全文获取类型
收费全文 | 5767篇 |
免费 | 341篇 |
国内免费 | 18篇 |
专业分类
电工技术 | 81篇 |
综合类 | 3篇 |
化学工业 | 1208篇 |
金属工艺 | 182篇 |
机械仪表 | 262篇 |
建筑科学 | 171篇 |
矿业工程 | 2篇 |
能源动力 | 297篇 |
轻工业 | 674篇 |
水利工程 | 34篇 |
石油天然气 | 17篇 |
无线电 | 818篇 |
一般工业技术 | 1167篇 |
冶金工业 | 438篇 |
原子能技术 | 41篇 |
自动化技术 | 731篇 |
出版年
2024年 | 17篇 |
2023年 | 48篇 |
2022年 | 110篇 |
2021年 | 213篇 |
2020年 | 173篇 |
2019年 | 159篇 |
2018年 | 218篇 |
2017年 | 204篇 |
2016年 | 243篇 |
2015年 | 169篇 |
2014年 | 243篇 |
2013年 | 424篇 |
2012年 | 340篇 |
2011年 | 424篇 |
2010年 | 303篇 |
2009年 | 343篇 |
2008年 | 320篇 |
2007年 | 264篇 |
2006年 | 208篇 |
2005年 | 156篇 |
2004年 | 147篇 |
2003年 | 130篇 |
2002年 | 97篇 |
2001年 | 105篇 |
2000年 | 85篇 |
1999年 | 83篇 |
1998年 | 174篇 |
1997年 | 125篇 |
1996年 | 95篇 |
1995年 | 67篇 |
1994年 | 64篇 |
1993年 | 53篇 |
1992年 | 38篇 |
1991年 | 46篇 |
1990年 | 26篇 |
1989年 | 30篇 |
1988年 | 27篇 |
1987年 | 15篇 |
1986年 | 17篇 |
1985年 | 9篇 |
1984年 | 16篇 |
1983年 | 13篇 |
1982年 | 13篇 |
1981年 | 10篇 |
1980年 | 11篇 |
1979年 | 5篇 |
1977年 | 8篇 |
1976年 | 14篇 |
1974年 | 4篇 |
1972年 | 3篇 |
排序方式: 共有6126条查询结果,搜索用时 15 毫秒
31.
Anjan Biswas Sonmezoglu Abdullah Ekici Mehmet Alzahrani Abdullah Khamis Belic Milivoj R. 《Journal of Communications Technology and Electronics》2020,65(12):1384-1398
Journal of Communications Technology and Electronics - This paper implements mathematically rigorous extended trial function algorithm to address cubic–quartic optical solitons in... 相似文献
32.
You-Chang Ko Roy S. Choong-Ho Cho Hyong-Woo Lee Garg H.K. 《Communications Letters, IEEE》2009,13(9):640-642
This letter introduces a new tree-based anti-collision scheme using multiple feedbacks for uplink tag random access in a single-cell scenario. We examine MAC efficiency improvements that result from the proposed scheme in terms of uplink (UL) throughput for emerging radio frequency identification (RFID) networks, and compare it with the conventional tree based RFID MAC in ISO 18000-6 Type B standard. 相似文献
33.
Dohyung Kim Hyeonsu Bang Hyoung Won Baac Jongmin Lee Phuoc Loc Truong Bum Ho Jeong Tamilselvan Appadurai Kyu Kwan Park Donghyeok Heo Vu Binh Nam Hocheon Yoo Kyeounghak Kim Daeho Lee Jong Hwan Ko Hui Joon Park 《Advanced functional materials》2023,33(14):2213064
Reversible metal-filamentary mechanism has been widely investigated to design an analog resistive switching memory (RSM) for neuromorphic hardware-implementation. However, uncontrollable filament-formation, inducing its reliability issues, has been a fundamental challenge. Here, an analog RSM with 3D ion transport channels that can provide unprecedentedly high reliability and robustness is demonstrated. This architecture is realized by a laser-assisted photo-thermochemical process, compatible with the back-end-of-line process and even applicable to a flexible format. These superior characteristics also lead to the proposal of a practical adaptive learning rule for hardware neural networks that can significantly simplify the voltage pulse application methodology even with high computing accuracy. A neural network, which can perform the biological tissue classification task using the ultrasound signals, is designed, and the simulation results confirm that this practical adaptive learning rule is efficient enough to classify these weak and complicated signals with high accuracy (97%). Furthermore, the proposed RSM can work as a diffusive-memristor at the opposite voltage polarity, exhibiting extremely stable threshold switching characteristics. In this mode, several crucial operations in biological nervous systems, such as Ca2+ dynamics and nonlinear integrate-and-fire functions of neurons, are successfully emulated. This reconfigurability is also exceedingly beneficial for decreasing the complexity of systems—requiring both drift- and diffusive-memristors. 相似文献
34.
Anwar Syed Muhammad Irmakci Ismail Torigian Drew A. Jambawalikar Sachin Papadakis Georgios Z. Akgun Can Ellermann Jutta Akcakaya Mehmet Bagci Ulas 《Journal of Signal Processing Systems》2022,94(5):497-510
Journal of Signal Processing Systems - Segmentation of thigh tissues (muscle, fat, inter-muscular adipose tissue (IMAT), bone, and bone marrow) from magnetic resonance imaging (MRI) scans is useful... 相似文献
35.
Cognitive radio has attracted considerable attention as an enabling technology for addressing the problem of radio frequency shortages. In cognitive radio networks (CRNs), secondary users (SUs) are allowed to opportunistically utilize the licensed spectrum bands of primary users (PUs) when these bands are temporarily unused. Thus, SUs should monitor the licensed spectrum bands to detect any PU signal. According to the sensing outcomes, SUs should vacate the spectrum bands or may use them. Generally, the spectrum sensing accuracy depends on the sensing time which influences the overall throughput of SUs. That is, there is a fundamental tradeoff between the spectrum sensing time and the achievable throughput of SUs. To determine the optimal sensing time and improve the throughput of SUs, considerable efforts have been expended under the saturated traffic and ideal channel assumptions. However, these assumptions are hardly valid in practical CRNs. In this paper, we provide the framework of an 802.11-based medium access control for CRNs, and we analyze this framework to find the optimal spectrum sensing time under the saturated and unsaturated traffic condition. Through simulation, the proposed analytic model is verified and the fundamental problem of the sensing-throughput tradeoff for CRNs is investigated. 相似文献
36.
Yongseok Lee Changjun Ko Hodong Lee Kyeongwoo Jeon Seolin Shin Chonghun Han 《石油科学(英文版)》2017,14(3):529-538
This study proposes a method of interactive plant simulation modeling which delivers the online simulated results to the field operators and induces them to take proper actions in the case of pre-identified accident scenarios in a chemical plant. The developed model integrates the real-time process dynamic simulation with 3DCFD accident simulation in a designed interface using object linking and embedding technology so that it can convey to trainees the online information of the accident which is not available in existing operator training systems. The model encompasses the whole process of data transfer till the end of the training at which a trainee operates an emergency shutdown system in a programmed model. In this work, an overall scenario is simulated which is from an abnormal increase in the main valve discharge (second) pressure due to valve malfunction to accidental gas release through the crack of a pressure recorder, and the magnitude of the accident with respect to the lead time of each trainee’s emergency response is analyzed. The model can improve the effectiveness of the operator training system through interactively linking the trainee actions with the simulation model resulting in different accident scenarios with respect to each trainee’s competence when facing an accident. 相似文献
37.
Xiaoli Xu Richard T. Kuehn Mehmet C. Öztürk Jimmie J. Wortman Robert J. Nemanich Gari S. Harris Dennis M. Maher 《Journal of Electronic Materials》1993,22(3):335-339
Various silicon surface cleaning processes for rapid thermal in-situ polysilicon/ oxide/silicon stacked gate structures have
been evaluated. Metal-oxide-semiconductor capacitors were fabricated to assess the effects of cleaning on the quality of gate
oxide structures produced by both rapid thermal oxidation (RTO) and rapid thermal chemical vapor deposition (RTCVD). Excellent
electrical properties have been achieved for both RTO and RTCVD gate oxides formed on silicon wafers using either an ultraviole/zone
(UV/O3) treatment or a modified RCA clean. On the contrary, poor electrical properties have been observed for RTO and RTCVD gate
oxides formed on silicon wafers using a high temperature bake in Ar, H2, or high vacuum ambient. It has also been found that the electrical properties of the RTCVD gate oxides exhibit less dependence
upon cleaning conditions than those of RTO gate oxides. This work demonstrates that initial surface condition prior to gate
oxide formation plays an important role in determining the quality of RTO and RTCVD gate oxides. 相似文献
38.
加热到1173K的Cu-25at;%Al合金块状试样经723K60S等温淬火后其组织由片状的“羽毛状贝氏体(9R结构)和β_1'马氏体(18R结构)组成。当试样被离子束轰去进一步薄化后,在足够薄的区域内生成了许多2H结构的薄片马氏体。初步分析认为该薄片马氏体形成的原因是由于贝氏体生成时在试样内留下了高的应力场,当试样薄化到一临界厚度以下时,试样区的三维约束条件松弛使试样内的应力场触发了薄片马氏体的生成。这些薄片马氏体是通过位于贝氏体界面上位错的重新启动而长大的。 相似文献
39.
Bit error rate (BER) performance of differential 16STAR-QAM in frequency-selective Rician fading channels with diversity reception is theoretically analysed for three different types of delay profiles: double spike, one-sided exponential and Gaussian profiles. The effect of time delay between line-of-sight (LOS) and multipath components is also included in the analysis, and is shown to degrade the system performance significantly 相似文献
40.
An algorithm for spatially filtering out, enhancing, and tracking individual directional sources in an adaptive array is proposed and investigated. In this algorithm, the sources are separated by using an adaptive beamformer whose outputs are processed by using the LMS algorithm to track distinct sources individually. From the LMS weights used, the source locations can be estimated. Whenever significant changes in these are detected, the beamformer is updated so that its outputs will be due to different sources in the steady state. With this algorithm, the problems of look-direction errors in look-direction constrained arrays and of large signal power in power inversion arrays are eliminated, and the enhancement of multiple moving sources becomes a natural process. Furthermore, because the sources are individually tracked and the beamformer is only updated occasionally, the algorithm possesses fast tracking behavior, and its implementation complexity is comparable to that of beamformer-based adaptive arrays using the LMS algorithm 相似文献