全文获取类型
收费全文 | 3217篇 |
免费 | 139篇 |
国内免费 | 35篇 |
专业分类
电工技术 | 52篇 |
综合类 | 59篇 |
化学工业 | 557篇 |
金属工艺 | 109篇 |
机械仪表 | 100篇 |
建筑科学 | 86篇 |
矿业工程 | 10篇 |
能源动力 | 146篇 |
轻工业 | 190篇 |
水利工程 | 15篇 |
石油天然气 | 15篇 |
武器工业 | 2篇 |
无线电 | 470篇 |
一般工业技术 | 706篇 |
冶金工业 | 401篇 |
原子能技术 | 15篇 |
自动化技术 | 458篇 |
出版年
2023年 | 23篇 |
2022年 | 54篇 |
2021年 | 71篇 |
2020年 | 39篇 |
2019年 | 43篇 |
2018年 | 52篇 |
2017年 | 58篇 |
2016年 | 66篇 |
2015年 | 50篇 |
2014年 | 90篇 |
2013年 | 244篇 |
2012年 | 176篇 |
2011年 | 184篇 |
2010年 | 149篇 |
2009年 | 173篇 |
2008年 | 150篇 |
2007年 | 139篇 |
2006年 | 152篇 |
2005年 | 113篇 |
2004年 | 98篇 |
2003年 | 81篇 |
2002年 | 72篇 |
2001年 | 69篇 |
2000年 | 69篇 |
1999年 | 74篇 |
1998年 | 112篇 |
1997年 | 101篇 |
1996年 | 116篇 |
1995年 | 70篇 |
1994年 | 63篇 |
1993年 | 51篇 |
1992年 | 45篇 |
1991年 | 36篇 |
1990年 | 33篇 |
1989年 | 39篇 |
1988年 | 36篇 |
1987年 | 25篇 |
1986年 | 30篇 |
1985年 | 16篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 15篇 |
1981年 | 19篇 |
1980年 | 9篇 |
1979年 | 12篇 |
1977年 | 12篇 |
1976年 | 15篇 |
1975年 | 5篇 |
1972年 | 6篇 |
1970年 | 2篇 |
排序方式: 共有3391条查询结果,搜索用时 15 毫秒
61.
A figure of merit (FOM) has been developed to define the quality of ceramic (e.g., ZrO2) coatings on metal and alloy [Type 304SS and Alloy 600] surfaces. Zirconia (ZrO2) coatings were developed as a means of protecting the metal/alloy surfaces from stress corrosion cracking (SCC) in boiling water reactor (BWR) primary heat transport circuits, by inhibiting the cathodic reaction (reduction of oxygen and hydrogen peroxide) on the surface external to the crack. The distribution of pores in the coating plays an important role in corrosion prevention, such that the lower the porosity of the coating, the better the protection afforded to the system against SCC. Since the reactors operate at high temperature (e.g., at 288 °C under full power conditions), the temperature dependence of the FOM was investigated. The figure of merit (FOM) was developed by measuring impedance data over a wide range of frequency (10 mHz-5 kHz) at temperatures of 25, 100, 200, and 288 °C in hydrogenated, buffered solutions, with the hydrogen electrode reaction (HER) being used as a “fast” redox couple. An “equivalent circuit” analog was first developed from the bare surface impedance data and this analog was then employed in a second step to model the pore bottom in defining the pore distribution on the coated surface. A lognormal distribution (LND) of the pores was assumed and the parameters of the LND were determined using a constrained optimization technique to fit the model to the experimental data for the coated surface at different temperatures. The results suggest that, as temperature increases, the coating becomes more porous, making the substrate more susceptible to corrosion cracking. At 288 °C, 87% of the SS and 85% of the Ni-alloy surfaces become porous with the pore radius varying from 0.0001 cm to 0.01 cm. 相似文献
62.
Shuang-Lin Chen Jie-Yu Zhang Xiong-Gang Lu Kuo-Chih Chou Y. Austin Chang 《Journal of Phase Equilibria and Diffusion》2006,27(2):121-125
Graham scan, a computational geometric algorithm for finding a two-dimensional convex hull, is introduced to calculate binary
phase diagrams. This algorithm is modified and applied to find the convex hull of discrete points in the space of Gibbs energy
vs mol fraction. The modified Graham scan algorithm has a very low computational cost, which improves efficiency in binary
phase diagram calculation. 相似文献
63.
64.
关于铁合金中相变的详尽显微组织方面的早期研究之一是由艾伯特·苏佛教授的学生周志宏(哈佛大学博士,1928年)完成的。该项研究描述了铁碳合金中魏氏组织和马氏体的形成,所用合金具有宽的碳含量范围,热处理时采用的冷却速率范围也是宽的。还描述了一种独特的汞浴淬火方法。此研究工作从未完全发表过。本文援引该博士论文中的一些原始显微组织照片和部分原文,并试图用我们现今对于铁合金相变的理解来阐明和重新诠释。文中还包括中国引进现代工业和科学的历史背景,以及周志宏对苏佛教授的个人回忆。 相似文献
65.
Kuo‐Chung Huang Yi‐Heng Chou Lang‐chin Lin Hoang Yan Lin Fu‐Hao Chen Ching‐Chiu Liao Yi‐Han Chen Kuen Lee Wan‐Hsuan Hsu 《Journal of the Society for Information Display》2013,21(6):263-270
The optimal viewing distance was proposed as a parameter for designing a parallax barrier 3D display. It can be designed based on simple geometric method and by considering the pitches of image display pixels and parallax barrier, or even including the aperture ratios of the image display pixels and parallax barrier. It can be analyzed by using ray tracing method. By considering the optical refraction index of the cover glass, the angular behavior of the system becomes more realistic; however, the geometric method is difficult to be used. We propose a revised method for estimating the view distance and angular behavior. In this paper, we have demonstrated a designated eye position (DEP) for each view and shown that multiple DEPs make a circular curve around the center of the display. We prove the new concept by comparing the optical ray tracing calculations and optical measurement. 相似文献
66.
67.
Yao-Jen Chang Li-Der Chou Frank Tsen-Yung Wang Shu-Fang Chen 《Personal and Ubiquitous Computing》2013,17(2):351-358
Difficulties in executing daily living tasks hamper the quality of life of many individuals with cognitive impairments who are otherwise physically mobile. With sufficient and appropriate support on the job, many people with developmental disabilities and cognitive impairments are capable of participating in the world of work to various levels. Kinect is used as assistive technology for individuals with cognitive impairments to achieve the goal of performing task steps independently. In a community-based rehabilitation program under the guidance of three job coaches, a task prompting system called Kinempt was designed to assist four participants involving pre-service food preparation training. The study assessed the effectiveness of Kinempt in terms of precision and recall. A follow-up comparative study then evaluated a baseline method and the system of least prompts against the Kinempt system. Results indicate that for participants with cognitive disabilities, acquisition of job skills may be facilitated by use of Kinempt in conjunction with operant conditioning strategies. Our findings suggest that the image recognition technology may be able to facilitate task prompts needed by people with cognitive impairments. Therefore, the system may be helpful for pre-service training while increasing independence in the process of community integration. 相似文献
68.
69.
In this paper, we propose a scheme to integrate independent component analysis (ICA) and neural networks for electrocardiogram (ECG) beat classification. The ICA is used to decompose ECG signals into weighted sum of basic components that are statistically mutual independent. The projections on these components, together with the RR interval, then constitute a feature vector for the following classifier. Two neural networks, including a probabilistic neural network (PNN) and a back-propagation neural network (BPNN), are employed as classifiers. ECG samples attributing to eight different beat types were sampled from the MIT-BIH arrhythmia database for experiments. The results show high classification accuracy of over 98% with either of the two classifiers. Between them, the PNN shows a slightly better performance than BPNN in terms of accuracy and robustness to the number of ICA-bases. The impressive results prove that the integration of independent component analysis and neural networks, especially PNN, is a promising scheme for the computer-aided diagnosis of heart diseases based on ECG. 相似文献
70.
Several goals such as improving road safety and increasing transport efficiency are being pursued in intelligent transportation systems (ITS). Wireless vehicular communication is one technology to achieve these goals. Conducting vehicular experiments on the roads is an approach to studying the effectiveness of wireless vehicular communication. However, such an approach is costly, hard-to-control (repeat), dangerous, and infeasible when many vehicles and people are involved in the field trial. In contrast, the simulation approach does not have these problems. It is a very useful approach and complements the field trial approach. This paper presents NCTUns, an open source integrated simulation platform, for wireless vehicular communication network researches. This tool tightly integrates network and traffic simulations and provides a fast feedback loop between them. Therefore, a simulated vehicle can quickly change its driving behavior such as moving speed and direction when it receives a message from the wireless vehicular communication network. This capability is required by several novel ITS applications such as active collision avoidance systems. In this paper, we present the design, implementation, validation, and performance of this tool. 相似文献