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101.
Nakagawa Y Saito A Maeno T 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2008,55(3):717-725
In this paper, nonlinear dynamic response of a traveling wave-type ultrasonic motor was investigated. In particular, understanding the transient dynamics of a bar-type ultrasonic motor, such as starting up and stopping, is of primary interest. First, the transient response of the bar-type ultrasonic motor at starting up and stopping was measured using a laser Doppler velocimeter, and its driving characteristics are discussed in detail. The motor is shown to possess amplitude-dependent nonlinearity that greatly influences the transient dynamics of the motor. Second, a dynamical model of the motor was constructed as a second-order nonlinear oscillator, which represents the dynamics of the piezoelectric ceramic, stator, and rotor. The model features nonlinearities caused by the frictional interface between the stator and the rotor, and cubic nonlinearity in the dynamics of the stator. Coulomb's friction model was employed for the interface model, and a stick-slip phenomenon is considered. Lastly, it was shown that the model is capable of representing the transient dynamics of the motor accurately. The critical parameters in the model were identified from measured results, and numerical simulations were conducted using the model with the identified parameters. Good agreement between the results of measurements and numerical simulations is observed. 相似文献
102.
103.
F. Nakamura K. Yoshida Y. Tanaka X. Z. Bao Y. Maeno T. Fujita 《Journal of Superconductivity》1994,7(1):33-35
In La2–x
Ba
x
CuO4 (LBCO), the structural transition to a low-temperature tetragonal phase below 60 K and suppression of superconductivity are observed when the carrier density isp 1 /8 per copper. The replacement by divalent ions smaller than Ba2+ suppresses the static deformation of the lattice. We have found that the variationsT
d2
and superconducting transition temperatureT
c
are quantitatively characterized by the averaged ionic radius at the La site or lattice parameters. This aspect of substitution could be regarded as the effect of chemical pressure, since similar variations have been reported on applying hydrostatic pressure. In La2–x–y
Nd
y
(Ba, Sr)
x
CuO4,T
d2
increases with increasingy in a wide range ofp whileT
c
is suppressed only at p l /8. The structural transition atT
d2
here should be ascribed mainly to the crystallochemical origin. 相似文献
104.
Satoshi Takahashi Yuichiro Miki Kazuo Maeno Noriyuki Hirayanagi Kazuhiro Maeda Motoharu Tateishi 《Precision Engineering》2005,29(3):347-353
In this paper, an approach is presented for the computation of the in-plane pattern placement error (PPE) caused by the wafer heating during exposure of electron projection lithography (EPL) using the finite element method (FEM), which is one of candidates in the next-generation lithography (NGL) exposure tools. The PPE is the global and local distortion, and is the thermo-mechanical response due to the thermal deformation of the wafer in the lithography process. The prediction of PPE requires high accuracy for NGL exposure tools. The simultaneous estimation of the global and local PPE to the whole wafer of a full three-dimensional FE model using a solid element requires excessive computation time. A novel technique of numerical simulation is developed and proposed, which is the employment of a shell element combined with previously proposed the dynamic meshing technique (DMT), being possible to predict PPE in realistic computation time with high accuracy. Simulations are performed for the wafer heating of EPL effectively using three techniques, that is the equivalent average heating technique and two proposed techniques. The simulation results agree closely with the result of a full three-dimensional FE analysis, and the required computation time becomes 1/16 or much less of that. 相似文献
105.
YI Arshavsky TG Deliagina GN Gamkrelidze GN Orlovsky YV Panchin LB Popova 《Canadian Metallurgical Quarterly》1993,69(2):522-532
1. A contact of the pteropod mollusk Clione limacina with its prey (small pteropod mollusk Limacina helicina) evokes a complex pattern of hunting and feeding behavior: protraction of tentacles to seize the prey, activation of buccal apparatus to swallow the prey, activation of locomotor system (speeding up of wing beating), reversal of reaction to tactile stimulation of the head, loss of normal (vertical) orientation in space, and swimming in circles. After injection of physostigmine (PhS), the acetylcholinesterase inhibitor, into the hemocoel of intact Clione, all these manifestations of the hunting and feeding behavior could be evoked by tactile stimulation of the head, or they arose spontaneously. 2. In the preparation of the isolated CNS, the effect of PhS on the neural networks controlling different aspects of the hunting and feeding behavior was studied by recording from neurons monitoring activity of different networks (< or = 4 neurons simultaneously). Tactile stimulation of the head was mimicked by a short-term electrical stimulation of the corresponding nerve. Before PhS application, the nerve stimulation evoked elements of the defense reaction, i.e., long-lasting inhibition of all main motor control systems: the locomotor network in the pedal ganglia, the tentacle control network in the cerebral ganglia, and the network controlling radula and hook movements in the buccal ganglia. However, after PhS application, the same stimulus evoked a long-lasting bout of excitation in all the three networks accompanied by activation of the heart-exciting neuron as well as by a modification of the activity of statocyst receptor cells controlling Clione's spatial orientation (the "fictive hunting bout"). Similar hunting bouts could arise spontaneously. 3. Injection of acetylcholine (ACh) into the hemocoel of intact Clione was less effective than injection of PhS. After ACh injection, reversal of reaction to head stimulation was observed in < or = 20% of the experiments (the percentage of positive results was higher if ACh was injected into the head just over the CNS). Bath application of ACh to the isolated CNS did not produce the hunting bouts. However, a short-term local application of ACh to the cerebral ganglia in the isolated CNS resulted in activation of the main motor systems controlling locomotion, protraction of tentacles, and movements of buccal mass. 4. During spontaneous PhS-induced bouts, excitation of different networks involved in hunting behavior was sometimes not quite synchronous. Different networks could be excited in variable order over a period of up to several seconds.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
106.
Markus Kriener Takahiro Muranaka Junya Kato Zhi-An Ren Jun Akimitsu Yoshiteru Maeno 《Science and Technology of Advanced Materials》2008,9(4)
The discoveries of superconductivity in heavily boron-doped diamond in 2004 and silicon in 2006 have renewed the interest in the superconducting state of semiconductors. Charge-carrier doping of wide-gap semiconductors leads to a metallic phase from which upon further doping superconductivity can emerge. Recently, we discovered superconductivity in a closely related system: heavily boron-doped silicon carbide. The sample used for that study consisted of cubic and hexagonal SiC phase fractions and hence this led to the question which of them participated in the superconductivity. Here we studied a hexagonal SiC sample, free from cubic SiC phase by means of x-ray diffraction, resistivity, and ac susceptibility. 相似文献
107.
Fukuma M. Fukunaga K. Maeno T. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2001,8(2):304-306
Space charge dynamics in low-density polyethylene (LDPE) films were observed by the pulsed electroacoustic (PEA) method during breakdown tests at various temperatures. In order to investigate the intrinsic electrical breakdown, the applied electric field was increased to 300 kV/mm in 150 ms, and kept constant until breakdown of the specimens, or 300 ms at the longest. Space charge profiles were measured at 1 ms intervals. A significant positive charge propagating into the sample was observed only immediately before the breakdown at 90°C. These measurements revealed that the positive charge behavior is strongly related to the breakdown phenomena 相似文献
108.
针对垃圾渗滤液的高浓度、难降解、具有生物毒性的特点,采用混凝沉降法对其进行处理,以处理出水的CODcr为处理程度的表征指标。通过正交实验,确定最佳复合混凝剂的试剂用量,比较不同反应条件对CODcr去除率的影响,优化操作条件。实验结果表明,最佳复合混凝剂:1 250 mg/LPAC+1 500 mg/LPFS+50 mg/L PAM;最佳条件:pH=7.0,搅拌时间为15 min,沉降时间为20 min;CODcr去除率达到66.9%。 相似文献
109.
110.