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51.
In this work, we develop an alternative discrete ordinate approximation for radiative transfer in a refractive slab. The present method treats the angular derivative term of the radiative transfer equation for a planar medium with varying refractive index (VRI) by using a finite Legendre transform which gives a simple expression of the angular derivative term. Thus, the solution procedure does not march along direction, and so is not restricted to a monotonic variation of refractive index. We apply this method to study radiative heat transfer in a cold slab with anisotropic scattering, diffuse boundaries and sinusoidal VRI. We also solve the problems by the discrete curved ray tracing (DCRT). The hemispherical reflectance and transmittance of slabs with irradiation from the upper surroundings obtained by the present method and those obtained by the DCRT are in excellent agreement. For a slab of a sinusoidal refractive index with the minimum at the center plane, the gradient of refractive index causes the internal reflection of a part of irradiation, which reduces the transmittance of the slab. Other effects of the VRI, the optical thickness, the scattering albedo, the anisotropically scattering coefficient and the boundary reflection are also investigated.  相似文献   
52.
Negative bias temperature instability (NBTI) degradation mechanism in body-tied low-temperature polycrystalline silicon thin-film transistors (LTPS TFTs) is analyzed by the charge-pumping (CP) technique. The properties of bulk trap states (including interface and grain boundary trap states) are directly characterized from the CP current. The increase of the fixed oxide charges is also extracted, which has not been quantified in previous studies of NBTI degradation in LTPS TFTs. The experimental results confirm that the NBTI degradation in LTPS TFTs is caused by the generation of bulk trap states and oxide trap states.  相似文献   
53.
Chondrosarcoma is the primary malignancy of bone that is characterized by a potent capacity to invade locally and cause distant metastasis, and is therefore associated with poor prognoses. Chondrosarcoma further shows a predilection for metastasis to the lungs. The brain-derived neurotrophic factor (BDNF) is a small molecule in the neurotrophin family of growth factors that is associated with the disease status and outcome of cancers. However, the effect of BDNF on cell motility in human chondrosarcoma cells is mostly unknown. Here, we found that human chondrosarcoma cell lines had significantly higher cell motility and BDNF expression compared to normal chondrocytes. We also found that BDNF increased cell motility and expression of matrix metalloproteinase-1 (MMP-1) in human chondrosarcoma cells. BDNF-mediated cell motility and MMP-1 up-regulation were attenuated by Trk inhibitor (K252a), ASK1 inhibitor (thioredoxin), JNK inhibitor (SP600125), and p38 inhibitor (SB203580). Furthermore, BDNF also promoted Sp1 activation. Our results indicate that BDNF enhances the migration and invasion activity of chondrosarcoma cells by increasing MMP-1 expression through a signal transduction pathway that involves the TrkB receptor, ASK1, JNK/p38, and Sp1. BDNF thus represents a promising new target for treating chondrosarcoma metastasis.  相似文献   
54.
An oblique flat surface model is used lo simulate the rotating roll. The flow regions proposed by Landau and Levich is utilized in the analysis. The inertia force terms are included and a more realistic 2-dimensional boundary conditions for the free surface is used in this paper. Also, the solution is obtained by utilizing a refinement of integral method. The results are compared with available experimental data. It is shown that the prediction is sufficiently accurate over a wide range of capillary number, and better than the other existing results. The film thickness increase with respect to increasing capillary number up to a certain higher values, from then this tendency slows down and even decreases due to inertia effects  相似文献   
55.
Esculetin (ESC) is a coumarin that is present in several plants such as Fraxinus rhynchophylla and Artemisia capillaris. Our previous study found that FR ethanol extract (FR(EtOH)) significantly ameliorated rats' liver function. This study was intended to investigate the protective mechanism of ESC in hepatic apoptosis in rats induced by carbon tetrachloride. Rat hepatic apoptosis was induced by oral administration of CCl(4). All rats were administered orally with CCl(4) (20%, 0.5 mL/rat) twice a week for 8 weeks. Rats in the ESC groups were treated daily with ESC, and silymarin group were treated daily with silymarin. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) as well as the activities of the anti-oxidative enzymes glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase in the liver were measured. In addition, expression of liver apoptosis proteins and anti-apoptotic proteins were detected. ESC (100, 500 mg/kg) significantly reduced the elevated activities of serum ALT and AST caused by CCl(4) and significantly increased the activities of catalase, GPx and SOD. Furthermore, ESC (100, 500 mg/kg) significantly decreased the levels of the proapoptotic proteins (t-Bid, Bak and Bad) and significantly increased the levels of the anti-apoptotic proteins (Bcl-2 and Bcl-xL). ESC inhibited the release of cytochrome c from mitochondria. In addition, the levels of activated caspase-9 and activated caspase-3 were significantly decreased in rats treated with ESC than those in rats treated with CCl(4) alone. ESC significantly reduced CCl(4)-induced hepatic apoptosis in rats.  相似文献   
56.
Traditional background model methods often require complicated computations, and are sensitive to illumination and shadow. In this paper, we propose a block-based background modeling method, and use our proposed method to combine color and texture characteristics. Suppression and relaxation are the two key strategies to resist illumination changes and shadow disturbance. The proposed method is quite efficient and is capable of resisting illumination changes. Experimental results show that our method is suitable for real-word scenes and real-time applications.  相似文献   
57.
The apical four-chamber view echocardiogram collected by a transthoracic transducer can be used to evaluate the left ventricle volume. In the diastole, the left ventricle and left atrium become one chamber. In this case, the left ventricle and left atrium need to be separated using a "mitral annular line" so the volume of the left ventricle can be estimated. In this paper, a nearly automatic method for identifying the mitral annular lines from two-dimensional (2-D) + one-dimensional (1-D) precordial four-chamber view echocardiogram is presented. This method employs the optical flow technique and graph-search approach. The mitral annular line sequence is found by finding the shortest path in a weighted directed graph. The vertices in the graph are candidates for the mitral annular lines. The weights on the directed edges are determined using the optical flow technique. The proposed method requires only a physician to provide a point that is always in the left ventricular chamber. Experimental results show that the average error for the left ventricle volume obtained based on the computed mitral annular lines is 3%.  相似文献   
58.
In this paper, nonpolar resistive switching behavior is reported for the first time in a SZO-based memory device. The electrode materials used which have different conductivities affect the resistive switching properties of the device. The Al/V:SZO-LNO/Pt device shows nonpolar switching behavior, whereas the Al/V:SZO/LNO device has bipolar switching property. The resistance ratios of these two devices are quite distinct owing to the difference between the resistance of low resistance states. The Al/V:SZO-LNO/Pt device with lower resistive switching voltages (mnplus7 V turn on and mnplus2 V turn off) and higher resistance ratio is more suitable for practical applications compared to the Al/V:SZO/LNO device. The switching speed of the Al/V:SZO-LNO/Pt device is 10 ns, which is the fastest speed that has ever been reported. The conduction mechanisms, nondestructive readout property, retention time, and endurance of this device are also reported in this paper.  相似文献   
59.
In this work, we design, fabricate and compare three types of three-stream curved-straight-curved (CSC) micromixers, including the full three-stream (FTS) CSC micromixer, the CSC microchannel with internal side-wall injection and the CSC microchannel with external side-wall injection. In the three-stream CSC micromixers, there is a core stream sandwiched by two cladding streams into the CSC channel with baffles from two inlets. The sandwiched structure of streams and the multidirectional vortices due to flow separation and channel curvature contribute together to enhance mixing. We examine fluid mixing in the proposed micromixers by numerical simulation and using confocal spectral microscope imaging system. The present results show that the mixing efficiency increases without increasing the pressure applied much by the channel structure forming the sandwiched structure of streams. Besides, it is found that the FTS CSC micromixer is the preferable one among the micromixers considered.  相似文献   
60.
This paper proposes a complete control law comprising an evolutionary programming based kinematic control (EPKC) and an adaptive fuzzy sliding-mode dynamic control (AFSMDC) for the trajectory-tracking control of nonholonomic wheeled mobile robots (WMRs). The control gains for kinematic control (KC) are trained by evolutionary programming (EP). The proposed AFSMDC not only eliminates the chattering phenomenon in the sliding-mode control, but also copes with the system uncertainties and external disturbances. Additionally, the convergence of trajectory-tracking errors is proved by the Lyapunov stability theory. Computer simulations are presented to confirm the effectiveness of the proposed complete control law. Finally, real-time experiments are done in the test field to demonstrate the feasibility of real WMR maneuvers.  相似文献   
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