全文获取类型
收费全文 | 2467篇 |
免费 | 180篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 21篇 |
综合类 | 2篇 |
化学工业 | 625篇 |
金属工艺 | 125篇 |
机械仪表 | 171篇 |
建筑科学 | 40篇 |
能源动力 | 141篇 |
轻工业 | 208篇 |
水利工程 | 21篇 |
石油天然气 | 5篇 |
武器工业 | 2篇 |
无线电 | 351篇 |
一般工业技术 | 489篇 |
冶金工业 | 113篇 |
原子能技术 | 55篇 |
自动化技术 | 283篇 |
出版年
2024年 | 3篇 |
2023年 | 33篇 |
2022年 | 62篇 |
2021年 | 99篇 |
2020年 | 61篇 |
2019年 | 63篇 |
2018年 | 83篇 |
2017年 | 82篇 |
2016年 | 84篇 |
2015年 | 78篇 |
2014年 | 119篇 |
2013年 | 166篇 |
2012年 | 221篇 |
2011年 | 254篇 |
2010年 | 162篇 |
2009年 | 182篇 |
2008年 | 128篇 |
2007年 | 87篇 |
2006年 | 96篇 |
2005年 | 87篇 |
2004年 | 72篇 |
2003年 | 58篇 |
2002年 | 49篇 |
2001年 | 54篇 |
2000年 | 53篇 |
1999年 | 42篇 |
1998年 | 67篇 |
1997年 | 26篇 |
1996年 | 14篇 |
1995年 | 12篇 |
1994年 | 15篇 |
1993年 | 11篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有2652条查询结果,搜索用时 15 毫秒
91.
Chun Tae Yoon Park Jin Bae Choi Yoon Ho 《International Journal of Control, Automation and Systems》2018,16(1):377-386
International Journal of Control, Automation and Systems - In this paper, we propose a novel Q-learning method based on multirate generalized policy iteration (MGPI) for unknown discrete-time (DT)... 相似文献
92.
93.
We consider the economic lot scheduling problem with returns by assuming that each item is returned by a constant rate of demand. The goal is to find production frequencies, production sequences, production times, as well as idle times for several items subject to returns at a single facility. We propose a heu ristic algorithm based on a time-varying (TV) lot sizes approach. The problem is decomposed into two distinct portions: in the first, we find a combinatorial part (production frequencies and sequences) and in the second, we determine a continuous part (production and idle times) in a specific production sequence. We report computational results that show that, in many cases, the proposed TV lot sizes approach with consideration of returns yields a relatively minor error. 相似文献
94.
A statically recrystallized Mg-3Al-1Zn alloy was fabricated by low temperature roll heating (140 °C) processes and subsequent
annealing at 250 °C for 5 min. The fabricated sheet, with a grain size of 4.1 m, shows an improved planar anisotropy and higher
elongations to failure at room temperature and 200 °C, compared with those of the sheet fabricated by conventional hot rolling
processes, due to the weak basal texture along with the refined microstructure. 相似文献
95.
Kwan-Ho Kim Su-Dong Park Jae-Hwan Kim Chul-Min Bae 《Metals and Materials International》2012,18(6):917-921
The fatigue characteristics of bearing steel in ultrasonic fatigue tests are investigated with regard to the role of spheroidized carbides. The results show that, despite a similar hardness level, the bearing steel with spheroidized carbide has a much longer fatigue life than steel without, and that the failure mechanism differs in each case. All the samples of SAQT-processed steel examined using ultrasonic fatigue tests were characterized by a conventional fish-eye structure, which implies they went through subsurface-originated or interior inclusion-induced failure. On the contrary, it was shown that surface-induced failure prevailed in the QT-processed steel without spheroidized carbide. The results suggest spheroidized carbide may strengthen the tempered martensitic matrix of the bearing steel and concentrate the stress around an inclusion rather than at the surface, allowing for prolonged fatigue life over the steel without spheroidized carbide. 相似文献
96.
Flexible sodium‐ion supercapacitor based on polypyrrole/carbon electrode by use of harmless aqueous electrolyte for wearable devices 下载免费PDF全文
With the emergence of various wearable devices, supercapacitors have gained immense attention because of their fast response rates. However, most supercapacitors use hazardous electrolyte materials, such as H2SO4, KOH, and acetonitrile. Leakage of these types of electrolytes during use would be very harmful to human skin. Therefore, a supercapacitor that does not employ hazardous materials is an attractive option for use in the energy‐storage components of wearable devices. Herein, we successfully demonstrate a Na‐ion supercapacitor (NISC) with a polypyrrole/carbon‐coated heat‐treated carbon felt electrode and an aqueous 0.4 M NaCl electrolyte, which is not harmful. Furthermore, our NISC with polypyrrole/carbon‐coated heat‐treated carbon felt exhibits a high specific capacitance (31.09 F g?1) and a fast response rate (chargeable at 0.5‐s intervals). The proposed NISC with no harmful materials in the electrolyte has an excellent response rate. It will establish useful guidelines for the energy‐storage components in wearable devices Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
97.
Eun-Jeong Jeong Nam Keun Lee Jisun Oh Seong Eun Jang Jai-Sung Lee In-Hyu Bae Hyun Hee Oh Hoo Kil Jung Yong-Seob Jeong 《Food science and biotechnology》2014,23(4):1193-1198
The antifungal effects of essential oils (EOs) on cultures of the known cheese fungal contaminants Penicillium spp. were evaluated. Cinnamon leaf and bark EOs were the most effective among 8 EOs tested. The main components of both cinnamon EOs were eugenol, cinnamaldehyde, and linalool. Both inhibited growth of Penicillium spp. at a concentration of 10% v/v (2,000 ppm/mm2) on a lawn cell plate. When tested using 3 commercially available cheese starters, cinnamon EOs showed no effect against the FD-DVS ABT-5 cheese starter. However, growth of lactobacilli was inhibited in the presence of ≥10% (v/v) of leaf and bark EOs for the KAZU 1 starter, and ≥5% (v/v) for the FD-DVS FLORA-DANICA starter. A concentration of 4,000 ppm/mm2 of cinnamon EOs completely inhibited growth of the Penicillium spp. that naturally contaminates the surface of Appenzeller cheese. 相似文献
98.
Jun-Ho Bae Moon-Saeng Kim Beom-Cheol Hwang Chul Kim 《International Journal of Precision Engineering and Manufacturing》2010,11(2):299-307
In this paper, permanent magnets are used to remove magnetic sludge in the condenser of the power plant. To obtain the flow
characteristics and magnetic information that are needed for determining a proper design of the magnetic sludge removal apparatus,
we performed numerical simulations through the use of two commercial codes, ANSYS Workbench-Emag and CFX. We also performed
experiments on various kinds and sizes of magnets to obtain the magnetic information through a gauss meter. By analyzing the
results of simulations and experiments, the minimum magnetic force that is able to remove the any size of the magnetic sludge
in the condenser was calculated, and the design of the removal apparatus was confirmed. We made the test model which was confirmed
by the simulations and experiments for the tests of efficiency of the removal apparatus. After testing, the test results were
compared with those of numerical simulations and have good agreements. 相似文献
99.
Hongsub Bae Tanveer Ahmad Ilsu Rhee Yongmin Chang Seong-Uk Jin Sungwook Hong 《Nanoscale research letters》2012,7(1):44
Coprecipitated ferrite nanoparticles were coated with carbon using a hydrothermal method. From transmission electron microscope
pictures, we could see that the coated iron oxide nanoparticles were spherical in shape with an average diameter of 90 nm.
The strong bonding of carbon on the nanoparticle surfaces was checked by noting the C = O and C = C vibrations in Fourier
transform infrared spectra. The spin-lattice relaxation process [T
1] and spin-spin relaxation process [T
2] relaxivities of hydrogen protons in the aqueous solution of coated nanoparticles were determined to be 1.139 (mM·s)-1 and 1.115 (mM·s)-1, respectively. These results showed that the carbon-coated iron oxide nanoparticles are applicable as both T
1 and T
2 contrast agents in magnetic resonance imaging. 相似文献
100.
A power‐efficient 600‐mVpp voltage‐mode driver with independently matched pull‐up and pull‐down impedances 下载免费PDF全文
Woorham Bae Deog‐Kyoon Jeong 《International Journal of Circuit Theory and Applications》2015,43(12):2057-2071
In this study, a large‐swing, low‐power voltage‐mode driver with independently matched pull‐up and pull‐down impedances is proposed. To achieve large swing and constant impedances during a transition, a P‐over‐N structure is implemented with regulators calibrating the impedances. Two regulators are dedicated to matching the pull‐up and pull‐down impedances by regulating the supply voltages of the driver and predriver, respectively. Because background impedance calibration loops are adopted to track the process, voltage, and temperature (PVT) variations, the proposed driver can operate properly without additional calibration time. To reduce the power consumption of the calibration loops, scaled replicas of the actual driver are used. Moreover, an analysis of design optimization for the proposed driver is presented. The proposed driver was fabricated in 65‐nm CMOS technology and verified at a 5‐Gb/s data rate. Measurement results show that the proposed driver has a voltage swing of 600 mVpp and a horizontal eye opening of 0.5 UI. The prototype chip consumes 6 mW at a 1.0‐V supply. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献