全文获取类型
收费全文 | 522篇 |
免费 | 52篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 22篇 |
综合类 | 1篇 |
化学工业 | 140篇 |
金属工艺 | 10篇 |
机械仪表 | 23篇 |
建筑科学 | 17篇 |
能源动力 | 42篇 |
轻工业 | 65篇 |
水利工程 | 4篇 |
石油天然气 | 8篇 |
无线电 | 49篇 |
一般工业技术 | 72篇 |
冶金工业 | 35篇 |
原子能技术 | 4篇 |
自动化技术 | 86篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2022年 | 14篇 |
2021年 | 27篇 |
2020年 | 21篇 |
2019年 | 34篇 |
2018年 | 46篇 |
2017年 | 38篇 |
2016年 | 35篇 |
2015年 | 26篇 |
2014年 | 27篇 |
2013年 | 51篇 |
2012年 | 41篇 |
2011年 | 38篇 |
2010年 | 17篇 |
2009年 | 23篇 |
2008年 | 14篇 |
2007年 | 21篇 |
2006年 | 10篇 |
2005年 | 4篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 10篇 |
1997年 | 7篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1974年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有578条查询结果,搜索用时 15 毫秒
1.
2.
Hussain Sheikha Anil K. Mehrotra Mehran Pooladi-Darvish 《Journal of Petroleum Science and Engineering》2006,53(3-4):189-202
An inverse solution methodology is developed for the estimation of diffusion coefficient of gases in highly viscous, oil-sands bitumens from isothermal, pressure-decay measurements. The approach involves modeling the rate of change in pressure using the diffusion equation for the liquid phase coupled with a mass balance equation for the gas phase. The inverse solution framework is utilized to arrive at two graphical techniques for estimating the diffusion coefficient. Both techniques involve the determination of the slope of a straight line resulting from plotting the experimental data in accordance with the developed model. An advantage of the proposed techniques is that the diffusion coefficient is estimated directly, i.e. without making it an adjustable parameter. The novelty of the proposed method is in its simplicity as well as its ability to isolate portions of the pressure-decay data affected by experimental fluctuations. The effect of the initial pressure on the predicted diffusion coefficient and pressure-decay profile was also investigated. The diffusion coefficients of CO2, CH4, C2H6 and N2 in Athabasca bitumen at 50–90 °C and about 8 MPa were estimated and compared with literature values. 相似文献
3.
4.
Multibody System Dynamics - Heretofore, the Serret–Frenet frame has been the ubiquitous choice for analyzing the elastic deformations of beam elements. It is well-known that this frame is... 相似文献
5.
Anas El Husseini Abdallah M’Hamed Bachar El Hassan Mounir Mokhtari 《Personal and Ubiquitous Computing》2013,17(5):1013-1023
In smart environments, pervasive computing contributes in improving daily life activities for dependent people by providing personalized services. Nevertheless, those environments do not guarantee a satisfactory level for protecting the user privacy and ensuring the trust between communicating entities. In this study, we propose a trust evaluation model based on user past and present behavior. This model is associated with a lightweight authentication key agreement protocol (Elliptic Curve-based Simple Authentication Key Agreement). The aim is to enable the communicating entities to establish a level of trust and then succeed in a mutual authentication using a scheme suitable for low-resource devices in smart environments. An innovation in our trust model is that it uses an accurate approach to calculate trust in different situations and includes a human-based feature for trust feedback, which is user rating. Finally, we tested and implemented our scheme on Android mobile phones in a smart environment dedicated for handicapped people. 相似文献
6.
A novel voltammetric sensor based on chemically modified bentonite–porphyrin carbon paste electrode (MBPCE) has been introduced for the determination of trace amount of Mn(II) in wheat flour, wheat rice and vegetables. In this method Mn(II) gives well-defined voltammetric peak at the pH range of 3.5–7.5. For the preliminary screening purpose, the catalyst was prepared by modification of bentonite with porphyrin and characterized by thermogravimetric method (TG) and UV–vis spectroscopy. The detection limit (three times signal-to-noise) with 4 min accumulation is 1.07 × 10−7 mol L−1 Mn(II). The peak currents increases linearly with Mn(II) concentration over the range of 6.0 × 10−7 to 5.0 × 10−4 mol L−1 (r2 = 0.9959). Statistical treatment of the results gave a relative standard deviation lower than 2.30%. The chemical and instrumental parameters have been optimized and the results showed that 1000-fold excess of the additive ions had not interferences on the determination of Mn(II). 相似文献
7.
8.
Huda Al Amri Author Vitae Mehran Abolhasan Author Vitae 《Computers & Electrical Engineering》2010,36(4):752-765
In Mobile Ad hoc Network (MANET), mobility, traffic and node density are main network conditions that significantly affect performance of routing protocols. Much of the previous research in MANET routing have focused on developing strategies, which suit one specific networking scenario. Therefore, there is no existing protocol that can work well in all different networking scenarios. This paper reviews characteristics of several different classes of routing protocols. Moreover, most of current routing protocols assume homogeneous networking conditions where all nodes have the same capabilities and resources. This paper presents extensive studies simulations for DSR, AODV, LAR1, FSR and WRP in homogenous and heterogeneous networks that consist of different nodes with different resources. The results showed that while all protocols perform reasonably well in homogenous networking conditions, their performance suffer significantly over heterogonous networks. 相似文献
9.
Skin detection is a difficult and primary task in many image processing applications. Because of the diversity of various
image processing tasks, there exists no optimum method that can perform properly for all applications. In this paper, we have
proposed a novel skin detection algorithm that combines color and texture information of skin with cellular learning automata
to detect skin-like regions in color images. Skin color regions are first detected, by using a committee structure, from among
several explicit boundary skin models. Detected skin-color regions are then fed to a texture analyzer which extracts texture
features via their color statistical properties and maps them to a skin probability map. This map is then used by cellular
learning automata to adaptively make a decision on skin regions. Conducted experiments show that the proposed algorithm achieves
the true positive rate of about 86.3% and the false positive rate of about 9.2% on Compaq skin database which shows its efficiency. 相似文献
10.