全文获取类型
收费全文 | 157552篇 |
免费 | 14159篇 |
国内免费 | 8323篇 |
专业分类
电工技术 | 10258篇 |
技术理论 | 15篇 |
综合类 | 11690篇 |
化学工业 | 25347篇 |
金属工艺 | 8561篇 |
机械仪表 | 10093篇 |
建筑科学 | 13102篇 |
矿业工程 | 4326篇 |
能源动力 | 4617篇 |
轻工业 | 11979篇 |
水利工程 | 3073篇 |
石油天然气 | 8202篇 |
武器工业 | 1689篇 |
无线电 | 18582篇 |
一般工业技术 | 18000篇 |
冶金工业 | 6852篇 |
原子能技术 | 1987篇 |
自动化技术 | 21661篇 |
出版年
2024年 | 651篇 |
2023年 | 2368篇 |
2022年 | 4258篇 |
2021年 | 5933篇 |
2020年 | 4606篇 |
2019年 | 3864篇 |
2018年 | 4302篇 |
2017年 | 4930篇 |
2016年 | 4456篇 |
2015年 | 6333篇 |
2014年 | 7865篇 |
2013年 | 9501篇 |
2012年 | 10594篇 |
2011年 | 11373篇 |
2010年 | 10305篇 |
2009年 | 9946篇 |
2008年 | 9807篇 |
2007年 | 9373篇 |
2006年 | 9225篇 |
2005年 | 7821篇 |
2004年 | 5616篇 |
2003年 | 4780篇 |
2002年 | 4755篇 |
2001年 | 4213篇 |
2000年 | 3706篇 |
1999年 | 3627篇 |
1998年 | 2938篇 |
1997年 | 2413篇 |
1996年 | 2256篇 |
1995年 | 1780篇 |
1994年 | 1542篇 |
1993年 | 1139篇 |
1992年 | 904篇 |
1991年 | 678篇 |
1990年 | 517篇 |
1989年 | 421篇 |
1988年 | 367篇 |
1987年 | 215篇 |
1986年 | 190篇 |
1985年 | 125篇 |
1984年 | 65篇 |
1983年 | 58篇 |
1982年 | 66篇 |
1981年 | 46篇 |
1980年 | 38篇 |
1979年 | 17篇 |
1976年 | 11篇 |
1973年 | 6篇 |
1959年 | 7篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
This paper is concerned with the problem of joint input and state estimation for linear stochastic systems with direct feedthrough. Based on the fact that each unknown input between any two time steps is always bounded, a novel improved algorithm is proposed. Compared with existing results, this algorithm can effectively enhance estimation accuracy. Moreover, the stability of the algorithm is also discussed. Finally, an illustrative example is given to demonstrate the effectiveness of the proposed approach. 相似文献
73.
74.
Mingchang Lin Yufei Zhang Guosong Chen Ming Jiang 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(45):6065-6070
Glyco‐mimicking nanoparticles (glyco‐NPs) with Förster resonance energy transfer (FRET) donor and acceptor groups formed via dynamic covalent bond of benzoboroxole and sugar from two complementary polymers are prepared. The glyco‐NPs are proved to be quite stable under physiological conditions but sensitive to pH. So the glyco‐NPs can be internalized by dendritic cells with integrity and nontoxicity and then dissociate within the acidic organelles. This particle dissociation is directly observed and visualized in vitro, for the first time via the FRET measurements and fluorescent microscopy. This feature makes controlled release of drug or protein by glyco‐NPs possible, i.e., when model antigen Ovalbumin is loaded in the glyco‐NPs, the released Ovalbumin in dendritic cells stimulates T cells more efficiently than the free Ovalbumin itself as a result of the enhanced antigen processing and presentation. Thus, the results enlighten a bright future of the glyco‐NPs in immunotherapy. 相似文献
75.
The Journal of Supercomputing - Cyber physical system (CPS) is consisting of two interdependent networks, i.e., a cyber network embedding into a physical network. Although interdependence makes the... 相似文献
76.
“Smart firefighting” construction as a part of the “smart city” has been a concern of the public security and fire agencies at all levels. In this study, the status, problems, and reflections of “smart firefighting” construction in China are discussed. A recent survey indicates that China has launched its smart firefighting construction and initially created a new perspective on its regional smart firefighting work based on three main aspects: intelligent disaster perception by Internet of Things (IoT) construction, intelligent disaster prevention by big data construction, and intelligent disaster disposal by emergency rescue platform construction. However, the current smart firefighting construction in China still has some prominent problems such as the data interconnectivity and normalized management of various platforms, the extensibility of smart firefighting platforms, and the intelligent level of smart firefighting researches, which need to be solved urgently. Therefore, we argue that smart firefighting construction in China should establish data interconnectivity, industrial normalized management, 2D/3D geographic information interaction and extension, high-integration fire protection theory, and many other aspects in the near future and truly realize firefighting visualization and efficient data applications for 4D time space. This study could provide valuable reference for smart firefighting and smart city construction. 相似文献
77.
78.
79.
Yong Pan Chen Zhu Wen Bin Zeng Pei Fu Chi Chen Bao Ming Xu Zhong Feng Gao 《Chembiochem : a European journal of chemical biology》2021,22(24):3431-3436
Rapid and sensitive point-of-care testing (POCT) is an extremely critical mission in practical applications, especially for rigorous military medicine, home health care, and in the third world. Here, we report a visual POCT method for adenosine triphosphate (ATP) detection based on Taylor rising in the corner of quadratic geometries between two rod surfaces. We discuss the principle of Taylor rising, demonstrating that it is significantly influenced by contact angle, surface tension, and density of the sample, which are controlled by ATP-dependent rolling circle amplification (RCA). In the presence of ATP, RCA reaction effectively suppresses Taylor-rising behavior, due to the increased contact angle, density, and decreased surface tension. Without addition of ATP, untriggered RCA reaction is favorable for Taylor rising, resulting in a significant height. With this proposed method, visual sensitive detection of ATP without the aid of other instruments is realized with only a 5 μL droplet, which has good selectivity and a low detection limit (17 nM). Importantly, this visual method provides a promising POCT tool for user-friendly molecular diagnostics. 相似文献
80.
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