全文获取类型
收费全文 | 1712篇 |
免费 | 135篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 32篇 |
综合类 | 3篇 |
化学工业 | 328篇 |
金属工艺 | 12篇 |
机械仪表 | 58篇 |
建筑科学 | 69篇 |
能源动力 | 67篇 |
轻工业 | 142篇 |
水利工程 | 12篇 |
石油天然气 | 13篇 |
无线电 | 328篇 |
一般工业技术 | 331篇 |
冶金工业 | 126篇 |
原子能技术 | 2篇 |
自动化技术 | 333篇 |
出版年
2023年 | 11篇 |
2022年 | 30篇 |
2021年 | 64篇 |
2020年 | 42篇 |
2019年 | 43篇 |
2018年 | 68篇 |
2017年 | 52篇 |
2016年 | 65篇 |
2015年 | 42篇 |
2014年 | 63篇 |
2013年 | 124篇 |
2012年 | 68篇 |
2011年 | 94篇 |
2010年 | 85篇 |
2009年 | 98篇 |
2008年 | 100篇 |
2007年 | 73篇 |
2006年 | 76篇 |
2005年 | 71篇 |
2004年 | 60篇 |
2003年 | 68篇 |
2002年 | 41篇 |
2001年 | 39篇 |
2000年 | 38篇 |
1999年 | 43篇 |
1998年 | 58篇 |
1997年 | 37篇 |
1996年 | 27篇 |
1995年 | 32篇 |
1994年 | 18篇 |
1993年 | 19篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 10篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 9篇 |
1984年 | 13篇 |
1983年 | 3篇 |
1982年 | 12篇 |
1981年 | 7篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有1856条查询结果,搜索用时 15 毫秒
161.
Wai Ki Ching 《Communications Letters, IEEE》1999,3(2):34-36
In this letter, we consider the convergence of an asynchronous greedy algorithm with relaxation for Nash equilibrium in a noncooperative multiclass queueing environment. The process of an asynchronous greedy algorithm is equivalent to the iteration of the Jacobi method in solving a linear system. However, it has been proved that the algorithm converges only for some particular range of queueing parameters. Here we propose the asynchronous greedy algorithm with relaxation, which is in principle equivalent to solving a linear system by the Jacobi method with relaxation. We propose also some relaxation parameters such that our algorithm converges very fast 相似文献
162.
163.
Efficiency, reliability, and cost are the important design considerations of a vertical double diffused MOSFET (VDMOS) because of its high-voltage applications in consumer electronics. To minimize the cost, the devices were normally fabricated on an epitaxial layer which was grown on a highly-doped substrate. Meanwhile, it was proposed that the efficiency of a VDMOS can be enhanced by conducting an anti-JFET implant to reduce the “ON” resistance of the transistor. This paper reports the effects of anti-JFET implant on the reliability and the blocking capability of the VDMOS. Experimental results show that the anti-JFET implant can reduce the ON resistance by suppressing the channel depletion due to the parasitic JFET and enhance the breakdown voltage by moving the high-field region to the surface channel region. However, it deteriorates the device reliability greatly because the oxide quality was deteriorated and the hot holes generated in the surface high-field region could be easily injected into the gate oxide and hence caused larger subthreshold conduction and drain breakdown at lower voltage. 相似文献
164.
Research suggests that human limitations are rarely considered in the design of knowledge-based authentication systems. In an attempt to foster entry to a system, individuals tend to choose passwords which are easy to recall. However, inappropriate selection can compromise data security. A novel approach has been developed to restore the balance between security and memorability through the use of the haptic channel. This paper introduces the Tactile Authentication System (TAS), which enables the user to authenticate entry through the ability to remember a sequence of pre-selected tactile sensations. The design process undertaken to develop distinguishable tactile stimuli for use within TAS is described, and details of the recognition-based tactile authentication mechanism are also presented. Findings from an empirical study reported in this paper, have revealed that 16 participants were able to authenticate access to TAS over the course of a one-month period, with low levels of error. The approach was found to offer benefits over conventional visual-based authentication methods. Tactile stimuli are presented underneath the fingertips, and are therefore occluded from others. As the sense of touch is personal to each user, tactile stimuli are difficult to describe in concrete terms, and cannot easily be written down or disclosed, thereby reducing the chance of unauthorized third party access. 相似文献
165.
Kok Kee Yang M. R. Mahmoudian Mehdi Ebadi Hun Lee Koay Wan Jeffrey Basirun 《Metallurgical and Materials Transactions B》2011,42(6):1274-1279
Voltammetry and chronoamperometry for the electrodeposition of tin from Tin(II) methane sulfonate mixed with ionic liquid
and methane sulfonate acid at room temperature was studied. Cyclic voltammetry shows redox waves of Tin(II), which proves
that the electrodeposition of tin from Tin(II) methane sulfonate is a diffusion-controlled process. The diffusion coefficient
of Tin(II) ions in the solvent mixture showed good agreement from both voltammetry and chronoamperometry results. The diffusion
coefficient of Tin(II) in the mixture was much smaller than in aqueous solution, and it depends on the anion of the ionic
liquid. 相似文献
166.
In this article, the effect of resin finish on the degree of set is discussed. Furthermore, the relationship of the degree of set and dimensional stability is analyzed. After relaxation treatments, the yarns in a fabric would be set at a certain level. As the fabric is subjected to prolonged relaxation treatments, the yarn will become more set until the shape of the unraveled yarn is similar to the shape of the loop in the fabric. The yarn that is removed from a knitted fabric has a curvature value close to zero, and the curvature is exactly as the corresponding position at the knitted loop. From previous research, it is known that the degree of set affects the dimensional properties in a plain knitted fabric. In this article, the degree of set increases with resin level. It explains why the resin finish can stabilize the dimensional properties indirectly. 相似文献
167.
Jee Weng Tan Kwai Lin Thong Nirmala Devi Arumugam Wai Lian Cheah Yih Wei Lai Kek Heng Chua Raha Abdul Rahim Sabaratnam Vikineswary 《International Journal of Hydrogen Energy》2009,34(17):7538-7541
Molybdenum (Mo) nitrogenases consist of two components: dinitrogenase reductase (encoded by nifH) and the dinitrogenase or MoFe protein (encoded by nifDK). Nitrogenase enzyme of photosynthetic bacteria is responsible for hydrogen production. Therefore, primers were designed for the nitrogenase gene only. In this study, two primers (ND and NH) were designed after comparative genomic analysis of nifH and nifD gene sequences from public databases. The designed primers were used for the amplification of nifH and nifD genes to detect nitrogenase genes in photosynthetic bacteria. Initial detection was done using a monoplex Polymerase Chain Reactions (PCRs) followed by optimization of the PCR protocols. Subsequently, a duplex PCR was designed for amplification and detection of nifH and nifD genes in indigenous photosynthetic bacteria. Evaluation of the duplex PCR on six samples isolated from Palm Oil Mill Effluent (POME) showed that only four isolates contained both the nifH and nifD genes, indicating that these isolates were potential hydrogen-producing bacteria. PCR detection provides a rapid and efficient pre-identification of potential photosynthetic bacterial hydrogen producers. 相似文献
168.
High-ranking officers require advanced military education in war tactics for future combat. However, line officers rarely have time to take such courses on campus. The conventional solution to this problem used to take the inefficient correspondence courses. Whereas Internet technologies progress, online course is the current trend for military training. However, the question is what distance learning methodology best suits such a proprietary learning purpose.This study presents a sequential process of developing distance learning courses in advanced military education. Further, the Petri-Net analytical approach is adopted to discover the essential interaction requirements of advanced military education delivered via Internet. This study developed a systematic method for designing e-learning systems according to specific requirements of target courses. The proposed approach starts by comparing on-campus programs with the existing e-learning systems to identify the steps required to transform the program into an e-learning system. After first outlining the pedagogy of the on-campus program, its proposed teaching flow through the Internet is then sketched. Finally, the Petri-Net model was used for in-depth analysis of the stages affecting the learning curve of the line office taking e-learning courses. The example of a “Joint Operations” AME course elaborated the presented approach. An e-learning system prototype was also designed accordingly. Lastly, an experiment was conducted to verify the efficiency of the presented approach. 相似文献
169.
This paper investigates the problem of tone interference within the very small aperture terminal (VSAT) binary phase-shift keying (BPSK) signal spectrum. The degree of performance degradation of a VSAT link in the presence of a tone interference is discussed. A simple theoretical analysis is derived, and its validity is verified by experimental measurements performed using a standard commercial VSAT modem measurement setup 相似文献
170.
Existing IP routing algorithms have been developed mainly for non‐VLAN networks. For these routing algorithms to work, an end station must be attached to its associated network. The introduction of VLAN has, however, allowed the physical location of the end station to be changed from time to time. Therefore, some extra mechanism is required to support routing in VLAN environment. Existing approaches have some drawbacks in terms of inefficiency in traffic forwarding and switch software complexity. In this paper, a simple and efficient method for routing over IP subnet VLAN in Ethernet is proposed. This method has been implemented in hardware and found to work correctly. Various measurements and analyses have been performed to verify the efficiency of this protocol. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献