全文获取类型
收费全文 | 1639篇 |
免费 | 36篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 103篇 |
综合类 | 1篇 |
化学工业 | 356篇 |
金属工艺 | 39篇 |
机械仪表 | 51篇 |
建筑科学 | 38篇 |
能源动力 | 66篇 |
轻工业 | 136篇 |
石油天然气 | 1篇 |
无线电 | 136篇 |
一般工业技术 | 310篇 |
冶金工业 | 286篇 |
原子能技术 | 38篇 |
自动化技术 | 119篇 |
出版年
2023年 | 5篇 |
2022年 | 11篇 |
2021年 | 29篇 |
2020年 | 14篇 |
2019年 | 22篇 |
2018年 | 26篇 |
2017年 | 15篇 |
2016年 | 25篇 |
2015年 | 13篇 |
2014年 | 25篇 |
2013年 | 67篇 |
2012年 | 66篇 |
2011年 | 114篇 |
2010年 | 75篇 |
2009年 | 46篇 |
2008年 | 67篇 |
2007年 | 67篇 |
2006年 | 62篇 |
2005年 | 58篇 |
2004年 | 60篇 |
2003年 | 39篇 |
2002年 | 53篇 |
2001年 | 25篇 |
2000年 | 24篇 |
1999年 | 33篇 |
1998年 | 127篇 |
1997年 | 72篇 |
1996年 | 60篇 |
1995年 | 38篇 |
1994年 | 28篇 |
1993年 | 31篇 |
1992年 | 18篇 |
1991年 | 18篇 |
1990年 | 22篇 |
1989年 | 14篇 |
1988年 | 20篇 |
1987年 | 12篇 |
1986年 | 15篇 |
1985年 | 17篇 |
1984年 | 18篇 |
1983年 | 15篇 |
1982年 | 11篇 |
1981年 | 13篇 |
1980年 | 12篇 |
1979年 | 13篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1976年 | 14篇 |
1975年 | 10篇 |
1974年 | 4篇 |
排序方式: 共有1680条查询结果,搜索用时 0 毫秒
1.
Masami Ikeda Susumu Fukumoto Hiroshi Takao Shinya Ohtsuka Eiichi Haginomori Masayuki Hikita 《Electrical Engineering in Japan》2002,141(4):16-24
This paper describes the dielectric breakdown characteristics of oil and oil‐impregnated paper for very fast transient (VFT) voltages. Blumlein circuits generate VFT voltages of 60 and 300 ns in a pulse width that simulates disconnecting switching surges in gas‐insulated switch gears. We measured the breakdown voltages of needle‐to‐plane, plane‐to‐plane oil gaps and several pieces of paper between plane electrodes for VFT and lightning impulse voltages. The measured data were formulated in V‐t characteristics and Weibull probability distributions. The inclination n of V‐t characteristics of insulating paper is 150, which is less than n = 13.7 of the plane‐to‐plane oil gap in the VFT time range. The shape parameters of Weibull distribution obtained in this study show that the scattering of breakdown voltages of paper is much less than that of oil. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(4): 16–24, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10043 相似文献
2.
Anumberoflanthanideternarycomplexescon tainingheterocyclicamineshavebeenreportedsince1960 [1] .Inrecentyearsmuchattentionhasbeenpaidtoquaternarycomplexesoflanthanidesbecauseofin terestingstructure ,coordinationmode ,competitionre actionandproperty[2~ 9] .ESRcane… 相似文献
3.
Takashi Yamazaki Yoichi Takino Ryosuke Matsuoka Susumu Ito 《Electrical Engineering in Japan》1993,113(8):26-36
According to the recent analysis results of temporary ac overvoltage in the ac system connected with a frequency converter station, large-magnitude over-voltages were confirmed to occur under some special system conditions. Most of the station insulators currently used cannot withstand such overvoltages according to an evaluation based on the data obtained earlier. The necessity of tests to be done to evaluate such performance more accurately was recognized. Both power frequency and switching impulse overvoltage flashover tests were made on contaminated insulators by the method well simulating the natural wetting condition. Switching impulse flashover voltage with the waveshape having a long wavefront time of 2 ms can be well correlated with the flashover voltage characteristics of temporary ac overvoltage. Higher flashover voltage characteristics were obtained by a clean fog test method compared with those obtained by equivalent fog test method. 相似文献
4.
Masako Yudasaka Rie Kikuchi Takeo Matsui Yoshimasa Ohki Mark Baxendale Susumu Yoshimura Etsuro Ota 《Thin solid films》1996,280(1-2):117-123
Thin film formation of graphite by chemical vapor deposition using 2-methyl-1,2′-naphthyl ketone as a starting material was carried out on Ni film substrates. On Ni films directly deposited on quartz glass, the graphite films were obtained when the Ni film thickness was above 1 000 Å and above 5 000 Å at 700 °C and 1 000 °C, respectively. Depositions on thinner Ni film substrates comprise amorphous carbon (a-C) or graphite tubes which was owing to the thermal coagulation of the Ni film into droplets. On the other hand, graphite film was obtained on the Ni film with thickness 10 Å when a-C was inserted between the Ni film and the quartz glass. The coagulation of the Ni film is considered to be avoided by inserting a-C layer. 相似文献
5.
Comparative studies on Ar and He closed-cycle MHD power plants combined with fossil fuel are performed. The sizes of a regenerative heat exchanger and a boiler are expected to be smaller for He than for Ar. The pressure loss of a working gas in a regenerative heat exchanger is reduced for He. The purification subsystem for He is expected to be more compact and economical than that for Ar; but a larger compressor is required for He than for Ar. 相似文献
6.
We investigated Au catalysts supported on TiO2, Fe2O3, and ZnO for their preferential oxidation of CO in a H2-rich atmosphere. Both full conversion and selectivity were achieved over Au/Fe2O3 and Au/ZnO around room temperature, but at higher temperatures the CO conversion was suppressed due to competition between CO and H2. 相似文献
7.
Fukuda H. Ebara M. Kobayashi A. Sugiura N. Yoshikawa M. Saisho H. Kondo F. Yoshino S. Yahagi T. 《IEEE transactions on bio-medical engineering》1998,45(3):396-400
To objectively evaluate the parenchymal echo pattern of cirrhotic liver and chronic hepatitis, the authors applied an image analyzing system (IAS) using a neural network. Autopsy specimens in a water tank (n=13) were used to examine the relationship between the diameter of the regenerative nodule and the coarse score (CS) calculated by IAS. CS was significantly correlated with the diameter of the regenerative nodule (p<0.0001, r=0.966). CS is considered to be useful for evaluating the coarseness of the parenchymal echo pattern 相似文献
8.
The three-dimensional dynamics of two interacting quantized vortex filaments is studied. The equations of motion and the method of numerical calculation follow Schwarz. Whether two approaching filaments reconnect or not depends on their arrangement before approach. When a ring moves toward a line from a distance, only within a critical initial distance they can reconnect. The critical distance is minimized when their circulations are parallel at the closest place, while it increases as their circulations begin to deviate from being parallel. Hence the reconnection probability can be less than unity. 相似文献
9.
In the first half of the paper, various types of processing pertaining to a polygon, using the 4×4 determinant theories are explained along with a new containment test algorithm of a point in a polygon. In the latter half of the paper, a general-purpose geometric processor, the POLYGON ENGINE, is presented which can deal with various types of interference problems, such as Boolean operations in solid modelling, hidden line and surface eliminations, ray tracing and so on. It is, a successor of the TRIANGLE PROCESSOR and is also based upon the 4×4 determinant theories [4–6]. While the TRIANGLE PROCESSOR processes a triangulated polygon on a triangle-by-triangle basis, the POLYGON ENGINE can treat a polygon without triangulation. The latter is expected to be more functional, more efficient and easier to use. 相似文献
10.
Susumu Onaka Masaharu Kato T. Mori 《Metallurgical and Materials Transactions A》1986,17(11):1949-1953
Steady-state sliding of grain boundaries is discussed by taking into account the change in the potential energy of an applied
stress, when the sliding occurs by diffusional accommodation. The present analysis enables us to derive the sliding rates
at boundaries of various shapes in a simple manner without knowing local stress fields. Sliding rate of a boundary containing
second phase particles is also derived by similar calculations. The results are compared with previous calculations by other
investigators, and it is found that the resultant expressions for the sliding rates are essentially identical to those derived
from more complex analyses. 相似文献