全文获取类型
收费全文 | 1965篇 |
免费 | 53篇 |
国内免费 | 14篇 |
专业分类
电工技术 | 173篇 |
综合类 | 4篇 |
化学工业 | 470篇 |
金属工艺 | 85篇 |
机械仪表 | 52篇 |
建筑科学 | 37篇 |
矿业工程 | 5篇 |
能源动力 | 38篇 |
轻工业 | 141篇 |
水利工程 | 6篇 |
石油天然气 | 7篇 |
无线电 | 152篇 |
一般工业技术 | 394篇 |
冶金工业 | 247篇 |
原子能技术 | 68篇 |
自动化技术 | 153篇 |
出版年
2023年 | 8篇 |
2022年 | 7篇 |
2021年 | 17篇 |
2020年 | 22篇 |
2019年 | 18篇 |
2018年 | 22篇 |
2017年 | 23篇 |
2016年 | 22篇 |
2015年 | 34篇 |
2014年 | 48篇 |
2013年 | 122篇 |
2012年 | 70篇 |
2011年 | 92篇 |
2010年 | 79篇 |
2009年 | 71篇 |
2008年 | 105篇 |
2007年 | 77篇 |
2006年 | 61篇 |
2005年 | 66篇 |
2004年 | 71篇 |
2003年 | 54篇 |
2002年 | 54篇 |
2001年 | 53篇 |
2000年 | 48篇 |
1999年 | 34篇 |
1998年 | 110篇 |
1997年 | 80篇 |
1996年 | 56篇 |
1995年 | 39篇 |
1994年 | 41篇 |
1993年 | 40篇 |
1992年 | 19篇 |
1991年 | 20篇 |
1990年 | 22篇 |
1989年 | 25篇 |
1988年 | 20篇 |
1987年 | 23篇 |
1986年 | 25篇 |
1985年 | 20篇 |
1984年 | 20篇 |
1983年 | 23篇 |
1982年 | 33篇 |
1981年 | 23篇 |
1980年 | 23篇 |
1979年 | 26篇 |
1978年 | 17篇 |
1977年 | 9篇 |
1976年 | 17篇 |
1974年 | 7篇 |
1971年 | 3篇 |
排序方式: 共有2032条查询结果,搜索用时 109 毫秒
141.
Keiji Tsukada Mitsuteru Yoshioka Yoshihiko Kawasaki Toshihiko Kiwa 《NDT & E International》2010,43(4):323-328
We have developed a magnetic flux leakage (MFL) system using magnetic resistive (MR) sensors for detecting two dimensional magnetic field components, and an induction coil that generates low magnetic field strengths and extremely low frequencies. The signal at each scanned measurement point (i) was divided by the signal strength Mmes,i and phase αi by a lock-in amplifier. Using the strength Mmes,i and phase αi, we calculated the imaginary part of the signal using the common phase β. By optimization of the common phase β to the imaginary part, the analyzed scanning data curve was shown to be effective in estimating the size (depth and diameter) of back-side pits on a ferrous plate. Comparing the two dimensional magnetic field components of leakage, the imaginary part of the y-component parallel to the induced magnetic field was found to be suitable for detecting the back-side pits. 相似文献
142.
This study was performed to investigate the heat extraction characteristics from shallow geothermal resources using a coaxial heat exchanger. First, a computer simulation program for a coaxial heat exchanger was checked and verified by laboratory experiments. After inspecting the effectiveness of the computer program described herein, a numerical simulation for a real scale model was conducted under the condition that the heat transfer mechanism in the stratum was heat conduction. Unsteady heat extraction characteristics are presented herein, and the effects of the tube material, inner diameter, and circular modes on the heat extraction rate are discussed. From the computer results it was found that the heat extraction performance using a coaxial heat exchanger greatly depended on the factors mentioned above in the range of the parameters covered in this study. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(7): 496–513, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20083 相似文献
143.
144.
145.
Toshiro Sakai Yasuhiro Tanaka Tadashi Fukao Tatsuo Takada Takashi Maeno 《Electrical Engineering in Japan》2008,162(2):10-19
Most of the breakdowns in an electric power system are caused by lightning to the tower used for high‐voltage transmission wires. To avoid accidents due to lightning, it would be desirable to develop a measurement system for the spatial electric field distribution around the tower. We have developed a new system that can measure the electric field around the steel tower for electric power transmission by using an optical electric sensor. In conventional methods, the sensor is generally illuminated by light transmitted by optical fibers. On the other hand, the new measurement system illuminates the Pockels sensor directly by using a laser to measure the far electric field. Furthermore, our newly proposed feedback system makes it possible to measure the spatial electric field without concern for the change of Pockels sensor's operation point influenced by temperature change. This system is applicable as a remote sensing system to monitor the spatial electric field around a high‐voltage transmission line. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(2): 10–19, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20552 相似文献
146.
Kento Nishida Hiroshi Watanabe Ryota Murata Kai Tokumaru Rui Fujimura Shun Oshiro Taisei Nagasaki Masako Miyahisa Yuto Hiramoto Hiroto Nosaki Tadashi Imafuku Hitoshi Maeda Masafumi Fukagawa Toru Maruyama 《International journal of molecular sciences》2021,22(11)
An effective strategy is highly desirable for preventing acute kidney injury (AKI) to chronic kidney disease (CKD) transition. Thioredoxin-1 (Trx), a redox-active protein that has anti-oxidative and anti-inflammatory properties, would be a candidate for this but its short half-life limits its clinical application. In this study, we examined the renoprotective effect of long-acting Trx that is comprised of human albumin and Trx (HSA-Trx) against AKI to CKD transition. AKI to CKD mice were created by renal ischemia-reperfusion (IR). From day 1 to day 14 after renal IR, the recovery of renal function was accelerated by HSA-Trx administration. On day 14, HSA-Trx reduced renal fibrosis compared with PBS treatment. At the early phase of fibrogenesis (day 7), HSA-Trx treatment suppressed renal oxidative stress, pro-inflammatory cytokine production and macrophage infiltration, thus ameliorating tubular injury and fibrosis. In addition, HSA-Trx treatment inhibited G2/M cell cycle arrest and apoptosis in renal tubular cells. While renal Trx protein levels were decreased after renal IR, the levels were recovered by HSA-Trx treatment. Together, HSA-Trx has potential for use in the treatment of AKI to CKD transition via its effects of modulating oxidative stress and inflammation. 相似文献
147.
148.
149.
Application of ultrasonic treating to degassing of metal ingots 总被引:3,自引:0,他引:3
The relations between porosity in the ingot and the effecting factors such as the ultrasonic power and the time of ultrasonic vibration (UV) treating to melt were investigated. Moreover, the mechanism of the porosity formation and the prevention method was studied. The results indicate that the effect of degasification was better when the intensity of UV is above threshold value. On the contrary, the intensity of UV below the value resulted in the increase of the gas content in the ingot and the decrease of density. It could be confirmed that there is an appropriate time on degasification by UV treating. When treating time is over the time, the density of the ingot tended to decrease. By using UV to degas with constraint cooling in the bottom of the ingot, the value of porosity volume (PV) can be decreased below 0.1 cm3/100 g and the ηdeg is near to 97%. 相似文献
150.
Shinji Tsuneyuki Hikaru Kitamura Tadashi Ogitsu Takashi Miyake 《Journal of Low Temperature Physics》2001,122(3-4):291-296
Quantum distributions of protons in three high-pressure phases of solid molecular hydrogen are investigated by the first-principles path integral molecular dynamics (FP-PIMD) method, in which interatomic forces are calculated precisely based on the density functional theory. The distributions have entirely different symmetries from those predicted by conventional simulation with classical treatment of protons. Especially in phase II, we found that molecular rotation is hindered by quantum fluctuation of protons, having a strong resemblance to a quantum distribution of impurity muonium in crystalline silicon. The mechanism of this “quantum localization” is clarified by a detailed study of the potential energy surface for the molecular rotation. 相似文献