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A digital recording system is modeled by means of a complex Fourier series representation employing transforms of arctangent functions to describe the effects of write field gradient demagnetization and self-demagnetization. Pulse asymmetry and rise time effects are incorporated by means of phase shifts from complex transfer functions used in describing the dependence of head properties on a complex permeability. Experimental measurements on a specific system (Co substituted γ-Fe2 O3 tape and metal heads) show good correlation with the theory, especially with respect to spectral content, waveform shape, and peak shifts. The model is one-dimensional and limited to recording media initially ac demagnetized and to a write current range in which it is possible to define an effective penetration depth for saturation recording. 相似文献
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A theoretical-experimental study of tandem-junction, front-surface-field, and interdigitated-back-contact solar cells is presented. The approach taken in the theoretical analysis emphasizes detailed qualitative physical reasoning which leads to quantitative results. This approach enables the three-dimensional boundary-value problems describing these solar cells to be made tractable. A major result is a unifying view of the physics underlying the performance of these cells. The important physical mechanisms are identified and described, and cell design considerations and trade-offs are discussed. 相似文献
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The Fourier transforms of the three field components of a finite width reproducing head are derived and given in analytic forms. These formulas represent three-dimensional analogs of the familiar two-dimensional exponential spacing loss factor. The on- and off-track head response to a longitudinally magnetized track is computed from these results and compared with experimental measurements on registration loss and read crosstalk. As long as the head-to-medium separation and medium thickness are small compared to the head width, the results are in relatively simple analytic forms. 相似文献
46.
Review of translocations detected by FISH for retrospective biological dosimetry applications 总被引:2,自引:0,他引:2
Edwards AA Lindholm C Darroudi F Stephan G Romm H Barquinero J Barrios L Caballin MR Roy L Whitehouse CA Tawn EJ Moquet J Lloyd DC Voisin P 《Radiation protection dosimetry》2005,113(4):396-402
Several European laboratories have combined their research efforts to arrive at a consensus view on using fluorescence in situ hybridisation (FISH) for retrospective dosimetry. The aim of this review is to report these views and to highlight some areas where further work is needed. Translocations in the stable cells should be measured only in the cells that contain the full complement of the painted material. Two-way and one-way translocations should be combined with equal weight. The control level of translocations has a strong dependence on age, which has now been measured and the system has been calibrated. In conclusion, the technique works and a lifetime dose to the bone marrow from low-linear energy transfer radiation of 0.5 Gy above normal background levels can be measured for any individual. The main application is considered to provide an independent verification of lifetime doses to individuals who might form a part of an epidemiological study. 相似文献
47.
Engineers and researchers working on the development of airborne wind energy systems (AWES) still rely on oversimplified wind speed approximations and coarsely sampled reanalysis data because of a lack of high‐resolution wind data at altitudes above 200 m. Ten‐minute average wind speed LiDAR measurements up to an altitude of 1100 m and data from nearby weather stations were investigated with regard to wind energy generation and impact on LiDAR measurements. Data were gathered by a long‐range pulsed Doppler LiDAR device installed on flat terrain. Because of the low overall carrier‐to‐noise ratio, a custom‐filtering technique was applied. Our analyses show that diurnal variation and atmospheric stability significantly affect wind conditions aloft which cause a wide range of wind speeds and a multimodal probability distribution that cannot be represented by a simple Weibull distribution fit. A better representation of the actual wind conditions can be achieved by fitting Weibull distributions separately to stable and unstable conditions. Splitting and clustering the data by simulated surface heat flux reveals substate stratification responsible for the multimodality. We classify different wind conditions based on these substates, which result in different wind energy potential. We assess optimal traction power and optimal operating altitudes statistically as well as for specific days based on a simplified AWES model. Using measured wind speed standard deviation, we estimate average turbulence intensity and show its variation with altitude and time. Selected short‐term data sets illustrate temporal changes in wind conditions and atmospheric stratification with a high temporal and vertical resolution. 相似文献
48.
Nicki Frederiksen Assoc. Prof. Paul R. Hansen Dr. Dorota Zabicka Magdalena Tomczak Malgorzata Urbas Dr. Ilona Domraceva Prof. Fredrik Björkling Assoc. Prof. Henrik Franzyk 《ChemMedChem》2020,15(24):2544-2561
The influence of hydrophobicity on antibacterial activity versus the effect on the viability of mammalian cells for peptide/peptoid hybrids was examined for oligomers based on the cationic Lys-like peptoid residue combined with each of 28 hydrophobic amino acids in an alternating sequence. Their relative hydrophobicity was correlated to activity against both Gram-negative and Gram-positive species, human red blood cells, and HepG2 cells. This identified hydrophobic side chains that confer potent antibacterial activity (e. g., MICs of 2–8 μg/mL against E. coli) and low toxicity toward mammalian cells (<10 % hemolysis at 400 μg/mL and IC50>800 μg/mL for HepG2 viability). Most peptidomimetics retained activity against drug-resistant strains. These findings corroborate the hypothesis that for related peptidomimetics two hydrophobicity thresholds may be identified: i) it should exceed a certain level in order to confer antibacterial activity, and ii) there is an upper limit, beyond which cell selectivity is lost. It is envisioned that once identified for a given subclass of peptide-like antibacterials such thresholds can guide further optimisation. 相似文献
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Ilona Bella Tio Putra Wendari Novesar Jamarun Nandang Mufti 《Ceramics International》2021,47(6):8014-8019
In this study, a hydrothermal method was applied to synthesize the three-layer Aurivillius phase Sr2Bi2Ta2TiO12 (SBTTO) and Mn-substituted Sr1·5Bi2·5Ta2Ti0·5Mn0·5O12 (SBTTMO), with the use of NaOH as a mineralizer. The crystal structure, morphology, dielectric properties, and the correlation between the structural transformation and dielectric properties were investigated. The XRD data reveal that the SBTTO sample adopts a tetragonal crystal structure with the I4/mmm space group and is then transformed into an orthorhombic structure with the B2cb space group for SBTTMO. The morphology of both samples was observed by SEM, which showed anisotropic plate-like grains. With the Mn substitution, the ferroelectric transition temperature (Tc) significantly increases as the influence of the 6s2 lone pair of Bi3+ increases, and this in turn further induces the relaxor-ferroelectric behavior. Consequently, the increase in Tc confirms the structural transformation from the paraelectric-tetragonal to the ferroelectric-orthorhombic phase. 相似文献