全文获取类型
收费全文 | 463篇 |
免费 | 18篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 22篇 |
综合类 | 1篇 |
化学工业 | 69篇 |
金属工艺 | 14篇 |
机械仪表 | 17篇 |
建筑科学 | 38篇 |
能源动力 | 31篇 |
轻工业 | 22篇 |
水利工程 | 2篇 |
石油天然气 | 10篇 |
无线电 | 60篇 |
一般工业技术 | 66篇 |
冶金工业 | 49篇 |
自动化技术 | 82篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 22篇 |
2021年 | 32篇 |
2020年 | 20篇 |
2019年 | 16篇 |
2018年 | 23篇 |
2017年 | 24篇 |
2016年 | 27篇 |
2015年 | 12篇 |
2014年 | 14篇 |
2013年 | 43篇 |
2012年 | 9篇 |
2011年 | 28篇 |
2010年 | 20篇 |
2009年 | 18篇 |
2008年 | 14篇 |
2007年 | 14篇 |
2006年 | 11篇 |
2005年 | 7篇 |
2004年 | 11篇 |
2003年 | 11篇 |
2002年 | 6篇 |
2001年 | 7篇 |
2000年 | 5篇 |
1999年 | 9篇 |
1998年 | 3篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 9篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有483条查询结果,搜索用时 640 毫秒
1.
2.
Nassar Sabry S. Faragallah Osama S. El-Bendary Mohsen A. M. 《Wireless Personal Communications》2021,119(1):37-61
Wireless Personal Communications - Due to the widely spreading of fake news utilizing image manipulation and its bad effects, this paper investigates efficient image contents verification and... 相似文献
3.
4.
Osama Y. Abudayyeh 《Advances in Engineering Software》1993,16(3):187-193
Effective management of construction projects depends on good access to and control of data, especially data pertaining to cost and schedule control functions. However, the proper design and development of automated mechanisms have not had the facility to acquire and store quality data in a timely manner. The purpose of this paper, then, is to discuss a prototype, automated data acquisition system that was developed to support an integrated project management system. The data acquisition system is composed of an integrated set of electronic forms used in conjunction with a bar coding data-entry tool. 相似文献
5.
Four oil families are identified in the southern Gulf of Suez, through high-resolution geochemical studies including gas chromatography, gas chromatography-mass spectrometry, and carbon isotope analyses. Biological features characterize oils in family 1a, suggesting tertiary carbonate source rocks for these oils, rich in type II organic matter and deposited under anoxic depositional environment. Family 1b oil shows minor variations in the source of organic matter and the depositional environment, as it was derived from carbonate source rock with more algal and bacterial contribution and minor input of terrestrial organic sources, deposited under less saline condition compared to family 1a oil. Family 2 oil, although genetically related to family 1a oil, has some distinctive features, such as diasterane to sterane and pristane to phytane ratios, which suggest clay-rich source rocks and a more oxic depositional environment. Also, the lack of oleanane indicates pre-tertiary source rocks for this oil. In contrast, family 3 oil is of mixed sources (marine and non-marine), generated from low sulfur and clay-rich source rock of tertiary and/or younger age. Family 4 oil seems to be mixed from family 1b and family 3 oils, sourced mainly from carbonate source rocks rich in clay minerals with algal and bacterial contributions. Family 4 oil is highly mature, family 1b oil lies within equilibrium values (peak oil generation stage), while the other families are more or less near equilibrium. 相似文献
6.
Ahmed Helmy Khaled Sharaf Hani Ragai 《Analog Integrated Circuits and Signal Processing》2003,37(3):139-148
A noise analysis of bipolar harmonic mixers (BHM) used for direct-conversion receivers is presented in this paper. Analytical and simulated results for the transfer function of the mixer are presented. Simple analytical expressions describing noise contribution from all sources are derived. Estimation of flicker noise quite agrees with harmonic-balance simulation results. Based on the derived expressions, total time average noise power spectral density (PSD) at the output is compared with simulation results. For the recommended regions of operation, error is less than 20%. The overall BHM noise figure (NF) is calculated and optimized based on a simple extracted formula. Errors introduced by analysis remain within a 1.5-dB margin with respect to simulation results. The validity of analysis for high frequencies is justified. The effect of flicker noise coefficient on the overall mixer NF is compared for different available processes. 相似文献
7.
This study is concerned with the assessment of risk for major construction activities. Risk has been defined as a measure of the probability, the severity, and the exposure of all hazards of an activity. A risk assessor model (RAM) was developed and computerized to determine the risk associated with a particular activity and the justification factor for a proposed remedy. Knowing the value of risk would help contractors identify the high risk of major construction activities and would enable them to allocate safety precautions in a more efficient manner. 相似文献
8.
Jin B. Ong Osama K. Eyada PhD PE Abu S. Masud PhD PE 《Computers & Industrial Engineering》1989,17(1-4):85-89
This paper presents a Knowledge-based system (KBS) developed to allow users, who may not be knowledgeable about sensors, to select sensors suitable for their specific needs. The KBS runs on a micro-computer. The selection criteria are user specified and are based on the desired measurement parameters. The system output includes all of the operational and dimensional parameters of the recommended sensor, price, and vendor information. 相似文献
9.
Saye D. S. Abd El Rehim Soad M. Abd El Wahaab Osama M. Abdella 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1985,35(5):217-222
The electroplating of Ni-Cd alloy coatings was carried out from alkaline baths (pH 10). For comparison, electroplating of the parent metals, Ni and Cd, was performed individually under the same conditions. The cathodic current efficiency for codeposition was high and decreased with increasing current density. The codeposition process is an anomalous type of plating with Cd being the preferentially deposited metal. The Ni content in the deposits increased with increasing current density. This increase in Ni content improves the corrosion resistance and microhardness of the deposits. X-ray diffraction analysis showed that the deposits consist of a mixture of Ni, β, γ, γ1 phases. 相似文献
10.
The field experiment was conducted to study the effect of various levels of chlormequat (CCC) and alar on the biochemical changes in tomato plants and fruits at different stages of growth. This experiment included spraying with chlormequat and alar separately in two equal doses (250, 500 and 1000 ppm CCC or alar 25 and 40 days after transplanting). The different levels of chlormequat decreased the accumulation of dry matter in tomato plants, but alar increased it. Chlorophyll a, b, total chlorophyll and carotenoids content of tomato plants increased by the application of CCC or alar. The highest increase of concentration of chlorophyll a, b and carotenoids in tomato plants were found by spraying with 500 ppm alar or CCC. The application of CCC and alar declined the percentage of carbohydrates and the highest decrease resulted by adding of 1000 ppm alar or CCC. Alar caused an increase in the percentage of total nitrogen at the different stages of growth. The concentration of P, K, Ca and Mg increased by the foliar spray of all treatments. Alar application at all used levels significantly increased the yield and also the weight of fruits. Highest plant productivity was obtained by using alar and CCC at 250 ppm, followed by 500 ppm. However, the highest concentration (1000 ppm) depressed the plant productivity. The concentration of juice, total soluble solids and vitamin C in tomato fruits increased at most of the levels added. But the percentage of total sugars and total acidity seemed to exert another trend. The highest concentration of N, P, K, Ca and Mg in fruits was obtained by foliar application of 500 ppm CCC or alar. 相似文献