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1.
Tribological Characteristics of SiC Ceramics in High-Temperature and High-Pressure Water 总被引:2,自引:0,他引:2
Satoshi Kitaoka Toshihide Tsuji Toshio Katoh Yoshimi Yamaguchi† Kazumi Kashiwagi 《Journal of the American Ceramic Society》1994,77(7):1851-1856
The effects of temperature and sliding speed on the tribological behavior of a SiC ceramic by sliding on the same material in deoxygenated water were investigated from room temperature to 300°C under the corresponding saturated vapor pressures. The friction coefficient and specific wear rates of both plates and disks increased at elevated temperatures at all sliding speeds, but decreased with increasing sliding speed at 120° and 300°C. Fine mirrorlike worn surfaces were observed without wear debris under all sliding conditions. The wear mechanism appears to consist of hydrothermal oxidation of SiC and dissolution of reaction products such as silica. 相似文献
2.
3.
Parametric embedding for class visualization 总被引:1,自引:0,他引:1
Iwata T Saito K Ueda N Stromsten S Griffiths TL Tenenbaum JB 《Neural computation》2007,19(9):2536-2556
We propose a new method, parametric embedding (PE), that embeds objects with the class structure into a low-dimensional visualization space. PE takes as input a set of class conditional probabilities for given data points and tries to preserve the structure in an embedding space by minimizing a sum of Kullback-Leibler divergences, under the assumption that samples are generated by a gaussian mixture with equal covariances in the embedding space. PE has many potential uses depending on the source of the input data, providing insight into the classifier's behavior in supervised, semisupervised, and unsupervised settings. The PE algorithm has a computational advantage over conventional embedding methods based on pairwise object relations since its complexity scales with the product of the number of objects and the number of classes. We demonstrate PE by visualizing supervised categorization of Web pages, semisupervised categorization of digits, and the relations of words and latent topics found by an unsupervised algorithm, latent Dirichlet allocation. 相似文献
4.
The stability region of the helical textures in3He-A in thev
s-H phase diagram is theoretically determined. Herev
sis the superflow velocity andH (v
s) is the external magnetic field. The pitch of the helixk
–1 that minimizes the Gibbs free energy and the corresponding inclination angles ofl andd are determined numerically as functions ofv
sandH. The NMR frequencies (two longitudinal and four transverse frequencies) associated with the helical texture are obtained.Work supported by the National Science Foundation under Grant No. DMR 76-21032. 相似文献
5.
Bias-temperature stress examinations of self-aligned 0.1 μm length gate GaAs MESFETs have revealed a shift of threshold voltage related to Si doping concentration near the gate sides next to the channel region. With lower doping concentration, the increase in threshold voltage in FETs was faster and a 100 mV increase leads to a 20% reduction of operation speed in digital ICs after forward-biased storage at 200°C. The recovery of the performance under reverse-biased stresses was observed. The degradation is released by increasing Si doping concentration and thus we obtained the prediction of a median life exceeding 106 h at 100°C by setting the Si dose of 4 × 1013 cm−2, which is as high as it can be set without causing serious reduction of breakdown voltage. 相似文献
6.
AgGaTe2 and AgAlTe2 layers were grown on a-plane sapphire substrates by closed-space sublimation. These compounds replace Cd in CdTe with group I and III elements, and are, hence, expected to be ideal novel candidate materials for solar cells. The grown layers were confirmed to be stoichiometric AgGaTe2 and AgAlTe2 by x-ray diffraction (XRD). The AgAlTe2 layers had strong preference for the (112) orientation. The XRD spectrum of the AgGaTe2 layer was different from that of the AgAlTe2 layer, and strong peaks were observed for (103) and (110) diffraction. The variation in orientations of the grown layers was analyzed in detail by use of XRD pole figures, which revealed that the AgGaTe2 layers had an epitaxial relationship with the a-plane sapphire substrates. 相似文献
7.
Yoshiaki Kinemuchi Ken-ichi Mimura Atsuya Towata Kazumi Kato 《Journal of Electronic Materials》2014,43(6):2011-2016
A giant Seebeck coefficient of ?890 μV/K at 500 °C has been observed in Y0.2Sr0.8TiO3 prepared using nanocubes. Doping rare earth elements, RE, has revealed that small RE is effective to enhance the Seebeck coefficient. Through soft mode observations by Raman spectroscopy and structural calculations based on density functional theory, it has been found that the breakdown of inversion symmetry of the perovskite structure near the surface of nanocubes can be recovered by doping with small RE. Because the dielectric constant is strongly related to the surface structure in this compound, we suggest that RE doping modulates the potential barrier at the grain boundary, resulting in a pronounced energy filtering effect in Y doped SrTiO3. 相似文献
8.
Masaaki Haneda Ohki Houshito Hiromitsu Takagi Kiyoshi Shinoda Yuunosuke Nakahara Kazumi Hiroe Tadahiro Fujitani Hideaki Hamada 《Topics in Catalysis》2009,52(13-20):1868-1872
The activity of Rh/CeO2 for NO reduction by C3H6 was gradually deceased by mixing with ZrO2 until 68 mol%. Rh supported on CeO2–ZrO2 with higher OSC was found to show lower catalytic activity. High OSC of CeO2–ZrO2 would probably stabilize the surface of Rh in oxidized state, resulting in low activity and low efficiency of C3H6 utilization for NO reduction. In situ FT-IR spectroscopy suggested that mononitrosyl species such as Rh(NO)δ? and Rh(NO)δ+ are reaction intermediates in the NO–C3H6–O2 reaction over Rh/CeO2–ZrO2 catalysts. 相似文献
9.
The effect of nonproportional strain path on fatigue/creep-fatigue properties was investigated with 304 stainless steel at 550°C under strain controlled biaxial conditions. The fatigue/creep-fatigue life reduction due to nonproportional strain path occurred even at the lowest strain range investigated, that is, 0.2% for fatigue loading and 0.3% for creep-fatigue loading. The Mises-type path-dependent equivalent strain range was employed in order to evaluate the fatigue/creep-fatigue strength under nonproportional loading conditions. Stress relaxation behavior under nonproportional loading was examined. It was shown that stress relaxes proportionally toward the origin of stress plane even under nonproportional loading. Fatigue damage and creep damage were calculated based on the linear damage summation rule. Life prediction was shown to be possible within an accuracy of a factor of about 2 for nonproportional loading along with other waveforms including pure axial loading, pure torsional loading and combined proportional loading. 相似文献
10.
Yoshitake Masuda Kazumi Kato Masahito Kida Jun Otsuka 《International Journal of Applied Ceramic Technology》2019,16(5):1807-1811
SnO2 nanosheets were developed to detect nonanal gas in the order of ppb which was a marker of lung cancer. The nanosheets showed higher resistance change in nonanal gas than that in carbon monoxide (CO), nitrogen dioxide (NO2), acetone (CH3COCH3), hydrogen (H2), ethanol (C2H6O), ammonia (NH3), hydrogen sulfide (H2S), formaldehyde (HCHO), acetaldehyde (CH3CHO), or butanal (C4H8O). Crystal surfaces of the nanosheets would be effective for adsorption of nonanal molecules. Furthermore, it was shown that resistance changed with an increase in carbon number in aldehyde. The nanosheets had molecular selectivity for a series of aldehyde molecules. Molecular recognition of the nanosheets gave us a great advantage to detect nonanal gas which was produced by lung cancer. 相似文献