全文获取类型
收费全文 | 63823篇 |
免费 | 5872篇 |
国内免费 | 3284篇 |
专业分类
电工技术 | 4343篇 |
技术理论 | 4篇 |
综合类 | 4586篇 |
化学工业 | 10419篇 |
金属工艺 | 3569篇 |
机械仪表 | 4151篇 |
建筑科学 | 4798篇 |
矿业工程 | 1428篇 |
能源动力 | 1794篇 |
轻工业 | 4763篇 |
水利工程 | 1285篇 |
石油天然气 | 2941篇 |
武器工业 | 518篇 |
无线电 | 8021篇 |
一般工业技术 | 8226篇 |
冶金工业 | 2531篇 |
原子能技术 | 879篇 |
自动化技术 | 8723篇 |
出版年
2024年 | 277篇 |
2023年 | 964篇 |
2022年 | 1870篇 |
2021年 | 2572篇 |
2020年 | 1858篇 |
2019年 | 1635篇 |
2018年 | 1753篇 |
2017年 | 1983篇 |
2016年 | 1962篇 |
2015年 | 2671篇 |
2014年 | 3170篇 |
2013年 | 3886篇 |
2012年 | 4194篇 |
2011年 | 4602篇 |
2010年 | 4150篇 |
2009年 | 3763篇 |
2008年 | 3767篇 |
2007年 | 3487篇 |
2006年 | 3483篇 |
2005年 | 3005篇 |
2004年 | 2223篇 |
2003年 | 2118篇 |
2002年 | 2356篇 |
2001年 | 1982篇 |
2000年 | 1591篇 |
1999年 | 1408篇 |
1998年 | 1123篇 |
1997年 | 938篇 |
1996年 | 859篇 |
1995年 | 747篇 |
1994年 | 647篇 |
1993年 | 473篇 |
1992年 | 349篇 |
1991年 | 277篇 |
1990年 | 205篇 |
1989年 | 165篇 |
1988年 | 135篇 |
1987年 | 83篇 |
1986年 | 62篇 |
1985年 | 41篇 |
1984年 | 33篇 |
1983年 | 17篇 |
1982年 | 22篇 |
1981年 | 21篇 |
1980年 | 17篇 |
1979年 | 8篇 |
1976年 | 8篇 |
1975年 | 7篇 |
1959年 | 4篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
The information resources on the Web are diversified, the amount of which is increasing rapidly. Demands for selecting useful
information from the Internet, managing personal contents, and sharing contents under control have risen. In this study, we
propose the Ubiquitous Personal Study, a framework of personalized virtual study to support accessing, managing, organizing,
sharing and recommending information. In this paper, we focus on discussing the framework, and design and implementation issues
on how to implement it with Web 2.0 mash-up technology and Open Source Software. 相似文献
82.
禅是一种心灵体验,禅意的营造需要主人积极的情感投入。卫浴间是现代居室的重要组成部分,也是现代人放松身体的重要场所.本文试从卫浴产品的选择、空间的布局以及装饰三个方面展开讨论,对禅风的现实意义进行了反思。 相似文献
83.
HUANG Jin 《电脑编程技巧与维护》2008,(16)
AutoCAD是一种人机交互的绘图软件,本身并不具备参数化绘图功能,更不具备尺寸驱动功能,但用户可以利用其所提供的强大的二次开发语言AutoLISP、VisualLISP、VBA开发完全个性化的、性能更为优越的、具有尺寸驱动功能的参数化绘图软件。 相似文献
84.
Ding Chun Wang Meimin Zhou Zhili Huang Teng Wang Xiaoliang Li Jin 《Neural computing & applications》2023,35(11):8125-8142
Neural Computing and Applications - As a fundamental technique for mining and analysis of remote sensing (RS) big data, content-based remote sensing image retrieval (CBRSIR) has received a lot of... 相似文献
85.
Weather is a key factor affecting the control of air traffic. Accurate recognition and classification of similar weather scenes in the terminal area is helpful for rapid decision-making in air traffic flow management. Current researches mostly use traditional machine learning methods to extract features of weather scenes, and clustering algorithms to divide similar scenes. Inspired by the excellent performance of deep learning in image recognition, this paper proposes a terminal area similar weather scene classification method based on improved deep convolution embedded clustering (IDCEC), which uses the combination of the encoding layer and the decoding layer to reduce the dimensionality of the weather image, retaining useful information to the greatest extent, and then uses the combination of the pre-trained encoding layer and the clustering layer to train the clustering model of the similar scenes in the terminal area. Finally, terminal area of Guangzhou Airport is selected as the research object, the method proposed in this article is used to classify historical weather data in similar scenes, and the performance is compared with other state-of-the-art methods. The experimental results show that the proposed IDCEC method can identify similar scenes more accurately based on the spatial distribution characteristics and severity of weather; at the same time, compared with the actual flight volume in the Guangzhou terminal area, IDCEC's recognition results of similar weather scenes are consistent with the recognition of experts in the field. 相似文献
86.
Zheng Jianbing Gao Ming Lim Ee-Peng Lo David Jin Cheqing Zhou Aoying 《Knowledge and Information Systems》2022,64(7):1967-1996
Knowledge and Information Systems - Network robustness measures how well network structure is strong and healthy when it is under attack, such as vertices joining and leaving. It has been widely... 相似文献
87.
Wireless Networks - Friendly spectrum jamming is a flexible scheme to establish secure communications among heterogeneous wireless devices without the need of encryption. Previous works have... 相似文献
88.
Yuan Chenxi Li Guoyan Kamarthi Sagar Jin Xiaoning Moghaddam Mohsen 《Journal of Intelligent Manufacturing》2022,33(2):425-439
Journal of Intelligent Manufacturing - In recent years, driven by Industry 4.0 wave, academic research has focused on the science, engineering, and enabling technologies for intelligent and cyber... 相似文献
89.
吉林一号卫星测控采用USB测控体制,遥控接收采用FFT+DPLL1+DPLL2的架构,FFT主要实现对载波的粗捕,DPLL1在FFT的基础上实现对载波相位的精跟踪,DPLL2实现副载波的跟踪。对遥控副载波跟踪所用到的数字PLL技术进行了研究,首先给出了载波多普勒折算到副载波上的方法,然后对模拟PLL数字化进行了详细的论述,并设计了遥控副载波同步用的PLL2,对其稳定性、快捕带及快捕时间、捕获带和捕获时间、同步速率等进行了分析和仿真。结果表明,该方法具有捕获时间短、跟踪精度高、稳定性好等特点,易于数字化实现,已成功在吉林一号系列卫星中得到应用。 相似文献
90.
Hollow Pd/MOF Nanosphere with Double Shells as Multifunctional Catalyst for Hydrogenation Reaction 下载免费PDF全文
Mingming Wan Xinlu Zhang Meiyan Li Bo Chen Jie Yin Haichao Jin Lin Lin Chao Chen Ning Zhang 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(38)
A new type of hollow nanostructure featured double metal‐organic frameworks shells with metal nanoparticles (MNPs) is designed and fabricated by the methods of ship in a bottle and bottle around the ship. The nanostructure material, hereinafter denoted as Void@HKUST‐1/Pd@ZIF‐8, is confirmed by the analyses of photograph, transmission electron microscopy, scanning electron microscopy, powder X‐ray diffraction, inductively coupled plasma, and N2 sorption. It possesses various multifunctionally structural characteristics such as hollow cavity which can improve mass transfer, the adjacent of the inner HKUST‐1 shell to the void which enables the matrix of the shell to host and well disperse MNPs, and an outer ZIF‐8 shell which acts as protective layer against the leaching of MNPs and a sieve to guarantee molecular‐size selectivity. This makes the material eligible candidates for the heterogeneous catalyst. As a proof of concept, the liquid‐phase hydrogenation of olefins with different molecular sizes as a model reaction is employed. It demonstrates the efficient catalytic activity and size‐selectivity of Void@HKUST‐1/Pd@ZIF‐8. 相似文献