全文获取类型
收费全文 | 1881篇 |
免费 | 33篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 81篇 |
综合类 | 1篇 |
化学工业 | 338篇 |
金属工艺 | 45篇 |
机械仪表 | 36篇 |
建筑科学 | 26篇 |
能源动力 | 51篇 |
轻工业 | 109篇 |
水利工程 | 5篇 |
石油天然气 | 1篇 |
无线电 | 220篇 |
一般工业技术 | 301篇 |
冶金工业 | 529篇 |
原子能技术 | 32篇 |
自动化技术 | 141篇 |
出版年
2023年 | 10篇 |
2022年 | 17篇 |
2021年 | 25篇 |
2020年 | 12篇 |
2019年 | 24篇 |
2018年 | 22篇 |
2017年 | 12篇 |
2016年 | 24篇 |
2015年 | 18篇 |
2014年 | 41篇 |
2013年 | 73篇 |
2012年 | 61篇 |
2011年 | 46篇 |
2010年 | 45篇 |
2009年 | 71篇 |
2008年 | 69篇 |
2007年 | 52篇 |
2006年 | 48篇 |
2005年 | 65篇 |
2004年 | 54篇 |
2003年 | 53篇 |
2002年 | 42篇 |
2001年 | 45篇 |
2000年 | 35篇 |
1999年 | 54篇 |
1998年 | 213篇 |
1997年 | 121篇 |
1996年 | 84篇 |
1995年 | 55篇 |
1994年 | 39篇 |
1993年 | 45篇 |
1992年 | 25篇 |
1991年 | 31篇 |
1990年 | 31篇 |
1989年 | 30篇 |
1988年 | 20篇 |
1987年 | 21篇 |
1986年 | 23篇 |
1985年 | 17篇 |
1984年 | 13篇 |
1983年 | 12篇 |
1982年 | 10篇 |
1981年 | 10篇 |
1980年 | 15篇 |
1979年 | 15篇 |
1978年 | 11篇 |
1977年 | 16篇 |
1976年 | 21篇 |
1975年 | 4篇 |
1970年 | 4篇 |
排序方式: 共有1916条查询结果,搜索用时 0 毫秒
1.
Tatsuro Tanaka Yoshifumi Maeda Shinji Yamamoto Toru Iwao 《Electrical Engineering in Japan》2019,207(1):15-23
The arc welding has been used in various welding methods because it is inexpensive and high in strength after welding. However, it is a problem that accidents such as collapse of the bridge occur because of the welding defects. The welding of low cost and high productivity is required without the welding defects. The pulsed TIG welding is inexpensive and capable of high‐quality welding. The electromagnetic force contributing to penetration changes because the transient response of arc temperature and iron vapor generated from anode occurs. However, the analysis of pulsed TIG welding with metal vapor has been elucidated only metal vapor concentration near anode with transient phenomenon and heat flux. Thus, the theoretical elucidation of penetration depth with control factor has not been researched. In this paper, the contribution of metal vapor mass at the periphery part of pulsed arc to the electromagnetic force in the weld pool is elucidated. As a result, the iron vapor mass at periphery part decreased with increasing the frequency. The iron vapor was stagnated at axial center within one cycle. The electromagnetic force to the penetration depth direction in weld pool increased at axial center. Therefore, the metal vapor mass at periphery part plays an important role for the electromagnetic force increment at axial center. 相似文献
2.
The In-site of Ba2In2O5 with Brownmillerite structure was partially substituted for Ce4+ ions in order to examine the doping effect on the order-disorder transition. Ba2In2 – x
Ce
x
O5 + x/2 (x = 0.1, 0.2, 0.3, 0.5, 1.0, and 1.5) were prepared by solid state reaction. X-Ray diffraction analyses of these powder samples demonstrated that Ba2In2 – x
Ce
x
O5 + x/2 (x = 0.1 and 0.2) possesses Brownmillerite structure. With increasing content of Ce4+ ion the crystal system of Ba2In2 – x
Ce
x
O5 + x/2 (x = 0.3, 0.5, and 1.0) changed to cubic perovskite structure above the order-disorder transition temperature of Ba2In2O5. Arrhenius plots of the electrical conductivities of Ba2In2 – x
Ce
x
O5 + x/2 (x = 0.2, 0.3, and 1.0) exhibited no discontinuity. These compounds had high transference numbers of oxide ion above 973 k. 相似文献
3.
H Asahara K Fujisawa T Kobata T Hasunuma T Maeda M Asanuma N Ogawa H Inoue T Sumida K Nishioka 《Canadian Metallurgical Quarterly》1997,40(5):912-918
Green fluorescent protein (GFP) is increasingly being used in plant biology from the cellular level to whole plant level. At the cellular level, GFP is being used as an in vivo reporter to assess frequency of transient and stable transformation. GFP has also proven to be an invaluable tool in monitoring trafficking and subcellular localization of protein. At the organ level and up, many exciting applications are rapidly emerging. The development of brighter GFP mutants with more robust folding properties has enabled better macroscopic visualization of GFP in whole leaves and plants. One interesting example has been the use of GFP to monitor virus movement in and among whole plants. GFP is also emerging as a powerful tool to monitor transgene movement and transgenic plants in the field. In a proof-of-concept study, tobacco was transformed with a modified version of the GFP gene controlled by a constitutive (35S) promoter. GFP expression in progeny plants ranged from 0% to 0.5%, and approximately 0.1% GFP was the minimal amount needed for unambiguous macroscopic detection. GFP is the first truly in vivo reporter system useful in whole plants, and we project its usefulness will increase even further as better forms of GFP genes become available. 相似文献
4.
Yamaoka M. Shinozaki Y. Maeda N. Shimazaki Y. Kato K. Shimada S. Yanagisawa K. Osada K. 《Solid-State Circuits, IEEE Journal of》2005,40(1):186-194
An on-chip 1-Mb SRAM suitable for embedding in the application processor used in mobile cellular phones was developed. This SRAM supports three operating modes - high-speed active mode, low-leakage low-speed active mode, and standby mode - and uses a subdivisional power-line control (SPC) scheme. The combination of three operating modes and the SPC scheme realizes low-power operation under actual usage conditions. It operates at 300 MHz, with leakage of 25 /spl mu/A/Mb in standby mode, and 50 /spl mu/A/Mb at the low-leakage active mode. This SRAM also uses a self-bias write scheme that decreases of minimum operating voltage by about 100 mV. 相似文献
5.
6.
Takeshi Kondo Hiroyuki Ito Kazuhide Kusakabe Kazuhiro Ohkawa Kensuke Honda Yasuaki Einaga Akira Fujishima Takeshi Kawai 《Diamond and Related Materials》2008,17(1):48-54
The effect of CF4 plasma etching on diamond surfaces, with respect to treatment time, was investigated using scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. SEM observations and Raman spectra indicated an increase in surface roughening on a scale of 10–20 nm, and an increase in crystal defect density was apparent with treatment time in the range of 10 s to 30 min. In contrast, alteration of the diamond surface terminations from oxygen to fluorine was found to be rather rapid, with saturation of the F/C atomic ratio estimated from XPS analysis after treatment durations of 1 min and more. The redox kinetics of Fe(CN)63−/4− was also found to be significantly modified after 10 s of CF4 plasma treatment. This behavior shows that C–F terminations predominantly affect the redox kinetics compared to the effect on the surface roughness and crystal defects. The double-layer capacitance (Cdl) of the electrolyte/CF4 plasma-treated boron-doped diamond interface was found to show a minimum value at 1 min of treatment. These results indicate that a short-duration CF4 plasma treatment is effective for the fabrication of fluorine-terminated diamond surfaces without undesirable surface damage. 相似文献
7.
The authors derive the systolic array implementation of the block LMS algorithm, consisting of N processing elements, where N is the filter order. The resulting array attains an order-independent sampling rate. Computer simulation results show that the block LMS algorithm is faster than the delayed LMS algorithm, which has previously been implemented on systolic arrays 相似文献
8.
9.
Sixiong Han Yasuaki Ichikawa 《International journal for numerical methods in engineering》1995,38(24):4081-4100
In this paper, a mathematical model is proposed for the problem of the scattering of plane waves in a three-dimensional cracked materials. Instead of obtaining closed-form solutions as in conventional theoretical analysis methods, this approach, called the Equivalent Nodal Force (ENF) method formulates the mechanical effects of cracks as an equivalent nodal force in a numerical procedure, and physically translates cracked material into an equivalent continuous one. Several mechanical relations between waves and cracks are evident from this method. Also the results of several numerical calculations are presented and these are compared with those obtained by the conventional methods. 相似文献
10.
S Ohkawa A Yamadori K Maeda M Tabuchi Y Ohsumi E Mori T Yoshida Y Yoneda T Uehara 《Canadian Metallurgical Quarterly》1993,56(8):894-896
In right middle cerebral territory infarction a new sign, excessive closure of the right eye ipsilateral to the lesion and mild closure of the left eye on command, was noted. The excessive ipsilateral eye closure was not observed on spontaneous eye closure. 相似文献