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1.
Threshold energies for sputtering cannot be calculated directly but have to be evaluated from the energy dependence of the sputtering yields. This paper investigates trajectories of projectile and recoils near the threshold energy for sputtering, where the collision cascade becomes increasingly simple. Statistics of the different collision events show which processes dominate the sputtering close to the threshold energy for selfbombardment of different light and heavy targets. The differential cross-sections for scattering and recoil production explain qualitatively the probability for the various processes. 相似文献
2.
The application of municipal solid waste (MSW) compost increases both the trace metal loading and the organic matter in the soil. To characterize the quality and metal-binding capacity of the compost OM, we extracted humic acid (HA) and fulvic acid (FA) from mature MSW compost and analyzed them for elemental composition, acid-titratable functional groups, total metal content, and structural components (by 13C NMR). HA constituted 67% of all extracted humic substances and differed significantly from HAs of cultivated lands: The compost HA exhibited smaller molecular size, a higher N content, and lower aromaticity due to large amounts of saturated aliphatic components. Metal complexation studies of the extracted HA and FA were performed by equilibrium dialysis titration. The complexing capacity (CC) was highest for Cu: CCHA = 3357 and CCFA = 5221 μmol Cu g−1 of dissolved organic carbon (DOC) at pH 5. Zn and Cd were bound (at pH 7) in smaller concentrations: CCHA(Zn) = 2167, CCFA(Zn) = 2809, CCHA(Cd) = 2386, and CCFA(Cd) = 2468 μmol metal g−1 of DOC. Stability constants for binding on the strongest sites (pKint) were determined as pKintHA = 6.6 and pKintFA = 7.3 for Cu at pH 5; and pKintHA = 8.0 and pKintFA = 6.4 for Cd at pH 7. Since these measured parameters fall within the ranges of values obtained for soil humic substances, we conclude that in soils with little organic matter, compost addition will significantly increase the amount of highly reactive organic complexing agents for trace metals in the soil. 相似文献
3.
This paper is part of a larger investigation of the role of amines in the adhesion of polybutadiene to glass substrates. It describes near infrared, infrared and nuclear magnetic resonance spectroscopy studies of the interaction of amines with silanol groups usually under ambient conditions but sometimes when heated in air. Additional supporting evidence was obtained from gas liquid chromatography, mass spectrometry and elemental analyses. In order to assure a sufficiently high concentration of silanol groups, triethylsilanol and fused silica were used as models for the glass surface. The mechanism of interaction of aliphatic amines and of the aminosilane was different from that of aromatic amines. Most notably, reaction of aliphatic amines with carbon dioxide in the air and/or dissolved/adsorbed in/on the silanol occurred almost instantaneously, whereas the corresponding reaction of the aromatic amines with carbon dioxide was not observed under the experimental conditions used. The carbamates formed underwent further reactions much more rapidly than either the simple aromatic amines or the unmodified aliphatic amines. 相似文献
4.
New fit formulae for the sputtering yield 总被引:1,自引:0,他引:1
5.
Kyohei Kurohane Akie Uehara Tomonobu Senjyu Atsushi Yona Naomitsu Urasaki Toshihisa Funabashi Chul-Hwan Kim 《Renewable Energy》2011,36(1):42-49
This paper deals with a DC-micro-grid with renewable energy. The proposed method is composed of a gearless wind power generation system, a battery, and DC loads in a DC distribution system. The battery helps to avoid the DC over-voltages by absorbing the power of the permanent magnet synchronous generator (PMSG) during line-fault. In addition, the control schemes presented in this paper including the maximum power point tracking (MPPT) control and a pitch angle control for the gearless wind turbine generator. By means of the proposed method, high-reliable power can be supplied to the DC distribution system during the line-fault and stable power supply from the PMSG can be achieved after line-fault clearing. The effectiveness of the proposed method is examined in a MATLAB/Simulink® environment. 相似文献
6.
A wind turbine generator (WTG) system's output is not constant and fluctuates depending on wind conditions. Fluctuating power causes frequency deviations and adverse effects to an isolated power system when large output power from WTG systems is penetrated in the power system. This paper presents an output power control methodology of a WTG for frequency control using a load power estimator. The load power is estimated by a disturbance observer, and the output power command of the WTG is determined according to the estimated load. Besides, the WTG can also be controlled during wind turbulence since the output power command is determined by considering wind conditions. The reduction of the power system frequency deviation by using the WTG can be achieved by the proposed method. The effectiveness of the proposed method is validated by numerical simulations. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
7.
Akie Uehara Tomonobu Senjyu Toshiaki Kaneko Atsushi Yona Endusa Billy Muhando Naomitsu Urasaki Chul‐Hwan Kim 《风能》2010,13(7):671-684
Nowadays, a wind turbine generator (WTG) is required to provide control capabilities as the output power of WTG fluctuates. Under this scenario, this paper proposes an output power control method of a wind farm (WF) connected to a small power system using pitch angle control. In this control approach, the WF output power control is achieved by two control levels: central and local. In the central control, the WF output power command is determined by considering the frequency deviations and wind speeds using a fuzzy function. Then, the local output power commands for each of the WTGs are based on the proposed dispatch control. In the proposed dispatch control, the output commands of each WTG are determined by considering wind conditions for each of the WTGs. The simulation results by using an actual detailed model for the wind power system show the effectiveness of the proposed method. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
8.
Bochud FO Abbey CK Eckstein MP 《Journal of the Optical Society of America. A, Optics, image science, and vision》2000,17(2):193-205
Models of human visual detection have been successfully used in computer-generated noise. For these backgrounds, which are generally statistically stationary, model performance can be readily calculated by computing the index of detectability d' from the noise power spectrum, the signal profile, and the model template. However, model observers are ultimately needed in more real backgrounds, which may be statistically non-stationary. We investigated different methods to calculate figures of merit for model observers in real backgrounds based on different assumptions about image stationarity. We computed performance of the nonpre-whitening matched-filter observer with an eye filter on mammography and coronary angiography for an additive or a multiplicative signal. Performance was measured either by applying the model template to the images or by computing closed-form expressions with various assumptions about image stationarity. Results show first that the structured backgrounds investigated cannot be considered stationary. Second, traditional closed-form expressions of detectability calculated from the noise power spectra with the assumption of background stationarity lead to erroneous estimates of model performance. Third, the most accurate way of measuring model performances is by directly applying the model template on the images or by computing a closed-form expression that does not assume image stationarity. 相似文献
9.
Abbey CK Eckstein MP 《Journal of the Optical Society of America. A, Optics, image science, and vision》2000,17(11):2101-2104
In a recent paper [J. Opt. Soc. Am. A 17, 206 (2000)], a modified detectability index, d'r, was proposed to accommodate correlations between internal responses in multiple-alternative forced-choice (MAFC) experiments. The derivation given in that work pertained only to two-alternative forced choice, although it was shown empirically that the result held for general MAFC tasks when the correlation between responses is constant. Here we present a rigorous derivation that shows that the d'r result generalizes to MAFC tasks in this case. 相似文献
10.
H.A. Woltermann R.R. Eckstein P.L. Redding S.A. Tomes 《Journal of Nuclear Materials》1974,54(1):117-120
An X-ray fluorescence method for the determination of thorium (0.1 to 1.2 %) in plutonium-238 was developed. The PuO2 is mounted in a dimpled slide, and the slide is packaged so that the plutonium and thorium L-alpha lines can be counted in a nonradioactive laboratory. A standard deviation of 0.02 % is estimated. The method is applicable to both solid and solution samples. 相似文献