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排序方式: 共有152条查询结果,搜索用时 31 毫秒
1.
In this paper, we consider the classical finite mixture model, which is an effective tool for modeling lifetime distributions for random samples from heterogeneous populations. We discuss new results on stochastic comparison for two finite mixtures when each of them is drawn from one of the following semiparametric families, i.e., proportional hazards, accelerated lifetime and proportional reversed hazards. 相似文献
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Porous titanium dioxide (Titania) thin films were grown by anodic oxidation using high purity (99.7%) titanium foil in a dilute sulphuric acid (1 M) medium. The anodization process was carried out for 30 minutes with 20 mA/cm2 and 50 mA/cm2 current densities. The samples were characterized by XRD, SEM, and AFM techniques. It was found that the grown porous titania films were less sensitive to 500 ppm hydrogen in air ambient below 300°C; however, the sensitivity and response behavior of the film at 300°C are very much dependent on the growth conditions. Particularly, the films grown at current density 50 mA/cm2 and 1 M acid concentration exhibited the lowest response time of 151 sec at 300°C. 相似文献
4.
Telecommunication Systems - Device-to-device (D2D) communication enabled cellular system is capable of enhancing the spectrum utilization and throughput performance of the system. However, D2D... 相似文献
5.
Atindra Mohan Bandyopadhyay Aritra Acharyya J. P. Banerjee 《Journal of Computational Electronics》2014,13(3):769-777
A large-signal method based on non-sinusoidal voltage excitation model is used to study the DC and RF characteristics of Double Avalanche Region (DAR) Silicon Transit Time diode. A large-signal simulation program based on drift-diffusion model is developed for this study. The simulation results show the existence of several distinct negative conductance bands in the admittance characteristics separated by positive conductance. Thus the DAR device is capable of delivering RF power not only at the design frequency but also at several frequency bands higher than the design frequency band in the mm-wave regime. A comparative study with DDR Si device designed to deliver RF power at a particular mm-wave frequency band shows that DAR Si device is capable of delivering significantly higher RF power not only at the designed mm-wave frequency band, but also at higher frequency bands. 相似文献
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Mingdi Jiang Aritra Nath Chattopadhyay Vincent M. Rotello 《International journal of molecular sciences》2022,23(7)
Synthetic chemicals are widely used in food, agriculture, and medicine, making chemical safety assessments necessary for environmental exposure. In addition, the rapid determination of chemical drug efficacy and safety is a key step in therapeutic discoveries. Cell-based screening methods are non-invasive as compared with animal studies. Cellular phenotypic changes can also provide more sensitive indicators of chemical effects than conventional cell viability. Array-based cell sensors can be engineered to maximize sensitivity to changes in cell phenotypes, lowering the threshold for detecting cellular responses under external stimuli. Overall, array-based sensing can provide a robust strategy for both cell-based chemical risk assessments and therapeutics discovery. 相似文献
8.
Multiwalled carbon nanotubes were irradiated with ultra-low energy (few eV) nitrogen and hydrogen ions using a microwave discharge. These ultra-low energy plasma-ions remain confined to the nanotube walls, transferring their maximum energy to the carbon atoms, and produce extraordinary structural changes to the carbon nanotube pillars as well as within the carbon nanotubes. Conical shaped emitters and nanotube structures with nano-defects are produced that exhibit remarkable field emission with ultra-low turn-on electric field (∼0.16 V/μm) and a >300-fold increase in the maximum emission current density compared to non-irradiated nanotubes. Doping of nitrogen is also identified due to such irradiation processes. 相似文献
9.
This paper presents an implementation of a genetic algorithm in the structural design of broken contact doublets according to a prespecified set of Gaussian characteristics and primary aberration targets. The objective of this study is to investigate the effectiveness of the algorithm in finding out global as well as useful local optima and its dependence on some parameters characterizing the genetic operators. Actual glasses are taken as variables. Some illustrative examples are given. 相似文献
10.
Alok K. Hazra Somiranjan Ghosh Shivaji Banerjee Biswapati Mukherjee 《Journal of the American Oil Chemists' Society》1998,75(11):1673-1678
The puffer fishes Chelonodon patoca, Sphaeroides oblongus, Lagocephalus lunaris, and L. inermis of Indian coastal waters are wasted in huge quantity. The livers of these fishes were investigated for their lipid contents
and fatty acid compositions in different seasons. It was found that monsoon season is the suitable time to obtain the maximal
lipids (40.1–48.8%) from their livers, an amount similar to cod liver lipid content (39.5–55.0%). The fatty acids were mostly
saturates and monoenes (60–70%). Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) concentrations (7–12%) were high
during monsoon season. Neutral lipids were the predominant lipid class (>80%) and comprised triglycerides (277–674 mg/g) and
cholesterol (0.6–3.1 mg/g). Quality indices of puffer liver lipids, e.g., specific gravity, refractive index, acid value,
iodine value, saponification value and unsaponifiable matter, were evaluated. Puffer liver lipids were quantitatively and
qualitatively comparable to other commercially important marine fish oils. The overall study suggests the possibility of future
commercial utilization of liver lipids from puffer, an unconventional, cheap, and easily available source. 相似文献