全文获取类型
收费全文 | 115篇 |
免费 | 5篇 |
专业分类
化学工业 | 29篇 |
金属工艺 | 1篇 |
机械仪表 | 3篇 |
建筑科学 | 2篇 |
能源动力 | 9篇 |
轻工业 | 15篇 |
石油天然气 | 5篇 |
无线电 | 15篇 |
一般工业技术 | 22篇 |
冶金工业 | 5篇 |
原子能技术 | 1篇 |
自动化技术 | 13篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 1篇 |
2018年 | 14篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 4篇 |
2014年 | 6篇 |
2013年 | 18篇 |
2012年 | 6篇 |
2011年 | 4篇 |
2010年 | 7篇 |
2009年 | 5篇 |
2008年 | 4篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2003年 | 2篇 |
2002年 | 3篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
排序方式: 共有120条查询结果,搜索用时 3 毫秒
1.
This paper proposes and investigates a novel analytical model of a hybrid channel allocation algorithm within wireless cellular networks. Each cell of the network consists of a predesigned fixed number of channels and the network may approve the request for extra channels for both new and handoff calls if all predesigned channels are occupied. This approval depends on the types of new and handoff calls, as well as the number of approved additional channels in the cell. If a request is denied for the arriving new call, this call will be blocked and cleared from the system. However, if a request is denied for an arriving handoff call, this call will not be blocked immediately but rather put on hold in a buffer with finite space. The implication behind this is to give priority to handoff calls. For this proposed hybrid channel allocation scheme, we first obtain the stationary distribution of each cell when there are i calls connecting to the system and j calls holding on in the buffer. We then derive new and handoff call blocking probabilities, the average number of borrowed channels, and the average delay period of handoff calls. The numerical results show that the proposed hybrid algorithm is more efficient than other approaches, specifically, in comparison with methods without a borrowing capability for new calls and those without a reserved buffer priority for handoff calls. The idea and results presented in this paper are expected to provide guidelines for field data processing within current wireless and mobile network design and performance evaluation. 相似文献
2.
Zargham Salari 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2016,38(4):549-554
One of the main factors in chemical-based enhanced oil recovery, especially surfactant flooding, is a surfactant adsorption loss onto the reservoir rock. The main aim of this article is performing systematically a study on the adsorption behavior of an industrial ionic surfactant, which is currently employed in petroleum upstream. It is worth mentioning that sodium dodecyle sulphate was employed as an ionic surfactant in this study. Moreover, adsorption density at equilibrium condition was determined. Crushed carbonate rocks were used as rock samples. To determine adsorption behavior of the aforementioned surfactant onto carbonate surface, various surfactant concentrations were created in the range of 500 to 5,000 ppm. Furthermore, via using an electrical conductivity measurement, the surfactant concentration in each solution before and after contacting with carbonate rocks was determined. Two well-known adsorption isotherms, including Freundlich and Langmuir, were employed to specify the adsorption mechanism. Based on the experimental results the Freundlich adsorption isotherm can predict the adsorption behavior of SDS onto carbonate rock surface. 相似文献
3.
4.
Numerical investigation of the effects of geometric parameters of heaters on mixed covection in a lid‐driven cavity filled with different nanofluids 下载免费PDF全文
In this paper, the effects of the thicknesses and locations of two rectangular heaters, located on the bottom and one side of on an enclosure, on mixed convection of nanofluid flows in a lid‐driven cavity are numerically investigated. The enclosure is simultaneously heated partially by these two heaters which have similar or different thicknesses and also filled with different nanofluids containing nanoparticles of Cu, Ag, Al2O3, and TiO2 within the base fluid of water. A finite volume approach by the SIMPLE algorithm is used to solve the governing equations. The effects of different Rayleigh numbers (), Reynolds numbers (), solid volume fractions (), heater lengths (), heater locations () and heater thicknesses () on the streamlines, isotherms and the average Nusselt number along two heaters are studied accurately. Also, variations of average Nusselt number of two heaters are considered whenever one heater is fixed and the other heater moves along on the wall. Moreover, variations of the length of one heater on the average Nusselt number are also studied whenever the length of the other heater is fixed. In addition, variations of the thickness of one heater on the average Nusselt number are studied whenever the thickness of the other heater is fixed. 相似文献
5.
It is well known that at low bit rates, a block-based discrete cosine transform compressed image or video can exhibit visually annoying blocking and ringing artifacts. Low-pass filters are very effective in reducing the blocking artifacts in smooth areas. However, it is difficult to achieve a satisfactory result for ringing artifact removal using only an adaptive filtering scheme. This paper presents a neural network-based deblocking method that is effective on various types of images. The first step of this scheme is block classification that identifies each 8 × 8 block as one of the three types: PLAIN, EDGE or TEXTURE, based on its statistical characteristics. The next step is the reduction in the blocking and ringing artifacts by applying three trained layered neural networks to three different types of image areas. Comparing this method with other algorithms, the simulation results clearly show that the proposed algorithm is very powerful in effectively reducing both blocking and ringing artifacts while preserving the true edge and textural information and thus significantly improving the visual quality of the blocking images or videos. 相似文献
6.
Iron‐oxide nanoparticles (IONPs) have been widely favoured due to their biodegradable, low cytotoxic effects and having reactive surface which can be altered with biocompatible coatings. Considering various medical applications of IONPs, the authors were encouraged to study whether IONPs could be effective against fungal infections caused by Candida species. In this study, IONPs were characterised by scanning electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy and vibrating sample magnetometer. The goal of this study was to evaluate the antifungal activity of IONPs against different Candida spp. compared with fluconazole (FLC). IONPs were spherical with the size of 30–40 nm. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values of IONPs ranged from 62.5 to 500 µg/ml and 500 to 1000 μg/ml, respectively. The MIC and MFC of FLC were in range of 16–128 μg/ml and 64–512 μg/ml, respectively. The growth inhibition value indicated that Candida tropicalis, Candida albicans and Candida glabrata spp. were most susceptible to IONPs. The finding showed that the IONPs possessed antifungal potential against pathogenic Candida spp. and could inhibit the growth of all the tested Candida spp. Further studies, both in vitro and in vivo (including susceptibility, toxicity, Probability of kill (PK) and efficacy studies) are needed to determine whether IONPs are suitable for medicinal purposes.Inspec keywords: iron compounds, nanoparticles, nanomedicine, biomedical materials, microorganisms, cellular biophysics, toxicology, drugs, scanning electron microscopy, X‐ray diffraction, Fourier transform infrared spectraOther keywords: antifungal effect, iron‐oxide nanoparticles, Candida species, biodegradable effects, cytotoxic effects, reactive surface, biocompatible coatings, medical applications, IONP, fungal infections, Candidiasis, immunocompromised hosts, antifungal drugs, resistant organisms, antifungal properties, side effects, chemical drugs, scanning electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, vibrating sample magnetometer, antifungal activity, disc diffusion, broth microdilution, minimal inhibitory concentration, minimum fungicidal concentration, Candida tropicalis, Candida Albicans, Candida glabrata, antifungal potential, Fe3 O4 相似文献
7.
8.
Mina Martini Iolanda Altomonte Rossana Pesi Maria Grazia Tozzi Federica Salari 《International Dairy Journal》2013,28(1):36-39
A trial was carried out on seven Massese ewes, from which individual milk samples were taken during lactation. All the enzyme activities investigated (oxidase activity of xanthine oxidoreductase, gamma-glutamyltranspeptidase, alkaline phosphatase and 5′-nucleotidase) were affected by the lactation phase, with the exception of the dehydrogenase activity of xanthine oxidoreductase (XOR). A higher oxidase activity (XO) of XOR was found when the diameter of milk fat globules was smaller. In addition, the absence of XO in colostrum led to the hypothesis that its antibacterial role is independent of its activity. The increase in alkaline phosphatase activity during lactation requires further research to better define the criteria for pasteurised sheep milk. 相似文献
9.
This paper describes a novel speech analysis application which was implemented using a Motorola M68HC11 microcontroller system. This microcontroller-based platform was designed to function as a pitch extractor for voiced speech in real time. In this context, pitch extraction is the identification of individual pitch periods, or glottal cycles, from a raw speech waveform. The system implements a new pitch determination algorithm (PDA) that is based on a progressing wave model of speech generation. The PDA was developed specifically to operate in real-time and to maintain phase characteristics with the raw speech signal. As one possible application, the pitch extractor was incorporated into a dual processor system designed to function as a Musical Instrument Digital Interface (MIDI)-compatible controller. 相似文献
10.
The authors present a classified vector quantiser (CVQ) based on Peano scanning. The Peano scanning, which is used to reduce the dimensionality of the data, provides a one-dimensional algorithm to classify an image block. The class of the block is determined based on its Peano scanning value from a look up table (LUT) of representative Peano scanning values and their associated classes. The Peano scanning algorithm is easily implemented in hardware, and the class can be determined in a logarithmic time proportional to the number of entries in the LUT when using a binary search algorithm on the sorted version of the LUT. Moreover, the class lookup table is easily implemented in real time. An effective algorithm is used to generate all the codebooks of the classes simultaneously in a systematic way by growing a greedy tree for each class in an interconnected way. The monochromatic images encoded in the range of 0.625~0.813 bits/pixel, with a 16-dimensional vector size, are shown to preserve the edge integrity and quality as determined by subjective and objective measures 相似文献