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91.
Tetsuya Suemitsu Yoshino K. Fukai Hiroki Sugiyama Kazuo Watanabe Haruki Yokoyama 《Microelectronics Reliability》2002,42(1):47-52
The reliability of InP-based HEMTs is studied, focussing on how it is affected by the doped layer material and gate recess structure. Bias-and-temperature stress tests reveal that fluorine-induced donor passivation in the recess region, formed adjacent to the gate electrode, causes the source resistance (Rs) to increase at large drain bias voltages. The increase in Rs can be prevented by using InP or InAlP as the carrier supply layer material instead of InAlAs. On the other hand, the increase in the drain resistance (Rd) does not depend on the material of the carrier supply layer, which suggests that a mechanism different from that in the case of Rs should be considered. It is also found that a deep gate recess suppresses the increase in Rd after long-term stressing. 相似文献
92.
Fast Labelling of Natural Scenes Using Enhanced Knowledge 总被引:1,自引:0,他引:1
Hiroki Hayashi Mineichi Kudo Jun Toyama Masaru Shimbo 《Pattern Analysis & Applications》2001,4(1):20-27
A new technique for labelling natural scenes is proposed. This technique labels disjoint regions on an image of a natural
scene on the basis of knowledge about the relationship among objects. The proposed technique consists of three stages: (1)
segmentation, (2) initial labelling, and (3) label improvement. One of the most promising previous techniques uses simulated
annealing to find the solution, while our technique uses local hill-climbing with enhanced knowledge for speeding up the processing.
Local hill-climbing is known to be easy to be captured by a local minimum. We solved this problem by enhancing the knowledge
being used as constraints for the search. Our knowledge represents 1-to-n relationships among regions, pair-wise relationships of regions, and relative locations of the regions to the image. In addition,
we introduced two region features: an entropy in intensity; and a linearity of contours of each region. The linearity evaluation
aims to distinguish artificial objects from natural objects. The validity of the technique is supported by some experiments.
These experiments showed that the proposed technique is much faster with the almost same accurate. 相似文献
93.
94.
K. Yamagata K. Nishikawa S. Hasegawa T. Fujii S. Yoshida 《International Journal of Heat and Mass Transfer》1972,15(12):2575-2593
Experimental investigations were made of heat transfer to supercritical water flowing in a horizontal tube and vertical tubes. A comprehensive set of data was obtained for pressures from 226 to 294 bar, bulk temperatures from 230 to 540°C, heat fluxes from 116 to 930 kW/m2 and mass velocities from 310 to 1830 kg/m2s. Because the physical properties of supercritical fluids change rapidly with temperature in the pseudocritical region, the heat transfer coefficients show unusual behavior depending upon the heat flux. At low or modetate heat fluxes relatively to the flow rate, a satisfactory correlation was obtained, which predicts reasonably well the enhanced heat transfer coefficients near the pseudocritical point. The several characteristics of the deterioration in heat transfer which occurs at high heat fluxes were clarified, and the limit heat flux for the occurrence of the deterioration was determined in connection with the flow rate. 相似文献
95.
Hiroki Nagasawa Akihiro Yamasaki Atsushi Iizuka Kazukiyo Kumagai Yukio Yanagisawa 《American Institute of Chemical Engineers》2009,55(12):3286-3293
Bipolar membrane electrodialysis is applied to CO2 recovery from alkaline carbonate solution. CO2 in flue gas is captured by an alkaline hydroxide absorbing solution to form an alkaline carbonate solution. The captured CO2 is recovered from the alkaline carbonate solution via bipolar membrane electrodialysis, and the alkaline solution is regenerated simultaneously. To reduce the power requirement for CO2 recovery, this study considers optimal design and operation. Three membrane arrangements were compared, and the results indicate the membrane arrangement comprising a bipolar membrane and cation exchange membrane is the most energy saving. With further optimization of operation conditions, the minimum power requirement for CO2 recovery was reduced to 2.1 MJ/kg‐CO2 (or 2.1 GJ/t‐CO2). © 2009 American Institute of Chemical Engineers AIChE J, 2009 相似文献
96.
97.
The contribution of Fe to C2S polymorphs is effectively revealed for β-C2S formation and is not for α′- or α-C2S. However in co-existing of Na or K with Fe, the α-C2S is easily stabilized, though accompanied with small amount of crystalline Ca2Fe2O5 as the interstitial material. This effect of Fe on α- and β-C2S synthesis was investigated by XRD, chemical analysis and Mössbauer spectra observation. Comparing calculated Mössbauer parameters of α- and β-C2S with those of other minerals, it was confirmed that they included only Fe3+ at octahedral and tetrahedral sites with the ratio 30:70 in Na---Fe substituted α-form and with 63:37 in K---Fe substituted α-form. In β-C2S, Fe3+ was mostly situated at tetrahedral site. The formulas of α- and β-C2S were decided and shown as, (Ca1.88Fe0.05Na0.24)(Si0.88Fe0.11)O4, (Ca1.94 Fe0.09K0.18) (Si0.88Fe0.05)O4 for α-form and (Ca1.93Fe0.003Na0.04) (Si0.99Fe0.05)O4, (Ca1.94Fe0.01K0.04) (Si0.92Fe0.13)O4 for -form. 相似文献
98.
Yuki Matsushita Junko Taniguchi Ryo Toda Hiroki Ikegami Taku Matsushita Mitsunori Hieda Nobuo Wada 《Journal of Low Temperature Physics》2008,150(3-4):342-346
We have studied heat capacities of 4He adsorbed in straight nanopores 1.8, 2.2, and 2.8 nm in diameter. Heat capacities of the 4He fluid film on the solid layer at 0.08–0.4 K show power laws close to T in 1.8 nm pores, close to T
2 in 2.8 nm pores, and a crossover from T to T
2 with increasing temperature in 2.2 nm pores. These heat capacities are explained by a model assuming a phonon dispersion
with continuous one-dimensional (1D) states in the axial direction and discrete energy levels in the azimuthal direction.
By fitting experimental data to the model, the phonon velocity along the pore axis and the energy gap for propagation in the
cross section are derived. At temperatures sufficiently lower than the energy gap, where the thermal wave length of phonons
is much longer than the effective pore diameter, the 4He fluid films show a T-linear heat capacity of 1D phonons propagating only along the pore axis. At higher temperatures, a 1D-2D crossover of phonons
occurs.
相似文献
99.
Shingo Hasegawa Shuji Isobe Hiroki Shizuya Katsuhiro Tashiro 《International Journal of Information Security》2009,8(5):347-355
The notion of pseudo-free group was first introduced by Hohenberger (Master’s thesis, EECS Dept., MIT, 2003). Rivest (TCC
2004. LNCS 2951, 505–521, 2004) formalized it and showed that several standard cryptographic assumptions hold on pseudo-free groups, such
as the RSA assumption, the strong RSA assumption and the discrete logarithm assumption. Rivest (TCC 2004. LNCS 2951, 505–521, 2004) also proposed some variations of pseudo-free group, and those were formalized by Hirano and Tanaka (Research
Reports, Series C: Computer Science, C-239, Tokyo Institute of Technology, 2007). In this paper, we study the relationships
among such variations of pseudo-free group. We show that the pseudo-freeness implies the weak pseudo-freeness, and that the
pseudo-freeness is equivalent to the pseudo-freeness with generalized exponential expressions. We also show that the computational
Diffie-Hellman assumption holds on pseudo-free groups in a slightly varied form. 相似文献
100.
Independent component analysis (ICA) is a technique of transforming observation signals into their unknown independent components; hence, ICA has often been applied to blind signal separation problems. In this application, it is expected that the obtained independent components extract essential information of independent signal sources from input data in an unsupervised fashion. Based on such characteristics, ICA is currently utilized as a feature extraction method for images and sounds for recognition purposes. However, since ICA is an unsupervised learning, the obtained independent components are not always useful in recognition. To overcome this problem, we propose a supervised approach to ICA using category information. The proposed method is implemented in a conventional three‐layered neural network, but its objective function to be minimized is defined not only for the output layer but also for the hidden layer. The objective function consists of the following two terms: one evaluates the kurtosis of hidden unit outputs and the other evaluates the error between output signals and their teacher signals. The experiments are performed using several standard datasets to evaluate performance of the proposed algorithm. It is confirmed that a higher recognition accuracy is attained by the proposed method as compared with a conventional ICA algorithm. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(2): 25–32, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20522 相似文献