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41.
Using the boundary element dual reciprocity method-multi-domain (DRM-MD) a bound electron states and corresponding wave functions in semiconductor quantum wires embedded in a matrix were considered. The single circular and rectangular as well as the two near circular quantum wires were analyzed. In the case of two coupled quantum wires the dependence of the resulting wave function and eigenenergies as a function of the distance between wires was calculated. The DRM-MD gave a linear electron state model and developed numerical approach accurately captured the symmetry breaking and splitting of the degenerated energy states due to presence of additional wire. According to the symmetry of the structures a suitable mesh reduction was employed and different modes were considered separately. For a case of hetero-structures domain decomposition was used. 相似文献
42.
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44.
A thermokinetic model coupling finite-element heat transfer with transformation kinetics is developed to determine the effect
of deposition patterns on the phase-transformation kinetics of laser powder deposition (LPD) process of a hot-work tool steel.
The finite-element model is used to define the temperature history of the process used in an empirical-based kinetic model
to analyze the tempering effect of the heating and cooling cycles of the deposition process. An area is defined to be covered
by AISI H13 on a substrate of AISI 1018 with three different deposition patterns: one section, two section, and three section.
The two-section pattern divides the area of the one-section pattern into two sections, and the three-section pattern divides
that area into three sections. The results show that dividing the area under deposition into smaller areas can influence the
phase transformation kinetics of the process and, consequently, change the final hardness of the deposited material. The two-section
pattern shows a higher average hardness than the one-section pattern, and the three-section pattern shows a fully hardened
surface without significant tempered zones of low hardness. To verify the results, a microhardness test and scanning electron
microscope were used. 相似文献
45.
Raspberry wine fermentation with suspended and immobilized yeast cells of two strains of Saccharomyces cerevisiae 下载免费PDF全文
Radovan Djordjević Brian Gibson Mari Sandell Gustavo M. de Billerbeck Branko Bugarski Ida leskošek‐Čukalović Jovana Vunduk Ninoslav Nikićević Viktor Nedović 《Yeast (Chichester, England)》2015,32(1):271-279
The objectives of this study were to assess the differences in fermentative behaviour of two different strains of Saccharomyces cerevisiae (EC1118 and RC212) and to determine the differences in composition and sensory properties of raspberry wines fermented with immobilized and suspended yeast cells of both strains at 15 °C. Analyses of aroma compounds, glycerol, acetic acid and ethanol, as well as the kinetics of fermentation and a sensory evaluation of the wines, were performed. All fermentations with immobilized yeast cells had a shorter lag phase and faster utilization of sugars and ethanol production than those fermented with suspended cells. Slower fermentation kinetics were observed in all the samples that were fermented with strain RC212 (suspended and immobilized) than in samples fermented with strain EC1118. Significantly higher amounts of acetic acid were detected in all samples fermented with strain RC212 than in those fermented with strain EC1118 (0.282 and 0.602 g/l, respectively). Slightly higher amounts of glycerol were observed in samples fermented with strain EC1118 than in those fermented with strain RC212. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
46.
Assessment of green cleaning effectiveness on polychrome surfaces by MALDI‐TOF mass spectrometry and microscopic imaging 下载免费PDF全文
Stepanka Hrdlickova Kuckova Michaela Crhova Krizkova Catarina Luísa Cortes Pereira Radovan Hynek Olga Lavrova Tito Busani Luis Cobra Branco Irina Crina Anca Sandu 《Microscopy research and technique》2014,77(8):574-585
This article proposes an innovative methodology which employs nondestructive techniques to assess the effectiveness of new formulations based on ionic liquids, as alternative solvents for enzymes (proteases), for the removal of proteinaceous materials from painted surfaces during restoration treatments. Ionic liquids (ILs), also known as “designer” solvents, because of their peculiar properties which can be adjusted by selecting different cation‐anion combinations, are potentially green solvents due totheir low vapour pressure. In this study, two ionic liquids were selected: IL1 (1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIM][BF4])) and IL2 (1‐ethyl‐3‐methylimidazolium ethylsulphate ([EMIM][EtSO4])). New formulations were prepared with these ILs and two different proteases (E): one acid (E1—pepsin) and one alkaline (E2—obtained from Aspergillus sojae). These formulations were tested on tempera and oil mock‐up samples, prepared in accordance with historically documented recipes, and covered with two different types of protein‐based varnishes (egg white and isinglass—fish glue). A noninvasive multiscale imaging methodology was applied before and after the treatment to evaluate the cleaning's effectiveness. Different microscopic techniques—optical microscopy (OM) with visible and fluorescent light, scanning electron microscopy (SEM) and atomic force microscopy (AFM)—together with Matrix‐Assisted Laser Desorption/Ionization—Time of Flight Mass Spectrometry (MALDI‐TOF MS) were applied on areas cleaned with the new formulations (IL + E) and reference areas cleaned only with the commercial enzyme formulations (gels). MALDI‐TOF proved particularly very useful for comparing the diversity and abundance of peptides released by using different enzymatic systems. Microsc. Res. Tech. 77:574–585, 2014. © 2014 Wiley Periodicals, Inc. 相似文献
47.
An architecture for the vlsi design of systems for time-frequency analysis and time-varying filtering 总被引:1,自引:1,他引:0
A flexible system for time-frequency signal analysis is presented. It is based on the S-method, which has a significant advantage in implementation since it can involve, as a key intermediate step, the Short-time Fourier transform or the Hartley transform, each widely studied and commonly used in practice. Signal invariant and signal dependent system forms are presented. Hardware design, for a fixed-point arithmetic, is well-structured and suitable for vlsi implementation. The same hardware, without additional time requirements, may be shared for the simultaneous realization of the fourth order L-Wigner distribution, as well as for the realization of the cross-terms free fourth order polynomial Wigner-Ville distribution. This possibility makes the designed hardware suitable for wide range of the applications. The proposed hardware is applied to the realization of time-varying filtering, as well. Finally, it has been implemented with fpga chips (Field Programmable Gate Array) in order to verify the results on real devices. 相似文献
48.
Hai-Hu Wen Henri A. Radovan Thomas Herzog Paul Ziemann 《Journal of Superconductivity and Novel Magnetism》1998,11(1):47-48
Investigations on flux dynamics of ring-shaped T12Ba2CaCu2O8 superconducting thin films have been carried out by measuring the temperature dependent magnetization M(T) during field-cooling (FC) and zero-field-cooling (ZFC) processes. For a given magnetic field, from the magnetization behavior two distinct temperatures, Tkink and Tirr, can be defined. Below Tkink, a clear hysteretic behavior of M(T) is observed leading to a large irreversible signal ΔM = MFC ? MZFC. Above Tkink, this irreversible signal, though being very small, is still non-zero until it eventually vanishes at a higher temperature Tirr. Above Tirr, both curves MFC(T) and MZFC(T) merge together and become temperature independent. We attribute the first region ( T< Tkink) to a 3D vortex-glass phase, the second region (Tkink < T < Tirr) to a vortex line liquid state and the third region (Tirr < T < Tc) to a pancake liquid state. 相似文献
49.
We measure the heat capacity of a UBe13 sample with an unusually low T
c for a polycrystal. We find an upturn in the upper critical field H
c2(T) below about T
c/2, much as for higher-T
c samples. Comparing the critical fields in our sample and in samples with higher T
c's shows that the low temperature limit of H
c2 is proportional to T
c(H = 0), as expected if the upturn comes from an FFLO phase and strong coupling. 相似文献
50.
This paper introduces two new concepts in peripheral cylindrical grinding of non-round workpieces: (1) choosing process parameters based on a thermal model for achieving a constant temperature; and (2) optimizing the grinding process for shorter cycle times while applying the concept of constant temperature. The modeling of geometry, kinematics and thermal aspects accounts for large variations in specific material-removal rate, contact length and workpiece velocity as the workpiece rotates. Optimization is validated both in simulation and with grinding experiments, including measurements of Barkhausen noise. Significantly reduced cycle times are obtained along with a better ability to avoid thermal damage. 相似文献