全文获取类型
收费全文 | 4376篇 |
免费 | 509篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 47篇 |
综合类 | 1篇 |
化学工业 | 1371篇 |
金属工艺 | 176篇 |
机械仪表 | 298篇 |
建筑科学 | 58篇 |
矿业工程 | 1篇 |
能源动力 | 200篇 |
轻工业 | 293篇 |
水利工程 | 3篇 |
石油天然气 | 4篇 |
无线电 | 805篇 |
一般工业技术 | 1087篇 |
冶金工业 | 116篇 |
原子能技术 | 64篇 |
自动化技术 | 366篇 |
出版年
2024年 | 4篇 |
2023年 | 51篇 |
2022年 | 70篇 |
2021年 | 145篇 |
2020年 | 119篇 |
2019年 | 137篇 |
2018年 | 165篇 |
2017年 | 178篇 |
2016年 | 226篇 |
2015年 | 187篇 |
2014年 | 241篇 |
2013年 | 279篇 |
2012年 | 354篇 |
2011年 | 410篇 |
2010年 | 248篇 |
2009年 | 333篇 |
2008年 | 267篇 |
2007年 | 200篇 |
2006年 | 181篇 |
2005年 | 133篇 |
2004年 | 127篇 |
2003年 | 154篇 |
2002年 | 112篇 |
2001年 | 82篇 |
2000年 | 77篇 |
1999年 | 70篇 |
1998年 | 71篇 |
1997年 | 47篇 |
1996年 | 46篇 |
1995年 | 39篇 |
1994年 | 15篇 |
1993年 | 23篇 |
1992年 | 14篇 |
1991年 | 16篇 |
1990年 | 13篇 |
1989年 | 14篇 |
1988年 | 8篇 |
1987年 | 11篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1980年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有4890条查询结果,搜索用时 15 毫秒
81.
Sanghwan Choi Eungchul Kim Hyunho Seok Taesung Kim 《Advanced Engineering Materials》2023,25(16):2370055
Polycrystalline silicon (poly-Si) is widely used as a gate layer in integrated circuits, transistors, and channels through nanofabrication. Nanoremoval and roughness control are required for nanomanufacturing of various electronic devices. Herein, a nanoscale removal method is developed to overcome the limitations of microcracks, complex procedures, and time-consuming conventional fabrication and lithography methods. The method is implemented with a mechanically induced poly-Si phase transition using atomic force microscope (AFM). Mechanical force induces the covalent bonds between silicon and fluorine atoms which cause the phase transition of poly-Si. Then, the bond structure of the Si molecules is weakened and selectively removed by nano-Newton-scale force using AFM. A selective nanoscale removal with roughness control is implemented in 0.5 mM TBAF solution after mechanical force (43.58–58.21 nN) is applied. By the magnitude of nano-Newton force, the removal depth of poly-Si is controlled from 2.66 to 21.52 nm. Finally, the nanoscale fabrication on poly-Si wafer is achieved. The proposed nanoremoval mechanism is a simple fabrication method that provides selective, nanoscale, and highly efficient removal with roughness control. 相似文献
82.
Kien Tiek Wong Boris Brigljević Jeong Hyeon Lee So Yeon Yoon Seok Byum Jang Choe Earn Choong Inwook Nah Hyeongjun Kim Hyun-Seog Roh Sang Kyu Kwak Hankwon Lim Min Jang 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(1):2204336
This study focuses on the applicability of single-atom Mo-doped graphitic carbon nitride (GCN) nanosheets which are specifically engineered with high surface area (exfoliated GCN), NH2 rich edges, and maximum utilization of isolated atomic Mo for propylene carbonate (PC) production through CO2 cycloaddition of propylene oxide (PO). Various operational parameters are optimized, for example, temperature (130 °C), pressure (20 bar), catalyst (Mo2GCN), and catalyst mass (0.1 g). Under optimal conditions, 2% Mo-doped GCN (Mo2GCN) has the highest catalytic performance, especially the turnover frequency (TOF) obtained, 36.4 h−1 is higher than most reported studies. DFT simulations prove the catalytic performance of Mo2GCN significantly decreases the activation energy barrier for PO ring-opening from 50–60 to 4.903 kcal mol−1. Coexistence of Lewis acid/base group improves the CO2 cycloaddition performance by the formation of coordination bond between electron-deficient Mo atom with O atom of PO, while NH2 surface group disrupts the stability of CO2 bond by donating electrons into its low-level empty orbital. Steady-state process simulation of the industrial-scale consumes 4.4 ton h−1 of CO2 with PC production of 10.2 ton h−1. Techno-economic assessment profit from Mo2GCN is estimated to be 60.39 million USD year−1 at a catalyst loss rate of 0.01 wt% h−1. 相似文献
83.
Bong Seok Park Jin Bae Park Yoon Ho Choi 《International Journal of Control, Automation and Systems》2011,9(3):534-541
In this paper, an adaptive observer-based trajectory tracking problem is solved for nonholonomic mobile robots with uncertainties.
An adaptive observer is first developed to estimate the unmeasured velocities of a mobile robot with model uncertainties.
Using the designed observer and the backstepping technique, a trajectory tracking controller is designed to generate the torque
as an input. Using Lyapunov stability analysis, we prove that the closed-loop system is asymptotically stable with respect
to the estimation errors and tracking errors. Finally, the simulation results are presented to validate the performance and
robustness of the proposed control system against uncertainties. 相似文献
84.
In recent years, Radio Frequency Identification (RFID) industries have taken a great interest in utilizing the benefits of RFID for supply chain management, inventory control and various other applications. This paper proposed an adaptive load balancing technique for RFID middleware systems to meet the demands of scalability and heterogeneity. First, we explored five basic load balancing policies, namely, information policy, job selection policy, transfer policy, initiation policy and location policy. Eighteen load balancing schemes were then proposed for RFID middleware systems that were combinations of various types of the five basic load balancing policies. Our empirical study suggested that these load balancing strategies performed differently under different workload statuses. Finally, an adaptive load balancing strategy was proposed. The load balancing schemes and the proposed adaptive load balancing strategy have been implemented in the RFID Middleware Load Management System (RM‐LMS). Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
85.
Jung Hyeon Bae Gun Hee Kim Woong Hee Jeong Hyun Jae Kim 《Journal of the Society for Information Display》2011,19(5):404-409
Abstract— Non‐volatile memory effects of an all‐solution‐processed oxide thin‐film transistor (TFT) with ZnO nanoparticles (NPs) as the charge‐trapping layer are reported. The device was fabricated by using a soluble MgInZnO active channel on a ZrHfOx gate dielectric. ZnO NPs were used as the charge‐trapping site at the gate‐insulator—channel interface, and Al was used for source and drain electrodes. Transfer characteristics of the device showed a large clockwise hysteresis, which can be used to demonstrate its memory function due to electron trapping in the ZnO NP charge‐trapping layer. This memory effect has the potential to be utilized as a memory application on displays and disposable electronics. 相似文献
86.
Consumer perceptions on web advertisements and motivation factors to purchase in the online shopping
The principal objective of this study was to investigate the mediating and moderating effects of product involvement and trust toward websites in relation to the effects of the attributes of web advertisements on customers’ purchase intentions. We collected data consisting of a total of 264 responses from individuals with previous experience with purchasing products from online shopping mall sites, and utilized the PLS (partial least squares) method to analyze the collected data. 相似文献
87.
Sung Wook Kim Hyoung Sun Yoo Byoung‐Hwa Kwon Dong Seok Kang Minwon Suh Duk Young Jeon 《Journal of the Society for Information Display》2010,18(12):1104-1110
Abstract— In this study, organic wavelength‐converting films (WCFs) applied to InGaN blue LED‐based hybrid planar WLED has been fabricated. The organic dye layer in the WCF was formed between the upper and bottom polymer sheets by using a simple roll‐laminating technique. Subsequently, the hybrid planar WLEDs have been fabricated based upon these films. The luminous efficiency of green WCF‐based hybrid planar WLEDs with a single blue LED chip was 34.6 lm/W and that of red‐WCF‐assisted green WCF‐based hybrid planar WLEDs was 27.3 lm/W under 20 mA. The use of WCF to fabricate hybrid planar WLEDs showed better stability than that of directly coating organic color‐convergence materials (CCMs) on the LED chips. It only decreased to about 10% of the initial wavelength‐converting intensity after 1 hour of continual operation at 20 mA. 相似文献
88.
Position control of a mobile inverted pendulum system using radial basis function network 总被引:2,自引:0,他引:2
Jin Seok Noh Geun Hyung Lee Seul Jung 《International Journal of Control, Automation and Systems》2010,8(1):157-162
This article presents the implementation of position control of a mobile inverted pendulum (MIP) system by using the radial
basis function (RBF) network. The MIP has two wheels to move on the plane and to balance the pendulum. The MIP is a nonlinear
system whose dynamics is nonholonomic. The goal of this study was to control the MIP to maintain the balance of the pendulum
while tracking a desired position of the cart. The reference compensation technique scheme is used as a neural network control
method for the MIP. The back-propagation learning algorithm of the RBF network is derived for online learning and control.
The control algorithm has been embedded on a DSP 2812 board to achieve real-time control. Experimental results are conducted
and show successful control performances of both balancing and tracking the desired position of the MIP. 相似文献
89.
This paper presents an evolutionary algorithm, called the multi-objective symbiotic evolutionary algorithm (MOSEA), to solve a multi-objective FMS process planning (MFPP) problem with various flexibilities. The MFPP problem simultaneously considers four types of flexibilities related to machine, tool, sequence, and process and takes into account three objectives: balancing the machine workload, minimizing part movements, and minimizing tool changes. The MOSEA is modeled as a two-leveled structure to find a set of well-distributed solutions close to the true Pareto optimal solutions. To promote the search capability of such solutions, two main processes imitating symbiotic evolution and endosymbiotic evolution are introduced, together with an elitist strategy and a fitness sharing scheme. Evolutionary components suitable for the MFPP problem are provided. With a variety of test-bed problems, the performance of the proposed MOSEA is compared with those of existing multi-objective evolutionary algorithms. The experimental results show that the MOSEA is promising in solution convergence and diversity. 相似文献
90.
The notions of $(\overline{\in}, \overline{\in} \vee \overline{\hbox{q}})The notions of ([`( ? )],[`( ? )] ú[`q])(\overline{\in}, \overline{\in} \vee \overline{\hbox{q}})-fuzzy p-ideals and fuzzy p-ideals with thresholds related to soft set theory are discussed. Relations between ([`( ? )],[`( ? )] ú[`q])(\overline{\in}, \overline{\in} \vee \overline{\hbox{q}})-fuzzy ideals and ([`( ? )],[`( ? )] ú[`q])(\overline{\in}, \overline{\in} \vee \overline{\hbox{q}})-fuzzy p-ideals are investigated. Characterizations of an ([`( ? )],[`( ? )] ú[`q])(\overline{\in}, \overline{\in} \vee \overline{\hbox{q}})-fuzzy p-ideal and a fuzzy p-ideal with thresholds are displayed. Implication-based fuzzy p-ideals are discussed. 相似文献