年 | 2097篇 |
1998年 | 1616篇 |
1997年 | 1440篇 |
1996年 | 1218篇 |
1995年 | 951篇 |
1994年 | 758篇 |
1993年 | 626篇 |
1992年 | 507篇 |
1991年 | 369篇 |
1990年 | 263篇 |
1989年 | 254篇 |
1988年 | 203篇 |
1987年 | 122篇 |
1986年 | 114篇 |
1985年 | 87篇 |
1984年 | 50篇 |
1983年 | 38篇 |
1982年 | 49篇 |
1981年 | 43篇 |
1980年 | 34篇 |
1979年 | 25篇 |
1977年 | 16篇 |
1976年 | 19篇 |
1974年 | 13篇 |
1973年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
71.
Qiang Wang Lei Shen Tong Xue Gao Cheng Cheng Zhi Huang Hong Jin Fan Yuan Ping Feng 《Advanced functional materials》2021,31(2):2002187
The {100} facet of single-crystalline TiO2(B) is an ideal platform for inserting Li ions, but it is hard to be obtained due to its high surface energy. Here, the single-crystalline TiO2(B) nanobelts from H2Ti3O7 with nearly 70% {100} facets exposed are synthesized, which significantly enhances Li-storage capacity. The first-principle calculations demonstrate an ab in-plane 2D diffusion through the exposed {100} facets. As a consequence, the nanobelts can significantly accommodate Li ions in LiTiO2 formula with specific capacity up to 335 mAh g−1, which is in good agreement with the electrochemical characterizations. Coating with conductive and protective poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), the cut-off discharge voltage is as low as 0.5 V, leading to a capacity of 160.7 mAh g−1 after 1500 cycles with a retention rate of 66% at 1C. This work provides a practical strategy to increase the Li-ion capacity and cycle stability by tailoring the crystal orientation and nanostructures. 相似文献
72.
73.
Haibo Zhang Guohua Geng Kang Li Cheng Liu Yuqing Hou 《Journal of Modern Optics》2018,65(20):2278-2289
Cone-beam X-ray luminescence computed tomography (CB-XLCT) is an attractive hybrid imaging modality, and it has the potential of monitoring the metabolic processes of nanophosphors-based drugs in vivo. However, the XLCT imaging suffers from a severe ill-posed problem. In this work, a sparse nonconvex Lp (0?p?1) regularization was utilized for the efficient reconstruction for early detection of small tumour in CB-XLCT imaging. Specifically, we transformed the non-convex optimization problem into an iteratively reweighted scheme based on the L1 regularization. Further, an iteratively reweighted split augmented lagrangian shrinkage algorithm (IRW_SALSA-Lp) was proposed to efficiently solve the non-convex Lp (0?p?1) model. We studied eight different non-convex p-values (1/16, 1/8, 1/4, 3/8, 1/2, 5/8, 3/4, 7/8) in both 3D digital mouse experiments and in vivo experiments. The results demonstrate that the proposed non-convex methods outperform L2 and L1 regularization in accurately recovering sparse targets in CB-XLCT. And among all the non-convex p-values, our Lp(1/4?p?1/2) methods give the best performance. 相似文献
74.
The solvent-dependent polymorphism of the active pharmaceutical ingredient (API) carbamazepine is interpreted from calculations of the solid-state and API-solvent intermolecular interactions. These simulations suggested that apolar solute-solute interactions could be disrupted by apolar solvents. In contrast, the polar solute-solute interactions were found to be easily disrupted by polar and protic solvents. This is consistent with experimental observations that the crystallization of the metastable form II is more dominant in apolar solvents. The Mercury program remains the gold standard in terms of usability; however, further expansion into more complex simulation techniques could make this package of even greater use in pharmaceutical manufacturing workflows. 相似文献
75.
76.
Li Jinghang Zhao Zhigang Zhang Shaohui Su Cheng 《Journal of Mechanical Science and Technology》2021,35(10):4727-4735
Journal of Mechanical Science and Technology - A multi-robot collaborative towing system fixed on floating base for high load marine work was established in this paper, and its dynamics and... 相似文献
77.
针对在灰度图像着色领域中,传统算法信息提取率不高、着色效果不理想的问题,提出了基于密集神经网络的灰度图像着色算法,以实现改善着色效果,让人眼更好地观察图片信息的目的。利用密集神经网络的信息提取高效性,构建并训练了一个端到端的深度学习模型,对图像中的各类信息及特征进行提取。训练网络时与原图像进行对比,以逐渐减小网络输出结果的信息、分类等各类型的损失。训练完成后,只需向网络输入一张灰度图片,即可生成一张颜色饱满、鲜明逼真的彩色图片。实验结果表明,引入密集网络后,可有效改善着色过程中的漏色、细节信息损失、对比度低等问题,所提算法着色效果较基于VGG网络及U-Net、双流网络结构、残差网络(ResNet)等性能优异的先进着色算法而言取得了显著的改进。 相似文献
78.
Dujuan Li Wei Yan Ronghui Qi Li-Zhi Zhang 《International Journal of Hydrogen Energy》2021,46(14):9267-9279
PEM-based electrolytic air dehumidification is innovative in dehumidification that requires high precision and small space due to its high efficiency, compactness, and cleanness. However, the system dehumidification performance and durability are limited by using commercial Anatase-IrO2 catalysts. In this study, two types of structurally modified OER catalyst materials, ATO-IrO2 and ND-MnO2-IrO2, are developed to improve the performance of the system. System experiments showed that, compared to the commercial catalysts, the use of ATO-IrO2 and ND-MnO2-IrO2 as the anode catalyst can improve the dehumidification performance by 45% and 20%, respectively. Furthermore, in 50-h accelerated aging tests, the attenuation rates of the ATO-IrO2 and ND-MnO2-IrO2 systems are 3% and 8% respectively, which are far lower than the 35% attenuation of commercial catalyst. The results indicate that, as catalysts with a classic core-shell structure, ATO-IrO2 and ND-MnO2-IrO2 still have a significant impact on improving the performance of the electrolytic dehumidification systems. 相似文献
79.
能源给人类带来光明,能源给社会进步提供了动力,尤其是进入21世纪以来,能源的可持续发展己成为直接影响世界经济社会可持续发展的决定性因素之一。中国政府高瞻远瞩地提出到2020年要实现国民经济翻两番和建设节约型社会的目标,描绘了支撑这一发展目标的十分宏伟的能源发展战略,使人振奋,也对我国钢铁产业的发展提出了更高的要求,作为长期以来与我国 相似文献
80.
介绍了铁塔加工中角钢零件优化下料管理系统,阐明了系统的模块化结构及工作原理。建立的面向角钢加工工艺的优化下料管理系统可以将生产管理与下料优化两大功能整合为一体,使用极为方便。该系统在铁塔生产中,可节省大量材料,有效地提高了企业的经济效益。 相似文献