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111.
Daisuke Hiramatsu Yoichi Uemura Shinji Uemoto Junji Okumoto Takehiko Imai Mikio Kakiuchi Ken Nagakura Masafumi Fujita Toru Otaka 《Electrical Engineering in Japan》2011,177(3):17-27
Two‐pole large generators are extensively used in power utilities. Growing demand for electric power in recent years has led to substantial increases in the capacity of generators. In line with this trend, our company has manufactured two‐pole turbine generators in the 900,000‐kVA to 1,200,000‐kVA classes. As the capacity of generators becomes larger, equivalent circuits are increasingly expected to improve their precision in estimating operation characteristics. The Park model has been widely used as an equivalent circuit model. The Park model with quadrature axis transient reactance $x_{q}^{prime}$ is claimed to be useful for accurately estimating the load rejection characteristics of turbine generators. However, it is difficult to measure $x_{q}^{prime}$, few studies based on measured data have appeared. As one of the few examples, we have conducted a measured data on a 500,000‐kVA‐class generator. Recently, the authors obtained test data on $x_{q}^{prime}$ of a 900,000‐kVA‐class generator. In this study, based on these data, we studied the effect of $x_{q}^{prime}$ using the finite element method and a transient analysis program (EMTP‐ATP). © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 177(3): 17–27, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21099 相似文献
112.
Fukuda M. Noguchi Y. Motosugi G. Nakano Y. Tsuzuki N. Fujita O. 《Lightwave Technology, Journal of》1987,5(12):1778-1781
In InGaAsP/InP buried heterostructure (BH) lasers, the degradation of BH interface between first- and second-growth step layers can be suppressed by employing the melt back process just before the second-step layer growth. It is confirmed this burying process give more reliable BH lasers than the conventional burying process. From the viewpoint of BH interface degradation, lasers lasing at 1.5 μm, where the melt back process naturally occurs during BH formation, are found to be more reliable than those lasing at 1.3 μm. 相似文献
113.
The water wettability and non-wettability onto various kinds of polymers, which have so far been macroscopically described by the water contact angle, were investigated using the molecular orbital theory. An atomistic model consisting of an H2O molecule and a selected polymer crystal surface was analyzed in the isolated and the physisorbed states. The degree of interaction between the water molecule and the polymer surface was evaluated by considering the change of Mulliken charge at the oxygen site in the water molecule, and also the work of adhesion during the physisorption process. Such energetic quantities for several polymers were compared with the macroscopic water wettability/non-wettability. We found fairly good agreement between these approaches for the highly non-wettability polymers. 相似文献
114.
Satoshi Azuma Hisanori Yamasaki Daisuke Itoh Takafumi Maruyama 《Electrical Engineering in Japan》2008,165(4):84-91
A newly proposed energy‐compensating active control is implemented to reduce the return current noise which is caused by inverter‐driven electric car systems. The energy‐compensating active control detects the energy charged at the filter capacitor, and reduces the energy and current of the noise frequency component by simple feedback loop incorporated with the conventional motor torque controller. No additional sensors or circuit arrangements are necessary; therefore, the return current can be attenuated effectively without any further cost. The return current with an inverter system is measured using a current probe and an FFT analyzer, and it is shown that the 25‐Hz noise current is reduced by up to 10 dB with the control. The results reveal that the low‐frequency return current noise can be attenuated with the simple control scheme, which would expectedly reduce the size of filter reactors and capacitors to meet the current limit level of the signaling system's track relays. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(4): 84–91, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20615 相似文献
115.
116.
An experimental evaluation of spatial distribution for deeply penetrating protons in carbon material
Mitsuo Tosaki Daisuke Ohsawa Yasuhito Isozumi 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2005,230(1-4):59-62
The peak profile of the 4.8-MeV resonance by the 12C(p,p)12C reaction in backscattering geometry has been analyzed to examine two kinds of stragglings of proton, i.e. the depth straggling in the incoming path and the energy loss straggling in the outgoing path. The analysis, which is combined with existing theoretical treatments for the stopping process and the energy loss straggling, has made it possible to deduce the penetration depth and its spread at the resonance position in carbon materials. The present method, as a new tool for direct inspection of ion beams inside target material, is explained in detail. 相似文献
117.
For a vertical plunging liquid jet system using various liquids, the effects of the operating conditions including the nozzle length-to-diameter ratio on the gas entrainment rate Qg were evaluated experimentally. The differences in Qg were related to the changes in the jet shape before plunging and the velocity of the plunging liquid jet at the point where the gas sheath breaks up. Empirical relationships were also presented to predict the maximum depth Z of bubbles entrained by the diffusing jet. The changes of Z were further discussed in terms of the downward liquid velocity distribution in the submerged two-phase region, which depends mainly on the size of entrained bubbles. 相似文献
118.
119.
Kazushi Yawata Daisuke Ito Hiroki Ikegami Hidehiko Ishimoto Hiroshi Fukuyama 《Journal of Low Temperature Physics》1998,113(5-6):769-774
Experimental methods and preliminary results of high-precision measurements of the
3
He melting curve in high magnetic fields have been described. The purpose of this work is twofold. One is to establish a reliable millikelvin temperature scale in high fields (T 10 mK, B 15 T), The other is to investigate a high field region of the magnetic phase diagram of solid
3
He by measuring the melting pressure down to temperatures below 1 mK. Besides the two superfluid transitions, the phase transition temperatures between the spin ordered solid and the paramagnetic solid, T
HFP
, were determined at B = 12 and 10 T with good accuracy, which is an extension of previous measurements up to 8 T. The present T
HFP
(B) line can not be scaled to that at a higher density with a single Grüneisen parameter, indicating a variation of density dependencies of the multiple-spin exchange interactions. 相似文献
120.
The possible influencing factors for diamond formation which prevent non-graphitic carbons from transforming to diamond in the presence of nickel as solvent-catalyst were pursued. The relative amount of nickel to carbon did not affect the behaviour of each starting carbon on diamond formation. The existence of a graphitic structure in the starting carbon was not the major prerequisite for diamond formation. Adsorbed gases on the starting carbon and atmospheric gases in the high pressure cell were found to be the most important influencing factors for diamond formation. Hydrogen and chemical species containing hydrogen atoms were the most harmful. 相似文献