全文获取类型
收费全文 | 123180篇 |
免费 | 12648篇 |
国内免费 | 7328篇 |
学科分类
工业技术 | 143156篇 |
出版年
2024年 | 483篇 |
2023年 | 2195篇 |
2022年 | 4150篇 |
2021年 | 5779篇 |
2020年 | 4468篇 |
2019年 | 3453篇 |
2018年 | 3788篇 |
2017年 | 4215篇 |
2016年 | 3755篇 |
2015年 | 5607篇 |
2014年 | 7052篇 |
2013年 | 8316篇 |
2012年 | 9519篇 |
2011年 | 9987篇 |
2010年 | 9115篇 |
2009年 | 8453篇 |
2008年 | 8356篇 |
2007年 | 7532篇 |
2006年 | 6994篇 |
2005年 | 5536篇 |
2004年 | 3929篇 |
2003年 | 3269篇 |
2002年 | 3377篇 |
2001年 | 2916篇 |
2000年 | 2191篇 |
1999年 | 1981篇 |
1998年 | 1290篇 |
1997年 | 1076篇 |
1996年 | 1013篇 |
1995年 | 730篇 |
1994年 | 630篇 |
1993年 | 448篇 |
1992年 | 406篇 |
1991年 | 276篇 |
1990年 | 204篇 |
1989年 | 178篇 |
1988年 | 109篇 |
1987年 | 78篇 |
1986年 | 62篇 |
1985年 | 36篇 |
1984年 | 29篇 |
1983年 | 24篇 |
1982年 | 32篇 |
1981年 | 21篇 |
1980年 | 37篇 |
1979年 | 17篇 |
1977年 | 3篇 |
1970年 | 2篇 |
1959年 | 10篇 |
1951年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 19 毫秒
81.
Neural Processing Letters - The beta processes (BP) is a powerful nonparametric tool in feature learning, which is often used as the prior of Bernoulli process for choosing features from a feature... 相似文献
82.
Multifunctional 3D Patternable Drug‐Embedded Nanocarrier‐Based Interfaces to Enhance Signal Recording and Reduce Neuron Degeneration in Neural Implantation 下载免费PDF全文
83.
84.
Multimedia Tools and Applications - In Wyner-Ziv (WZ) video coding, decoder side information (SI) takes a key role in a WZ video codec among other building blocks. In this paper, we review the... 相似文献
85.
Zhen Wu Jing Yao Pengfei Zhu Fusheng Yang Xiangyu Meng Sandra Kurko Zaoxiao Zhang 《International Journal of Hydrogen Energy》2021,46(19):11183-11198
Advanced biogas power generation technology has been attracting attentions, which contributes to the waste disposal and the mitigation of greenhouse gas emissions. This work proposes and models a novel biogas-fed hybrid power generation system consisting of solid oxide fuel cell, water gas shift reaction, thermal swing adsorption and proton exchange membrane fuel cell (SOFC-WGS-TSA-PEMFC). The thermodynamic, exergetic, and thermo-economic analyses of this hybrid system for power generation were conducted to comprehensively evaluate its performance. It was found that the novel biogas-fed hybrid system has a gross energy conversion efficiency of 68.63% and exergy efficiency of 65.36%, indicating high efficiency for this kind of hybrid power technology. The market sensitivity analysis showed that the hybrid system also has a low sensitivity to market price fluctuation. Under the current subsidy level for the distributed biogas power plant, the levelized cost of energy can be lowered to 0.02942 $/kWh for a 1 MW scale system. Accordingly, the payback period and annual return on investment can reach 1.4 year and about 20%, respectively. These results reveal that the proposed hybrid system is promising and economically feasible as a distributed power plant, especially for the small power scale (no more than 2 MW). 相似文献
86.
87.
88.
89.
To improve the electrochemical properties of rare-earth–Mg–Ni-based hydrogen storage alloys, the effects of stoichiometry and Cu-substitution on the phase structure and thermodynamic properties of the ... 相似文献
90.
In the early design stage, automotive modeling should both meet the requirements of aesthetics and engineering. Therefore, a vehicle CAD (computer aided design) model that can be easily adjusted by feedbacks is necessary. Based on CE-Bézier surface, this paper presents a set of algorithms for parametric segmentation and fairing surface generation in a car model. This model is defined by a simplified automotive template and relevant control points, shape parameters and segmentation parameters, which can be modified to alter the car form efficiently. With this model and the corresponding adjustment method, more than fifty various vehicle models are established in this research according to different parameters. And two methods for calculating similarity index between car models are constructed, which are suitable for brand design trend analysis and modelling design decisionmaking. 相似文献