全文获取类型
收费全文 | 504篇 |
免费 | 23篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 51篇 |
综合类 | 2篇 |
化学工业 | 152篇 |
金属工艺 | 27篇 |
机械仪表 | 19篇 |
建筑科学 | 10篇 |
能源动力 | 21篇 |
轻工业 | 31篇 |
水利工程 | 1篇 |
无线电 | 26篇 |
一般工业技术 | 120篇 |
冶金工业 | 17篇 |
原子能技术 | 13篇 |
自动化技术 | 43篇 |
出版年
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 13篇 |
2020年 | 4篇 |
2019年 | 9篇 |
2018年 | 9篇 |
2017年 | 7篇 |
2016年 | 17篇 |
2015年 | 8篇 |
2014年 | 18篇 |
2013年 | 35篇 |
2012年 | 13篇 |
2011年 | 26篇 |
2010年 | 15篇 |
2009年 | 35篇 |
2008年 | 32篇 |
2007年 | 18篇 |
2006年 | 26篇 |
2005年 | 27篇 |
2004年 | 18篇 |
2003年 | 14篇 |
2002年 | 18篇 |
2001年 | 5篇 |
2000年 | 17篇 |
1999年 | 14篇 |
1998年 | 8篇 |
1997年 | 14篇 |
1996年 | 8篇 |
1995年 | 12篇 |
1994年 | 11篇 |
1993年 | 12篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有533条查询结果,搜索用时 0 毫秒
51.
A high frequency model of transformer winding is used to analyze the voltage oscillations due to various excitations such as the very fast transient overvoltage which occurs at the time of disconnecting switch operations. Usually, a circuit of interlinked inductances and capacitances is used for this purpose, in which circuit parameters have to be properly determined. Previously, those constants have been estimated taking the coil section pair as a unit. In the method proposed here, the section pair can be further subdivided. The time‐domain calculation is conducted combining the frequency analysis and FFT technique. The voltage oscillations of the winding subjected to the lightning impulse are calculated. The correspondence with the experimental results is satisfactory. The response to a chopped impulse shows this method's applicability to high frequency analysis. Since the constants are calculated directly from the design parameters of transformer winding, this technique is particularly useful in developing and designing transformers. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(3): 8–16, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10280 相似文献
52.
Satoshi Hirosawa Ken Makita Yoshikazu Kanekiyo Minoru Umemoto 《Electrical Engineering in Japan》1994,114(4):13-21
Hard magnetic properties of nitrogen interstitially modified NdMxFe12-xNy compounds and Fe3B-based ultra-fine crystalline Nd? Fe? Co? T? B alloys of low Nd content of 3 to 5 at. % are studied. The nitrogen-modified compounds have been prepared via the rapid solidification route and the mechanical alloying route both followed by gas nitrogenation using N2. The Fe3B-based materials have been prepared by means of rapid solidification and crystallization treatment. The latter materials appear promising as the base material for high-remanence, easy-to-magnetize bonded magnets with small temperature coefficients of remanence. Typical magnetic properties of compaction isotropic bonded magnets produced from this material are Br = 0.80 T, HcJ = 350 kA/m, and (BH)max = 60.5 kJ/m3. 相似文献
53.
Shikano H. Ito M. Onouchi M. Todaka T. Tsunoda T. Kodama T. Uchiyama K. Odaka T. Kamei T. Nagahama E. Kusaoke M. Nitta Y. Wada Y. Kimura K. Kasahara H. 《Solid-State Circuits, IEEE Journal of》2008,43(4):902-910
This paper describes a heterogeneous multi-core processor (HMCP) architecture that integrates general-purpose processors (CPUs) and accelerators (ACCs) to achieve exceptional performance as well as low-power consumption for the SoCs of embedded systems. The memory architectures of CPUs and ACCs were unified to improve programming and compiling efficiency. Advanced audio codec-low complexity (AAC-LC) stereo audio encoding was parallelized on a heterogeneous multi-core having homogeneous processor cores and dynamically reconfigurable processor (DRP) ACC cores in a preliminary evaluation of the HMCP architecture. The performance evaluation revealed that 54times AAC encoding was achieved on the chip with two CPUs at 600 MHz and two DRPs at 300 MHz, which achieved encoding of an entire CD within 1- 2 min. 相似文献
54.
H Kodama Y Kodama S Shinozawa R Kanemaru K Todaka Y Mitsuyama 《Canadian Metallurgical Quarterly》1998,23(5):361-365
Recently a German appraisal instrument for clinical guidelines was published that could be used by various parties in formal evaluation of guidelines. An user's guide to the appraisal instrument was designed that contains a detailed explanation for each question to ensure that the instrument is interpreted consistently. This paper describes the purposes, format and contents of the user's guide, and reviews the key factors influencing the validity of guidelines. Taking into account international experiences, the purposes, chances and methodological limitations of a prospective assessment of clinical practice guidelines are discussed. 相似文献
55.
The numerical implementation of the boundary-element method formulated for 3-D eddy-current problems is presented. In particular, the algorithm for solving these problems, together with the formulation for the magnetic vector potential and the electric potential using the Lorentz gauge, is discussed in detail. Based on accurate calculations of the numerical solution at interior points in the neighborhood of the boundary, the revised integration method shown earlier by the authors (1988) is extended to this 3-D magnetic field analysis for the steady-state 相似文献
56.
Study on explosion characteristics of natural gas and methane in semi-open space for the HTTR hydrogen production system 总被引:1,自引:0,他引:1
Yoshitomo Inaba Tetsuo Nishihara Mark A Groethe Yoshikazu Nitta 《Nuclear Engineering and Design》2004,232(1):111-119
It is important to grasp the explosion characteristics of object gases: natural gas and methane, in order to evaluate the influence of a gas explosion accident in the HTTR hydrogen production system on the reactor. Thus, we carried out explosion experiments of the object gases in semi-open space, and verified a numerical analysis code for the simulation of the explosion accident. It was confirmed that NG–air mixture or methane-air mixture in semi-open space did not result in DDT although 10 g of C-4 explosive was used as an ignition source, and the numerical results agreed relatively with the experimental results. As a result, we could have the prospects for predicting the influence of the explosion accident on the reactor. 相似文献
57.
This paper presents an application of parallel genetic algorithms (PGA) to the optimal long-range generation expansion planning. The problem can be formulated as a combinatorial optimization problem that determines the order of introduced generation units at each interval of the year. The proposed method considers introduced power limits of each technology, maximum loads at each interval, and load duration curves at each interval. Appropriate string representation for the problem is presented. Binary and decimal coding and three selection methods are compared. The method is developed on a transputer that is one of the parallel processors. The feasibility of the proposed method is demonstrated using a typical expansion problem with four technologies and five intervals. The method is then compared with conventional dynamic programming and a simple genetic algorithm with promising results. 相似文献
58.
1IntroductionCharacterswerecreatedasamediumofcommunication.Forexample,theyhavebeenusedtorecordsocialactivitiesandhumanthinking,andtohelppeoplesexchangeinformation.Differencesfrommanyothercharacters,however,theChi-nesecharacterisatypicalideograph.BecauseChinesecharactersoriginatedfromdrawings,theirshapeshavetheelementsofbeauty.InChina,calligraphyaboutChinesecharactershasbeenanimportanpartofartsinceancienttimes.There-sultsofstudiesaboutcalligraphyhavebeenbequeathedascalligraphicworksandcallig… 相似文献
59.
Toshihiko Nishida Yoshikazu Hanaki Taketoshi Nojima Giuseppe Pezzotti 《Journal of the American Ceramic Society》1995,78(11):3113-3116
A simple procedure for measuring the R -curve properties of ceramics by a stable fracture test in three-point bending is described. As a typical case, data are displayed for a Si3 N4 material toughened by the presence of acicular grains in situ grown during the sintering process. The fracture mechanics specimen was a single-edge double-notched beam (SEDNB), whose notch was sharpened to a radius of <10 μm in order to reduce the amount of elastic energy stored at its root prior to crack extension. Furthermore, a stabilizer, specially designed for the bending geometry, was used to control crack stability. During stable extension, the crack could be easily arrested at selected locations of the load-displacement curve, the load quickly released, and the stable crack extension directly measured by the die-penetration technique. The crack resistance, K R , of the material was calculated from the measured crack extent and the onset load value before unloading. This method enabled us to precisely monitor the critical load value at which the load-displacement curve deviated from linear behavior, as well as crack extensions from a few tens of micrometers to about 1 mm. As an application of this method, the fracture resistance of a Si3 N4 material with rising R -curve behavior was measured and found to increase from about 5.5 to 9.0 MPaμm1/2 within a 0.8-mm extension. 相似文献
60.