全文获取类型
收费全文 | 1308篇 |
免费 | 72篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 23篇 |
综合类 | 6篇 |
化学工业 | 288篇 |
金属工艺 | 36篇 |
机械仪表 | 30篇 |
建筑科学 | 72篇 |
矿业工程 | 3篇 |
能源动力 | 96篇 |
轻工业 | 92篇 |
水利工程 | 13篇 |
石油天然气 | 9篇 |
无线电 | 147篇 |
一般工业技术 | 200篇 |
冶金工业 | 129篇 |
原子能技术 | 3篇 |
自动化技术 | 245篇 |
出版年
2024年 | 3篇 |
2023年 | 30篇 |
2022年 | 53篇 |
2021年 | 70篇 |
2020年 | 51篇 |
2019年 | 52篇 |
2018年 | 73篇 |
2017年 | 48篇 |
2016年 | 71篇 |
2015年 | 40篇 |
2014年 | 58篇 |
2013年 | 103篇 |
2012年 | 82篇 |
2011年 | 114篇 |
2010年 | 74篇 |
2009年 | 74篇 |
2008年 | 61篇 |
2007年 | 55篇 |
2006年 | 51篇 |
2005年 | 38篇 |
2004年 | 35篇 |
2003年 | 31篇 |
2002年 | 16篇 |
2001年 | 21篇 |
2000年 | 3篇 |
1999年 | 12篇 |
1998年 | 13篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 8篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有1392条查询结果,搜索用时 10 毫秒
1.
El-Mansy M. A. M. Suvitha A. Osman W. Khaled Khaled F. 《Journal of Computational Electronics》2021,20(6):2387-2402
Journal of Computational Electronics - Density functional theory as well as molecular mechanics force field (MMFF94) techniques are used to study intermolecular/intramolecular interactions, band... 相似文献
2.
In real manufacturing environments, the control of some elements in systems based on robotic cells, such as transport robots has some difficulties when planning operations dynamically. The Job Shop scheduling Problem with Transportation times and Many Robots (JSPT-MR) is a generalization of the classical Job Shop scheduling Problem (JSP) where a set of jobs additionally have to be transported between machines by several transport robots. Hence, the JSPT-MR is more computationally difficult than the JSP presenting two NP-hard problems simultaneously: the job shop scheduling problem and the robot routing problem. This paper proposes a hybrid metaheuristic approach based on clustered holonic multiagent model for the JSPT-MR. Firstly, a scheduler agent applies a Neighborhood-based Genetic Algorithm (NGA) for a global exploration of the search space. Secondly, a set of cluster agents uses a tabu search technique to guide the research in promising regions. Computational results are presented using two sets of benchmark literature instances. New upper bounds are found, showing the effectiveness of the presented approach. 相似文献
3.
We prove the existence of optimal relaxed controls as well as strict optimal controls for systems governed by non linear forward-backward stochastic differential equations (FBSDEs). Our approach is based on weak convergence techniques for the associated FBSDEs in the Jakubowski S-topology and a suitable Skorokhod representation theorem. 相似文献
4.
Ga2O3, Se metal, SnO, Sb2O3, HgO and PbCO3 are formed upon the reaction of acetamide aqueous solutions with Ga(NO3)3, SeO2, SnCl2, SbCl3, HgCl2 and Pb(NO3)2, respectively, at 90°C. Different amorphous or crystalline phases can be obtained depending upon the experimental conditions (molar ratios, metal salts and temperature). The chemical mechanisms for the formations of this metal, oxides or carbonate are discussed and the X-ray diffraction, scanning electron microscopy (SEM) and atomic force microscope (AFM) are described. The type of metal ions plays an important role in the decomposition of acetamide, leading to the formation of solid stable (metal, oxides or carbonate), soluble and gases species. These new precursors are more stable preventing the rapid precipitation of metal, oxides or carbonate. Furthermore, this route allows the formation of pure compounds in solutions. 相似文献
5.
Khaled M. El-Sawy Amr M.I. Sweedan 《Tunnelling and Underground Space Technology incorporating Trenchless Technology Research》2010,25(6):689-701
The paper reports the results of an extensive numerical simulation to estimate the elastic buckling pressure and the corresponding thrust and bending moment induced in loosely fitted thin liners. The study is conducted numerically using a two-dimensional (2D) non-linear finite element model that accounts for the effects of large deformations on the stability of loosely fitted liners. The finite element results together with a non-linear multi-variant regression analysis are used to develop simplified non-dimensional formulae that provide the critical pressure, thrust and bending moments, at buckling, based on the liner’s geometry and material properties.In addition, several other analytical and numerical solutions for the same problem are revisited and critically reviewed. For comparison purposes, two of such methods are extended to allow for the calculation of the thrust and bending moment developed at the most heavily stressed point in the loosely fitted liners at the onset of buckling. In general, the comparison reveals the appropriateness of the proposed regression models in predicting the critical pressure and the associated thrust and bending moment induced in imperfect loosely fitted liners. Developed formulae provide designers with a simple and reliable means for ensuring stability and safety of such special type of structures. 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.
David A. J. Moran Helen McLelland Khaled Elgaid Griogair Whyte Colin R. Stanley Iain Thayne 《Electron Devices, IEEE Transactions on》2006,53(12):2920-2925
Continued research into the development of III-V high-electron mobility transistors (HEMTs), specifically the minimization of the device gate length, has yielded the fastest performance reported for any three terminal devices to date. In addition, more recent research has begun to focus on reducing the parasitic device elements such as access resistance and gate fringing capacitance, which become crucial for short gate length device performance maximization. Adopting a self-aligned T-gate architecture is one method used to reduce parasitic device access resistance, but at the cost of increasing parasitic gate fringing capacitances. As the device gate length is then reduced, the benefits of the self-aligned gate process come into question, as at these ultrashort-gate dimensions, the magnitude of the static fringing capacitances will have a greater impact on performance. To better understand the influence of these issues on the dc and RF performance of short gate length InP pHEMTs, the authors present a comparison between In0.7Ga0.3As channel 50-nm self-aligned and "standard" T-gate devices. Figures of merit for these devices include transconductance greater than 1.9 S/mm, drive current in the range 1.4 A/mm, and fT up to 490 GHz. Simulation of the parasitic capacitances associated with the self-aligned gate structure then leads a discussion concerning the realistic benefits of incorporating the self-aligned gate process into a sub-50-nm HEMT system 相似文献
8.
Moez Kthiri Hassen Loukil Ahmed Ben Atitallah Patrice Kadionik Dominique Dallet Nouri Masmoudi 《Journal of Signal Processing Systems》2012,68(2):273-285
Motion estimation is a highly computational demanding operation during video compression process and significantly affects
the output quality of an encoded sequence. Special hardware architectures are required to achieve real-time compression performance.
Many fast search block matching motion estimation (BMME) algorithms have been developed in order to minimize search positions
and speed up computation but they do not take into account how they can be effectively implemented by hardware. In this paper,
we propose three new hardware architectures of fast search block matching motion estimation algorithm using Line Diamond Parallel
Search (LDPS) for H.264/AVC video coding system. These architectures use pipeline and parallel processing techniques and present
minimum latency, maximum throughput and full utilization of hardware resources. The VHDL code has been tested and can work
at high frequency in a Xilinx Virtex-5 FPGA circuit for the three proposed architectures. 相似文献
9.
Assaleh K 《IEEE transactions on bio-medical engineering》2007,54(1):59-68
In this paper, we investigate the use of adaptive neuro-fuzzy inference systems (ANFIS) for fetal electrocardiogram (FECG) extraction from two ECG signals recorded at the thoracic and abdominal areas of the mother's skin. The thoracic ECG is assumed to be almost completely maternal (MECG) while the abdominal ECG is considered to be composite as it contains both the mother's and the fetus' ECG signals. The maternal component in the abdominal ECG signal is a nonlinearly transformed version of the MECG. We use an ANFIS network to identify this nonlinear relationship, and to align the MECG signal with the maternal component in the abdominal ECG signal. Thus, we extract the FECG component by subtracting the aligned version of the MECG signal from the abdominal ECG signal. We validate our technique on both real and synthetic ECG signals. Our results demonstrate the effectiveness of the proposed technique in extracting the FECG component from abdominal signals of very low maternal to fetal signal-to-noise ratios. The results also show that the technique is capable of extracting the FECG even when it is totally embedded within the maternal QRS complex. 相似文献
10.
Masugi Inoue Khaled Mahmud Homare Murakami Mikio Hasegawa Hiroyuki Morikawa 《Wireless Personal Communications》2005,35(1-2):53-70
A context-based adaptive communication system is introduced for use in heterogeneous networks. Context includes the user's
presence, location, available network interfaces, network availability, network priority, communication status, terminal features,
and installed applications. An experimental system was developed to clarify the feasibility of using context information to
flexibly control networks and applications. The system operates on a seamless networking platform we developed for heterogeneous
networks. By using contexts, the system can inform the caller and callee of applications they can access, which are available
through the network before communication occurs. Changes in contexts can switch an on-going application to another during
actual communication. These functions provide unprecedented styles of communication. A business scenario for a seamless networking
provider is also presented.
Dr. Morikawa has also been in charge of NICT's Mobile Networking Group.
Masugi Inoue received his B.E. from Kyoto University in 1992 and his M.E. and D.E. from the University of Tokyo in 1994 and 1997, all
in the field of Electrical Engineering. He is currently a senior researcher at the Yokosuka Radio Communications Research
Center under the National Institute of Information and Communications Technology (NICT), Japan, and has been engaged in R&D
on ultrahigh-speed WLANs and mobile networking. He joined the Communications Research Laboratory (CRL) of the Ministry of
Posts and Telecommunications, Japan, in 1997, which was reorganized as NICT in April 2004. He was a visiting researcher at
Polytechnic University in Brooklyn, New York in 2000.
Khaled Mahmud received his B.Sc. (Eng.) in Electrical and Electronics Engineering from the Bangladesh University of Engineering and Technology
in Dhaka in 1991. He received his M.E. and Ph.D. in the same field from Shizuoka University in Japan, in 1997 and 2000, respectively.
He was a research fellow at NICT, Japan, from 2000 to 2004. He is currently an Assistant Professor in the Department of Computer
Science and Engineering at North South University, Bangladesh. His research interests include modulation-demodulation techniques,
software radio, mobile communication systems, wireless Internet, and IP mobility technologies.
Homare Murakami received his B.E. and M.E. in Electronic Engineering from Hokkaido University in 1997 and 1999. In 2004, he received the
Young Investigators Award from IEICE. He is currently a researcher at NICT's Mobile Networking Group. He is also an industrial
PhD student in Aalborg University since 2003. His interest areas are naming scheme, wireless TCP and new transport protocol,
IP mobility, fast handover method, and location management.
Mikio Hasegawa received his B. Eng, M. Eng., and Dr. Eng. in 1995, 1997, and 2000 from Science University of Tokyo. From 1997 to 2000, he
was a Research Fellow of the Japan Society for the Promotion of Science (JSPS). He is currently a senior researcher in Mobile
Networking Group, National Institute of Information and Communications Technology, and a technical advisor in ChaosWare Inc.
His research interests include applications of chaotic dynamical theory, combinatorial optimization, mobile networks, and
ubiquitous computing.
Hiroyuki Morikawa received his B.E., M.E., and D.E. in Electrical Engineering from the University of Tokyo in 1987, 1989, and 1992. He is currently
an Associate Professor in the Department of Frontier Informatics at the University of Tokyo and is in charge of NICT's Mobile
Networking Group. His research interests are in the areas of computer networks, mobile computing/networks, ubiquitous computing,
and network services. He serves as Editor of Transactions of the IEICE and has been on the technical program committees of
IEEE/ACM conferences and workshops. He sits on numerous telecommunications advisory committees and frequently serves as a
consultant to the government. 相似文献