全文获取类型
收费全文 | 24763篇 |
免费 | 1553篇 |
国内免费 | 56篇 |
专业分类
电工技术 | 302篇 |
综合类 | 49篇 |
化学工业 | 5137篇 |
金属工艺 | 648篇 |
机械仪表 | 930篇 |
建筑科学 | 887篇 |
矿业工程 | 48篇 |
能源动力 | 917篇 |
轻工业 | 1965篇 |
水利工程 | 155篇 |
石油天然气 | 63篇 |
无线电 | 2948篇 |
一般工业技术 | 5045篇 |
冶金工业 | 2876篇 |
原子能技术 | 268篇 |
自动化技术 | 4134篇 |
出版年
2023年 | 260篇 |
2022年 | 410篇 |
2021年 | 872篇 |
2020年 | 615篇 |
2019年 | 575篇 |
2018年 | 783篇 |
2017年 | 785篇 |
2016年 | 896篇 |
2015年 | 720篇 |
2014年 | 985篇 |
2013年 | 1706篇 |
2012年 | 1577篇 |
2011年 | 1882篇 |
2010年 | 1349篇 |
2009年 | 1296篇 |
2008年 | 1313篇 |
2007年 | 1190篇 |
2006年 | 954篇 |
2005年 | 823篇 |
2004年 | 669篇 |
2003年 | 643篇 |
2002年 | 613篇 |
2001年 | 434篇 |
2000年 | 396篇 |
1999年 | 409篇 |
1998年 | 529篇 |
1997年 | 368篇 |
1996年 | 327篇 |
1995年 | 280篇 |
1994年 | 255篇 |
1993年 | 228篇 |
1992年 | 164篇 |
1991年 | 133篇 |
1990年 | 163篇 |
1989年 | 148篇 |
1988年 | 109篇 |
1987年 | 123篇 |
1986年 | 119篇 |
1985年 | 115篇 |
1984年 | 103篇 |
1983年 | 92篇 |
1982年 | 108篇 |
1981年 | 111篇 |
1980年 | 81篇 |
1979年 | 77篇 |
1978年 | 65篇 |
1977年 | 87篇 |
1976年 | 74篇 |
1975年 | 52篇 |
1974年 | 48篇 |
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
931.
Javier Solano Martínez Jérôme Mulot Fabien Harel Daniel Hissel Marie-Cécile Péra Robert I. John Michel Amiet 《Engineering Applications of Artificial Intelligence》2013,26(7):1772-1779
The aim of this paper is to present experimental validation results of an energy management system for hybrid electrical vehicles based on type-2 fuzzy logic. The energy management system (EMS) is designed by extracting knowledge from several experts using surveys. The consideration of interval type-2 fuzzy sets enables modeling the uncertainty in the answers of the experts. The validation of the EMS is performed on a real-scale heavy duty vehicle equipped with different energy sources such as batteries, fuel cell system and ultracapacitors. Experimental results are strong evidence that type-2 fuzzy logic is wide adapted for performing the energy management in hybrid electrical vehicles. 相似文献
932.
933.
Jeongseok Oh Seokswoo Cho Bumsik Ham 《Journal of Mechanical Science and Technology》2017,31(12):5761-5767
In a polyethylene boat, a transom pod is subjected to repeated thrust forces generated by an outboard motor. The structural design of the transom pod for the outboard motor must be considered because it is subjected to cyclic bending moments causing thrust forces of the outboard motor. We designed a transom pod reinforced with aluminum alloy plate inside the transom pod in a polyethylene boat and obtained an optimal thickness of the Al alloy plate to ensure the transom pod durability. We then performed a structural analysis for the transom pod reinforced with Al alloy plate and estimated the fatigue life using modified Goodman diagram. The optimal thickness of Al alloy plate was 7 mm. 相似文献
934.
935.
Continuous hydrogen production using upflow anaerobic sludge blanket reactors: effect of organic loading rate on microbial dynamics and H2 metabolism
下载免费PDF全文
![点击此处可从《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
936.
Wireless sensor–actuator networks offer flexibility for control design. One novel element which may arise in networks with multiple nodes is that the role of some nodes does not need to be fixed. In particular, there is no need to pre-allocate which nodes assume controller functions and which ones merely relay data. We present a flexible architecture for networked control using multiple nodes connected in series over analog erasure channels without acknowledgments. The control architecture proposed adapts to changes in network conditions, by allowing the role played by individual nodes to depend upon transmission outcomes. We adopt stochastic models for transmission outcomes and characterize the distribution of controller location and the covariance of system states. Simulation results illustrate that the proposed architecture has the potential to give better performance than limiting control calculations to be carried out at a fixed node. 相似文献
937.
Dae Chul Ha Ha Young Lee Yeo Won Son Soon Hong Yuk Youn Woong Choi Byung Kook Kwak Byung Cheol Shin Cheong-Weon Cho Sun Hang Cho 《Nanoscale research letters》2014,9(1):38
The purpose of this study was to synthesize biocompatible poly(2-hydroxyethyl aspartamide)–C16-iron oxide (PHEA-C16-iron oxide) nanoparticles and to evaluate their efficacy as a contrast agent for magnetic resonance imaging of lymph nodes. The PHEA-C16-iron oxide nanoparticles were synthesized by coprecipitation method. The core size of the PHEA-C16-iron oxide nanoparticles was about 5 to 7 nm, and the overall size of the nanoparticles was around 20, 60, and 150 nm in aqueous solution. The size of the nanoparticles was controlled by the amount of C16. The 3.0-T MRI signal intensity of a rabbit lymph node was effectively reduced after intravenous administration of PHEA-C16-iron oxide with the size of 20 nm. The in vitro and in vivo toxicity tests revealed the high biocompatibility of PHEA-C16-iron oxide nanoparticles. Therefore, PHEA-C16-iron oxide nanoparticles with 20-nm size can be potentially useful as T2-weighted MR imaging contrast agents for the detection of lymph nodes. 相似文献
938.
939.
Cinzia Stigliano Melissa D. Landis Daniel Y. Lee Paolo Decuzzi 《Small (Weinheim an der Bergstrasse, Germany)》2014,10(13):2688-2696
Hybrid PET/MRI scanners have the potential to provide fundamental molecular, cellular, and anatomic information essential for optimizing therapeutic and surgical interventions. However, their full utilization is currently limited by the lack of truly multi‐modal contrast agents capable of exploiting the strengths of each modality. Here, we report on the development of long‐circulating positron‐emitting magnetic nanoconstructs (PEM) designed to image solid tumors for combined PET/MRI. PEMs are synthesized by a modified nano‐precipitation method mixing poly(lactic‐co‐glycolic acid) (PLGA), lipids, and polyethylene glycol (PEG) chains with 5 nm iron oxide nanoparticles (USPIOs). PEM lipids are coupled with 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid (DOTA) and subsequently chelated to 64Cu. PEMs show a diameter of 140 ± 7 nm and a transversal relaxivity r2 of 265.0 ± 10.0 (mM × s)?1, with a r2/r1 ratio of 123. Using a murine xenograft model bearing human breast cancer cell line (MDA‐MB‐231), intravenously administered PEMs progressively accumulate in tumors reaching a maximum of 3.5 ± 0.25% ID/g tumor at 20 h post‐injection. Correlation of PET and MRI signals revealed non‐uniform intratumoral distribution of PEMs with focal areas of accumulation at the tumor periphery. These long‐circulating PEMs with high transversal relaxivity and tumor accumulation may allow for detailed interrogation over multiple scales in a clinically relevant setting. 相似文献
940.
Chi-Yeong Ahn Sun Young Kang Hyuck Jae Choi Ok-Hee Kim Yung-Eun Sung Yong-Hun Cho 《International Journal of Hydrogen Energy》2021,46(27):14713-14723
An ideal polymer electrolyte membrane fuel cell (PEMFC) is one that continuously generates electricity as long as hydrogen and oxygen (or air) are supplied to its anode and cathode, respectively. However, internal and/or external conditions could bring about the degradation of its electrodes, which are composed of nanoparticle catalysts. Particularly, when the hydrogen supply to the anode is disrupted, a reverse voltage is generated. This phenomenon, which seriously degrades the anode catalyst, is referred to as cell reversal. To prevent its occurrence, iridium oxide (IrO2) particles were added to the anode in the membrane-electrode assembly of the PEMFC single-cells. After 100 cell reversal cycles, the single-cell voltage profiles of the anode with Pt/C only and the anodes with Pt/C and various IrO2 contents were obtained. Additionally, the cell reversal-induced degradation phenomenon was also confirmed electrochemically and physically, and the use of anodes with various IrO2 contents was also discussed. 相似文献