全文获取类型
收费全文 | 235篇 |
免费 | 3篇 |
专业分类
化学工业 | 21篇 |
金属工艺 | 17篇 |
机械仪表 | 3篇 |
建筑科学 | 5篇 |
能源动力 | 6篇 |
轻工业 | 7篇 |
水利工程 | 3篇 |
无线电 | 25篇 |
一般工业技术 | 54篇 |
冶金工业 | 58篇 |
原子能技术 | 9篇 |
自动化技术 | 30篇 |
出版年
2022年 | 1篇 |
2021年 | 4篇 |
2019年 | 6篇 |
2018年 | 10篇 |
2017年 | 3篇 |
2016年 | 8篇 |
2015年 | 5篇 |
2014年 | 2篇 |
2013年 | 14篇 |
2012年 | 6篇 |
2011年 | 8篇 |
2010年 | 11篇 |
2009年 | 10篇 |
2008年 | 9篇 |
2007年 | 10篇 |
2006年 | 10篇 |
2005年 | 5篇 |
2004年 | 5篇 |
2003年 | 5篇 |
2002年 | 1篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 7篇 |
1998年 | 12篇 |
1997年 | 7篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有238条查询结果,搜索用时 15 毫秒
1.
The deformation characteristics of artificially cemented calcareous soil subjected to undrained cyclic triaxial loading are investigated at different confining pressure and cyclic stress levels. The influence of cementation on the shear stiffness is investigated by comparing the behavior of cemented and uncemented soils with similar initial conditions. It is observed that the deviator stress and the deviatoric strain at yield reduced with increasing number of cycles for cemented sand due to progressive degradation of bond, which results in significant decrease in stiffness. On the other hand, a strain-hardening effect is observed in uncemented sand and this results in increasing yield stress and strain with progressive number of cycles. A linear relationship between degradation index and number of cycles is observed for cemented sand. This relationship has been synthesized in the form of an empirical equation by modifying a previously proposed equation for cohesive soils. This empirical equation was further used to evaluate the fatigue life of soils by adopting a failure criterion. 相似文献
2.
Application of model predictive control strategy based on fuzzy identification to an SP-100 space reactor 总被引:1,自引:0,他引:1
In this work, a model predictive control method combined with fuzzy identification, is applied to the design of the thermoelectric (TE) power control in the SP-100 space reactor. The future TE power is predicted by using the fuzzy model identified by a subtractive clustering method of a fast and robust algorithm. The objectives of the proposed fuzzy model predictive controller are to minimize both the difference between the predicted TE power and the desired power, and the variation of control drum angle that adjusts the control reactivity. Also, the objectives are subject to maximum and minimum control drum angle and maximum drum angle variation speed. The genetic algorithm that is effective in accomplishing multiple objectives is used to optimize the fuzzy model predictive controller. A lumped parameter simulation model of the SP-100 nuclear space reactor is used to verify the proposed controller. The results of numerical simulations to check the performance of the proposed controller show that the TE generator power level controlled by the proposed controller could track the target power level effectively, satisfying all control constraints. 相似文献
3.
D. Banerjee G. K. Lai G. S. Upadhyaya 《Journal of Materials Engineering and Performance》1995,4(5):563-572
For production of fine-grained and corrosion-resistant tungsten carbide (WC) based cemented carbides, addition of chromium
carbide (Cr33C2) in small amounts is standard practice. No systematic study, however, has been made of the effects of large additions (maximum
6 wt % ) of Cr3C2 as a substitute for tungsten carbide. This study focuses on the effect of hard-phase substitution by C3C2 in WC-1OCo cemented carbide. An attempt is also made to modify the binder metal cobalt by partial or complete substitution
of nickel. Specimens were prepared using the standard liquid-phase sintering process and were tested for sintered porosity,
mechanical properties, corrosion resistance, and microstructural parameters. Results confirm the findings of earlier workers
regarding grain refinement and improvement of mechanical properties upon the addition of small amounts (<2 wt%) of Cr3C2. Modification of the binder phase improves indentation fracture toughness and corrosion resistance. Addition of Cr3C2 independent of the binder type improves corrosion resistance. 相似文献
4.
An attempt was made to modify the band gap of CdS ( 2.4 eV) by preparing a mixed lattice with a low-band-gap material, PbS (0.3 eV), giving a new set of materials, Cd
x
Pb1–x
S. Band gaps as low as 1.9 eV were achieved with increasing x. The preparation of Cd
x
Pb1–x
S was carried out by chemical-bath deposition. Structural characterization studies using X-ray diffraction (XRD), energy dispersion analysis by X-rays (EDAX), and optical microscopy were performed. The optical-absorption studies used to find the band gap are also described. 相似文献
5.
D. Upadhyaya F. H. Froes J. F. Watts C. M. Ward-Close 《Journal of Materials Science》1995,30(15):3839-3846
Five different types of SiC fibre produced by chemical vapour deposition were analysed using Auger electron spectroscopy (AES), scanning electron microscopy (SEM) and X-ray (WDX) analysis. Fibres studied include SCS0, SCS6, Sigma SM1240 and two types of SiC fibres denoted SAM1 and SAM2, produced in the Commonwealth of Independent States (Ukraine, former USSR). Fibres were fracturedin situ in the Auger spectrometer. For each fibre, the oxygen, carbon and silicon yields were measured and qualitative assessment of oxygen was performed. Results suggest that the SCS0 fibre contains less oxygen than other SiC fibres. It was revealed that the SAM1 fibre (120 m diameter) has a duplex SiC and carbon coating deposited over a 20 m tungsten core prior to the main SiC deposition, to decouple mechanically the tungsten core from the main SiC deposition. 相似文献
6.
This paper explores a new approach for predicting software faults by means of NARX neural network. Also, a careful analysis has been carried out to determine the applicability of NARX network in software reliability. The validation of the proposed approach has been performed using two real software failure data sets. Comparison has been made with some existing parametric software reliability models as well as some neural network (Elman net and TDNN) based SRGM. The results computed shows that the proposed approach outperformed the other existing parametric and neural network based software reliability models with a reasonably good predictive accuracy. 相似文献
7.
Total radiation dose at geostationary orbit 总被引:1,自引:0,他引:1
Active semiconductor components in satellites are sensitive to accumulated ionization radiation dose. Radiation dose and shielding estimations for electronic components are usually carried out using NASA models of space radiation particle flux. Accurate measurement of accumulated dose during the life of a satellite is essential for optimizing radiation shielding design for electronic components. Dosimeters were designed using radiation sensitive field-effect transistors (RADFETs) and accumulated dose at geostationary orbit was measured. Radiation dose as measured by these dosimeters with spherical aluminum shields are presented and compared with NASA model doses. 相似文献
8.
Shambhu Prasad Suraj Nayak Vamshi Vijay Rajib Mall 《Innovations in Systems and Software Engineering》2016,12(4):263-278
Simulink and Stateflow (SL/SF) models are being widely used to design and develop embedded systems. Often the SL/SF models of embedded controllers turn out to be large and consist of many subsystems and hierarchies. When such a system is maintained, it becomes difficult to manually analyse the model to identify the impacted elements due to the existence of several explicit and implicit dependencies among the model elements. To automate the analysis of an SL/SF model, we propose a metamodel to capture various types of dependencies existing across the basic blocks. We have named this metamodel Simulink dependency graph (SLDG). We investigate the use of SLDG in change impact visualization and regression test selection. We have developed a prototype tool by implementing our approach for the aforementioned applications. 相似文献
9.
Sintering of 434£ ferritic stainless steel powder compacts containing 0-8 volume %cx-AI20 a (1 J.1m size) and 0-4 weight % phosphorus in the form of either FesP or Fe2P was carried out in the temperature range 1150°C-1300°C, and the resultant densification parameters, ultimate compressive strengths and hardnesses were measured. The results reveal that temperatures of 1150°C and 1200°C produced liquid-phase sintering when phosphorus was added in the form of FeaP. With Fe2P additions, a higher sintering temperature of 1300°C densified the composites, and an increase in the phosphorus content to 3% uniformly enhanced the sintered properties: The presence of Al20 a particles at an optimum level only improved the properties of the liquid-phase sintered composites. 相似文献
10.
Simultaneous removal of nitrate and arsenic from drinking water sources utilizing a fixed-bed bioreactor system 总被引:1,自引:0,他引:1
A novel bioreactor system, consisting of two biologically active carbon (BAC) reactors in series, was developed for the simultaneous removal of nitrate and arsenic from a synthetic groundwater supplemented with acetic acid. A mixed biofilm microbial community that developed on the BAC was capable of utilizing dissolved oxygen, nitrate, arsenate, and sulfate as the electron acceptors. Nitrate was removed from a concentration of approximately 50 mg/L in the influent to below the detection limit of 0.2 mg/L. Biologically generated sulfides resulted in the precipitation of the iron sulfides mackinawite and greigite, which concomitantly removed arsenic from an influent concentration of approximately 200 ug/L to below 20 ug/L through arsenic sulfide precipitation and surface precipitation on iron sulfides. This study showed for the first time that arsenic and nitrate can be simultaneously removed from drinking water sources utilizing a bioreactor system. 相似文献